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  • Electron microscopy  (538)
  • Lepidoptera  (165)
  • Calcium  (143)
  • Springer  (844)
  • Cambridge University Press
  • 1980-1984  (403)
  • 1975-1979  (441)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 261 (1983), S. 373-374 
    ISSN: 1435-1536
    Keywords: Electron microscopy ; short-time staining ; nodular structure ; crystallization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 2
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    Springer
    Colloid & polymer science 260 (1982), S. 564-569 
    ISSN: 1435-1536
    Keywords: lin. Polyethylene ; Single crystals ; Heat of Fusion ; DSC ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recently published results for solution crystallized PE single crystals have shown, that the experimental heat of fusionΔH * is higher, if the solvent is exchanged to silicon oil (oil suspension samples) as compared with dried mats. This has been interpreted by the collapse of the original hollow pyramids during drying, inducing lateral defects within the lamellae. The present investigation does not confirm this unexpected result.ΔH * of dried mats (T c 66 to 91 °C) and of the corresponding oil suspension samples agree within the rather small limits of experimental error. The crystallinities as derived fromΔH *, density or WAXS are in excellent agreement. SEM micrographs of cold fractured dried mats show their spongy macromorphology, but TEM micrographs of stained ultra-thin sections reveal the lamellar morphology of the walls, consisting of curved lamellae and stacked hollow pyramides. If a dried mat is sintered at room temperature, a dense transparent film is obtained with a rather regular stacked morphology of large flat lamellae.ΔH * of these films agrees with that of the original mat.
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  • 3
    Electronic Resource
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    Springer
    Monatshefte für Chemie 112 (1981), S. 149-156 
    ISSN: 1434-4475
    Keywords: Calcium ; Gallium ; Oxygen ; Single Crystal ; X-Ray
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The hitherto unknown compound Ca3Ga4O9 was prepared and investigated by X-ray single crystal methods. Ca3Ga4O9 has orthorhombic symmetry:a=1435.8;b=1682.5;c=532.1 pm; space group C 2v 11 −Cmm2,Z=6. The tetrahedra network (circles of 4 and 5 GaO4-tetrahedra) and the surrounding of Ca2+ are described and discussed with respect to other oxogallates.
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  • 4
    ISSN: 1570-7458
    Keywords: host-plant relations ; host variation ; Malacosoma americanum ; Malacosoma disstria ; Lasiocampidae ; Geometridae ; Lepidoptera ; niche breadth ; specialization ; plantinsect interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Raupen von Malacosoma americanum (F.), einer oligophagen Art, die sich vor allem auf Prunus und andern baumartigen Rosaceen entwickelt, wurden verglichen mit Raupen der polyphageren Verwandten M. disstria Hb. und zwar im Hinblick auf deren Empfindlichkeit auf Unterschiede im Blatt ihrer gemeinsamen Wirtspflanze, Prunus serotina Ehrh. Das Puppengewicht und die Entwicklungszeit bis zur Verpuppung wurden gemessen bei Raupen, welche auf Blättern von freiwachsenden und von beschatteten Jungpflanzen gezüchtet worden waren. Die Blattunterschiede hatten eine ausgesprochene Wirkung, aber es gab keine Unterschiede in der Reaktion der beiden Arten. Dieser Vergleich lässt vermuten, dass die Empfindlichkeit auf intraspezifische Unterschiede der Wirtspflanzenqualität bei wirtsspezifischen und polyphagen Arten gleich ist. Indessen dürften sich laut anderen Resultaten einige Insektenarten anders verhalten.
    Notes: Abstract Larvae of Malacosoma americanum (F.)(Lepidoptera: Lasiocampidae) an oligophagous species that feeds primarily on Prunus and other rosaceous trees, were compared to larvae of the more highly polyphagous congener M. disstria Hb., with respect to their sensitivity to variation in the foliage of a common host plant, Prunus serotina Ehrh. Pupal weight and time to pupation were measured on larvae reared on foliage from open-grown and from shaded saplings. The difference in foliage had a pronounced effect, but no difference was evident between the species in their response to the variation in foliage. This comparison implies that sensitivity to intraspecific variation in host quality does not differ between host-specific and generalized species. However, results from other species suggest that some species of insects do differ in this respect.
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  • 5
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    Springer
    Entomologia experimentalis et applicata 30 (1981), S. 106-110 
    ISSN: 1570-7458
    Keywords: assimilation efficiency ; growth efficiency ; niche breadth ; specialization ; hostplant relations ; plant-insect interactions ; Malacosoma americanum ; Malacosoma disstria ; Lasiocampidae ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Raupen von Malacosoma americanum, einer oligophagen Art, die sich vor allem auf Prunus und andern baumartigen Rosaceen. entwickelt, wurden mit Raupen der polyphageren Verwandten M. disstria in Hinblick auf die Verwertung der Blätter ihres gemeinsames Wirtes Prunus serotina verglichen. Wirerhielten ähnliche Werte wie sie früher für andere Lepidopteren publiziert worden waren und zwar in Bezug auf die üblichen Messwerte, Anteil verwertete Nahrung, Wachstum in Trockengewicht pro Einheit gefressene oder verwertete Nahrung. Zudem unterschieden sich die beiden Arten in keiner Masszahl für Effizienz. Unsere Resultate sind im Einklang mit der Folgerung, das spezialisierte phytophage Insekten ihre Wirtspflanzen nicht besser ausnützen als as polyphage Arten tun.
    Notes: Abstract Larvae of Malacosoma americanum (F.) an oligophagous species that feeds primarily on Prunus and other rosaceous trees, were compared to larvae of the more highly polyphagous congener M. disstria Hb., with respect to the efficiency of utilization of the foliage of a common host plant, Prunus serotina Ehrh. We obtained values similar to those reported for other Lepidoptera for the commonly used measures of the fraction of ingested food that was assimilated, and for the growth in dry weight per unit of food ingested or assimilated. Moreover, the two species did not differ in any measure of efficiency. Our results are compatible with the conclusion that specialized phytophagous insects do not use their host plants with greater physiological efficiency than do generalized insects.
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  • 6
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    Entomologia experimentalis et applicata 34 (1983), S. 174-178 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Pyralidae ; Maruca testulalis ; Pod borer ; Development ; Nutritional suitability ; Host plant ; Crotalaria ; Vigna unguiculata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les possibilités de développement larvaire de Maruca testulalis sur les fleurs de huit espèces végétales ont été examinées en laboratoire. La comparaison a porté sur Crotalaria retusa, C. juncea, C. saltiana, C. misereniensis, C. mucronata, C. amazonas, Cajanus cajan et l'hôte principal de cette chenille, Vigna unguiculata. En tenant compte de la mortalité larvaire et des indices de croissance (G.I.), ces plantes ont été divisées en trois catégories principales: 1 celles provoquant une mortalité larvaire de 0–30% et ayant des G.I. ≥60%, constituent les plantes hôtes convenables (Vigna unguiculata seule); 2 les plantes qui provoquent une mortalité larvaire de 30≤50% et ont des G.I. de 30 à 60% de la plante hôte principale (Cajanus cajan, Crotalaria amazonas, C. saltiana, C. mucronata; 3 les plantes qui causent 50–100% de mortalité larvaire et dont les G.I. sont inférieurs à 30% de la plante hôte principale (Crotalaria retusa, C. juncea, C. misereniensis). Les résultats déjà publiés sur les choix du lieu de ponte des femelles et l'utilisation de C. juncea comme plante piège, sont discutés à la lumière de ces données nouvelles.
    Notes: Abstract Flowers of eight plant species were evaluated under laboratory conditions for their suitability as larval growth media for the cowpea pod borer, Maruca testulalis. The plants tested were Crotalaria retusa, C. juncea, C. saltiana, C. misereniensis, C. amazonas, Cajanus cajan and the principal host of the borer, Vigna unguiculata (cowpea), was included for comparison. Based on the data obtained on larval mortality and growth indices (GI) the plants were divided into 3 categories namely: I: Those causing 0–30% mortality and having GI value ≥60% form suitable host plants. This group only included V. unguiculata. — II: Those plant species causing 30≤50% larval mortality and having GI value 30%≤60% of the principal host plant (Cajanus cajan, Crotalaria amazonas, C. saltiana, C. mucronata). This group of species is marginally suitable as hosts. — III: Plants causing 50–100% larval mortality and having GI value ≤30% of principal host plant (C. retusa, C. juncea and C. misereniensis). Previously published data on the oviposition preference of the adult moth are discussed in the light of the present findings and the use of C. juncea as a possible trap crop.
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  • 7
    Electronic Resource
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    Springer
    Entomologia experimentalis et applicata 34 (1983), S. 203-205 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Sesiidae ; Synanthedon vespiformis ; Paranthrene tabaniformis ; Chamaesphecia empiformis ; Chamaesphecia tenthrediniformis ; Attractants ; Pheromones ; Clearwing moths ; Nemapogon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 8
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    Entomologia experimentalis et applicata 30 (1981), S. 280-292 
    ISSN: 1570-7458
    Keywords: Allozyme variation ; Lepidoptera ; Yponomeuta padellus ; evolutionary stages ; F-statistics ; panmixis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le degré de différenciation génétique en allozymes à des niveaux divers de divergence évolutive (populations conspécifiques, sibling species et non-sibling species) d'Yponomeuta a été déterminé. Les distances génétiques entre des sibling species ou des non-sibling species sont très larges. Il en est conclu que de telles estimations ne fournissent pas beaucoup d'informations sur le phénomène de spéciation même. Des coéfficients de reproduction consanguine (F ST) ont été calculés pour des populations d'Y. padellus provenant de six plantes-hôtes. La valeur moyenne F STest .030±.012. Les valuers de F ST des populations recueillies sur Crataegus, (plante-hôte habituelle d'Y. padellus), sont inférieures 2–3.5 fois à celles des populations de l'ensemble des autres plantes-hôtes. L'apparition de races en fonction de l'hôte, mesurée par les différences importantes dans de fréquences des allozymes entre populations sympatriques sur plusieurs plantes-hôtes, a été examinée dans quatre régions. Il apparaît ainsi que la formation de races en fonction de l'hôte se produit chez Y. padellus et que la spéciation sympatrique est un évènement très vraisemblable.
    Notes: Abstract The amount of genetic differentiation at various levels of evolutionary divergence (conspecific populations, sibling species and non-sibling species) in Yponomeuta was determined. Genetic distances between siblings or non-siblings were found to cover a wide range. It is concluded that such estimates do not give much information on the speciation process itself. Inbreeding coefficients were calculated for populations of Y. padellus from a total of six host plants. The grand mean F ST value is 0.030±0.012. F ST values for populations sampled from Crataegus, the common food plant of Y. padellus, are 2–3.5 times smaller than those for populations from the other food plants taken together. Host race formation, as measured by significant differences in allozyme frequencies between sympatric populations on two or more food plants, was investigated in four areas. Host race formation seems to occur in Y. padellus and sympatric speciation is a likely event.
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  • 9
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    Entomologia experimentalis et applicata 34 (1983), S. 20-26 
    ISSN: 1570-7458
    Keywords: Dioryctria abietella ; Cone pyralid ; Lepidoptera ; Pyralidae ; Sex pheromone, (Z,E)-9,11-tetradecadienyl acetate ; Single sensillum recordings ; Electroantennography ; Gas chromatography ; Mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'analyse en chromatographie gazeuse associée à une détection électroantennographique a montré que l'acétate (Z,E)-9,11-tétradécadiényle (Z,E)-9,11–14:Ac est l'un des composants de la phéromone de Dioryctria abietella Schiff (Lepid.: Pyralidae). Couplage chromatographie en phase gazeuse spectrometrie de masse a montré la présence d'acétate tétradécadiényle avec un spectre de masse et un indice de rétention identiques au Z,E-9,11–14:Ac Un récepteur cellulaire sensible à la fois au Z,E-9,11–14:Ac et à un extrait de la femelle a été identifié sous l'antenne du mâle. Les analyses des antennogrammes et de la cellule isolée ont étayé la caractérisation du composant de la phéromone comme étant Z,E-9,11–14:Ac. Un récepteur cellulaire additionnel sensible à l'acétate (Z.)-9-tétradécadiényle et à l'acétate (Z.E.)-9,12-tétradécadiényle a été trouvé sur l'antenne du mâle, mais il n'était pas activé par l'extrait de la femelle. Sur le terrain Z,E-9,11–14:Ac, présenté seul, attirait des nombres importants de mâles de D. abietella. L'addition de l'acétate (Z)-9-tétradécényle a inhibé l'attraction des mâles par les pièges.
    Notes: Summary Gas chromatographic analyses coupled with electro-antennographic detection indicated that (Z,E)-9,11-tetradecadienyl acetate (Z,E-9, 11–14:Ac) is a pheromone component of the cone pyralid Dioryctria abietella. Gas chromatographic-mass spectrometric analyses confirmed the presence of a tetradecadienyl acetate with mass spectrum and retention index identical to Z,E-9,11–14:Ac. A receptor cell sensitive to both Z,E-9,11–14:Ac and the female extract was identified on the male antenna. An additional receptor cell sensitive to (Z)-9-tetradecenyl acetate and (Z,E)-9,12-tetradecadienyl acetate was found on the male antenna but was not activated by the female extract. In the field Z,E-9,11–14:Ac presented alone attracted significant numbers of male D. abietella. Addition of (Z)-9-tetradecenyl acetate inhibited the attraction of males to traps.
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  • 10
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    Entomologia experimentalis et applicata 36 (1984), S. 15-16 
    ISSN: 1570-7458
    Keywords: sex attractants ; Lepidoptera ; Noctuidae ; Orthosia incerta ; Orthosia cruda ; fruit pest ; Z9-14:Ac ; Z9-14:Ald ; Z11-16:Ac ; Z11-16:Ald
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 11
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    Entomologia experimentalis et applicata 34 (1983), S. 65-70 
    ISSN: 1570-7458
    Keywords: Insect growth regulators ; Anti-juvenile hormone ; Fluoromevalonate ; Precocious metamorphosis ; Premature pupation ; Ecdysis ; Fall webworm ; Hyphantria cunea ; Lepidoptera ; Arctiidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Fluormevalosäure (FMev), bekannt als ein spezifischer Inhibitor der Biosynthese des Juvenilhormons (JH) in Insekten, wurde in 0,1–50 μg/Tier Dosis topikal an 3., 4. und 5. Larvenstadien von Hyphantria cunea getestet. Die Raupen wurden auf einem semi-synthetischen, künstlichen Nährboden bei 25° und unter Langtagsbedingungen (18 : 6 St., Licht/Dunkel) gezüchtet. Diese Verbindung rief drei verschiedene Typen spezifischer Reaktionen hervor: 1) verfrühte Metamorphose, 2) gehemmte Häutung und 3) verlängerte Larvenentwicklung. Vor der verfrühten Verpuppung wurde normales Verhalten beobachtet. Die Larven des 3. oder 4. Stadiums häuteten sich meist erst nach einem interkalaren Larvenstadium in verfrühte Puppen. Unter den drei Larvenstadien erwies sich das 5. Stadium gegen die Anti-JH-Verbindung am empfindlichsten. In allen getesteten Entwicklungsphasen wiesen die frisch gehäuteten Larven die höchste Empfindlichkeit gegen FMev auf. Nach der Häutung wurde stufenweises Absinken der FMev-Empfindlichkeit beobachtet, im 5. Larvenstadium verursachte die Verbindung jedoch selbst am letzten Tag des Wachstums zu einen relativ hohen Prozentzahl verfrühte Verpuppung. Eine zweite typische Wirkung von FMev war die Hemmung der Häutungsprozesse. Zwei grundlegende Stufen der Häutungsstörungen unterschieden sich voneinander: 1) Als Folge der Anwendung hoher Dosen von FMev konnte die Mehrzahl der Raupen die alte Larvenkutikula nicht öffnen und ging deswegen in kurzer Zeit zugrunde. 2) Bei Behandlung mit niedrigen Dosen der Anti-JH-Verbindung häuteten sich einige Hyphantria-Larven scheinbar normal; nach der Häutung waren aber alle unfähig, die normalen Bewegungen und die Nahrungsaufnahme fortzusetzen. Auch die vorzeitigen Puppenhäutungen wurden in meisten Fällen durch die Anti-JH-Behandlung gehemmt. Die morphogenetischen Wirkungen von FMev konnten durch eine topikale Behandlung mit Hydroprene, einem hochaktiven JH-Analogen, vollständig oder teilweise verhindert werden.
