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Biomedical subjects

M Charrel

Publications and source records attributed to M Charrel.

At least 19 recordsLinked to original sources
PubMed2000

A low budget luminometer for sensitive chemiluminescent immunoassays.

We have designed a simple luminometer based on a reasonably priced Peltier-cooled charge-coupled device (CCD) camera, housed in a light-tight box, with straightforward lens imaging and a simple platform for a microtitre or other assay format. The quantitative readout of the CCD image is recorded on a PC using customised software. The instrument can be assembled in a standard university workshop for under pound3000, compared with the cheapest commercial instruments retailing at pound10,000 and above. Consistent with the general view on chemiluminescent assays, the sensitivity is 10-100 times greater than that obtained with parallel ELISA's using a chromogenic substrate. A unique feature of the CCD format is that it enables assays to be carried out on arrays of minidots and even nanodots of antigen on the floor of each microtitre well. This permits direct comparison and standardisation of reactivity of a single sample against several antigens and economy in the use of reagents, test sample and technician time; finger-prick samples of blood can be analysed. The instrument should have widespread applicability in developing countries and, indeed, in any laboratories with hard-pressed budgets.

Animals↗
PubMed1999

3D imaging of the 58 kDa cell binding subunit of the Helicobacter pylori cytotoxin.

Pathogenic strains of Helicobacter pylori produce a potent exotoxin, VacA, which intoxicates gastric epithelial cells and leads to peptic ulcer. The toxin is released from the bacteria as a high molecular mass homo-oligomer of a 95 kDa polypeptide which undergoes specific proteolytic cleavage to 37 kDa and 58 kDa subunits. We have engineered a strain of H. pylori to delete the gene sequence coding for the 37 kDa subunit. The remaining 58 kDa subunit is expressed efficiently and exported as a soluble dimer that is non-toxic but binds target cells in a manner similar to the holotoxin. A 3D reconstruction of the molecule from electron micrographs of quick-freeze, deep-etched preparations reveals the contribution of each building block to the structure and permits the reconstruction of the oligomeric holotoxin starting from individual subunits. In this model P58 subunits are assembled in a ring structure with P37 subunits laying on the top. The data indicate that the 58 kDa subunit is capable of folding autonomously into a discrete structure recognizable within the holotoxin and containing the cell binding domain.

Bacterial Proteins↗
PubMed1998

Characterisation of a monoclonal antibody and its use to purify the cytotoxin of Helicobacter pylori.

The vacuolating cytotoxin (VacA) is a major virulence factor of Helicobacter pylori which is not yet well characterised and is difficult to obtain in large quantities. Here we describe the production of a monoclonal antibody that recognises the native but not the denatured form of VacA. The antibody can be efficiently used in affinity chromatography for one-step purification of large quantities of VacA from culture supernatants. Elution at acidic pH dissociates the oligomeric molecule into monomers that reanneal in a time-dependent fashion. The purified cytotoxin is able to bind, and to intoxicate HeLa cells.

Animals↗
PubMed1995

Influence of photoisomers in bilirubin determinations on Kodak Ektachem and Hitachi analysers in neonatal specimens study of the contribution of structural and configurational isomers.

We compared data obtained with the Kodak Ektachem and Hitachi 717 Analysers and HPLC from 83 neonates under phototherapy. Total bilirubin values determined with the Kodak and Hitachi are in good agreement, but we observed a large discrepancy in the results for conjugated (Kodak) and direct (Hitachi) bilirubin. HPLC revealed that all the samples contained configurational isomers, while only 7.7% and 30.8% contained conjugated bilirubin and structural isomers, respectively. We developed a device for the specific and quantitative production of configurational or structural isomers, by irradiation with blue or green light. In vitro, total bilirubin values are coherent for the routine analysers in the presence of configurational or structural isomers. With configurational isomers, unconjugated bilirubin (Kodak) is lower than total bilirubin (Kodak), and conjugated bilirubin (Kodak) is always equal to zero, so the apparatus gives a false positive response for delta bilirubin. In contrast, the direct bilirubin (Hitachi) is constant. Furthermore, in the presence of structural isomers, unconjugated bilirubin (Kodak) is unexpectedly higher than total bilirubin (Kodak), conjugated bilirubin (Kodak) is proportional to the quantity of these isomers, and direct bilirubin (Hitachi) is constant. The contribution of photoisomers in bilirubin measurements is discussed.

