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At least 595 records · Page 33Linked to original sources
PubMed1991

Morphological changes in unmyelinated nerve fibres in the sural nerve with age.

Quantitative changes in unmyelinated nerve fibres in sural nerves obtained at autopsy were evaluated in 28 normal adults. The following conclusions were reached. (1) The density of unmyelinated axons showed no significant correlation with age, but the densities of (2) Schwann cell subunits with axons, (3) Schwann cell subunits without axons, (4) single protrusions of Schwann cells and (5) collagen pockets, and (6) the mean number of Schwann cell profiles per axon, all showed positive correlations with age. Additionally, (7) the percentage of subunits containing unmyelinated axons and (8) the mean number of axons in single axon-containing Schwann cell subunits demonstrated negative correlations with age. The density of Schwann cell nuclei related to unmyelinated fibres did not show a significant change with age. The age-dependent changes in unmyelinated nerve fibres thus mainly consist of an increased production of processes by Schwann cells in the absence of cell multiplication. A decrease in unmyelinated nerve fibre density or a compensatory increase of small unmyelinated axons did not occur in these normal adults. In terms of relative sensitivity for the detection of the earliest changes in unmyelinated fibres, the indices (6) and (7) are considered to be useful and superior to the conventional assessment of unmyelinated axon density and diameter distribution. These two indices are not influenced by postmortem swelling of the axons and Schwann cells. Measurements of unmyelinated axon density and size distribution will continue to be useful in the assessment of more advanced pathological conditions.

Adult↗
PubMed1997

Pathological studies of wobbly possum disease in New Zealand brushtail possums (Trichosurus vulpecula).

Following an outbreak of wobbly possum disease in a colony of brush tail possums (Trichosurus vulpecula), the disease was established experimentally in captive possums by inoculating the animals intraperitoneally with tissue homogenates. Crude tissue homogenates of liver remained infectious after freezing at -75 degrees C or filtration through a 0.22 micron filter. The disease was characterised by docility, incoordination, loss of balance and wasting. Fifteen of 16 infected animals had to be euthanased owing to the severity of clinical signs. Cachexia was the only change observed postmortem. Histology revealed widespread perivascular infiltrations with plasma cells and lymphocytes which were severe in the liver and kidney and moderate to mild in a variety of other tissues, including skeletal and cardiac muscle. Changes in the brain consisted of a mild to moderate mononuclear perivascular cuffing. Most of the animals had small to large numbers of circulating nucleated red blood cells and eosinopenia when they were euthanased. There was a consistent decrease in serum albumin concentration and an increase in serum globulins, which resulted in a decreased albumin:globulin ratio. Virus-like particles were observed in preparations of liver from two animals; they appeared to be spherical or icosahedral and were 45 nm in diameter.

Animals↗
PubMed2002

Differential skeletal preservation at Windover Pond: causes and consequences.

In this paper, we evaluate the causes of differential skeletal preservation in the Windover Pond skeletal series (8BR246). We collected data on sex and age for approximately 110 individuals, and calculated a preservation score for each individual based on the presence of 80 skeletal landmarks. Our research questions evaluated the relationship between bone preservation and individual age and sex, and between the presence of preserved brain material and skeletal preservation, and the effects of burial location on bone preservation. The results indicate variability in average preservation for the sample (micro = 0.53, SD = 0.22) with an apparent lack of sex-specific (P = 0.79) or age-specific (P = 0.37) differences in preservation. The relationship between brain and skeletal preservation (P = 0.15) was not significant. The horizontal distribution of burials was not significantly correlated with skeletal preservation (north: r = -0.10, P = 0.93; east: r = 0.09, P = 0.45); however, vertical depth was a significant predictor of preservation (r = -0.31, P = 0.005), indicating that skeletal preservation decreased as burials were located closer to the ground surface. The observed variability in preservation scores may be related to the partial drying and resubmergence of the uppermost burials for the last few millennia. Comparison of Windover element-specific survival rates with previous analyses based on terrestrial samples (Galloway et al. [1997] Forensic taphonomy, Boca Raton: CRC Press; Waldron [1987] Death, decay and reconstruction, Manchester: Manchester University Press; Willey et al. [1997] Am J Phys Anthropol 104:513-528) affirms the relationship between element weight or density and bone survival. The unique taphonomic context of our study sample effected little change in bone deterioration processes.

Age Factors↗
PubMed1987

Autolytic changes of human white matter: an electron microscopic and electrophoretic study.

The effect of autolysis on the electrophoretic pattern of the 3H-labeled membrane glycoproteins derived from human brain white matter (WM) was investigated and correlated with electron microscopic findings. Samples were taken from the WM of outer zones of routine surgical specimens sent for pathologist's examination. The WM samples were incubated at +4 and +25 degrees C for 6 and 24 hr and analyzed by electron microscopy and by galactose oxidase labeling with subsequent SDS-polyacrylamide gradient gel electrophoresis. The effect of freezing and thawing was also studied. In electron microscopic examination myelin was found to have degenerated after an incubation of 24 hr at +4 and +25 degrees C, and it was severely disrupted after 24 hr at +25 degrees C, when a periaxonal network-like change was observed. The major labeled membrane glycoprotein band with an estimated molecular weight (MW) of 138,000 was stable during the first 24 hr of incubations at both +4 and +25 degrees C. No marked changes were noticed in the electrophoretic pattern of all of the WM membrane proteins labeled by [3H]acetic anhydride technique. In frozen and thawed specimens there was an increase in the intensity of the band with a MW of 86,500 and a new band appeared at the MW region of 25,000. The present results suggest that despite the apparent stability of the major glycoprotein band during the first 24 hr of autolysis, there are ultrastructural abnormalities in the myelin sheath, which should be taken into consideration during interpretation of changes in pathologic conditions.