    Notes: Summary Fluoromevalonate (FMev, ZR-3516) known as an inhibitor of JH biosynthesis was topically applied in 0.1 to 50 μg/specimen doses to the 3rd, 4th, and 5th instar caterpillars of Hyphantria cunea Drury. The anti-JH compound induced 3 main types of specific responses: 1) precocious metamorphosis, 2) inhibition of ecdysis, and 3) prolongation of larval development. Precocious pupation was accompanied by behavioural events typical of normal pupation. Third and 4th instar larvae metamorphosed prematurely mostly with the intervention of an intercalary larval instar. The 5th instar exhibited the highest sensitivity to the anti-JH agent. Within each larval stage the freshly moulted insects proved to be the most susceptible to FMev. Afterwards, the incidence of morphogenetic reaction gradually decreased with age. In another fraction of Hyphantria larvae not responding with precocious pupation, FMev evoked varying degrees of ecdysial disturbance which always resulted in the death of caterpillars. In most cases the anti-JH compound inhibited the premature pupal moult, too, and these affected insects died as tanned pharate pupae. A complete or partial “rescue” from the effects of FMev was elicited, if simultaneously or subsequently, a single topical dose of a JH analogue, hydroprene was also administered.
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  • 12
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    Entomologia experimentalis et applicata 30 (1981), S. 123-127 
    ISSN: 1570-7458
    Keywords: Sex Pheromones ; Repellent ; Heliothis armigera ; Heliothis zea ; Lepidoptera ; Noctuidae ; cotton bollworm ; corn earworm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'examen en olfactomètre a porté sur les réactions face à d'autres femelles de la même espèce, de femelles vierges ou ayant copulé d'Heliothis armigera Hübner et H. zea Boddie. Le lot comprenait 8 femelles, vierges ou ayant copulé en présence d'une femelle vierge ou ayant copulé. Les 4 combinaisons possibles de femelles vierges et de femelles ayant copulé ont été examinées avec 12 répétitions pour chaque espèce. Un extrait de l'extrémité de l'abdomen de femelles vierges d'une espèce a été présenté aux femelles de l'autre espèce pour examiner les possibilités de réactions interspécifiques aux phéromones. Pour chaque espèce, les réactions interspécifiques de répulsion entre femelles ont été hautement significatives par rapport aux témoins, à l'exception toutefois des réactions de femelle ayant copulé face à des femelles ayant elles aussi copulé. Les répulsions moyennes chez H. armigera et H. zea pour les 8 femelles de chaque expérience ont été: a) vierges en présence d'une vierge: 7,33 et 7,66; b) vierges en présence d'une femelles ayant copulé: 5,76 et 5,58; c) femelles ayant copulé en présence d'une vierge: 4,67 et 4,83. Les différences sont hautement significatives entre chaque paire de moyennes et entre chaque paire et le lot témoin; 3,17; 3,17; 3,42; 4,00 pour H. armigera; 3,17; 3,50; 2,83 et 3,75 pour H. zea. Les femelles vierges des deux espèces, H. armigera et H. zea ont présenté une réaction de répulsion en présence d'un extrait de l'abdomen de l'autre espèce; les répulsions moyennes étant respectivement 5,53 et 5,33 contre 3,83 et 3,58 pour le lot trémoin. On peut en conclure que ces répulsions doivent entraîner une tendance à la répartition uniforme.
    Notes: Abstract An olfactometer was used to determine the effect of pheromones released by females of the bollworms Heliothis armigera (Hübner) and H. zea (Boddie) on females of the same species. Four combinations of virgin and mated females were tested for repellency of one to the other. Evidence is presented that females of the two bollworms were repelled by females of the same species. In addition, extracts of virgin female abdomens of each species repelled virgin females of the other species.
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  • 13
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    Entomologia experimentalis et applicata 34 (1983), S. 155-162 
    ISSN: 1570-7458
    Keywords: Hymenoptera ; Braconidae ; Lepidoptera ; Nymphalidae ; Apanteles bignellii ; Euphydryas aurinia ; Multivoltinism ; Synchronisation ; Weather
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In einer Population von Euphydryas aurinia (Rottemburg) bei Oxford, England treten während einer Generation von E. aurinia drei Normalgenerationen von Apanteles bignellii Marshall auf. Jede Generation des Parasitoids kann charakterisiert werden durch das befallende Wirtsstadium und durch die aus einem Wirt schlüpfende Zahl Parasitoide. Parasitoide schlüpfen in Normalgenerationen aus dem 3., dem 4. und dem 6. Stadium des Wirts; in Ausnahmegenerationen schlüpfen sie aus dem 2. und 5. Stadium. Bis zu 70 Parasitoide können aus einer Altraupe (6. Stadium) schlüpfen und die Dauer dieses Stadiums kann bis auf 2 Wochen verlängert werden. Die Ausnahmegenerationen von A. bignellii aus Zweitlarven dürften aus Eiablagen in frühe Erstlarven stammen. Fünftlarven des Wirts, aus denen Parasitoide schlüpfen, sind ungewöhnlich klein und fressen nicht; sie dürften das Resultat sein eines Uebermasses von Apenteles-Eiern, die in frühe Viertlarven gelegt wurden. Die Synchronisation zwischen dem Parasitoiden und dem Wirt während der Zeit, da E. aurinia im Puppen-, Adult- oder Eistadium ist, wird aufrechterhalten durch ein verlängertes Coconstadium von Apanteles. Die Puppen des Parasitoiden entwickeln sich normal und die Adulten schlüpfen, bleiben aber bis 4 Wochen lang im Cocon, bevor sie sich eine Ausgangsöffnung machen. Das Wetter kann den Parasitierungsgrad der letzten Wirtsstadien beeinflussen. Wenn der Frühling kalt ist mit klarem Himmel, kann die Synchronisierung zwischen Parasitoiden, die aus Viertlarven des Wirts schlüpfen und potentiellen Fünft- und Sechtstlarven des Wirts schlecht werden. Die Entwicklung von Apanteles-Puppen wird durch die Umgebungstemperatur beeinflusst, während E. aurinia-Larven ihre Temperatur erhöhen, indem sie sich sonnen und deshalb rasch wachsen. Wenn die Parasitoiden unter solchen Bedingungen schlüpfen, sind die meisten potentiellen Wirte schon verpuppt und damit nicht mehr geeignet für die Parasitierung. Die Mechanismen der Synchronisation und der Wettereinfluss auf diese Vorgänge wird diskutiert.
    Notes: Abstract The gregarious endoparasite, Apanteles bignellii Marshall is specific to the nymphalid butterfly, Euphydryas aurinia (Rottemburg) in the British Isles. The synchronisation between host and parasitoid is described at a site near Oxford, England where both occur. Three regular generations of A. bignellii occur in one generation of the host in the studied population. Relevant features of the biology of A. bignellii and E. aurinia are described, including a method of distinguishing the number of Apanteles larval instars based upon shed cuticle remnants. Mechanisms for host-parasitoid synchronisation are outlined, especially a protracted parasitoid cocoon stage when the host is unavailable for attack during the chrysalis, adult and egg stages. Cool, but sunny weather conditions in spring can influence the degree of parasitisation experienced by final instar host caterpillars. The timing of adult A. bignellii emergence and subsequent attack on early instar hosts can lead to additional, partial, generations of parasitoids from second and fifth instar hosts.
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  • 14
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    Entomologia experimentalis et applicata 35 (1984), S. 159-167 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Geometridae ; Ectropis excursaria ; larval dispersal ; colour polymorphism ; phototaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Acht Experimente wurden durchgeführt, um einige der Faktoren zu studieren, die das Wanderverhalten der Larven (Raupen) eines polyphagen Geometriden (Ectropis excursaria (Guenée)) beein-flussen. 1. Larven sind positiv phototaktisch. Die positive Phototaxis ist negativ mit Fasten, Alter und Populationsdichte korreliert. Bei hohen Temperaturen ist sie nicht mehr nachweisbar. 2. Das Wanderverhalten der Larven wird durch die Populationsdichte beeinflußt, wodurch annähernd eine konstante Dichte erhalten bleibt. Das Verhalten der individuellen Larven is dabei nicht statistisch homogen. Es gibt ‘Wanderer’ und ‘Nicht-Wanderer’. 3. Diese Verhaltensunderschiede stehen möglicherweise im Zusammenhang mit physiologischen und morphologischen Faktoren, die den individuellen Fortpflanzungserfolg und das überleben beeinflussen können; ‘Wanderer’ sind dunkler, entwickeln sich schneller und das Gewicht ihrer Puppen ist niedriger als das der ‘Nicht-Wanderer’. 4. Eine der larvalen Farbvarianten zeigte eine Präferenz für einen von zwei angebotenen Hintergründen.
    Notes: Abstract The dispersive behaviour of larvae of a polyphagous, wide-spread geometrid (Ectropis excursaria (Guenée)) was studied by examining responses to environmental and endogenous variables. It was found that differences in behaviour can be affected by environmental factors such as light, temperature, density, and plant background as well as some physiological and morphological features. The implications of these relationships are discussed as adaptative strategies to a varying environment.
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    Entomologia experimentalis et applicata 35 (1984), S. 177-193 
    ISSN: 1570-7458
    Keywords: induction of feeding preference ; host plants ; non-host plants ; Manduca sexta ; Sphingidae ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Vingt-deux espèces de plantes, dont 10 planteshôtes (Solanées), ont été testés comme plantes alimentaires pour des chenilles de ler stade de Manduca sexta. Sur cet ensemble, seulement 12 plantes (dont 9 plantes hôtes) induisaient la prise de nourriture et permettaient la croissance jusqu'au 5ème stade. La diversité des résultats suggère que les plantes pouvaient être classées en hôtes, non-hôtes acceptables et non-hôtes refusés. En utilisant le test du choix alimentaire préférentiel entre deux rondelles de feuilles, les chenilles néonates de ler stade ont préféré nettement les plantes-hôtes aux autres. Cette préférence initiale pour les plantes-hôtes était préservée quand les cheniles étaient élevées sur plantes-hôtes, mais devenait moins nette ou disparaissait pour des chenilles élevées sur d'autres plantes acceptées. Ainsi l'oligophagie ches M. sexta n'est pas induite, mais doit être héritée. Les chenilles néonates, aussi bien que celles de 5ème stade, présentent des préférences hiérarchisées parmi les plantes hôtes ou non. La seule frontiere nette observée était entre espèces de plantes acceptables ou non. Les hiérarchies préférentielles des chenilles du 5ème stade différaient légèrement lors-qu'elles avaient été élevées sur deux plantes-hôtes différentes. La différence essentielle était l'observation d'une préférence accrue pour l'espèce ayant servi à l'élevage, mais deux autres plantes-hôtes changaient aussi de position hiérarchique. La cause de ces changements de préférence a été approfondie, les chenilles étant élevées sur des feuilles de chaque espèce acceptable (hôte ou non). Leurs préférences alimentaires ont été définies en utilisant des combinaisons diverses (hôte x hôte, hôte x non-hôte acceptable, non-hôte acceptable x non-hôte acceptable). L'induction de la préférence alimentaires a été obtenue dans ces trois associations. Ceci montre que l'induction des choix alimentaires chez M. sexta n'est pas limitée aux plantes-hôtes. Le degré d'induction de la préférence alimentaire variait de très fort à indécelable; il dépendait de l'association examinée. La source de la variabilité de cette induction a été examinée en fonction de la relation entre la force de l'induction et les rapports taxonomiques des plantes associées. La relation obervée était inversée pour M. sexta. L'examen des données de la littérature ont révélé une relation du même type pour les autres espèces de Lépidoptères.
    Notes: Abstract Ten host plant (Solanaceae) and twelve non-host plant species were tested as foodplants for first instar larvae of the tobacco hornworm, Manduca sexta. Only nine host and three non-host plant species elicited feeding and supported growth up to fifth instar. The range of acceptability suggested that plants be divided into hosts, acceptable non-hosts, and unacceptable non-hosts. Using the two-choice feeding preference test we found that the initial preference for hosts was preserved when larvae were reared on hosts, but was less strong or absent for larvae reared on acceptable non-hosts. Thus oligophagy in the tobacco hornworm is not induced, but must be inherited. Newly-hatched first instar larvae and fifth instar larvae showed a preference hierarchy among both hosts and non-hosts. Fifth instar larvae reared separately on two different host species showed slightly different preference hierarchies among hosts. The preference for the rearing plant was increased and also two other host species changed positions in hierarchies. Feeding preferences of larvae reared on hosts or acceptable non-hosts were determined using plant combinations of host vs. host, host vs. acceptable non-host, and acceptable non-host vs. acceptable non-host. Induction of feeding preference was found in all three of these categories. This shows that induction of feeding preference in the tobacco hornworm is not restricted to host plant species. The degree to which feeding preferences were induced ranged from very strong to undetectable and dependend on the plant species paired. The strength of induction in the tobacco hornworm was found to correlate inversely with taxonomic relatedness of the plant species paired. Analysis of induction data from the literature revealed a similar correlation for other lepidopteran species.
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    Entomologia experimentalis et applicata 35 (1984), S. 255-261 
    ISSN: 1570-7458
    Keywords: method ; dry matter ; budget ; Lepidoptera ; phytophagous ; gravimetry ; area ; accuracy ; precision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les budgets en matière sèche consommée par des lépidoptères ont été comparés par les méthodes gravimétrique et planimétrique. La méthode gravimétrique est basée sur le rapport poids sec/poids frais de feuilles consommées par les chenilles. Avec la méthode planimétrique, la quantité d'aliment proposée aux chenilles est déterminée par les tracés de la surface des feuilles et le contenu de matière sèche par unité de surface des feuilles. La méthode de planimétrie permet l'utilisation de plus grands rameaux de feuilles et de cages d'élevage extérieures en gaze. Il n'y avait pas de différence appréciable dans les éléments du budget (croissance, ingestion et déjection), ni aucune différence dans la variabilité observée des données attribuable à la méthode utilisée. Cependant, la variabilité attendue d'après la précision des mesures avec la méthode gravimétrique est inférieure à celle de la méthode planimétrique. est inférieure à celle de la méthode planimétrique. Des éléments expérimentaux, inhérents à la méthode gravimétrique, introduisent une variabilité dans les mesures que l'on n'a pas avec la méthode planimétrique. 30–60% de la variabilité dans la consommation ont été attribués à des paramètres internes à la chenille, même quand elles provenaient toutes de la même ooplaque.
    Notes: Abstract Gravimetric and a combination areal-gravimetric methods for determining dry matter budgets for leaf eating Lepidoptera were compared. The gravimetric method is based on dry weight/live weight ratios of the leaves fed to the larvae. In the areal-gravimetric method, the quantity of food offered to the larvae is determined from the area of leaf tracings and the dry matter content per unit area of the leaves. The areal-gravimetric method permits the use of larger leaf sprays and an open, gauze enclosed rearing chamber. There were no consistent differences in budget factors (growth, ingestion or egestion), nor were there any differences in the observed variability of the data attributable to the method used. However, the expected variability based on instrument precision for the gravimetric method is less than for the areal-gravimetric method. Experimental factors inherent in the gravimetric method introduce variability to the measurements that are not present in the areal method. Thirty to 60% of the variability in budget factors was attributed to intrinsic properties of the larvae, even though the larvae were taken from the same egg masses.
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    Entomologia experimentalis et applicata 34 (1983), S. 121-122 
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Noctuidae ; Earias insulana ; Bollworm ; Artificial diets ; Insect fecundity
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  • 18
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    Calcified tissue international 33 (1981), S. 409-416 
    ISSN: 1432-0827
    Keywords: Bone Cells ; Cyclic AMP ; Calcium ; Parathyroid hormone ; Prostaglandin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have examined the influence of extracellular Ca2+ on cyclic AMP metabolism in an osteoblast-enriched population of bone cells isolated from the calvaria of rat fetuses. The cyclic AMP1 response to stimulators of cyclic AMP formation (PTH and PGE2), but not basal cyclic AMP levels, increased progressively as the extracellular Ca2+ concentration was raised from 0.2 to 4.0 mM. The response to changes in extracellular Ca2+ were rapid (within 3.5 min), and the level of responsivity that characterized each Ca2+ concentration persisted for at least 6 h when the Ca2+ concentration was kept constant. The effect of Ca2+ spanned the entire time course of PTH action, was not accompanied by altered excretion of cyclic AMP from the cells, and was evident at low as well as at high hormone concentrations. Ca2+ augmented the action of PTH in the presence as well as in the absence of cyclic AMP phosphodiesterase inhibitors, and failed to decrease cyclic AMP phosphodiesterase activity in the short term. Mn2+ and, to a smaller degree, Ba2+ substituted for Ca2+ in promoting the cyclic AMP response to PTH. Verapamil, an inhibitor of Ca2+ penetration, blunted the Ca2+-mediated increments in the cyclic AMP response, and the divalent cation ionophore A23187 enhanced these increments. These results indicate that Ca2+ and other cations are positive effectors of the stimulated cyclic AMP response in isolated bone cells. Accumulation into an as yet unknown cellular compartment may be required for the cation effect. The data are most consistent with enhancement of adenylate cyclase reactivity as the mode of cation action.
