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Biomedical subjects

J Mercier

Publications and source records attributed to J Mercier.

At least 127 records · Page 7Linked to original sources
PubMed1996

Lactate kinetics during passive and partially active recovery in endurance and sprint athletes.

We investigated the effects of passive and partially active recovery on lactate removal after exhausting cycle ergometer exercise in endurance and sprint athletes. A group of 14 men, 7 endurance-trained (ET) and 7 sprint-trained (ST), performed two maximal incremental exercise tests followed by either passive recovery (20 min seated on cycle ergometer followed by 40 min more of seated rest) or partially active recovery [20 min of pedalling at 40% maximal oxygen uptake (VO2max) followed by 40 min of seated rest]. Venous blood samples were drawn at 5 min and 1 min prior to exercise, at the end of exercise, and during recovery at 1, 2, 3, 4, 5, 6, 8, 10, 15, 20, 30, 40, 50, 60 min post-exercise. The time course of changes in lactate concentration during the recovery phases were fitted by a bi-exponential time function to assess the velocity constant of the slowly decreasing component (tau 2) expressing the rate of blood lactate removal. The results showed that at the end of maximal exercise and during the 1st min of recovery, ET showed higher blood lactate concentrations than ST. Furthermore, ET reached significantly higher maximal exercise intensities [5.1 (SEM 0.5) W.kg-1 vs 4.0 (SEM 0.3) W.kg-1, P < 0.05] and VO2max [68.4 (SEM 1.1) ml.kg-1.min-1 vs 55.5 (SEM 5.1) ml.kg-1.min-1, P < 0.01]. There was no significant difference between the two groups during passive recovery for tau 2. During partially active recovery, tau 2 was higher than during passive recovery for both groups (P < 0.001), but ET recovered faster and sooner than ST (P < 0.05). Compared to passive recovery, the tau 2 measured during partially active recovery was increased threefold in ET and only 1.5-fold in ST. We concluded that partially active recovery potentiates the enhanced ability to remove blood lactate induced by endurance training.

Adult↗
PubMed1996

Lactate uptake by forearm skeletal muscles during repeated periods of short-term intense leg exercise in humans.

We investigated the role of the forearm skeletal muscles in the removal of lactate during repeated periods of short-term intensive leg exercise, i.e. a force-velocity (FV) test known to induce a marked accumulation of lactate in the blood. The leg FV test was performed by seven untrained male subjects. Arterial and venous blood samples for determination of arterial ([la-]a) and venous ([la-]v) plasma lactate concentrations were concomitantly taken at rest before the test, during the FV test at the end of each period of intensive exercise just before the 5-min between-sprint recovery period, and after the completion of the test at 2, 4, 6, 8, 10, 15, and 20 min of the final recovery. The arteriovenous difference in concentration for plasma lactate ([la-]a-v) was determined for each blood sample. During the test, [la-]a and [la-]v increased significantly (P < 0.001; P < 0.001) with significantly higher values for [la-]a (P < 0.001). At the onset of the test, [la-]a-v became positive and increased up to a braking force of 6 kg, correlating significantly with [la-]a (r = 0.61, P < 0.001) with power (r = 0.58, P < 0.001) during the test. At the end of the test, [la-]a, [la-]v and [la-]a-v decreased (P < 0.001; P < 0.001; P < 0.001 respectively) but were still higher than the basal values after 20-min of passive recovery. In conclusion, forearm skeletal muscles would seem to have been involved in the removal of lactate from the blood during the leg FV test, with an increase in lactate uptake proportional to the increase in plasma lactate concentration and power.

Adult↗
PubMed1996

Exercise tolerance in patients with mitral stenosis before and after acute percutaneous mitral valvuloplasty. Role of lung diffusing capacity limitation?