Autolysis↗
PubMed1975

A comparative enzyme histochemical and histological study of the effect of ischaemia and post mortem change on rat kidneys.

A histochemical study of the effect of ischaemia on rat kidneys showed that changes were demonstrable in adenosine triphosphatase, alkaline phosphatase and succinic dehydrogenase within 2 h. Further changes occurred with increasing time. The activity of acid phosphatase was little affected up to 24 h although at this time there was marked tubular disruption. Paraffin embedded H and E sections also showed marked changes within 2 h. Enzyme histochemical and histological changes in kidneys taken at varying periods after the death of the animal showed very similar changes to those in ischaemic kidneys. Differences were mainly in the rate and extent of the changes.

Acid Phosphatase↗
PubMed1980

[Influence of below-freezing temperatures on the rate of post-mortem metabolism and the water-holding capacity in prerigor frozen beef muscles (author's transl)].

Prerigor beef is very suitable for the production of "bruehwurst" (frankfurter and bologna type sausages) because of its high waterholding capacity (WHC). This high WHC can be preserved for several months by rapid freezing of prerigor beef either unsalted or salted. In order to elucidate the optimum conditions of frozen storage for the preservation of high WHC, intact beef muscle, ground beef and ground, salted (2% NaC1) beef (neck muscles) were frozen at - 18 degrees or --40 degrees C in a thin layer (0.5-1 cm) 30--60 min after slaugther and stored at various temperatures between --5 degrees and --40 degrees C. The changes of biochemical parameters (content of glycogen and lactate, R-value [it corresponds to ATP concentration] and pH) in the tissue and the WHC of raw and heated muscle homogenates, prepared from the frozen material and containing 2% NaC1, were measured and related to time and temperature of frozen storage. At storage temperature of --18 degrees and --40 degrees C no appreciable biochemical changes occur in intact and ground, unsalted tissue over a period of 10 months. Above 18 degrees C, however, rising temperature causes an increased rate of ATP turnover and glycolysis. In ground muscle higher rates of postmortem metabolism are generally found than in the intact tissue. In prerigor salted and frozen beef a faster drug of ATP concentration (increase of R-value) occurs whereas the breakdown of glycogen to lactate is inhibited. The WHC of raw and heated muscle homogenates depends on time and temperature of frozen storage. As soon as the ATP concentration in unsalted beef falls to a level, at which the onset of rigor mortis occurs, the WHC of homogenates decreases markedly. With beef, ground and salted in the prerigor state and than frozen muscle homogenates are obtained which show always a high WHC even after complete breakdown at ATP during frozen storage. These results have practical consequences with regard to processing of hot-deboned beef.

Adenosine Triphosphate↗
PubMed1991

Diminished synaptosomal dopamine (DA) release and DA autoreceptor supersensitivity in schizophrenia.

Post-mortem brain regions of schizophrenics were investigated in comparison to matched controls regarding synaptosomal K(+)-stimulated [3H]DA release and its modulation by DA autoreceptors. Brain specimens were cryopreserved in liquid nitrogen until release experiments; synaptosomes from brain pieces preincubated with dimethylsulfoxide have unchanged ability for [3H]DA release and its autoreceptor-mediated inhibition after cryo-preservation. Release data were individually corrected for post-mortem delay back to the zero-time state based on [3H]DA release alterations after in situ preservation of rat heads. In schizophrenia, the K(+)-stimulated [3H]DA release from superfused synaptosomes of the nucleus (n.) accumbens and n. caudatus was diminished significantly. Furthermore, functional supersensitivity of the modulatory DA autoreceptors could be demonstrated in these regions. The alterations demonstrated seem not to be due primarily to medication since in neuroleptic-free patients similar changes were shown.

Amygdala↗
PubMed1996

Immunohistochemical detection of rinderpest virus: effects of autolysis and period of fixation.

Samples of eyelid, tongue, soft palate and palatine tonsil were collected from calves infected experimentally with rinderpest virus. The tissues were fixed in 10 per cent neutral buffered formalin immediately, 24 or 48 hours post mortem. Then, after three days, 10 days, 28 days or three months in formalin, they were processed into paraffin blocks and examined immunohistochemically for rinderpest viral antigen. The tonsil was the best of the four tissues in providing a consistently positive immunohistochemical signal for the presence of virus, despite autolytic changes and/or prolonged fixation.

Animals↗
PubMed2003

Proteome analysis elucidating post-mortem changes in cod (Gadus morhua) muscle proteins.

Proteome analysis was successfully applied to study the alterations in fish muscle proteins during ice storage. The processes occurring during post-mortem metabolism are known to lead to characteristic changes in the texture and taste of fish muscle. Endogenous proteases are anticipated to play the major role in these processes, although the exact mechanisms during fish meat tenderization have yet to be depicted. Protein changes in cod (Gadus morhua) muscle were followed during 8 days of storage. Within the partial proteome (pI 3.5-8.0, MW 13-35 kDa) significant changes were found in 11 protein spots. In nine protein spots the intensity increased, and for eight of these the increases were significant (p < 0.05) within the first 2 h post-mortem. In contrast, two protein spots decreasing in intensity showed significant (p < 0.03) changes after 8 days, thereby indicating that in the fish muscle different biochemical processes are involved in the protein changes observed post-mortem.

Adenosine Triphosphate↗