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  • 19
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    Calcified tissue international 25 (1978), S. 217-222 
    ISSN: 1432-0827
    Keywords: Bone mineral ; Electron microscopy ; X-ray diffraction ; Dark field
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    Topics: Biology , Medicine , Physics
    Notes: Summary Electron microscopical observations of the size and shape of bone mineral crystallites have not been in complete agreement with X-ray diffraction findings. The two prevalent viewpoints consider bone mineral crystals to be either rod, or plate like in habit. There appears to be agreement that the smallest dimension of the crystals is about 5 nm, but there is discrepancy in the reported c-axial lengths. The method of dark field imaging is used to obtain a quantitative measurement of the c-axial length distribution in rabbit, ox and human bone: mean c-axial lengths 32.6 nm, 36.2 nm and 32.4 nm, respectively, show no significant difference at the 5% level to the mean c-axial length measured by X-ray line broadening. Both bright and dark field images strongly suggest that bone mineral has a plate like form. Reasons for past discrepancies are discussed.
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    Calcified tissue international 27 (1979), S. 205-210 
    ISSN: 1432-0827
    Keywords: Intestine ; Calcium ; Binding ; Protein ; Uremia
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    Topics: Biology , Medicine , Physics
    Notes: Summary In order to assess the usefulness of intestinal biopsies as indicators of end-organ responsiveness to vitamin D in uremic patients, calcium binding activity and calcium binding protein (CaBP) content were measured in intestinal biopsies from 12 uremic patients (glomerular filtration rate〈5.0 ml/min) and 12 adult controls. Values for both were found to vary with the site of biopsy, highest values being obtained in the duodenal bulb, with lower values distally. Values for activity correlated with values for CaBP content in both normals and uremics and no difference was observed between groups. Levels of calcium binding activity and content of CaBP did not correlate with serum immunoreactive parathormone levels, but were directly related to circulating 25-hydroxycholecalciferol (25-OHD) levels. The data show that intestinal CaBP is normal in activity, quantity, and affinity for calcium in malabsorbing uremic patients, and are consistent with the hypothesis that calcium malabsorption in uremia is unrelated to deficiency of intestinal calcium binding protein.
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    Calcified tissue international 24 (1977), S. 173-177 
    ISSN: 1432-0827
    Keywords: Enamel ; Calcium ; Diffusion
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    Topics: Biology , Medicine , Physics
    Notes: Summary The diffusion of45Ca ions in sound bovine enamel at pH 7.0 was studied as a function of temperature in the range 20°–40°C. The experimental data show that the diffusion is governed by two processes with activation energies of about 0.7 and 1.3 eV respectively. These values are considerably larger than the activation energy of calcium ion diffusion in water (0.2 eV). The diffusion process with the activation energy of 1.3 eV is dependent upon the calcium concentration in solution. A model based on the complex pore structure of enamel and on interactions of diffusing ions with the enamel constituents is discussed.
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    Calcified tissue international 28 (1979), S. 131-136 
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Citrate ; Precipitation
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    Topics: Biology , Medicine , Physics
    Notes: Summary The influence of citrate ions on the precipitation of crystalline apatitic precipitates with low Ca/P molar ratios [octacalcium phosphate (OCP) and calcium-deficient apatites (DA) (system A)] and of the intercrystalline mixtures of calcium hydrogen phosphate dihydrate (DCPD) and DA (system B) was investigated. Samples were prepared by direct mixing of calcium chloride solutions (A, 6·10−3 mol dm−3; B, 1·10−1 mol dm−3) and sodium phosphate solutions (A, 6·10−3 mol dm−3; B, 2·10−2 mol dm−3) containing citrate (0–2·10−3 mol dm−3) and preadjusted to pH 7.4. In the presence of citrate ions: (a) crystal growth of OCP and DA was slowed down; (b) habit modification of DCPD crystals occurred; and (c) equilibration in intercrystalline mixtures of DCPD and DA's was slowed down. All phenomena were caused by surface adsorption of negatively charged ions, most probably CaC6H5O7-, which is the prevalent calcium citrate species under the given experimental conditions. Habit modification of DCPD was induced by preferential adsorption at the (001) crystal plane.
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  • 23
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Osteoclasts ; Electron microscopy ; Morphometry ; Metaphysis
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    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of parathyroid hormone (PTH) on the size of the osteoclasts, nuclei, ruffled borders, and clear zones in long bones of thyroparathyroidectomized (TPTX) rats were quantitated as a function of time. These data were compared with the number of osteoclasts in the bone and with plasma calcium levels. A significant increase in the average size of the ruffled borders was demonstrated 30 min after injection of 50 U of purified bovine PTH, and of the clear zones 30–90 min after PTH. This was followed at 90 min by an increase in the average size of the cells. The sizes of ruffled borders and clear zones dropped sharply to control levels after 6 h, whereas the size of the cells remained elevated up to 12 h and returned to control values at 24 h. Plasma calcium levels were increased, but not significantly, between 30 min and 6 h. An increase in the number of osteoclasts was significant after 12 h. Removal of the parathyroid glands did not diminish the normal activity of osteoclasts. In animals with intact glands injection of 50 U of PTH did not cause a significant change in cell size or resorbing apparatus. It is concluded that PTH acts to rapidly stimulate the bone resorptive activity of osteoclasts and to cause a delayed increase in their number.
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    Calcified tissue international 30 (1980), S. 209-216 
    ISSN: 1432-0827
    Keywords: Calvarium ; cAMP ; Vitamin D3 metabolites ; Calcium ; Parathyroid hormone
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    Topics: Biology , Medicine , Physics
    Notes: Summary Results from in vitro works suggest that 1,25- and 24,25-dihydroxyvitamin D3 (1,25-(OH)2D3 and 24,25-(OH)2D3) act on bone via different mechanisms. The present investigation was performed to study the effect of these two metabolites and of their precursor 25-hyxdroxyvitamin D3 (25-(OH)D3) on bone cAMP content in vitro. Rats' paired half calvaria were incubated under sterile conditions with one vitamin D3 derivative (10−13 to 10−9 M) or with ethanol (0.005 ml for 15 min to 24 h in 1 ml medium containing 0, 0.2, 1, 2, or 3 mM calcium. In some experiments: (a) cycloheximide (10−5M) was added simultaneously with the vitamin D3 metabolites; (b) 1–84 bPTH (5 × 10−8 M) was added for 5 or 15 min at the end of the 24 h incubation. Calvaria were immersed in 1 ml TCA 5% 4°C and homogenized. The cAMP was extracted with diethylether and measured by a competitive protein binding assay. Results bring further evidence for a particular effect of low doses of 24,25-(OH)2D3 (10−9 to 10−12M) and of 25-(OH)D3 (10−9 to 10−11M) on bone, different from that of 1,25-(OH)2D3: cAMP content was higher in 24,25-(OH)2D3- or 25-(OH)D3-treated and lower in 1,25-(OH)2D3-treated calvaria than in ethanol-treated ones with 1 mM calcium. The 1,25-(OH)2D3 effect persisted in calcium-free medium whereas 25-(OH)D3 and 24,25-(OH)2D3 effects could not be observed with 0 mM nor with 3 mM calcium. The required duration of the preincubation (over 1 h) as well as the inhibitory action of cycloheximide may suggest an involvement of protein synthesis in the vitamin D3 metabolites effects. Neither 1,25-(OH)2D3 nor 24,25-(OH)2D3 affected the PTH-induced increase in bone cAMP content.
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    Calcified tissue international 32 (1980), S. 201-206 
    ISSN: 1432-0827
    Keywords: Magnesium ; Parathyroid hormone ; Secretion ; In vitro ; Calcium
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    Topics: Biology , Medicine , Physics
    Notes: Summary In a well-defined in vitro perifusion system, the effects of extracellular magnesium concentration (Mg) on parathyroid hormone (PTH) secretion by bovine parathyroid tissue were examined. At Mg less than 0.8 mM, the ability of the glands to secrete hormone maximally in response to low calcium (Ca) stimulation was progressively impaired. Low Mg also impaired the ability of isoproterenol, dibutyryl cyclic AMP and theophylline to stimulate hormone release. The defect in hormone release at low Mg observed in vitro was analogous to the well-documented inhibition of secretion observed in vivo. Increases in Mg from 0 to 0.8 mM rapidly repaired the defect in hormone secretion. At Mg above 1.0 mM there was a Ca-like effect on hormone release, with a progressive decrease in secretion at increased Mg. Although its mechanism is not yet clear, the low Mg effect appears to impair principally the process of hormone release rather than its biosynthesis or storage.
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    Calcified tissue international 36 (1984), S. 139-144 
    ISSN: 1432-0827
    Keywords: 1,25(OH)2-vitamin D ; Weight loss ; Phosphate ; Calcium
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    Topics: Biology , Medicine , Physics
    Notes: Summary During a review of 42 metabolic studies in healthy women and men we observed that serum 1,25-(OH)2-D concentrations were directly correlated to the observed daily changes in body weight (r=0.68;P〈0.001) and to caloric intake/kg/day (r=0.39;P=0.01). These relationships could not be accounted for by related and physiologically expected changes in serum Ca or iPTH concentrations. However, serum 1,25-(OH)2-D concentrations were observed to be inversely correlated to serum PO4 levels (r=−0.44;P=0.004). In addition, serum PO4 levels were inversely correlated to the daily changes in body weight (r=−0.40;P=0.009). Since dietary sodium intake averaged 142 mmol/day, it is unlikely that the observed changes in weight were the result of changes in salt and water balance. Thus it seems reasonable to speculate that serum 1,25-(OH)2-D concentrations may vary directly with energy balance, as reflected by changes in body weight. This effect may be mediated by alterations in PO4 metabolism. The accurate assessment of serum 1,25-(OH)2-D levels thus appears to require several measurements over time periods during which body weight is stable.
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  • 27
    ISSN: 1432-0827
    Keywords: Electromagnetic field ; Bicarbonate ; Phosphate ; Calcium ; Fluoride ; Osteogenesis
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    Topics: Biology , Medicine , Physics
    Notes: Summary The present studies are aimed at establishing molecular correlations in the interaction of very low frequency electromagnetic fields with biological systems. Ca-uptake by chick embryo tibia rudiment in short-term culture was a useful model. Tibiae of 8- to 10-day-old chick embryos were incubated 60 min in simplified culture media in the presence of45Ca at 37.5±0.5°C either inside or outside pulsating electromagnetic fields. Radioactivity count in the medium was the most accurate method for determining Ca-uptake by the rudiment. The effect of the fields on the Ca-uptake depended markedly on the chemical composition of the culture medium: bicarbonate was indispensable; glucose or sucrose was important; phosphate was potentiating; ethanol, Mg2+, and NaF were stimulating. The field had no effect in (a) blank medium without tibia, (b) tibiae that had been altered by fixation with aqueous glutaraldehyde, (c) nonliving artificial systems endowed with great or small ion sorption capacity. The unique bicarbonate effect with living systems and the passive behavior of nonliving ion sorbing systems prompt the suggestion that the electromagnetic field probably couples with specific processes, such as a bicarbonate-dependent Ca2+ ATPase and the active ion transport, at the cell membrane level. The molecular mechanisms remain to be established.
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    Calcified tissue international 36 (1984), S. 194-199 
    ISSN: 1432-0827
    Keywords: Benzo(B)Thiophene-2-Carboxylic Acid ; Bone cells ; Calcium ; Cyclic AMP
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    Topics: Biology , Medicine , Physics
    Notes: Summary The purpose of the present study was to investigate the mechanism of action on bone of Benzo(B)Thiophene-2-Carboxylic Acid (BL-5583). BL-5583, at a dose range of 0.01–100 µg/ml, inhibited spontaneous as well as A23187 and PTH-induced bone resorption in tissue culture. This compound also decreased calcium uptake in both osteoclastic and osteoblastic enriched bone cell populations obtained by sequential collagenase digestion of 1–2 day newborn rat calvariae. The decrease occurred after a 5 min. incubation with45Ca and BL-5583. The effective dose range was 0.01–100 µg/ml. No effect on leucine incorporation or lactic acid production by bone cells was observed. BL-5583 also induced a transient decrease in calcium uptake in skin cells isolated from fetal rats by collagenase digestion, suggesting a lack of tissue specificity for this compound. No effect on cyclic AMP in isolated bone cells was observed with the same dose range that produced a calcium effect.
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  • 29
    ISSN: 1432-0827
    Keywords: Saliva ; Calcium ; Phosphate ; Ion-binding ; Supersaturation
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    Notes: Summary Previous ultrafiltration studies indicated that up to one-half of the calcium and two-thirds of the phosphate in human salivary secretions may be bound by salivary proteins. Since this binding is an important variable in determining the extent of salivary supersaturation with respect to calcium phosphate salts, and since the amount of binding reported is surprisingly large, calcium and phosphate ion-binding by salivary macromolecules has been reexamined. From experiments using equilibrium dialysis, it was found that (1) the fraction of salivary calcium involved in macromolecular complexes ranges from a few percent for unstimulated secretions, to no more than about 10% for stimulated glandular salivas, and (2) salivary proteins do not bind phosphate ions to any significant extent. These findings, and experiments using an improved ultrafiltration membrane, indicate that the earlier results were artifacts of the ultrafiltration technique. Fractionation of salivary proteins, followed by equilibrium dialysis measurements, showed that the anionic proline-rich proteins and a basic proline-rich glycoprotein are responsible for most of the calcium binding now observed. The finding that macromolecular complexes of salivary calcium and phosphate have been overestimated in the past, leads to the conclusion that salivary calcium and phosphate ion activities in stimulated salivary secretions may be up to 50 to 100% higher than previously thought. Revised values were therefore used to recalculate the degree of salivary supersaturation with respect to calcium phosphate salts. The results indicate that stimulated salivary secretions are supersaturated with respect to dicalcium phosphate dihydrate; this is a substantially greater degree of supersaturation than previously reported.
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  • 30
    ISSN: 1432-1432
    Keywords: Lysozyme ; Insect ; Lepidoptera ; Evolution ; Sequence
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    Topics: Biology
    Notes: Summary Sequence studies of the N-terminal halves of the lysozymes isolated fromBombyx mori, Galleria mellonella andSpodoptera littoralis (Lepidoptera) allow us to classify these enzymes among the c (chicken) type lysozymes.
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    Mycopathologia 60 (1977), S. 175-177 
    ISSN: 1573-0832
    Keywords: Aspergillus fumigatus ; Spore formation ; Electron microscopy
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    Mycopathologia 61 (1977), S. 117-119 
    ISSN: 1573-0832
    Keywords: Prototheca ; Colorless alga ; Plastids ; Electron microscopy
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    Topics: Biology , Medicine
    Notes: Abstract An ultrastructural investigation of six different species of Prototheca showed that all of them contained starch grains enclosed in double-membrane-bounded structures recognized as plastids. It is concluded that these unicellular species of Prototheca must be considered as non-photosynthetic algae.
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    ISSN: 1573-0832
    Keywords: Trichophyton mentagrophytes ; Thiocyanatopyrazole derivatives ; Electron microscopy
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    Notes: Abstract Four thiocyanatopyrazole derivatives were synthesized and their fungistatic activity was demonstrated in vitro against a number of dermatophytic fungi. In Trichophyton mentagrophytes, the most active compound induced an unusual increase of the plasma membrane with production of intra and extracytoplasmic complexes, a deterioration of nuclear and mitochondrial membranes and a formation of autophagic-like vacuoles. Plasmolysis, accompanied by an almost complete disorganization of cytoplasmic structures, seemed to be the final event. A possible mechanism of action of the compounds was discussed.
