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Biomedical subjects

B Guérin

Publications and source records attributed to B Guérin.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Clinical and therapeutic aspects of hepatic amebiasis in Cambodia].

Amoebic liver abscess is a common disease in developing countries. Although therapy is now perfectly standardized, errors and inaccuracies are frequent in daily practice. A study was performed at the Calmette Hospital in Phnom Penh (Cambodia) to evaluate and improve this situation. Diagnostic criteria and the outcome of treatment with oral or parenteral metronidazole were analyzed in 38 patients presenting amoebic liver abscess. Hepatalgia was observed in 100% of cases. Hyperleukocytosis and enhancement of the sedimentation rate occurred in 95% of cases. Diagnosis was confirmed by ultrasonography. Serodiagnosis, given its high cost, was not indispensable. Metronidazole was of comparable effectiveness and tolerance (90%) whether administered by the oral or parenteral route. The parenteral route should be used only for patents presenting digestive intolerance. Drainage of the abscess is necessary in cases characterized by immediate complications, abscesses with diameters greater than 120 mm and absence of improvement after 5 days of treatment.

Adult↗
PubMed1995

[The use of gene amplification for the detection of the Aujeszky's disease virus in the sperm of boars].

The aim of the present study was to specify the experimental conditions for the use of the polymerase chain reaction (PCR) in the detection of the pseudorabies virus in boar semen. Boar semen was artificially contaminated by Aujeszky's disease virus and submitted to the PCR. The seminal plasma fraction of the semen was found inhibitory for PCR. An incubation of the samples with proteinase K followed by an extraction of the viral DNA on a glass matrix was shown to be able to remove the inhibition. The method was simple, rapid and allowed the detection of around 370 viral DNA sequences per microliter of sample. The detection of the amplified DNA by a specific enzymatically labelled probe could improve the sensitivity of the method.

Animals↗
PubMed1995

Polyarthritis in HTLV-1-infected patients. A review of 17 cases.

A retrospective study was conducted in Martinique to identify patients with polyarthritis and positive serologic tests for the human T-cell lymphotropic virus Type I (HTLV-1). Patients with metabolic or bacterial causes of polyarthritis were excluded. We found 17 cases of HTLV-1-positive polyarthritis (6.7% of the total of polyarthritis patients followed in our department); there were 14 females and three males, and all the patients were West-Indian blacks. Mean age at diagnosis was 50 years. Five patients also had tropical spastic paraparesis. The polyarthritis was the inaugural manifestation of T-cell leukemia in one patient. Four patients had received blood transfusions. Fever, myalgia, and/or skin lesions were present at onset of the polyarthritis in seven cases. All 17 patients had peripheral, bilateral, symmetric polyarthritis; the most commonly involved sites were the hands (17/17) and knees (14/17). Three patients had rheumatoid factor and five had antinuclear antibody. Ten patients met at least four American Rheumatism Association criteria for rheumatoid arthritis; they accounted for 6.7% (10/150) of all polyarthritis patients managed in the same hospital department during the same period. We compared these ten patients with 20 HTLV-1-negative rheumatoid arthritis patients matched on gender, ethnic origin, and disease duration. There were no significant differences between the two groups for any of the parameters studied.

Adult↗
PubMed1994

ATP-induced unspecific channel in yeast mitochondria.

ATP induced swelling of isolated yeast mitochondria suspended in an isoosmotic solution of potassium gluconate. Valinomycin stimulated the swelling rate, indicating that K+ influx in the presence of ATP is rate-controlling. This swelling was inhibited by ADP, phosphate (probably acting on the external face of the inner membrane), and Mg2+, which forms a complex with ATP. ATP-induced swelling did not require working F0-F1-ATPase since it was not inhibited by oligomycin and uncoupler. CTP and GTP also induced a swelling. ATP also induced mitochondrial swelling in potassium glutamate, chloride, and acetate but not in phosphate solutions. Sodium, but not ammonium, can replace potassium ion. It is probable that the ATP-channel opening also necessitates an electrogenic cation influx. Respiration also induced swelling of mitochondria suspended in isoosmotic potassium gluconate solution. ATP- or respiration-induced swelling were inhibited equally by N,N'-dicyclohexylcarbodiimide, propranolol, and Zn2+ but not by quinine; all these drugs inhibit the H+/K+ exchange. It was concluded that this unspecific channel is not open under conditions used to measure oxidative phosphorylation. Its physiological role remains unknown.

