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Biomedical subjects

M Bertin

Publications and source records attributed to M Bertin.

At least 19 recordsLinked to original sources
PubMed2006

The role of an absolutely conserved tryptophan residue in octamer formation and stability in mitochondrial creatine kinases.

In most organisms, mitochondrial creatine kinase (MtCK) is present as dimers and octamers with the latter predominating under physiological conditions. An absolutely conserved tryptophan residue (Trp-264 in chicken sarcomeric MtCK) appears to play a key role in octamer stability. Recently, it has been shown that the sponge Tethya aurantia, a member of the most ancient group of living multi-cellular animals, expresses an obligate, dimeric MtCK that lacks this absolutely conserved tryptophan residue, instead possessing a tyrosine in this position. In the present study we confirm that the absolutely conserved tryptophan residue is lacking in other sponge MtCKs where it is instead substituted by histidine or asparagine. Site directed mutations of the Trp-264 in expression constructs of chicken sarcomeric MtCK and the octameric MtCK from the marine worm Chaetopterus destabilized the octameric quaternary structure producing only dimers. A Tyr-->Trp mutation in an expression construct of the Tethya MtCK construct failed to produce octamerization; Tyr-->His and Tyr-->Asn mutations also yielded dimers. These results, in conjunction with analysis of homology models of Chaetopterus and Tethya MtCKs, strongly support the view that while the absolutely conserved tryptophan residue is important in octamer stability, octamer formation involves a complex suite of interactions between a variety of residues.

Amino Acid Sequence↗
PubMed2004

Relationship between glycopeptide use and decreased susceptibility to teicoplanin in isolates of coagulase-negative staphylococci.

To investigate the relationship between glycopeptide use and decreased susceptibility to teicoplanin in coagulase-negative staphylococci (CNS) isolates, data on teicoplanin susceptibility and glycopeptide use from existing microbiology laboratory and pharmacy databases were collected for the period between July 2000 and March 2001. Pooled data for the entire study period were first used to analyse associations. Univariate analysis showed that the incidence of CNS with decreased susceptibility to teicoplanin was significantly correlated with the use of glycopetides, particularly with vancomycin use. This association was confirmed by multivariate analysis. This study suggests that variations in antimicrobial resistance are related to variations in antimicrobial use in the model of CNS with decreased susceptibility to teicoplanin, thus confirming the usefulness of restricting antimicrobial prescribing as a means of controlling resistance.

Anti-Bacterial Agents↗
PubMed2003

Modelling the usefulness of a dedicated cohort facility to prevent the dissemination of MRSA.

The aim of this retrospective study was to determine whether or not a surgical dedicated cohort facility, mainly dedicated to the care of orthopaedic patients, can control the risk of infection caused by methicillin-resistant Staphylococcus aureus (MRSA). We tested this hypothesis on the orthopaedic surgery ward of a university-affiliated public hospital with 1228 beds by determining whether there was a significant correlation between the colonization pressure exerted by MRSA and the number of cases of acquired MRSA. This was then used as a tool to predict the number of patients contaminated with MRSA in hospitals with and without dedicated cohort facilities. We found that the relative risk of MRSA acquisition increased with the colonization pressure exerted by MRSA imported cases. This statistical model enabled us to predict that the risk of MRSA acquisition would increase by 160% per year in the absence of a dedicated cohort facility. We conclude that these units are useful to control the spread of MRSA in hospitals.

Cohort Studies↗
PubMed2002

The incidence of invasive aspergillosis among solid organ transplant recipients and implications for prophylaxis in lung transplants.

BACKGROUND: Invasive aspergillosis (IA) is associated with significant morbidity and mortality in solid organ transplant recipients but data on the incidence rates stratified by type of solid organ are limited. OBJECTIVE: To describe the attack rates and incidence of IA in solid organ transplant recipients, and the impact of universal Aspergillus prophylaxis (aerosolized amphotericin B or oral itraconazole) in lung transplant recipients. PATIENTS: The 2,046 patients who received solid organ transplants at the Cleveland Clinic Foundation from January 1990 through 1999 were studied. METHODS: Cases were ascertained through computerized records of microbiology, cytology, and pathology reports. Definite IA was defined as a positive culture and pathology showing septate hyphae. Probable IA was clinical disease and either a positive culture or histopathology. Disseminated IA was defined as involvement of two or more noncontiguous anatomic sites. RESULTS: We identified 33 cases of IA (28% disseminated) in 2,046 patients (attack rate = 1.6%) for an incidence of 4.8 cases per 1,000 patient-years (33 cases/6,813 pt-years). Both the attack and the incidence rates were significantly higher for lung transplant recipients vs. other transplant recipients: lung 12.8% (24 cases/188 patients) or 40.5 cases/1,000-pt year vs. heart 0.4% (3/686) or 1.4 per 1,000-pt year vs. liver 0.7% (3/439) or 2.1 per 1,000-pt year vs. renal 0.4% (3/733) or 1.2 per 1,000-pt year (P < 0.01). The incidence of IA was highest during the first year after transplantation for all categories, but cases occurred after the first year of transplantation only in lung transplant recipients. The attack rate of IA in lung transplant recipients was significantly lower after institution of routine Aspergillus prophylaxis (4.9% vs. 18.2%, P < 0.05). CONCLUSIONS: The highest incidence and attack rate of invasive aspergillosis among solid organ transplant recipients occurs in lung transplant recipients and supports the routine use of Aspergillus prophylaxis for at least one year after transplantation in this group.

