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Biomedical subjects

C Simon

Publications and source records attributed to C Simon.

At least 19 recordsLinked to original sources
PubMed2006

Habitual physical activity, physical fitness and heart rate variability in preadolescents.

The amount and type of physical activity (PA) appropriate in youth for optimal health is still being discussed. The purpose of this study on 12-year-old preadolescents is to evaluate the association of two PA patterns, corresponding to different exercise intensities, with some health-related indexes. PA was evaluated by triaxial accelerometry in 67 student subjects, who were successively classified according to 1) their usual participation or not in moderately intense (> 4 metabolic equivalents, METs) activities (either in daily life or in leisure activities) for at least 210 min a week (4 M (210)); and 2) the habitual practice or not of more intense activities (> 6 METs) for at least 60 min a week (6 M (60)). Health-related indexes consisted of cardiopulmonary (maximum oxygen uptake, V.O 2max), muscular (lower limb strength) fitness parameters and vagal-related indexes of heart rate (HR) variability (HRV), such as the HF/(LF+HF) ratio (where HF and LF stand for high and low frequency power). HR was recorded in the supine position after 15 min of quiet rest, and HRV indexes were calculated in 5-min segments. Energy expenditure due to PA was not significantly associated with any health-related index. Reaching 4 M (210) was associated with both higher estimated V.O 2max (p < 0.05) and higher muscular strength indexes (p < 0.05) but not with enhanced HRV indexes. Subjects who reached 6 M (60) had higher estimated V.O2max (p < 0.05) and higher HF/(LF+HF) (p < 0.05). Our results show that regular moderately intense activities are sufficient to influence physical fitness but suggest that more intense activities are necessary to observe more favorable HRV vagal-related indexes.

Child↗
PubMed2006

Cigarette smoking affects uterine receptiveness.

BACKGROUND: Cigarette smoking has long been known to have an effect on female fertility. The existence of an ovarian factor is clear when one considers that the mean age of the menopause is lower and IVF cycle outcome is worse in heavy smokers. The hypothesis of a concomitant uterine effect is raised by indirect evidence from in vitro and in vivo studies, but as yet, no direct evidence has been gained to confirm its existence. In this work, we analyse the association between smoking habit in oocyte recipients and cycle outcome. METHODS: We have retrospectively analysed the outcome of all oocyte donation cycles performed in our clinic from January 2002 to June 2005 from which there was available information regarding patient current smoking status. Husband and donor smoking status were controlled variables, as well as donor and recipient age, patient body mass index, embryo number and quality and duration of endometrial priming. RESULTS: Pregnancy rate (PR) in non-heavy smokers (0-10 cigarettes/day) was significantly higher than in heavy smokers (>10 cigarettes/day) (52.2 versus 34.1%, respectively). Interestingly, multiple PR was significantly higher in heavy smokers (60 versus 31%). CONCLUSION: Tobacco consumption determines reduced uterine receptiveness and an increased risk of multiple pregnancies. This last issue remains to be clarified.

Abortion, Spontaneous↗
PubMed2006

Relationships of physical activity with metabolic syndrome features and low-grade inflammation in adolescents.

