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Biomedical subjects

B Guerin

Publications and source records attributed to B Guerin.

At least 19 recordsLinked to original sources
PubMed1998

Failure of pristinamycin treatment in a case of pneumonia caused by a streptogramins B-type resistant pneumococcus.

We report a failure of pristinamycin treatment in a case of pneumonia caused by streptogramins B-type resistant pneumococcus. We suggest that (i) streptogramins therapy should be avoided, if a previous treatment failure has been observed with a macrolide and/or if the antibiogram shows the MLS(B) co-resistance phenotype, and (ii) beta-lactams should remain the first-line antibiotics used for treatment of pneumococcal respiratory infections.

Aged↗
PubMed1997

Unusual manifestations of hypersensitivity after a tick bite: report of two cases.

BACKGROUND: Ticks are able to transmit, through biting, various viral, parasitic, and bacterial diseases, the best known being Lyme disease due to Borrelia burgdorferi. In addition, ticks may also induce allergic reactions. OBJECTIVE: A study of immediate and delayed skin reactions are undertaken to give evidence of an IgE-dependent mechanism. METHODS: Two lumbermen reported having had skin reactions following bites by ticks. Skin prick tests and intradermal tests were performed with what was most probably Ixodes ricinus extract in one case. Specific IgE to whole body extract of wood tick were assayed by radioimmunoassay. Histological and immunohistologic examinations of skin biopsy obtained from a pruriginous skin lesion and from a delayed reaction following the intradermal test, were performed. RESULTS: One of them had positive immediate reactions to a prick test and an intradermal test with the same extract. Both patients had significant levels of wood tick-specific IgE antibody as well as elevated serum total IgE levels. Histologic examinations of a pruriginous lesion revealed lymphocytic dermal and perivascular infiltration, with evidence of CD8+ T lymphocytes and Langerhans' cells in the perivascular infiltrates. A biopsy of the place of the delayed reaction following the intradermal skin test also showed the presence of dermal and perivascular lymphocytic infiltrates. CONCLUSION: IgE-dependent allergy to Ixodes ricinus can explain allergic reactions. Standardized extracts have to be prepared with sufficient amounts of the relevant tick salivary antigens to permit diagnosis by skin and serologic tests of patients, especially lumbermen who may be allergic to Ixodes ricinus.

Adult↗
PubMed1996

Arthritis associated with monoclonal gammapathy: clinical characteristics.

We report nine cases of arthritis associated with a monoclonal gammapathy. Joint involvement was noted simultaneously or after the diagnosis of monoclonal gammapathy was made. The cases had oligoarthritis or polyarthritis mimicking rheumatoid arthritis. However, rheumatoid factor was absent in all patients, and distal interphalangeal joints were involved in two cases and sacroiliitis in one. The plasma cell dyscrasia was a multiple myeloma in two cases and monoclonal gammapathy of undetermined significance in the other patients. The light chain isotype was kappa in eight of our patients. A type I cryoglobulinaemia was associated in four cases; it was detected in the synovial fluid of two of them. We suggest that the occurrence of paraproteinaemia with chronic arthritis is more than a chance association. Moreover, a monoclonal gammapathy should be searched for in patients presenting with atypical seronegative arthritis.

Adult↗
PubMed1996

Allergic rhinitis to thuja pollen.

Allergy to pollen of Cupressaceae has been linked to pollens of Cupressus, Juniper and Cryptomeria. The authors report 2 cases of rhinitis and conjunctivitis induced by thuja, another member of the Cupressaceae family. Monosensitization to thuja pollen has been identified as the causal agent: (1) of a long-standing springtime rhinitis in 1 patient with negative skin tests and specific IgE titers to the main inhalants (specificity of the prick test and nasal provocation with the thuja extract was confirmed by a positive RAST) and (2) in a 2nd patient without former history of allergy, who consulted for conjunctivitis following acquisition of a dog; the standard battery of skin tests, and Phadiotop were all negative. After controls, only the thuja extract gave significant skin test response. The level of total IgE was low, and RAST was negative. Sensitization and pollen provocation were produced by the intermediary of the dog, carrying thuja pollens on its fur. The immunoprint and the crossed radioimmunoelectrophoresis revealed common antigenicity between cypress and thuja extracts.