Adult↗
PubMed1995

Use of risk projection models for the comparison of mortality from radiation-induced breast cancer in various populations.

The aim of our study is to compare lifetime risk estimates for radiation-induced breast cancer between various populations. Some epidemiological studies, mainly on Japanese A-bomb survivors, but also on North American populations irradiated for medical reasons, provide risk coefficients for excess mortality from breast cancer after exposure to ionizing radiation. For this comparative study, these risk coefficients have been transferred into the Japanese, American, and French populations, using demographic data, risk projection models, and assuming an individual acute exposure. The lifetime risk estimates are similar in the three populations when the additive projection model is used because of the similarity of the life tables of the three countries. However, using the multiplicative model, large differences appear due to the discrepancies in the baseline breast cancer rates between the Japanese and Occidental populations. It is for this reason that transfer of risk coefficients fitted on the Japanese population data must be considered with caution when applied to an Occidental population. Lifetime risk estimates for a given population, the French population for example, are largely dependent on the risk coefficients considered from various epidemiological studies. Nevertheless, for each source of data, they are higher with the multiplicative model than with the additive one. Moreover, it should be noted that data from medical irradiation lead to higher risk estimates when using the additive model, whereas studies of the A-bomb survivors lead to higher risk estimates with the multiplicative model. This comparative study points out the variations of the lifetime risk calculations according to the baseline breast cancer mortality rates of the three populations and with the use of different mathematical projection models.

Adult↗
PubMed1993

[Radiation-induced tumors of the nervous system in man].

The risk of developing a tumor of the nervous system in humans is analysed in several studies of populations, exposed to ionising radiation for medical reasons, or exposed to military or occupational radiation. The main data come from series of patients who underwent radiotherapy during childhood: a high incidence of tumors of the nervous system is found after irradiation of one to a few grays as treatment of a benign disease (especially tinea capitis), as well as after irradiation at higher doses of a few tens of grays for the treatment of cancer (in particular cerebral irradiation in acute lymphoblastic leukaemia). The type of radiation-induced tumors is variable, but meningioma is more frequent after low doses and glioma and sarcoma after higher doses used in the treatment of neoplastic diseases. A dose-effect relationship appeared between the risk of tumor of the nervous system and the radiation dose. The risk was higher when radiation was delivered at a younger age. Much less data are available after radiotherapy in the adulthood, but an increased risk of cerebral tumor appears in the series of ankylosing spondylitis patients. As for the exposures to radiodiagnosis exams, the main problem is the risk of cerebral tumor in children whose mother has undergone abdominal or pelvic X-rays during pregnancy. No risk of neurologic tumor was found in the A-bomb survivors irradiated at Hiroshima and Nagasaki. Occupational exposure to ionising radiation has been incriminated in the first radiologists exposed to high doses. In nuclear industry workers, the results of epidemiological studies are contradictory and at the present time it is not possible to link their radiologic exposure with a risk of tumor of the nervous system. In populations living near nuclear plants, mortality due to tumors of the nervous system was not increased.

Adolescent↗
PubMed1992

[Increase of cancers of the thyroid gland in children in Byelarus].

Last September, "Nature" reported a great increase in the frequency of thyroid cancer in children in Belarus. Some additional data are now available and strengthen the previous findings. The overall incidence of thyroid cancer in children rose from an average of four cases per year till 1989 to more than 50 in 1991 and 1992. Nearly all of the 146 cancers recorded since 1986 are papillary carcinomas. Moreover these cancers appear relatively aggressive. The occurrence of such an increase within a few years of exposure--and only in children--is quite unexpected. Therefore, it seems very important to monitor trends in future and more information is needed, as different questions remain unanswered: dosimetry, diagnosis methods, other thyroid diseases... In conclusion, the authors stress on the very importance of iodine prophylaxis in case of an accidental contamination by radioisotopes of iodine. It seems possible that cancer excess would have been less important, if Belarus children had been given stable iodine.