Acetates↗
PubMed1994

Mutation in the hydrophobic domain of ATP synthase subunit 4 (subunit b) of yeast mitochondria disturbs coupling between proton translocation and catalysis.

We introduced mutations to test the function of the hydrophobic sector of subunit 4 from Saccharomyces cerevisiae ATP synthase. Mutations were introduced at the chromosomic locus by homologous transformation of a strain disrupted in the ATP4 gene. The strain carrying the replacement Leu68-Val69-->Arg-Glu did not grow at 37 degrees C owing to a lack of assembly of F1 and Fo sectors at this temperature. The mutant strain grew slowly by oxidative phosphorylation at 28 degrees C with a growth yield 30% lower than the wild type. Analysis of the mutant strain showed a homogeneous population of altered ATP synthase with an energy coupling impairment. The mutant strain was oligomycin-resistant since the I50 value of oligomycin inhibition of ATPase and ATP synthase activities was 2-3-fold higher than that of the wild type, thus showing an alteration of the target to oligomycin. The level of phosphorylation or ATP induced a proton-dissipating pathway through Fo, which was insensitive to oligomycin but was sensitive to dicyclohexylcarbodiimide, thus suggesting an alteration in the regulation of ATP synthase proton permeability by the catalytic sector. From these results, we propose that the dicyclohexylcarbodiimide inhibition site is located upstream of the oligomycin inhibition site when considering the proton flux occurring during ATP synthesis.

Base Sequence↗
PubMed1994

Mechanistic stoichiometry of yeast mitochondrial oxidative phosphorylation.

This study investigates the relationships between the efficiency of oxidative phosphorylation (ATP/O) and respiratory flux in yeast mitochondria. To manipulate the electron flux through the respiratory chain, different substrates leading to NAD(P)H were used. By testing the effect of ADP either on respiratory rate in the presence or absence of oligomycin or on the level of NAD(P)H, on one hand, and the effects of uncouplers on respiration, on the other, we distinguished several categories of substrates: those for which the low respiration rate was mainly controlled by dehydrogenase activities and others for which the respiration was high and controlled downstream from the dehydrogenases. By using these different substrates, we observed that the ATP/O ratio decreased irrespective of the proton-motive force when the electron flux increased, unlike the situation when the respiratory rate was modulated by addition of the respiratory inhibitor. This result suggests that the oxidative phosphorylation efficiency depends on the value of the flux crossing the proton pumps. This relationship between efficiency (ATP/O) and electron flux was linked to a main control upstream from the respiratory chain. Such changes in the ATP/O ratio at least involved changes in the stoichiometry (H+/2e-) of the respiratory chain. Indeed, in non-phosphorylating mitochondria, the ratio of stoichiometries at site 2+3 over site 3 varied according to the proton-motive force. This cannot be explained by a variation in proton leak alone but involved both (i) a variable stoichiometry (H+/2e-) in relation to the electron flux value and (ii) different relationships between the variation in stoichiometry and the flux value at each coupling site.

Adenosine Triphosphate↗
PubMed1994

Temperature dependence of the coupling efficiency of rat liver oxidative phosphorylation: role of adenine nucleotide translocator.

We have reinvestigated the temperature dependence of the coupling efficiency of energy conversion in isolated rat liver mitochondria. We observed that respiratory control increased with temperature. Moreover, in the same conditions, the ATP/O ratio increased. The measurement of the control coefficients of adenine nucleotide translocator on respiratory and ATP synthesis rates showed that at 28 degrees C, this translocator exerted the same control (about 0.5) on both fluxes. At 4 degrees C, it no longer exerted control on respiratory flux when its control on ATP synthesis flux came close to 1. In addition, ATP/O ratio values and control coefficients on ATP synthesis flux were bound by a unique linear relationship irrespective of temperature. In conclusion, the decrease in ATP/O ratio with temperature is a direct consequence of an increase in the kinetic control exerted by the adenine nucleotide translocator on ATP synthesis.

Adenosine Diphosphate↗
PubMed1994

Selection of European Union standard reference sera for use in the serological diagnosis of infectious bovine rhinotracheitis.

