Biomedical subjects

S Robin

Publications and source records attributed to S Robin.

At least 19 recordsLinked to original sources

PubMed2006

[Identification of disturbed pupils within the educational system: comparative evaluation of two systems of professional practices with different approaches to providing guidance].

A study was carried out in the Poitou-Charentes region to assess and compare the professional practices in secondary schools offering two different systems of response and guidance. The evaluation method was based upon an analysis of the rates of concurrence between the evaluation of the students' answers to an epidemiological self-administered questionnaire filled out before a clinical interview, and the conclusions of the psychiatric nurses after this interview. Comparisons between the specific system and the standard general system of National Education highlighted an increased capacity of professionals in the more specific system to distinguish a high risk of suicidal tendencies from a low risk or absence of risk, while the standard system was more effective in screening and detecting overall levels of well-being across the entire student population. Moreover, the guidance support and counseling proposed in the specialised system seemed to better meet the pupils' needs more accurately than in the standard system.

Adolescent↗

PubMed2005

[Walking tests: a step forward for functional cardiorespiratory assessment].

Exercise testing provides information on physical capacity during exercise in addition to spirometric measures of lung function or assessment on treadmills or ergonomic cycle. The "gold standard" assessment of exercise tolerance is measured in the laboratory using treadmills or ergonomic cycle but the necessary equipment is expensive and may not be readily accessible; such tests require people used to work with children. Walking tests are field tests providing a valid and easily accessible method of measuring function-limited exercise tolerance in patients with respiratory or cardiac chronic diseases. These walking tests are non-threatening, inexpensive, easy to perform and to understand for children. Walking tests performed in daily practice are the following: "time-based" tests (2-, 6- or 12-min walking test), 3-min step test (on a step) and the shuttle walking test. It may be a useful measure to assess therapeutic intervention and provide information on the prognosis. They are simple and safe methods to evaluate quality of life in these patients.

Adolescent↗

PubMed2005

Plasma homocysteine is related to folate intake but not training status.

BACKGROUND AND AIM: Lifestyle including intakes of several essential nutrients and physical activity are of particular interest in reducing plasma total homocysteine concentration (tHcy), a risk factor for cardiovascular diseases. The aim of this study was to determine in athletes, whether dietary factors such as intakes of folate, vitamin B6 and B12 were associated with lower plasma tHcy, and whether this depended on daily energy expenditure (EE) and type of physical activity performed (aerobic, anaerobic, intermittent). METHODS: Seventy-four well-trained athletes completed 7-day food and activity records in a cross-sectional study. Blood was sampled on day 8. RESULTS: Percentage of vegetal protein, vitamin B6, and folate intakes were higher and tHcy was lower (1) in athletes with high EE (> 16.72 MJ/d) compared to athletes with lower EE; (2) in aerobic athletes compared to intermittent athletes and sedentary subjects. After backward step by step analysis, folate intake was the only significant variable retained in the model to explain tHcy variability. Moreover, after introducing folate intake as a covariate in ANOVA tests, group effects on tHcy were no longer significant. Nutrient density of folate was inversely correlated to tHcy in athletes (r = -0.33; P = 0.004). CONCLUSION: High energy intake (> 16.72 MJ/d) allows the necessary folate intake (> 500 microg/d) for tHcy decrease to occur, which is moreover favored by aerobic activity. The mechanism underlying low tHcy in relation to high EE could only play a minor role when compared to the effect of dietary folate intake on tHcy.

Adult↗

PubMed2005

Factors associated with time to neonatal diarrhoea in French beef calves.

A prospective study was carried out on 92 randomly selected beef herds in the Midi-Pyrenees region in France. The objective was to determine factors associated with time to neonatal gastroenteritis. By taking into account the "intra-herd" correlation in failure time (in the semiparametric Cox model), we identified 12 management risk factors associated with hazard of diarrhoea. Some previously have been identified, but "new" risk factors were feeding of corn silage and the incidence of diarrhoea in the last season. We used the two main approaches which are often reviewed: marginal and frailty Cox models. Our results show that these two models give different parameter estimates, so the choice of the model remains crucial.

Animal Husbandry↗

PubMed2005

[Exercise performance of patients with alveolar proteinosis].