AIMS/HYPOTHESIS: Physical activity has beneficial effects on symptoms of the metabolic syndrome and low-grade inflammation in adults. These associations have rarely been studied in adolescents. Moreover, it has not been established whether they depend on adiposity, fat localisation and adipokines. SUBJECTS, MATERIALS AND METHODS: We used cross-sectional data of 640 12-year-old adolescents participating in the Intervention Centred on Adolescents' Physical Activity and Sedentary Behaviour Study (ICAPS). Weight, height, body fat mass and WHR were measured. Metabolic syndrome components, two inflammatory markers (IL-6 and C-reactive protein), plasma leptin, adiponectin and soluble TNF-alpha receptor 1 (sTNF-alpha R1) were determined. Insulin resistance was estimated by homeostasis model assessment (HOMA) and energy expenditure due to organised leisure-time physical activity (PAE) assessed by questionnaire. RESULTS: The metabolic syndrome was present in 5.8% of the adolescents. After adjustment for sex, sexual maturity and socio-economic status, a beneficial relationship between PAE and all metabolic syndrome features was found, but only the associations with HOMA and IL-6 were independent of body fat mass and WHR. Adjusted means from the lowest to the highest tertile of PAE were 1.99, 1.80 and 1.78 for HOMA (p=0.04), and 0.88, 0.69 and 0.70 pg/ml for IL-6 (p=0.02). PAE was inversely associated with leptin, independently of body fat mass and WHR (p<10(-2)), but not with adiponectin or sTNF-alpha R1. Further adjustment for adipokines did not change the relationships of PAE with HOMA and IL-6. CONCLUSIONS/INTERPRETATION: In adolescents, physical activity is inversely related to HOMA and IL-6, independently of adiposity and fat localisation. These relationships are not accounted for by adipokines.

Adipocytes↗
PubMed2006

Implantation of the human embryo: research lines and models. From the implantation research network 'Fruitful'.

Infertility is an increasing problem all over the world, and it has been estimated that 10-15% of couples in fertile age have fertility problems. Likewise induced unsafe abortion is a serious threat to women's health. Despite advances made in assisted reproduction techniques, little progress has been made in increasing the success rate during fertility treatment. This document describes a wide range of projects carried out to increase the understanding in the field of embryo implantation research. The 'Fruitful' research network was created to encourage collaborations within the consortium and to describe our different research potentials to granting agencies or private sponsors.

Animals↗
PubMed2006

Induction of endometriosis in the marmoset monkey (Callithrix jacchus).

Endometriosis is an estrogen-dependent gynaecological disease associated with pain and infertility, which occurs in humans and menstruating primates. In this study, the marmoset monkey (Callithrix jacchus), which is a non-menstruating primate with high circulating estrogen levels, was used to test firstly the hypothesis that endometriosis is based on uterine shedding into the peritoneal cavity, secondly to study the pathogenesis of endometriosis due to its estrogenic situation. Female marmoset monkeys (n = 29) were exposed to two different experimental procedures (non-invasive versus invasive) for intrapelvic placement of endometrial cells by uterine flushing over an experimental period of 2-3 years. First endometriotic foci were detected by colour Doppler ultrasound at the bladder, the uterus and the ovaries at the earliest after 4 months of either treatments. However, invasive induction was more effective in terms of the time-course of induction and the number of resulting endometriotic foci. The analysis of the endometriotic foci by histology, immunohistochemistry and molecular techniques allowed a division into two distinct groups: an initial developing stage occurred, which under further treatment led to the second stage of established endometriosis. Both procedures showed a treatment-dependent increase of vascular supply to the endometriotic foci over the experimental period. The invasive method induced the final established stage of endometriosis more rapidly, with the expression of steroid receptors, aromatase, 17betaHSD1 and CD10. Altogether, 72% of the treated marmoset monkeys developed endometriosis under our endometrial reflux protocols. Our data support the theory that endometriosis can be induced artificially in a non-menstruating primate (C. jacchus) by endometrial shedding into the peritoneal cavity. Because the marmoset is a primate with very high peripheral estrogen levels, this offers an interesting model for studying the pathogenesis of this estrogen-dependent disease, as well as for therapeutic impacts on enzymes involved in steroid metabolism.

17-Hydroxysteroid Dehydrogenases↗
PubMed2006

Molecular dynamics simulation of hydrogen fluoride mixtures with 1-ethyl-3-methylimidazolium fluoride: a simple model for the study of structural features.

