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Biomedical subjects

J Hamburger

Publications and source records attributed to J Hamburger.

At least 19 recordsLinked to original sources
PubMed1992

Identification of schistosome-infected snails by detecting schistosomal antigens and DNA sequences.

Cercarial shedding tests do not provide species identification of the schistosomes concerned and cannot detect prepatent schistosomal infections. We have demonstrated that both immunodetection by ELISA of schistosomal antigens in snail hemolymph, and dot hybridization of snail extracts by a DNA probe representing highly repeated sequences, proved suitable for detecting infected snails during prepatency as well as patency. A group-specific monoclonal antibody was found to be suitable for detecting Schistosoma mansoni infection in Biomphalaria sp., but not for positive identification of S. haematobium in Bulinus sp. Comparative evaluation of the diagnostic qualities, and technical aspects and cost of these tests, point to the superiority of the immunodetection approach for large scale detection of snails prepatently infected with S. mansoni. This approach is potentially useful for providing extended information on schistosome-snail epidemiology that may facilitate rapid evaluation of the danger of post-control reinfection, and help make decisions on the time and place of supplementary control measures. In this context the potential usefulness of the immunodetection or DNA probing approach for facilitating catalytic model representation of schistosome-snail epidemiology warrants further evaluation. Specific identification of S. haematobium in Bulinus by either of these approaches may be possible depending on the development of suitable antibodies or DNA probes.

Animals↗
PubMed1979

[Production of urea during mixed leukocyte culture (MLC). Effect of presensitization by a skin allograft].

An increased production of urea has been demonstrated during mixed cultures between allograft donor and recipient leukocytes. This phenomenon may also be observed during primary MLC (i.e, without previous allograft) but to a lesser degree. This increased production of urea during MLC results from an increase of arginase activity in spleen cell population(s) resulting in an increased arginine transformation into urea and ornithine, as demonstrated by the release of an amount of ornithine equivalent to that of urea in the culture supernatant.

Amino Acids↗
PubMed1978

[Functional inhibition of isolated pancreatic cells, new technic for the detection of macrophage cytotoxicity].

It is usually accepted that macrophages "activated" by lymphokines may be found cytotoxic against tumoral target cells but show no detectable cytotoxicity in in vitro tests using normal non tumoral cells as target cells. These data have been obtained mainly with the chromium-release test. The present paper describes a new test using normal isolated pancreatic cells as target cells and evaluating the effect of activated or non-activated macrophages on the insulin secretion response to glucose stimulation. The results show a striking decrease in this response following an 18-hr incubation of pancreatic islet cells with activated macrophages, as compared to that of the same cells incubated with control macrophages. This is clear evidence that activated macrophages may alter normal cells and suggests that their cytotoxic properties are not restricted to tumoral target cells.

Animals↗
PubMed1978

Effect of thioglycollate on macrophage lysosomal enzymes.

Mice peritoneal macrophages obtained after i.p. injection of a medium containing thioglycollate (Institut Pasteur, Paris) have increased levels of beta glucuronidase and acid phosphatase, when compared with macrophages obtained without previous thioglycollate injection. The maximum increase is observed between 7 and 10 days after injection and reaches up to 3 to 4 times the normal activity. When using separately the various components of the medium, the same phenomenon may be observed but never to the same degree. The injection of thioglycollate also produces: a) an increase in total number of peritoneal cells, and b) an increase in the percentage of macrophages among these cells. Kinetic studies suggest that thioglycollate injection first induces an increase in the number of peritoneal macrophages and subsequently macrophage modifications resulting in lysosomal enzyme increase.

Acid Phosphatase↗
PubMed1977

Kinetics of immunological responses, resistance to reinfection, and pathological reactions to infection with Trichinella spiralis.

Changes in immune responses, resistance to reinfection, and pathological reactions were studied serially in mice that had been infected for four to 40 weeks with 150 larvae of Trichinella spiralis. Immediate footpad hypersensitivity reactions to antigens of Trichinella were present throughout the period of observation. Delayed hypersensitivity reactions 48 hr after injection of antigen were first seen in mice infected for 14 weeks and gradually increased in size thereafter. Intestinal adult worm burdens were determined one week after challenge with 5000 larvae. There was resistance to reinfection and accelerated expulsion of worms in animals challenged three weeks after the primary infection; this resistance waned at seven and 13 weeks but reappeared in mice infected for 20 weeks or longer. Counts of larvae in muscle were determined four weeks after challenge with 5000 larvae. Marked resistance was present four weeks after the primary infection and was maintained for the duration of the study.

Animals↗
PubMed1976

Presence of antigen-antibody complexes in antiallogeneic and antixenogeneic sera.

Antilymphocyte sera (ALS), either allogeneic (for example, Lewis anti-August rat serum) or xenogeneic (the classic ALS), may retain the antigen used for the immunization of the animal producing the serum in the form of antigen-antibody complexes, at least when the animal is bled within the first 2 weeks following the last immunizing injection. Evidence for this has been obtained in vivo and in vitro. In vivo experiments showed that injection of Lewis anti-August serum to a normal Lewis rat can induce a delayed active immunization against the August strain. In vitro studies proved the presence of August antigens in the anti-August sera, by precipitation of the antigen-antibody complexes with 6 M urea, removal of the antibody by filtration, and demonstration that the filtrate specifically inhibits complement-dependent cytotoxicity of anti-August antibodies. The interpretation of a number of previous works on so-called passive enhancement of grafts or on various effects of ALS may have to be reconsidered on the basis of these findings.

Animals↗