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    Applied physics 8 (1975), S. 319-331 
    ISSN: 1432-0630
    Keywords: Self-interstitials in silicon ; Swirls ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Point defect agglomerates in dislocation-free silicon crystals, usually called “swirls”, have been investigated by means of high-voltage electron microscopy. It was found that a single swirl defect consists of a dislocation loop or a cluster of dislocation loops. By contrast experiments it could be shown that these loops are formed by agglomeration of self-interstitial atoms. Generally the loops have a/2〈110〉 Burgers vectors, but in specimens with high concentrations of carbon (∼1017 cm−3) and oxygen (∼1016 cm−3) also dislocation loops including a stacking fault were observed. In crystals grown at growth rates higher thanv=4 mm/min no swirls are observed; lower growth rates do not markedly affect the size and shape of the dislocation loops. With decreasing impurity content (particulary of oxygen and carbon) the swirl density decreases, whereas the dislocation loop clusters become larger and more complex. A model is presented which describes the formation of swirls in terms of agglomeration of silicon self-interstitials and impurity atoms.
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  • 35
    ISSN: 1432-041X
    Keywords: Lepidoptera ; Male genital disk ; Implantation ; Regeneration ; Control of metamorphosis
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    Topics: Biology
    Notes: Summary Complete and bisected male genital disks (HO) from full-grown (T9) larvae were transplanted either into larvae and pharate pupae of different age (T4, T7, T9 larvae, A1–A5 pharate pupae) or repeatedly transferred into full-grown larvae before being implanted into a final larval host. After metamorphosis of the hosts, most of the complete transplants and regenerated HO halves showed normal morphological features, but the implanted genitals from old pharate pupae (A4 and A5) were abnormally differentiated. Frequency of Regeneration. After transplanting both halves of the bisected HO into T9 hosts, three groups of results were observed: (1) each of the two halves regenerated into a complete genital organ; (2) only one half regenerated; (3) neither of the two halves regenerated. In the pharate pupae no regeneration of the implanted halves took place. If the lapse of time between the transplantation and, the onset of metamorphosis (=onset of pharate pupae phase) was long enough by transplanting into young larvae (T4) or by repeatedly transferring into old larvae and subsequent transplantation into a final larval host, all the implanted halves were able to regenerate. Size of the Implanted Genital Organs After prolonging the in vivo culture in larval hosts by implanting into young larvae or repeatedly transferring into old larvae, it was found that the regenerated genitalia grew to the same size as the complete transplants, but the size of the complete transplants increased, if at all, only insignificantly. Duration of Development of the Hosts. Regeneration of one HO half implanted into a full-grown larva caused an average delay of further development of about 2 days. An additional delay was recorded when both halves had regenerated. However, no delay was observed when HO halves implanted into young (T4) larvae regenerated, and no delay occurred in the final hosts when the repeatedly transferred halves had reached a certain stage of regeneration. The developmental capacities of the tranplanted disks and the control of metamorphosis by regenerating disks are discussed.
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  • 36
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    Development genes and evolution 191 (1982), S. 205-207 
    ISSN: 1432-041X
    Keywords: Chitin inhibition ; Nikkomycin ; Cuticle ; Electron microscopy ; Epilachna varivestis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleoside antibiotic nikkomycin has proved to be an effective inhibitor of chitin synthesis in the Mexican bean beetleEpilachna varivestis. Ultrastructural investigations show defects in the procuticular area after nikkomycin application which suggest the complete absence of chitin. A cuticle like this is inflexible and too brittle to satisfy its normal function as an exoskeleton. The individuals are not able to free themselves from the exuvia and finally die. Therefore nikkomycin seems to be a potential insecticide with high specifity.
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  • 37
    ISSN: 1432-041X
    Keywords: Synaptogenesis ; Electron microscopy ; Visual acuity ; Fish development
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    Topics: Biology
    Notes: Summary The morphogenetic differentiation of synapses of the optic tectum of the rainbow trout was investigated at different stages of development (from hatching to adult) and compared with the improvement in visual discrimination (minimum separable). (1) The main phase of synaptogenesis (increase in number of synapses, length of contact zone and number of vesicles) begins about one week after hatching and continues up to the age of one month, when the larvae start swimming freely. (2) Myelination begins 26 days after hatching and induces the end of the synaptogenesis period. (3) The visual discrimination (minimum separable) of trout larvae improves from 30 degrees of arc on the 10th day after hatching to 1 degree on day 30, then to about 14 to 18 min of arc in the adult. The results are discussed with special reference to previous biochemical investigations on changes in the ganglioside composition of the trout brain during comparable periods of development.
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  • 38
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    Calcified tissue international 33 (1981), S. 143-151 
    ISSN: 1432-0827
    Keywords: Calcium transport ; Cytochalasin B ; Dihydrocytochalasin B ; Colchicine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In vivo calcium absorption was studied in normal and rachitic chicks. Cytochalasin B (CB) at a concentration of 25 µg/ml added to the medium inside the duodenal lumen inhibited calcium absorption (20 min) from 82.5±1.9% of calcium absorbed in the controls to 59.2±3% in normal and from 70.0±2.3% to 47.0±2.1% in rachitic chicks. In vitro studies by everted ileal sacs of young rabbits also showed an inhibition of active transport of calcium due to CB. Whereas in the controls the ratio of45Ca concentrations in serosal and mucosal media (60 min) was 7.2±0.32, the ratios were 5.24±0.52; 4.40±0.36; 3.40±0.42; 5.77±0.52; 1.38±0.08; and 1.06±0.02 in the presence of CB at concentrations of 5, 10 and 25 µg/ml; colchicine 10−4M, Na citrate 0.02M, and heat-devitalized conditions, respectively.45Ca concentration in the mucosal scrapings was also affected. It showed an increase from controls (15,101±404 cpm/mg) and correlated with CB concentration: 17,378±489, 19,015±1000, and 20,201±362 at 5, 10, and 25 µg/ml, respectively. Dihydrocytochalasin B also inhibited active calcium transport and caused an increase in45Ca concentration in the mucosal scrapings. Correlated electron microscopic studies showed certain changes in the brush border, especially in some actin microfilaments in the terminal web region. It seems that these morphological alterations may be related to transcytoplasmic movement of calcium.
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  • 39
    ISSN: 1432-0827
    Keywords: Alcohol ; Electron microscopy ; Growth plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have previously demonstrated that ethanol has a direct toxic effect on the rat skeleton characterized by decreased trabecular bone volume. In the present study, we examined the ultrastructure of the distal radial epiphyseal growth plates in these same animals. Eight weeks of ethanol administration to 12 male rats results in serum alcohol levels of 140 mg/dl but did not alter the width or light microscopic appearance of the radial growth plate. Quantitative electron microscopy failed to demonstrate morphologic evidence of toxicity in the skeletal cells. We conclude that although ethanol appears to have a direct effect on rat bone characterized by enhanced resorption, toxicity is not attended by ultrastructural changes in the skeletal cells.
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  • 40
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    Calcified tissue international 33 (1981), S. 529-540 
    ISSN: 1432-0827
    Keywords: Bone cells ; Electron microscopy ; PTH ; PGE1
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    Topics: Biology , Medicine , Physics
    Notes: Summary Four different cell populations—designated PF, OB, OC, and PC—were isolated from calvaria of 18-day-old chick embryos for analysis of the effects of hormones on bone tissue. The cell populations were studied with histological and biochemical methods. Apart from the well-known cell types present in calvaria, a new cell type was found in the noncalcified organic matrix between the osteoblastic layer and the calcified matrix. These cells were provisionally called osteocytic osteoblasts. They represent the “transition state” between osteoblasts and osteocytes. On the basis of histological studies with light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), the PF population was considered to originate primarily from the periosteal fibroblasts, the OB population from the osteoblasts and osteocytic osteoblasts. The population of cells still present in calvaria after removal of periosteal fibroblasts and osteoblasts was called the OC population. This cell population was very much enriched with osteocytes. The fourth isolated population (PC) was a mixed population of fibroblasts, osteoblasts, and preosteoblasts. On exposure to parathyroid hormone (PTH), all four cell populations showed increased lactate production, but only the OB and OC populations displayed increased cAMP production. Prostaglandin E1 (PGE1) stimulated cAMP production in both OB and PF cells. From the results of this study it was concluded that PTH receptors are present on all of the cell types studied, but that occupancy of the receptor induces adenylate cyclase stimulation only in osteocytes and fully differentiated osteoblasts.
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  • 41
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    Calcified tissue international 24 (1977), S. 59-64 
    ISSN: 1432-0827
    Keywords: Enamel ; Calcium ; Exchange ; Diffusion
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    Topics: Biology , Medicine , Physics
    Notes: Summary The penetration of45Ca ions into whole bovine enamel from an aqueous solution was studied as a function of the Ca content in the solution. A sectioning technique was employed to measure the penetration of45Ca into the enamel. Probably only Ca ions occupying surface positions in the hydroxyapatite crystallites participate in the exchange process at the solution-enamel interface. The fraction of Ca ions participating in the exchange was 2% of the total number of Ca ions. Two different diffusion processes occur; firstly, a process governed by a diffusion coefficient, D1 ranging from about 5×10−14 to 2×10−12 cm2/s and strongly dependent on the calcium concentration in the solutions; and secondly a process with a concentration-independent diffusion coefficient, D2, with a value of 2.8×10−12 cm2/s. It is assumed that the 2 diffusion types correspond to intra-and interprismatic transport, respectively. A model based on the pore structure of dental enamel and on surface charges on hydroxyapatite crystallites is discussed.
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  • 42
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    Calcified tissue international 24 (1977), S. 113-117 
    ISSN: 1432-0827
    Keywords: Bone membrane ; Calcium ; Ion fluxes ; Calvarium
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    Topics: Biology , Medicine , Physics
    Notes: Summary To facilitate the study of membrane function in the control of the flow of ions into and out of bone, it was desirable to develop a system for the direct quantitation of unidirectional effluxes of calcium and phosphate from bones. Based on a mathematical analysis of the problem, a specially designed Ussing chamber was developed which proved successful. Calvaria from 2-day-old rat pups, 3-day chicks and adult mice were evaluated. Calcium influxes which exceeded the corresponding effluxes were observed in the neonatal calvaria but not with those from adult mice. Also, an asymmetry in efflux was observed in rat calvaria, the inner side of the skull showed a higher efflux than did the external side. no such asymmetry was seen with calvaria from chicks or mice. This new technology should permit a further exploration of the role of the bone membrane in electrolyte homeostasis.
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  • 43
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    Calcified tissue international 22 (1977), S. 9-17 
    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Calcium ; Phosphorus ; Mechanical Strength
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    Topics: Biology , Medicine , Physics
    Notes: Abstract Four groups of weanling rats were fed for 2 weeks on a diet sufficient or insufficient in calcium and/or phosphorus. Each group was divided into four subgroups which were offered distilled water supplemented with 0, 50, 75, or 150 ppm fluoride. High levels of fluoride in drinking water inhibited weight gain. This inhibition was less in rats deficient in phosphorus than when normal-phosphorus diets were offered. At a low level, fluoride was without any effect on bone ash, thickness of femoral cortical bone, and mechanical strength, as measured by maximal load, ultimate stress to breaking, and limit of elasticity. Modulus of elasticity was decreased. At higher levels fluoride tended to decrease most of these parameters, except in rats deprived of both calcium and phosphorus. The effect of fluoride was modified by lack of dietary calcium and/or phosphorus and appeared to be weaker in rats deficient in these nutrients. Lack of dietary calcium and/or phosphorus decreased bone strength more than did fluoride content of water and of bone mineral. Concentration of bone ash and thickness of femoral cortical bone were closely correlated with parameters of mechanical strength.
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  • 44
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    Calcified tissue international 22 (1977), S. 275-284 
    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Collagen ; Dentine ; Phosphoprotein
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    Topics: Biology , Medicine , Physics
    Notes: Abstract Calcium-binding and biochemical studies have been applied to characterize the state of the carboxylate and protein-bound phosphate groups in the EDTA-demineralized matrices of rat bone and dentine. The organic phosphate and carboxylate content of demineralized bone is virtually identical to that of purified steer skin collagen whereas demineralized dentine has a significantly higher phosphate and carboxylate content, presumably due to the presence of an acidic non-collagenous phosphoprotein. Two classes of calcium-binding sites can be detected in demineralized bone, demineralized dentine, and purified, reconstituted collagen. The number of strong calcium-binding sites correlates with the number of protein-bound phosphate groups. Depending on the preparative procedure, seven to nine such sites (per collagen molecule) are present in dentine, and one to two in the purified reconstituted collagen and in bone. The binding constant for the dentinal sites (1.1×104 M−1), however, is 20 times greater than that for bone or reconstituted collagen fibrils from skin. We tentatively conclude that the strong calcium-binding site in bone and reconstituted collagen is of the form protein-PO 4 − Ca++ whereas in dentine it is of the form the weak binding sites in bone and dentine are of the form protein-COO-Ca++; and that approximately 160 of the 217 carboxylate groups of the collagen molecules of dentine or bone are present as electrostatic linkages of the form protein-COO−+H3N-protein.
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  • 45
    ISSN: 1432-0827
    Keywords: Calcium ; Intestine ; Growth ; Cortisol ; Hydroxyproline ; Parathyroid hormone
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    Topics: Biology , Medicine , Physics
    Notes: Summary This paper reports the effects of cortisol on intestinal management of calcium and on related changes on bone metabolism. Five groups of 12 rats each fed a standard diet (0.8% Ca) received 2, 6, 16, 32, and 128 mg/kg/day of cortisol hemisuccinate, subcutaneously. After 16 days, intestinal absorption and excretion of Ca were measured with the aid of45Ca. True Ca absorption increased as a function of dose up to 16 mg/kg/day and remained high with the larger doses. Endogenous fecal Ca excretion increased exponentially as a function of the dose from 16 mg/kg/day onwards. Therefore, a dual effect was observed: (a) an increase in true Ca absorption at low cortisol doses (which increased net Ca absorption); and (b) an increase in endogenous fecal Ca excretion at high doses (which reduced net Ca absorption). In no case was a depression of true Ca absorption observed. Growth rate and food conversion efficiency were depressed only with a cortisol dose of 128 mg/kg/day. The urinary excretion of hydroxyproline, pyrophosphate, and aminopolysaccharides decreased with low doses and increased above normal levels with the highest dose. When animals treated with 128 mg/kg/day of cortisol were fed Ca-enriched diets, net Ca absorption improved. Simultaneously, growth rate and food conversion efficiency approached normal values. In these experiments, net absorption of Ca was found to be inversely related to urinary excretion of hydroxyproline. The urinary rate of excretion of hydroxyproline is suggested as an indicator of the effect of a Ca supplement on cortisol affected connective tissue turnover.
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  • 46
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    Calcified tissue international 26 (1978), S. 181-190 
    ISSN: 1432-0827
    Keywords: Cellular calcium ; Electron microscopy ; Osteoblasts ; Chondrocytes ; Mineralization
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    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium distribution in cartilage and bone cells during beginning ossification of fetal mouse long bones was studied after fixation with 2% K-pyroantimonate in 1% osmium. In the developing periosteum, the future osteoblasts showed a sparse cation-antimonate precipitate over the cytoplasm. In young osteoblasts the precipitate was accumulated on the mitochondrial membranes and the plasmalemma. Both organelles were sharply outlined by precipitate in the mature osteoblasts at the onset of mineralization. X-Ray microprobe analysis of these organelles demonstrated the presence of both Sb and Ca. In the extracellular compartment, a collagen-associated precipitate with 50 to 60 nm periodicity appeared during osteoblastic differentiation. During the initial phase of matrix mineralization, a random gross precipitate appeared in the matrix and seemed to be accumulated by osmiophilic matrix vesicles while the collagen fibrils lost their precipitate. Subsequently, during the confluent phase of matrix mineralization, the precipitate rapidly disappeared from the cells, leaving them devoid of precipitate once they were surrounded by mineralized matrix. Similar changes were found in the chondrocytes of the growth plate, but cartilage collagen, unlike osteoid collagen, did not bind precipitate. The results indicate that both osteoblasts and calcifying cartilage cells bind calcium prior to matrix mineralization. Bone collagen has strong pyroantimonate binding capacity, but it is not directly involved with initial stages of matrix mineralization, which starts in close association with matrix vesicles.