Mixtures of hydrogen fluoride with ionic liquids show unique physicochemical properties, including their ability to form polyfluoride species (pointed out for the first time in this media by von Rosenvinge et al. J. Chem. Phys. 1997, 107, 8012). Among those systems the acidic 1-ethyl-3-methylimidazolium fluoride (EMIF.2.3HF) has been widely studied experimentally since it is the more promising for electrochemical applications. Recent studies (Hagiwara et al. J. Electrochem. Soc. 2002, 149, D1), while yielding many results, raised some questions about structural features of the liquid: absence of hydrogen bonds between the EMI+ ring hydrogen atoms and the fluoride anions, persistence of stacks and layers of cations similar to those existing in the crystal, and interpretation of the X-ray diffraction spectra. To address these questions, we have developed a simple molecular dynamics model. Our simulations are very consistent with experimental results and complete them, providing an atomic scale interpretation.

Journal Article↗
PubMed2006

[Complex proximal humerus fractures--management with a humeral head prosthesis? Clinical and radiological results of a prospective study].

BACKGROUND: Proximal humerus fractures are one of the most common fractures in elderly patients. In the treatment of complex proximal humerus fractures, primary hemiarthroplasty is still discussed controversially. The present study was undertaken to evaluate the results of primary hemiarthroplasty in the treatment of proximal humerus fractures with a modular prosthesis (EPOCA, Fa. Argomedical, Gifhorn, Germany). MATERIAL AND METHODS: A prospective study of 24 patients with complex humerus fracture (NEER: IV/4, V/4, VI/4, and head split fracture) was performed from August 2000 to December 2002. Mean age was 75.6 years (range: 52-92); 18 patients were seen for follow-up after 0.5 and 1 year, respectively. The Constant-Murley score (max. 100 points) and the UCLA Rating System (max. 35 points) were calculated for functional assessment of the operated shoulder. RESULTS: Fifteen patients (83%) were pain free 1 year after the operation. The Constant-Murley score improved from 52 (+/-17) to 56 (+/-18) at the second follow-up after 1 year. On the contralateral side a score of 86 (+/-10) was assessed (p<0.05 vs operated side). Correspondingly, shoulder function according to the UCLA Rating System improved [25 (+/-4); 27 (+/-5)]. CONCLUSIONS: Osteoporotic bone of older patients often may not permit stable internal fixation of complex proximal humerus fractures. In these situations primary hemiarthroplasty is the treatment of choice.

Aged↗
PubMed2006

ICAPS: a multilevel program to improve physical activity in adolescents.

OBJECTIVES: ICAPS (Intervention Centred on Adolescents' Physical activity and Sedentary behaviour) is aimed at preventing excessive weight gain and cardiovascular risk in adolescents by promoting physical activity (PA) with an emphasis on recreational and daily-life PA, with a lifelong perspective. DESIGN: Randomized study designed to last for four years. Study cohort constituted of 954 first-level students (91% of eligible pupils), aged 11.7 +/- 0.6 y (mean +/- SD) from four pairs of schools randomly selected in eastern France, after sociogeographical stratification. In each pair, intervention status was randomised at school-level. The program, not limited to school settings, involves multiple partners with three objectives: 1) changing attitudes through debates and access to attractive activities during breaks and after-school hours, 2) encouraging social support, 3) providing environmental conditions that enable PA. Adapted times and places, open participation, emphasis on fun, meeting with others and absence of competitive aspects are used to reduce usual barriers to PA. Accessibility and safety are permanent concerns. RESULTS: Prevalence of overweight was 23.7%. High participation rates were attained (50% participated in at least one weekly activity). At six-month, the proportion of intervention adolescents not performing supervised PA out of academic PA was reduced by half (36% to 17% vs 42% to 42% in controls P < 10-4); the proportion of those spending > 3 h/day in sedentary occupations decreased (34% to 28% vs 27% to 36%; P < 10-4). CONCLUSION: These data demonstrate the feasibility of implementing a multilevel PA intervention program in adolescents. Six-month results document increased PA and decreased sedentary behaviour.

Adolescent↗
PubMed2006

Circulating procoagulant microparticles in obesity.