Adult↗
PubMed1995

On isolated hepatocytes mitochondrial swelling induced in hypoosmotic medium does not affect the respiration rate.

In isolated hepatocytes incubated in hypoosmotic media, a large increase in the mitochondrial volume is not directly involved in the activation of respiration. Moreover, results of the quantification of the various bioenergetic parameters are not in accordance with an activation of the respiratory chain as previously proposed (Halestrap, A.P. (1989) Biochim. Biophys. Acta, 973, 355-382), but point more to an inhibition of respiration. The same respiration rate is obtained in hypoosmolar incubation media in vitro and in situ for a higher overall thermodynamic driving force over the electron transport chain.

Adenosine Diphosphate↗
PubMed1995

Systemic reactions to the Samsum ant: an IgE-mediated hypersensitivity.

BACKGROUND: In the United Arab Emirates the sting of the Pachycondyla sennaarensis ant (PSA) causes allergic reactions in certain persons. It is a common problem and is becoming a public health hazard. Up to now the diagnosis has been based only on the history, because the mechanism of the reaction was not yet established. OBJECTIVE: The aim of our study was to prepare an allergenic extract that would be used for skin tests and to prepare a reagent for specific IgE titration. Results of both skin tests and specific IgE were to be compared with the clinical history. METHODS: We studied 31 patients with anaphylactic reactions and performed clinical examinations, skin tests, and specific IgE antibody titrations. A control group of 22 subjects were also studied. RESULTS: In 30 of 31 patients (97%) findings of PSA skin tests and/or specific IgE were positive. In the control groups PSA skin test results were negative in 86% and negative for specific IgE in 68%. CONCLUSION: The study shows that the mechanism of the reaction to the sting of the PSA is a type I IgE-mediated hypersensitivity and that the diagnosis can now be confirmed by skin tests and specific IgE determination.

Adolescent↗
PubMed1994

Gender bias in the abstractness of verbs and adjectives.

Participants of both sexes were asked to write responses to sentences about members of both sexes exhibiting socially desirable or undesirable behaviors. Using Semin and Fiedler's (1988) coding scheme, I analyzed the sentences for the abstractness of the verbs and adjectives. As predicted, when the participants wrote about socially desirable behaviors performed by someone of their own gender, they used more abstract words than when they wrote about undesirable behaviors. The opposite effect was not found when the participants wrote about the other gender; possibly there was no true out-group in this study. The bias occurred even though gender was not a salient issue at the time; therefore, a more subtle bias than has been shown previously may exist.

Adult↗
PubMed1993

Relationships between age-dependent changes in the effect of almitrine on H(+)-ATPase/ATPsynthase and the pattern of membrane fatty acid composition.

The effects of almitrine on ATPase/ATPsynthase previously described in beef heart mitochondria (Rigoulet et al. (1990) Biochim. Biophys. Acta 1018, 91-97) are also observed in liver mitochondria isolated from rats older than 7 weeks. In contrast, in rats younger than 5 weeks, almitrine at the same concentration has no effect on the ATPase/ATPsynthase complex. This age-dependent action of almitrine is well correlated with age-dependent modifications of two fatty acids: linoleic and docosahexaenoic acids. The possibility of a change in H+/ATP stoichiometry of the ATPase/ATPsynthase induced by almitrine seems related to more general modifications of membrane properties during growth of the rat.

Aging↗
PubMed1992

The C-terminal region of subunit 4 (subunit b) is essential for assembly of the F0 portion of yeast mitochondrial ATP synthase.