Bilirubin↗
PubMed1993

Abnormal bilirubin binding to human serum albumin in a patient with unusual myeloma immunoglobulin G.

The binding of bilirubin was analysed in the serum of a patient with unusual myeloma. This patient presented an acquired Von Willebrand's disease due to the presence of a ternary complex formed by one molecule of myeloma immunoglobulin G and two molecules of albumin (Harlé et al. La Presse Médicale 19, 1661-1664 (1990)). The binding characteristics of bilirubin--number of sites (n) and association constants (k)--were estimated in the serum of the proband, and compared with those of purified human serum albumin and pooled normal human serum. The data suggest that complex formation between albumin and immunoglobulin induces abnormal bilirubin binding in the patient's serum, which becomes apparent when the bilirubin/albumin ratio exceeds 1.3. This abnormal binding may be due to conformational changes of the albumin molecule in the complex. The greatly increased number of lower affinity binding sites for bilirubin is certainly due to the abnormally high concentration of myeloma immunoglobulin G in the serum of the patient.

Bilirubin↗
PubMed1992

[Neonatal hyperchloremia related to bromide poisoning].

Hyperchloremia may reveal bromism during the neonatal period. The authors report on two cases of neonatal bromism. The first case concerns triplets without clinical signs although the children and their mother displayed hyperchloremia. In the other case a 6 week old infant displayed neurological abnormalities associated with hyperchloremia and elevated plasma bromide levels.

Adult↗
PubMed1992

[Comparative study of LpAI lipoparticles, HDL cholesterol and apolipoprotein AI in a control population, in a group of subjects with coronary diseases, and in a group of subjects with angiographically normal coronary vessels].

A new method for directly measuring LpAI lipoparticles containing apolipoprotein AI, but not apolipoprotein AII, is now disponible for laboratories. Concentrations of LpAI were measured in serum from 158 presumably healthy normolipidemic subjects (72 male, 86 female), for the age group 30-60 years. Concentrations of LpAI were also measured in subjects with angiographically defined coronary artery disease (coro+) and without angiographically defined coronary artery disease (coro-). After comparison of the groups, lipoprotein particle LpAI did not appear to be a better discriminative marker than HDL cholesterol or apolipoprotein AI for atherogen risk.

Adult↗
PubMed1989

Breast cancer and alcohol consumption: a case-control study in northern Italy.

From 1983 to 1986, a population-based case-control study of alcohol and breast cancer (250 cases and 499 controls) was conducted in a grape-farming area of northern Italy, where wine consumption is widespread. In the study population, 30% of women were abstainers and 15% reported alcohol intakes of 30 g/day or more. After adjustment for potential confounders, no appreciable association was evident for alcohol consumptions as high as 40 g/day. Women reporting intakes of more than 40 g/day showed approximately a 2-fold increase in the risk of breast cancer (relative risk, 1.9; 95% confidence interval, 1.1-3.3). A 2-fold increase in risk was observed for consumptions of more than 40 g/day of alcohol from wine, the most common alcoholic beverage in this population. These findings suggest that an association between alcohol intake and breast cancer may exist. However, the moderate risk observed seems to be limited to the relatively small group of women consuming daily amounts of alcohol in excess of 40 g, the equivalent of about half a bottle of wine or more.

Alcohol Drinking↗
PubMed1989

Calorie-providing nutrients and risk of breast cancer.

