Biomedical subjects

F Carré

Publications and source records attributed to F Carré.

At least 19 recordsLinked to original sources

PubMed2006

Alterations of beta3-adrenoceptors expression and their myocardial functional effects in physiological model of chronic exercise-induced cardiac hypertrophy.

Physical training induces cardiovascular autonomic nervous system regulation adaptations, which could result from beta adrenergic receptor (AR) modifications. Among them, beta(3 )AR alterations have been recently reported but their functional effect remained to discuss. To explain the beta(3) AR gene expression in relation to function, we simultaneously studied the left ventricle (LV) beta(3) AR mRNA and protein levels and the myocardial functional effects of a beta(3) AR agonist following physical training. Forty rats were assigned to either a control (C; N = 20) or a trained (T; N = 20) group. The treadmill running protocol was performed for 8 weeks. Histological measurements on LV slices were quantified. The beta(3) AR mRNA abundance was studied with RT-PCR and beta(3) AR protein density with Western-Blot analysis. Myocardial functional effects of a beta(3) AR agonist, BRL37344 (10(-8) M), were studied in Langendorff-perfused hearts. Histological data confirmed the adapted patterns of the physiological cardiac hypertrophy observed in T (P < 0.01), with a significant increase in arteries density (P < 0.01) and an unchanged collagen concentration. The beta(3) AR protein density was increased in T (154 +/- 38% in T vs. 100 +/- 24% in C; P < 0.05), but no change was noted concerning the beta(3) AR mRNA level. After BRL37344 perfusion LVDP, +dP/dT and -dP/dT, in C (P < 0.01), and only +dP/dT in T (P < 0.05) were decreased. Moreover, all LV hemodynamic parameters were more altered after BRL37344 in C than in T (P < 0.01).Thus, in this physiological model of cardiac hypertrophy, an increase of beta(3) AR density without beta(3) AR mRNA alteration was observed. Classical negative myocardial lusitropic and inotropic effects induced by a specific agonist of beta(3) AR were diminished in trained rats.

Animals↗

PubMed2006

[What is the athlete's heart?].

The different components of the cardiovascular system adapt to the stress related to physical training. These adaptations, mainly functional and partly morphological, concern both the heart and the vessels. They play a key role in physical performance improvement, especially in case of endurance sports.

Adaptation, Physiological↗

PubMed2006

[Sports activity in heart disease: synthesis of new recommendations].

The practice of moderate and regular sports is beneficial for health, and should then always be promoted. The intensive practice of sports, especially for competition, increases the risk of cardiovascular events in patients with heart disease. Facing to a patient with heart disease requiring a certificate of non-contra-indication for sports practice, the cardiologist can sometimes consider himself/herself helpless for managing accurately the situation. Recently, recommendations have been published and summarized herein, in order to guide the final decision.

Cardiovascular Diseases↗

PubMed2005

Effect of remifentanil with and without atropine on heart rate variability and RR interval in children.

Remifentanil can cause bradycardia either by parasympathetic activation or by other negative chronotropic effects. The high frequency (HF) component of heart rate variability (HRV) is a marker of parasympathetic activity. This study aimed to evaluate the effect of remifentanil on RR interval and on HRV in children. Forty children ASA I or II were studied after approval by the human studies committee and informed parental consent was obtained. After stabilisation at sevoflurane 1 MAC, they were randomly divided into two groups: one received a 20 microg.kg(-1) atropine injection (AT + REMI) and the other ringer lactate solution (REMI). Three minutes later, a 1 microg.kg(-1) bolus of remifentanil was administered over 1 min, followed by a continual infusion at 0.25 microg.kg(-1).min(-1) for 10 min increased to 0.5 microg.kg(-1).min(-1) for a further 10 min. A time varying, autoregressive analysis of RR sequences was used to estimate classical spectral parameters: low (0.04-0.15 Hz; LF) and high (0.15-0.45 Hz; HF) frequency, whereas the root mean square of successive differences of RR intervals (rmssd) was derived directly from the temporal sequence. Statistical analyses were conducted by means of the multiple correspondence analysis and with non parametrical tests. Remifentanil induced an RR interval lengthening, i.e. bradycardia, in both groups compared to pretreatment values and was associated with an increase of HF and rmssd only for the REMI group. The parasympathetic inhibition by atropine did not totally prevent remifentanil's negative chronotropic effect. A direct negative chronotropic effect of remifentanil is proposed.

Adolescent↗

PubMed2005

[Use of the six-minute walk test in cardiology].

The symptom-limited exercise test is nowadays the gold standard to assess the exercise tolerance and the effects of different treatments in patients with chronic heart failure (CHF). A simpler alternative to this test is the 6-minute walk test. The 6-minute walk test is easy to realize and well-tolerated. Moreover, it is reliable just after one familiarization practice and requires standardization. Indeed, its conduction, which is submitted to some security precautions, can be altered by variation factors. The distance walked during the 6 minutes was the only parameter studied during the test. This parameter could allow judging the CHF severity and prognostic. The analyse of cardiorespiratory parameters has shown that the 6-minute walk test relative intensity is near to the peak individual values. Moreover, the cardiac and ventilatory adaptation of patient during this test depends to his own functional capacity. Lastly, the 6-minute walk test is a submaximal constant-load exercise, which should be performed in complement to the symptom-limited exercise test in cardiac patients.

