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Biomedical subjects

D Thouvenot

Publications and source records attributed to D Thouvenot.

68 records · Page 4Linked to original sources
PubMed1985

Role of Penicillic Acid in the Phytotoxicity of Penicillium cyclopium and Penicillium canescens to the Germination of Corn Seeds.

Penicillium cyclopium and Penicillium canescens cultures inhibited the germination of corn. The phytotoxic compound was isolated by solvent extraction and thin-layer chromatography on silica gel. The phytotoxin was identified as penicillic acid by mass spectrometry, nuclear magnetic resonance, and infrared spectroscopy. Gas-liquid chromatography on a capillary glass column separated the two epimeric forms of penicillic acid. The maximum production of penicillic acid was obtained with P. cyclopium cultures grown at 25 degrees C. The phytotoxicity of penicillic acid was manifested by its ability to alter the germination of corn. The percent inhibition of germination was directly proportional to the logarithm of the penicillic acid concentration. Growth of the main root was reduced 50% by concentrations of 500 mug/ml.

Journal Article↗
PubMed1984

[Evaluation of the incidence of serological cross reactions between Legionella and Mycoplasma or Chlamydia].

Because of the possible serological cross reactions frequently described in the literature between L. pneumophila and M. pneumoniae or between L. pneumophila and Chlamydia, we decided to determine their frequency with our sera and our own methods. The anti M. pneumoniae and Chlamydia antibodies were researched in 162 sera samples from 46 cases of legionellosis serologically diagnosed and in 51 sera from 26 hyperimmunised rabbits. Conversely, anti L. pneumophila antibodies were researched in 165 sera from mycoplasmosis (61) or chlamydiosis (25 cases). None of the sera from mycoplasmosis or chlamydiosis tested by IFA and MA had antilegionella antibodies. None of the rabbits' sera hyperimmunised with Legionella had anti M. pneumoniae or Chlamydia antibodies. On the contrary, by complement fixation and IFA, out of the 46 cases of legionellosis under study, 6 showed a seroconversion in M. pneumoniae and 2 in Chlamydia. The Ig class determination did not show IgM titers in 7 of these 8 sera. The mechanisms of these cross reactions are discussed: antigens and methods used, booster effect during legionellosis, concurrent mycoplasmosis or chlamydiosis.

Agglutination Tests↗
PubMed1983

Radioimmunoassay for zearalenone and zearalanol in human serum: production, properties, and use of porcine antibodies.

To produce antigens susceptible to raise antibodies for resorcylic acid lactones, the 6'-carboxymethyloxime derivatives of zearalenone and zearalanone were bound to bovine serum albumin. Pigs could be immunized by using these antigens, the best titer in antibodies being obtained with the zearalenone antigen. The porcine antibodies were specific for the resorcylic acid lactones of structural resemblance with zearalenone. This specificity made the antibodies usable for a radioimmunoassay of zearalenone and zearalanol, which may be found in human and animal sera. The range of the assay was between 0.25 and 10 ng. The limit of detection was 5 ppb (5 ng/ml) in human serum.

Animals↗
PubMed1981

Transformations of zearalenone and alpha-zearalanol by homogenates of human prostate glands.

The present study applied high-pressure liquid chromatography, gas chromatography/mass spectrometry and crystallizations to constant specific activity for identification of the radiometabolites of tritiated zearalenone and alpha-zearalanol in homogenates of human prostate glands. Radiolabelled zearalenone or alpha-zearalanol (6.3 microM) was incubated for 30 min at 37 degrees C with prostatic homogenate in 5 ml 0.067 M phosphate buffer (pH 7.4) containing 0.5 mM oxidized or reduced NAD or NADP. Reduction of zearalenone occurred only with NADPH while oxidation of alpha-zearalanol was favoured both by NADP+ and NAD+. Separation of the substrates from their metabolites by high-pressure liquid chromatography showed the radioactivity of the metabolite of zearalenone to be associated with the alpha-zearalenol carrier while that of the alpha-zearalanol metabolite was found with the zearalanone carrier. Crystallizations to constant specific activity after isotopic dilution and gas chromatography/mass spectrometry confirmed the identity and the radiochemical purity of the alpha-zearalanol substrate and of its zearalanone metabolite. In contrast, the poor radiochemical purity of the zearalenone substrate and of its alpha-zearalenol metabolite was explained by the presence of large quantities of cis-isomer contaminants which were identified by gas chromatography/mass spectrometry. Formation of the cis-isomer of zearalenone was shown to occur spontaneously in incubations with boiled homogenates. The other stereospecific reductions or oxidations of the substrates were due to the prostatic enzymes which could be those involved in the C19-steroid hormone metabolism.

Biotransformation↗
PubMed1978

Poliomyelitis survey in Middle-East countries.

