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J Mercier

Publications and source records attributed to J Mercier.

At least 37 records · Page 2Linked to original sources
PubMed2003

The effects of intensive training on insulin-like growth factor I (IGF-I) and IGF binding proteins 1 and 3 in competitive cyclists: relationships with glucose disposal.

The aim of the present study was to determine whether 4 months of intensified training would result in modified plasma insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 1 (IGFBP-1) or IGFBP-3 in eight competitive cyclists and eight sedentary individuals and to define the relationships of these factors with glucose disposal. Insulin sensitivity and glucose effectiveness--that is, the fractional disappearance of glucose independent of any change in insulinaemia--were measured with the minimal model (mathematical analysis of frequently sampled intravenous glucose tolerance test). Both glucose effectiveness and insulin sensitivity were higher in the cyclists than in the sedentary individuals, but did not increase further with training. IGF-I was higher in the cyclists than in the sedentary group only after raining (P < 0.05). Plasma IGFBP-1 and IGFBP-3 increased after training (38 and 20%, respectively; P < 0.05) in the cyclists and were higher than in the sedentary individuals (P < 0.05). IGF-I was negatively correlated with insulin sensitivity before and after training (r = -0.66 and -0.67, respectively; P < 0.05) and IGFBP-1 was negatively correlated with glucose effectiveness before andafter training (r = -0.68 and -0.77, respectively; P < 0.05). Our results show that strenuous endurance training improves the somatotrope axis (growth hormone-IGF) and that IGFBP-1 may be involved in glucose homeostasis, possibly by limiting the exercise-induced increase in glucose disposal, in competitive cyclists.

Adult↗
PubMed2003

[Dental extraction in patients with bleeding disorders. Proposal of a protocol based on the type of anesthesia used].

INTRODUCTION: The authors propose a protocol to avoid bleeding complications in patients with bleeding disorders. MATERIAL AND METHOD: When a general anesthesia or trunk nerve infiltration is indicated, clotting factor concentrates are to be used in patients with severe bleeding disorders. Desmopressin is to be used in patients with mild bleeding disorders but who are good responders and in patients with thrombopathy. An antifibrinolytic treatment and a fibrin glue are also used. Ninety-six patients underwent 107 extractions with this protocol. RESULTS: Only two patients had bleeding complications requiring an additional treatment. DISCUSSION: In case of bleeding disorders, the treatment depends on disease severity and type of anesthesia. A general treatment (clotting factor concentrates or desmopressin) is indicated with general anesthesia and with local anesthesia in severe bleeding disorders, but not absolutely necessary with local anesthesia in mild bleeding disorders. However, desmopressin can used in all good responders.

Adolescent↗
PubMed2003

Is whole body impedance a predictor of blood viscosity?

Bioelectrical impedancemetry (BIA) has received a widespread interest as a non-invasive approach to body fluid volumes. Since similar techniques have been studied to assess in vitro rheological properties of blood, we investigated the relationships between whole body impedance and blood viscosity parameters in order to determine possible predictive equations. 30 sportsmen (24.6+/-1.01 years; 73.96+/-1.62 kg; 177.73+/-1.33 cm) were enrolled into the study. Body composition was assessed with a multifrequency bioelectrical impedancemeter (Dietosystem Human IM Scan) using low intensity at the following frequencies: 1, 5, 10, 50 and 100 kHz. Viscometric measurements were done at 1000 s(-1) with a falling ball viscometer (MT 90 Medicatest). Hematocrit (Hct) was measured with microcentrifuge. A standardized exercise test was performed on a cycloergometer during 25 minutes. Physical working capacity (W170) was calculated and VO2max was evaluated with Astrand nomograms. Two hemorheological parameters were independently correlated with impedance (Z) measurements: whole blood viscosity (WBV) at 100 kHz (r=0.518; p=0.01) and Hct at 1 kHz (r=-0.485; p=0.01). Plasma viscosity was correlated multilinearly with water/fat free mass and Z at 10 kHz (r=0.441; p=0.02). In addition both WBV and Z at 100 kHz exhibited correlations with aerobic working capacity (VO2max ) with r=-0.482 and r=-0.475 (p</=0.05), respectively. A stepwise regression analysis selects Z at 100 kHz instead of WBV as a predictor of VO2max. These findings confirm our previous reports about relationships between whole body conductance for high frequency and aerobic working capacity and suggest a new approach for non-invasive evaluation of blood rheology with BIA.

