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Biomedical subjects

F A Green

Publications and source records attributed to F A Green.

At least 73 records · Page 4Linked to original sources
PubMed1981

Hypertonic cryohemolysis and the cytoskeletal system.

Hypertonic cryohemolysis is defined as the lysis of erythrocytes in a hypertonic environment when the temperature is lowered from above 15-18 degrees C below that temperature. This has been found to be a general phenomenon (that is, whether the solute is charged or not), to exhibit interesting temperature characteristics and to be preventable by agents such as valinomycin which tend to dissipate the concentration gradient across the cell membrane. As yet, no clear information is available to translate this phenomenon to the molecular level and to relate it to current structure/function concepts in the erythrocyte membrane. In this study, data are presented which would indicate on the basis of two entirely separate methodologies that the spectrin-actin cytoskeletal framework is involved in this phenomenon. The first of these methodologies is based on radiation-induced ablation of cryohemolysis and indicates that an intact macromolecular complex of an order of 16000 000 daltons is required for cryohemolysis with hypertonic NaCl. The second methodology is based on selective cross-linking of spectrin and actin in the agent diamide, which resulted in concentration-dependent suppression of cryohemolysis. Polyacrylamide gel electrophoresis of the erythrocyte from diamide-treated cells showed intense protein aggregation with loss of spectrin-actin and bands 4.1, 4.2. We conclude that the spectrin-actin cytoskeletal system possibly including its interaction with phospholipids is the key to the phenomenon of hypertonic cryohemolysis.

Cold Temperature↗
PubMed1981

Glucose transport carrier of human erythrocytes. Radiation target size measurement based on flux inactivation.

Intact human erythrocytes frozen in the presence of cryoprotective reagents and irradiated with an electron beam retained their diffusion barrier to L-glucose. The carrier-mediated flux of D-glucose, on the other hand, was inactivated as a simple exponential function of the radiation dose. Classical target size analysis of this data yielded a molecular size of 185,000 daltons for the carrier. This represents the first measurement of the functional size of a transport protein based directly on flux inactivation.

Biological Transport, Active↗
PubMed1981

Assessment and interpretation of radiopharmaceutical joint imaging in an animal model of arthritis.

An animal model of arthritis in the rabbit was employed to assess the radioactivity contribution of joint tissues to externally monitored scintigram positivity. Bone contained the greatest total amount of radioactivity whether the imaging agent was technetium pertechnetate or pyrophosphate, although the greatest percent increase in the arthritis joints over control joints was seen in synovium. Mid-shaft bone in the same region as the arthritic joint also showed increased radioactivity compared with control.

Animals↗
PubMed1980

Prevalence of occult inflammatory bowel disease in ankylosing spondylitis.

Fifty-five patients with ankylosing spondylitis and 16 control patients matched for sex and age were examined for evidence of occult inflammatory bowel disease. In all patients evaluation included history and physical examination, barium enema, sigmoidoscopy, and rectal biopsy. The results of this study suggest that there is no increased prevalence of occult inflammatory bowel disease in patients with ankylosing spondylitis.

Adult↗
PubMed1980

alpha-Methyldopa and the erythrocyte membrane.

Alpha-methyldopa binds to human erythrocyte membrane proteins. A portion of this binding is readily dissociable in SDS but a significant amount is very tightly bound and does not come off even under rigorous conditions. The binding is increased under oxidizing conditions and very much inhibited in the presence of reducing agents as well as superoxide dismutase and catalase. Haemoglobin competes with membrane peptides for alpha-methyldopa binding. It is postulated that haemoglobin acts as a 'sink' for the drug in the intact cell and that the first step in the pathogenesis of Coombs positivity and haemolytic anaemia results from an alteration of a critical membrane peptide secondary to binding of the drug during normal membrane breakdown.

Binding, Competitive↗
PubMed1978

Hypertonic cryohemolysis: ionophore and pH effects.

Human erythrocytes suspended at 37 degrees C in hypertonic solution of either electrolytes or nonelectrolytes undergo hemolysis when the temperature is lowered toward 0 degrees C (Green, F.A., Jung, C.Y. 1977 J. Membrane Biol. 33:249). In the present studies this hypertonic cryohemolysis was profoundly affected by the pH of incubation, and was completely abolished at ph 5. In hypertonic NaCl, there was an apparent pH optimum at 6--6.5. In hypertonic sucrose, on the other hand, hemolysis increased progressively with increasing pH between 6 and 9. Amphotericin B inhibited hypertonic cryohemolysis in NaCl or KCl solution. No inhibiting effect of amphotericin B was observed when hypertonicity was due to sodium sulfate or sucrose. Valinomycin also inhibited hypertonic cryohemolysis in KCl, but did not affect the process in NaCl or sucrose solution. SITS (4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate) and phloretin interfered with this valinomycin effect, whereas phlorizin did not. These results indicate that dissipation of an osmotic gradient across membranes may be responsible for the inhibition of the hemolysis by these inophores. Iso-osmotic cell shrinkage induced by valinomycin in 150 mM NaCl solution did not result in cryohemolysis.

Amphotericin B↗
PubMed1977

Cold-induced hemolysis in a hypertonic milieu.

Suspension of human erythrocytes at 37 degrees C in an environment made hypertonic by increasing concentrations of sodium chloride and sucrose was followed by hemolysis when the temperature was lowered to 0 degrees C. Two distinct stages were involved in this hemolytic phenomenon, the first being incubation with hypertonic solute at some temperature above 20 degrees C with an increasing effect up to 45 degrees C, and the second stage consisting of lowering the temperature below 15 degrees C with increasing hemolysis down to 0 degrees C. The rate of cooling was not an important factor, but the presence of ions reduced the extent of cold-induced hemolysis in hypertonic sucrose. No significant release of membrane phospholipid and cholesterol accompanied this hemolysis. The solubilization of membrane protein components was investigated, with some differences appearing on sodium dodecyl sulfate polyacrylamide gel electrophoresis between hypertonic and isotonic supernatants. Spectrin could not be identified in solubilized form. Correlation of the temperatures of note in these studies with results from the literature on other biological effects of temperature-induced phase transitions in membrane lipids strongly points to the conclusion that such transitions are involved in the mechanism of cold-induced hypertonic hemolysis. It is postulated that the hypertonic milieu has resulted in membrane-protein alteration damage which prevents normal adaption to the new physical state of the membrane lipids during cooling.

Cold Temperature↗
PubMed1975

Reconstitution of Rh (D) antigen activity from human erythrocyte membranes solubilized by deoxycholate.

Proteins were selectively solubilized from human erythrocyte membranes with deoxycholate. After ultracentrifugation and preliminary fractionation procedures, the detergent was removed from the soluble membranes by Bio-Beads SM-2 and dialysis against 5 millimolar magnesium chloride. Reaggregation took place with the apparent formation of vesicles which showed serologically specific Rh antigen activity.

Cell Fractionation↗