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Biomedical subjects

H Brun

Publications and source records attributed to H Brun.

18 recordsLinked to original sources
PubMed1997

Risk factors for cholera infection in the initial phase of an epidemic in Guinea-Bissau: protection by lime juice.

Previous studies of cholera transmission have been conducted in the middle or at the end of an epidemic. Since modes of transmission could be different in different phases of an epidemic, we initiated a case-referent study immediately after the first cases had been hospitalized in a recent cholera epidemic in Guinea-Bissau in West Africa in October 1994. The cases investigated were consecutive adult patients resident in the capital of Bissau who were admitted the the National Hospital during the first two weeks of the epidemic. Referents were matched for district, gender, and age. The study showed a protective effect of using limes in the main meal (odds ratio [OR] = 0.2, 95% confidence interval [CI] = 0.1-0.3) and having soap in the house (OR = 0.3, 95% CI = 0.1-0.8). Not eating with the fingers and using water from a public standpipe were also protective. No specific source or mode of transmission was identified. Thus, cholera control programs in Africa may have to emphasize general hygienic conditions and the use of acidifiers in food preparation.

Adolescent↗
PubMed1994

Requirement of phosphatidylcholine for normal progression through the cell cycle in C3H/10T1/2 fibroblasts.

We have investigated the possible requirement of phosphatidylcholine for normal progression through the cell cycle of C3H/10T1/2 fibroblasts. Incubation of the cells in a medium with 0.5% serum synchronized the cells in the G0 stage of the cell cycle. Supplementation of the cells with 10% dialyzed and delipidated serum +/- choline resulted in normal cell division and growth for cells with choline, whereas cell division was markedly impaired in the absence of choline. Flow cytofluorometry analysis indicated that after 4 days in the absence of choline, 85% of the fibroblasts were in the G1 phase. Addition of choline resulted in synchronous synthesis of DNA with a peak occurring after 14 h. Incubation of cells with 0.5% serum had no effect on phosphatidylcholine (PC) levels in cells supplemented with 28 microM choline, but the concentration of PC was reduced from 32 to 20 nmol/10(6) cells after 1 day of incubation in the absence of choline. Supplementation with dialyzed serum, but not dialyzed and delipidated serum, allowed choline-deficient cells to replicate normally. This was attributed to the presence of lysophosphatidylcholine in dialyzed serum as this lipid, but not other lipids (e.g., phosphatidylcholine or mitogenic lipids) was able to replace the choline requirement. The choline-deficient effect was not complete; some DNA synthesis occurred in the absence of choline in the medium, and approximately 30% of the cells completed mitosis in 35 h compared to 100% in the presence of choline. The data suggest that phosphatidylcholine is required for normal progression of the cell cycle beyond the G1 phase and is unrelated to the induction of G0 to G1 transition. Choline deficiency should be a useful method for synchronizing cells in the G1 phase.

Animals↗
PubMed1992

[Deaths caused by antidepressive agents and neuroleptics. Risk groups illustrated by a forensic material].

At the Institute of Forensic Medicine, University of Oslo, legal autopsy was performed on 153 persons who died from poisoning by neuroleptics and/or antidepressants from 1986 to 1989. In one third of the cases, only neuroleptics were found at autopsy, and in little less than half of these cases the post mortem blood concentrations were considered rather low in relation to the fatal outcome. A larger proportion of alcohol abusers were found in the group with low post mortem concentrations of neuroleptics than in the rest of the material. This group contained mainly men and was further characterized by a high proportion of unintentional deaths. In the light of these facts the authors speculate whether neuroleptics represent increased risk of sudden death among alcohol abusers. The deaths due to an overdose of antidepressants were mostly suicides, and involved high post mortem blood concentrations of the drugs.

Adolescent↗
PubMed1991

Immobilization of papain on epoxy-polymers for papain-catalyzed peptide synthesis.

In this paper we describe the immobilization of papain on two commercially available carriers, VA Biosynth and Eupergit C, both in their epoxidized form. Papain can be immobilized on both polymers and shows high activity. The stability (lyophilization, storage) of the papain-VA Biosynth is very good. Even after prolonged storage (-20 degrees C) it can be reactivated to its full activity.

Catalysis↗
PubMed1991

Consequences of moderate hypoxia on red cell glycolytic metabolism in polycythemia rubra vera.

Red blood cell metabolism was studied in male patients with polycythemia rubra vera (Vaquez disease) and compared to a reference sample of 74 healthy adults. A total of seventeen enzyme activities and seventeen metabolite concentrations were determined. In addition to the modifications of the hematological parameters among the polycytemic patients significant variations were detected: a decreased content of hemoglobin in the cells; significantly decreased levels of ATP, ADP and AMP associated to an accelerated turn over of these metabolites; an acceleration of the glycolytic pathway associated with an increase of the energetic charge and levels of 2-3BPG and G1-6BP. In polycythemia rubra vera patients, the modifications of the hematological and biochemical parameters were compared to previous results obtained in high altitude residents (adaptative hypoxia) and in red cells belonging to new borns.

Adult↗
PubMed1989

Effects of oxygen-free radicals on proliferation kinetics of cultured rabbit articular chondrocytes.

It can be postulated that among the factors implicated in cartilaginous lesions, oxygen-derived free radicals seem to have a prominent part. To investigate this hypothesis, rabbit articular chondrocyte cultures have been exposed to oxygen-derived reactive species generated by the hypoxanthine-xanthine oxydase system. We observed a dose-dependent decrease of cellular growth. In order to explain this result, cell cycle progression and binucleate cell fractions have been studied. A greater number of binucleate cells and an increase in cell volume were observed. Flow cytometry analysis revealed a perturbation in cell cycle progression leading to a significant increase in the proportion of cells in G2 phase and an important augmentation in cell protein content confirmed by biochemical assays. This model shows which type of alteration can be induced by oxygen-derived free radicals in vitro. In addition, we deem this model to be useful for studying degenerative processes and for screening drugs that can scavenge oxygen-free radicals.