The aim of this study was to specify in patients with tight mitral stenosis whether lung diffusing capacity could play a role in their exercise intolerance. A similar study was recently carried out in patients with moderate chronic heart failure. Ten patients with tight mitral stenosis were studied before and 6 months after successful percutaneous transvenous balloon valvuloplasty and compared to six control subjects. Measurements of diffusing capacity, evaluated by the lung transfer factor (TLCO) and by the transfer coefficient (TLCO/VA), obtained at rest and during early recovery after cardiopulmonary exercise testing were performed. Cardiac output was determined non-invasively, both at rest and during exercise, using the carbon dioxide exponential rebreathing technique. Prior to valvuloplasty, TLCO and TLCO/VA were not different at rest between the two groups. During exercise, patients differed from control subjects, with lower oxygen uptake (P < 0.001) and lower cardiac output at peak exercise (P < 0.001). These values at peak exercise were significantly correlated (P = 0.02; r = 0.75). Moreover, patients differed from control subjects at early recovery after peak exercise with an absence of increase in TLCO (P < 0.05). Six months after valvuloplasty, a decrease of both TLCO (P < 0.01) and TLCO/VA (P < 0.05) was observed at rest. During exercise, comparison of patients demonstrated a significant increase of both peak exercise oxygen uptake (SLVO2, P < 0.01) and cardiac output (P < 0.001). At early recovery after peak exercise there was a significant increase in TLCO (P < 0.05) and TLCO/VA (P < 0.01), such that a delta TLCO and a delta TLCO/VA appeared (P < 0.05) identical to that observed in control subjects. Moreover, delta SLVO2 was significantly correlated in patients with delta Q+ delta TLCO/VA (P = 0.02; r = 0.72). In conclusion, this study suggests a role, at least partial, of lung diffusing capacity in exercise intolerance in patients with tight mitral stenosis and in the improvement of their aerobic exercise capacity demonstrated after successful percutaneous balloon valvuloplasty.

Adult↗
PubMed1996

Influence of post-surgery time after cardiac transplantation on exercise responses.

Influence of post-surgery time after cardiac transplantation on exercise responses. Med. Sci. Sports Exerc., Vol. 28, No. 2, pp. 171-175, 1996. To test the hypothesis that exercise response changes with time after cardiac transplantation, we investigated the cardiorespiratory responses of nine orthotopic heart transplant patients (52.4 +/- 2 yr) during graded exercise tests (30 W.3 min-1) done at 1, 3, 6, 9 and 12 months post-surgery. At peak exercise, 1) oxygen uptake per kg of body weight (VO2), minute ventilation (VE) and oxygen pulse (O2 pulse) did not change significantly between 1 and 12 months postsurgery; 2) transplanted heart rate (HRt) and delta heart rate (peak exercise heart rate--resting heart rate) increased significantly over time (P < 0.01; P < 0.05) with a marked increase between 1 and 3 months (P < 0.05); and (3) a significant negative correlation existed between O2 pulse and HRt (r = -0.36, P < 0.05), whereas no correlation was found between delta heart rate and delta VO2 (peak exercise VO2- resting VO2, l.min-1). During submaximal exercise, HRt increased significantly over time (P < 0.001); VO2, VE, and O2 pulse showed no significant change; and the VO2-HRt relationship shifted toward higher values of HRt. We conclude that, in the absence of formal physical training, the exercise response of denervated transplanted heart increases in relation to post-surgery time but does not affect oxygen uptake at submaximal and peak levels of exercise.

Blood Pressure↗
PubMed1996

Effects of active recovery on plasma lactate and anaerobic power following repeated intensive exercise.

The purpose of this study was to investigate the effects of active recovery (AR) on plasma lactate concentration [La] and anaerobic power output as measured during repeated bouts of intense exercise (6 s) against increasing braking forces. Ten male subjects performed two randomly assigned exercise trials: one with a 5-min passive recovery (PR) after each exercise bout and one with a 5-min active recovery (AR) at a workload corresponding to 32% of maximal aerobic power. Blood samples were taken at rest, at the end of each exercise bout (S1) and at the 5th minute between bout-recovery (S2) for plasma lactate assay. During the tests, [La]S1 was not significantly different after AR and PR, but [La]S2 was significantly lower after AR for power outputs obtained at braking forces 6 kg (5.66 +/- 0.38 vs 7.56 +/- 0.51 mmol.l-1) and peak anaerobic power (PAnP) (6.73 +/- 0.61 vs 8.54 +/- 0.89 mmol.l-1). Power outputs obtained at 2 and 4 kg did not differ after AR and PR. However, when compared with PR, AR induced a significant increase in both power outputs at 6 kg (842 +/- 35 vs 798 +/- 33 W) and PAnP (945 +/- 56 vs 883 +/- 58 W). These results showed that AR between bouts of intensive exercise decreased blood lactate concentration at high braking forces. This decrease was accompanied by higher anaerobic power outputs at these forces.

