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Biomedical subjects

S Specter

Publications and source records attributed to S Specter.

At least 91 records · Page 5Linked to original sources
PubMed1983

Differential complement activation and susceptibility to human serum bactericidal action by Vibrio species.

The ability of Vibrio vulnificus to resist human serum bactericidal action and to activate human complement was compared with similar cultures of Vibrio cholerae and Vibrio parahaemolyticus. Both V. vulnificus and V. parahaemolyticus had similar survival rates in sera and were much more resistant to killing than was V. cholerae. In contrast, V. vulnificus activated significantly less serum complement than did V. cholerae and V. parahaemolyticus. The relative ability of V. vulnificus to survive in serum and activate less complement than other Vibrio spp. tested may be related to its ability to cause chronic tissue infections and septicemias.

Blood Bactericidal Activity↗
PubMed1981

Age- and sex-related differences in antibody formation and blastogenic responsiveness of splenocytes from RIII mice developing virus-induced mammary adenocarcinoma.

Inbred RIII mice, known to be infected neonatally with murine mammary tumor virus so that females develop mammary adenocarcinoma by 12-15 months of age, were examined with regard to antisheep red blood cell antibody responses at the cellular level. Female mice, 3-11 months old, compared to male mice of the same ages had consistent and significant depression of the antibody response of their splenocytes. Furthermore, female mice with adenocarcinoma showed an even greater depression of the antibody response. Spleen sizes were consistently increased in females as compared to those of male mice throughout the first year of life. The blastogenic responsiveness of the splenocytes to the B-cell mitogen Escherichia coli lipopolysaccharide and the T-cell mitogen phytohemagglutinin-P was not significantly different between male and female mice during the same periods, although the responses of the older tumor-bearing female mice to phytohemagglutinin-P were lower than those of non-tumor-bearing female mice. A complex relationship between age, sex, and immune responsiveness was evident in these mammary tumor virus-infected mice, which made it difficult to attribute a specific immune event to emergence of the mammary adenocarcinomas in the female as compared to male mice.

Adenocarcinoma↗
PubMed1979

Effect of immune sera upon enhanced in vitro antibody responses.

Immunization of rabbits with S marcescens bacteria in Freund's incomplete adjuvant resulted in development of anti-Serratia sera with bacterial agglutinating properties as well as LPS modulating properties. The antisera reacted with the LPS in counterimmunoelectrophoretic assays. Such antisera also stimulated the LPS induced enhancement of specific anti-SRBC responses from normal spleen cell cultures but did not further enhance the stimulated responses of similar cultures incubated with the smaller molecular weight PS-rich derivative. The antisera had no effect on LPS or PS enhanced nonspecific background anti-SRBC response as compared to normal rabbit serum-treated controls. These results point to a possible role for immune complexes as an enhancer of the immunostimulating activities of LPS antibody-treated cultures and also indicate a difference between LPS and PS as immunomodulators.

Animals↗
PubMed1979

Involvement of peritoneal macrophages in cellular responses to mastocytoma in resistant and susceptible mice.

The involvement of peritoneal macrophages in rejection of mastocytoma cells in the C57BL/6 mice was examined in comparison to similar cell responses in susceptible DBA/2 mice. By means of scanning and transmission electron microscopy it was found that macrophages constituted the major cell class responding to the mastocytoma cells in the peritoneum of both mouse strains. However, in the resistant mouse strain macrophages formed the predominant cell type during the course of tumor growth. Furthermore, tissue culture of peritoneal exudate cells from this resistant mouse strain injected with mastocytoma cells five days earlier failed to grow out tumor cells. On the other hand, macrophages decreased in number in the susceptible DBA/2 mouse strain and tumor cells did grow readily in vitro when peritoneal cells containing tumor cells and macrophages were cultured in vitro. These results indicate that macrophages constitute an important cell class in resistance of a mouse strain which is now susceptible to mastocytoma cells. The ultrastructural study provided some insight into the nature of the cell types involved and their interaction with the tumor cell.

Animals↗
PubMed1979

Factors from lymphoid cell tumor affecting immune responses.

Friend leukemia virus induces erythroblastic leukemia in genetically susceptible BALB/c mice. FLV-containing leukemic cells markedly depressed the humoral immune response to SRBC in the appropriate mouse strain. Both immunosuppression and leukemogenesis were readily transmitted by cell-free virus-containing homogenates of the FLV leukemic splenocytes into normal BALB/c mice. In the present study it was found that both Friend leukemic splenocytes as well as virus containing extracts from the leukemic cells were neutralized by heating and by specific antisera. Suppressive activity passed through a 0.45 mu filter but not a 300,000 MW filter and could be pelleted at 100,000 x g. They were also highly resistant to inactivation by irradiation. Mice given leukemic splenocytes after irradiation with up to 32.000 rads still developed leukemia. Addition of either normal or irradiated FLV-leukemic cells to normal spleen cell cultures in vitro markedly suppressed antibody formation. At least 32,000 rads were required to significantly impair the immuno-suppressive activity of the FLV-leukemic cells. Thus, virus per se appears to be directly responsible for suppression of antibody formation to FLV.

Animals↗
PubMed1978

Murine lymphoma-induced immunosuppression: requirement for direct tumour cell contact.

