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Biomedical subjects

C Simon

Publications and source records attributed to C Simon.

At least 37 records · Page 2Linked to original sources
PubMed2005

[How to prescribe physical activity in clinical practice?].

Accumulating scientific evidence indicates that regular physical activity confers significant health benefits. Besides its preventive interest, its promotion is an effective approach of several health problems, including obesity and type 2 diabetes. Its clinical prescription is based on two complementary approaches aimed to decrease sedentary behaviours and/or to promote an active lifestyle with long-term objectives. Physicians can play a key role in motivating patients by advising them regarding their physical limitations, their goals, their concerns, and the barriers to exercise. Assessment of the patient's attitudes and motivation towards physical activity is a key element for the success. Objectives, clearly defined, should be evaluated and adapted on a regular basis, with the patient and taking into account the familial and social environment.

Attitude↗
PubMed2004

Quantum entanglement of a large number of photons.

A bipartite multiphoton entangled state is created through stimulated parametric down-conversion of strong laser pulses in a nonlinear crystal. It is shown how detectors that do not resolve the photon number can be used to analyze such multiphoton states. Entanglement of up to 12 photons is detected using both the positivity of the partially-transposed density matrix and a newly derived criteria. Furthermore, evidence is provided for entanglement of up to 100 photons. The multiparticle quantum state is such that even in the case of an overall photon collection and detection efficiency as low as a few percent, entanglement remains and can be detected.

Journal Article↗
PubMed2004

Effects of increased training load on vagal-related indexes of heart rate variability: a novel sleep approach.

There is little doubt that moderate training improves cardiac vagal activity and thus has a cardioprotective effect against lethal arrhythmias. Our purpose was to learn whether a higher training load would further increase this beneficial effect. Cardiac autonomic control was inferred from heart rate variability (HRV) and analyzed in three groups of young subjects (24.5 +/- 3.0 yr) with different training states in a period free of stressful stimuli or overload. HRV was analyzed in 5-min segments during slow-wave sleep (SWS, a parasympathetic state that offers high electrocardiographic stationarity) and compared with data collected during quiet waking periods in the morning. Sleep parameters, fatigue, and stress levels checked by questionnaire were identical for all three groups with no signs of overtraining in the highly trained (HT) participants. During SWS, a significant (P <0.05) increase in absolute and normalized vagal-related HRV indexes was observed in moderately trained (MT) individuals compared with sedentary (Sed) subjects; this increase did not persist in HT athletes. During waking periods, most of the absolute HRV indexes indistinctly increased in MT individuals compared with controls (P < 0.05) but did not increase in HT athletes. Normalized spectral HRV indexes did not change significantly among the three groups. Heart rate was similar for MT and Sed subjects but was significantly (P <0.05) lower in HT athletes under both recording conditions. These results indicate that SWS discriminates the state of sympathovagal balance better than waking periods. A moderate training load is sufficient to increase vagal-related HRV indexes. However, in HT individuals, despite lower heart rate, vagal-related HRV indexes return to Sed values even in the absence of competition, fatigue, or overload.

Adult↗
PubMed2004

Endothelial cell markers and the risk of coronary heart disease: the Prospective Epidemiological Study of Myocardial Infarction (PRIME) study.

BACKGROUND: Tissue factor pathway inhibitor (TFPI), von Willebrand factor (vWF), and thrombomodulin (TM) are 3 major hemostatic regulatory molecules synthesized by endothelium. Data from epidemiological studies aiming to evaluate the relation between plasma levels of these molecules and the development of coronary heart disease (CHD) are sparse or contradictory. METHODS AND RESULTS: We examined the association between these endothelial-cell markers and the incidence of fatal or nonfatal myocardial infarction (hard CHD) and stable or unstable angina (angina pectoris) in a prospective cohort (the PRIME Study) of nearly 10 000 healthy men recruited in France and Northern Ireland. We measured baseline plasma concentration of the free form of TFPI (f-TFPI), vWF, and the soluble form of TM (sTM) among 296 participants who subsequently developed CHD over the 5-year follow-up (158 with hard CHD and 142 with angina pectoris) and in 563 control subjects by use of a nested case-control design. Individuals with plasma vWF levels in the highest quartile showed a 3.04-fold increase in the risk of hard CHD compared with those in the lowest quartile (95% CI, 1.59 to 5.80). Individuals with f-TFPI levels below the 10th percentile had a 2.13-fold increased risk of hard CHD compared with those with levels above it (95% CI, 1.08 to 4.18). The risk for both molecules persisted after control for inflammatory parameters. Individuals with vWF levels in the highest quartile and f-TFPI levels below the 10th percentile presented a 6.9-fold increased risk of hard CHD compared with those with vWF levels in the lowest quartile and f-TFPI levels above the 10th percentile (95% CI, 1.3 to 37.8). CONCLUSIONS: vWF and f-TFPI plasma levels were independent risk factors for hard CHD events.

