Biomedical subjects
Publications and source records attributed to M A Verity.
A case with extramedullary ependymal cyst of the spinal cord is presented. The clinical, operative, and pathological findings are discussed and a review of previous cases and a nosologic classification of ependymal lined cysts given.
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Studies of mitochondrial respiratory control and swelling contraction activity during early cell regeneration after partial hepatectomy have revealed a selective defect in the rate of substrate-supported, phosphate-induced mitochondrial swelling. Swelling profiles induced by Fe(2-) or Cu(2-) revealed no differences between sham-operated and partially hepatectomized mice, which suggests no defects in -SH group composition or ability to form lipid peroxides. The specific activity of mitochondrial cytochrome c oxidase was unchanged. There was no significant mitochondrial swelling in situ as determined from mitocrit and mitochondrial protein ratios. A significant decline in respiratory control and efficiency of oxidative phosphorylation was found in mitochondria from animals 8 and 24 hours after partial hepatectomy, partially reversed by bovine serum albumin. No significant change in ADP:O ratio was noted and the decrease in RCI was due primarily to a significant decline in state 3 respiration rate. In situ electron microscopic studies of mitochondria failed to reveal significant abnormalities during early cell regeneration apart from decrease in numbers of matrix granules, focal matrix rarefaction and predominance of round forms. Electron microscopic studies of mitochondria after in vitro phosphate-induced swelling experiments showed no differences between sham and partially hepatectomized animals, but revealed two distinct populations of mitochondria, the predominant form (type III) showing distortion, matrix lucency and outer membrane rupture. ATP induced a diminished reversal in light scattering in partially hepatectomized mitochondria even when examined at 20 minutes, manifested as an increase in numbers of orthodox mitochondrial forms at the expense of the swollen type III forms. The pathogenesis of the impaired respiratory control and phosphate-induced swelling is unknown, but analogous observations have been found in mitochondria harvested from cells in which abnormal accumulations of free fatty acids have been demonstrated.
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Ultrastructural and biochemical alterations were studied in the brainstem reticular formation of animals in which transient coma had been induced by controlled blows to the head. After a period of 7-10 days, animals that did not show obvious injury were artificially respired and sacrificed by perfusion with buffered formalin and glutaraldehyde. Histochemistry and light microscopy revealed chromatolysis of 10-15% of the neurons of pertinent segments of the nucleus giganto cellularis. There was much PAS-positive, diastase-sensitive material in the associated neuropil. Electron miscroscopy of the region confirmed the polysaccharide accumulation in dendrites, presynaptic boutons and preterminal axons. Similar material was found in some astrocytes. A longitudinal microchemical investigation with suitable controls of glycogen concentration in the brainstem demonstrated peak values at 5-7 days after concussion. No significant change in phosphorylase activity was demonstrated. The significance of glycogen accumulation in postconcussive injury and possible mechanisms for its accumulation in relation to changes in electrolyte balance and alterations in Kreb's cycle intermediates are discussed.
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1. A study of the mode and mechanism of Cu(2+)-induced mitochondrial swelling was carried out. 2. Mitochondrial swelling curves (E(520) turbidity changes) were obtained as a function of [Cu(2+)], pH, temperature and mitochondrial protein concentration. ED(50) was approx. 70mmumoles of Cu(2+). Calculation of the activation energy from the Arrhenius equation gave a value of 22900cal./mole per degree with Q(10) 4.02. 3. No lipid peroxides were formed during swelling. 4. Changes in oxygen consumption (Clark-type electrode) were dependent on the substrate used, but revealed no increased uptake in presence of Cu(2+). 5. Cu(2+)-induced swelling was inhibited by EDTA, 8-hydroxyquinoline, cyanide, citrate, bovine serum albumin, ATP, glutamate, GSH, dithiothreitol and sucrose. Azide, Amytal, antimycin A and oligomycin had no significant effect. Potentiation of swelling was seen with ascorbate, 2,4-dinitrophenol and succinate. 6. The occurrence of different types of mitochondrial swelling and the suggestion that Cu(2+)-induced swelling is mediated through a stoicheiometric interaction with a thiol-containing membrane receptor are discussed.