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  • Rats  (1,045)
  • American Association for the Advancement of Science (AAAS)  (1,018)
  • Springer  (27)
  • Blackwell Publishing Ltd
  • Elsevier
  • Emerald
  • International Union of Crystallography
  • Wiley
  • 1995-1999  (338)
  • 1980-1984  (704)
  • 1970-1974  (3)
Collection
Keywords
Publisher
  • American Association for the Advancement of Science (AAAS)  (1,018)
  • Springer  (27)
  • Blackwell Publishing Ltd
  • Elsevier
  • Emerald
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Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Use of public information when foraging: effects of time available to sample foods (1999)
    Springer
    Animal cognition 2 (1999), S. 103-107 
    Details
    ISSN: 1435-9456
    Keywords: Key words Social learning ; Temporal constraints ; Public information ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It has been proposed that use of socially acquired information by animals should increase as the time available for individual resource sampling decreases. We gave Norway rat “observers” either 2 or 5 h day–1 to sample four foods. Three of these foods were relatively palatable, but protein-poor; the fourth was relatively unpalatable, but protein-rich. We found that observer rats that for 2 h day–1 both sampled foods and interacted with demonstrators eating only the protein-rich food ate more of the protein-rich food than did observers that sampled for 2 h day–1 but had no opportunity to interact with demonstrators. On the other hand, observer rats that could sample foods for 5 h day–1 ate equal amounts of protein-rich food whether they interacted with a demonstrator fed protein-rich food or not. Subsequent analyses showed that the time available to observers to sample foods, rather than the opportunity to interact with demonstrators determined whether such interaction influenced observers’ food choices. The results are consistent with the hypothesis that animals increase their use of public information in response to temporal constraints on opportunities for resource sampling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100710050030
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  • 2
    Electronic Resource
    Electronic Resource
    Immobilization osteoporosis and active vitamin D: Effect of active vitamin D analogs on the development of immobilization osteoporosis in rats (1981)
    Springer
    Calcified tissue international 33 (1981), S. 623-630 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Immobilization ; Rats ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The therapeutic effects of vitamin D analogs, 1,24(R)-dihydroxycholecalciferol [1,24(R)(OH)2D3], 1,24(S)-dihydroxycholecalciferol [1,24(S)(OH)2D3], and 1,25-dihydroxycholecalciferol [1,25(OH)2D3] on immobilization osteoporosis were studied in rats. The right hind limb was immobilized through application of a plaster cast following the section of the sciatic nerve. The left hind limb was intact. Vitamin D analogs were orally administered for 6 weeks at dose levels of 0.02 and 0.10µg/kg/day, respectively. The mean lengths of the immobilized femurs were not significantly different from those of the intact femurs in all the experimental groups. In the immobilized femur of animals treated with 1,24(R)(OH)2D3, 0.10µg/kg, dry and ash weights were heavier and calcium and phosphorus contents greater than those in the nontreated group. Furthermore, the amount of calcified bone mass and the cortical thickness of the femurs of the immobilized limb in 1,24(R)(OH)2D3-treated animals were greater than those in the nontreated animals. Treatment with 1,25(OH)2D3 at 0.10µg/kg caused an increase of the bone mass in both immobilized and intact femurs when compared with those of the control group. It was concluded that the administration of 1,24(R)(OH)2D3 diminished the effect of immobilization in the development of osteoporosis without any side effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409500
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  • 3
    Electronic Resource
    Electronic Resource
    Scanning electron microscopy of castrate rat bone (1982)
    Springer
    Calcified tissue international 34 (1982), S. 547-552 
    Details
    ISSN: 1432-0827
    Keywords: Rats ; Osteoporosis ; Anorganic ; Femur ; Castrate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The study describes the SEM appearances of endosteal and periosteal surfaces of anorganic femoral diaphyses from 16-month-old normal and castrate male rats. Different types of surfaces could be recognized in both groups. Percentage areas occupied by each surface type were analyzed with a Ladd Data Analyzing Digitizer. Endosteal surfaces were composed of significantly more (P〈0.05) incompletely mineralized, forming surface and significantly less (P〈0.05) completely mineralized, resting surface in castrates than in controls. Both endosteal and periosteal surfaces from experimental bone demonstrated significantly more (P〈0.05) osteoblast lucunae than did control surfaces, and vascular canal entrances were significantly wider (P〈0.001) on castrate endosteal surfaces than on control endosteal surfaces. There was a greater proportion of small nodule forming surface/large nodule forming surface in castrate endosteal bone than in control, and a greater proportion prolonged resting surface/fibrous resting surface in control periosteal bone than in castrate. The results indicate that, when viewed in the SEM, anorganic endosteal and periosteal bone surfaces from femoral diaphyses of old castrate male rats demonstrate appearances characteristic of changes in bone turnover that occur with osteoporosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411302
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  • 4
    Electronic Resource
    Electronic Resource
    Localized, multiform, sub-periosteal hyperplasia and generalized osteomyelosclerosis in magnesium-deficient rats (1972)
    Springer
    Calcified tissue international 9 (1972), S. 17-27 
    Details
    ISSN: 1432-0827
    Keywords: Periosteal Hyperplasia ; Osteomyelosclerosis ; Magnesium ; Parathyroid ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un régime contenant 0.8 à 2 mg de Mg pour 100 g, administré à des rats jeunes ou adultes pendant 18 à 21 jours, provoque une croissance généralisée d'os médullaire (ostéomyélosclérose), ainsi que des tumeurs périostées de type desmoide, au niveau de la linea aspera du fémur. Ces modifications s'accompagnent d'une décroissance du magnésium osseux de 52 à 71%, déterminée par spectrophotométrie d'absorption atomique. Au niveau des tumeurs périostées, la parathyroidectomie favorise la formation de cartilage. L'administration d'extrait parathyroidien inhibe la formation de cartilage en faveur de la formation de tissue fibreux et d'os. L'adjonction de magnésium au régime restitue rapidement l'apparence normale des tissus.
