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Biomedical subjects

P S Lin

Publications and source records attributed to P S Lin.

At least 109 records · Page 6Linked to original sources
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

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↗
PubMed1977

Evaluation of intracytoplasmic particles in histiocytes after endodontic therapy with a hydrophilic plastic.

The presence of granules within the cytoplasm of periapical tissue histiocytes had been observed in teeth which had a root canal overfilled with a hydrophilic plastic polymer. SEM examinations revealed these granules to be barium sulfate, which was added to the polymer for radiopacity. X-ray spectra revealed strong calcium peaks in bone adjacent to the histiocytes, which showed strong barium peaks. In addition, between the histiocytes and the bone a greater concentration of calcium was seen. Because the histiocytes and not the plastic polymer contained barium sulfate, the evidence for this material's biocompatibility is greatly enhanced.

Animals↗
PubMed1977

Prolongation of antibacterial activity of chlorhexidine adsorbed to teeth. Effect of sulfates.

The results suggest that the effectiveness of sulfates in prolonging the antibacterial activity of teeth treated with chlorhexidine gluconate is related to the acidity and concentration of the sulfate solutions. The acidity may contribute to the effectiveness by modifying the tooth surface for enhanced reaction with sulfate ions. It is suggested that during the priming process bonded crystals of calcium sulfate develop which become transformed by treatment with chlorhexidine gluconate to relatively insoluble chlorhexidine sulfate.

Acid Etching, Dental↗
PubMed1976

Altered surface topology and membrane functions of rat thymocytes eluted from nylon wool columns.

(1) Following incubation of thymocytes with nylon wool at 37 degrees C, the eluted cells showed an increase in the number of microvilli per cell and a concominant elongation of the microvilli (0.22 mum versus 1.15 mum. (2) Cyclic adenosine monophosphate (cylic AMP) levels were lowered by 30-50% in nylon wool-treated thymocytes. (3) Nylon wool-treated cells showed an impaired Na+-dependent amino acid transport system (2-aminoisobutyrate) whereas the Na+-independent amino acid transport system (1-aminocyclopentane-1-carboxylate) was unaffected.

Amino Acids↗
PubMed1976

The use of backscattered electrons for imaging purposes in a scanning electron microscope.

It is shown that the use of a very large detector for backscattered electrons can provide a signal comparable to that obtained in the secondary emission mode and that the resolution available is also comparable. A technique is described whereby the difference is taken between these two signals, and the use of this difference signal can significantly enhance surface details. It is believed that the use of such a signal should ultimately prove advantageous in increasing resolution.

Animals↗
PubMed1976

Sheep erythrocytes binding ability on a mouse renal adenocarcinoma cell line and its hybrid with human lymphocytes.

A mouse renal adenocarcinoma (Rag) cell line, not related to L cells, rosette with erythrocytes from sheep and mice. The Rag-cell rosettes are performed in suspension and on coverslips. Microscopically they rosette like human T cell. No virus-like particles thus far have been found between the rosetted cells. However, the sheep erythrocyte binding ability of Rag cells are very different as compared to human T cells. The former cannot be impaired by trypsin-EDTA treatment nor inhibited by rabbit anti-human thymocyte immunoglobulin, sodium azide or sodium iodoacetate. Two hybrid clones isolated between Rag-human lymphocytes show similar rosette characteristics as the Rag cells.

Adenocarcinoma↗
PubMed1975

Action of halothane on human erythrocytes. Mechanisms of cell lysis and production of sealed ghosts.

1. Suspension of human erythrocytes in halothane-saturated physiological media induces major cell deformation. 2. Release of halothane from erythrocyte suspensions after equilibrium with the anaesthetic produces complete hemolysis. 3. The membrane fragments isolated after halothane release are in the form of biconcave ghosts, impermeable to macromolecules (lactoperoxidase) and small molecules (ATP). 4. The protein composition of the membranes differs from that of ghosts produced by hypotonic lysis in the lack of components previously shown to be adsorbed at low ionic strength. 5. A hypothesis is presented explaining the action of halothane in terms of both its action on membranes and its capacity to modify water structure. 6. Halothane-induced hemolysis constitutes a simple method for the large-scale production of hemoglobin-depleted, sealed erythrocyte ghosts under physiological ionic conditions.

Adenosine Triphosphatases↗
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↗
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↗
PubMed1974

Focal erythrocyte membrane perturbations caused by nitroxide lipid analogues.

Three classes of lipoidal nitroxide spin probes reversibly perturb erythrocyte membranes at low concentrations (10(-10)-10(-5) M). This is manifest in (a) decreased osmotic fragility and (b) alterations of surface topology. At bulk phase nitroxide concentrations providing maximal osmotic stabilization, the erythrocytes exhibit a classic echinocyte morphology. At nitroxide concentrations very slightly higher than those yielding minimal osmotic fragility (10(-5)-10(-4) M), the cellus undergo a sphering reaction and lyse. The morphologic sequence seen in intact cells is not observed in erythrocyte ghosts. We suggest that the spin probes initially concentrate in focal domains, which expand into echinocytic protrusions primarily due to localized weakening of membrane cohesion. We propose that cell lysis involves an irreversible breakdown in membrane domain structure.

Cell Membrane↗
PubMed1973

Temperature-induced variations in the surface topology of cultured lymphocytes are revealed by scanning electron microscopy.

Temperature-induced variations in the surface morphology of cultured lymphocytes were evaluated by scanning electron microscopy. At 25-37 degrees the cells' surfaces are largely obscured by numerous undulating microvilli of various lengths but uniform diameter. Temperature changes alter the number of microvilli, their lengths, diameters, distribution, branching, and fusing. Typically, chilling to 0-4 degrees markedly reduces the number of microvilli and increases the diameter of the survivors in a reversible process. In contrast, heating the cells to about 45 degrees rapidly and irreversibly transforms the ordinarily smooth membrane surface into one with a "cobblestone" morphology. At the same time most microvilli disappear and the few that remain clump into a cap. The data suggest that the low-temperature effects reflect a change in the physical state of membrane lipids, while the high-temperature alterations represent thermotropic protein transitions.

Animals↗