A study, consisting of three trials, was undertaken in order to find standard reference sera for use in serological diagnostic procedures for infectious bovine rhinotracheitis (IBR) in the European Union (EU). A total of forty-nine laboratories participated in the trials, in which panels of positive, weak positive, and negative candidate sera were tested blind by neutralisation, indirect and blocking enzyme-linked immunosorbent assay, indirect immunofluorescence and passive haemagglutination. A serum which scored positive in all tests in all laboratories was selected as a strong positive standard serum. The chosen negative standard serum gave negative results in virtually all tests. A 1/36 dilution of a positive serum was chosen as the weak positive standard serum and only very sensitive techniques were able to score it positive. Three EU reference sera are now available for the standardisation of serological tests for IBR.

Animals↗
PubMed1994

[Unexpected outcome of a twin transfusion syndrome. A case report].

A monochorial biamniotic twin pregnancy was uneventful until 24-weeks amenorrhoea when severe donor-recipient transfusion syndrome occurred. Unexpectedly, the situation stabilised spontaneously with regression of amniotic fluid anomalies. Pathology examination of the placenta revealed that a central placental cotyledon had undergone ischaemic necrosis which could have led to interruption of fetal-fetal transfusion at about 23 weeks amenorrhoea.

Adult↗
PubMed1994

[Purification and standardization of allergens].

Allergen preparations cannot be compared with any other class of drugs. Their compositions are as varied as the raw materials that induce sensitisation and their biological activities are as variable as the individual immunological profiles of patients. They are obtained by extraction and therefore very dependent on the methods used, based on known principles. The multiplicity of the allergens they contain have mostly not yet been characterised and this does not allow individual measurement. Standardisation of the allergen preparations is done mostly by comparison of their overall activity with that of a reference preparation. This is expressed in arbitrary units or in units of biological activity determined on representative mean populations of allergic subjects.

Allergens↗
PubMed1994

[Environment and acari].

Perennial domestic allergies are the expression of an illness from urban civilization. The Pyroglyphidae mites, also called epithelium phages because they feed mostly on human skin scales and with bed as their ecological niches, bear the major responsibility. They may also produce sensitization to others, known as storage mites, which develop naturally in the food stores found in barn and silos as well as in badly maintained kitchen cupboards. These mites develop quickly when they find favourable atmospheric conditions (25/27 degrees C--70/75% rH) and a good source of food. To prevent their multiplication strict domestic hygiene must be combined with protection of bedding by covers and with the use of sufficient amounts of acaricides.

Allergens↗
PubMed1993

Interactions between glucose metabolism and oxidative phosphorylations on respiratory-competent Saccharomyces cerevisiae cells.

The purpose of this work was to analyze the interactions between oxidative phosphorylations and glucose metabolism on yeast cells aerobically grown on lactate as carbon source and incubated in a resting cell medium. On such respiratory-competent yeast cells, four different metabolic steady states have particularly been studied: (a) glucose feeding under anaerobiosis, (b) ethanol supply under aerobiosis, (c) glucose supply under aerobiosis and (d) glucose plus ethanol under aerobiosis. For each condition, we measured: (a) the cellular ATP/ADP ratio and NADH content sustained under these conditions, (b) the glucose consumption rate (glucose conditions) and the respiratory rate (aerobic conditions). Under aerobic conditions, when ethanol is used as substrate, the ATP/ADP ratio and NADH level are very high as compared with glucose feeding. However, the rate of oxygen consumption is similar under both conditions. The main observation is a large increase in the respiratory rate when both glucose and ethanol are added. This increase corresponds to an ATP/ADP ratio and a NADH level lower than those observed with ethanol but higher than those with glucose. Therefore the response of the respiratory rate to the ATP/ADP ratio depends on the redox potential. We studied the way in which the ATP-consuming activity was increased under glucose+ethanol conditions. By NMR experiments, it appears that neither the futile cycle at the level of the phosphofructo-1-kinase/fructo-1,6-bisphosphatase couple nor the synthesis of carbohydrate stores could account for the increase in oxidative phosphorylation. However, it is shown that, in the presence of glucose+ethanol, ATP consumption is strongly stimulated. It is hypothesized that this consumption is essentially due to the combination of the well-known plasma membrane proton-ATPase activation by glucose and the high phosphate potential due to oxidative ethanol metabolism. While it is well documented that oxidative phosphorylations inhibit the glycolytic flux, i.e. the Pasteur effect, we clearly show in this work that the glycolytic pathway limits the ability of mitochondria to maintain a cellular phosphate potential.