Adult↗
PubMed2003

Reduction of red blood cell disaggregability during submaximal exercise: relationship with fibrinogen levels.

Effects of exercise on erythrocyte aggregation were investigated in 19 elite athletes. High shear rate viscometry (1000 s(-1) evidenced an increase in blood viscosity explained by an increase in hematocrit (+8% p<0.01) and plasma viscosity (+7% p<0.01). Erythrocyte rigidity index and erythrocyte aggregability measured using the Myrenne erythroaggregometer did not change. However, using the laser backscattering technique (SEFAM erythroaggregometer), we observed significant changes in aggregability and desaggregability after 25 min of exercise. The initial aggregation time (TA) decreased by 33% (p<0.01), while the final aggregation time decreased by 13.6% (p<0.01). TA was correlated with aerobic working capacity (r=0.73; p=0.005), which was negatively correlated with blood viscosity at rest (r=-0.57; p=0.043). A significant relationship was observed between TA and the initial fibrinogen levels (r=0.71; p<0.01). The plasma volume contraction during exercise was found to be statistically explained by the water loss proportional to the total work load. Thus, laser backscattering demonstrates an increase in aggregability and a decrease in disaggregability of red cells during exercise, proportional to baseline fibrinogen values.

Adult↗
PubMed2003

Is the feeling of heavy legs in overtrained athletes related to impaired hemorheology?

The feeling of having "heavy legs" (FHL) is commonly reported in the overtraining syndrome (OTS), i.e., the condition wherein an athlete is training excessively, yet performance deteriorates. Since FHL is also a sign of chronic venous insufficiency where it can be corrected by rheo-active drugs, and given the fact that OTS is also a hemorheologic disease associated with mild hemoconcentration, we investigated whether the FHL is associated with a hemorheologic profile. 37 athletes training 13.05+/-0.97 hr/week completed the French questionnaire of Overtraining (mean score: 11.66+/-1.96) and underwent a medical check-up including hemorheological measurements. 14 subjects quote the item: "I have the FHL". Although well matched with the 23 others for age and body composition, FHL subjects had higher plasma viscosity (1.44+/-0.05 vs 1.32+/-0.02 mPa.s; p<0.05) and a higher red cell aggregation as measured with laser backscattering (Affibio indices: final aggregation time "TF": 36.77+/-1.88 vs 44.26+/-2.37; p<0.05; aggregation index at 10 s "S10": 26.31+/-1.14 vs 21.92+/-1.19; p<0.05). The OTS score was correlated positively with plasma viscosity (r=0.549; p=0.008), whole blood viscosity (r=0.4458; p=0.03), and the following aggregability parameters: "S10" (r=0.4818; p=0.0232) and the aggregation index at 60 s "S60" (r=0.4601; p=0.0312). The OTS score was also correlated negatively with the aggregability parameters "TF" (r=-0.4432; p=0.0389) and the initial aggregation time "TA" (exponential relationship r=-0.458; p=0.03). These findings suggest that the feeling of heavy legs in overtrained athletes is related to OTS-related hemorheologic disturbances, namely mild plasma hyperviscosity and mild erythrocyte hyperaggregability.

Adult↗
PubMed2003

Hemorheological correlates of fitness and unfitness in athletes: moving beyond the apparent "paradox of hematocrit"?