    Abstract: Zusammenfassung Eine Nahrung mit 0,8–2 mg Mg per 100 g wurde jungen oder ausgewachsenen Ratten während 18–21 Tagen verfüttert; sie verursachte ein generalisiertes medulläres Knochenwachstum (Osteomyelosklerose) und ebenso desmoidartige Tumoren, des Periosts an der femoralen Linea aspera. Diese Veränderungen waren von einer Abnahme von 52–71% der Magnesium-Konzentration im Knochen begleitet (Bestimmung am Atomabsorptions-Spektrophotometer). Bei Tumoren des Periosts wurde die Knorpelbildung durch Parathyreoidektomie begünstigt. Durch Verabreichung von Parathyreoidea-Extrakt wurde die Knorpelbildung gehemmt und an deren Stell fibröses Gewebe und Knochen gebildet. Wurde der Nahrung Magnesium zugesetzt, so bekamen die Gewebe rasch ein normales Aussehen.
    Notes: Abstract A diet containing from 0.8 to 2 mg Mg/100 g, fed to young or adult rats for 18 to 21 days produced generalized medullary bone growth (osteomyelosclerosis) and also periosteal tumours of the desmoid type, at the femoral linea aspera. These changes were accompanied by decreases in bone magnesium concentration of 52 to 71% as measured by atomic absorption spectrophotometry. In the periosteal tumours, parathyroidectomy favoured cartilage formation. The administration of parathyroid extract inhibited cartilage formation in favour of fibrous tissue and bone production. The addition of magnesium to the diet quickly restored the normal appearance of the tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02061942
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of penitrem A on rat's performances in passive avoidance and Morris water maze tests (1997)
    Springer
    Mycopathologia 138 (1997), S. 99-104 
    Details
    ISSN: 1573-0832
    Keywords: Learning ; Memory ; Morris water maze ; Passive avoidance ; Penitrem A ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Intraperitoneal administration of the mycotoxin penitrem A 30 min before a training session in passive avoidance task, impaired performance of rats subjected to a test-session 24 h after. This effect was not antagonised by pretraining administration of physostigmine or bicuculline. Administration of penitrem A 20 min before a training session or 30 min before a test-session did not impair performance. In the Morris water maze, doses of penitrem A that induces slight to moderate tremors, but not a lower dose, disrupted place learning. These results suggest that penitrem A disrupts the processes that take place at the time of acquisition, but not those just after acquisition, and does not alter the restitution of information. This effect would not be related to a decrease of cholinergic neurotransmission nor to a stimulation of GABA A receptors. Nevertheless, it could not be totally excluded that the performance impairments induced by penitrem A would be secondary to a motor disruption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006853600205
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  • 6
    Electronic Resource
    Electronic Resource
    Recombinant bone morphogenetic protein-2 enhances bone healing, guided by osteopromotive e-PTFE membranes: An experimental study in rats (1995)
    Springer
    Calcified tissue international 56 (1995), S. 549-553 
    Details
    ISSN: 1432-0827
    Keywords: Bone development ; Bone morphogenetic protein ; Artificial membrane ; Polytetrafluoroethylene ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract It has been shown earlier that it is possible to improve bone healing, to regenerate previously existing bone, and to create new bone by means of an osteopromotive membrane technique. The present study addresses the question of whether it is possible to combine this technique with a locally applied factor, stimulatory to osteogenesis. Circular transosseous ‘critical size’ defects in mandibles of rats were either implanted with recombinant human bone morphogenetic protein type 2 (rhBMP-2) or were left empty; half the number of implanted and half the number of empty defects were covered with an expanded polytetrafluoroethylene (e-PTFE) membrane (GORE-TEX®). Results were evaluated after 12 and 24 days of healing by a histomorphological scoring system. Implantation of rhBMP-2 alone resulted in bony bridging of the defect after only 12 days, but also in voluminous amounts of new bone outside the original defect area. When rhBMP-2 was combined with membrane, newly formed woven bone bridged the defect and the bone contour was maintained by the membrane. The combined treatment with membrane and rhBMP-2 demonstrated a significantly better bone healing than with e-PTFE membrane alone at both 12 days and 24 days of healing. It was concluded that rhBMP-2 has a strong osteoinductive potential and, in contrast to what was found earlier with other types of BMP preparations, this potential was retained when combining the rhBMP-2 with the osteopromotive membrane technique, yielding better bone healing than with the membrane alone, and at the same time maintaining the bone contour. This combination may have important therapeutic applications for osseous healing and in reconstructive surgery. The study also shows the importance of an appropriate carrier material when applying stimulatory substances to enhance bone formation in combination with a membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298588
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  • 7
    Electronic Resource
    Electronic Resource