Angina Pectoris↗
PubMed2004

Staged informed consent for a randomized clinical trial in childhood leukemia: impact on the consent process.

BACKGROUND: Children Cancer Group (CCG) 1991 is the first childhood acute lymphoblastic leukemia trial within CCG that allowed the utilization of a staged approach to the consent process. METHODS: One hundred and forty subjects participated in the Project on Informed Consent which compared the primary outcome measures in the consent process of patients enrolled in CCG-1991 with those enrolled in other CCG leukemia studies. RESULTS: The parents' trust scores were higher for the CCG-1991 compared with other protocols. Eighty percent of parents enrolled in CCG-1991 understood the distinction between the randomized clinical trial and the standard treatment arm, compared with 62.5% in the other studies, P = 0.05. Multiple other outcome measures suggested a positive impact from staged informed consent. CONCLUSIONS: Our results suggest that a consent process with a staged approach can help investigators obtain a more truly informed consent. Future research is needed to confirm the benefits of the staged approach to the informed consent process.

Child↗
PubMed2004

Sympathovagal response to orthostatism in overt and in subclinical hyperthyroidism.

Heart rate variability (HRV) is a measure of the physiological variation of R-R intervals, reflecting the sympathovagal balance. In both overt and subclinical hyperthyroidism, a relative increase in sympathetic activity has been demonstrated, mainly due to a decrease in vagal activity. The modifications of HRV during orthostatism in normal subjects resemble those seen in hyperthyroidism. We have studied the response of 19 patients with overt hyperthyroidism and 12 with subclinical hyperthyroidism during orthostatism using HRV and compared the results to those of 32 healthy controls. In the three groups, the R-R intervals decreased in the same proportion after orthostatism. The low frequency power (LF)/[LF + high frequency power (HF)] ratio, which reflects the sympathetic tone, also increased in the same proportion in the three groups. However, the mechanisms of the modulation of the sympathovagal balance during orthostatism were different among the three groups. In controls, the relative increase of sympathetic tone after orthostatism was due principally to a decrease in vagal tone (reflected by decreased power in the HF band), while in overt hyperthyroidism, where the power in the HF band was already minimal in the lying position, there was a clear increase in the LF band power during orthostatism. The results were intermediate in the subclinical hyperthyroidism group, reflecting a continuum of effects of the thyroid hormone excess on the autonomic nervous system. Our study shows that despite an apparent normal cardiovascular adaptation to orthostatism in hyperthyroidism, the modulation of the autonomic nervous system is profoundly modified.

Adult↗
PubMed2004

Abnormal heart rate variability in a subject with second degree atrioventricular blocks during sleep.

OBJECTIVE: We compare the profiles of heart rate variability (HRV) during sleep stages in 9 healthy controls and one subject with second degree atrioventricular blocks (AVB), investigating the role of sympathovagal balance in such pathology. METHOD: Sleep and cardiac records were taken for one night in 9 male subjects from 21:00 to 07:00 h and for two nights in a male subject with AVB. Time and frequency domain indexes of HRV were calculated over 5 min-periods. RESULTS: In one subject without any daytime heart disease, 253 and 318 AVB of type 2 (Mobitz 2) were observed during the two experimental nights, predominantly during rapid eye movement (REM) sleep and the surrounding sleep stage 2 in the second half of the night. In the 9 control subjects, absolute HRV indexes and low frequency (LF)/(LF+high frequency, HF) (where LF and HF are low frequency and high frequency power) were low during slow wave sleep, and significantly increased during REM sleep and the preceding sleep stage 2. In the subject with AVB, these HRV indexes were abnormally low during all sleep stages, with a predominant increase in parasympathetic activity as inferred from low LF/(LF+HF). During wake, however, LF/(LF+HF) normally increased, and the tachycardia observed with the arousal that terminates SWS was preserved in the subject with AVB. CONCLUSION: These results suggest that in the subject with second degree atrioventricular blocks, sleep processes, particularly during REM sleep, create a specific neurological background that prevents an increase in sympathetic tone and triggers cardiac pauses.

