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Biomedical subjects

R Brun

Publications and source records attributed to R Brun.

At least 73 records · Page 4Linked to original sources
PubMed1981

In vitro cultivation of bloodstream forms of Trypanosoma brucei, T. rhodesiense, and T. gambiense.

A series of new in vitro systems for the cultivation of bloodstream forms of Trypanosoma (Trypanozoon) brucei brucei, T. (T.) b. rhodesiense, and T. (T.) b. gambiense was developed. The standard system consists of a feeder layer of fibroblast-like cells derived from embryos of New Zealand White rabbits (REF( or a mountain vole, Microtus montanus (MEF), with HEPES-buffered Minimum Essential Medium (MEM), with Earle's salts, supplemented with 15% inactivated rabbit serum. These two and other feeder layers were cross-checked with different sera to test for growth support of bloodstream forms of the three trypanosome subspecies studied. Cultures could be initiated with bloodstream forms from mammalian hosts or from cryopreserved stabilates. Metacyclic forms from infected Glossina m. morsitans could also be sued as inoculum; they transformed within 6 h to bloodstream forms. Maintenance of cultures and growth properties are described in detail. Experiments were undertaken to confirm that the cultivated bloodstream forms still possess some fo the characteristic features of pleomorphic bloodstream populations. Cultivated bloodstream forms were always infective for mice, and a surface coat could be demonstrated by electron microscopy. They could also be cyclically transmitted through tsetse flies, and the metacyclic forms from these flies could be brought back into culture. In vitro cloning with single bloodstream forms and metacyclic forms could be achieve with high cloning efficiency. The consumption of glucose and the production of pyruvate and lactate were determined.

Animals↗
PubMed1980

Pyrazolopyrimidine metabolism in African trypanosomes: metabolic similarities to Trypanosoma cruzi and Leishmania spp.

Growth inhibition and radioisotope incorporation studies with allopurinol (4-hydroxypyrazolo(3,4-d)pyrimidine) have shown that the African trypanosomes are biologically and biochemically similar to Leishmania spp. and Trypanosoma cruzi with respect to their response to this compound. These organisms, as a group, share the unique ability to convert allopurinol sequentially to its ribonucleoside monophosphate and 4-aminopyrazolo(3,4-d)pyrimidine ribonucleoside mono-, di- and triphosphates.

Allopurinol↗
PubMed1980

Characterization of Trypanosoma brucei isolated from lymph nodes of rats.

Forms of Trypanosoma brucei isolated from lymph nodes of cyclically or intravenously infected rats, at different stages of infection, were morphologically compared with the corresponding bloodstream forms. Unlike the pleomorphic bloodstream trypanosome population, the lymph node trypanosome population was essentially monomorphic and resembled the slender forms of the bloodstream. Values for the morphometric parameters indicated a position between the slender and the stumpy forms. The number of trypanosomes/ml of blood showed the well-known periodic fluctuations while the number of trypanosomes/g of lymph node remained fairly constant. Serology revealed that lymph node trypanosome populations differed antigenically from the trypanosome populations isolated simultaneously frrom the bloodstream.

Animals↗
PubMed1980

Hydroxyurea: effect on growth, structure, and [3H]thymidine uptake of Trypanosoma brucei procyclic culture forms.

Hydroxyurea (HU) in concentrations above 50 micrograms/ml reversibly inhibited cell division of Trypanosoma brucei brucei stock STIB 336 procyclic culture forms, but not growth of individual cells. The volume of the nucleus and of the cytoplasm increased in the presence of the drug as did the percentage of cells with 2 kinetoplasts. Electron microscopy revealed that the nuclear membrane was extended forming protrusions which surrounded areas of the cytoplasm. Replication of the kinetoplast DNA did not seem to be affected by HU. The uptake of [3H]thymidine increased in the presence of 25 micrograms/ml HU 3-fold compared to control cells. The nuclear volume and the dry weight of the culture forms increased proportionally to the amount of label incorporated.

Animals↗
PubMed1980

Lack of delayed reaction in presence of cell-mediated immunity in trichophytin hypersensitivity.

Five patients with atopy who had chronic dermatophytosis manifested an immediate and strong trichophytin skin reaction but no delayed reaction. This phenomenon may be caused by the neutralization of injected antigen by serum antibodies during the immediate reaction. When we injected a second dose of trichophytin into the wheal of the immediate reaction, 20 minutes after the first injection, a strong delayed reaction was elicited, demonstrating cell-mediated immune responses in these patients.

Adolescent↗
PubMed1979

Nickel in food: the role of stainless-steel utensils.

Nickel may be found in prepared foods (tinned foods) at markedly higher concentrations than the safe threshold laid down for hypersensitive patients. Some foodstuffs cooked in stainless-steel utensils attack the metal and thus contain much more nickel than when enamel or aluminum saucepans are used. Among the natural organic acids which may be responsible for dissolving stainless-steel, oxalic acid is the most active at equivalent concentrations.

Cooking↗
PubMed1979

[Guinea pig nipple as a model for the investigation of melasma (author's transl)].

The nipples of male tan guinea pigs were used to test the effects on the skin of oral contraceptive pills and drugs. The daily topically applied doses were 1/2,000 of a pill. After 3 weeks, the nipples treated with solutions of ethinyloestradiol-containing pills had grown (200-300%), the epidermis showed acanthosis (150-250%) and strong hyperpigmentation. Mestranol-containing pills as well as pure progestogen substances did not produce these effects.

Animals↗