The role of the C-terminal part of yeast ATP synthase subunit 4 (subunit b) in the assembly of the whole enzyme was studied by using nonsense mutants generated by site-directed mutagenesis. The removal of at least the last 10 amino-acid residues promoted mutants which were unable to grow with glycerol or lactate as carbon source. These mutants were devoid of subunit 4 and of another F0 subunit, the mitochondrially encoded subunit 6. The removal of the last eight amino-acid residues promoted a temperature-sensitive mutant (PVY161). At 37 degrees C this strain showed the same phenotype as above. When grown at permissive temperature (30 degrees C) with lactate as carbon source, PVY161 and the wild-type strain both displayed the same generation time and growth yield. Furthermore, the two strains showed identical cellular respiration rates at 30 degrees C and 37 degrees C. However, in vitro the ATP hydrolysis of PVY161 mitochondria exhibited a low sensitivity to F0 inhibitors, while ATP synthesis displayed the same oligomycin sensitivity as wild-type mitochondria. It is concluded that, in this mutant, the assembly of the truncated subunit 4 in PVY161 ATP synthase is thermosensitive and that, once a functional F0 is formed, it is stable. On the other hand, the removal of the last eight amino-acid residues promoted in vitro a proton leak between the site of action of oligomycin and F1.

Adenosine Triphosphatases↗
PubMed1992

The house dust mite Dermatophagoides pteronyssinus is the most important allergen on the island of Mauritius.

To determine the relative importance of mites as a cause of allergic sensitivity and asthma on the western Indian Ocean island of Mauritius, we measured specific IgE antibodies to common inhalant allergens in sera from Mauritians claiming to have allergic symptoms and we examined house dust samples for evidence of mites and their allergens. Seventy-two of the 110 sera tested (65%) contained detectable IgE antibody to at least one mite, mould or pollen allergenic extract. By far the most prevalent was antibody to one or both of the common house dust mites, Dermatophagoides pteronyssinus and Dermatophagoides farinae, being present in 67 (61%) of the 110 sera. Allergy to pollens, including the locally prevalent Bermuda grass and sugar cane, was infrequent. Antibody to a limited number of moulds was detected in 22% of the sera tested. Of 81 subjects whose clinical history was known, 60 were asthmatic, and 75% of these asthmatic individuals had IgE antibody to mites. In contrast, only 35% of the subjects with rhinitis without asthma were sensitive to mites. Different mite species, including D. pteronyssinus but not D. farinae, were identified microscopically in samples of local house dust. Mite antigen Der p I but not antigen Der f I was detected with specific monoclonal antibodies in extracts of these dust samples. On the bases of this serological and environmental survey, we conclude that our data support the hypothesis that the house dust mite D. pteronyssinus is the principal cause of allergic sensitivity and asthma in that tropical environment.

Adolescent↗
PubMed1990

Capillary leakage complicated by compartment syndrome necessitating surgery.

A single episode of systemic capillary leak syndrome is reported in a HIV-positive patient. The shock had necessitated the infusion of large amounts of fluid with concomitant diffuse swelling and weight gain leading to compartment syndrome of both legs. This required surgical relief. The initial high hematocrit (62%) and low serum protein concentration (48 g/l) with normal factor V (molecular weight above 300,000) concentrations are the hallmark of capillary leak when they are associated with hypovolemic shock. It must be emphasized that fluid resuscitation may worsen the muscle damage with ultimate compartment syndrome. Therefore, it appears reasonable to monitor muscular pressure during volume expansion in patients with capillary leak syndrome, severe shock and muscular swelling.

Adult↗
PubMed1989

The role of subunit 4, a nuclear-encoded protein of the F0 sector of yeast mitochondrial ATP synthase, in the assembly of the whole complex.

The yeast nuclear gene ATP4, encoding the ATP synthase subunit 4, was disrupted by insertion into the middle of it the selective marker URA3. Transformation of the Saccharomyces cerevisiae strain D273-10B/A/U produced a mutant unable to grow on glycerol medium. The ATP4 gene is unique since subunit 4 was not present in mutant mitochondria; the hypothetical truncated subunit 4 was never detected. ATPase was rendered oligomycin-insensitive and the F1 sector of this mutant appeared loosely bound to the membrane. Analysis of mitochondrially translated hydrophobic subunits of F0 revealed that subunits 8 and 9 were present, unlike subunit 6. This indicated a structural relationship between subunits 4 and 6 during biogenesis of F0. It therefore appears that subunit 4 (also called subunit b in beef heart and Escherichia coli ATP synthases) plays at least a structural role in the assembly of the whole complex. Disruption of the ATP4 gene also had a dramatic effect on the assembly of other mitochondrial complexes. Thus, the cytochrome oxidase activity of the mutant strain was about five times lower than that of the wild type. In addition, a high percentage of spontaneous rho- mutants was detected.

