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M Frechet

Publications and source records attributed to M Frechet.

4 recordsLinked to original sources

Overexpression of DNA polymerase beta: a genomic instability enhancer process.

DNA polymerase beta (Pol beta) is the most inaccurate of the six DNA polymerases found in mammalian cells. In a normal situation, it is expressed at a constant low level and its role is believed to be restricted to repair synthesis in the base excision repair pathway participating to the genome stability. However, excess of Pol beta, found in some human tumors, could confer an increase in spontaneous mutagenesis and result in a highly mutagenic tolerance phenotype toward bifunctional DNA cross-linking anticancer drugs. Here, we present a hypothesis on the mechanisms used by Pol beta to be a genetic instability enhancer through its overexpression. We hypothesize that an excess of Pol beta perturbs the well-defined specific functions of DNA polymerases developed by the cell and propose Pol beta-mediated gap fillings during DNA transactions like repair, replication, or recombination pathways as key processes to introduce illegitimate deoxyribonucleotides or mutagenic base analogs like those produced by intracellular oxidative processes. These mechanisms may predominate during cellular nonproliferative phases in the absence of DNA replication.

DNA Polymerase beta↗

Community acquired pneumonia in adults: a study comparing clinical features and outcome in Africa (Republic of Guinea) and Europe (France).

BACKGROUND: Community acquired pneumonia is the most common cause of death from infectious disease both in western and developing countries. A study was carried out in Conakry, Republic of Guinea and Tours, France in order to compare signs, symptoms, severity of illness, risk factors, and clinical outcome of community acquired pneumonia in adult patients admitted to hospital. METHODS: The study was performed in the cities of Conakry and Tours over the same one year period. Patients with nosocomial pneumonia, tuberculosis, and those who were HIV positive were excluded. Data were recorded on the same forms in both centres. A severity score was calculated according to American Thoracic Society criteria. Follow up was evaluated at days 2, 7 and 15. RESULTS: A total of 333 patients (218 from Conakry, 115 from Tours) were included in the study with a diagnosis of community acquired pneumonia, with or without lung abscess or pleural effusion. Mean age was higher and pre-existing illness rate, dehydration, agitation, and stupor were more frequent in patients in Tours. Respiration rates of > 30 breaths/min and the incidence of crackles were identical in the two centres. Fever above 39 degrees C, initial shock, chest pain, and herpes were significantly more frequent in Conakry. Initial chest radiographic abnormalities were similar in the two groups, ranging from unilateral pleuropulmonary involvement (89% and 83% in Conakry and Tours, respectively) to diffuse patchy parenchymal disease. Parapneumonic effusion was present in 17% and 16% of the patients of Conakry and Tours, respectively. Pneumonia was considered to be severe in 33% and 42% of the patients, respectively. In Conakry first line antibiotic therapy was penicillin alone (2 million units a day) for 197 patients (90%) and second line antibiotic therapy was prescribed for 25 patients (12%). In Tours first line therapy consisted of a single antibiotic (amoxicillin, third generation cephalosporins) for 65 patients (57%) and second line antibiotic therapy was prescribed for 55 patients (48%). The clinical outcome was similar in Conakry and Tours: 88% and 85% of patients, respectively, were afebrile or clinically cured at day 15. The mortality rate was similar (6% and 8%, respectively). CONCLUSIONS: The problems encountered in the management of community acquired pneumonia are quite different in western and developing countries. This study shows that low doses of penicillin can cure 90% of African patients with pneumonia as effectively as more aggregative treatments in European patients who are both older and have greater comorbidity. Although pneumococci with reduced penicillin sensitivity occur in western countries, this does not seem to be the case in black Africa. For these reasons, low doses of penicillin or amoxicillin remain good first line treatment.

Adult↗