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Biomedical subjects

S Smith

Publications and source records attributed to S Smith.

At least 973 records · Page 54Linked to original sources
PubMed1980

Expression of H-Y antigen on preimplantation mouse embryos.

The expression of H-Y antigen on preimplantation mouse embryos has been studied by complement dependent cytotoxicity. Embryos at the 8-cell stage were exposed to anti-H-Y and complement and then scored for cell death. Overall, half of the treated embryos were killed, retarded, or contained dead cells. Of those embryos which were not affected by anti-H-Y, 92% were female. In control experiments, neither normal serum plus complement nor complement alone had any specific effect on male embryos. It is concluded, therefore, that the H-Y antigen is present on preimplantation mouse embryos.

Animals↗
PubMed1980

Mechanism of chain length determination in biosynthesis of milk fatty acids.

Fatty acid synthetases isolated from all mammalian tissues synthesize predominately palmitic acid. However, in vivo the mammary gland fatty acid synthetases of some species are responsible for the synthesis of medium chain fatty acids. The objective of this presentation is to outline the mechanism which regulates the product specificity of fatty acid synthetases in general and to illustrate how this control is modified in the mammary gland. Fatty acid synthetases isolated from mammalian tissues are composed of two similar, probably identical, polypeptides, each carrying as many as seven enzyme components. Thioesterase I, the component which functions to terminate growth of acyl chains on the multienzyme, is located at one terminus of each polyfunctional polypeptide and can be detached by limited proteolysis with trypsin. By studying separately the kinetics of chain elongation by the core of the trypsinized complex and of chain termination by the isolated thioesterase I component, it has been possible to establish that the specificities of the elongation and termination reactions account for the synthesis of predominantly the carbon-16 fatty acid by purified fatty acid synthetases. Mammary glands of some species contain an additonal enzyme, thioesterase II, which can modify the product specificity of fatty acid synthetase by hydrolyzing medium chain acyl moieties from thioester linkage to the 4'phosphopantetheine of the multienzyme. At all stages of development of rat mammary gland, the amount of theoesterase II present correlates well with the proportion of medium chain fatty acids synthesized by the gland. This mammary gland-specific thioesterase appears responsible for the ability of this tissue to synthesize medium chain fatty acids characteristic of milk fat.

Animals↗
PubMed1980

Membrane alterations during cataract development in the Nakano mouse lens.

The anterior cortical fiber cells of the 12-day-old Nakano mouse lens revealed an extremely large number of gap junctions, the appearance of which was identical to those of the normal lens. Although the number of gap junctions of the cells in the same area at 29 days was comparable to that seen at 12 days, the size of each junction became smaller with cataract formation. The junctions were almost absent in the anterior cortical cells in 7-month-old Nakano mice. Biochemical analysis revealed that the 26,000 MW polypeptide closely associated with the cell membrane was lower in amount in the membrane preparation of the 29-day Nakano mouse lens than in the 12-day lenses. With the membrane fractions of lenses from 90-day Nakano mice, the absence of a major 26,000 NW polypeptide component correlates with the decrease in gap junction structures. The alternations in the gap junctions and membrane associated polypeptides of the Nakano lens may be linked with the steps leading to cataract development.

Aging↗
PubMed1980

Systemic anti-inflammatory effect associated with enteric trichinellosis in the rat.

The hypothesis tested was that enteric parasites that induce local inflammation in their host suppress inflammatory reactions at distant sites. A technique was developed to demonstrate, quantitatively, such an anti-inflammatory component. The systemic antiphlogistic effect produced by the intestinal stages of Trichinella spiralis was studied and compared with that caused by dexamethasone, a synthetic adrenocortical steroid. Inflammation was measured (dry weight, protein content, myeloperoxidase activity) as the amount of granulation tissue accumulated around a sterile cotton string implanted for 1 wk under the abdominal skin of rats. Based on this assay, T. spiralis infection had a systemic anti-inflammatory effect on the host which was directly dose related. Steroid treatment also had a dose-dependent suppressive effect on granuloma formation. The maximum dose (56 X 10(3) larvae/kg body weight) of T. spiralis used, had suppressive activity equivalent to 1.0 mg/kg body weight of steroid.

Animals↗
PubMed1979

Lymphatic abnormalities in Noonan syndrome: A case report.

Lymphatic abnormalities are not generally recognized as part of the Noonan syndrome. A child with this condition in whom unique and widespread lymphatic abnormalities were demonstrated by lymphography is described. Both T and B lymphocytes were detected in chylous fluid drained from the thorax. In addition, the child was found to have a protein-losing enteropathy and cardiovascular defects. The clinical spectrum of the Noonan syndrome may include animalies of the lymphatic system.

Cardiac Catheterization↗
PubMed1979

An analysis of the polypeptide composition of bovine heart mitochondrial NADH-ubiquinone oxidoreductase by two-dimensional polyacrylamide-gel electrophoresis.

Purified preparations of Complex I (NADH-ubiquinone oxidoreductase) from bovine heart mitochondria may be resolved into 26 polypeptides by two-dimensional analysis combining isoelectric focusing and polyacrylamide-gel electrophoresis in sodium dodecyl sulphate. Similar analyses of the fragments obtained from chaotropic resolution of the enzyme show that each of these fragments contains a distinct and non-overlapping set of polypeptides. Evidence that the polypeptides seen in the intact enzyme are true constituents comes from analyses of immunoprecipitates obtained by allowing Complex I or solubilized submitochondrial particles to react with antisera directed against the whole enzyme and a subfragment of the enzyme.

Animals↗