UNLABELLED: Negative correlations between blood viscosity parameters and fitness have been reported, but their physiological meaning remains incompletely understood. Since rheo-active treatments are used in athletes doping, we aimed at clarifying the relationships between hematocrit (Hct), viscosity and performance by comparing aerobic capacity, overtraining questionnaire, and hemorheological parameters. SUBJECTS AND METHODS: 29 sportsmen (24.71+/-1.05 yr; 74.90+/-1.44 kg; 178.5+/-1.05 cm) underwent a standardised exercise test. Physical working capacity (W170), maximal power output (Wmax) and maximal oxygen consumption (VO2max ) were calculated. Viscometric measurements were done with a MT 90 Medicatest viscosimeter. Hct was measured with microcentrifuge. All subjects answered the overtraining questionnaire proposed by the French Society for Sports Medicine. RESULTS: The best correlate of maximal power output (Wmax) was whole blood viscosity (r=-0.383, p<0.001). The stepwise regression analysis only selected Hct as W170 determinant (r=-0.66, p<0.001). Similarly the best determinant of VO2max, expressed as a percentage of theoretical values, was Hct (r=-0.462, p=0.01). Hct/viscosity ratio (Hct/eta), a proposed index of Hct's positive influence on O2 transfer to tissues, was positively correlated to Wmax expressed as a percentage of theoretical values (r=0.487, p=0.02). The overtraining score was correlated to plasma viscosity (r=0.450, p=0.016). CONCLUSION: The best hemorheogical correlate of fitness is a low hematocrit and the best hemorheological correlate of overtraining is increased plasma viscosity.

Adult↗
PubMed2003

[Total osteotomy for maxillary setback. Indications, technique, results].

PURPOSE: Maxillary skeletal protrusion used to be treated by orthodontic treatment or combined surgical and orthodontic treatment consisting in extraction of two maxillary premolars associated with anterior maxillary osteotomy. Although the anterior occlusal result is quite often good, the esthetic impact is often unsatisfactory. Furthermore, these methods do not correct for the generally associated vertical maxillary excess nor for the first molar class II relation. MATERIAL AND METHODS: This retrospective study included 11 patients who underwent posterior repositioning of the maxilla between 1986 and 2001. The indication for surgery was based on clinical and cephalometric criteria as exposed. Patient evaluation was based on bony stability and relation between hard and soft tissue changes, and changes in hard and soft tissues cephalometric landmarks assessed prior to surgery, post operatively and six months post operatively. RESULTS: Results were considered quite good with restoration of a first molar Class I relation, restitution of facial harmony and an esthetic soft tissue profile. Cutaneous movements after surgery, the relation between hard and soft tissue changes and rate of relapse are reported. DISCUSSION: We compared our series with those reported in the literature emphasizing diagnostic and technical difficulties. This method, which provides good healing as well as the good stability can be recommended for surgical treatment of patients with maxillary protrusion associated with vertical maxillary excess.

Adolescent↗
PubMed2002

Simplified measurement of insulin sensitivity with the minimal model procedure in type 2 diabetic patients without measurement of insulinemia.

This study aimed to evaluate a simplified minimal model protocol for measuring insulin sensitivity in mild and severe type 2 diabetes, considering that changes in serum insulin during an insulin-modified intravenous glucose tolerance test almost only reflect the insulin injection. Two groups of diabetics treated with high doses of antidiabetic agents were recruited. Mean insulin responses were calculated in group 1 (n = 30). In group 2 (n = 38), we compared insulin sensitivity (SI) obtained with reference protocol with SI calculated by a minimal model procedure including the theoretical average insulin profile determined in group 1, and with Homeostasis Model Assessment (HOMA-R). Additionally, the cost of each procedure was calculated. SI measured by the reference method strongly correlated with SI determined by the simplified protocol (r = 0.966, p < 0.0001), while no correlation was found with HOMA-R (r = - 0.349, NS). Reduction of cost for HOMA-R and simplified minimal model procedure were - 92 and - 81 %, respectively. This simplified and relative inexpensive protocol, using minimal model procedure without insulin measurement, accurately measures SI regardless of beta-cell defect degree. This approach could be of interest when limits of validity of simple indexes are reached.

Costs and Cost Analysis↗
PubMed2002

Carbohydrate dependence during hard-intensity exercise in trained cyclists in the competitive season: importance of training status.