Adult↗
PubMed1996

Exercise-induced death in sickle cell trait: role of aging, training, and deconditioning.

The pathophysiological process of exercise-induced death in subjects with sickle cell trait (SCT) remains unclear. Concerning the cause of death, authors have suggested stressful environmental conditions such as altitude, heat and humidity, or abnormal patient conditions such as deconditioning, fatigue, and disease. These conditions are thought to lead to hypoxemia, hyperlactatemia, acidosis, dehydration, hyperthermia, or exercise-induced rhabdomyolysis, all of which may initiate sickle cell crisis, disseminated intravascular coagulation, myoglobinuria, and renal failure. We report the case of a 41-yr-old, healthy, and apparently well-conditioned subject with SCT who died during a cross-country race under normal environmental conditions in good weather (in terms of temperature and humidity). The medical and athletic history of the subject were unremarkable. We refer to an epidemiological study that reported a relation between age and exercise-induced sudden death in subjects with SCT. We then review the pathophysiological effects of aging in association with deconditioning and high-level training reported in the literature, particularly the decrease in aerobic metabolism in deconditioned subjects, and the exercise-induced hypoxemia in highly trained subjects. We discuss the consequences of deconditioning and high-level training in subjects with SCT during exercise, and conclude that these factors may be involved in the age-dependent risk of exercise-related sudden death in subjects with SCT.

Adult↗
PubMed1996

Lactate uptake by skeletal muscle sarcolemmal vesicles decreases after 4 wk of hindlimb unweighting in rats.

We investigated the effects of 4 wk of hypodynamia on the rate of lactate transport in skeletal muscle sarcolemmal vesicles from control and hindlimb-suspended rats. Characterization of the sarcolemmal preparations was achieved with a marker enzyme (K+-p-nitrophenylphosphatase) and measurement of 1 mM [U-14C]lactate transport activity under zero-trans conditions with or without a pH gradient or the transport inhibitor alpha-hydroxycinnamate. Preparations from the two groups were not significantly different concerning yield and purification. Based on these results, we used this model to analyze the lactate transport activity after hypodynamia by tail suspension. Hindlimb suspension caused a shift from slow to fast myosin heavy chain isoforms in soleus muscles with a 40% decrease in the citrate synthase activity (from 35.3 +/- 3.7 to 21.4 +/- 2.1 mu mol x g-1 x min-1; P < 0.05). Lactate (1 mM) uptake in vesicles from the two groups was a function of time, and the rate after hindlimb suspension was significantly decreased in the suspended compared with the control group (2.25 +/- 0.44 and 3.50 +/- 0.26 nmol x min-1 x mg protein-1, respectively; P < 0.05). These differences were not observed for a higher lactate concentration (50 mM). These results suggest that the level of physical activity plays a role in the regulation of sarcolemmal lactate transport activity implicated in the exchanges of lactate between producing and utilizing cells, organs, and tissues, which are major ways of carbohydrate energy distribution in humans and others species.

4-Nitrophenylphosphatase↗
PubMed1996

Effect of 2-chloropropionate on initial lactate uptake by rat skeletal muscle sarcolemmal vesicles.

2-Chloropropionate (2-CP) is a halogenated monocarboxylic acid generally used to decrease blood lactate concentration in various metabolic states. To investigate whether it has an inhibitory effect on sarcolemmal lactate transport, we compared the initial rate of lactate transport in sarcolemmal membrane vesicles purified from 20 male Wistar rats with and without 2-CP. Transport by these vesicles was measured as uptake of L-(+)-[U-14C]lactate under pH gradient-stimulated cis inhibition. The time courses of 1 mM L-(+)-lactate uptake into vesicles both with and without 10 mM 2-CP (L- or D-) displayed saturation kinetics. Lactate uptake values were lower with 10 mM L-2-CP and 10 mM D-2-CP in comparison to the control values. Both 10 mM L-2-CP and 10 mM D-2-CP significantly inhibited 1 mM L-(+)-lactate uptake (55.8 +/- 9.1 and 53.5 +/- 12.1%, respectively; P < 0.001), whereas a smaller inhibition was observed with a higher lactate concentration of 50 mM (40.2 +/- 11.2 and 38.7 +/- 12.4%; P < 0.001 and P < 0.05, respectively). However, a higher D-2-CP concentration (50 mM) increased the inhibition of pH-stimulated 1 mM L-(+)-lactate uptake (77.0 +/- 9.4%; P < 0.001). D-2-CP had a trans-stimulation effect on the initial rate of lactate efflux of 1 mM L-(+)-lactate compared with baseline efflux (9.5 +/- 0.8 vs. 5.1 +/- 0.4 nmol.min-1.mg protein-1; P < 0.05). 2-CP significantly inhibited the initial rate of lactate uptake in skeletal muscle sarcolemmal membrane vesicles. This result suggests that 2-CP is a nonstereoselective substrate of the lactate muscle carrier that impairs lactate transport.