Animals↗
PubMed1981

Gd(-) Muret and gd(-) Colomiers, two new variants of glucose-6-phosphate dehydrogenase associated with favism.

Two males subjects are described with hitherto undescribed glucose-6-phosphate dehydrogenase (G6PD) variants. The first is of French ancestry, the second of Sicilian extraction. Each subject suffered from acute hemolytic anemia following ingestion of broad beans (Vicia fava). In both cases the hemolytic crisis occurred in a late period of life (29 and 58 years). No previous hemolytic crisis was recorded. The electrophoretic and kinetic properties of the mutant enzymes examined after purification from the red cells allowed each to be distinguished from other G6PD variants reported until now. The first variant was named Gd(-) Muret, the other Gd(-) Colomiers.

Adult↗
PubMed1979

Characterization of some erythrocyte G6PD variants by isoelectric focusing.

The existence of a microheterogeneity of glucose-6-phosphate dehydrogenase (G6PD) in human erythrocyte lysates has been previously demonstrated using isoelectric focusing (Der Kaloustian et al., 1974; Turner et al., 1975). The application of this method, modified in some aspects, to the identification of various G6PD variants led to interesting conclusions. The results reported here have been obtained from a study of four distinct molecular types: Gd(-) Mediterranean, Gd(-) Kabyle, the African Gd(+) A, and a new almost undescribed G6PD variant with severe enzyme deficiency named Gd(-) Muret.

Adolescent↗
PubMedDate not supplied

Serum cholinesterase polymorphism in France: an epidemiological survey of the deficient alleles detected by an automated micro-method.

The polymorphism of the serum cholinesterase CHE 1 was determined using an automated micro-method. The procedure developed represents an improvement of the manual method and enabled us to study more than 2400 samples obtained in 15 different geographical areas in France. Four alleles were detected: CHE1* U, A, S and F. An exceptionally high frequency of an atypical variant (CHE1*A) was observed in the central part of France (Cevennes, Limousin and Dauphiné). The populations belonging to these areas are at particular risk in case of anaesthesia.

Adult↗
PubMedDate not supplied

Cyclodextrin inclusion complexes of the central analgesic drug nefopam.

Inclusion complexes of nefopam base (NEF) with various beta-cyclodextrins (betaCDs) were investigated. All tested betaCDs increased the apparent solubility of NEF according to a Higuchi AL type plot (except betaCD: AN type plot), which indicates the formation of 1:1 stoichiometry inclusion complexes. 1H-NMR and 13C-NMR experiments showed that complexation by CDs allowed an easy separation of the R and S enantiomers. Based on spectral data obtained from the two-dimensional rotating frame nuclear Overhauser effect spectroscopy (2D-ROESY), a reasonable geometry for the complexes could be proposed implicating the insertion of the benzoxazocine ring into the wide end of the torus cavity.

Administration, Sublingual↗
PubMedDate not supplied

Improvement of a microencapsulation with aqueous core by factorial design.

Preparation of microcapsules with aqueous core and polyamide walls is influenced by several factors. We improved the stability of walls and size of capsules by simultaneous variation of four factors: total ratio of polymer, ratio of amines to acid chlorides, concentration of surfactant and speed of stirring. Use of factorial design minimizes the number of experiments and permits us to know the influence of these factors and of their interactions. By increasing the ratio of amines to acid chlorides and with a low concentration of total polymer, we obtained more stable capsules. Surfactant had a negative effect on the hardness of the polymer.

Drug Compounding↗
PubMedDate not supplied

Influence of experimental parameters on the microencapsulation of a photopolymerizable phase.

Conditions of microencapsulation by in situ polycondensation, using melamine-formaldehyde as wall material, are influenced by the chemical nature of the core to encapsulate. In our study concerning the encapsulation of a photopolymerizable phase containing an electrically charged compound, it was necessary to modify the experimental process to obtain capsules of good quality. We used the factorial design method of screening by utilization of an asymmetric matrix, according to the collapsing principle of Addleman. The advantage of this method is that it allows determination of the simultaneous influences of the 11 experimental parameters involved in this preparation. The calculation method can be applied to more than two levels for some of the factors. The continuously varying parameters were altered between two extreme levels, chosen to allow encapsulation. For discontinuous factors, such as the molecular weight of the modifying system or nature of the aminoplast, we used the commercially available compounds, respectively three and four kinds. The results of the obtained capsules were determined by comparing microphotographic pictures. With 16 experiments we found four more factors influencing quality of capsules. We also determined the most favourable levels for the other seven parameters. The results allowed us to find optimal conditions in the experimental field. We obtained capsules of a satisfactory quality for this purpose, using only minimum experimentation.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Optimization of microencapsulation of acrylic adhesives.

The preparation of microcapsules of an acrylic adhesive in a solvent medium with reticulated walls of melamine-formaldehyde was studied. In order to obtain the best experimental conditions for this process, the methodology of factorial design was used. It was found that, among the 11 tested parameters, four had an important effect on the microencapsulation: amount of wall polymer, amount and nature of the copolymer, GANTREZ, and amount of adhesive in the core. The process was optimized using a surface response methodology. A layer of microcapsules deposited on paper gave, after manual breakage, very good adhesive properties.

Acrylates↗