Adult↗
PubMed2004

Retrospective study of laparoscopic adjustable silicone gastric banding for the treatment of morbid obesity: results and complications in 127 patients.

OBJECTIVES: Laparoscopic gastric banding is currently the most popular surgical technique for morbId obesity. This wIdespread use of surgery has been evaluated by a number of clinical studies, particularly on weight change. METHODS: In a retrospective study of 127 obese patients operated between 1996 and 2000, data were collected for weight change, medical and surgical complications. RESULTS: Of 127 patients, failures of gastric banding were noted during 2 surgical operations. The average follow-up period was 33 +/- 20 Months. Average weight loss in all patients was 19.9 +/- 5.3 kg (15.3 +/- 4.2%). No difference in weight loss was observed between diabetic and non-diabetic patients. During the follow-up, data were collected on 53 complications (42.4% of all gastric banding operations). 3 main types of complication were found: access port related complications (22.6% of the total), band slippage (20.7% of the total) and tubing related complications (16.9% of the total). No prognostic factor for these complications could be Identified from multivariate analysis. CONCLUSIONS: Our results are very similar to those of other weight evolution studies. We found that there was a significant incIdence of surgical and medical complications during the follow-up because of the meticulous way all complications were recorded, even the most insignificant. This morbIdity must be borne in mind before surgery is performed.

Adult↗
PubMed2004

Parent-child physical activity relationships in 12-year old French students do not depend on family socioeconomic status.

OBJECTIVES: Regular physical activity (PA) in young needs to be promoted to prevent obesity and subsequent diabetes. Influences of parental PA on adolescents' activity level have been studied with discordant results and the effect of socioeconomic status (SES) on these relationships is not clarified. METHODS: Cross-sectional population-based survey of about 3000 12-year old French students and their parents. Familial associations were assessed with logistic regression models taking into account SES and children's and parents' corpulence. Sport involvement and sedentary behaviors were assessed by standardized questionnaires filled out separately by children and parents, the latter also reporting their educational data and family income tax. RESULTS: Participation in structured PA outside school was higher for boys (74%) than for girls (58%, p<10-5) and a high sedentary behavior (watching television, playing computer/video games and reading > or =2h/day) was observed in one-third of the sample, both in boys and in girls. Children were more likely to participate in structured PA outside school when both parents practiced sport as compared to neither parent practicing it, with an odd ratio OR (95%CI) of 1.97 (1.4-2.8) for boys and 1.56 (1.2-2.1) for girls. Familial associations of inactivity were significant for boys only. A greater percentage of adolescents had a high level of sedentary behavior when both parents versus no parents watched television > 2h/day (OR 1.95 (1.52.6)). Parent-child physical activity relationships were not modified by the family SES or the children's or parents' weight status. CONCLUSION: Parental involvement in sport is an important correlate of a young adolescent's participation in structured PA outside school, whatever the family SES or corpulence of the family members.

Adolescent↗
PubMed2004

Nutritional intakes of 1072 French free-living men with and without diagnosed cardiovascular risk factors.

OBJECTIVE: To compare the dietary intakes of free-living people with and without previously diagnosed diet-modifiable cardiovascular risk factors (hypertension, hypercholesterolaemia and diabetes). DESIGN: Cross-sectional survey on cardiovascular risk factors including a three-consecutive-day food record. SETTING: Multicentre setting in Lille (northern France), Strasbourg (north-east) and Toulouse (south-west) areas. SUBJECTS: A total of 1072 middle-aged men randomly selected from the general population: group 1 (504 men without previously diagnosed diet-modifiable risk factor), group 2 (377 men with one previously diagnosed diet-modifiable risk factor) and group 3 (191 men with two or three previously diagnosed diet-modifiable risk factors). INTERVENTIONS: None. RESULTS: Total daily energy intake equalled 10731 kJ/day (standard error: 119), 9991 (138) and 9737 (166) in groups 1, 2 and 3, respectively (P<0.0001 for ANOVA comparing the three groups), and daily energy intake without alcohol equalled 9860 (115), 9096 (132) and 8654 (159) kJ/day (P<0.0001). The proportion of calories from animal proteins (in daily energy intake without alcohol) increased from group 1 to 3 (P<0.0001), whereas the proportion from oligosaccharides decreased (P<0.0001). The proportion of calories from alcohol (in total daily energy intake) increased with the number of risk factors (P<0.0001). These results remained significant after adjustment for confounders. No significant group differences were found in the proportions of energy from polysaccharides, saturated, monounsaturated and polyunsaturated fats. CONCLUSIONS: As compared with subjects without risk factor, significant quantitative and qualitative changes are observed in individuals with diagnosed hypertension, hypercholesterolaemia or diabetes. However, lower consumptions of saturated fats and alcohol are needed.