AIM: Obesity is a risk factor for cardiovascular diseases and venous thromboembolism. Circulating procoagulant microparticles (MP) have been described in various clinical situations associated with thrombosis and in diabetic patients. The aim of this preliminary study was to evaluate the presence of MP in obese patients without any other vascular risk factor in particular diabetes. METHODS: Fifty-eight obese women <50 year-old without other cardiovascular risk factors were recruited from a single out-patient nutrition clinic. They were compared to 45 age-matched healthy normal weight controls. Main outcome was MP levels in patients and controls. Relationships between MP concentrations and parameters reflecting insulin resistance in patients were also studied. RESULTS: Obese patients were 33.3 +/- 1.2 years old and had a mean BMI of 42.4 +/- 0.9 kg/m2. There vas a greater proportion of smokers in the obese group (34.5 vs 15.6%). Mean MP levels were markedly higher in obese patients compared to controls (10.6 +/- 0.5 vs 3.2 +/- 0.3 nMPSeq, P < 0.001). There was no difference in MP concentrations between smokers and non smokers. In the obese group, there was a negative correlation between MP and BMI (r = -0.265, P < 0.05) but no relationship could be established between MP concentrations and markers of insulin resistance. CONCLUSION: This increase in circulating MP levels reflects cell activation and could account for the increased risk of thrombotic complications in obesity. Further studies are ongoing to explore the relationships between MP levels and coagulation markers and to assess the effect of weight reduction.

Adult↗
PubMed2006

Relationship between very high physical activity energy expenditure, heart rate variability and self-estimate of health status in middle-aged individuals.

In middle-aged persons, moderate physical activity energy expenditure (PAEE) has been shown to be associated with increased vagal-related heart rate variability (HRV) indexes and better health status. The purpose of this study was to determine whether a very high PAEE has greater effect on vagal-related HRV indexes and self-estimates of well-being in middle-aged subjects having distinct long-term physical activity profiles. Forty-four subjects were divided into three groups on the basis of the sport score of the Modified Baecke Questionnaire for Older Adults: sedentary (SED, n = 15), moderately-trained (MT, n = 16), and highly-trained subjects (HT, n = 13). PAEE was estimated by triaxial accelerometry during one week. Time and frequency domain HRV indexes were determined during quiet periods in the morning on 5-min R-R interval segments under controlled breathing. Quality of life was evaluated using the SF-36 health survey questionnaire. PAEE was significantly different for each group (374.5 +/- 13.8, 616.8 +/- 22.4, and 1086.6 +/- 43.2 kcal . day (-1) for SED, MT, and HT, respectively, p < 0.001). MT presented significantly higher vagal-related HRV indexes than SED and HT (p < 0.05). None of the HRV indexes was significantly greater in HT than in SED. MT and HT had similar health status scores, which were significantly higher than for SED. These results indicate that in middle-aged subjects, habitual moderate PAEE is associated with greater vagal tone and self-estimates of well-being compared to low PAEE. In contrast, very high PAEE is associated with similar vagal-related indexes as low PAEE, despite better overall health status.

Aging↗
PubMed2006

Leisure-time and occupational physical activity in relation to cardiovascular risk factors and eating habits in French adults.

