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Biomedical subjects

J W Shands

Publications and source records attributed to J W Shands.

At least 55 records · Page 3Linked to original sources
PubMed1975

Capping of the lymphocyte C3 receptor and temperature-dependent loss of C3 rosettes.

The percentage of mouse spleen cells rosetted by bacteria-antibody-complement complexes (BAC) was found to be temperature dependent. Maximal rosetting was observed when BAC and spleen cells were incubated in ice (0.5 degrees C), whereas less rosetting resulted from 37 degrees C incubations. When rosetted cells were incubated at 37 degrees C, cap formation was found to occur, and indirect evidence suggested that the capped bacteria were subsequently shed from the lymphocyte surface. Neither capping nor shedding occurred at 0.5 degrees C, suggesting that these phenomena were responsible for the decreased percentage of rosetted cells found after incubation at 37 degrees C. An incidental observation indicated that a second factor potentially contributing to the loss of rosetted cells at 37 degrees C was the removal of BAC from the surface of cells by phagocytes.

Animals↗
PubMed1975

Endotoxin-stimulated spleen cells: characterization of the responding cells.

The percentage of endotoxin-stimulated lymphoblasts possessing C3 receptors (CR) decreases during a 72-hr period of in vitro cultivation. In studies reported here we attempted to determine whether the drop in the percentage of CR+ blast cells resulted from receptor loss by transformed cells or whether it resulted from the proliferation of additional blast cell types which lacked the CR. Using methods which permitted simultaneous detection of cytoplasmic IgM, the presence of the CR, and 3H-thymidine uptake we found that: a) LPS stimulation resulted in a progressive increase in the number of IgM+ blasts, b) these constituted approximately 30% of the total cell population at 72 hr after LPS stimulation, c) of the IgM+ blasts 72 to 84% were CR+ and 16 to 28% were CR- at 72 hr, d) from 48 to 72 hr there was no decrease in the percentage of IgM+ blasts possessing the CR, and e) an additional blast cell type was observed which incorporated 3H-thymidine but which was IgM- and lacked the CR. These cells constituted from 11 to 27% of total 3H-thymidine+ cells at 72 hr after LPS stimulation. We conclude that the decrease in the percentage of CR+ blasts in LPS-stimulated spleen cell cultures is not due to receptor loss from IgM+ blasts cells but apparently is partly due to the stimulation and proliferation of other cell type(s) which lack(s) the CR. This cell(s), although its functional identity is unknown, does not appear to be of thymic origin. The heterogeneity of the markers on LPS-stimulated blast cells suggests that a heterogeneous population of cells responds to LPS.

Animals↗
PubMed1974

In vitro and in vivo effects of endotoxin on mouse peritoneal cells.

The in vitro effect of endotoxin (LPS) on unfractionated mouse peritoneal cells and cells fractionated into glass adherent and nonadherent populations was studied. LPS caused blast transformation and deoxyribonucleic acid synthesis in the nonadherent, nonphagocytic cells. There was no evidence of a mitogenic effect on macrophages. Instead, a cytotoxic effect was noted. When incubated with unfractionated peritoneal cells, LPS was still cytotoxic for macrophages, but the mitogenic effect for nonadherent cells was decreased or ablated. The intraperitoneal administration of LPS to mice resulted in an acute inflammatory response with a transient depletion of mononuclear cells. There was no stimulation of division of macrophages. Data were obtained which indicated that local cell division is an important factor in the normal turnover of peritoneal macrophages.

Animals↗
PubMed1973

Differential morphology of mouse spleen cells stimulated in vitro by endotoxin, phytohemagglutinin, pokeweed mitogen and staphylococcal enterotoxin B.

The in vitro mitogenic effects of endotoxin (LPS), phytohemagglutinin (PHA), pokeweed mitogen (PWM) and staphylococcal enterotoxin B (SEB) on mouse spleen cells were studied by light and electron microscopy. By light microscopy, LPS was found to "transform" a culture largely composed of small lymphocytes into "large lymphocytes" which did not synthesize DNA and into blast cells which did synthesize DNA. The blast cells were morphologically similar to those transformed by PHA, PWM and SEB. By electron microscopy, a large percentage of the endotoxin-transformed cells developed extensive dilated rough ER. Their appearance was similar to that reported by others for cells stimulated by PWM, but in our hands the development of rough ER was more conspicuous in LPS-stimulated cells. In contrast, PHA and SEB produced few blast cells which contained significant rough ER. The morphologic observations are consistent with the hypothesis that the mitogenic effect of endotoxin is on bone-marrow-derived lymphocytes. This effect may relate to the known adjuvant effect of endotoxin in vivo.