INTRODUCTION: Cardiopulmonary exercise testing (CPET) is used to evaluate the severity of interstitial lung diseases, particularly when lung function is normal. The aim of this study was to analyse exercise capacity of patients with alveolar proteinosis. METHODS: We studied 7 patients undergoing alveolar proteinosis (aged 38 +/- 5 years), Three patients complained of exertional dyspnoea, 2 had a reduced vital capacity and 5 had a DLCO of less than 75% predicted. CPET was performed on a bicycle ergometer using a standard incremental protocol. RESULTS: CPET was symptom limited for all patients.. At peak exercise, VO2 was severely reduced (19.5 +/- 5.2 ml/kg/min, 58 +/- 9%). All patients developed hyperventilation. Ventilatory reserve was 42 +/- 11% of MMV, and dead space ratio (Vd/Vt) reached 0.29 +/- 0.05. Cardio-circulatory adaptation was normal (maximum heart rate 83 +/- 9%; VO2/heart rate 70 +/- 10%). Six patients exhibited gas exchange abnormalities at peak exercise (including 4 patients having a normal vital capacity): P(A-a)O2 56 +/- 18mm Hg; PaO2 65 +/- 18 mm Hg. CONCLUSION: Patients undergoing alveolar proteinosis have severe impairment of aerobic capacity and gas exchange on exercise. CPET appears to be useful for therapeutic management.

Adaptation, Physiological↗

PubMed2004

Determination of the differentially expressed genes in microarray experiments using local FDR.

BACKGROUND: Thousands of genes in a genomewide data set are tested against some null hypothesis, for detecting differentially expressed genes in microarray experiments. The expected proportion of false positive genes in a set of genes, called the False Discovery Rate (FDR), has been proposed to measure the statistical significance of this set. Various procedures exist for controlling the FDR. However the threshold (generally 5%) is arbitrary and a specific measure associated with each gene would be worthwhile. RESULTS: Using process intensity estimation methods, we define and give estimates of the local FDR, which may be considered as the probability for a gene to be a false positive. After a global assessment rule controlling the false positive error, the local FDR is a valuable guideline for deciding wether a gene is differentially expressed. The interest of the method is illustrated on three well known data sets. A R routine for computing local FDR estimates from p-values is available at http://www.inapg.fr/ens_rech/mathinfo/recherche/mathematique/outil.html. CONCLUSIONS: The local FDR associated with each gene measures the probability that it is a false positive. It gives the opportunity to compute the FDR of any given group of clones (of the same gene) or genes pertaining to the same regulation network or the same chromosomic region.

Acute Disease↗

PubMed2004

[Continuous infusion of remifentanil and target-controlled infusion of propofol for coronary surgery in elderly patients: comparison with continuous infusion of remifentanil and propofol].

OBJECTIVES: Comparison of the length of mechanical ventilation and postoperative complications after coronary surgery in elderly patients anaesthetised with propofol associated with either alfentanil or remifentanil. STUDY DESIGN: Retrospective study with an historic control group. PATIENTS: Three hundred thirty-eight consecutive patients (75-year-old or more) undergoing isolated coronary surgery. One hundred and fifty seven patients operated between January 1998 and June 2000 received alfentanil (1 microg/kg/minute) with a manually control infusion of propofol, 181 operated between July 2000 and 2002, remifentanil 0.25 microg/kg/minute with target controlled infusion of propofol (target blood concentration: 1.5 to 2 microg/ml). METHODS: The two groups were compared for preoperative and surgical data. The length of mechanical ventilation, stay in ICU and the main postoperative complications were compared between the two groups. RESULTS: Length of mechanical ventilation was significantly reduced in the remifentanil group (6 +/- 9 h vs. 13 +/- 63 h ; p <0.0001), 70% of the patients were extubated before the 6th postoperative hours against 53% in the alfentanil group (p =0.0023). This was not associated with a reduction of stay in ICU or postoperative complications. During surgery, an increased used of vasopressor was observed in the remifentanil group (40.2% vs 2.4% ; p <0.0001) with a postoperative elevation of blood concentration of CKMb (35.7 +/- 38.2 microg/l, vs. 27.7 +/- 31.9 microg/l, p =0.02). CONCLUSION: Elderly patients undergoing coronary surgery were extubated earlier with remifentanil. However, this had no effect on duration of ICU stay but was associated with an increased used of vasopressor.

Aged↗

PubMed2003

Mapping osmotic adjustment in an advanced back-cross inbred population of rice.