Exercise Test↗

PubMed2003

[Genetic aspects of the athlete's heart].

Positive myocardial and vascular adaptations can be observed in case of a high physical training practice. These clinical, electrocardiographic and echocardiographic patterns constitute the so called "athlete's heart". These adaptations are linked to hemodynamic and neuro-hormonal factors but also for a large part to genetic factors. The "athlete's heart" genetics aspects are many. These genetic factors play a role not only for the absolute physical performance but also for the cardio-vascular responses to physical training. In other words, it is possible to separate the "high-responders" and the "low-responders" to physical training. A high number of genes seem involved in physical performance and in cardiovascular responses. Among them the renin-angiotensin system genes have been presently the most studied, because of their link with cardiac hypertrophy. The impact of the genes involved in the autonomic nervous system regulation begins also to be explored. In the future, several other genetic ways would be studied to really understand all the genetic aspects of the "athlete's heart".

Adaptation, Physiological↗

PubMed2002

[Cardiovascular benefits and hazard of physical practice].

The benefits of regular physical activity have been demonstrated in numerous epidemiologic studies in primary and secondary prevention of coronary artery disease. However, even high level physical activity is not an absolute guarantee against complications of coronary artery disease. Sudden death remains a major complication of sports. Beyond 35-40 years of age, coronary artery disease is the main cause of sudden death during physical activity. In normotensive as well as hypertensive subjects, physical activity lowers blood pressure. It also has beneficial effects on body fat and increases HDL-cholesterol. Likewise, physical activity has documented beneficial effects in diabetic patients, for type 1 as well as type 2 diabetes mellitus. Overall, the advantages of regular physical activity clearly exceed the potential risk of sudden death which is usually caused by heavy exertion in otherwise unaware coronary patients.

Autonomic Nervous System↗

PubMed2002

Effect of endurance training on oestrogen receptor alpha transcripts in rat skeletal muscle.

Endurance training induces, in female rats, alterations of oestrous cycle with decrease in plasma oestradiol levels. Moreover, it is well known that oestradiol concentrations modify oestrogen receptor levels. In order to further explain the effects of oestrogens on skeletal muscles, we hypothesized that endurance training modifies the levels of oestrogen receptor alpha messenger ribonucleic acid (ER alpha mRNA) in rat gastrocnemius muscle. Wistar rats were separated into four groups: male controls (C(m)) (n=7), female controls (C(f)) (n=6), male trained (E(m)) (n=7) and female trained (E(f)) (n=6). The endurance training programme was performed for 7 weeks, 5 days week-1 and consisted of 1 h of continuous running on an adapted motor-driven treadmill. At the end of the training session, the gastrocnemius muscle was isolated, weighed and semiquantification of ER alpha mRNA was performed using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. The citrate synthase (CS) activity of the gastrocnemius muscle was measured by a fluorimetric method. The CS activity of the male and female gastrocnemius muscle, respectively, 100 +/- 7% in C(m) (n=7) vs. 120 +/- 14% in E(m) (n=6, P < 0.01) and 100 +/- 13% in C(f) (n=6) vs. 138 +/- 23% in E(f) (n=6, P < 0.01) was significantly increased after 7 weeks of training. The ER alpha mRNA levels were significantly increased in E(f) compared with C(f) (0.49 +/- 0.15 vs. 0.31 +/- 0.11, P < 0.01) but not in E(m) compared with C(m) (0.37 +/- 0.15 vs. 0.37 +/- 0.13). In conclusion, these results demonstrate that 7 weeks of endurance training increased the level of transcripts encoding ER alpha in rats with the increase restricted to the females.

Amino Acid Sequence↗

PubMed2002

Effect of endurance training on oestrogen receptor alpha expression in different rat skeletal muscle type.

