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Biomedical subjects

D F Wallach

Publications and source records attributed to D F Wallach.

At least 19 recordsLinked to original sources
PubMed1979

Two Plasmodium knowlesi-specific antigens on the surface of schizont-infected Rhesus monkey erythrocytes induce antibody production in immune hosts.

Purified schizonts (6--10 nuclei) and membranes of schizont-infected erythrocytes from the Malaysian and Philippine strain of Plasmodium knowlesi are analyzed immunochemically using immunoglobulin of rhesus monkey hyperimmune sera against schizonts and of sera from naturally immune monkeys. The anti-schizont Ig identifies less than 20 immune components in Triton X-100-solubilized schizonts and membranes of infected cells. Of these antigens, 9 (component 1, 3, 4, 5, 6, 10, 11, 18, and 20) are common to parasites and membranes of infected erythrocytes, and 12 (2A,B, 6, 8, 9, 12, 13p, 14, 16A,B, 19 A,Bp, 21, 22p, and 23) are predominantly found in the parasite; 4 components (13i, 19A,Bi, 22A, B, and 24) are unique to the membrane of infected erythrocytes. Only three parasite-specific components (1, 13, and 19) are exposed on the surface of parasitized erythrocytes as revealed by both lactoperoxidase-catalyzed radioiodination and extensive absorption of anti-schizont Ig using intact infected erythrocytes. Two plasmodium-specific antigens (1 and 13) on the surface of infected erythrocytes are recognized by sera of rhesus monkeys rendered naturally immune against P. knowlesi infections and, therefore, represent antigens in vivo. Analyses of schizonts and membranes of parasitized erythrocytes of the two different strains of P. knowlesi yields only some minor quantitative, but no qualitative differences when analyzed with both types of antisera. Importantly, components 1 and 13 appear identical in both strains.

Animals↗
PubMed1979

Fractionation of Plasmodium knowlesi-induced antigens of rhesus monkey erythrocyte membranes.

In order to characterize parasite-induced host cell membrane antigens, the plasma membranes of Plasmodium knowlesi-infected rhesus erythrocytes have been compared with those of normal red cells and purified schizonts by immunochemical and biochemical techniques. Host cell membranes and schizonts were separated by differential centrifugation following nitrogen decompression. Isolated schizonts were further fractionated into several subcellular compartments. Crossed-immune electrophoresis, against monkey anti-schizont serum, of Triton X-100-solubilized material identified 7 P. knowlesi-specific antigens, of which 4 could be detected only in the host cell membranes. These membranes also contained 3 proteins, with relative molecular masses of 55 000, 65 000 and 90 000 and isoelectric points at pH 4.5, 4.5 and 5.2, respectively, which are lacking in normal membranes. Pulse-chase experiments with ((14)C)-glucosamine showed that these parasite-induced host cell membrane components are glycoproteins.

Animals↗
PubMed1978

Plasmodium knowlesi-induced antigens in membranes of parasitized rhesus monkey erythrocytes.

Highly purified Plasmodium knowlesi schizonts were used to produce a hyperimmune anti-parasite serum in a rhesus monkey. Proteins of membranes from normal and P. knowlesi-infected erythrocytes, as well as purified schizonts, were solubilized in 1% Triton X-100 and analyzed by bidimensional electrophoretic techniques. Of seven parasite-specific antigens identified in membranes of parasitized erythrocytes by crossed immune electrophoresis against monkey anti-parasite serum, only three could be detected in the purified schizonts. Bidimensional focusing-dodecyl sulfate/polyacrylamide gel electrophoresis of membranes from parasitized cells revealed three proteins, in the 55,000-90,000 molecular weight region, with isoelectric points between pH 4.5 and pH 5.2, that could not be detected in normal membranes or purified schizonts. Membranes of normal erythrocytes and uninfected erythrocytes that had been incubated with sera from monkeys with 25-50% parasitemia did not react with the monkey anti-parasite serum.

Animals↗
PubMed1978

Effect of transmembrane ion gradients on Raman spectra of sealed, hemoglobin-free erythrocyte membrane vesicles.

