1,721,140 research outputs found
LYMPHOCYTES-B AND LYMPHOCYTES-T REGULATED BY IDIOTYPE ANTIIDIOTYPE INTERACTIONS INHIBIT DELAYED-TYPE HYPERSENSITIVITY TO BCG IN MICE
No full textMice infected subcutaneously with 2 X 10(7) CFU of Mycobacterium bovis strain BCG (BCG) were able to mount a specific DTH response, whereas mice infected intravenously with the same dose of microorganisms were not. The suppression turned out to be mediated by id+ anti-PPD B lymphocytes, which arose very early during the infectious process and induced anti-id B lymphocytes. These cells were found at Day 4 after infection and exerted their effect by activating antigen-specific suppressor T lymphocytes, which affected the efferent phase of the DTH response. These results clearly indicate that the activation of a complex immunosuppressive circuit represents a mechanism by which BCG may interfere with the host's immune response already during the very early phases of infection
IMMUNODEPRESSION BY ROWSON-PARR VIRUS IN MICE - EFFECT OF ROWSON-PARR VIRUS AND FRIEND LEUKEMIA COMPLEX INFECTIONS ON BACKGROUND ANTIBODY-FORMING-CELLS TO VARIOUS ERYTHROCYTES
No full textThe numbers of background antibody-forming cells (BPFC) toward erythrocytes of various species present in the lymphoid organs of unimmunized susceptible BALB/c and resistant C57BL/6 mice were investigated at various times after infection with Friend leukemia complex (FLC) or Rowson-Parr virus (RPV). Both virus preparations induced an increase of BPFC numbers in both animal strains, but the rate and magnitude of the enhancements produced by RPV were much lower. The degree of potentiation varied with the specificity of the BPFC populations and was more pronounced in the spleen than in the lymph nodes and in BALB/c than in C57BL/6 mice. In the late stage of FLC infection, the numbers of splenic BPFC to some erythrocytes underwent a dramatic fall, which was not observed in RPV-infected mice. BPFC present in BALB/c splenocytes cultured in diffusion chambers implanted in the peritoneal cavity of isogeneic normal mice were not affected by viral infection of the chambers
DEPRESSION OF CONTACT SENSITIVITY AND ENHANCEMENT OF ANTIBODY-RESPONSE IN PSEUDOMONAS-AERUGINOSA-INFECTED MICE
No full textThe effect of Pseudomonas aeruginosa infection on contact sensitivity to 2-phenyl-4-ethoximethylene-oxazolone (oxazolone) and on antibody response to sheep erythrocytes, horse erythrocytes, and Escherichia coli 0111:B4 lipopolysacharide was investigated in outbred C57BL/6 mice. Injection of 0.5 and 0.2 median lethal doses significantly depressed contact sensitivity to oxazolone, whereas injection of 0.5 median lethal dose of heat-killed microorganisms did not. The filtrate of a 24-h broth culture did not affect contact sensitivity as well. Antibody production against sheep erythrocytes, horse erythrocytes, and lipopolysaccharide (evaluated as plaque-forming cells and circulating hemagglutinin and hemolysin titers) was found to be significantly enhanced both in animals injected with living bacteria and in those which received heat-killed microorganisms. The simultaneous occurrence of depression of cell-mediated immunity and potentiation of humoral response suggests that P. aeruginosa might interfere at different levels of the host immunological responsiveness
IMMUNODEPRESSION BY ROWSON-PARR VIRUS IN MICE - EFFECT OF ROWSON-PARR VIRUS AND FRIEND LEUKEMIA COMPLEX INFECTIONS ON CONTACT SENSITIVITY IN SUSCEPTIBLE AND RESISTANT MICE
No full textContact sensitivity to 2-phenyl-4-ethoxymethilene oxazolone, as a probe for cell-mediated immunity, was investigated in susceptible BALB/c and resistant C57BL/6 mice after infection with Friend leukemia complex (FLC) or with Rowson-Parr virus (RPV). In BALB/c mice, FLC depressed contact sensitivity when given before primary sensitization but had no effect on established contact sensitivity nor on the response elicited by a booster application of the sensitizer. These findings, together with the failure to alter reactivity to an aspecific inflammatory stimulus, indicate that FLC impairs the afferent limb of the response. In the same strain of mice RPV infection did not significantly depress contact sensitivity, as judged by the extent of the reaction 24 h after challenge, but slightly inhibited the early antibody-mediated phase of this reaction. In C57BL/6 mice neither viral preparation affected contact sensitivity
Enhanced resolution of random amplified polymorphic DNA genotyping of Pseudomonas aeruginosa
No full textAims: To develop a rapid, sensitive and reproducible screening test for the detection of nosocomial spreading of Pseudomonas aeruginosa.
Methods and Results: Ps. aeruginosa genomic DNA extraction, RAPD-PCR, electrophoresis on acrylamide gel and silver staining were performed by using standardized reagents and conditions. The results were compared with the agarose gel electrophoresis followed by ethidium bromide staining.
Conclusions: The coupling of acrylamide gel electrophoresis and silver staining gave about 80% more DNA bands than the traditional method, allowing a finer discrimination among different Ps. aeruginosa strains.
Significance and Impact of the Study: By enhancing the resolution of the electrophoretic separation and the sensitivity of the staining, random amplification could be easily applied to the surveillance and prevention of nosocomial infections by clinical microbiology laboratories
THERMORESISTANCE AND CHRONORESISTANCE OF BACILLUS-STEAROTHERMOPHILUS OBTAINED AT DIFFERENT INCUBATION TEMPERATURES
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