A case-control study was conducted in Italy to investigate the role of diet in breast cancer. Cases were 250 women with breast cancer, and controls were a stratified random sample of 499 women from the general population. A dietary history questionnaire was used to measure the intake of total fat, saturated fat, animal proteins, and other macronutrients. In multivariate analyses, the relative risks of breast cancer for women in the highest quintile of consumption of saturated fat and animal proteins were 3.0 (95% confidence interval, 1.9-4.7) and 2.9 (1.8-4.6), respectively. A reduced risk was found for women who derived less than 28% of calories from fat versus greater than 36%. A similarly reduced risk was found for women who derived less than 9.6% of calories from saturated fat or less than 5.9% from animal proteins. These data suggest that during adult life, a reduction in dietary intake of fat and proteins of animal origin may contribute to a substantial reduction in the incidence of breast cancer in population subgroups with high intake of animal products.

Adenocarcinoma↗
PubMed1988

Comparison of bacterial indicators and sampling programs for drinking water systems.

A total of 48 French villages were selected for a survey of water quality from February 1983 to June 1984 as part of an epidemiological study conducted in the rural area of the Rhône-Alpes region. Water samples were collected and analyzed on a weekly basis in each village. Bacteriological analysis of each water sample included enumeration of standard plate count bacteria, total and thermotolerant coliforms, and fecal streptococci. The water quality regulations are examined as to the analysis frequency, the volume of samples, and the relationship between the various bacterial indicators. Analyzing 300-ml, instead of 100-ml, samples tends to generate better information on single water samples. However, if many samples are analyzed over time from the same community, the value of using large volumes of water samples is diminished. The comparisons between bacterial indicators showed that the information obtained from the various indicators was very similar. However, fecal streptococci had a better predictive value of a negative test than coliforms with respect to the French standards.

Bacteria↗
PubMed1988

A controlled evaluation of a health education programme for pregnant women in rural areas.

A controlled evaluation of health education for pregnant women was implemented from 1983 to 1985 in the French north alpine rural area with a quasi-experimental design. Altogether 116 villages (88,983 inhabitants) constituted the pilot zone where the programme took place. This was matched with a control zone of 114 villages (78,800 inhabitants) where routine antenatal surveillance was not changed. The programme involved a large group of health and social workers and institutions and several educational devices. There was a total of 3143 births to the study women during the programme. In all the 45 maternity clinics of the region the mothers were questioned as to their pregnancy history and delivery outcome. The programme succeeded in increasing, in the pilot zone, the proportion of women who benefited from a monthly antenatal visit, whereas no positive trend was shown in the control zones, even when controlling for some identified potential confounders (age and distance to health care providers). Similarly, women in the pilot zone were more likely to attend delivery preparation sessions than women in the control zone. However, many conditions revealed no differential modification in the two study zones. Perinatal morbidity is lower in the north alpine rural area than in the whole country. These results favour further development of social policies for pregnancy and of prenatal care, complemented by better information and training for health and social workers; they also favour better information as to medical monitoring, hygiene, and social rights related to pregnancy.

Female↗
PubMed1988

[A network of epidemiological information in community medicine practice: methodological principles of the VENUS Program].

Implementation of epidemiological studies involving the participation of large networks of ambulatory care physicians requires prior resolution of the methodological dilemma between a "volunteer sentinel doctors" approach and one based on sampling techniques. A study of the VENUS program (concerning Sexually Transmitted Diseases) illustrates this latter approach for which formulae are proposed for estimating the rate of incidence in the population. Methodological implications of this technique are commented upon, and the complementary indications for the two techniques for gathering information on ambulatory morbidity are discussed.

Ambulatory Care↗
PubMed1988

[Birth in the rural area: an evaluation of prevention of perinatal risk in rural areas].

A study was designed and implemented between 1983 and 1985 in order to evaluate the effectiveness of a personalized health education program designed for pregnant women in the specific context of rural areas. The action succeeded in increasing the proportion of women benefiting from a monthly antenatal surveillance but many other results underline the limitations of such prevention programs that would be restricted to the information of the general public and health professionals. Perinatal morbidity in the north-alpine rural area ranks very favourably compared to the regional or national figures.

