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Biomedical subjects

S Pellet

Publications and source records attributed to S Pellet.

13 recordsLinked to original sources
PubMed2007

Individual monitoring for internal exposure of workers: regulation and practice in Hungary.

Decree of Ministry of Health for the enforcement of the Act on Atomic Energy has put special emphasis on the regulation of monitoring for internal exposure in Hungary. The necessarily general prescription of the Decree called for a guidance to assist the work of the competent authority. The Guide was elaborated on the basis of the IAEA Safety Guide No. RS-G-1.2. According to the IAEA Safety Guide the decision factor shall first be determined for the potential radionuclides and practice applied. For routine monitoring the required frequency, method and MDA values, moreover for special monitoring the method and MDA values were derived for over 50 radionuclides considering two basic assumptions: the activity remaining in or excreted from the body could be determined by the given measurement method and the possible underestimation of intake shall be less than a factor of 3 within the monitoring interval.

Algorithms↗
PubMed1995

Binding of antibodies to functional epitopes on the pore formed by Escherichia coli hemolysin in cells and model membranes.

Escherichia coli hemolysin (HlyA) inserts into target membranes producing a cation-selective pore. We approached the problem of determining which portions of this protein remain exposed on the side of attack by applying specific antibodies. Results obtained with resealed erythrocyte ghosts and planar phospholipid membranes were compared. The effects of one polyclonal and four monoclonal anti-hemolysin antibodies (mAbs) were studied. Using ghosts we found one mAb which strongly reduced the ion-permeability through the preinserted HlyA channels and one which clearly increased it. Experiments with planar bilayers corroborated these results by showing that the former mAb effectively promoted the closed state of the channel whereas the latter forced the HlyA channel into an open configuration. Anti-hemolysin polyclonal antibodies initially stimulated but then prevented channel opening, indicating they contained clones able to act on both these channel determinants. They were effective only when applied on the same side as the hemolysin indicating that the epitopes were exposed to that side. Finally, the antigenic epitopes of three of the mAbs were localised on the HlyA molecule by using different mutants (amber and frame shift mutants and hemolysin gene hybrids).

Animals↗
PubMed1995

Antibiotics in the preservation of allograft and xenograft skin.

The application of antibiotics in the preservation of allograft and xenograft skin is controversial. The penicillin-streptomycin combination that is commonly used in reports in the literature was ineffective in our practice. Our Tissue Bank has tested different antibiotic combinations and found a more effective and suitable combination. After aseptic retrieval of pig and cadaver split skin, the skin strips were incubated in Eagle's MEM containing different antibiotic combinations. From frozen and fresh allogeneic and xenegeneic skin, 1-cm2 pieces were incubated in bacterial growth media, then tested. The antibiotic effect on skin samples of the highest antibiotic concentrations was assessed by growth inhibition around the skin discs. We followed up the clinical results after skin transplantation. The best results were obtained using the following antibiotic combination: 1000 mg/l ceftazidime, 1000 mg/l ampicillin and 80 mg/l amphotericin. The skin retained its antimicrobial effect after freezing and thawing. In 1992, 5 m2 cadaver and 50 m2 pig split skin were supplied to the Hungarian burn centres to cover deep partial and full skin thickness burned patients. There has not been a graft-originated infection during this period.

Amphotericin B↗
PubMed1994

Pore-formation by Escherichia coli hemolysin (HlyA) and other members of the RTX toxins family.

Escherichia coli hemolysin (HlyA) is a major cause of E. coli virulence. It lyses erythrocytes by a colloid osmotic shock due to the formation of hydrophilic pores in the cell wall. The size of these channels can be estimated using osmotic protectant of increasing dimensions. To show that the formation of pores does not depend critically on the osmotic swelling we prepared resealed human erythrocyte ghosts loaded with a fluorescent marker. When attacked by HlyA the internal marker was released, indicating the formation of toxin channels so large as to let it through. The channels can be directly demonstrated also in purely lipidic model systems such as planar membranes and unilamellar vesicles, which lack any putative protein receptor. HlyA has been recognised as a member of a large family of exotoxins elaborated by Gram-negative organisms including Proteus, Bordetella, Morganella, Pasteurella and Actinobacillus. These toxins have quite different target cell specificity and in many cases are leukocidal. When tried on planar membranes however, even specific leukotoxins open channels not dissimilar from those formed by HlyA, suggesting this might be a common step in their action. Comparison of the hydrophobic properties of six members of the toxin family indicates the presence of a conserved cluster of ten contiguous amphipathic helixes, located in the N-terminal half of the molecule, which might be involved in channel formation.

Bacterial Proteins↗
PubMed1994

Radiation doses to those accompanying nuclear medicine department patients: a waiting room survey. EANM Task Group Explaining Risks. European Association of Nuclear Medicine.

In a multi-centre European trial we have assessed the radiation dose to those accompanying patients undergoing nuclear medicine investigations. Dosemeters were first calibrated against each other and then used to measure the radiation dose to the nurse or relative while they were in the waiting room. In departments where there was one waiting room the median radiation dose was 13 microSv, and the corresponding figures for where there were two waiting rooms and where the patients were allowed to leave the department with their nurse or relative were 12 and 11 microSv, respectively. These figures are not significantly different. However, we found that the median radiation dose to relatives was 13 microSv while that to nurses was 3 microSv (P < 0.01), although the waiting times were not significantly different. The reasons for these differences are discussed. Our data do not support the need for a second waiting room for injected patients in a nuclear medicine department.

Calibration↗
PubMed1983

Stimulation of human peripheral lymphocytes with endotoxin and radiodetoxified endotoxin.

The effects of parent endotoxin and radiodetoxified endotoxin on human peripheral lymphocytes were compared in experiments in vitro. Radiodetoxified endotoxin is able to exceed the degree of the stimulation induced by parent endotoxin and its stimulatory effect. At the same time, no change was observed in the presence of autologous serum. Radiodetoxified endotoxin did not inhibit the phytohaemagglutinin-induced proliferative response.

Cells, Cultured↗