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At least 1,063 records · Page 59Linked to original sources
PubMed1984

Senescent microstructural changes in rat cerebellum.

Senescent changes in Sprague-Dawley rat cerebellar microstructure have been quantified, focusing on the dominant element of cerebellar information processing, the Purkinje cell. In Golgi-Kopsch sections, many 26-month-old Purkinje cells appear defoliated, with small distal dendrites and spiny branchlets being most affected. The mean Purkinje cell area (soma plus dendrites) in computer-oriented sagittal sections is significantly decreased from 20,675 +/- 1,355 micron2/cell in 6-month-old rats to 17,088 +/- 1,107 micron2/cell in 26-month rats. These morphologic changes may be the hallmark of dying cells: in hematoxylin and eosin (H + E)-stained sections from the same rats we also observe a significant senescent decrease in Purkinje neuron density in every vermis lobule examined (lobules II-VII). Overall, the mean number of Purkinje cells/mm of Purkinje cell layer (measured in 10 micron thick sagittal sections) declines from 16.6 +/- 0.8 cells/mm in young rats to 12.5 +/- 0.2 cells/mm in old rats. As Purkinje cells are lost, so too are ethanolic phosphotungstic acid-stained (EPTA) synapses in the upper molecular layer of the cerebellar vermis (lobules VIII-X), and there is a highly significant within-subjects correlation between Purkinje cell density and synaptic density. Overall, synaptic density (in sagittal, 842 micron2 thin sections) decreases significantly from an average of 150,485 +/- 3,641 synapses/mm2 in 6-month rats to an average of 125,000 +/- 4,849 synapses/mm2 in 26-month rats. These changes are consistent with previous electrophysiologic and biochemical data showing age pathology of the cerebellum.

Aging↗
PubMed1987

Plasticity of the synaptic contact zone following loss of synapses in the cerebral cortex of aging humans.

Quantitative ultrastructural analyses of ethanolic phosphotungstic acid-stained human layer 1 precentral motor cortex (Brodmann's area 4) and layer 1 postcentral somatosensory cortex (Brodmann's area 3) were undertaken to determine the nature of synaptic changes occurring over a series of ages (45-84 years) of a normal aging human population. In the precentral cortex, a significant decrease in the number of synapses was accompanied by an increase in mean length of the postsynaptic contact zone and a decrease in the mean width of the presynaptic paramembranous density. The frequency of mature type A and immature type E synaptic profiles decreased with age. There were no changes in the width of the postsynaptic paramembranous density, cleft width or the number of presynaptic dense projections per synapse. In the postcentral cortex there were no significant changes in synaptic number or in any of the synaptic parameters measured. The present study demonstrates that age-related synapse loss in the human cerebral cortex may be confined to specific cortical regions. The data suggest that in the precentral cortex the plasticity of the synaptic contact zone may be a compensatory response by the remaining synapses to age-related synapse loss.

Aged↗
PubMed1992

Synaptic plasticity in the dentate gyrus of aged rats is altered after chronic nimodipine application.

We examined ultrastructural correlates of synaptic plasticity in the hippocampus of young (3 months) vs aged (30 months) Wistar rats and established the effects of the calcium antagonist nimodipine in animals chronically treated from 24 to 30 months. The effects of nimodipine was studied since this compound improves hippocampal neuronal physiology and enhances cognitive function during aging. In the supragranular layer of the dentate gyrus we found a 24% decrease in synaptic density (Nv) in aged animals, while synaptic size (S) was not significantly altered. After nimodipine treatment Nv in aged rats was not significantly different from young adults, thus being significantly increased compared to age-matched controls. The size of synapses was not significantly altered after nimodipine administration. Total synaptic surface area (Sv) in nimodipine-treated animals was significantly increased compared to aged controls, however, Sv remained significantly lower than in young adults. These data indicate that chronic administration of nimodipine enables granular cells in the dentate gyrus to maintain its number of synaptic contacts during the aging process. Furthermore, the presented influence of nimodipine on synaptic plasticity processes may underlie previously reported improved cognitive functioning of aged animals treated similarly with nimodipine.

Aging↗
PubMed1979

Rapid development of immunoprecipitins in agarose gel.

A procedure for the rapid development of immunoprecipitins in agarose gels has been developed using polyanion precipitation after immunoelectrophoretical separations. Excellent results are obtained for serum apolipoproteins, immunoglobulins and other proteins. It is shown that quantitative determination of apolipoprotein B in hyperlipemic serum and isolated lipoproteins is affected by immunoprecipitated complexes when rocket immunoelectrophoresis is used. This effect can be avoided by addition of polyvinylpyrrolidone.

Apolipoproteins↗
PubMed1981

A lipoprotein independent assay for human serum lecithin-cholesterol acyltransferase.

A method has been developed for estimation of human serum lecithin-cholesterol acyltransferase free of interference by endogenous lipoproteins. Precipitation of serum low and very low density lipoproteins by sodium phosphotungstate and magnesium chloride results in complete recovery of lecithin-cholesterol acyltransferase activity in the supernatant. One microliter of the supernatant can be accurately assayed with a highly efficient substrate containing phosphatidylcholine-cholesterol vesicles and apo-high density lipoproteins (HDL), with no interference from endogenous HDL or residual precipitation reagents. Serum levels of the enzyme were found to be reduced in patients with parenchymal liver disease, renal disease, gastrointestinal tumors and anemias.

Disease↗
PubMed1982

Total automated method for determination of cholesterol concentration in high density lipoprotein by heparin-magnesium-albumin precipitation.

We describe an automated procedure for determination of high-density-lipoprotein cholesterol in serum by use of heparin-MgCl2-albumin reagent. 'AutoAnalyzer' II equipment was used in which high-density lipoprotein was separated from precipitate containing very-low and low-density lipoproteins by filtering on-line across a cellulose acetate membrane. Cholesterol concentration was measured by the enzymic method of Allain. Good correlation was obtained using the automated method compared to the heparin-MgCl2-albumin (r=0.99) or sodium phosphotungstate-MgCl2 procedure (r=0.97). Contamination was minimal with a contamination coefficient lower than 2.5%. The method presented was linear (0 to 2.50 mmol/1) and could be applied to lipemic samples with a coefficient of variation better than 3%. This study showed thus that this new procedure was suitable for routine work with a good rate (60 samples/h) in almost any laboratory.

Autoanalysis↗