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  • 47
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    Calcified tissue international 23 (1977), S. 215-223 
    ISSN: 1432-0827
    Keywords: Amorphous mineral ; Bone ; Electron microscopy ; Ultracryotomy ; Ultramicro-incineration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The fine structure of the extracellular phase of avian medullary bone and embryonic chick femur was examined in thin sections prepared by ultracryotomy and ultramicroincineration. Since contact with solutions was completely avoided, little or no loss or dislocation of mineral constituents could occur. Amorphous bone mineral (ABM) was present in two forms: as 15–30 nm spheres and as a structure-free haze. Removal of all organic material by low temperature ashing left the ABM intact. Crystals were usually associated with the ABM. In newly ossifying regions clusters or nodules of randomly oriented crystals and ABM appeared to coalesce when they reached approximately 1 μm in diameter. In highly calcified regions crystals appeared to be oriented along collagen fibers. ABM did not appear to be associated with collagen. Unmineralized collagen was visible in osteoid after staining with dry OsO4 vapor and it appeared to be diverted around nodules. Structures which resembled matrix vesicles were present. Selected area electron diffraction patterns indicated the presence of hydroxyapatite.
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  • 48
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    Calcified tissue international 26 (1978), S. 199-202 
    ISSN: 1432-0827
    Keywords: Fluoride ; Calcium ; Phosphate ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Fluoride 27 mg was given perorally to 14 subjects. It was found that the serum fluoride concentration increased followed by a decrease to normal levels during 24 h. Serum concentrations of calcium and phosphate decreased initially whereas those of serum immunoreactive parathyroid hormone increased. After 24 h the measured quantities were within normal limits. The results are discussed with reference to mineralization of hard tissues and to fluoride treatment of osteoporotic patients.
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  • 49
    ISSN: 1432-0827
    Keywords: Solanum malacoxylon ; Vitamin D metabolites ; Rickets ; Phosphate ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of a partially purified aqueous extract ofSolanum malacoxylon (SM) leaves and of an SM extract incubated with ruminal fluid (RF) prior to administration on intestinal phosphate and calcium absorption in rachitic rats were compared with 1α, 25-dihydroxy-vitamin D3[1α,25-(OH)2-D3] using a duodenal loop in situ method. The time course responses elicited by both extracts were qualitatively similar to that of 1α, 25-(OH)2-D3. However, a single dose of SMRF was significantly more effective in stimulating32P absorption than an equivalent dose of SM. Part of this difference can be accounted for by incomplete saturation of the phosphate transport system with the level of SM employed. Treatment with rumen potentiated the effects of SM on45Ca absorption to a lesser extent. Extraction of SMRF with nonpolar organic solvents and purification of the lipid extract by chromatography on Silica Gel G thin-layer plates and on Sephadex LH-20 columns yield two fractions which promote intestinal32P absorption. The bioactive fraction eluting first from the Sephadex LH-20 column migrates similarly as 1α,25-(OH)2-D3. The greater effectiveness of SMRF extracts on intestinal phosphate and calcium absorption may be tentatively attributed to the release of 1α,25-(OH)2-D3 from the corresponding glycoside, shown previously to be present in SM, and to steroid modification during incubation with rumen.
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  • 50
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    Calcified tissue international 28 (1979), S. 17-22 
    ISSN: 1432-0827
    Keywords: Anticonvulsant ; Ketogenic diet ; Calcium ; Vitamin D ; Bone
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    Topics: Biology , Medicine , Physics
    Notes: Summary Vitamin D and mineral metabolism status was examined in five children maintained chronically on combined ketogenic diet-anticonvulsant drug therapy (KG), and the results compared to those obtained in 18 patients treated with anticonvulsant drugs alone (AD) and 15 normal controls. KG patients exhibited biochemical findings of vitamin D deficiency osteomalacia: decreased serum 25-hydroxyvitamin D (25OHD) and calcium concentrations, elevated serum alkaline phosphatase and parathyroid hormone concentrations, decreased urinary calcium and increased urinary hydroxyproline excretion, and decreased bone mass. Although the KG and AD groups demonstrated similar reductions in serum 25OHD concentration, the KG patients exhibited a significantly greater reduction in bone mass. In response to vitamin D supplementation (5000 IU/day), mean bone mass in the KG group increased by 8.1±0.9% (P〈0.001) over a 12-month period. These results suggest that ketogenic diet and anticonvulsant drug therapy have additive deleterious effects on bone mass and that these effects are partially reversible by vitamin D treatment.
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  • 51
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    Calcified tissue international 27 (1979), S. 171-176 
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Precipitation ; Double diffusion ; Collagen
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    Topics: Biology , Medicine , Physics
    Notes: Summary One-dimensional double diffusion was applied to determine critical concentrations at which the precipitation of calcium phosphates occurs in reconstituted connective tissue collagen and agar gels at 37°C and in gelatin gels at 25°C. Experiments were performed in the presence of unbuffered 0.15 mol dm−3 NaCl, or 0.15 mol dm−3 NaCl-veronal adjusted to pH 7.4. It was found that critical concentrations of precipitation of both precipitating components, CaCl2 and phosphate buffer (pH 7.4), were equimolar and independent of the ratios of initial concentrations of the components. Critical concentrations of precipitation were not affected by the concentrations and kinds of gels used. The first-formed precipitates showed amorphous structure by X-ray diffraction analyses. Infrared (IR) spectra of the precipitates indicated CaHPO4 · H2O to be their predominant species. The molar Ca/P ratio obtained by chemical analyses was 1.08. This precipitate transformed in time into octacalcium phosphate. In all experiments, two very thin membranes of precipitate were formed in the gel column at the onset of precipitation simultaneously on both sides of the actual disc of precipitate. IR spectra and chemical analyses showed that both membranes were identical to the actual precipitation discs.
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  • 52
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    Calcified tissue international 25 (1978), S. 227-232 
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Bone ; Calcium ; Chick embryo ; Organ culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The purpose of this study was to measure in an in vitro system the movement of Ca and phosphate (Pi) out of bone when treated with parathyroid hormone (PTH). Tibiae from 13-day chick embryos were incubated for up to 8 h in a defined medium containing 1.8 mM Ca. Medium samples were collected every 2 h and were analyzed for Ca, Pi and lactate. Net effluxes from the bones were calculated. When bones were incubated with PTH in the medium (1 U/ml), net Ca efflux was increased 44, 60 and 100% at 4, 6 and 8 h, respectively. At no time was net Pi efflux affected by the hormone. The well known PTH-stimulated lactate production was not seen until 8 h. Lower doses of PTH (0.1 and 0.3 U/ml) were also effective. Comparing PTH (1 U/ml) responsiveness at higher (2.2 mM) and lower (0.9 mM) medium Ca concentrations, showed that with 2.2 mM Ca no increased Ca efflux was seen, while with 0.9 mM Ca significant elevation in medium Ca occurred 2 h sooner than in the experiments using 1.8 mM Ca. In another experiment, varying the medium Pi level from 1 to 2 mM had no effect on the Ca response to PTH. In neither experiment was Pi release affected by PTH. The results of this study have led to the following conclusions: (1) PTH acts on bone to cause an early dose related increase in net Ca efflux; (2) the effect is specific for Ca, since it is not accompanied by an increased Pi efflux, and may be saturated by raising the medium Ca level; and (3) PTH-stimulated Ca efflux in this system is not correlated with, and is probably not a result of increased lactate production.
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  • 53
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    Calcified tissue international 30 (1980), S. 43-50 
    ISSN: 1432-0827
    Keywords: Osteogenesis ; In vitro ; Electron microscopy ; Mineralization
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    Notes: Summary Chick limb mesenchymal cells differentiate into muscle, cartilage, fibrous, and bone tissue. Previous reports show that when stage 24 limb mesenchymal cells are cultured in vitro, chondrocytes, myocytes, fibrocytes, and osteoblasts can be identified on the basis of morphological and biochemical parameters. The study reported here demonstrates that phenotypic expression in culture seems to be dependent on the initial plating density, Scanning electron microscopic observations indicate that when stage 24 limb mesenchymal cells are initially seeded at high densities (5 × 106 cells per 35 mm culture dish), mounds of cells appear in culture. These mounds represent cartilage nodules composed of a fine fibrous matrix and chondrocytes, surrounded by a loose fibrous connective tissue matrix. Cultures initially plated at intermediate densities (2.0–2.5 × 106 cells/35 mm culture dish) produce a flattened layer of fibrocytes overlying a matrix of collagen fibers and calcium phosphate deposits as determined by electron-microprobe analysis; these observations are indicative of osteoblast expression. Cells seeded at this intermediate density appear larger and possess greater surface area than cells seeded at high density. It is suggested that conditions that permit such increased cell surface area coupled with a relative compaction due to cell crowding may provide conditions permissive for osteogenesis. Based on morphological criteria, it appears that chick limb mesenchymal cell osteogenesis in vitro is not associated with chondrogenesis but represents a separate route of phenotypic expression.
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  • 54
    ISSN: 1432-0827
    Keywords: Rat ; Calvarium ; Electron microscopy ; Preosteoclasts ; Osteoclasts
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    Notes: Summary This is a study of the fine structure of cells of the 20-day fetal rat calvarium. Special attention is given to identifying and characterizing preosteoclasts. These cells are relatively common and located largely, but not exclusively, at the endocranial bone surface. The preosteoclasts are characterized by abundant mitochondria, an incomplete perinuclear Golgi apparatus, and variable-shaped dense granules. The dense granules are unique in appearance in that they contain an internal dense matrix surrounded by a clear halo. Most granules are circular in shape but some are elongate or tubular in form. Granules with identical appearance are observed in osteoclasts. The preosteoclasts are mononucleate, or occasionally binucleate. It is suggested that because preosteoclasts are morphologically distinctive and relatively abundant, it should be feasible to separate these cells from a heterogeneous cell isolate.
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  • 55
    ISSN: 1432-0827
    Keywords: Decalcification ; Electron microscopy ; Bone matrix ; Bone glycoproteins
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    Notes: Summary A solution of triethylammonium EDTA in 80% ethanol was evaluated as a demineralizing reagent for bone in comparison with aqueous solutions of EDTA. Biochemical analysis and acrylamide gel electrophoresis of extracts of finely powdered bovine bone showed that most of the macromolecular components of the organic matrix extractable in aqueous EDTA were retained when the triethylammonium EDTA reagent was used. Ultrastructural examination of chick tibias decalcified with the reagents showed a better preservation of cellular morphology, especially the membranous components, and more uniformly distributed ground substance, though slightly less in quantity, when the aqueous reagent was used. Use of the two reagents appears to be complementary, the alkylammonium reagent being more appropriate for use in studies of the organic matrix of bone, including immunohistochemical studies of bone glycoproteins. The aqueous reagent is more appropriate for use in studies of cellular ultrastructure.
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  • 56
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    Calcified tissue international 32 (1980), S. 229-236 
    ISSN: 1432-0827
    Keywords: Bone ; Ion influxes ; Calcium ; Phosphate ; Exchange
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    Notes: Summary Quantitative measurements were made of the ion fluxes of calcium and phosphate into and from calvaria (mouse or rat) when clamped in specially designed micro-Ussing chambers. The effects of varying concentrations of calcium were examined on the influx and efflux of calcium and of its counterion, phosphate. A comparable series of experiments was performed with varying phosphate concentrations. Both ions, as their concentrations increased, depressed their own influx, increased their own efflux, and significantly increased the equilibrium concentration, E/K, supported by the calvaria. Similarly, both ions, as their concentrations increased, affected the influx or efflux of their counterion only slightly but did depress the counterion's equilibrium level, E/K, significantly. In spite of these changes it was shown that calvaria effectively buffered the medium at physiological concentrations of calcium and phosphate. The buffering capacity, however, was small, and the balance, E/K, was modified by small uptake or loss of either ion. The small size of the interacting mineral pool was confirmed by direct measurement of the rapidly exchanging fractions of both calcium or phosphate. They were only ∼1% of the total ions present. The significance of these findings is discussed.
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  • 57
    ISSN: 1432-0827
    Keywords: Calcium ; Vitamin D deficiency ; 1,25(OH)2D3 ; Parathyroidectomy ; Parathyroid hormone
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    Notes: Summary Studies presented here were designed to investigate further the basis for an impaired cAMP response to parathyroid hormone (PTH) in osteoblastlike calvarial bone cells isolated from vitamin D-deficient rat pups. The goal was to perturb Ca, PTH, and vitamin Din vivo in order to see which factors might be responsible for the impairedin vitro bone cell cAMP response. Pups either were parathyroidectomized (PTX) 3–5 days, implanted with osmotic minipumps delivering high doses of PTH, given repeated, high doses of 1,25(OH)2D3, or were D-deficient (-D, i.e., born and suckled by D-deficient mothers). Osteoblastlike bone cells, isolated by sequential enzyme digestion and centrifugation, were exposed to PTH for 5 min in the presence of a phosphodiesterase inhibitor. In bone cells isolated from -D rat pups, both basal and PTH-induced cAMP accumulation were significantly lower than in +D bone cells. Earlier, we had shown that two daily injections of -D pups with 50 ng 1,25(OH)2D3 restores this reduced bone cAMP response of -D pups toward normal. In the present study, neither basal nor PTH-induced bone cell cAMP accumulation was affected by subjecting D-replete pups to PTX, PTH infusion, or repeated high doses of 1,25(OH)2D3 despite the fact that each treatment markedly changed serum Ca or serum immunoreactive PTH. The results indicate that the impaired bone cell cAMP response seen in -D pups is not a direct result of chronic hypocalcemia and that the “heterologous desensitization” seenin vitro with added 1,25(OH)2D3 could not be duplicated byin vivo treatment of +D pups with supraphysiologic doses of 1,25(OH)2D3. Finally the lack of alteration in the bone cell cAMP response to PTHin vitro after chronic PTH infusionin vivo fails to support the notion that the impaired response in -D bone cells can be explained entirely by “homologous desensitization” induced by high circulating levels of PTH in the hypocalcemic, -D rat pup.
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  • 58
    ISSN: 1432-0827
    Keywords: Calcitonin ; Parathyroid hormone ; Calcium ; Newborn ; Fracture
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    Notes: Summary Determinations of serum calcium (Ca), phosphorus (P), calcitonin (CT), and parathyroid hormone (PTH) were carried out in 36 full-term newborn infants with fracture of the clavicle (CF) and in 46 normal neonates (N). At the 6th hour of life the CF neonates demonstrated lower serum Ca and higher serum CT in comparison with normal infants. In the hours following, no significant differences between the two groups for the Ca levels were found, whereas serum CT remained significantly higher in the CF newborns at the 24th, 48th, and 72nd hour of life. Significant differences between normal and CF infants in the PTH serum levels were detected only at the 48th hour, when PTH was lower in the CF newborns. The results of this investigation indicate that the fracture of the clavicle is a significant and peculiar factor in stimulating CT secretion. Serum Ca level appeared to be controlled by CT rather than auto-regulating the secretion of the hormone.
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  • 59
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    Calcified tissue international 33 (1981), S. 365-368 
    ISSN: 1432-0827
    Keywords: Absorptiometry ; Osteoporosis ; Spinal bone ; Bone mineral content ; Neutron activation ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Dual-photon absorptiometry using153Gd (44 and 100 keV) was used to measure the bone mineral content (BMC) of the trunk and of the total body (TBBM) in 7 volunteers with no overt bone disease. These values were compared to those obtained with partial-body neutron activation of calcium (trunk Ca). The trunk Ca seemed to represent best a 60 × 30 cm area; the correlation coefficient with the corresponding BMC in that area was 0.97 (SEE ⋍ 7%). Trunk Ca was also highly correlated with TBBM (r=0.96; SEE=8%) and with radius BMC (r=0.92; SEE=11%), but the correlations with the BMC of smaller subareas of the trunk were lower (r⋍0.9; SEE ∼ 12%). The BMC of the lumbar spine was only moderately correlated with trunk Ca, radius BMC and TBBM (r ∼ 0.82; SEE ∼ 18%), and only slightly more associated with trunk BMC (r ∼ 0.88; SEE ∼ 14%). The BMC of the combined lumbar-thoracic spine showed higher correlations with trunk Ca, radius BMC and TBBM (r ∼ 0.87; SEE ∼ 13%), and trunk BMC (r=0.93; SEE ∼ 10%). An accurate and sensitive measure of spinal status requires a direct measurement of that area.
