Biomedical subjects
Publications and source records attributed to D M Young.
This study revealed that the lesions in platelets from cattle with the Chediak-Higashi syndrome (CHS) are not morphologically analogousto those present in the other granule-containing cells in cattle and other species with CHS. There was no evidence of enlargement of the lysosomal granules in bovine CHS platelets...
Long term, low dose administration of adriamycin (ADR) to young growing rabbits resulted in significant alterations in bone structure and chemistry. Morphologic changes were most pronounced at epiphyseal and metaphyseal areas of long bones. Epiphyseal cartilage plates were thin and there was derangement of growth zones. Areas of primary and secondary spongiosa were deficient in trabeculae, osteoblasts and osteoclasts. Analysis of femora, humeri and lumbar vertebrae from ADR-treated rabbits revealed increased water and fat content and significant decreases in bone density compared to age-matched controls. Cortices of long bones were roentgenographically thin and contained large irregular spaces evident microscopically. Evaluation of bone ash from ADR treated rabbits revealed significant increases in the percentage of calcium and phosphorus, although Ca/P ratios were not different from controls. Results of in vitro studies indicate that ADR binds readily to nondemineralized, but not demineralized, fresh cortical bone powder. The findings of decreased bone density, histopathologic alterations, and a paucity of osteogenic cells in ADR treated rabbits are interpreted as retardation of bone maturation. It is suggested that ADR affects adversely both the organic and inorganic fractions of bone. Due to its unique characteristics of cytostatic action, binding to metal cations and orange-red fluorescence, ADR is a novel chemical agent that may be useful in experimental bone studies.
Costal and auricular cartilage obtained from mutant rabbits exhibiting lysozyme deficiency has been found to be identical to similar tissue from control animals in a variety of biochemical parameters. These data seriously question the putative role of lysozyme as a structural component of cartilage.
After one dose of adriamycin, a subacute cardiomyopathy was observed in the mouse by both light and electron microscopy. The microscopic alterations were characterized by single-cell necrosis and mitochondrial degeneration. These lesions were similar to those seen in man and shortly preceded fatal toxicity.
Rabbits receiving adriamycin (ADR) on a chronic schedule developed significant histopathologic, ultrastructural and tissue electrolyte alterations of the ventricular myocardium. Rabbits that developed clinicopathologic evidence of cardiomyopathy with ADR had histologic lesions of the myocardium, including perivascular fibrosis, interstitial fibrosis and edema and myocytolysis. Ultrastructurally, large vacuoles resembling distended sarcoplasmic reticulum displaced the contractile elements and mitochondria, which were diminished in number within affected myocytes. Frequently, mitochondria appeared as electron-dense structures surrounded by layers of membranes resembling myelin figures. In addition, rabbits with cardiomyopathy had marked elevations in ventricular Ca, Na and H(2)O concentrations. Serum electrolytes were not significantly elevated, but lactic dehydrogenase (LDH) and creatine phosphokinase (CPK) were significantly increased, indicative of a cardiomyopathy. Rabbits receiving ADR but not developing clinicopathologic evidence of heart failure also had significant elevations in ventricular Ca, Na and H(2)O. Rabbits with no cardiomyopathy had no increases either in serum electrolyte concentrations or CPK and LDH levels. These studies indicate that marked increases in ventricular tissue Ca precede and accompany morphologic evidence of chronic myocardial degeneration and may be instrumental in the development of the ADR-induced cardiomyopathy.
A genetic disorder of rabbits consisting of a deficiency of the enzyme lysozyme is characterized. The condition appears to be inherited as an autosomal recessive trait. Most of the tissues of lysozyme-deficient rabbits including bone marrow, liver, lung. spleen and bone had levels of lysozyme which were 1% or less of the levels in the corresponding tissues of normal rabbits when measured with the lysoplate method. Levels of lysozyme in the kidney and serum were 6% of controls, but the thymus of the lysozyme-deficient rabbits had normal levels of the enzyme. All leukocytes of the lysozyme-deficient rabbits were negative for lysozyme when examined by a histobacterial technic. No morphologic lesions could be detected in any of the tissues of the lysozyme-deficient rabbits. Although several species of animals have been reported to be lysozyme deficient, this appears to be the first report of lysozyme deficiency occurring as a mutant condition. It is suggested that these mutant rabbits may be useful as a resource for experiments designed to delineate the biologic role of lysozyme.
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