Alcohol Drinking↗
PubMed2004

Intervention centred on adolescents' physical activity and sedentary behaviour (ICAPS): concept and 6-month results.

OBJECTIVE: To evaluate the 6-month impact of a physical activity (PA) multilevel intervention on activity patterns and psychological predictors of PA among adolescents. The intervention was directed at changing knowledge and attitudes and at providing social support and environmental conditions that encourage PA of adolescents inside and outside school. SUBJECTS AND DESIGN: Randomised, controlled ongoing field trial (ICAPS) in middle-school's first-level adolescents from eight schools selected in the department of the Bas-Rhin (Eastern France) with a cohort of 954 adolescents (92% of the eligible students) initially aged 11.7+/-0.6 y. The 6-month changes in participation in leisure organised PA (LOPA), high sedentary (SED) behaviour (>3 h/day), self-efficacy (SELF) and intention (INTENT) towards PA were analysed after controlling for baseline measures and different covariables (age, overweight, socioprofessional occupation), taking into account the cluster randomisation design. RESULTS: The proportion of intervention adolescents not engaged in organised PA was reduced by 50% whereas it was unchanged among control students. After adjustment for baseline covariables, LOPA participation significantly increased among the intervention adolescents (odds ratio (95% confidence interval) (OR)=3.38 (1.42-8.05) in girls; 1.73 (1.12-2.66) in boys), while high SED was reduced (OR=0.54 (0.38-0.77) in girls; 0.52 (0.35-0.76) in boys). The intervention improved SELF in girls, whatever their baseline LOPA (P<10(-4)) and INTENT in girls with no baseline LOPA (P=0.04). SELF tended to improve in boys with no baseline LOPA, without reaching statistical significance. When included in the regression, follow-up LOPA was associated with improvement of SELF in girls (P=0.02) and of INTENT in girls with no baseline PA (P<0.02). The intervention effect was then attenuated. CONCLUSION: After 6 months of intervention, ICAPS was associated with a significant improvement of activity patterns and psychological predictors, indicating a promising approach for modifying the long-term PA level of adolescents.

Adolescent↗
PubMed2004

Early colonoscopy in patients with acute diverticulitis: results of a prospective pilot study.

BACKGROUND AND STUDY AIMS: Outcomes following early colonoscopy in patients with acute diverticulitis have not previously been studied. The present study describes the effects of early colonoscopy in patients with acute diverticulitis. PATIENTS AND METHODS: Consecutive patients hospitalized for acute diverticulitis were included in the study. In the first phase, patients with adjacent peridiverticular air or fluid on computed tomography (CT) were excluded. In the second phase of the study, only patients with free intraperitoneal air were excluded. RESULTS: The study population consisted of 107 patients. During the first phase of the study, 49 patients were included; 10 were excluded because of peridiverticular air or fluid. The remaining 39 patients underwent uneventful colonoscopy. During the second phase of the study, 58 patients were included; four were excluded because of free air in the peritoneum. The remaining 54 patients underwent colonoscopy, and perforation of the sigmoid colon occurred in one patient with peridiverticular air. Complete colonoscopy to the cecum or to the obstructing tumor was achieved in 76 patients (81.7 %). A second colonoscopy performed 6 weeks later in 16 of the remaining 17 patients was successfully completed. Findings during the first colonoscopy were polyps in nine cases, polyp with infiltrating adenocarcinoma in one, obstructing adenocarcinoma in one, and a bone trapped in a diverticulum in another one. The latter two patients had a more protracted course and were clearly the ones who benefited most from the colonoscopy. CONCLUSIONS: Early colonoscopy in patients with acute diverticulitis may alter the working diagnosis and be of therapeutic value. The rate of cecal intubation is lower and the perforation rate appears to be higher. A clear-cut indication therefore has to be evident clinically.

Adenocarcinoma↗
PubMed2004

Effect of acute hypoxia on heart rate variability at rest and during exercise.