Adenosine Triphosphatases↗
PubMed1989

Thermodynamic and kinetic control of ATP synthesis in yeast mitochondria: role of delta pH.

ATP synthesis rate, measured as the variation in external Pi concentration, varied as a linear function of either delta mu H+ or delta Gpin, in such a manner that the delta Gpin/delta mu H+ ratio increased while VATP increased. We also observed a linear dependence of the flux control coefficient of the Pi carrier on delta pH. All the results presented can be explained by a relatively large delta pH drop when VATP increases.

Adenosine Diphosphate↗
PubMed1989

The yeast ATP synthase subunit 4: structure and function.

The structure of ATP synthase subunit 4 was determined by using the oligonucleotide probe procedure. This subunit is the fourth polypeptide of the complex when classifying subunits in order of decreasing molecular mass. Its relative molecular mass is 25 kDa. The ATP4 gene was isolated and sequenced. The nucleotide sequence predicts that subunit 4 is probably derived from a precursor protein 244 amino acids long. Mature subunit 4 contains 209 amino acid residues and the predicted molecular mass is 23250 kDa. Subunit 4 shows homology with the b-subunit of Escherichia coli ATP synthase and the b-subunit of beef heart mitochondrial ATP synthase. By using homologous transformation, a mutant lacking wild subunit 4 was constructed. This mutant is devoid of oxidative phosphorylation and F1 is loosely bound to the membrane. Our data are in favor of a structural relationship between subunit 4 and the mitochondrially-translated subunit 6 during biogenesis of F0.

Amino Acid Sequence↗
PubMed1988

Localization of the synthesis of very-long-chain fatty acid in mitochondria from Saccharomyces cerevisiae.

The localization of the mitochondrial elongation activities ('elongases') from Saccharomyces cerevisiae has been investigated. It was shown, using carboxyatractyloside in the incubation mixture, that synthesis of very-long-chain fatty acids probably occurred outside the matrix and, by fractionation experiments, that elongases are membrane-bound enzymes. The solubilization of the outer membrane by digitonin showed that three elongating activities are correlated with a marker of the outer membrane and not with an inner membrane marker. A further partial purification of the outer membrane showed that elongases are present in the outer membrane of mitochondria.

Acyl-Carrier Protein S-Malonyltransferase↗
PubMed1988

Redistribution of the flux-control coefficients in mitochondrial oxidative phosphorylations in the course of brain edema.

This work describes the control exerted by dicarboxylate carrier and succinate dehydrogenase activities on the oxidative phosphorylations in rabbit brain mitochondria as an edema develops. Vasogenic edema leads to an uncompetitive inhibition of succinate dehydrogenase activity and to a large decrease of oxidative phosphorylations linked to succinate utilisation. Naftidrofuryl treatment in vivo restores both a high succinate dehydrogenase activity and a normal respiratory rate. In order to quantify the control of oxidative phosphorylations by the succinate dehydrogenase step, we applied the control analysis (Kacser, H. and Burns, J.A. (1973) in Rate Control of Biological Processes (Davies, D.D., ed.), pp. 65-104, Cambridge University Press, London; Heinrich, R. and Rapoport, T.A. (1974) Eur. J. Biochem. 42, 89-95). By using two inhibitors, one (phenylsuccinate) acting only on the dicarboxylate carrier and another (malonate) acting on both the dicarboxylate carrier and the succinate dehydrogenase, a method was developed to calculate the control coefficients of these two steps. The main result is that in mitochondria isolated from normal tissue succinate dehydrogenase exerted no control, but in the course of edema this enzymatic step became a controlling one: a transition from zero to a high control coefficient (0.5) was observed from the onset of intracellular edema for the threshold value of water/dry-weight tissue of 4.6.

Animals↗