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  • Articles  (80)
  • Electron microscopy  (46)
  • hypertension  (19)
  • Development  (17)
  • Springer  (80)
  • American Chemical Society (ACS)
  • 1980-1984  (80)
  • 1980  (80)
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  • Articles  (80)
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  • 1980-1984  (80)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 188 (1980), S. 55-63 
    ISSN: 1432-041X
    Keywords: Drosophila ; Compound eye ; shibire ts ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analysed the effect of temperature on both developing and adult eye cell clones homozygous forshi ST139, a temperature-sensitive mutant ofDrosophila melanogaster. The mutant gene, autonomous in its cellular expression, causes structural modifications of ommatidial cells when adult clones of cells are exposed to the restrictive temperature (29°C) for several days. However, the mutant phenotype reverses to normal within 4 days at the permissive temperature (20°C). The results of pulse, shift-up and shift-down experiments show that the temperaturesensitive period for developing compound eye cells is from the late second instar up to the early pupa. Cytodifferentiation of compound eye cells is blocked by restrictive temperature treatment during this period, whereas cell proliferation does not seem to be directly affected. These results are discussed with regard to the other known aspects of the phenotype observed in mutant individuals.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 188 (1980), S. 205-213 
    ISSN: 1432-041X
    Keywords: Gangliosides ; Development ; Brain ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The developmental profiles of 15 different gangliosides of the optic lobes and cerebrum of the chicken were followed from the 6 th day of incubation to hatching and correlated to morphological development. Five of these gangliosides appearing in both structures between the sixth and tenth day, have not been reported previously in higher vertebrates. Three chromatographed on TLC-plates similarly to GT3, GT2, and GT1c gangliosides, which have been demonstrated in fish brain. One fraction moved just below GQ1b and is suggested, to contain GQ1c. These “novel” gangliosides, which are possibly related to a recently proposed separate and probably phylogenetically older biosynthetic pathway, contained up to 20% of total ganglioside sialic acid. The fifth “novel” fraction, containing up to 16% of total ganglioside-sialic acid, moved below the penta-sialoganglioside GP1 and is suggested to contain hexa-sialogangliosides. There were two main changes in ganglioside synthesis, which were identical in both structures. The first occurred from the sixth to the eleventh day, parallel to decreased proliferation, maximal cell migration and neuroblast differentiation, GD3 and GD2 decreased rapidly in favour of GQ1b, GP1, and to the “novel” fractions, described above. The second occurred from the eleventh to the eighteenth day, parallel to increased growth and arborization of dendrites and axons as well as functional establishment of synaptic contacts, there was a sharp rise in the amount of GD1b, GT1b, and GD1a. Concomitantly the “novel” gangliosides decreased. At hatching GD1a was the predominant ganglioside. GM3, GM2, and GM1 were always minor fractions, each accounting for less than 4% of total ganglioside-sialic acid. GM4 was never detected, indicating neglegible myelinisation until hatching.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 189 (1980), S. 171-180 
    ISSN: 1432-041X
    Keywords: Amino acyl-tRNA synthetases ; Development ; Nuclear-mitochondrial interactions ; Neurospora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The specific activities of the branched chain amino acyl-tRNA synthetases from the cytosolic and mitochondrial fractions ofN. crassa were low in dormant conidia and increased during germination, reaching a maximum 8 h after inoculation. This stage of development is characterised by high rates of many other cellular activities. The increases in activity of synthetases of both cytosol and mitochondria are inhibited by cycloheximide indicating that they are synthesized on cytoplasmic ribosomes. The mitochondrial synthetases show a stimulation of their specific activity when mitochondrial RNA and protein synthesis are inhibited by either ethidium bromide or chloramphenicol suggesting that a mitochondrial translation product regulates the synthesis of the mitochondrial synthetases. The activities of amino acyl-tRNA synthetases are dependent on energy production. When respiration is uncoupled from oxidative phosphorylation, synthetase specific activities decrease although the activities of other mitochondrial enzymes like NADH-dehydrogenase increase. This phenomenon suggests that more than one mechanism regulates the synthesis of mitochondrial proteins which are formed on cytoplasmic ribosomes. The synthesis of branched chain amino acyl-tRNA synthetases ofNeurospora is neither repressed by their cognate amino acids, nor is there inhibition by the precursors of these amino acids, as has been observed in other amino acyl-tRNA synthetases of various organism includingNeurospora.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 30 (1980), S. 43-50 