The purpose of this study was to investigate sympathovagal balance as inferred from heart rate variability (HRV) responses to acute hypoxia at rest and during exercise. HRV was evaluated in 12 healthy subjects during a standardized hypoxic tolerance test which consists of four periods alternating rest and moderate exercise (50 % V.O (2)max) in normoxic and hypoxic conditions. Ventilatory responses were determined and HRV indexes were calculated for the last 5 min of each period. In well-tolerant subjects, hypoxia at rest induced a decrease of root-mean-square of successive normal R-R interval differences (RMSSD) (p < 0.05) and of absolute high frequency (HF) power (p < 0.001). All absolute HRV indexes were strongly reduced during exercise (p < 0.001) with no further changes under the additional stimulus of hypoxia. A significant increase (p < 0.05) in the HF/(LF+HF) ratio (where LF is low frequency power) was found during exercise in hypoxia compared to exercise in normoxia, associated with similar mean changes in ventilation and tidal volume. These results indicate a vagal control withdrawal under hypoxia at rest. During exercise at 50 % V.O (2)max, HRV indexes cannot adequately represent cardiac autonomic adaptation to acute hypoxia, or possibly to other additional stimuli, due to the dominant effect of exercise and the eventual influence of confounding factors.

Adaptation, Physiological↗
PubMed2004

Secondary structure, high variability and conserved motifs for domain III of 12S rRNA in the Arthropleona (Hexapoda; Collembola).

The robustness of different hypothetical structural models for ribosomal RNAs can be established by comparing sequences from widely different taxonomic groups. Secondary structure models of the two mitochondrial ribosomal subunits have been proposed for a large number of pterygote insects, but little information is available for the more ancient entognath hexapods. We have investigated the most frequently sequenced of the four domains of the mitochondrial small subunit rRNA in twenty-two collembolan species in the taxon Arthropleona. We provide secondary structure models of this third domain for representative species, and a consensus based on all species studied. This consensus is in partial agreement with previous models. High levels of variation, in terms of length and of primary sequence, are present in the peripheral portions of the domain. Some of the structural elements differ more among genera of springtails than among insect orders. Conversely, a limited number of structural differences compared with other taxa have been detected in the core regions.

Animals↗
PubMed2004

Effect of activators and the phosphodiesterase inhibitors pentoxifylline and enoximone on the deformability of neutrophils in neonates and adults.

BACKGROUND: Stimulated polymorphonuclear leukocytes (PMN) are extremely rigid compared to resting PMN. They may obstruct narrow vessels and contribute to ischaemic organ injury. Deformability is a prerequisite for both active and passive movement in the microcirculation. AIM: The investigation was designed to study whether stimulators and inhibitors of stimulation show different effects on deformability of neonatal and adult PMN. METHODS: Deformability of PMN was assessed by complete aspiration of a PMN into a micropipette with an internal diameter of 5 microm. Blood samples from 20 neonates and 20 adults were studied before and after stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP), interleukin-8 (IL-8) or tumour necrosis factor-alpha (TNF-alpha). Moreover, effects of the phosphodiesterase inhibitors Pentoxifylline (PTX) and Enoximone on the deformability of stimulated PMN were investigated. RESULTS: fMLP, IL-8 and TNF-alpha significantly delayed aspiration times of PMN in relation to the concentrations of the stimulators. The addition of PTX or Enoximone to stimulated PMN increased the deformability up to 60% depending on the concentration of the inhibitors. No significant differences in the aspiration times were found between neonatal and adult PMN at any of the experimental conditions after activation with the three stimulators and treatment with the two inhibitors. CONCLUSION: Neonatal and adult PMN show similar reduction of passive deformability when stimulated with either fMLP, IL-8 or TNF-alpha compared to resting PMN and a similar improvement of deformability in response to PTX or Enoximone.

Adult↗
PubMed2003

The chemokine connection: hormonal and embryonic regulation at the human maternal-embryonic interface--a review.

Chemokines are small polypeptides that attract specific leukocyte subsets by binding to cell-surface receptors. In reproductive biology, they have been implicated in ovulation, menstruation, and embryo implantation, and pathological processes such as preterm delivery, HIV infection, and endometriosis. It is known that successful implantation requires a functionally normal embryo at the blastocyst stage and a receptive endometrium that is adequately communicated through the implantation process. This crosstalk is highly regulated, with numerous molecules taking part. Accumulated evidence suggests that chemokines produced and received by the endometrial epithelium and the human blastocyst are implicated in this molecular network. Here, we present updated information on the presence and hormonal and embryonic regulation of chemokines and their receptors during human implantation.

Adult↗