Biomedical subjects
Publications and source records attributed to P Lesker.
A comparison of the nuclei pulposi of 4 diabetic and 2 nondiabetic subjects disclosed a statistically significant decrease in hexosamine, a statistically significant increase of hydroxyproline, and significantly increased activities of four enzymes involved in the metabolism of carbohydrates. The results are considered preliminary in view of the small size of the sample.
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The articular cartilage of normal rats, of rats made diabetic with streptozotocin, and of rats made diabetic with streptozotocin and subsequently transplanted with isologous pancreatic islets was examined for the activities of enzymes engaged in the synthesis and degradation of glycosaminoglycans (mucopolysaccharides). The activities assayed were those of the degrading enzymes B-glucuronidase, B-acetyglucosaminidase, B-acetylgalactosaminidase, B-galactosidase, and those active in synthesis: uridine diphosphate dehydrogenase, glucose-6-phosphate dehyrogenase, and phosphofructokinase. In the diabetic animals all enzyme activities were increased, thos of the degrading enzymes more than those of the others. Implantation of pancreatic islets reversed the changes produced by diabetes, enzyme activities returning to near-normal levels.
Articular chondrocytes of achondroplastic mice (cn/cn) resemble ultrastructurally those of their non-achondroplastic siblings (Cn/Cn or Cn/cn), except for premature deposition of glycogen and a tendency to undergo regression. The latter may be slight or extreme. The ultimate cause of the vulnerability of the chondrocytes and the cause of the heterogeneity of the reaction could not be determined with the method employed. Nevertheless, increased vulnerability accounts for cell death under conditions which are usually not injurious, and which may be either physiologic or altered by endogenous or exogenous factors.
Skeletal development of achondroplastic (cn/cn) mice, aged 2 to 7 weeks, was investigated and compared with that of equally old non-achondroplastic sibs. Differences in body weight and dry weight of femora, tibiae, humeri, and unlae, and in the length of tibiae, unlae, and humeri became more marked with advancing age. Of the biochemical assays carried out, only those for sialic acid and hydroxyproline disclosed significant differences between dwarfs and non-dwarfs, all dwarfs having higher levels of hydroxyproline, and most of them having higher sialic acid levels than the non-dwarfs. Histologically, no distinction could be made between growth zones of non-dwarfs, of cn/+, or +/+ genotype. Among the dwarfs, two groups differing as to the severity of the skeletal abnormality could be distinguished. The differences between dwarfs were most marked in the growth zones of tibiae and femora, less conspicuous in those of vertebrae and least pronounced at the chondro-osseous junction of the ribs. The cause or causes of the histologic heterogeneity remain unknown.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The immediate effects of surgical dissection on regional bone blood flow were studied using the hydrogen washout technique and the results were compared in mature and immature rabbits. Epiphyseal circulation in young animals was eliminated by stripping the epiphyseal periosteum, and even in mature rabbits epiphyseal blood flow was markedly reduced by periosteal stripping. This suggests that after skeletal maturity blood supply crossing from the metaphysis into the epiphysis is limited. The blood flow rate was not altered by wide reaming of the epiphyseal center in either young or old animals. The rates of bone blood flow in the metaphysis and diaphysis were not altered by separate periosteal stripping or medullary reaming in either age group. Combined reaming and stripping eliminated blood flow in the diaphyseal cortical bone, but in the metaphysis fairly rapid blood flow remained even after reaming and periosteal stripping were done. These findings suggest that arterial supply and venous drainage traverse both endosteal and periosteal surfaces, and either system is capable of sustaining adequate bone tissue circulation.