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D F Wallach

Publications and source records attributed to D F Wallach.

At least 109 records · Page 6Linked to original sources
PubMed1975

Raman and resonance-Raman scattering by erythrocyte ghosts.

1. We present the laser-Raman spectra of human erythrocyte ghosts, isolated by standard conditions and compare these with the spectra of lecithin liposomes and fat-free serum albumin. 2. The hydrocarbon stretching modes of membrane lipids are temperature sensitive and may serve as a index of hydrocarbon chain motion. 3. The Amide I and Amide III bands of ghosts in H-2O and 2-H-2O, indicate a mixture of alpha-helical and unordered conformation, but do not allow a quantitative estimate of secondary structure. 4. Strong, scattering bands at 1530 and 1165 cm-1 are attributable to conjugated double bond systems, probably of membrane-associated carotenoids. Their high intensity is due to resonance enhancement.

Animals↗
PubMed1975

Concanavalin A-reactive protein of rabbit thymocyte plasma membranes: analysis by crossed immune electrophoresis and sodium dodecylsulfate/polyacrylamide gel electrophoresis.

1. Thymocyte plasma membrane extracts, prepared with the non-ionic detergent Triton X-100, show 10 major protein components upon sodium dodecysulfate/polyacrylamide gel electrophoresis and at least 11 immunologic components upon crossed immune electrophoresis. 2. Concanavalin A reactive membrane proteins have been identified using crossed immune electrophoresis with receptor-ligand interaction. 3. These proteins are absorbed from Triton X-100-solubilized membranes onto immobilized concanavalin A. They are eluted in stepwise fashion, using increasing concentrations of alpha-methyl-d-glucoside, between 0.0004 M and 0.1 M. The predominant proteins eluted in each step are components with high electrophoretic mobility in crossed immune electrophoresis and are identical with a glycosylated component in sodium dodecysulfate/polyacrylamide gel electrophoresis with molecular weight of 55 000. 4. This component forms multimers in the presence of Triton X-100 which are not totally dissociated in sodium dodecylsulfate. 5. Neuramidase treatment followed by crossed immune electrophoresis of total plasma membrane isolates, as well as the purified glycoprotein fraction, indicates that the concanavalin A-reactive proteins are sialoglycoproteins. 6. Sodium dodecylsulfate component 5.1 comprises at least two different populations of glycoproteins (6 and 9) in crossed immune electrophoresis, one of which exclusively exhibits heterogenous carbohydrate antigenic sites (component 9). 7. Present data, taken together with previously published experiments, indicate that concanavalin A binding to intact thymocytes induces an increased turnover and release of the receptor protein(s).

Animals↗
PubMed1975

Evidence for constrained lipid mobility in the erythrocyte ghost. A spin label study.

Our data show that the ESR spectrum of 5-nitroxide stearate bound to erythrocyte membranes varies with the amount of label bound and suggest that, at high binding, a significant proportion of label molecules lie within approximately equal to 15-10--8 cm; this gives rise to spin-exchange (ambient temperature) and dipole-dipole interactions. We find that these spectral manifestations due to label clustering can be abolished by reduction of pH and the conjoint action of lysolecithin and trypsin, although both perturbations increase 5-nitroxide stearate binding. Both perturbations are known to mobilize intramembranous particles by modifying or extracting some membrane proteins. We accordingly suggest that the lipids and proteins of erythrocyte membranes exist in a relatively fixed mosaic, and that the mobility of both components is restricted by some membrane-associated protein framework.

Cell Membrane↗
PubMed1975

Visualization of surface topology of human lymphoid cells by scanning electron microscopy.

We have studied the surface characteristics of human lymphoid cells with the scanning electron microscope (SEM). We obtained thymic cells by mincing thymus and isolating peripheral blood lymphocytes from normal donors as well as patients with acute and chronic lymphocytic leukemia (ALL and CLL). Prior to SEM, we purified the lymphocytes in isoosmotic Ficoll-Hypaque gradients. In addition, we examined several lymphoid cell lines in permanent culture derived from normal persons, patients with infectious mononucleosis, as well as from patients with ALL. The surfaces of most thymic cells appear smooth with only a few short microvilli. A small number of thymic cells, on the other hand, are found to exhibit many more microvilli of uniform shape and length. We could further identify lymphocytes from normal donors as T- and B-types according to their rosetting spontaneously with sheep red blood cells (SRBC) resemble thymic cells in their surface topology. However, B-cells rosetting with amboceptor--and complement--treated SRBC show greater number of microvilli. The surface morphology of lymphocytes from leukemic patients appears more or less characteristic of the disease type. In contrast, the surfaces of cultured lymphoid cells show a diversified surface topology, often with large smooth areas, very long and very short microcilli, which may often cluster in groups. These data bear directly upon techniques of plasma membrane fractionation and we suspect that the topology differences correlate with their differentiation patterns.

B-Lymphocytes↗
PubMed1975

Amino acid and sugar transport incells permissively infected with simian virus 40.

Transport of alpha-aminoisobutyric acid and 2-deoxy-D-glucose in African green monkey kidney cells was measured 8 to 100 hr following permissive simian virus 40 infection. No differences in transport were detected during the time-period studies, and no significant differences were seen between the apparent Michaelis-Menten constants of normal and virally infected cells. The absence of transport enhancement in permissive simian virus 40 infection suggests that the augmented transport of viral-transformed cell lines devolves upon altered host genome function.

Aminobutyrates↗
PubMed1974

Surface modification of T-lymphocytes observed during rosetting.

Scanning electron microscopy has been used to characterize alterations of lymphocyte surface topology that occur on contact with erythrocytes during the rosetting reaction. Molt-4 cells, a line of leukemic human lymphocytes, defined as T-cells through their ability to form rosettes with sheep erythrocytes, were used for this. Unreacted Molt-4 cells exhibit surfaces that are virtually smooth and carry few microvilli. In contrast, Molt-4 cells in rosettes display a time-dependent modification of surface topology, characterized by the emergence of numerous, long microvilli, particularly in areas of red cell contact.

Animals↗