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Biomedical subjects

G Michel

Publications and source records attributed to G Michel.

At least 379 records · Page 21Linked to original sources
PubMed1988

Bacillomycins Fb and Fc: isolation and characterization.

Bacillomycins Fb and Fc, new antifungal antibiotics, were isolated from a strain of Bacillus subtilis producing bacillomycin F. Because of the presence of beta-amino acids, these compounds belong to the iturin group. The acid hydrolysates contained alpha-amino acids Asp3, Glu1, Pro1, Thr1, Tyr1 and a mixture of iso-C15, anteiso-C15, iso-C16, iso-C17 and anteiso-C17 beta-amino acids. The ratios of the different beta-amino acids depend on the nature of the culture medium. Bacillomycins Fb and Fc differ from bacillomycin F by the presence of free carboxyl groups.

Amino Acid Sequence↗
PubMed1988

Repeated courses of high dose melphalan and unpurged autologous bone marrow transplantation in children with acute non-lymphoblastic leukemia in first complete remission.

Eleven children between the ages of 1 and 16 years with acute non-lymphoblastic leukemia (ANLL) in first remission were included in a study of double unpurged autologous bone marrow transplantation (ABMT). Prior to each ABMT patients received massive chemotherapy with melphalan at a dosage of 140 mg/m2. The first ABMT was done within a median of 4 months after the achievement of complete remission. As soon as the children had adequate hematologic recovery, a second marrow collection was done, followed by a second course of melphalan and a second ABMT. The duration of aplasia was significantly longer after the second ABMT than after the first, but the non-hematologic toxicity was relatively mild in each case and no patient died from the procedure. Four patients relapsed and seven are alive in unmaintained complete remission with a median duration of leukemia-free survival of 29 months (range 15-56 months) after the first ABMT. These data demonstrate the feasibility of repeating ABMT after melphalan in children with ANLL. The eventual impact of such therapy needs to be demonstrated in prospective randomized studies.

Adolescent↗
PubMed1988

[Bacteremias after bone marrow grafts in a protected environment: effects, various aspects and prognosis].

We evaluated retrospectively the incidence and prognosis of bacteremias after bone marrow transplantation treated in protected environment with intestinal decontamination. Bacteremias are more frequent during the extreme granulopenia (55% of the patients) than during recovery of granulocyte counts greater than 500/mm3 (35% of the patients). Gram + organisms are more frequently responsible of bacteremias (80%), mainly Staphylococcus epidermidis and Streptococci. Mortality is low (7%) and related to additional factors like GVH, resistant leukemia. These data invite to develop new approaches of prevention of bacterial infection, with measures possibly efficient on Gram + organisms.

Adolescent↗
PubMed1988

[Enzymatic cleavage of human neurophysin into 2 sub-domains containing 3 and 4 disulfides].

Native human MSEL-neurophysin has been subjected to trypsin hydrolysis. Because of a change of the bond Lys59-Pro60 found in other mammalian neurophysins into Lys59-Ala60 in human protein, a peculiar cleavage has occurred in the latter, leading to a split of the molecule into two halves. The N-terminal sub-domain contains 4 disulfide bridges whereas the C-terminal one possesses 3 disulfide bridges.

Amino Acid Sequence↗
PubMed1988

Poor prognosis of acute lymphoblastic leukemia with translocation (1;19) in childhood: potential interest of allogeneic bone marrow transplantation.

We report a new case of childhood acute lymphoblastic leukemia with translocation (1;19). At the time of diagnosis, the only adverse prognosis factor was the existence of this translocation. Under conventional chemotherapy, the girl experienced early marrow relapse (duration of first remission was 2 months). She received allogeneic bone marrow transplantation during the second remission and is alive in continuous complete remission 20 months after transplant. Several earlier reports have suggested that children with the (1;19) have a poor prognosis; If this poor response to conventional therapy is confirmed, an allogeneic bone marrow transplantation should be considered during the first remission.