Animals↗
PubMed1972

Endotoxin-induced hepatic damage in BCG-infected mice.

Systemic infection of mice with Mycobacterium BCG leads to focal liver damage by producing many granulomas. By undefined mechanisms, this infection markedly enhances the animal's susceptibility to the lethal effect of endotoxin. Small doses of endotoxin given to BCG-infected mice were found to cause acute hepatic damage, as demonstrated by elevated activities of liver enzymes in serum and by morphologic alterations documented by light and electron microscopy and by histochemical technics. The morphologic alterations caused by endotoxin included glycogen depletion, mitochondrial swelling, disruption of the continuity of sinusoidal endothelium and focal injury characterized by marked vacuolization of hepatocytes and distension and fragmentation of rough endoplasmic reticulum. Histochemical studies revealed the apparent release of acid phosphatase from granules in the central portions of granulomas, and the release of beta-glucuronidase from the cytoplasm of hepatocytes.

Acid Phosphatase↗
PubMed1971

Evidence for a bilayer structure in gram-negative lipopolysaccharide: relationship to toxicity.

Additional evidence for a bilayer structure in isolated gram-negative lipopolysaccharide (LPS) is demonstrated. Both heating in an electron beam and cleavage of ester-bound fatty acids by alkali were found to split the bilayer structure of LPS into apparent monolayers. The altered structure of LPS resulting from alkaline hydrolysis may explain some of the altered biological activities possessed by the hydrolyzed product.

Alkalies↗
PubMed1971

Effect of alkali-treated lipopolysaccharide on erythrocyte membrane stability.

The interaction of various lipopolysaccharides (LPS) with sheep erythrocytes was studied. When subjected to mild alkaline hydrolysis, the affinity of LPS for the red cell surface was greatly increased, as others have reported. In addition, excessive quantities of alkali-treated LPS (but not parent or heated products) were found to cause hemolysis of red cells. Experiments indicated that the hemolysis was caused by the LPS particles themselves and not by liberated free fatty acids.

Alkalies↗
PubMed1970

Salmonellosis in Mice Infected with Mycobacterium bovis BCG II. Resistance to Infection.

Mycobacterium bovis BCG-infected mice were found to be consistently more resistant than normal mice to superinfection with Salmonella typhimurium. This resistance was manifested by a decreased mortality and by a decrease in the number of viable Salmonella in the BCG mice 3 to 4 days after challenge. Antibody production, as determined in the serum by the complement-dependent bactericidal system or in the spleen by the Jerne plaque technique, was either equivalent to or less than that of normal mice. Therefore, the immunity to S. typhimurium possessed by BCG-infected mice cannot be the expression of a greater or more rapid antibody response. By exclusion, these findings appear to support the concept of "cellular immunity."

Journal Article↗
PubMed1970

Effect of Alkali on the Immunological Reactivity of Lipopolysaccharide from Salmonella typhimurium.

The effect of mild alkaline hydrolysis on the immunological reactivity of Salmonella typhimurium lipopolysaccharide (LPS) was studied. Hydrolysis of LPS at 37 C in 0.01 to 0.25 n NaOH caused a decrease in precipitation of LPS by antiserum. Red cells sensitized with alkali-treated LPS were less responsive to hemagglutination by antiserum than were cells sensitized with heated LPS. Hemagglutination-inhibition studies showed that alkali-treated S. typhimurium LPS was antigenically deficient. Alkaline hydrolysis of S. typhimurium LPS destroys antigen 5 of the Kauffmann-White scheme by cleavage of O-acetyl groups. However, abequose, the immunodominant sugar for antigen 4, is also cleaved from the O side chains by alkali, suggesting the loss of more than one antigenic determinant. It is concluded that alkali treatment of LPS to promote the sensitization of red cells may alter the serological specificity and therefore places limitations on its use in serological studies.

Journal Article↗
PubMed1969

Hypoglycemic activity of endotoxin. II. Mechanism of the phenomenon in BCG-infected mice.

The mechanism of the hypoglycemic activity of endotoxin in hyperreactive BCG mice was investigated. The mechanism was found to be an inhibition of the synthesis of glucose from noncarbohydrate sources. The possibilities of an induced hypermetabolic state and an induced release of insulin in response to endotoxin as causes for the hypoglycemic response were essentially ruled out. In addition, no clear-cut evidence of an insulin-like action by endotoxin was found in the in vivo setting.

Animals↗