Adenosine Diphosphate↗
PubMed1993

ATP synthase of yeast mitochondria. Isolation and disruption of the ATP epsilon gene.

The nuclear gene encoding the subunit epsilon of the catalytic sector F1 of the yeast Saccharomyces cerevisiae ATP synthase was cloned and sequenced. Degenerated oligonucleotide primers were constructed from primary structure data. A part of the ATP epsilon gene was amplified by polymerase chain reaction from yeast genomic DNA. From the amplified DNA sequence a nondegenerated oligonucleotide probe was constructed and used for isolating a 2040-base pair EcoRI fragment bearing the whole gene. A 186-base pair open reading frame encoding a 62-amino acid polypeptide is described. The deduced amino acid sequence was one amino acid longer than the mature protein. A null mutant was constructed. The mutant strain was unable to grow on glycerol medium. The mutant mitochondria had no detectable oligomycin-sensitive ATPase activity. The catalytic sector appeared unstable during purification but F0-subunits were still bound to F1. The mutation promoted a highly oligomycin-sensitive uncoupling of the mitochondrial respiration rate.

Amino Acid Sequence↗
PubMed1993

Distribution of BHV1 in fractions of semen from a naturally infected bull.

The aim of the present study was to investigate the distribution of BHV1 (Bovine Herpesvirus 1) in the semen from a naturally infected bull and more particularly, to determine if there were viral particles associated with sperm that could interfere with in-vivo or in-vitro fertilization. Frozen semen from a single ejaculate that had been previously identified as being contaminated with BHV1 was used. The contents of 12 ministraws were mixed. Two aliquotes served as controls, the first was held at 0 degrees C in ice water while the second was held at 4 degrees C in the centrifuge during the procedure. The remaining semen was separated into seminal plasma and sperm cell fractions by centrifugation. The seminal plasma was kept at 0 degrees C until viral titration. The pellet was treated by 10 consecutive washes in PBS and by a trypsin treatment after the fifth wash. Subsequently, the last pellet was macerated to break the cell membranes. Aliquotes for viral titration were taken from all washing fluids, from pellets after the fourth, sixth and tenth washes, and from the last crushed pellet. These aliquotes were kept in ice water until titration. The virus was titrated on secondary cell cultures of fetal calf kidney. The titers were 4.3, 4.2 and 4.4 log TCID50/ml, respectively, in the 2 controls and the seminal plasma. Titers declined from 3.8 log to 0 from the first to the tenth wash. The titer was 2.2 log in the resuspended pellet of sperm cell fraction prior to trypsin treatment. No virus was detected in the sixth pellet, the tenth one or from the crushed cells. It was concluded that a significant proportion of the BHV1 particles was associated with the sperm cells. Ten washes and a trypsin treatment could remove the adsorbed virus. No viral particles were detected within the sperm cells.

Journal Article↗
PubMed1993

[Evaluation of the epidemic caused by the human immunodeficiency virus in Cambodia].

The infection by the human immunodeficiency virus is in the process of expanding to a dramatical level in South East Asia. At the moment, the few available datas on Cambodia are increasingly worrying, with a rate of seropositivity of prostitutes higher than 9% in 1992 and a clear progression of the rate of seropositivity of blood donors: 1.3% by the second quarter of 1993.

Cambodia↗
PubMed1993

A European comparative study of serological methods for the diagnosis of infectious bovine rhinotracheitis.

A comparison is made of serological diagnostic procedures used for infectious bovine rhinotracheitis in the European Community. A panel of 65 sera, including positive, doubtful, negative and diluted samples was dispatched to nine different European laboratories and tested by neutralisation, enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence and passive haemagglutination, according to the methods used in each laboratory. The results showed good agreement between the various tests for positive and negative sera. However, considerable variability between tests was noted in the "doubtful" category of sera. The highest test sensitivity, as judged by the detection limit for samples serially diluted in negative serum, was found with the blocking ELISAs. A need was identified for international standard reference sera to be made available.

Animals↗