The poliomyelitis survey was started in 1976 in Bahrain and Kuwait. For each paralytic case, diagnosis was done by virus isolation, neutralizing antibody titration and specific IgM characterization. More than 90% of the infants who were ill were less than 2 years old. In Bahrain, 17 paralytic cases in 1976 and 12 in 1977 occurred between January and July (annual incidence was respectively 7.7 and 5.4/100,000). The first epidemic was due to poliovirus type 2, the second one to poliovirus type1. From 29 cases, 13 occurred in vaccinated infants of which 9 received 3 or 4 oral vaccine doses. For 3 infants, paralysis occurred less than one month after vaccination. All the isolates were wild polioviruses (rct). In Kuwait, 119 cases were examined, and of them, 57 occurred between August 76 and May 77 (incidence 5.7/100,000). Poliovirus type 1 was responsible for 61% of cases, type 2 for 5% and type 3 for 12%. From October 1976 to December 1977, 350 stools samples were collected from contacts: 19% of them carried poliovirus (12% type 1, 1% type 2 and 6% type 3). All the viruses isolated from both paralytic cases and contacts were wild strains (rct). Of 119 cases, 35 occurred in vaccinated infants from which 4 had received 3 or 4 oral vaccine doses. For 11 infants paralysis occurred less than one month after vaccination. The virus spread was evaluated (i) just before vaccination in 337 infants or children from June to December 76: 8% carried poliovirus Sabin-like strains (and 18% non polioviruses), and (ii) one month after vaccination in 75 infants: 37% carried poliovirus Sabin-like strains.

Adolescent↗
PubMed1974

Comparison of the immune response of the rabbit to virulent and attenuated strains of type 1 poliovirus.

Rabbits were immunized with the attenuated LSc, 2a(1)b or the virulent Mahoney strain of type 1 poliovirus, or with a partially purified preparation of the latter. It was found that the animals responded in a heterogeneous manner to antigens with a homogeneous virion population, such as LSc,2a(1)b and, to a lesser extent, the partially purified Mahoney antigen. This heterogeneous immune response permits the preparation of specific antisera for intratypic serodifferentiation tests. However, the unpurified Mahoney strain, which has a heterogeneous virion population, induced a homogeneous immune response; all the antisera had a wide spectrum of antibodies and could not distinguish the wild from the attenuated strain. The differentiation capacity of the specific antisera was found to be linked to either the IgM or the IgG. The possible implications of these findings for human vaccination against poliomyelitis are discussed.

Analysis of Variance↗
PubMedDate not supplied

In vitro toxicity of trichothecenes on human haematopoietic progenitors.

The culture of human haematopoietic progenitors, Colony-Forming-Unit Granulocyte and Macrophage (CFU-GM), has been performed in the presence of four trichothecenes, T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS), and deoxynivalenol (DON). Our results showed that trichothecenes were cytotoxic for human haematopoietic progenitors. This work and the analysis of results described in the literature allowed us to propose that the haematologic lesions observed during human intoxication could be due to a destruction of haematopoietic progenitors such as granulocytic and macrophage colony-forming cells.

Cell Survival↗
PubMedDate not supplied

In vitro toxicity of trichothecenes on rat haematopoietic progenitors.

The fusarial toxicosis induced by trichothecenes is characterized by common syndromes such as vomiting, inflammation, haemorrhages, diarrhoea and haematological changes. Subchronic ingestion of trichothecenes causes a decrease in circulating white cells. This leukopenic change of animals is reported as a characteristic feature in the best known human disorder: Alimentary Toxic Aleukia (ATA). The aim of the present study was to evaluate whether the haematologic disorders imputed to trichothecenes were a result of myelotoxicity by investigating in an in vitro model. Rat haematopoietic progenitors, Colony Forming Units-Granulocytes and Macrophages (CFU-GM), were cultured in the presence of several concentrations of four trichothecenes; T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS) and deoxynivalenol (DON). All these trichothecenes were cytotoxic to rat haematopoietic progenitor cells. It is concluded that haematological disorders observed during trichothecene intoxication of animals are caused by the destruction of haematopoietic progenitors such as CFU-GM cells.

Animals↗
PubMedDate not supplied

[Contribution of the laboratory in case of resistance to acyclovir of herpes simplex and varicella zoster virus].

Herpes simplex virus (HSV) and varicella zoster virus (VZV) are susceptible to acyclovir which inhibits viral replication through two viral enzymes, thymidine kinase (TK) and DNA polymerase. Resistance may occur, it is a rare phenomenon among immunocompetent patients but resistance is more frequent and may be associated with serious complications among immunocompromised patients. Virological survey of these at risk patients is needed to detect resistant virus as soon as possible through phenotypic tests performed on virus isolated on cell cultures. Resistant virus may also be genetically characterised by detection of mutations within TK and DNA polymerase genes. Pharmacological parameters also have to be taken into consideration and a determination of acyclovir blood concentration should be performed in case of unexplained therapeutic failure. Improvement of immune system, when possible, may resolve these infections. Alternative treatments using drugs such as foscarnet or cidofovir which have a different mechanism of action compared to acyclovir, are recommended but these molecules are often more toxic than acyclovir.

Acyclovir↗