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Biomedical subjects

S D Hanna

Publications and source records attributed to S D Hanna.

7 recordsLinked to original sources
PubMed1996

Antemortem diagnosis of human rabies.

Human rabies is a rare but fatal disease. In the United States, the majority of people infected with rabies contract the disease by being bitten by a wild animal, most commonly bats. Because rabies is so rarely seen, it is often not diagnosed until after death, at which time exposed health care workers will require rabies prophylaxis. We describe a case for which the diagnosis was made before death. The prompt consideration of this diagnosis allowed early isolation of the patient and prevented unnecessary risk to health care workers.

Adult↗
PubMed1979

Highly purified basal lateral plasma membranes from rat duodenum. Physical criteria for purity.

Preparations of intestinal epithelial cell basal lateral plasma membranes were analyzed with free flow electrophoresis and density perturbation with digitonin. The initial basal lateral membrane preparations were obtained by equilibrium density gradient centrifugation after two different schemes of homogenization and differential sedimentation (A.K. Mircheff, C.H. van Os, and E.M. Wright. 1978. Membr. Biochem. 1:177, and A.K. Mircheff, S.D. Hanna, M.W. Walling, and E.M. Wright. 1979. Prep. Biochem. 9:33. In these preparations, Na,K-ATPase, a marker for the basal lateral mambrane, was purified 16- to 18-fold over the initial homogenate. The preparations were also enriched in NADPH-cytochrome c reductase, alkaline phosphatase, acid phosphatase, and galactosyltransferase. Both free-flow electrophoresis, which separates on the basis of surface charge, and density perturbation with digitonin, which depends on a specific interaction of digitonin with cholesterol-rich membranes, resolved the preparation into three populations of particles. The major population, which represented basal lateral membranes purified 20- to 32-fold with respect to the initial homogenate, contained Na,K-ATPase, alkaline phosphatase, adenylate cyclase, and acid phosphatase. A second population was defined by its content of NADPH-cytochrome c reductase, and the third was defined by its content of galactosyltransferase. Guanylate cyclase appeared to be partitioned between the Na,K-ATPase-rich and NADPH-cytochrome c reductase-rich populations. Galactosyltransferase is also present in fractions which contain the Na,K-ATPase-rich membranes, but the present data cannot exclude the possibility of spillover by the adjacent, galactosyltransferase-rich population. This work emphasizes the importance of multiple, physical criteria for purity in the isolation of subcellular components.

Animals↗
PubMed1979

Alkaline phosphatase of basal lateral and brush border plasma membranes from intestinal epithelium.

The alkaline phosphatase present on isolated brush border and basal lateral membranes of rat duodenal epithelium were examined by means of a variety of biochemical assays and physical methods. The two alkaline phosphatases have similar pH optima of 9.6--9.8, similar substrate km's for p-nitrophenyl phosphate (PNPP) of 71 micromolar, similar responses to the inhibitors 2-mercaptoethanol, theophylline, phenylalanine, and ethylenediaminetetraacetic acid (EDTA), similar sensitivities to calcium, magnesium, zinc, sodium, and potassium, and similar insensitivities to digestion with trypsin of papain. The two enzymes also exhibit similar molecular weights on SDS-polyacrylamide gels in the range 124,000--150,000, and both enzymes show an Rf value of 0.092 on Triton X-100 polyacrylamide gels, indicating similar intrinsic charges. The Vmax of the brush border enzyme is ten times greater than that of the basal lateral enzyme, 140 mumoles/mg-h as opposed to 14 mumoles/mg-h. The differences in Vmax are a reflection of the known distribution of alkaline phosphatase in rat duodenum, there being more alkaline phosphatase activity present on the brush border than on the basal lateral surface. One other major difference was observed between the two enzymes, the stimulation of the basal lateral and not the brush border alkaline phosphatase by SDS, Triton X-100, or cholate. We conclude that the enzymes are very similar to one another and probably perform similar membrane functions.

Alkaline Phosphatase↗
PubMed1979

Large scale, analytical method for isolating basal lateral plasma membranes from rat duodenum.

A procedure is described for obtaining large amounts of basal lateral plasma membranes from the rat duodenal epithelium. The yield is approximately 50%, and the purification factor is 18; preparations from 25 rats routinely contain 100 mg of protein. The procedure depends on mild homogenization with a nitrogen cavitation bomb, followed by removal of brush borders by sedimentation in a weak centrifugal field. Basal lateral membranes in the resulting supernatant are partially purified by differential centrifugation in a medium which approximates their equilibrium density, and then further purified by equilibrium density gradient centrifugation in a high capacity zonal rotor. Brush border membranes may be isolated from the 450 x g pellet. Since both brush border and basal lateral membranes may be isolated from the same homogenate, this preparative procedure is suitable for such analytical purposes as determinations of distribution of enzyme activities between the two surfaces of the epithelium. The large scale of the isolation procedure makes it an appropriate starting point for purification of specific basal lateral membrane components.

Animals↗
PubMed1978

Comparison of the (Ca2+ + Mg2+)-ATPase proteins from normal and dystrophic chicken sarcoplasmic reticulum.

The involvement of membrane protein in dystrophic chicken fragmented sarcoplasmic reticulum alterations has been examined. A purified preparation of the (Ca2+ + Mg2+)-ATPase protein from dystrophic fragmented sarcoplasmic reticulum was found to have a reduced calcium-sensitive ATPase activity and phosphoenzyme level, in agreement with alterations found in dystrophic chicken fragmented sarcoplasmic reticulum. An amino acid analysis of the ATPase preparations showed no difference in the normal and dystrophic (Ca2+ + Mg2+)-ATPase. The (Ca2+ + Mg2+)-ATPase was investigated further by isoelectric focusing and proteolytic digestion of the fragmented sarcoplasmic reticulum. Neither of these methods indicated any alteration in the composition of the dystrophic (Ca2+ + Mg2+)-ATPase. We have concluded that the alterations observed in dystrophic fragmented sarcoplasmic reticulum are not due to increased amounts of non-(Ca2+ + Mg2+)-ATPase protein, and that the normal and dystrophic (Ca2+ + Mg2+)-ATPase protein are not detectably different.

Adenosine Triphosphatases↗
PubMed1977

Effect of methotrexate and 5-fluorodeoxyuridine on ribonucleotide reductase activity in mammalian cells.

A number of studies in bacteria have indicated that deoxythymidine 5'-triphosphate may be a repressor or corepressor of ribonucleotide reductase. For determination of whether a similar regulating mechanism exists in mammalian cells, HeLa cells and partially hepatectomized rats were treated with either methotrexate, 5-fluorouracil, or 5-fluorodeoxyuridine in order to block thymidylate synthesis and consequently lower the intracellular pools of deoxythymidine 5'-triphosphate. In HeLa cells there was a significant (360 to 400 percent) increase in reductase activity in both the methotrexate and 5-fluorodeoxyuridine-treated cells. The administration of methotrexate to partially hepatectomized rats resulted in a 2.7-fold enhancement of the hepatectomy-induced increase in reductase activity, and the 5-fluorouracil treatment yielded a 60 percent increment in the increase of ribonucleotide reductase activity after partial hepatectomy. Cycloheximide prevented the increase in reductase activity after the exposure of HeLa cells to methotrexate and 5-fluorodeoxyuridine, indicating that the stimulation of ribonucleotide reductase activity was the result of enhancement of de novo enzyme synthesis rather than of enzyme activation. The data support the thesis that deoxythymidine 5'-triphosphate or a thymidylate metabolite may be involved in the regulation of ribonucleotide reductase levels in mammalian cells.

Animals↗