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  • 60
    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Strontium ; Apposition ; Tracer analysis
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    Topics: Biology , Medicine , Physics
    Notes: Abstract 1. Evidence has accumulated that the rate of acceretion (A) of calcium to bone is the sum of two fluxes; apposition involving the laying down of new bone and augmentation which is the result of slow exchange of non-surface bone calcium with plasma calcium pools as the result of solid state diffusion. 2. A method has been devised for separating A into its two components. It requires the use of45Ca or, for clinical studies,85Sr as a calcium tracer. Studies which are initiated with a combined accretion rate-calcium balance study, are concluded with an estimate of the exponent of the power function which has been found to describe the whole body retention of tracer from the second month onward. 3. The impulse response function of the skeleton for the tracer is then calculated, making the assumption that in any uniform volume of bone, osteoclastic resorption is a first order process. Making in addition certain simplifying assumptions, which are shown to have a modest influence on the final results, a mean rate of bone resorption can be calculated using a development of the well known Stewart-Hamilton formula. The apposition rate is calculated as the sum of the resorption rate and the calcium balance. Augmentation and diminution, defined as equal and opposite exchange processes, are given by the difference between A and the apposition rate. 4. The results of our first thirteen studies in normal subjects and patients with metabolic bone disease are presented, together with analyses of some data from the literature. It is concluded that the development of an atraumatic method for measuring rates of bone formation and resorption in the whole body would be an important advance in the study of metabolic bone disease, and this work is presented so that critical comparisons may be initiated between this tracer method and independent histological methods for measuring these parameters.
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  • 61
    ISSN: 1432-0827
    Keywords: Bone cells ; Cyclic AMP ; Calcium ; Ascites fluid resorptive protein
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    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of a bone resorptive protein isolated from human cancer ascites fluid on bone cell calcium and cyclic AMP were studied with fetal rat cells. The osteoclast-activating factor increased bone cell calcium uptake at 37°C and 4°C with no direct effects on calcium efflux. Concentrations of the resorptive factor that increased in vitro bone resorption and cell calcium uptake had no effect on cyclic AMP. The effects of the protein on calcium uptake were not specific for bone cells, and large increases were also observed in isolated fetal rat skin cells. These studies suggest that increases in the permeability of the cell membrane to calcium are involved in the mechanism of action of the ascites fluid resorptive protein.
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  • 62
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    Calcified tissue international 25 (1978), S. 179-190 
    ISSN: 1432-0827
    Keywords: Decalcification ; Electron microscopy ; Calcified matrices
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    Topics: Biology , Medicine , Physics
    Notes: Summary The ultrastructure of calcifying cartilage and bone has been examined under the electron microscope after using three different methods of decalcification. The first was carried out before embedding (by soaking specimens in EDTA or formic acid), the second after embedding (by floating ultrathin sections on formic acid), and the third after embedding (by soaking embedded specimens in EDTA or formic acid), and with later re-embedding. The first procedure invariably induces drastic changes in the fine structure of the cells and calcified matrix, probably as a results of the extraction of organic material along with extraction of mineral. The second and third procedures make it possible to preserve ultrastructural details perfectly in both cells and calcified matrix. Of the two, the third procedure is preferable because of its greater simplicity. In areas that are still calcifying, these post-embedding decalcification techniques reveal the presence of crystal-associated, filamentous organic structures which are not recognizable in specimens decalcified before embedding. These structures, which could have a key role in inducing and regulating crystal formation and growth, are less evident in fully calcified areas (but not at their borders). This may partly be due to the loss of glycan components in the matrix during calcification. The most important determinant, however, seems to be the fact that during calcification the components of the matrix, including collagen fibrils, are involved in an aggregation process which reduces the amounts of free chemical groups available for reaction with the stain solution. Because post-embedding decalcification does not disturb this state of aggregation, the stainability of the matrix and the electron microscopic evidence of its components remain very low.
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  • 63
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    Calcified tissue international 24 (1977), S. 191-197 
    ISSN: 1432-0827
    Keywords: Amelogenesis imperfecta ; Hypocalcification ; Hypoplasia ; Electron microscopy
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    Topics: Biology , Medicine , Physics
    Notes: Summary An ultrastructural study of teeth with amelogenesis imperfecta revelaed various aspects of microcavities in the enamel surface, which ranged from isolated imprints of ameloblasts corresponding to the mildest lesions at the end of amelogenesis, to pits caused by the death of 20 to 30 ameloblasts at the beginning of amelogenesis. Abnormalities in the shape of the prisms can be observed. Further, crystals are distributed randomly within a prism or at the junction of 2 contiguous prisms while intercrystalline spaces are widened, indicating in various places the lack of a preferred orientation of the crystals. In amelogenesis imperfecta, two different crystalline periods are found: 1 of about 250 Å, the other of about 500 Å and over. The fact that amorphous areas are found among the crystals of enamel may be related to different stages of crystallization. However, it was not possible to find any lattice defect.
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  • 64
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    Calcified tissue international 24 (1977), S. 239-242 
    ISSN: 1432-0827
    Keywords: Cementum ; Lysis ; Electron microscopy
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    Notes: Summary Examination of microradiographs from the deciduous teeth of pigs revealed large lacunae or radiolucent zones close to the cemento-dentinal junction. Electron microscopic studies of the ground sections showed areas or irregularly shaped zones devoid of mineral and filled with collagen fibers. In the wide unmineralized zones, spherical clusters of crystallites were noted. Several cementum lacunae bordered by a broad rim of unmineralized collagen fibers were noted and some lacunae also contained zones of a moderately electron dense material. This material did not yield a diffraction pattern, while the mineralized part of the cementum gave the diffraction pattern typical of hydroxyapatite.
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  • 65
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    Calcified tissue international 23 (1977), S. 87-94 
    ISSN: 1432-0827
    Keywords: Calcium ; Osteoporosis ; Lactation ; Chemistry
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    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.
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  • 66
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    Calcified tissue international 26 (1978), S. 39-45 
    ISSN: 1432-0827
    Keywords: Solanum malacoxylon ; Bone culture ; Resorption ; Calcium ; Osteoclasts
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    Topics: Biology , Medicine , Physics
    Notes: Summary The water-soluble active principle of the plantSolanum malacoxylon (SM) was partially purified by column chromatography, and its bone-resorbing activity was tested by using an organ culture system of 18-day fetal mouse fibulae prelabeled with45Ca. Three series of experiments were performed. In the first series, the aqueous extract of SM was submitted to Sephadex G-25 chromatography to separate the active substances. From six collected fractions only two exhibited reproducible bone-resorbing activity as indicated by an increased release of45Ca from bone rudiments. In the second series, the active fractions were combined and lyophilized to a powder which was dissolved in the culture media to obtain the concentrations of 5, 25, 50, and 100 μg/ml. The addition of this saltfree material resulted in a dose-related accentuation of45Ca release from fetal mouse bones into the medium. Histologically, the treated fibulae showed greater numbers of osteoclasts than the controls and a disappearance of bone trabeculae. In the third series, the active material was further purified on Sephadex LH-20 column. From four collected fractions, only one showed bone-resorbing activity in vitro. It is concluded that the purified active factor of SM exerts a direct effect on bone. It stimulates the mobilization of bone calcium in vitro by increasing the population of osteoclasts. The nature of the active principle remains unknown.
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  • 67
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    Calcified tissue international 26 (1978), S. 71-79 
    ISSN: 1432-0827
    Keywords: Absorption ; Calcium ; Mitochondria ; Intestinal epithelium ; Potassium-pyroantimonate
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    Topics: Biology , Medicine , Physics
    Notes: Summary Intracellular transport of calcium from the apical to the basal-lateral region of the intestinal epithelial cell was invetigated in duodenum from normal fed, fasted, and calcium-loaded rats. The process was followed with time using electron microscopy with potassium pyroantimonate to precipitate calcium. The observations made were subjected to morphometric analysis. The specificity of the method was demonstrated in the villus cell by resistance to micro-incineration and by absence of deposits following exposure to EGTA. Using this method calcium was seen in cells from calcium-fed rats at the microvillus border, in the Golgi zone, and within the internal compartments of the mitochondria. In cells from fasted rats calcium was not seen. Mitochondria were found largely at the apex of the cell and were free of detectable calcium. By 5 min, in the cells of fasted rats given a calcium load, the calcium had reached the Golgi apparatus and the inner mitochondrial compartment. After 15 min mitochondria were heavily loaded with calcium and had moved to the basal region of the cell. These observations suggest that mitochondria play an important role in absorption of calcium and appear to transport this ion from the apex to the basal region of the cell where entry into the capillaries takes place.
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  • 68
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Calcium ; Plasma phosphate ; Bone phosphate ; Plasma32P ; Specific activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Plasma changes in calcium, phosphate, and their radionuclides were studied in thyroparathyroidectomized (TPTX) rats treated with parathyroid hormone (PTH) for 8 h, this treatment starting 10 h after injection of45Ca and32P. Prior to intravenous infusion or hourly injections of PTH (10 mU/g/h), rats were maintained in one of three ways: on an extended fast (24 h); on a partial fast (10 h); or provided with 10% glucose and 1% calcium lactate overnight as a substitution for solid food. The pattern of change for plasma calcium,45Ca, and45Ca specific activity (S.A.) produced by PTH was not affected by these dietary conditions. The changes in phosphate were as follows: During the experimental (8 h) period, the rate of loss of32P from plasma in control rats was proportional to the length of the fast. This suggests that32P was released into plasma during the experimental period proportional to the ready availability of soft tissue glucose. In rats on an extended fast, PTH was phosphaturic, hypophosphatemic, and increased the rate of loss of32P from plasma without affecting32P S.A. values. In rats fasted for only 10 h, PTH produced similar effects on plasma phosphate and plasma32P values, but also caused a significant fall in plasma32P S.A. After glucose and calcium lactate treatment, PTH-induced phosphaturia was temporarily lost and the marked hypophosphatemia was replaced with a slight hyperphosphatemia. Plasma32P values also rose slightly; therefore, no effect on32P S.A. was produced. It is concluded from these studies that as the result of the phosphaturia caused by PTH, the hypophosphatemia which is produced automatically changes the phosphate gradient between various body compartments, causing phosphate entry into plasma. The authors postulate that this phosphate entering plasma is withdrawn primarily from bone fluid and bone.
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  • 69
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    Calcified tissue international 24 (1977), S. 271-274 
    ISSN: 1432-0827
    Keywords: Enamel ; Mineralization ; Calcium
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    Topics: Biology , Medicine , Physics
    Notes: Summary The potassium pyroantimonate technique was used to study the cellular distribution of calcium during the early mineralization of enamel in rat molar tooth germs at the electron microscope level. Differing patterns of calcium distribution were observed in the ameloblast seemingly associated with the appearance of Tomes' process. In the early secretory ameloblast calcium pyroantimonate deposits were observed within the Golgi apparatus, within coated vesicles, within mitochondria and associated with the inner aspect of the cell membrane. However, with the development of Tomes' process the ameloblasts no longer demonstrated these discrete deposits of calcium pyroantimonate. Instead they showed a diffuse cytoplasmic staining pattern with no preference for any particular organelle.
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  • 70
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    Calcified tissue international 25 (1978), S. 45-51 
    ISSN: 1432-0827
    Keywords: CaCO3 ; Amino acids ; Sheaths ; Ligament ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The aragonite crystals in the molluscan bivalve hinge ligament are surrounded by an organic sheath which is distinct from the remainder of the ligament matrix. Methods have been developed to isolate these sheathed crystals from the ligaments ofSpisula solidissima andMercenaria mercenaria employing a papain digestion of the matrix protein. The sheathed crystals fromSpisula have a CaCO3/protein ratio of 11.1 and those fromMercenaria a ratio of 29.6. The sheathed crystals and the empty crystal sheaths have been examined by electron microscopy for structural integrity. The sheath proteins exhibit much smaller proportions of the amino acids glycine and methionine than the hinge ligaments. These are characteristic amino acids of high concentration in the hinge ligaments of both species. The concentrations of acidic and basic amino acids are increased about two fold in the sheaths over those of the ligaments. Otherwise there is little similarity in the amino acid composition of the sheaths in the two species. However, SDS electrophoresis shows the sheaths of both to contain a major protein component with a molecular weight of about 25,000. The sheath protein from theMercenaria ligament contains about 5% carbohydrate and that ofSpisula sheaths less than 1% carbohydrate.
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  • 71
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    Calcified tissue international 27 (1979), S. 13-18 
    ISSN: 1432-0827
    Keywords: Anticonvulsants ; Calcium ; Vitamin D ; Parathyroid hormone ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Parameters of mineral metabolism were examined in 6 patients with moderately severe anticonvulsant drug-induced osteomalacia. Compared to 15 matched controls, the patients exhibited significantly reduced serum calcium, inorganic phosphate, and 25-hydroxyvitamin D concentration, elevated serum alkaline phosphatase and immunoreactive parathyroid hormone (iPTH) concentration, reduced intestinal47Ca absorption, reduced urinary calcium and increased urinary hydroxyproline excretion, and reduced forearm bone mass. Intestinal absorption of vitamin D3 was normal. Following 4 months of treatment with vitamin D3 (4000 units/day), serum 25-OHD concentration was increased to 3 times mean normal values and all parameters except serum iPTH, urinary calcium excretion, and forearm bone mass were returned to levels not significantly different from normal. Serum iPTH concentration was reduced by 39% (P〈0.05); 24-h urinary calcium excretion rose by 98% (P〈0.001), and forearm bone mass increased by 5.6% (P〈0.05). It is concluded that moderate-dose vitamin D3 supplementation is effective in normalizing parameters of mineral metabolism in this disorder, despite evidence of resistance to the biologic effects of vitamin D.
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  • 72
    ISSN: 1432-0827
    Keywords: Calcium ; PTH ; 1,25(OH)2D ; Acid ; Bone
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    Topics: Biology , Medicine , Physics
    Notes: Summary We measured mineral and acid balances, serum iPTH, urinary cAMP/creatinine, and plasma concentrations of 25OHD and 1,25(OH)2D in 7 healthy adults during control conditions and during increased fixed acid production achieved either by the administration of NH4Cl (N=3) or by increased dietary protein intake (N=4). When acid production was increased, the subjects were in positive acid balance and negative Ca balance because of increased urinary Ca excretion. Serum iPTH fell slightly but urinary cAMP and the plasma levels of vitamin D metabolites did not change. We conclude that the accelerated skeletal and urinary losses of Ca that occur when fixed acid production is increased are not contributed to nor compensated for by the parathyroid-vitamin D endocrine systems.
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  • 73
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    Calcified tissue international 29 (1979), S. 63-69 
    ISSN: 1432-0827
    Keywords: Vaterite ; Calcium ; Eggshells ; Cuckoos
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    Topics: Biology , Medicine , Physics
    Notes: Summary The crystalline spherules occurring in patches on the outer surface of the eggshells ofGuira guira and the bloom on the entire outer surface of those ofCrotophagi ani were shown by X-ray diffraction analysis to be vaterite.
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  • 74
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    Calcified tissue international 29 (1979), S. 101-105 
    ISSN: 1432-0827
    Keywords: Osteon ; X-ray diffraction ; Pole figures ; Electron microscopy ; Calcification
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    Topics: Biology , Medicine , Physics
    Notes: Summary The X-ray diffraction method based on pole figures has been applied to single osteon samples in order to obtain information about the texture of the inorganic bone fraction and the way it changes during calcification. The osteon samples were cylindrically shaped, with axes corresponding to those of the haversian canals. Selection was carried out according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteons were selected: longitudinal, alternate, and transversal. The results indicate that in all three types of osteons, the long axis of the sample is apparently the only direction of orientation because the transversally oriented crystallites give an isotropic diffuse scattering as would be expected if all the inorganic particles were irregularly oriented around the osteon axis. The number of longitudinally oriented crystallites increases progressively from transversally oriented osteons to alternately and longitudinally oriented ones. The crystallite orientation in an axial direction increases in fully calcified osteons. This last result is in agreement with the electron microscopic finding that the long needle-shaped crystallites covering much more than a major collagen period and measuring 40–45 Å in width increase in number as calcification proceeds.
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    Calcified tissue international 29 (1979), S. 155-161 
    ISSN: 1432-0827
    Keywords: Periosteal cells ; Calcium ; PTH ; CT ; Metabolic inhibitors
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    Topics: Biology , Medicine , Physics
    Notes: Summary Calcium transport was studied in cells isolated from cultured periostea of 18-day-old chick embryos. Net calcium uptake was stimulated by iodoacetate (IAA) and inhibited by dinitrophenol (DNP). Calcium efflux from the intracellular compartment was inhibited by IAA. Changes in the extra-or intracellular sodium concentration had only minor effects on calcium transport. This indicates that calcium efflux from periosteal cells is probably directly dependent on ATP hydrolysis, whereas calcium-sodium exchange is of less importance. The cation ionophore A23187 stimulated calcium uptake during short incubations but was inhibitory in long incubations. The possible involvement of the mitochondria in this effect is discussed. Parathyroid hormone (PTH) and calcitonin (CT) stimulated the net uptake of calcium in relatively low doses (both 0.01 U/ml or higher). The effects of the hormones on net calcium uptake were not additive. Calcium efflux was not changed in the presence of PTH or CT.