To test the hypothesis that intensive endurance training increases CHO utilisation during hard-intensity exercise, seven competitive road cyclists (Cy) performed three 50-min steady-state exercise tests on a cycle ergometer above their ventilatory threshold (+ 15 %) over the course of a cycling season (January [ET1], May [ET2] and September [ET3]). We compared the data with the baseline values of seven sedentary controls (Sed). CHO oxidation in Cy was higher in ET2 and ET3 than in ET1 (p < 0.05), was lower in ET3 than in ET2 (p < 0.05) and was higher in Cy than in Sed only in ET2 (p < 0.05). Lactate kinematics were lower in Cy than in Sed in all conditions (p < 0.05), but in Cy they were lower in ET2 than in ET1 and higher in ET3 than in ET2 (p < 0.05). Race performance was impaired and the overtraining score was increased at ET3 in comparison with ET2 (p < 0.05). We conclude that competitive cyclists increase CHO oxidation during hard-intensity exercise over the course of a season, but show a decline by the end of the season in association with the appearance of an overtraining state. Thus, well-trained cyclists develop a CHO dependence, which is modified with training status.

Adult↗
PubMed2002

Does growth hormone treatment alter skeletal muscle mitochondrial respiration in rats?

OBJECTIVE: Growth hormone (GH) has been shown to stimulate lipolysis and enhance lipid oxidation. We investigated whether GH could improve mitochondrial oxidative capacity. METHOD: Fourteen male Wistar rats received 14-day treatment with biosynthetic human GH (10 IU/kg/24 h) or placebo. Mitochondria were isolated from the total muscle of one hind limb of the rat. Mitochondrial oxygen consumption was measured in vitro using a Clark-type electrode with three substrates: palmitoyl-L-carnitine, pyruvate and succinate (+ rotenone). RESULTS: Muscle mitochondrial yield was not significantly different in the GH-treated group from that in controls. Neither the basal nor ADP-stimulated respiratory state reached a significant difference between the 2 groups with palmitoyl-L-carnitine, pyruvate, and succinate. CONCLUSION: GH treatment did not improve the oxidative capacity of skeletal muscle mitochondria.

Adenosine Diphosphate↗
PubMed2002

[Difficult surgical management of facial neurofibromatosis type I or von Recklinghausen disease in children].

We report a case of predominantly facial neurofibromatosis type I in a 7-year-old girl, exposing the difficulties encountered in surgical management. Infiltration of facial soft tissues by plexiform neurofibroma is difficult to control. Resection of large areas of facial skin is unconceivable, facial functions must be preserved. Orbitocranial surgery is reserved for orbital manifestations of neurofibromatosis with osseous sphenoid dysplasia and pulsatile exophthalmos. Despite progress in tumor imaging and surgery, facial neurofibromatosis remains a challenge for the surgeon. We discuss surgical technique and indications for surgery in these cases.

Child↗
PubMed2002

Regular exercise (3x45 min/wk) decreases plasma viscosity in sedentary obese, insulin resistant patients parallel to an improvement in fitness and a shift in substrate oxidation balance.

UNLABELLED: Exercise training decreases blood viscosity in athletes parallel with metabolic improvements mostly characterized by an increase in insulin sensitivity. Patients with low insulin sensitivity exhibit a host of metabolic disorders that may also benefit from regular training. However, the hemorheologic aspects of training in such subjects are not known and we aimed at characterizing them. SUBJECTS: Thirty-two obese insulin resistant subjects were tested before and after 2 months. Twenty-one of them were trained (3x45 min/wk) at a level defined by exercise calorimetry and corresponding to the power at which lipid oxidation reaches a maximum (LIPOX(max )) and eleven served as controls. The two groups were matched for age and body mass index. There was no weight change in controls while the 2 months training period decreased weight by 2.5 kg (p<0.02). This change was totally explained by a loss in fat mass (-2.7 kg, p<0.02) while fat free mass remained unchanged. Blood rheology was unchanged in the control group while training improved plasma viscosity eta(pl) (before: 1.43+/-0.03 mPa.s; after: 1.35+/-0.03 mPa.s, p<0.02). There was no change in either hematocrit, red cell rigidity or red cell aggregation. The balance of substrates oxidation shifted towards a higher use of lipids (point of crossover where subjects oxidize 70% carbohydrates 30% lipids: before 39.3+/-6.9 watts; after 70.8+/-6 watts, p<0.001; point where lipid oxidation is maximal (LIPOX(max )) before: 16.5+/-1.4 watts; after: 21.4+/-1.3 watts, p<0.001) and V(O(2max )) increased by 74% (p<0.01). Consistent with observations in athletes, the metabolic and ergometric improvements induced by training reduces eta(pl) in sedentary, insulin resistant patients, but at those low levels training does not appear to induce "autohemodilution" (as reflected by hematocrit) neither it improves red cell deformability or aggregation. The reliability of eta(pl) as simple and unexpensive marker of efficiency of training in insulin resistant patients should be further evaluated.