    ISSN: 1432-0827
    Keywords: Osteogenesis ; In vitro ; Electron microscopy ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    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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  • 5
    ISSN: 1432-0827
    Keywords: Rat ; Calvarium ; Electron microscopy ; Preosteoclasts ; Osteoclasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    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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  • 6
    ISSN: 1432-0827
    Keywords: Decalcification ; Electron microscopy ; Bone matrix ; Bone glycoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    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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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 18 (1980), S. 321-326 
    ISSN: 1432-1041
    Keywords: sotalol ; hypertension ; renal impairment ; chronic administration ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Ten hypertensive patients with moderate to severe impairment of renal function were treated with sotalol for 5 to 10 weeks (average 6.4 weeks). Dosage was individually titrated (range 80 to 480 mg daily). The drug was given once daily in the morning. In eight patients blood pressure was satisfactorily controlled. Higher steady-state levels were observed than have been reported after similar doses in patients with normal renal function. The apparent first-order elimination rate constant and plasma clearance were significantly correlated with glomerular filtration rate. For an anuric patient, serum half-life was calculated to be 69 h. In relation to the raised plasma levels, side effects were uncommon. Since sotalol is excreted predominantly via the kidney, therapy in patients with impaired renal function should start with a low dose and any increase in dosage should be made carefully. As the anti-hypertensive effect does not appear to be correlated with the plasma level or with tolerance, adjustment of dose should be based on clinical response.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 18 (1980), S. 225-229 
    ISSN: 1432-1041
    Keywords: metoprolol ; hypertension ; slow-release preparations ; maximal exercise power ; fatigue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The treatment of hypertension with a single daily-dose of a beta-blocker gives rise to high peak-plasma concentrations 1.5 h after ingestion. After slow release-preparations of beta-blockers, the peak concentrations are half those produced by the conventional preparation at the same oral dose. A frequently occurring side-effect of beta-blocker therapy is fatigue. In this study the effect of a single dose of metoprolol 300 mg, 200 mg, 200 mg slow-release and a placebo on maximal exercise power was tested in 6 healthy subjects, 1.5 h and 24 h after ingestion. Maximal exercise power was significantly reduced 1.5 h after ingestion of metoprolol 300 mg and 200 mg. No change was found 1.5 h after 200 mg of a slow-release preparation. The possible reasons for reduced maximal exercise power are discussed. It is concluded that use of a beta-blocker for the treatment of hypertension in a single daily-dose regimen may be a reason to prefer a slow-release preparation.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 18 (1980), S. 399-401 
    ISSN: 1432-1041
    Keywords: prazosin ; hypertension ; central monoaminergic neurons ; monoamine metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Six hypertensive patients were treated with prazosin up to a final dose of 3–4.5 mg/day. There was a significant reduction of blood pressure. The cerebrospinal fluid (CSF) concentrations of the major metabolites of noradrenaline, dopamine and serotonin were unchanged. This indicates that the antihypertensive effect is not mediated via central monoaminergic neurons as suggested by animal studies.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 18 (1980), S. 105-108 
    ISSN: 1432-1041
    Keywords: renin ; angiotensin ; aldosterone ; hypertension ; hypoaldosteronism ; pseudohypoaldosteronism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary There is increased activity of the renin, angiotensin, aldosterone (RAA) system in infancy and childhood. An inverse relationship between plasma renin, aldosterone and age has been demonstrated. In childhood hypertension due to renovascular disease or pyelonephritic scarring peripheral plasma renin is increased. Renal vein renin measurements in children with renal hypertension have proved valuable in predicting surgical curability of the underlying lesion. The upper limit of normal for the renal venous renin ratio in normotensive children without renal disease is 1.5. Pharmacological blockade of the RAA system has a place in diagnosis and treatment of hypertensive children. The plasma renin aldosterone profile is diagnostically useful in the investigation of salt-wasting disease and can easily distinguish between aldosterone biosynthetic defects and pseudohypoaldosteronism.
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