Animals↗
PubMed1996

[Impact of antimitotic chemotherapy on the dentition. Apropos of 71 cases].

The authors show the responsibility of antimitotic chemotherapy on the disturbances in dental development in the young children. They insist on doing an odonto-stomatologic check-up at the beginning of the treatment and to keep a constant watch during the treatment and until the end of dental evolution.

Adolescent↗
PubMed1996

[The coral orbital floor. Its value in traumatology. The results of a multicenter study of 83 cases].

A madreporic coral graft was used for orbital floor reconstruction following facial trauma. This report presents a multicentric study of 83 patients with a follow-up period of 15 to 24 months. The results of this study indicate no significant rejection or infection opposed to so many synthetic implants outcome. The radiological follow-up demonstrates a partially resorption of the implant within about 2 years and its replacements by new bone. Coral implant was used to correct enophthalmos or diplopia due to enlarged orbital dimensions. It was technically easy to insert and its anatomic shape does not require to be fashioned before use. Its inflexibility allows to bridge large bone defects and this implant should be considered as an attractive alternative to autogenous grafts, avoiding a second surgical site, in reconstructing orbital floor fractures.

Adolescent↗
PubMed1996

[Trismus disclosing Horton's disease].

The authors report a giant cell arteritis case associating trismus and hemifacial oedema in a febrile context. After spontaneous regression of other manifestations, the apparition of more typical signs allowed to associate the diagnosis of temporal arteritis, later confirmed histologically. Thus, when facing a trismus case, even more when fever is present, it seems important to associate with the Horton's disease, no matter what the antecedents found at the interrogatory be, whether initial or isolated. The Doppler reveals flux abnormalities of the superficial branches of the external carotid. The examination of facial, temporal and internal maxillary arteries has a good negative predictive value in this pathology. It would be useful in therapeutic supervision.

Biopsy↗
PubMed1996

[5 conventional radiographic projections are necessary and sufficient for the study of the zygoma. Technics and results].

Though clinic examination gives us much information, radiology still is essential in head trauma. Many standard radiographic projections have been described in the past and yet since the eighties it appears that C.T. scanner (C.T.) has become absolutely necessary to a great number of us. In fact, C.T. is indispensable when there is a matter of vital urgency or when a functional problem appears (diplopia). But most of the time high quality standard radiographic projections are sufficient. We have selected five radiographic projections: the occipito-mental's such as Mahoney's or Blondeau or Louisette, the submento-vertical's, the rotated occipito-mental's. For each of these radiographic projections we have specified the angular definition, the realization techniques, the criterions of quality and the results. The use of conventional radiology gives us images of which the quality is high enough to allow a precise topographical diagnosis and is far cheaper than C.T. So we can assert that standard radiographic projections are necessary and sufficient and that the use of C.T. becomes indispensable only in the few cases of diplopia or enophthalmia or complicated maxillary fracture. In the case of a lateral head trauma, our strategy of radiographic exploration will be represented as indicated on picture n degrees 20.

Craniocerebral Trauma↗
PubMed1995

Aerobic and anaerobic contribution to Wingate test performance in sprint and middle-distance runners.