Blood Physiological Phenomena↗
PubMed2002

Postexercise red cell aggregation is negatively correlated with blood lactate rate of disappearance.

In three separate studies, we have observed that the rise in blood lactate during exercise is correlated to blood viscosity and red cell aggregation. Whether these results were related to an effect of blood rheology on lactate production by muscles or on lactate disappearance remains unknown. The modelling of postexercise lactate kinetics allows a fair evaluation of lactate production by muscles (gamma1) and lactate disappearance (gamma2), the latter being easily measurable with simplified protocols. We thus investigated the relationships between pre- and postexercise blood rheology and gamma2. Ten subjects (2 female and 8 males; age 16-45 yr, weight 62-106.5 kg) exhibiting a wide range of gamma2 (from 2 to 7.7x10(-2) min(-1)) underwent a maximal exercise-test with postexercise calculation of gamma2 with the simplified formula gamma2=0.0724+0.755(Lac8-Lac20)/(Lac8.Deltat)-0.00684Lac20 where Lac8 and Lac20 are lactate concentrations 8 and 10 min after exercise stop at the level of VO2max, as previously reported. During exercise whole blood viscosity eta(b) increased (+15%, p<0.01) due to a rise in hematocrit (p<0.05) and plasma viscosity (+0.08+/-0.03 mPa.s, p<0.05), while red cell rigidity was unchanged. Red cell aggregation (Myrenne M1) increased by 11% (p<0.05). Postexercise M1 (measured at VO2max) was the only hemorheologic parameter correlated to gamma2 (r=-0.697, p=0.037). We find once again a statistical relationship between lactate at exercise and red cell aggregation. Microcirculatory adaptations influenced by red cell aggregation may influence lactate disposal (as reflected by gamma2), adding its effect to that of the balance between carbohydrates and fat oxidation which is the major determinant of blood lactate concentrations at exercise in physiological conditions.

Adult↗
PubMed2002

[Tongue metastasis from esophageal adenocarcinoma. A case report].

Metastasis within the buccal cavity is a relatively uncommon finding observed in about 1% of malignant tumors in this region. Mandibular or maxillary bones are usually involved as well as soft tissues. Tongue involvement is rare. Secondary localizations arising from the esophagus are exceptional. These metastatic disseminations occur at advances stages. We report a case of tongue metastasis from an esophageal adenocarcinoma in a 73-year-old man who had undergone surgery for lower esophageal adenocarcinoma a few months earlier. The clinical presentation in this context was suggestive of a metastatic process confirmed at histology. Careful pathology examination is required to distinguish primary from secondary localizations and establish the diagnosis of metastasis.

Adenocarcinoma↗
PubMed2002

Reduction of fat accumulation and lipid disorders by individualized light aerobic training in human immunodeficiency virus infected patients with lipodystrophy and/or dyslipidemia.