OBJECTIVE: To investigate the relationships of two main physical activity domains (during leisure and at work) with cardiovascular risk factors and eating habits. DESIGN: Cross-sectional study. SETTING: Preventive medicine centre. SUBJECTS: In 5478 adults (32% women, aged 20-80 years) who consecutively underwent a standardised health examination, leisure-time physical activity (LTPA; i.e. non-sport leisure and sport activities), occupational physical activity (OPA) and eating habits were assessed by self-administered questionnaires. We analysed sex-specific relationships of LTPA and OPA (in quartiles) with (1) various cardiovascular risk factors and (2) eating habits using analysis of variance and logistic regression, respectively. RESULTS: In both genders, with and without adjustment for education in addition to age, LTPA was associated negatively with body mass index, body fat, waist circumference, resting heart rate, diastolic blood pressure and triglycerides, and positively associated with high-density lipoprotein cholesterol (all P < or = 0.005). OPA adjusted for age only was positively associated with most cardiovascular risk factors but these associations were not significant after further adjustment on education (except for waist circumference in women). Age- and education-adjusted LTPA was associated with increased frequency of consumption of fruits (odds ratio (OR) = 2.05, 95% confidence interval (CI) 1.68-2.52 in men; OR = 1.90, 95% CI 1.41-2.05 in women) and vegetables (OR = 1.81, 95% CI 1.48-2.21 in men; OR = 2.22, 95% CI 1.66-2.97 in women). CONCLUSIONS: The data emphasise the favourable associations of LTPA, a modifiable behaviour, with various cardiovascular risk factors and healthy eating habits. The results also suggest that the relationships of OPA with cardiovascular risk factors depend, at least in part, on socio-economic status as reflected by educational level.

Adult↗
PubMed2006

Suprastomal tracheal stenosis after dilational and surgical tracheostomy in critically ill patients.

We have previously reported cases of severe suprastomal stenosis after tracheostomy. In this observational study we investigated the occurrence of suprastomal stenosis as a late complication. Patients with persistent tracheostomy after intensive care underwent an endoscopic examination of tracheostoma, larynx and trachea. A percutaneous dilational tracheostomy was employed in 105 (71.9%) and surgical tracheostomy in 41 (28.1%) of the cases (n = 146). The incidence of severe suprastomal stenosis (grade II > 50% of the lumen) was 23.8% (25 of 105) after dilational tracheostomy and 7.3% (3 of 41) after surgical tracheostomy (p = 0.033). Age, gender, underlying disease, ventilation time, and swallowing ability were not significantly associated with the tracheal pathology. This study suggests that dilational tracheostomy is associated with an increased risk of severe suprastomal tracheal stenosis compared to the surgical technique.

Adult↗
PubMed2005

Similar endometrial development in oocyte donors treated with either high- or standard-dose GnRH antagonist compared to treatment with a GnRH agonist or in natural cycles.

BACKGROUND: This descriptive study evaluates the impact on endometrial development of standard and high doses of a GnRH antagonist in stimulated cycles compared with GnRH agonist and natural cycles. METHODS: Thirty-one oocyte donors were treated with a combination of rFSH and 0.25 mg/day ganirelix (standard dose), 2 mg/day ganirelix (high dose) or 0.6 mg/day buserelin (long protocol). Vaginal progesterone (200 mg/day) was administered in the luteal phase. Endometrial biopsies were performed 2 and 7 days after HCG administration. Additional biopsies were carried out in a subset of 12 subjects, 2 and 7 days following the LH peak of their previous natural cycle. Biopsies were evaluated histologically and by scanning electron microscopy. Gene expression profiles were also studied. RESULTS: At HCG +2, all the parameters studied were similar in all the groups and comparable to those observed in the natural cycle. At HCG +7, endometrial dating, steroid receptors and the presence of pinopodes were comparable in both GnRH antagonist groups and in the natural cycle. In buserelin group, endometrial dating and pinopode expression suggested an arrested endometrial development. For window of implantation genes, expression patterns were closer to those in the natural cycle following standard- or high-dose ganirelix than after buserelin administration. CONCLUSION: No relevant alteration was observed in the endometrial development in the early and mid-luteal phases in women undergoing controlled ovarian stimulation for oocyte donation following daily treatment with a standard- or high-dose GnRH antagonist. In addition, the endometrial development after GnRH antagonist mimics the natural endometrium more closely than after GnRH agonist.

Adolescent↗
PubMed2005

The safety of pegylated interferon alpha-2b in the treatment of chronic hepatitis B: predictive factors for dose reduction and treatment discontinuation.