Osmotic adjustment is one of several characters putatively associated with drought tolerance in rice. Indica cultivars are known to have a greater capacity for osmotic adjustment than japonica cultivars. We developed an advanced back-cross population using an indica donor, IR62266-42-6-2, to introgress osmotic adjustment into an elite japonica cultivar, IR60080-46A. One hundred and fifty BC(3)F(3) families were genotyped using microsatellites and RFLP markers, and a few candidate genes. We evaluated osmotic adjustment in these lines under greenhouse conditions using the re-hydration technique. Using the composite interval mapping technique, we detected 14 QTLs located on chromosomes 1, 2, 3, 4, 5, 7, 8 and 10 that together explained 58% of the phenotypic variability. Most, but not all, of the alleles with positive effects came from the donor parent. On chromosome 8, two QTLs were associated in repulsion. The QTL locations were in good agreement with previous studies on this trait on rice and in other cereals. Some BC(3)F(3) lines carried the favorable alleles at the two markers flanking up to four QTLs. Intercrossing these lines followed by marker-aided selection in their progenies will be necessary to recover lines with levels of osmotic adjustment equal to the donor parent. The advanced back-cross strategy appeared to be an appropriate method to accelerate the process of introgressing interesting traits into elite material.

Adaptation, Psychological↗

PubMed2003

Maximal lactate steady state does not correspond to a complete physiological steady state.

The purpose of this study was to verify whether the maximal lactate steady state (MLSS) corresponds to a physiological steady state. Eight male trained subjects performed a 30-min test on a cycle ergometer at a constant power corresponding to their own MLSS which had been previously determined. No significant variation was observed between the 10th and the 30th min for arterial lactate concentration, redox state, arterial oxygen pressure, arterial oxygen saturation, bicarbonates concentration, base excess, hematocrit, hemoglobin concentration, plasma volume, oxygen uptake, carbon dioxide output, gas exchange ratio, minute ventilation, ventilatory equivalents for oxygen and carbon dioxide, and arterial systolic blood pressure values. However, arterial carbon dioxide pressure and pH values were significantly different between the 10th and the 30th min (p < 0.01). Respiratory rate values and heart rate significantly increased (p < 0.01). These results indicate that MLSS does not correspond to a complete physiological steady state.

Adaptation, Physiological↗

PubMed2002

Trans-complementation of an endonuclease-defective tagged I element as a tool for the study of retrotransposition in Drosophila melanogaster.

I factors are non-LTR retrotransposons of Drosophila melanogaster that transpose at high frequency in the germline of females resulting from appropriate crosses, allowing in vivo studies of the retrotransposition process. Reverse transcription of a full-length RNA intermediate is thought to occur at the site of integration, using a 3' hydroxyl group generated by endonucleolytic cleavage of the genomic DNA to prime synthesis of the first cDNA strand. This target-primed reverse transcription (TPRT) process is mediated by endonuclease and reverse transcriptase activities encoded by the element. We have designed a molecularly tagged, endonuclease-defective I element that can be mobilised with high efficiency by constructs that express the product of the I factor ORF2 in trans. This indicates that the endonuclease activity required for retrotransposition of the I factor can be provided in trans. Using this system, we show that the endonuclease domain of the R1Bm retrotransposon from Bombyx mori cannot functionally replace that of the I factor.

Animals↗

PubMed2002

Occurrence probability of structured motifs in random sequences.

The problem of extracting from a set of nucleic acid sequences motifs which may have biological function is more and more important. In this paper, we are interested in particular motifs that may be implicated in the transcription process. These motifs, called structured motifs, are composed of two ordered parts separated by a variable distance and allowing for substitutions. In order to assess their statistical significance, we propose approximations of the probability of occurrences of such a structured motif in a given sequence. An application of our method to evaluate candidate promoters in E. coli and B. subtilis is presented. Simulations show the goodness of the approximations.

Algorithms↗

PubMed2001

Extracting biological information from DNA arrays: an unexpected link between arginine and methionine metabolism in Bacillus subtilis.

BACKGROUND: In global gene expression profiling experiments, variation in the expression of genes of interest can often be hidden by general noise. To determine how biologically significant variation can be distinguished under such conditions we have analyzed the differences in gene expression when Bacillus subtilis is grown either on methionine or on methylthioribose as sulfur source. RESULTS: An unexpected link between arginine metabolism and sulfur metabolism was discovered, enabling us to identify a high-affinity arginine transport system encoded by the yqiXYZ genes. In addition, we tentatively identified a methionine/methionine sulfoxide transport system which is encoded by the operon ytmIJKLMhisP and is presumably used in the degradation of methionine sulfoxide to methane sulfonate for sulfur recycling. Experimental parameters resulting in systematic biases in gene expression were also uncovered. In particular, we found that the late competence operons comE, comF and comG were associated with subtle variations in growth conditions. CONCLUSIONS: Using variance analysis it is possible to distinguish between systematic biases and relevant gene-expression variation in transcriptome experiments. Co-variation of metabolic gene expression pathways was thus uncovered linking nitrogen and sulfur metabolism in B. subtilis.