BACKGROUND: The management of abdominal fat accumulation and metabolic disorders in HIV1-infected patients, by an aerobic training program, is considered. METHODS: Seventeen lipodystrophic and 2 dyslipidemic (without body modification) adults were studied before and after 4 months of training. The training load was individualized on a ventilatory threshold basis, determined during a maximal exercise test on cycle ergometer. Total (TAT), Visceral (VAT) and Subcutaneous Adipose Tissue (SAT) were assessed by CT-scan. Total (TC) and High Density Lipoprotein (HDL-C) Cholesterol, Triglycerides (TG), lactate (La), insulin and glucose were measured after a 12-hour-overnight fast. LDL, TC/HDL, TG/HDL, HOMA-insulin resistance index and coronary heart disease (CHD) relative risk (RR(CHD)) were calculated. RESULTS: Besides a significant improvement of aerobic fitness, trained patients exhibited a reduction in TAT (-12.8%, p < 0.001), specially at the visceral level (- 12%, p < 0.01) and in TC, TG and La (- 23%, - 43% and - 19% respectively, p < 0.01). HDL-C was increased (+ 6%, p < 0.01). All these effects were above changes that could be expected by a possible regression to the mean artefact. Both TC/HDL and TG/HDL were reduced (p < 0.01) and the estimated RR(CHD) decreased by approximately 13% (p < 0.01). No significant training effect was observed on the 9 available HOMAs. Significant correlations were found between changes in blood lipid values and baseline measures (r range - 0.55 to - 0.79, p < 0.05), indicating a larger improvement when baseline lipid parameters were higher. CONCLUSION: Aerobic training reduced visceral fat, lipid disorders, basal blood lactate and CHD markers in HIV patients. Training effects were particularly important for patients with marked dyslipidemia.

Adipose Tissue↗
PubMed2001

Venous blood lactate increase after vertical jumping in volleyball athletes.

The aim of this study was to test the hypothesis that venous blood lactate concentrations ([La-]) would vary from the beginning of brief exercise. Maximal vertical jumping was used as a model of brief intense exercise. Eleven healthy male volleyball players, aged [mean (SE)] 18.5 (0.7) years, performed three exercise tests with different protocols, each separated by quiet seated recovery periods of 45 min. After the first test, consisting of a single maximal jump [lasting approximately equals 0.6 s for the pushing phase, and in which the subjects jumped 64 (2.2) cm], forearm venous [La-] increased significantly with respect to rest at 1 min (t1), 3 min (t3), and 5 min (t5) of recovery. The second test, comprising six maximal jumps, each separated by 20-s recovery periods, resulted in an unchanged [La-] with respect to the baseline value. After the third test [i.e., six consecutive maximal jumps that lasted a total of 7.36 (0.33) s], [La-] increased significantly at t3 and t5 with respect to the pre-test value (F= 10.3, P < 0.001). We conclude that a significant venous [La-] increase occurs after vertical jumping. This result may be explained by the activation of lactic anaerobic metabolism at the very onset of exercise, which participates in energy production and/or in the resynthesis of the phosphocreatine that was used during such brief exercise.

Adolescent↗
PubMed2001

Non-Hodgkin's lymphoma of the testis: a retrospective study of 84 patients treated in the French anticancer centres.

Primary non-Hodgkin's lymphoma of the testicle is rare. We analysed cases treated in French anticancer centres from 1969 to 1995. All cases were reviewed and classified according to the R.E.A.L. Classification. Eighty-four cases were included in this study. The median age was 67 years (17-85). Disease was classified as stages I in 42 cases, stages II in 19 and stages III-IV in 23. Diffuse large B-cell lymphoma was diagnosed in 75% of cases. Treatment included orchidectomy and radiotherapy and/or chemotherapy. A complete response was obtained in 72.6% of the patient population and in 100%, 68% and 33% of stage I, II and III-IV disease respectively. Recurrence occurred in 32 cases and the most frequent site was the central nervous system: six of these patients presented stage I disease. Median overall survival was 32 months for the entire population, 52 months for stage I, 32 months for stage II, and 12 months for stage III-IV cases (P < 0.0001). Among patients presenting stage I disease, no difference was found between those treated with combined surgery and chemotherapy or surgery followed or not followed by radiotherapy. This study confirms that non-Hodgkin's lymphoma of the testicle carries a poor prognosis. Systemic adjuvant chemotherapy should be discussed because of the high recurrence rate. Inclusion of these cases in large co-operative prospective studies is recommended.

Adolescent↗