BACKGROUND: Treatment with interferon-alpha has been shown to be effective in one-third of hepatitis B e antigen-positive chronic hepatitis B patients, but is clinically associated with relevant adverse events. AIM: To investigate the safety of pegylated interferon alpha-2b in 300 hepatitis B e antigen-positive patients with compensated liver disease. METHODS: Patients were treated with pegylated interferon alpha-2b for 52 weeks combined with either lamivudine 100 mg/day or placebo. Pegylated interferon alpha-2b was administered for 100 microg once a week for 32 weeks; thereafter, the dose was reduced to 50 microg once a week. Adverse events and their effect on study medication were reported at monthly visits in a standardized way. RESULTS: The most frequently reported side-effects were flu-like syndrome (68%), headache (40%), fatigue (39%), myalgia (29%) and local reaction at the injection site (29%). These symptoms typically occurred within the first month of therapy and subsided during the course of therapy. Neutropenia and thrombocytopenia induced by pegylated interferon alpha-2b increased the risk of infections and bleeding complications, but these complications were rare and mild. The frequency of all side-effects was not different between patients treated with pegylated interferon alpha-2b combined with lamivudine or placebo. In 69 (22%) patients the dose of pegylated interferon alpha-2b was reduced prematurely. Of these dose reductions, 36 (52%) were because of neutropenia. Therapy was discontinued in 28 (8%) patients. The most frequent reasons for early discontinuation were psychiatric side-effects (depression, psychosis) and flu-like symptoms. Multivariate Cox regression analysis showed that low neutrophil count at baseline and cirrhosis were independent predictors of dose reduction or therapy discontinuation. CONCLUSION: We conclude that in patients with chronic hepatitis B and compensated liver disease prolonged pegylated interferon alpha-2b therapy is safe, and that pre-existent cirrhosis and neutropenia are the most important predictors of dose reduction or early treatment discontinuation.

Adult↗
PubMed2005

Physical activity is inversely related to waist circumference in 12-y-old French adolescents.

BACKGROUND AND OBJECTIVE: Waist circumference (W) has been shown to be a good predictor of cardiovascular risk. The aim of this study was to investigate whether physical activity (PA) is related to W in adolescents as previously shown in adults. DESIGN AND SUBJECTS: Cross-sectional population-based survey of 2,714 12-y-old adolescents from the eastern part of France. MEASUREMENTS: Body mass index (BMI) and W were measured. Structured PA, active commuting to and from school and sedentary activities (SED), for example television viewing, computer/video games and reading and different potential confounders (dietary habits, parental overweight, family annual income tax and educational level) were assessed by a questionnaire. RESULTS: The adolescents had a mean BMI of 19.0+/-3.4 kg/m2, and 20.2% of them were overweight, with no gender difference. Boys had a greater W than girls (67.6+/-9.1 vs 65.7+/-8.9 cm, P<0.0001). In all, 42% of the girls and 25% of the boys did not practice any structured PA outside school and less than 40% of the adolescents commuted actively to school more than 20 min/day. About one-third of the adolescents devoted more than 2 h/day to SED. In univariate analyses, BMI was negatively associated with structured PA but significantly only for girls (P<0.01) and positively associated with SED for both genders (P<0.0001 for girls, P<0.01 for boys). W was negatively associated with structured PA and positively associated with SED both in girls (P<0.0001 and P=0.03, respectively) and boys (P<0.01 and P=0.08, respectively). Multiple general linear models show that SED is associated with BMI, independently of structured PA, in both genders. On the other hand, structured PA was inversely associated with W, independently of SED. The inverse relation between structured PA and W persisted after additional adjustment on BMI, with a greater effect of PA for the adolescents with higher BMI. CONCLUSIONS: In 12-y-old adolescents, structured PA is inversely associated with W, an indicator of total adiposity but also more specifically of abdominal fat. This suggests that PA may have a beneficial effect on youth metabolic and cardiovascular risks, in particular in the presence of overweight..

Abdomen↗