Arginine↗

PubMed2001

[Pulmonary hypertension screening in systemic scleroderma: a cohort study of 67 patients].

PURPOSE: Pulmonary hypertension is a severe complication of systemic sclerosis and has emerged as a major cause of morbidity and mortality in this condition. Treatment is all the more efficient as pulmonary hypertension is early diagnosed. A good knowledge of the clinical, biological and functional features of pulmonary hypertension in systemic sclerosis is therefore necessary to suspect and to diagnose pulmonary hypertension as early as possible. METHODS: Sixty seven patients with systemic sclerosis were retrospectively studied. We compared clinical, immunological, functional (spirometry) and morphological (pulmonary fibrosis) features according to the presence (n = 25) and the characteristic of pulmonary hypertension (isolated or secondary) or the absence (n = 42) of pulmonary hypertension, assessed by Doppler echocardiography. RESULTS: CREST syndrome (calcinosis, Raynaud's phenomenon, oesophageal involvement, sclerodactyly and telangiectasia) was more frequent in patients with isolated pulmonary hypertension than in patients without PH (72.7% vs 28.5%, P < 0.05; odds-ratio [OR] = 6.6) and dyspnea was more severe (P < 0.001; OR = 11.4). The age at time of pulmonary hypertension diagnosis was higher in patients with secondary pulmonary hypertension than in patients with isolated from (median: 62.5 years (range: 32-35) vs 53 years (range: 37-85), P < 0.05). Patients with isolated pulmonary hypertension had anticardiolipin antibodies more frequently than patients without pulmonary hypertension (72.7% vs 35.7%, P < 0.05). Isolated reduction of diffusing capacity was preferentially observed among patients with isolated pulmonary hypertension than among those without pulmonary hypertension. A linear relation between systolic pulmonary artery pressure values and diffusing capacity values (r = 0.72, P < 0.01) was found. Isolated reduction of diffusing capacity was more frequent in patients with isolated pulmonary hypertension than in patients without pulmonary hypertension (63.6% vs 14.3%, P < 0.001; OR = 10.5). CONCLUSION: The severity of pulmonary hypertension in systemic sclerosis justifies a systematic screening by Doppler echocardiography and diffusing capacity measurement. Our results allow us to better define the characteristics of sclerodermic patients with isolated or secondary pulmonary hypertension. The search for pulmonary hypertension should be repeated with time and clinicians should be particularly vigilant in the case of a patient presenting these characteristics.

Adult↗

PubMed2001

Numerical comparison of several approximations of the word count distribution in random sequences.

The exact distribution of word counts in random sequences and several approximations have been proposed in the past few years. The exact distribution has no theoretical limit but may require prohibitive computation time. On the other hand, approximate distributions can be rapidly calculated but, in practice, are only accurate under specific conditions. After making a survey of these distributions, we compare them according to both their accuracy and computational cost. Rules are suggested for choosing between Gaussian approximations, compound Poisson approximation, and exact distribution. This work is illustrated with the detection of exceptional words in the phage Lambda genome.

Bacteriophage lambda↗

PubMed2001

Iron concentrations in human dermis assessed by microdialysis associated with atomic absorption spectrometry.

Until recently, the determination of metallic elements concentrations in normal skin, in vivo, was rare due to the lack of non-invasive techniques. Microdialysis has the advantage of being slightly invasive when applied to the collection in vivo of endogenous or exogenous substances from the skin. Iron is an active element in different cutaneous disorders. The aim of this work was to assess iron by atomic absorption spectrometry (AAS) after the collection of samples by microdialysis from human dermis. A first essential step, before determining the in vivo iron concentration in human dermis, was to establish an experimental protocol applicable to ex vivo as well as in vivo conditions. For this reason, this work deals only with the assessment of iron in ex vivo human dermis. A skin microdialysis technique and a calibration method, the No Net Flux, were used to quantify basal iron concentrations in human dermis and the same method was also used to determine in vitro and ex vivo iron recoveries. No differences were detected between in vitro and ex vivo recoveries. Ex vivo basal iron dermis concentrations ranged from 3.6 to 7.7 microg/l. This study shows that non-invasive microdialysis is an efficient method for sampling iron from human skin. A sensitive and accurate AAS technique was able to assess low iron concentrations in human dermis. The strategy adopted for this work was efficient and appropriate for the determination of iron in human skin and experiments will be carried out in vivo.

Dermis↗

PubMed2001

Aerosolized iloprost in CREST syndrome related pulmonary hypertension.