Evaluation Studies as Topic↗
PubMed1987

A follow-up study of gastro-intestinal diseases related to bacteriologically substandard drinking water.

In a prospective follow-up study conducted in 52 French alpine villages, one weekly water sample was taken in each village provided with untreated ground water and analyzed as to the presence of four indicator bacteria: total plate count, total coliforms, thermotolerant (fecal) coliforms, and fecal streptococci. Cases of acute gastro-intestinal disease (AGID) occurring among 29,272 inhabitants were reported through physicians, pharmacists, and primary school teachers. A loglinear model identified fecal streptococcus (FS) as the best predictor; the presence of fecal coliforms enhanced the effect of FS. The total bacteria count and the total coliforms had no independent contributions. A threshold analysis suggested that any level of indicator bacteria above zero was associated with an excess of AGID.

Child↗
PubMed1986

[Inflammatory syndrome and changes in plasma proteins].

Inflammation can be considered as a reactional process towards an injury of any etiology. It is clinically characterized by the four major points described by Celse. The symptoms are usually associated with fever and with a biological syndrome including an increased sedimentation rate related to an elevation of inflammatory plasma proteins. The Acute Phase Reactant Proteins (orosomucoid, alpha 1-antitrypsin, alpha 1-antichymotrypsin, haptoglobin, ceruloplasmin, C reactive protein and fibrinogen) are released by the hepatocytes. The complement components C3 and C4, transferrin and alpha 2-macroglobulin can also be generated by the macrophages. At inflammation sites, the activated host phagocytes release a Leukocytic Endogenous Mediator (LEM) or Interleukin I. A circulating cleavage product of Interleukin I, called "Proteolysis Inducing Factor" induces an increased muscle proteolysis and hepatic amino acids uptake for inflammatory proteins synthesis, principaly in the form of Acute Phase Reactant Proteins. Furthermore, this monokin stimulates the T4 helpers lympocytes production of a lymphokin: Interleukin II. There is no "inflammation protein" characterized by the 5 criteria of the Clinical Biology French Society. Therefore the association of a high turn over protein (CRP) and a low turn over one (orosomucoid and/or haptoglobin) is usefull for the detection of an inflammatory process and to evaluate a therapeutic efficiency. These proteins are usually selected for early diagnosis of neonatal bacterial infections and for the diagnosis of myocardial infarction. In the present time, numerous studies using statistical methods try to separate inflammatory processes according to their etiology.

Acute-Phase Proteins↗
PubMed1986

[Longitudinal study of the risks related to the consumption of water not conforming to bacteriological norms].

A prospective follow-up study lasting 18 months in 1983-1984 was conducted in 50 villages in order to assess the risk related to the consumption of drinking water which did not meet the bacteriology standards. 119 physicians, 52 pharmacists and 118 primary-school teachers enumerated the cases of acute gastro-intestinal diseases observed among a population of 29,272 inhabitants. A weekly water sample was analysed in each village as to the presence of four indicator germs of fecal contamination: total plate count, total coliforms, fecal coliforms (thermotolerant) and fecal streptococci. 1,950 cases of acute gastro-intestinal diseases were registered by the physicians and pharmacists during a population experience of 1,873,303 persons-weeks, i.e. an incidence density of 1.06 X 10(-3) cases per person-week. The risk notified by the school teachers among children aged 7 to 11 was higher: 16.3 X 10(-3) cases per child-week. The villages were classified in 3 groups, according to the proportion of substandard samples: "good", "intermediate", and "bad" categories. The relative risk contrasting the "bad" and "good" villages was 3.5 for the cases notified by the physicians and the pharmacists among the general population (95% confidence interval = 2.5-4.8); it was 1.7 for the cases reported by the teachers among the children (95% confidence interval = 1.5-1.9). This concordant difference was very significant but not constant across the 18 months of the survey. The authors conclude that the bacteriology standards are a relevant indicator of a health hazard.

France↗