Sealed hemoglobin-free erythrocyte vesicles have been isolated. Imposition of transmembrane cation gradients increases the intensity of Raman scattering in the CH3-stretching region as observed with unsealed ghosts at temperatures greater than 38 degrees C and pH less than 7.0 [Verma, S. P. & Wallach, D. F. H. (1976) Proc. Natl. Acad. Sci. USA 73, 3358--3561]. Modifications in the amide I and amide III frequencies consistent with increased helicity of membrane proteins are observed upon imposition of a cation gradient. Spectrin-free vesicles also demonstrate cation gradient-sensitive intensity changes in the CH3-stretching region. However, no evidence for cation gradient-related protein conformation changes is found with these vesicles. The transmembrane potential of these vesicles has been altered by variations in anion composition and the electrogenic activity of Na+,K+-ATPase. The membrane potential was monitored by cyanine dye fluorescence. Imposition of a membrane potential (negative inside) also increased the intensity of Raman scattering in the CH3-stretching region. These results suggest that a transmembrane potential (negative inside) and/or cation gradient can energize membranes by compression of the apolar region and transfer of protein methyl residues into polar regions.

Erythrocyte Membrane↗
PubMed1978

Modification of rat thymocyte membrane properties by hyperthermia and ionizing radiation.

Thymocytes are one the most widely used cell models for the study of radiation-induced interphase death. This cell-type was chosen for the study of hyperthermic and radiation effects on two membrane-related processes implicated in the interphase death of cells: Na+-dependent 2-aminoisobutyric acid (AIB) transport and cyclic 3'-5' adenosine monophsophate formation. The response of AIB transport to heat is dose-dependent, but the biphasic thermal response curve (AIB uptake versus time) differs fom the sigmoidal radiation response curve. Heating thymocytes for 20-30 min at 43 degrees C stimulates AIB uptake. Additional heating at 43 degrees C, however, markedly reduces AIB uptake. Despite the immediate stimulating effect of heat (30 min at 43 degrees C), the thymocyte has already developed irrepairable impairments, as demonstrated by the fractionated heating experiments. The heat-induced impairment of AIB uptake is mainly on the Na+-dependent component of neutral amino-acid transport, affecting primarily the maximal rate of uptake, i.e. Vmax. Additional evidence for heat-induced plasma membrane damage is the alteration in cAMP levels. Heating thymocytes for 30 min or longer at 43 degrees C causes a massive rise in cAMP level within the cell. This differs from thymocytes exposed to radiation where no rise in cAMP is observed.

Aminoisobutyric Acids↗
PubMed1978

Impairment of Na+-dependent amino acid transport in a cultured human T-cell line by hyperthermia and irradiation.

We have examined the effects of hyperthermia and radiation on the ability of a human T-leukemic lymphocyte line (Molt-4) to transport the Na+-dependent amino acid, 2-aminoisobutyrate (AIB). Heating Molt-4 at 43 degrees for 1 to 4 hr damages the ability of these cells to accumulate AIB. The damage to the transport system at 43 degrees impairs only the maximal rate of AIB uptake, i.e., Vmax. The thermal effect on AIB transport parallels the radiation effects observed for this system. Preliminary data indicate that heat and radiation may induce irreversible transitions in the tertiary or quaternary structure of a plasma membrane protein involved in regulating Na+-dependent amino acid transport. However, the mechanism by which heat and radiation damage this protein is different.

Aminoisobutyric Acids↗
PubMed1977

Periodate induced cross-linking of concanavalin A-reactive membrane proteins of rabbit thymocytes.

Purified plasma membranes of rabbit thymocytes are exposed to sodium periodate and galactose oxidase at conditions similar to those used to induce mitogenic transformation of lymphocytes. The membrane proteins are then fractionated by dodecyl sulfate poly-acrylamide gel electrophoresis. At concentrations of 0.005 M, Na IO4 cross-links 55,000 D and 110,000 D glycoproteins which are known to specifically bind concanavalin A. Galactose oxidase has a similar cross-linking effect, but, at the same time causes proteolytic degradation of membrane proteins. Our data indicate that oxidizing agents, like NaIO4 and galactose oxidase, can indeed cross-link receptors of the thymocyte plasma membrane as has often been proposed as a possible mechanism of their action.

Animals↗
PubMed1977

Simian virus 40-specific proteins in the membranes of simian virus 40-transformed hamster and mouse cells.

Membranes of simian virus 40-transformed hamster lymphocytes and phagocytes, as well as of transformed mouse fibroblasts, contain two classes of antigenic virus-specific protein. The isoelectric points of these proteins, as defined by isoelectric focusing/immune electrophoresis are at pH 4.5 and 4.7. The molecular weights of the pI 4.5 and pI 4.7 components, determined by isoelectric focusing/dodecyl sulfate polyacrylamide electrophoresis, lie near 58,000 and 90,000-110,000, respectively. The pI 4.5 and pI 4.7 proteins are tentatively identified with the surface (transplantation) and U antigens, respectively.