We investigated the aerobic and anaerobic contributions to performance during the Wingate test in sprint and middle-distance runners and whether they were related to the peak aerobic and anaerobic performances determined by two commonly used tests: the force-velocity test and an incremental aerobic exercise test. A group of 14 male competitive runners participated: 7 sprinters, aged 20.7 (SEM 1.3) years, competing in 50, 100 and 200-m events and 7 middle-distance runners, aged 20.0 (SEM 1.0) years, competing in 800, 1,000 and 1,500 m-events. The oxygen uptake (VO2) was recorded breath-by-breath during the test (30 s) and during the first 20 s of recovery. Blood samples for venous plasma lactate concentrations were drawn at rest before the start of the test and during the 20-min recovery period. During the Wingate test mean power (W) was determined and three values of mechanical efficiency, one individual and two arbitrary, 16% and 25%, were used to calculate the contributions of work by aerobic (Waer,ind,16%,25%) and anaerobic (Wan,ind,16%,25%) processes. Peak anaerobic power (Wan,peak) was estimated by the force-velocity test and maximal aerobic energy expenditure (Waer,peak) was determined during an incremental aerobic exercise test. During the Wingate test, the middle-distance runners had a significantly greater VO2 than the sprinters (P < 0.001), who had significantly greater venous plasma lactate concentrations (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Exercise intolerance in patients with chronic heart failure: role of pulmonary diffusing limitation.

In order to test the hypothesis of pulmonary diffusing capacity involvement in exercise limitation in subjects with chronic heart failure (CHF), lung transfer factor (TLCO), oxygen saturation (SaO2), cardiac output (CO) and gas exchange were studied over the course of an incremental exercise test in 10 patients and 10 controls. The TLCO and transfer coefficient for carbon monoxide (TLCO/VA) were measured at rest and during recovery by the single breath method. The SaO2 was followed non-invasively with a finger oximeter and CO was determined according to the carbon dioxide rebreathing method. Analysis of respiratory variables at maximal effort showed significantly lower values in patients with CHF as regards peak oxygen uptake (VO2), minute ventilation (VE), heart rate (HR), oxygen pulse (O2 pulse), and CO with higher ventilatory reserve (VR) than controls. At a comparable workload (30 W), patients with CHF demonstrated higher values for VE and lower values for CO than controls. The TLCO, expressed as percent of predicted values, was significantly lower in CHF patients than controls, respectively, at rest (90.5 +/- 3.75% vs 106.8 +/- 3.8%) and within 5 min after maximal exercise (87 +/- 4.4% vs 117.4 +/- 3.81%). The TLCO/VA showed comparable data between the two groups at rest (81.7 +/- 3.28 vs 90.3 +/- 2.86%). However, significantly lower values of TLCO/VA were obtained for CHF after maximal exercise in comparison to control subjects (77.5 +/- 3.85% vs 96.3 +/- 3.95%). These results confirm the alteration of the main variables in relation to cardiopulmonary exercise limitation in-tHF, and indicate a significant decrease in TLCO and TLCO/VA after maximal exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise↗
PubMed1995

[Standard radiography of the mandibular condyle in the dental office. The modified Parma and the Zimmer trans-orbital production technic using a retro-alveolar radiologic unit].

Trauma to the condylar area is rather frequent and the stomatologist should be capable of performing a standard radiographic exploration. Two incidences performed in the stomatologist's office using a dental tube appear to be essential. The modified Parma and the transorbitary Zimmer incidences are needed for lateral and anteroposterior views respectively. The equipment required for these views are described together with several examples.

Female↗
PubMed1995

[Orthognathic surgery with missing teeth].

Orthognathic surgery in patients with missing teeth can be divided into two categories. In the first case after tooth loss, specially designed bridging is required using the prosthesis already in place. In the second case in patients with congenital deficiencies, usually sequellae of cleft palate, there is a wider range of therapeutic options which are discussed on the basis of observed cases.

Anodontia↗
PubMed1995

[Maxillofacial manifestations of Steinert's myotonic dystrophy. Clinical and therapeutic aspects].

The craniofacial manifestations, together with teleradiographic and cephalometric findings, of Steinert's dystrophy were examined based on a review of the literature and the clinical features of several patients with myotonic dystrophy leading to the diagnosis of Steinert's disease. The prevalence of the functional impairments due to facial deformation varies with the severity of the disease, suggesting early interceptive treatment supported by orthopaedic care and rehabilitation therapy of orofacial functions. Surgery involves bimaxillary osteotomy which can improve mastication and facial morphology. Operative risks should be carefully identified with adequate explorations before surgery.

Adolescent↗