Accidents↗
PubMed1987

[Non-Hodgkin's malignant lymphoma with primary localization in the breast. Apropos of 2 cases: review of the literature].

The malignant non-hodgkinian lymphoma (M.N.H.L.) with pripary mammary localization is relatively rare, but deserves to be accounted for in the evaluation of breast cancers. The diagnosis of the primary localization in the breast responds to definite criteria, well established by Wiseman and Liao. On the other hand, the initial mammary localization is more frequent, revealing a hemato-sarcoma clinically silent until then, but with nodal spread (most of the time lumbo-aortic). The problem is to know whether it is possible, in front of a breast nodule, to evoke lymphoma in view of some clinical and paraclinical characteristics. An accurate pathological diagnosis (International Formula for clinical use of the National Cancer Institute-1982) and a minutious work-up for spread determination (AnnArbor Classification) represent the two essential aspects of the prognosis. It is advised to resort to surgical excision-biopsy in order to obtain an exact histology with analysis of immunological markers, rather than an extemporaneous examination which often leads to the wrong diagnosis of cancer and a mutilating and unnecessary surgery. Progresses in chemotherapy have greatly contributed to improve survival of these hematosarcomas with extranodal localization, which remain however a neoplastic disease with a disseminating tendency.

Aged↗
PubMed1983

[Will Naegleria fowleri become a public health problem?].

Primary amebic meningoencephalitis due Naegleria Fowleri is a rare disease. Less than 100 cases have been published and non have been described in France. Historical, clinical, taxonomical and epidemiological aspects of this infection are reviewed. The recent publication of a case which resolved under treatment and the discovery of Naegleria Fowleri in French warm waters incite to carry on pathogenetic and immunological research and field investigations for this parasite in order to understand its ecology.

Adolescent↗
PubMed1983

[Effect of atmospheric pollution (SO2--dust) and meteorological conditions on mortality in Paris between 1969 and 1976].

The short-term effect of environmental factors (atmospheric pollutants, meteorology) on mortality are studied with 8 years of continuous daily data collected in Paris (1969-1976). Mortality data are specified using daily-rate of death, according to diagnosis and age-range. Chosen pollutants are acidity and smoke. Meteorological conditions are identified by synoptic data and local parameters (pressure, temperature, humidity). Relations between mortality and pollution, and their interaction with meteorological conditions, have been described with several statistical methods. Among results, it is shown for example that relation of pollution levels with total daily deaths is not very clear but it becomes very significant for very old population; the strongest relation occurs for deaths connected with respiratory diseases, with a maximum 2 or 3 days after, but possibly later. Climatic factors such as synoptic situation and temperature have also influence on mortality but not so significant as pollution.

Aged↗
PubMed1983

[Descriptive analysis of episodes of atmospheric pollution occurring in Paris between 1969 and 1976 and their consequences on daily mortality].

Simultaneous evolution of daily data collected in Paris (1969-1976) concerning mortality on the one hand, and pollution and meteorology on the other hand, is described during two specific episodes: the first, observed in december 1969, is a high mortality one, due to an influenza epidemic; the other, observed in december 72-january 73, is related to high pollution levels. Mortality data are specified using daily-rate of death, according to diagnosis and age-range. Chosen pollutants are acidity and smoke. Meteorological conditions are identified by synoptic data and local parameters (pressure, temperature and humidity). Among results, it is shown for example that the mortality-excess is mainly due to respiratory diseases, that it concerns elderly persons when heavy pollution, but younger persons (less than 75 years old) when influenza epidemic; pollution effects are not detected when daily acidity level is less than 300 micrograms/m3 but they systematically appear for level more than 400 micrograms/m3. "Compensation" effects (mortality-rate decrease occurring after high mortality days) have been pointed out. Tentative interpretation is proposed, including also temperature and humidity effects, and validation is necessary to do.

Adult↗
PubMed1976

Interactions of short chain aliphatic hydrocarbons with human blood and haemoglobin A solutions.

The solubilities of methane, propane, butane and propylene were measured in human whole blood, human plasma and defatted haemoglobin solutions at 37 degrees C. For these four hydrocarbons the solubility coefficient (alpha = ml of gas STPD dissolved in one mal of the solvent under a pressure of one atmosphere) is higher in plasma than in an isoosmolar aqueous solution and higher in whole blood than in plasma. This is due to the presence of proteins and particularly of haemoglobin as shown by the dependence of alpha upon the concentration of haemoglobin in the medium. O2 capacity of human blood is not altered in the presence of these hydrocarbons and its affinity for O2 is slightly decreased.

Air Pollutants↗