OBJECTIVE: To assess the outcome of patients with CREST syndrome associated severe pulmonary hypertension treated by aerosolized iloprost in a noncomparative study. METHODS: Five patients with CREST syndrome associated severe pulmonary hypertension were treated with 100 microg/day of aerosolized iloprost. New York Heart Association functional class and exercise tolerance (6 min walk test) were assessed at baseline, after one month, and then every 6 months. A right heart catheterization was performed at baseline in all but one patient. Systolic pulmonary artery pressure (PAP) was measured with Doppler echocardiography after one month and every 6 months. RESULTS: The mean followup was 13.2 +/- 8.8 months (median 6, range 6-24). Subjective quality of life improved in all patients. NYHA functional class decreased from Class III to II in 3 patients, from Class III to I in one patient, and from Class IV to III in one patient. At 6 months, the distance walked in 6 min had increased from 352 +/- 48 to 437 +/- 56 m (p = 0.06). At one month the mean systolic PAP was 58 +/- 13 vs 81 +/- 9 mm Hg at baseline (p = 0.04). At 6 months the mean systolic PAP was 57 +/- 13 mm Hg (p = 0.06). The improvement of both clinical and hemodynamic status was maintained in the 2 patients treated for 2 years. Neither adverse effects nor need to increase the daily dose of iloprost were observed. One patient died of right heart failure and one patient did not experience any improvement of exercise tolerance and hemodynamics. CONCLUSION: Aerosolized iloprost might be potentially useful as treatment for CREST syndrome associated pulmonary hypertension. However, patients who could benefit from this treatment will probably have to undergo careful criteria selection.

Administration, Inhalation↗

PubMed2001

[Perceived health survey of 3,800 French adolescents: methodological aspects].

An epidemiological survey was carried out by a local association network and was developed in partnership with regional and national institutions. The survey on well-being and health was conducted over an 18-month period in the French department of Charente. The purpose of the research was to test the hypothesis that "the change in context that is experienced by adolescents at the end of junior high school and at the beginning of high school leads to an increase in risky behaviours". To this end, the survey questioned 3,800 young people on a random basis, mixing those from different grades, those participating in vocational training and apprenticeships, and those from public and private schools. The accomplishment of this survey was made possible thanks to the motivation of a pre-existing strong local network organised and linked to education professionals, the technical contribution of the region's health observatory who conducted the statistical analysis of the data, and the assistance of Unit 472 of the French Institute of Health and Medical Research who provided scientific supervision and advice. The high participation rate and quality of the data (comparable with and even better than some existing studies) demonstrate that it is possible for local associations to carry out effective epidemiological surveys based on the needs keenly felt by the workers themselves, within the scope of a reasonable budget and in a short time span without sacrificing the precision demanded by the scientific method.

Adolescent↗

PubMed2000

Symptomatic hyperlactataemia: an emerging complication of antiretroviral therapy.

BACKGROUND: Fatal lactic acidosis is a serious complication of therapy with nucleoside analogues. OBJECTIVE: To examine symptomatic hyperlactataemia in HIV-infected adults treated with antiretroviral drugs. METHODS: In this prospective study, arterial blood lactate levels were measured in patients presenting with unexplained clinical symptoms. When these levels were high, functional respiratory tests (FRT) were carried out. Liver or muscle biopsies were further proposed. Incidences were calculated by comparison with the entire cohort of patients treated in the department. RESULTS: Fourteen HIV-infected adults treated with antiretroviral drugs were identified with symptomatic hyperlactataemia during a 2-year period follow-up study. The incidence of hyperlactataemia was 0.8% per year but reached 1.2% if only patients treated with a regimen including stavudine were considered. Clinical symptoms included abnormal fatigue, tachycardia, abdominal pain, weight loss, peripheral neuropathy, and more specifically exercise-induced dyspnoea occurring despite effective antiretroviral treatment. FRT showed a metabolic deviation towards anaerobiosis with a high lactate/pyruvate ratio. Ultrastructural mitochondrial abnormalities were seen in all four patients for whom this was examined. There was a marked decrease in complex IV activity in muscle biopsies from four of five patients, consistent with a mitochondrial dysfunction. Evolution was favourable in 13 patients, probably because of an early diagnosis. CONCLUSIONS: Potentially fatal adverse events occurring during antiretroviral treatment may be avoided by close monitoring of clinical signs and blood lactate levels. If other studies confirm that the cumulative long-term toxicity of antiretroviral drugs results from mitochondrial dysfunction, the incidence of hyperlactataemia and its clinical consequences may become more important.

Acidosis, Lactic↗