Bone Marrow Transplantation↗
PubMed1988

Partial chimerism after T-cell-depleted allogeneic bone marrow transplantation in leukemic HLA-matched patients: a cytogenetic documentation.

We evaluated serially by cytogenetics the blood and marrow chimerism of 38 leukemic recipients of HLA-matched bone marrow transplants (BMT) who were prepared by high doses of alkylating agents and fractionated total-body irradiation (2.2 Gy X 5). Donor or host mitoses were identified by examination of sex chromosomes in 32 patients or by evaluation of the polymorphism of other chromosomes after specific banding in six patients. Twenty-four patients were recipients of untreated BMT, and 14 were recipients of T-cell-depleted BMT. In the 24 patients who received untreated BMT, all showed successful engraftment, and only three had a transient mixed chimera. In the 14 recipients of T-cell-depleted BMTs, four rejected their grafts, and seven had mixed chimeras; these mixed chimeras were more frequent in blood lymphocytes than in marrow cells and could be detected up to 26 months after BMT. This high frequency of partial chimerism after T-cell-depleted BMT by comparison with a control group suggests that the donor's T cells play an important role in the eradication of host residual hematopoiesis after allogeneic BMT.

Adolescent↗
PubMed1988

[Syndrome of activation of the mononuclear phagocyte system. Initial manifestation of visceral leishmaniasis].

We report a case of mononuclear phagocyte system activation observed in a 12 month-old girl presenting with fever, hepatosplenomegaly, pancytopenia, histiocytic hyperplasia with hemophagocytosis in the bone marrow, high triglyceride and low fibrinogen blood levels. This syndrome was associated with visceral leishmaniasis. We conclude that systemic leishmaniasis is a curable cause of disorders characterized by an activation of the mononuclear phagocyte system.

Animals↗
PubMed1987

One-step processing of the amphibian vasotocin precursor: structure of a frog (Rana esculenta) "big" neurophysin.

Vasotocin-associated neurophysin (MSEL-neurophysin) from the frog Rana esculenta has been isolated and sequenced through tryptic and staphylococcal proteinase peptides and cyanogen bromide fragments. This protein appears homologous to the mammalian vasopressin-associated neurophysin with a C-terminal glycopeptide extension homologous to the mammalian copeptin. In contrast to the two-step processing of mammalian vasopressin/MSEL-neurophysin/copeptin precursor, a single cleavage is therefore involved in the processing of the amphibian vasotocin/neurophysin precursor. It appears that the physiological release of the vasopressin-like hormone from the N-terminal end of the protein precursor is not dependent upon a previous trimming of the C-terminal copeptin-like moiety.

Amino Acid Sequence↗
PubMed1987

Epidemiology of respiratory cancers related to nickel mining and refining in New Caledonia (1978-1984).

The incidence rate of respiratory (lung and upper respiratory tract) cancer related to the nickel industry was studied in the male population of New Caledonia over a 7-year period (1978-1984). The findings show no excess incidence of lung or upper respiratory tract (larynx, pharynx, nasal cavities) cancer cases in the population of nickel workers compared with the rest of the male population in New Caledonia. This result was corroborated by a case-control study which does not indicate any particular role of hazards specific to the nickel mining and refining industry. Our findings, which may be specific for the type of ore processed in New Caledonia, must nevertheless be confirmed by extending the study to a total of 10 years (1978-1987). The incidence rate of male respiratory cancer in New Caledonia was also compared to that of cancers of this type reported in certain regions of industrialized countries (Australia, France, U.K., USA). Such findings are very similar to those observed in New Caledonia, thereby confirming a predominant role of tobacco and alcohol consumption in a territory which, despite certain characteristics of a developing country, has life-style habits similar to those of industrialized countries.

Adult↗
PubMed1987

Effect of the O-methylation of tyrosine on the pore-forming properties of iturins.