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  • 76
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    Keywords: Hydroxyapatite ; Dissolution ; Pyrophosphate, Diphosphonates ; Calcium ; Phosphate
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    Notes: Summary Pyrophosphate and diphosphonate ions have been said to diminish the dissolution of hydroxyapatite crystals, because they lower the equilibrium concentrations of calcium and phosphate ions in the bulk solution around hydroxyapatite crystals in a closed system. However, in a closed system these effects are not necessarily due to an effect on dissolution alone. In this paper we have used a continuous flow system to study the effects of pyrophosphate and two diphosphonates, ethane-1-hydroxy-1,1-diphosphonate and dichloromethane diphosphonate, on the dissolution of hydroxyapatite. All three compounds decreased markedly the rate of dissolution of hydroxyapatite as well as the exchangeable pools of calcium and phosphate ions around the cystals.
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    Calcified tissue international 31 (1980), S. 231-238 
    ISSN: 1432-0827
    Keywords: Magnesium ; Bone ; Calcium ; Parathyroid gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Calcium homeostasis and bone pathology were studied in weanling rats fed a low (70 ppm) magnesium diet for 2–21 days. The rats developed significant, progressive hypercalcemia after 6 days on the diet. The increase in blood calcium was accompanied by progressive hypoactivity of the parathyroid gland (PTG), as determined by histologic and morphometric analyses. Thus hyperactivity of the PTG could not have been responsible for the hypercalcemia observed. Histologic examination of femora and humeri from magnesium-deficient rats showed progressive subperiosteal hyperplasia, consisting of undifferentiated osteoprogenitor cells and fibrous tissue, after 7 days of deficiency. The presence of unmineralized osteoid tissue in the metaphyses indicated that mineralization was not proceeding normally. The alterations in differentiation of osteoprogenitor cells, together with the failure of mineralization, resulted in significantly lower rates of bone formation (as measured by fluorochrome labeling) in the magnesium-deficient rats. Basophilic cementing lines and inactive osteocytes in the cortices of bones from magnesium-deficient rats indicated that bone resorption was also severely reduced in magnesium deficiency. We postulate that bone magnesium depletion (66% by day 21) has a direct negative effect on osteoblastic and osteocytic activity, and may explain, in part, the decreased responsiveness of bone to parathyroid hormone (PTH) that has been observed in magnesium-deficient animals.
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    Calcified tissue international 32 (1980), S. 45-53 
    ISSN: 1432-0827
    Keywords: Dentin ; Periodicity ; Allometry ; Calcium ; Sulfur
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    Notes: Summary We have described differences in the aspects of biological rhythms for calcium and sulfur deposition on the labial and lingual sides of the growing rabbit incisor, where growth occurs along a spiral axis. The calcium oscillations appear to be smoother on the labial side than on the lingual side. The lingual side is characterized by high-frequency rhythms with high amplitudes which possess the greatest percent of the power (Fourier analysis). These observations also reflect a difference in behavior of the mean Ca concentration across the labial and lingual sides. Sulfur rhythms on the labial side have higher amplitudes than those on the lingual side, but systematic differences in distribution of power between high and low frequencies is not as pronounced as in the case of Ca. The differences in Ca rhythms reflect differences in the growth rates of incisors on either side of the spiral axis. The labial side grows slightly faster than the lingual side, and its odontoblasts secrete Ca along the spiral axis and toward the pulp cavity at the same time. Thus the resultant direction of growth is more nearly opposite the extension of the occlusal end on the labial side, and Ca is consequently deposited over a wider area relative to that on the lingual surfaces. On the lingual side, Ca is deposited within a more limited area, and growth must therefore be continuous at high frequencies. The distribution of Ca on both sides of the tooth reflects these differences in growth rate and periodicity in two ways. First, given a unit area of tooth, the calcium concentration on the labial side is less than that of the lingual side. Second, whereas the calcium concentration on the labial side declines rapidly from the enamel-dentin junction to the pulp cavity, it is uniformly high across the lingual side because its growth is more continuous at high frequencies.
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  • 79
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    Keywords: 1α-Hydroxy vitamin D3 ; 1,25-Dihydroxyvitamin D3 ; Calcium ; Transport ; Intestine
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    Topics: Biology , Medicine , Physics
    Notes: Summary The timed sequence of events following the oral administration of 1α-hydroxy vitamin D3 (1αOHD3) to rachitic chicks was compared to that following a comparable dose of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). RNA polymerase activity was maximally increased 20% by 1αOHD3 within 1 to 2 h and returned to control values after 8 h. Alkaline phosphatase activity was stimulated by 4 h and was maximal (3- to 5-fold increase) at 24 h. Calcium binding protein (CaBP) was detected initially within epithelial cells at the proximal end of the villus (just above the crypt) 6 to 8 h after 1αOHD3 administration, in epithelial cells lining the proximal half of the villus by 24 h, and in epithelial cells along nearly the entire villus by 48 h. At no time did goblet cells contain CaBP. Serum calcium concentrations were significantly elevated in 2 h and maximal by 12 h (an increase of 3.6 mg/dl). Calcium accumulation by the intestinal mucosa in vitro was increased by 6 to 8 h and maximal (60% increase over controls) at 24 h. Phosphate accumulation by the intestinal mucosa in vitro was increased by 6 h and maximal (105% increase over controls) between 8 and 24 h. 1,25(OH)2D3 increased CaBP and calcium accumulation by 4 h, 2 h sooner than did 1αOHD3. 1,25(OH)2D3 decreased serum calcium levels and increased serum phosphate levels at 2 h unlike 1αOHD3. No difference in the effects of these compounds on alkaline phosphatase activity, RNA polymerase activity, and phosphate accumulation could be demonstrated. These results are consistent with the possibility that 1αOHD3 may not require conversion to 1,25(OH)2D3 for all of its biological effects.
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  • 80
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    Keywords: Perifusion ; Parathyroid hormone ; In vitro ; Calcium ; Beta regulation
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    Notes: Summary An in vitro perifusion system was used to study parathyroid hormone (PTH) secretion in response to calcium (Ca) and beta-adrenergic agents. Perifused parathyroid tissue responded to changes in Ca within the physiologic range during experiments up to 5 h. There was rapid secretory stimulation after exposure to low Ca, with the maximum response being observed at 20 min. Normal bovine glands showed a Ca-independent nonsuppressible component of PTH release at concentrations of Ca above physiologic. 1-isoproterenol produced rapid stimulation of PTH release, the response being blocked by a beta antagonist. The maximum secretory response to either low Ca (0.5 mM) or 1-isoproterenol (10−5 M) was enhanced when the two stimuli were applied simultaneously. The response to isoproterenol was blocked by raising Ca to 2.5 mM. Although d,l-propranolol (10−4 M) caused mild suppression of PTH release at a Ca of 1.25 mM, it did not cause additional suppression at 2.5 mM Ca nor did it decrease the response to 0.5 mM Ca stimulation. The secretory response of the gland to low Ca was sustained at a level more than double the baseline rate. The response to isoproterenol was more transient, with a return to or toward baseline secretion within 60 min. These results suggest that beta agonists and low Ca have separate but related mechanisms for stimulating PTH release and may affect different pools of hormone. The perifusion system described is a relatively simple technique for assessing the kinetics and interactions of various stimulators of PTH secretion.
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  • 81
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    Calcified tissue international 32 (1980), S. 29-44 
    ISSN: 1432-0827
    Keywords: Rabbit ; Dentin ; Calcium ; Sulfur ; Periodicity ; Circadian ; Ultradian
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    Topics: Biology , Medicine , Physics
    Notes: Summary We have identified a variety of biological rhythms involved in the apposition and mineralization of dentin in the rabbit incisor. Animals were injected during the day or night with lead acetate at 2-week intervals—to provide biological time markers in forming dentin—and transverse undecalcified sections of the lower incisors were prepared for electron microprobe analysis. The positions of the lead markers were identified, and the continuous distribution of calcium and sulfur was measured at 1 µm intervals between the markers. In thin sections stained with hematoxylin after decalcification, the widths of a series of structural increments (bands) were measured with an ocular micrometer. Fourier analysis of the data revealed spectra of structural and compositional rhythms with a range of periodicities which extended from a matter of hours [ultradian (〈24 h)] to days [infradian (〉24 h) and circadian (approximately 24 h)]. The structural and compositional rhythms appeared to be independent to the extent that they did not necessarily have the same periods, or amplitudes. Nor were there simple phase relationships between all of the rhythms. At some times, Ca and S fluctuations are inversely proportional (180° out of phase), but in other cases they are directly proportional or out of phase by varying degrees other than 180°. The analyses thus suggest that calcium and sulfur deposition (representing mineral and glycosaminoglycan deposition, respectively) are not simply inversely proportional, and that the hematoxylin-stained structural increments did not solely reflect differences in the distribution of the mineral components in dentin.
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  • 82
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    Calcified tissue international 34 (1982), S. 253-257 
    ISSN: 1432-0827
    Keywords: Prednisolone ; Calcium ; Bone ; Corticoid osteopenia ; Vitamin D metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Adult male rats were fed a diet containing 0.15% calcium, 0.3% phosphorus, and either 100, 50, or 20 mg of prednisolone per kg of diet. All these levels of prednisolone led to osteopenia, decreased intestinal absorption of calcium, slightly lower serum calcium and phosphorus, and a decreased level of serum 1,25-dihydroxyvitamin D3. Exogenous parenteral 1,25-dihydroxyvitamin D3 corrected steroid-induced changes in serum calcium and phosphorus, but could not completely correct the low intestinal calcium transport; nor did it prevent the development of osteopenia. The prednisolone-induced osteopenia seems at least in part to be caused by impaired intestinal calcium transport. The impaired calcium transport may be the result of low levels of 1,25-dihydroxyvitamin D3 and a direct effect of presnisolone on the intestine.
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  • 83
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    Calcified tissue international 36 (1984), S. 596-603 
    ISSN: 1432-0827
    Keywords: Calcium ; Ameloblasts ; X-ray microanalysis ; Transport ; Frozen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Energy dispersive X-ray microanalysis was applied to freeze-dried blocks of enamel organ tissue to determine levels of calcium in various celular regions. The tissue blocks were dissected free from adjacent forming enamel following injection of cobalt or fluoride ions, both of which temporarily inhibit enamel mineralization. In all control and experimental specimens there was an increasing gradient of calcium from the stratum intermedium cells to the distal ends of the ameloblasts. Calcium levels were significantly reduced near the distal ends of the ameloblasts following cobalt or fluoride injection as compared with controls. It is suggested that evidence of an intercellular buildup of calcium near the distal ends of the ameloblast supports a controlling function of these cells. The changes in calcium levels are correlated with alterations in mineralization known to occur in the adjacent enamel of the model systems employed.
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  • 84
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    Calcified tissue international 33 (1981), S. 477-484 
    ISSN: 1432-0827
    Keywords: 1,25-(OH)2-D ; Calcium ; Phosphorus ; Sex ; Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Dietary phosphate deprivation in women, but not men, is accompanied by a fall in plasma PO4 and a rise in plasma 1,25-(OH)2-vitamin D concentrations. In contrast, young male rats exhibit a fall in plasma PO4 and a rise in plasma 1,25-(OH)2-D concentrations in response to PO4 deprivation. To evaluate whether age and sex influence basal plasma 1,25-(OH)2-D levels and their regulation by PO4 deprivation, plasma 1,25-(OH)2-D, PO4, and Ca levels were measured in male and female rats ranging in age from 6 weeks to 6 months while they were eating normal or low PO4 diets for 1 to 16 days. Similar observations were also made in 6-week-old castrated male and female rats, males replaced with testosterone, and females replaced with estradiol. Basal plasma 1,25-(OH)2-D levels were higher in 6-week-old males (228±76 pmol/l) than in 6-week-old females (148±62 pmol/l;P〈0.01) and declined by age 11 weeks to stable levels averaging about 100 pmol/l without sex difference. Dietary PO4 deprivation resulted in a three-to fourfold increase in plasma 1,25-(OH)2-D concentrations regardless of age and sex, accompanied by a correlated rise in serum Ca concentrations. Castration of 6-week-old males and females eliminated the sex difference in basal plasma 1,25-(OH)2-D levels and appeared to enhance the elevation of plasma 1,25-(OH)2-D concentrations in response to PO4 deprivation in females. Although gonadal hormones may modify basal plasma 1,25-(OH)2-D levels, they are not required for the augmentation of plasma 1,25-(OH)2-D levels in response to PO4 deprivation.
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  • 85
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    Calcified tissue international 33 (1981), S. 575-581 
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Vitamin D ; Bone mineral ; Estrogen ; Aging ; Thiazide ; Fluoride ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Bone mineral content (BMC) was measured by125I photon absorptiometry every 3 months in 264 normal females (45–54 years) over a 2-year period together with serum samples for calcium, phosphate, magnesium, creatinine, alkaline phosphatases, potassium, and protein. A 48-h urinary calcium and creatinine measurement was obtained. The subjects were divided into 7 treatment groups and 3 placebo groups. Five of the treatments (thiazide, vitamin D3, fluoride + vitamin D3, fluoride, and 1αD3) were ineffective at the doses used; the annual loss of compact bone was 1.5–2.2% (-X=1.8%), similar to the loss seen with placebos. Estrogen and estrogen + thiazide, in contrast, produced a 1.34% annual increase of BMC. The subjects were divided into groups with low, medium, and high initial BMC. Also, individual regressions for bone change were calculated and the subjects were divided into groups of responders, maintainers, and losers (annual change of 〉0%, 0 to −1%, and 〉−1%, respectively). The initial BMC status did not consistently affect bone or biochemical responses to the therapeutic agents. Estrogen was effective even in subjects with high BMC, whereas the other agents did not inhibit bone loss even in subjects with low initial BMC. Virtually all subjects responded to estrogen positively; in contrast we could not identify a subset of “responders” with any of the other treatments. Time since menopause appeared to influence the bone changes, although it was not a significant effect given the sample size. Bone loss in groups not treated with estrogens was 2%/year at 20 months after menopause with a decline to 1.3%/year at 45 months post-menopause. There was no apparent decline in the bone response to estrogen during the first 4 years after menopause, and in fact bone response tended to increase with time.
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    Calcified tissue international 33 (1981), S. 485-488 
    ISSN: 1432-0827
    Keywords: 1,25-(OH)2-D ; Hypophysectomy ; Calcium ; Phosphorus
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    Topics: Biology , Medicine , Physics
    Notes: Summary The mechanism by which dietary phosphate deprivation elevates plasma 1,25-(OH)2-D levels is not known. To evaluate the role of the pituitary in regulating plasma 1,25-(OH)2-D concentrations, the responses of plasma 1,25-(OH)2-D to dietary phosphate deprivation and, separately, to dietary calcium deprivation were evaluated in intact and hypophysectomized male rats. Among intact and hypophysectomized rats eating normal diets, plasma 1,25-(OH)2-D levels averaged 228±76 and 148±62 pmol/1, respectively (P〈0.01). During dietary phosphate deprivation, plasma 1,25-(OH)2-D levels rose to 1160±260 in intact rats and fell to 90±26 pmol/l in hypophysectomized rats (P〈0.001). By contrast, during dietary calcium deprivation, plasma 1,25-(OH)2-D levels rose in both intact and hypophysectomized animals to 856±107 and 742±279 pmol/l, respectively (NS). In response to dietary phosphate deprivation, serum calcium concentrations rose as 1,25-(OH)2-D concentrations rose in intact rats but remained at control levels in hypophysectomized rats. These results support the hypothesis that a pituitary hormone acting either directly or indirectly on the kidney mediates the increase in plasma 1,25-(OH)2-D during dietary phosphate deprivation. The hypercalcemia that occurs in rats during dietary phosphate deprivation appears to depend on the elevation of plasma 1,25-(OH)2-D.
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  • 87
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    Calcified tissue international 33 (1981), S. 119-124 
    ISSN: 1432-0827
    Keywords: Avian eggshell ; Microstructure ; Electron microscopy ; Electron diffraction ; Calcite growth
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    Topics: Biology , Medicine , Physics
    Notes: Summary The eggshell of the domestic fowl has been studied by transmission electron microscopy and diffraction. Thin sections of shell were prepared by chemical and ion-beam thinning techniques. Each calcite column of the palisade layer consisted of crystallites of diameter 20 to 30 µm with some tendency for crystallite alignment within a single column. Evidence indicates that there was no significant preferred orientation in the palisade layer as a whole. Only in the surface layer was any preferred orientation detected, and here {1014} planes tended to lie parallel to the surface. The results are compared with previously published data, and calcite nucleation and growth are discussed.
