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Biomedical subjects

R Thomssen

Publications and source records attributed to R Thomssen.

At least 109 records · Page 6Linked to original sources
PubMed1975

Target cell-dependent T cell-mediated lysis of vaccinia virus-infected cells.

Vaccinia virus specific cytotoxicity against infected target cells was observed in vitro. Spleen lymphocytes from normal and immunized mice of the inbred strains C3H and DBA/2 were incubated with vaccinia virus-infected and non-infected 51 Cr-labeled mastocytoma P-815-X2 cells and L-929 fibroblasts, which were used as targets. Cytotoxic lymphocytes could be isolated from the mice as early as 2 days after infection with vaccinia virus. The highest cytotoxic effect was obtained with lymphocytes taken 6 days after infection. The degree of lysis was correlated with the ratio of immune lymphocytes to target cells. Specific blocking of target cell lysis resulted after addition of anti-vaccinia antibody from different sources. The effector cells could be characterized as T cells by elimination of macrophages and B cells. Target cell killing was only possible in a syngeneic system; allogeneic infected target cells were not lysed significantly.

Animals↗
PubMed1975

Interactions between vaccinia virus and sensitized macrophages in vitro.

The action of peritoneal exudate cells (PEC) from normal and vaccinia virus infected mice on infectious vaccinia virus particles was investigated in vitro. PEC from immune mice showed a significantly higher infectivity titre reduction (virus clearance, VC) than normal cells. This effect could be clearly attributed to the macrophage. Vaccinia virus multiplied in PEC from normal animals while there was no virus propagation in cells from immunized mice. The release of adsorbed or engulfed virus was reduced significantly in PEC from immunized animals. Anti-vaccinia-antibodies seem to activate normal macrophages to increased virus clearance. This stimulating effect was demonstrable only in the IgG fraction of the antiserum. The activity of macrophages from mice injected three times over a period of 14 days with vaccinia virus could be entirely blocked with anti-mouse-IgG, while PEC from mice injected one time six days previously were not inhibited.

Animals↗
PubMed1975

Live attenuated versus killed virus vaccines.

The discussion of the problems of production and use of killed and live virus vaccines shows that the theoretical, basic concepts of the alternative vaccination procedures are equivalent in regard to the ideals of calculable potency and safety. If one compares the present stages of development, then it becomes evident that the advantages of live viral vaccination are due to greater potency. However, killed virus vaccines are safer. Nevertheless, these differences are not without limits. In some vaccinating procedures, the live virus vaccine is the safer of the two.

Adult↗
PubMed1975

Standardized detection of hepatitis B surface antigen: determination of its serum concentration in weight units per volume.

The concentration of HBsAg in serum was determined in arbitrary units by quantitative immunoelectrophoresis and in units of optical density by UV-photometry of purified antigen. The HBsAg was purified from serum by gelchromatography and subsequently by isopycnic centrifugation in cesium chloride. The ratio of the immunoelectrophoretically measured concentration to the units of optical density was found to be constant in six different samples with both subtypes - ad and ay - and varying concentration. The concentration of protein in three purified HBsAg samples was determined after acid hydrolysis by automatic aminoacid analysis. The specific extinction was E1 280 mg/ml = 4,5 +/- 0,3. Thus the arbitrary units of immunoelectrophoresis were converted to concentration of HBsAg specific protein, expressed as mug/ml. In 540 Ausria positive serum samples, mainly from the beginning of an acute hepatitis, 10-40 mug/ml was the most frequent range of concentration. About 4% of the sera contained more than 100 mug/ml, about 20% contained between 0,005 and 0,5 mug/ml and were positive only in RIA. 10 mug/ml correlated with titers in complement fixation of 1:32/64, in counterimmunoelectrophoresis of 1:8 and immuno-diffusion of 1:2. The use of standards with a defined concentration of HBsAg would allow a better control of the sensitivity in qualitative tests and of reproducibility in quantitation.

Animals↗
PubMed1975

Direct solid-phase radioimmunoassay (dSP-RIA) for detection of antibody to hepatitis B surface (HBs) antigen.

Using direct solid-phase radioimmunoassay (dSP-RIA) which was shown to be specific and about 10000 times more sensitive than immunodiffusion and even 10 times more sensitive than the radioimmunoprecipitation test used by us before, anti-HBs was detected in 90% of hepatitis B convalescents who were followed up for a one year observation period and who had eliminated HBs antigen from their sera (60/68). In 13% of these patients (8/60 anti-HBs was only temporarily detectable. In 50% of all patients who developed antibody within a two to twelve months observation period (n = 151), anti-HBs appeared within three to four months after height of disease. In 16.5% of patients with HBs antigen negative hepatitis (32/193) anti-HBs was observed to develop during convalescence indicating a type B infection despite a negative finding for HBs antigen in the acute stage of disease. Using dSP-RIA anti-HBs was found in 5.5% of voluntary blood donors (n = 1036), in 20.2% of hospitalized patients without clinical hepatitis (n = 252), and in 30.6% of hospital staff (n = 304). Anti-HBs increases with age: in 14 year olds we found 0.5%, in 60 year olds, 14%. The fact that at least 70% of the anti-HBs positive normal persons and medical staff groups had no history of hepatitis illustrates the frequency and importance of subclinical hepatitis B infections.

Adolescent↗
PubMed1975

In-vitro demonstration of cell-mediated immunity to vaccinia virus in man.

Cell mediated immunity to vaccinia virus in man was studied by lymphocyte transformation. Vaccinia antigen, propagated on BHK-21 and Vero cells, could be used successfully for in-vitro testing after partial purification as well as crude infectious homogenates. Vaccinia antigen preparations were effective both in the infective and the inactivated state. Inactivation was usually accompanied with a certain loss of stimulating activity. Development of cell mediated immune response in-vitro after first vaccination was investigated in 17 adults. Vaccinia virus specific lymphocyte transformation was seen in the second week after vaccination in all cases. Following revaccination no increase of lymphocyte transformation ratio could be observed in 11 persons studied. At the same time the titers of humoral antibodies were elevated.

Adolescent↗
PubMed1975

[Significance of the antibacterial agent assay of urine for bacteriological diagnosis and control of chemotherapy of urinary tract infections (author's transl)].

The disc agar-diffusion-test using Bacillus subtilis ATCC 6051 as test organism is a simple and rapid method for routine testing of antibacterial agents in urine specimens. The test records urine levels which are expected under medium dosage, and in many cases even lower concentrations of renal excreted antibiotics. Out of 5655 analysed urine samples 22% contain antibacterial substances. In urine specimens over which information was volunteered that either no chemotherapy had been administered or that more than a three day's interval free of therapy existed, inhibitory substances are found in 8% and 27% respectively. Urine specimens which are supposedly collected from patients under current chemotherapy do not show therapeutic relevant antibiotic levels in 26%. Between urine specimens with and without antibacterial activity there is no significant difference in the incidence of viable counts of 10-4-10-5/ml and 10-5/ml. From urine samples with antibacterial content increases in the numbers of multiple resistant strains of E. coli, Proteus spp., Pseudom. aerug. and Enterobacter spp. together with high numbers of Candida spp. are observed.

Anti-Bacterial Agents↗