    Use of dermestid beetles for cleaning bones (1980)
    Springer
    Calcified tissue international 31 (1980), S. 45-47 
    Details
    ISSN: 1432-0827
    Keywords: Dermestid beetles ; Cleaning bones ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Various parts of the skeleton of normal and osteoporotic rats were compared with respect to their dry weight, ash weight, and calcium content when the bones were cleaned byDermestes maculatus beetles or manually. Both techniques gave similar results. This was also true when whole body calcium measured by neutron activation and total skeletal calcium from bones cleaned by the beetles were compared. Thus dermestid beetles are useful as a technique to clean bones, especially for the parts of the skeleton which are difficult to dissect by hand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02407166
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of castration on the bone structure of male rats: A model of osteoporosis (1980)
    Springer
    Calcified tissue international 32 (1980), S. 77-82 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Castration ; Density ; Femur ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Forty young (23-day-old) and thirty old (1-year-old) male rats were castrated and sacrificed with controls at intervals up to 18 months of age. No differences were observed between femurs or mandibles of rats castrated at 23 days and those of controls. Year-old castrate rats developed femoral osteoporosis after 2 months, which became more pronounced 4 months after castration. This was characterized by reductions in femoral density, dry weight, dry weight per unit length, and ash weight, and by the appearance of resorption cavities in diaphyseal walls and a sparsity of trabeculae in metaphyses and epiphyses of castrate femurs. These results indicate that the year-old castrate male rat may be a valuable experimental model for studies of the treatment of osteoporosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408524
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  • 9
    Electronic Resource
    Electronic Resource
    Role of parathyroid hormone and 1,25-dihydroxyvitamin D3 in the development of osteopenia in oophorectomized rats (1982)
    Springer
    Calcified tissue international 34 (1982), S. 510-514 
    Details
    ISSN: 1432-0827
    Keywords: Rats ; Osteopenia of oophorectomy ; 1,25-Dihydroxyvitamin D3 ; Parathyroid hormone ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effect of ovarian insufficiency on calcium metabolism has been thought to involve an increased bone resorptive effect of parathyroid hormone and possible impaired synthesis of 1,25-dihydroxyvitamin D3. In the present study a rat model allowing for controlled serum levels of parathyroid hormone and 1,25-dihydroxyvitamin D3 was used. Oophorectomy in this species is associated with increased serum levels of 1,25-dihydroxyvitamin D3 and decreased bone mass. Although thyroparathyroidectomy increased bone mass, an increased sensitivity of bone to parathyroid hormone in oophorectomized rats was not observed. Thus the development of the osteopenia did not seem to be related to increased parathyroid hormone sensitivity or to reduced levels of 1,25-dihydroxyvitamin D3. Exogenous 1,25-dihydroxyvitamin D3 increased bone mass in oophorectomized as well as intact rats. Intestinal calcium transport was increased by moderate doses of 1,25-dihydroxyvitamin D3. Intestinal calcium transport was also reduced by thyroparathyroidectomy and increased by the administration of parathyroid extract. A tendency for increased accumulation of 1,25-dihydroxyvitamin D3 in blood in oophorectomized rats has been noted. It is suggested that the tendency to hypercalcemia in ovarian-insufficient females given 1-hydroxylated vitamin D compounds may be related to a diminished metabolism of 1,25-dihydroxyvitamin D3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02411294
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  • 10
    Electronic Resource
    Electronic Resource
    A comparative study on the occurrence and activity of extracellular matrix vesicles in young and adult rat maxillary bone (1981)
    Springer
    Calcified tissue international 33 (1981), S. 129-134 
    Details
    ISSN: 1432-0827
    Keywords: Matrix vesicles ; Young/adult ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The occurrence of matrix vesicles in the maxillary bone of normal young and adult rats was demonstrated by both ultrastructural and enzymatic studies. Transmission electron microscopy revealed that the vesicles are invested in trilaminar membranes. Occasionally, crystals were found both within the vesicles and in the surrounding matrix. Separated fractions of vesicles, membranes, and cells were studied biochemically. The amounts of vesicular protein and enzymatic activity per gram bone in the adult rats were significantly lower than in the young. This coincides with the higher number of vesicles observed in the TEM specimens of young rats when compared to that in the old ones. The specific activities of all enzymes examined in the three bone fractions obtained from both young and adult rats were similar. This indicates that no significant difference exists in the enzymatic characteristics of matrix vesicles from the maxillary bone of young and adult rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02409425
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