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  • 88
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    Calcified tissue international 22 (1977), S. 183-189 
    ISSN: 1432-0827
    Keywords: Calcium ; Strontium ; Bone ; Mathematical modelling
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    Notes: Abstract 1. A method has been devised for comparing the impulse response functions of the skeleton for two or more boneseeking tracers, and for estimating the contribution made by measurement errors to the differences between any pair of impulse response functions. 2. Comparisons were made between the calculated impulse response functions for47Ca and85Sr obtained in simultaneous double tracer studies in sixteen subjects. Collectively the differences between the47Ca and85Sr functions could be accounted for entirely by measurement errors. 3. Because the calculation of an impulse response function requires fewera priori assumptions than other forms of mathematical analysis, and automatically corrects for differences induced by recycling of tracer and non-identical rates of excretory plasma clearance of tracer, it is concluded that differences shown in previous in vivo studies between the fluxes of*Ca and*Sr into bone can be fully accounted for by undetermined oversimplifications in the various mathematical models used to analyse the results of those studies.85Sr is therefore an adequate tracer for bone calcium in most in vivo studies.
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  • 89
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    Calcified tissue international 24 (1977), S. 275-278 
    ISSN: 1432-0827
    Keywords: Calcium ; Thyroid ; Calcium ; Thyroïde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les auteurs utilisent une solution de Glyoxal bis 2-hydroxyanil à basse température pour localiser le calcium dans la thyroïde. Grâce à cette technique qui limite les mouvements ioniques, ils observent que le calcium situé principalement dans la colloïde est résorbé en même temps qu'elle lors d'une stimulation par le froid.
    Notes: Summary With a Glyoxal bis 2-hydroxyanil alcoholic solution at −25°C, the calcium was localized in frozen thyroid slices. The limited ionic movement permits seeing that the calcium situated principally in the colloid is resorbed at the same time by a low temperature stress.
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  • 90
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    Calcified tissue international 25 (1978), S. 133-143 
    ISSN: 1432-0827
    Keywords: Osteon ; X-Ray diffraction ; Electron microscopy ; Calcification
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    Topics: Biology , Medicine , Physics
    Notes: Summary To obtain information on the changes in the inorganic bone fraction during calcification, low- and wide-angle X-ray diffraction techniques and electron microscopy have been applied to single osteon samples. The samples were cylindrically shaped and their axes corresponded to the axes of the Haversian canals. The selection was made according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteon were selected, that is, longitudinally structured osteons, transversely structured osteons, and alternately structured osteons. The results indicate that in osteonic lamellar bone there are two types of inorganic particles: (1) granules arranged in linear or needle-shaped entities with maximum width 40–45 Å, which are regularly distributed at the level of the main band of the collagen fibrils where their maximum length reaches the length of the main band itself; that is, about 400 Å; and (2) very long crystallites, with a diameter of 40–45 Å, which grow with their crystallographicc-axis parallel to the collagen fibrils and cover much more than a major collagen period.
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  • 91
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    Calcified tissue international 30 (1980), S. 27-34 
    ISSN: 1432-0827
    Keywords: Ultrastructure ; Calcium ; Cartilage ; Vesicles
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    Topics: Biology , Medicine , Physics
    Notes: Summary The potassium pyroantimonate technique was utilized for the selective subcellular localization of calcium in the mandibular condylar cartilage of 1-day-old rats. Electron dense calcium pyroantimonate precipitates were localized principally in mitochondria and at the cell membrane of the chondrocytes. In addition, small intracellular vesicles 0.1–0.2µm in diameter were observed in proximity to the cell membrane of chondrocytes of the mid-hypertrophic zone. The results suggest that these vesicles were being extruded from the cell into the extracellular matrix. Energy-dispersive analysis by X-rays confirmed that calcium is the principal cation of the electron-dense precipitates.
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    Calcified tissue international 34 (1982), S. 43-48 
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Phosphatidylserine ; Transport ; Mineralization
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    Notes: Summary Experiments were performed to study the effect of inorganic phosphate (Pi) on phosphatidylserine-mediated Ca2+ transport utilizing two- and three-compartment lipid-aqueous phase model systems. When the three-compartment model was used, the rate of Ca2+ transport from an aqueous donor compartment to an aqueous receiver compartment, separated by a nonaqueous phospholipid phase, was determined. This experiment showed that the rate of Ca2+ transport was proportional to the phosphatidylserine concentration and the pH. Pi modulated the rate of Ca2+ transport; even when the Pi concentration of the donor aqueous phase was low, there was a marked enhancement of transport. To determine whether the Pi-mediated rise in the Ca2+ transport rate was due to an increase in the uptake of Ca2+ into the lipid phase, or to an increase in the ability of the lipid phase to release Ca2+, a two-compartment model was used. It was found that the ability of the phosphatidylserine phase to take up Ca2+ increased as the Pi concentration of the aqueous donor phase was raised. With the increase in Ca2+ uptake there was a concomitant elevation in the rate of Ca2+ transport into an aqueous receiver phase. However, Pi did not stimulate Ca2+ release from the phosphatide. Thus it was concluded that Pi enhanced the interaction between Ca2+ and phosphatidylserine, possibly by forming a Ca-phospholipid-Pi complex. Once this interaction had taken place, Ca2+ release into the aqueous receiver compartment was independent of the Pi concentration.
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  • 93
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    Calcified tissue international 36 (1984), S. 77-82 
    ISSN: 1432-0827
    Keywords: Osteogenesis ; Diffusion chambers ; Alkaline phosphatase ; Calcium ; Phosphorus
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    Notes: Summary The alkaline phosphatase activity and the calcium and phosphorus content of osteogenic tissue formedin vivo following the implantation of diffusion chambers loaded with rabbit bone marrow cells is reported. (In this study the term osteogenic includes osteoblastic and chondroblastic.) Chambers examined 14–70 days after implantation revealed progressive accumulation of mineral. Alkaline phosphatase activity increased until day 30 and declined thereafter. The osteogenic potential of the marrow cells decreased with increasing weight (age) of the cell donor rabbit when measured either as the percentage of chambers containing osteogenic tissue or as the amount of calcium, phosphorus, or alkaline phosphatase activity within the chambers. The results confirm that measurements of these parameters in tissue formed by cells incubated in diffusion chambersin vivo may be used as a method for assay of osteogenesis.
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  • 94
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    Calcified tissue international 36 (1984), S. 269-273 
    ISSN: 1432-0827
    Keywords: Bone loss (osteopenia) ; Calcium ; Corticosteroids (glucocorticosteroids) ; Fluoride ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To evaluate the effect of prednisone and triple treatment (sodium fluoride, calcium, and vitamin D) on trabecular and cortical bone serial bone mineral content (BMC) measurements were made at a metaphyseal (BMCD) and diaphyseal (BMCP) site on the forearm on 31 consecutive and previously bone-healthy patients scheduled for at least 24 weeks high-dose prednisone treatment. The patients were randomized into two further treatment groups: group I (n=16) received prednisone plus triple treatment and group II (n=15) received only prednisone. The two groups were similar with regard to age, sex, prednisone dose, and initial BMC. During 24 weeks treatment, BMCD (partially representing trabecular bone) and BMCP (mainly representing cortical bone) fell significantly and similarly, demonstrating that there is no preventive effect on bone mineral loss on the triple regimen. The BMC fall after 12 weeks was significantly more pronounced for metaphyseal (partially trabecular) than for diaphyseal (cortical) bone, whereas the values did not differ significantly after 24 weeks; this indicates a greater sensitivity to the hormone treatment of trabecular bone. In the entire group, the fall in BMC correlated positively with individual prednisone dose, significant at the diaphyseal site (r=0.39,P〈0.05), but not at the metaphyseal site (r=0.31, P=0.08). It is concluded that corticosteroid-induced osteopenia is a diffuse bone disease which affects trabecular as well as cortical bone, suggesting that BMC measured on the forearm reflects changes in bone mineral at other locations.
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    Calcified tissue international 36 (1984), S. 392-400 
    ISSN: 1432-0827
    Keywords: Vitamin D ; Chick embryo ; Bone ; Calcium ; Phosphate
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    Topics: Biology , Medicine , Physics
    Notes: Summary Chick embryos were injected in the yolk sac at various ages with various doses of different vitamin D3 metabolites. Serum concentrations of total calcium and inorganic phosphate were determined 24 h after the injection and histological and electron microscopic studies of the tibiae were conducted 3–6 days after. Confirming previous results, the injection of 1,25(OH)2D3 was found to produce significant hypercalcemia and hypophosphatemia. The dose required to produce these effects decreased with age: 100 ng on the 9th day, 50 ng on the 11th, and 10 ng on the 15th. This finding is interpreted as resulting from the fact that the specialized cells in the chorionic epithelium which are considered to be involved in mineral resorption from the shell differentiate between the 11th and 13th days. Although no bone changes were observed in embryos injected before the 11th day, a rim of unmineralized trabeculae (osteoid) was observed at the periphery of the cortex of the tibial diaphysis in the embryos which had been injected after that age. Thus, in embryos injected on the 11th day with 100 ng 1,25(OH)2D3, the trabeculae formed between the 11th and 14th day remained unmineralized until the 15th or 16th day at which time they completed their mineralization. In the embryos injected on the 14th day, the alterations were more severe and could be produced with doses 10 times smaller than those required when the injections were made on the 11th day. At all ages, the doses that produced an osteoid rim also induced hypercalcemia and hypophosphatemia. The electron microscopical study of the osteoid trabeculae showed that osteoblasts and osteocytes had normal cytological characteristics and that the bone matrix did not present changes other than the reduction in mineral deposition. While the above findings do not exclude a direct action of 1,25(OH)2D3 on bone cells as the mechanism of osteoid formation, they do underline the importance of the humoral changes at least as partial determinants of this phenomenon. The activities of various vitamin D metabolites were compared using as parameter the threshold-dose required to produce a rim of unmineralized trabeculae in the tibia of 14–15 days embryos (T-D). The most active metabolite appeared to be 1,25(OH)2D3 (T-D: 10 ng); it was followed by 1,24,25(OH)3D3 (T-D: 100 ng) and 1,25,26(OH)3D3 (T-D: 100 ng). Vitamin D3 itself (T-D: 100 µg), 25(OH)D3 (T-D: 2.5µg) and 24,25(OH)2D3 (T-D: 5 µg) produced similar responses but only when administered in much larger doses.
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    Calcified tissue international 36 (1984), S. 702-710 
    ISSN: 1432-0827
    Keywords: Corticosteroids ; Cartilage ; Organ culture ; Calcium ; Matrix vesicles
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    Topics: Biology , Medicine , Physics
    Notes: Summary The present study examined the effects of various corticosteroid and noncorticosteroid hormones upon the ultrastructure of chondroprogenitor cells and chondroblasts in an organ-culture system of late fetal condylar cartilage. Corticosteroids, (triamcinolone acetonide, dexamethasone, corticosterone) at concentrations of 10−6–10−8M stimulated markedly a precocious formation of matrix vesicles by chondroblasts. This stimulation was accompanied by a significant accretion of calcium complexes intra- and extracellularly in both the chondroprogenitor cell population and chondroblastsin vitro, as well as in the newly induced matrix vesicles. Nonglucocorticoid steroids (progesterone, estradiol, testosterone, cortexolone) did not evoke similar effects. Progesterone and testosterone, however, seemed to adversely affect the ultrastructure of the cartilage cells, whereas estradiol appeared to have a favorable effect on the morphology of cultured condylar cartilage.
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    Calcified tissue international 34 (1982), S. 121-124 
    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Metabolism
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    Notes: Summary Bone Gla protein (BGP) was measured in the plasma by radioimmunoassay (RIA) during treatment of 59 patients with bone diseases including Paget's disease (N=9), primary hyperparathyroidism (N=25), chronic renal failure (N=20), and cancer involving bone (N=5). Plasma BGP was increased above normal in all patients. BGP decreased in the patients with Paget's disease following the acute and chronic administration of salmon calcitonin. Plasma BGP was higher in women then in men with primary hyperparathyroidism. Following parathyroidectomy, BGP decreased in both sexes but the decrease was significant in women only. Plasma BGP was increased in patients with renal osteodystrophy and did not change after hemodialysis. In the patients with bone cancer, plasma BGP decreased during treatment of the attendant hypercalcemia with salmon calcitonin. Although plasma BGP and serum alkaline phosphatase (AP) levels were generally correlated in these studies, there were examples of dissociation between the two. The measurement of plasma BGP appears to provide a specific index of bone metabolism that may in some circumstances be more sensitive than serum alkaline phosphatase measurement. However, further studies are necessary to establish the clinical value of plasma BGP measurement by RIA in the management of patients with bone diseases.
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    Calcified tissue international 35 (1983), S. 107-110 
    ISSN: 1432-0827
    Keywords: Calcium ; Glucocorticoid ; Vitamin D ; Osteoporosis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Eighty-eight adult male Sprague-Dawley rats were given a diet with either (a) 0.5% Ca and 0.6% P or (b) 0.01% Ca and 0.6% P. Osteopenia was created by adding prednisolone to the diet. The prophylactic effect of oral 1,25(OH)2D3 on the osteopenia was studied. It was found that prednisolone osteopenia in the rat was associated with defective Ca absorption. By giving an oral dose of 1,25(OH)2D3, it was possible to maintain normal Ca absorption during prednisolone treatment and to prevent the bone loss. No significant hypercalcemia or any kidney calcifications were seen. These results are in contrast to earlier findings, in which subcutaneous administration of 1,25(OH)2D3 failed to prevent prednisolone osteopenia because of its tendency to increase bone resorption.
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  • 99
    ISSN: 1432-0827
    Keywords: 31P NMR spectroscopy ; Phosphoprotein ; Dentin ; Calcium ; Inorganic orthophosphate ; Bovine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The single phosphoprotein of fetal calf dentin, having a molecular weight of approximately 94,000 and a phosphorus content of 8% (w/w), was examined by31P NMR spectroscopy. The single resonance at 3.7 ppm at pH 10 and its chemical shift during acid titration established the phosphomonoester nature of the organic phosphorus moiety. During titration of the phosphoprotein with CaCl2 in the presence of inorganic orthophosphate ions, line broadening for the orthophosphate resonance was both phosphoprotein- and calcium-dependent, indicating ternary complex formation. The data indicate that the phosphoprotein of fetal calf dentin binds both calcium and inorganic orthophosphate ions and therefore has the requisite physical chemical properties necessary for it to facilitate the heterogeneous nucleation of a Ca-PO4 solid phase from solution during tissue mineralization.
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  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Planta 146 (1979), S. 31-39 
    ISSN: 1432-2048
    Keywords: Autoradiography ; Calcium ; Mougeotia ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ca2+ is proposed to function as a messenger in such phytochrome-mediated responses as localized cell growth, intracellular movements, and control of plasma membrane properties. To test this hypothesis, the uptake of Ca2+ in irradiated and non-irradiated regions of individual threads of the green alga Mougeotia was studied with the aid of 45Ca2+ and low temperature autoradiography: 10–20 cells within 40–60 cell-long threads were irradiated for up to 1 min, transferred to darkness for 3 to 10 min, submersed in a radioactive medium for 1 min, washed in an unlabelled medium for 30 min, and then autoradiographed at-80° C for several days. The autoradiographs show that those cells which had been pre-irradiated with red light did take up 2–10 times more Ca2+ than the adjacent non-irradiated cells of the same thread. Cells pre-irradiated with farred light or red light followed by far-red light showed no enhanced uptake of Ca2+. These results might be interpreted to indicate, firstly, that phytochrome-Pfr is involved in the enhanced uptake of Ca2+ and secondly, that the accumulation of radioactive Ca2+ in red light irradiated cells is an expression of an increased intracellular concentration of Ca2+. This interpretation is based on the data that (i) the dark interval between irradiation and labelling precluded the involvement of photosynthesis, (ii) the effect of red light was reversible with far-red light, and (iii) the accumulation of Ca2+ persisted during the long wash-out period. We speculate, that the red light-enhanced accumulation of Ca2+ in Mougeotia cells is caused by a Pfr-mediated increase of the Ca-permeability of the plasma membrane, and perhaps by a Pfr-impeding of an active Ca2+-extrusion.
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