Biomedical subjects

S Clerc

Publications and source records attributed to S Clerc.

8 recordsLinked to original sources

PubMed2005

Clusters of autochthonous hepatitis A cases in a low endemicity area.

At the University Hospital of Besançon (département of Doubs, France), an unusually high number of patients were hospitalized for hepatitis A during the 1999-2000 period, some of whom had not travelled abroad. This prompted us to conduct an investigation on a population basis and search for clusters of cases possibly related to local sources of contamination. Accordingly, case definition was restricted to autochthonous cases. During the 1999-2002 period, 45 autochthonous cases were classified as possibly originating from local environmental sources. A space-time scan statistic detected one most likely cluster (standardized incidence ratio 20.63, 95% confidence interval 10.6-37.1), consisting of 11 persons (of whom five children had attended the same swimming pool). It remained significant in a sensitivity analysis, strongly supporting the hypothesis of an environmental source of contamination. This study reveals the necessity of regular surveillance for hepatitis A and raises the issue of virological surveys of pool waters.

Adolescent↗

PubMed2000

[Socioeconomic aspects in the therapy of peritonsillar absscess].

OBJECTIVE: To determine which treatment for quinsy is the most cost-effective option. MATERIAL AND METHOD: 277 quinsies were diagnosed in 262 patients in our institution between 1.1.1991 and 31.12.1998. Median age was 29 years (1-89 years), and sex ratio was 3 males:2 females. 82 quinsy tonsillectomies (AC), 91 drainages with interval tonsillectomy (DAF) and 104 drainages of the abscess without tonsillectomy (D) were carried out. RESULTS: Median hospital stay was 3 (1-7) days for quinsy tonsillectomy, and 10 (4-18) days for drainages with interval tonsillectomy (hospital stay after drainage added to hospital stay after tonsillectomy). If interval tonsillectomy is performed as an outpatient procedure, median hospital stay decreases to 5 (2-8) days. For patients who refused tonsillectomy, median hospital stay was 3 (0-14) days. Median disability after treatment was 15 (7-30) days for quinsy tonsillectomy. For drainages with interval tonsillectomy (disability succeeding the drainage added to that following interval tonsillectomy), the median is 20 (15-52) days. For patients who refused tonsillectomy it is 6 (0-15) days. In the AC group we counted 9 late haemorrhages (11%). In the DAF group 14 patients (15%) presented a late haemorrhage; 6 patients (6%) presented a postoperative superinfection of the tonsillar fossae. DISCUSSION: On the basis of the tariffs of our institution (CHUV), and of statistical data obtained from the National Institute for Social Insurance (SUVA) with regard to the economic impact of each day of disability, the cost of the various treatment options is presented. CONCLUSION: It results from our study that in the absence of a significant difference in the rate of complications, and even considering the possibility of carrying out interval amygdalectomy on an outpatient basis, the most cost-effective treatment of peritonsillar abscess is quinsy tonsillectomy.

Adolescent↗

PubMed1999

Quantification of bias related to the extraction of DNA directly from soils.

In recent years, several protocols based on the extraction of nucleic acids directly from the soil matrix after lysis treatment have been developed for the detection of microorganisms in soil. Extraction efficiency has often been evaluated based on the recovery of a specific gene sequence from an organism inoculated into the soil. The aim of the present investigation was to improve the extraction, purification, and quantification of DNA derived from as large a portion of the soil microbial community as possible, with special emphasis placed on obtaining DNA from gram-positive bacteria, which form structures that are difficult to disrupt. Furthermore, we wanted to identify and minimize the biases related to each step in the procedure. Six soils, covering a range of pHs, clay contents, and organic matter contents, were studied. Lysis was carried out by soil grinding, sonication, thermal shocks, and chemical treatments. DNA was extracted from the indigenous microflora as well as from inoculated bacterial cells, spores, and hyphae, and the quality and quantity of the DNA were determined by gel electrophoresis and dot blot hybridization. Lysis efficiency was also estimated by microscopy and viable cell counts. Grinding increased the extracellular DNA yield compared with the yield obtained without any lysis treatment, but none of the subsequent treatments clearly increased the DNA yield. Phage lambda DNA was inoculated into the soils to mimic the fate of extracellular DNA. No more than 6% of this DNA could be recovered from the different soils. The clay content strongly influenced the recovery of DNA. The adsorption of DNA to clay particles decreased when the soil was pretreated with RNA in order to saturate the adsorption sites. We also investigated different purification techniques and optimized the PCR methods in order to develop a protocol based on hybridization of the PCR products and quantification by phosphorimaging.

Actinomycetales↗

PubMed1998

A quantitative model for using acridine orange as a transmembrane pH gradient probe.