A comparison has been made between the pore-forming properties of the antibiotic lipopeptide iturin A and a derivative methylated on the tyrosine residue which shows a restricted biological activity. It is shown that this derivative increases the ion permeability of planar lipid membranes as does iturin A. Nevertheless, the global conductance of the doped membrane is very much lower at the same lipopeptide/phospholipid ratio and the ion selectivity is inverted (PK/PCl = 6 instead of 0.6 with iturin A). The characteristics of the induced conducting pores are also rather different. This suggests an important role of the D-Tyr2 residue, present in all the compounds of the iturin family, both in the biological and in the pore-forming properties of iturin A.

Anti-Bacterial Agents↗
PubMed1987

Gene conversion in avian mesotocin and vasotocin genes: a recurrent mechanism linking two neurohypophysial precursor lineages?

Amino acid sequences of the first half of MSEL- and VLDV-neurophysins from goose and chicken have been determined. Identical substitutions in positions 17, 18, 35, 36 and 41 of both neurophysins of a given species when compared with their mammalian counterparts suggest a gene conversion between vasotocin--MSEL-neurophysin and mesotocin--VLDV-neurophysin genes. This event, which has already been observed for three mammalian species, seems recurrent and would link the evolution of the two neurohypophysial hormone precursors.

Amino Acid Sequence↗
PubMed1987

[Blood lead level in Switzerland in 1985: results of the MONICA survey].

New federal regulations regarding air pollution will soon impose catalysator equipped cars and unleaded fuel. In order to evaluate whether these measures affect the blood lead content in the Swiss population, there will be lead measurements in all three MONICA sample surveys. In the first survey, based on representative population samples, blood lead level was measured in the cantons of Vaud and Fribourg. Results based on 1774 lead measurements indicate a mean blood lead level significantly higher for males than females: 0.63 and 0.44 micromol/l. Work condition as measured by socio-professional category is only related to blood lead among males, while the living environment (community size) is only associated with female blood lead levels. Workers in agriculture and inhabitants of small communes have the lowest blood lead level. In addition, alcohol and tobacco consumption show a strong direct association with blood lead levels and are the two most important potentially confounding factors regarding the relation between blood lead levels and environmental lead pollution.

Adult↗
PubMed1987

Influence of the culture medium on the production of iturin A by Bacillus subtilis.

The production of iturin A by Bacillus subtilis was studied with respect to the composition of the culture medium. Increasing phosphate concentrations did not modify the antibiotic yield. Fructose, sucrose and mannitol were better carbon sources than glucose for antibiotic production. The nature of the nitrogen source was an important factor in the production of antibiotic. Among the amino acids which are components of iturin A, L-asparagine was the best substrate for the biosynthesis of iturin A; L-glutamine and L-serine were rather poor substrates while L-proline and D-tyrosine gave no antibiotic. Ammonium salts permitted good synthesis of antibiotic but the addition of calcium ions to the culture medium inhibited the excretion of antibiotic from the cells.

Amino Acids↗
PubMed1987

Action of iturin A, an antifungal antibiotic from Bacillus subtilis, on the yeast Saccharomyces cerevisiae: modifications of membrane permeability and lipid composition.

The action of iturin A on non-growing cells of Saccharomyces cerevisiae was tested. This antibiotic gave important modifications in the membrane permeability which permitted nucleotides, proteins, polysaccharides and lipids to escape from cells. The lipid content of cells was strongly disturbed; the level of phospholipids, essentially phosphatidylcholine, decreased while the level of fatty acids increased. A part of these fatty acids were extruded from yeast cells. The role of iturin A in these modifications was discussed.

Anti-Bacterial Agents↗
PubMed1987

Isolation and characterization of new iturins: iturin D and iturin E.

Two new antibiotics, iturin D and iturin E, were isolated from a strain of Bacillus subtilis producing iturin A. These compounds belong to the iturin group, the acid hydrolysates contained alpha-amino acids Asp3, Glu1, Pro1, Ser1, Tyr1, and a mixture of n-C14, iso-C15, anteiso-C15, iso-C16 and n-C16 beta-amino acids. They differ from iturin A by the presence of a free carboxyl group in iturin D and a carboxymethyl group in iturin E.

Antifungal Agents↗