Animals↗
PubMed1977

Antigenic distinctions of glycoproteins in plasma and mitochondrial membranes of lymphoid cells neoplastically transformed by simian virus 40.

Highly purified plasma membranes from hamster lymphocytes transformed by simian virus 40 (GD 248) were compared with the membranes of normal cells by crossed immune electrophoresis, crossed-line immune electrophoresis, and bidimensional isoelectric focusing-immune electrophoresis. Antiserum raised by inoculation of guinea pigs with GD 248 membranes was used as serologic reagent, either directly or after absorption with membranes from normal cells. Bidimensional immune electrophoresis reveals the presence in the plasma membranes of GD 248 cells of at least three antigens not detectable in the membranes from the normal cell population. At least two of these are also present in the mitochondrial membranes of GD 248 cells, but none could be detected in membranes of embryonic fibroblasts. Bidimensional isoelectric focusing-immune electrophoresis indicates that the distinctive antigens of the GD 248 membranes are glycoproteins.

Animals↗
PubMed1977

Regulation of cholesterol biosynthesis by normal and leukemic (L2C) guinea pig lymphocytes.

The cholesterol production of guinea pig leukemic (L2C) lymphocytes preceeds at greater than 30 times the rate found in normal cells. Fatty acid biosynthesis is also enhanced in L2C cells. Exposure of L2C cells to cholesterol/lecithin liposomes does not depress their sterol biosynthesis, in contrast to the behavior of normal lymphocytes [Philippot, J.R., Cooper, A.G. & Wallach, D. F. H. (1975) Biochim. Biophys. Acta 406, 161-166]. However, 25-hydroxycholesterol, an inhibitor of hydroxymethylglutaryl-CoA reductase (NADPH) [mevalonate: NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34], the rate limiting enzyme in cholesterogenesis, and 25-hydroxycholecalciferol, a biologically potent form of vitamin D3, block sterol biosynthesis of both normal and L2C lymphocytes [Philippot, j.r., cooper, A.G. & Wallach, D.F.H. (1976) Biochem. Biophys. Res. Commun. 72, 1035-1041]. Moreover, both cell types exchange cholesterol equivalently with cholesterol/lecithin liposomes. The only difference in sterol biosynthesis observed between the two cell types is in the temperature response of the enzyme. Arrhenius plots of this enzyme activity exhibit a prominent discontinuity at about 24 degrees in the case of normal cells, but none in the case of L2C. The activation energies for L2C cells and normal cells, above the normal cell transition temperature, were not significantly different. All of the data suggest that the regulatory defect in L2C lymphocytes arises from a deficiency in these cells' internal membranes.

Androstanes↗
PubMed1977

Transformation by simian virus 40 induces virus-specific, related antigens in the surface membrane and nuclear envelope.

Nucleus- and mitochondrion-free membranes from hamster lymphocytes transformed by simian virus 40 (SV40), GD248 cells, cause guinea pigs to produce immune sera that reveal the presence in GD248 plasma membranes and mitochondria of two types of glycoprotein that are not detected in membranes of normal lymphocytes [Schmidt-Ullrich, R., Thompson, W. S. & Wallach, D. F. H. (1977) Proc. Natl. Acad. Sci. USA 74, 643-647]. Indirect immune fluorescence of living, SV40-transformed T19 hamster reticulum cells, Balb/c 3T3 mouse fibroblasts, and W18 VA2 human fibroblasts, using the antisera against GD248 membrane, at 4 degrees produced a distinct cell surface fluorescence; however, above 20 degrees , staining at the nuclear perimeter, the SV40 U-antigen reaction, becomes equally prominent. In SV40-transformed cells that had been fixed in cold acetone, as well as in purified GD248 nuclei, thermostable U-antigen staining is dramatic, but there is no reaction for nuclear T-antigen. Rabbit antisera against T19 cells gave immunofluorescence reactions equivalent to those obtained with the antisera against GD248 cells. Normal guinea pig or rabbit sera and cells that had not been transformed by SV40 gave no reaction. Our sera from tumor-bearing hamsters gave only nuclear T-antigen fluorescence. The results indicate the presence of related, SV40-specific antigens in the surface membranes, nuclear envelope, and possibly other intracellular organelles of SV40-transformed cells.

Antigens, Viral↗