The FBL-3 lymphoma cell line caused impaired antibody formation in vivo when injected into mice intraperitoneally, and in vitro when added to normal syngeneic spleen cells immunized in vitro with sheep erythrocytes. Immunosuppression occurred only when intact viable tumor cells were cocultivated with the normal spleen cells. As few as 10(5) FBL-3 cells, when added to 5 X 10(6) normal cells, impaired antibody formation. However, cell-free extracts of filtrates from even much larger numbers of tumor cells did not affect antibody formation, either in vitro or in vivo. Heating the tumor cells at 56 degrees C or irradiation with as little as 1000 rads completely abolished immunosuppressive activity, both in vitro and in vivo. Separation of viable tumor cells from target antibody-forming cells by cell-impermeable membranes prevented immunosuppression, showing that direct cell-to-cell contact is required for immunosuppression.

Antibody Formation↗
PubMed1978

Scanning electron microscopy of lymphoid cells from leukemia virus-infected mice.

Spleen, lymph node, bone marrow, and thymus cells from Friend leukemia virus (FLV)-infected mice were examined by scanning electron microscopy. Whereas splenocytes from normal, noninfected animals showed the expected morphological classes of lymphocytes, including cells with numerous villous projections and smoother cell types, spleen cells from mice infected with FLV showed a rapid alteration of surface morphology. Shortly after infection, a decrease in the number and percentage of villous cells occurred, with a concomitant increase in the number of cells that were larger and smoother. Within 10 to 20 days after infection, the majority of splenocytes were smooth, large cells showing many distinct morphological charges, including surface "holes" and a "spongy" appearance. By days 25 to 35 after infection, most splenocytes were abnormal in appearance. Similar changes occurred in the lymph nodes after FLV infection, but the rate of change was much lower. Abnormal and larger smooth-surfaced cells did not become prominent until after week 2 or 3 infection. Thymus and bone marrow cells showed little if any change in surface morphology until late in the infectious process. However, even at that time only a few of the cells were abnormal in appearance. The changes in cell population in the spleen but not the lymph nodes paralleled the rapid decrease in the percentage of cells which stained positive for surface immunoglobulin and theta antigen. Futhermore, FLV antigen rapidly appeared on spleen cells after infection; fewer lymph node cells were positive, and only low numbers of marrow and thymus cells stained positive for FLV antigen. The marked immunosuppression induced by FLV infection paralleled and in some instances preceded the marked morphological changes.

Animals↗
PubMed1978

Tumor-induced immunosuppression.

Three tumor systems, including a mastocytoma, plasmacytomas, and a leukemia-lymphoma were studied for their ability to modify humoral immunity to sheep erythrocytes both in vivo and in vitro. All tumors resulted in a depression of the hemolytic antibody plaque-forming cell response in susceptible mice. These studies indicated that the mechanism(s) of suppression, although not fully defined, were different for each model system investigated.

Animals↗
PubMed1978

Stimulation of an enhanced in vitro immune response by a synthetic adjuvant, muramyl dipeptide.

Various subcellular bacterial fractions are known to enhance immune responses and serve as potent adjuvants. Muramyl dipeptide (MDP), a synthetic adjuvant mimicking a component of mycobacterial cell walls, enhances humoral immunity to soluble antigens and can increase macrophage cytotoxicity toward mastocytoma cells in vitro. In the present study MDP was found to enhance the hemolytic antibody plaque response of normal mouse spleen cells in vitro to SRBC at a level equal to or greater than that induced by Escherichia coli lipopolysaccharide. Furthermore, MDP was found to enhance the antibody response to SRBC nonspecifically in unimmunized spleen cell cultures, suggesting that similar to LPS the synthetic dipeptide may induce a generalized clonal expansion of committed lymphocytes and thus serve as a "polyclonal activator." MDP also enhanced the immune responsiveness of normal splenocytes to suboptimum concentrations of SRBC, indicating that this material may be useful in enhancing immunity in situations where there would normally be a poor immune response.

Adjuvants, Immunologic↗
PubMed1977

Detection of bacteriuria by automated electrical impedance monitoring in a clinical microbiology laboratory.

An apparatus capable of rapidly detecting changes in electrical impedance was utilized for the continuous monitoring of bacterial growth in routine urine specimens in a clinical laboratory. In a trial study, 200 clinical specimens analyzed by the electrical impedance method resulted in an average detection time of 2.5 h for 41 clinically significant specimens, whereas conventional methods for bacterial isolation required overnight culture. Those specimens positive by the electrical impedance monitoring but negative by conventional bacteriological methods accounted for less than 2% of the total number of positive specimens, whereas electrical impedance-negative but conventional culture-positive specimens accounted for ca. 4%. Electrical impedance apparatus in clinical microbiology laboratories could provide rapid screening of clinical urine specimens as well as accurate detection of bacterial growth.

Bacteria↗
PubMed1977

Rapid detection of bacterial growth in blood samples by a continuous-monitoring electrical impedance apparatus.

A growth detection method utilizing an automated apparatus capable of rapidly detecting bacterial growth by measuring changes of electrical impedance in bacteriological medium was utilized with "mock" blood cultures containing various gram-negative and gram-positive bacteria. Measurement of changes of electrical impedance was found to ba as accurate and comparable for time of growth detection as the radiometric method for detection of the same bacteria using mock blood cultures. In a limited clinical trial the use of the electrical impedance apparatus detected in 1 positive specimen from 40 clinical blood specimens as rapidly as by radiometric measurement. Both methods were considerably faster for detecting bacterial growth as compared with conventional culture methods. The selected species of gram-positive and -negative organisms tested were all detected by the electrical impedance method, including aerobes and anerobes. However, addition of 5% CO2 to the incubation atmosphere enhanced detection of gram-positive organisms.

Aerobiosis↗