Monitoring the acidification of the internal space of membrane vesicles by proton pumps can be achieved easily with optical probes. Transmembrane pH gradients cause a blue-shift in the absorbance spectrum and the quenching of the fluorescence of the cationic dye acridine orange. It has been postulated that these changes are caused by accumulation and aggregation of the dye inside the vesicles. We tested this hypothesis using liposomes with transmembrane concentration gradients of ammonium sulfate as model system. Fluorescence intensity of acridine orange solutions incubated with liposomes was affected by magnitude of the gradient, volume trapped by vesicles, and temperature. These experimental data were compared to a theoretical model describing the accumulation of acridine orange monomers in the vesicles according to the inside-to-outside ratio of proton concentrations, and the intravesicular formation of sandwich-like piles of acridine orange cations. This theoretical model predicted quantitatively the relationship between the transmembrane pH gradients and spectral changes of acridine orange. Therefore, adequate characterization of aggregation of dye in the lumen of biological vesicles provides the theoretical basis for using acridine orange as an optical probe to quantify transmembrane pH gradients.

Acridine Orange↗

PubMed1998

A review of available systems to investigate transfer of DNA to indigenous soil bacteria.

The deliberate or accidental release of genetically engineered microorganisms (GEMs) in the environment has led to some questions concerning microbial survival, transfer of DNA to the indigenous microflora and environmental consequences. Amongst horizontal gene transfer mechanisms, conjugation is probably the most frequent in the environment. With the aim of evaluating risks associated with environmental release of GEMs and their engineered DNA, studies of conjugative gene transfer between a donor strain and indigenous microflora have been conducted. Such studies required the development of a donor counterselection system to prevent growth of donor cells on transconjugant selective plates. This review summarizes the known and potential donor counterselection systems.

Bacteria↗

PubMed1995

Loading of amphipathic weak acids into liposomes in response to transmembrane calcium acetate gradients.

We describe a novel procedure to load amphipathic weak acid molecules into preformed liposomes. Differences in calcium acetate concentrations across the liposomal membrane induce an increase of the internal pH. This pH imbalance serves as an efficient driving force to load and accumulate weak acids (5(6)-carboxyfluorescein and nalidixic acid) inside the lipid vesicles. The mechanism of loading and the relevance of the method in drug delivery systems are discussed.

Acetates↗

PubMed1975

[Novel contribution of dynamic telethermography in the diagnosis of dysplasia and cancer of the uterine cervix (author's transl)].

At the present time when maximum information, obtained without practising an incision, on anomalies of the cervix take on the greater importance, thermivision provides novel data. Hot dysplasia was revealed to be true early cancer, cold dystrophy was near to hot subclinical cancer and "screened" in a way and picked up by routine thermovisual investigations. An elevated thermogenesis, even of a colposcopically benign lesion should maintain clinical alertness. Disagreement between the results of colposcopy, thermovision and cervico-uterine cytology, instead of leading to the rejection of these methods, must on the contrary make one look for the reasons for these divergences. D.T.T. in introducing new data, undoubtedly provides an element of uterine cervical physiology. Faced with an evident early cancer, study of the thermal emission enables one to precisely show the degree of local extension of this cancer and sometines its multifocal nature. It is an event, an approach to the physiology of malignancy. Furthermore it is remarkable to note the cooling after ionizing irradiation, rapid and complete cooling. D.T.T. is therefore called upon to take its place which is even greater as new non-mutilating therapeutic methods such as cryosurgery for example develop.

Ectropion↗

PubMedDate not supplied

[Curative radiotherapy with hope of saving the breast in operable breast cancers 403 cases with 5-year survival].

Between 1960 and 1975, 1 078 operable mammary carcinomas were treated by caesium therapy with the objective of conserving the breast. The authors analyse the indications for and results of this treatment in the 403 cases which have had more than 5 years follow up (241 cases were irradiated as primary treatment, 162 after having a simple tumorectomy). For the whole group 92 mastectomies were ultimately carried out: in 30 of them no tumour was found in the operative specimen. The tumorectomy cases, restricted to stage 1 of the UICC classification (pre 1962) -- PRV 0 IGR yielded the best results: 86 per cent 5 yeat cures with 9 out of 10 women retaining both breasts. The primary irradiation cases, all types considered, gave results comparable with those for primary radical surgery: 58 per cent 5 year cures-but 2 out of 3 women retained both breasts. By itself caesium therapy is capable of eradicating tumour in breast and axilla in half of the cases. It really amounts to a "double chance strategy"--an attempt at cure if possible with avoidance of mastectomy, this being in reserve in the event of failure.

Breast Neoplasms↗