It is well known that oestrogens exert muscle anabolic and metabolic effects. Oestrogens act via specific oestrogen receptor (ER) proteins. The mainly represented oestrogen receptor alpha messenger ribonucleic acid subtype (ER(alpha) mRNA) was described in various tissues including the skeletal muscle. Moreover, it has been shown that endurance training significantly increases ER(alpha) mRNA levels in the female rat gastrocnemius muscle. The aim of this study was to determine if this training programme also modifies ER(alpha) mRNA levels in muscles with different typology, the soleus (slow twitch muscle), extensor digitorum longus (fast twitch muscle) and gastrocnemius (intermediate muscle). So far, two groups of Wistar female rats were set up: untrained (u) (n = 7), and trained (e) (n = 7). The endurance training programme was performed for 7 weeks, 5 days per week and consisted of 1 h of continuous running on an adapted motor-driven treadmill involving progressive intensity and gradient of the treadmill. Three different skeletal muscles, extensor digitorum longus (E), gastrocnemius (G) and soleus (S), were isolated and weighed in the untrained (Eu, Gu and Su) and trained group (Ee, Ge and Se). Semi-quantification of ER(alpha) mRNA levels was performed by the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. In order to attest the efficiency of our endurance training programme, the citrate synthase activity (CS) of each muscle was measured by a fluorimetric method. The CS activity was significantly increased with training in the gastrocnemius [100.00 +/- 4.99% in Gu (n = 6) vs. 138.10 +/- 8.82% in Ge (n = 6), P < 0.01] and in the soleus [100.00 +/- 2.92% in Su (n = 7) vs. 115.90 +/- 3.71% in Se (n = 7), P < 0.01] but not in the extensor digitorum longus [100.00 +/- 1.87% in Eu (n = 7) vs. 96.90 +/- 1.55% in Ee (n = 7)]. Concerning the influence of muscle type on ER(alpha) mRNA level (1) in the untrained group, the ER(alpha) mRNA level was significantly higher in soleus muscle compared with gastrocnemius and extensor digitorum longus muscles [0.43 +/- 0.04 in Su (n = 7) compared with 0.31 +/- 0.03 in Gu (n = 6) and 0.21 +/- 0.03 in Eu (n = 7), P < 0.05; P < 0.05); 2] in the trained group, the ER(alpha) mRNA level was significantly higher insoleus and gastrocnemius muscles compared with extensor digitorum longus muscle [0.43 +/- 0.06 in Se (n = 7) and 0.49 +/- 0.05 in Ge (n = 6) vs. 0.12 +/- 0.01 in Ee (n = 7), P < 0.05; P < 0.05]. Indeed, after training, the ER(alpha) mRNA level significantly increased in gastrocnemius muscle [0.31 +/- 0.03 in Gu(n = 6) vs. 0.49 +/- 0.05 in Ge (n = 6), P < 0.01], significantly decreased in extensor digitorum longus [0.21 +/- 0.03 in Eu (n = 7) vs. 0.12 +/- 0.01 in Ee (n = 7), P < 0.01] and was not significantly modified in soleus [0.43 +/- 0.04 in Su (n = 7) vs. 0.43 +/- 0.06 in Se (n = 7)]. The differences in ER(alpha) mRNA level between trained and untrained animals indicate training-induced effects that are specific to the skeletal muscle type.

Animals↗

PubMed2002

[Medium-term results of multisite biventricular stimulation in severe cardiac failure].

Since its introduction in cardiac failure in 1994, biventricular cardiac stimulation has been widely applied with many clinical trials and the development of new specific technology. The authors present the results observed in the first 125 consecutively implanted patients at the Rennes University Hospital. After a mean follow-up of 22 months, the mortality rate was 40%. The causes of death were sudden death in 42% of patients, progression of cardiac failure in 34% and non-cardiac in 24%. The functional benefits of biventricular cardiac stimulation were seen through significant improvement in HYHA Class, 3.3 +/- 0.5 before implantation to 2.3 +/- 0.8 at the end of follow-up, and by a significant increase of 40% of peak VO2 and of maximal duration of exercise. With the learning curve and development of new technology, the left ventricular catheterisation via a coronary sinus vein, increased from 56% to over 95% during the last two years with an acceptable rate of complications. These results, with the reserve of not being a controlled trial, show the feasibility, safety and efficacy of biventricular cardiac stimulation in terms of functional benefit. Clinical trials are currently underway to assess the impact of this method on morbi-mortality and to assess the concept in association with ventricular defibrillation.

Aged↗

PubMed2002

[Magnetocardiography: principles and potential uses in cardiology].

Magnetocardiography (MCG) is a non-invasive technique of studying cardiac electrophysiology activity. It appears that electric and magnetic measurements are not only complementary but provide independent information. Described over 25 years ago, recent technical progress in the field of supraconductivity has provided MCG with real clinical applications. It is still mostly used in research, but its clinical applications are beginning to develop. The most interesting clinical application of the MCG is certainly its capacity to provide a non-invasive anatomical localisation of the arrhythmogenic substrate or of accessory pathways. Nowadays, however, the accuracy of these localisations needs to be improved. When this has been accomplished, MCG could play a significant role in non-invasive cardiological investigation with well-defined clinical applications.

Arrhythmias, Cardiac↗

PubMed2002

[Exercise-induced laryngomalacia].

Exercise-induced laryngomalacia is a rare differential diagnosis of exercise-induced asthma. We report the case of a previously fit 14-year-old female patient who presented with dyspnoea on intense exertion and whose condition had not improved with treatment prescribed for a misdiagnosed exercise-induced asthma. A diagnosis of exercise-induced laryngomalacia was eventually made when a variable extra-thoracic airway obstruction on the flow-volume loops was obtained after an incremental exercise test. Flexible fiberoptic rhinolaryngoscopy confirmed this abnormality and demonstrated an anterior prolapse of the arytenoid region, partially obstructing the airway. The patient therefore underwent laser aryepiglottoplasty which produced a satisfactory anatomical outcome in the larynx but which only resulted in a partial functional improvement. Laryngomalacia is rare and its pathophysiology is not well understood. However, it should be considered in patients presenting with exertional dyspnoea, particularly if there is inspiratory embarrassment, who fail to improve with beta-2-adrenergic agonists. The diagnosis can be made from the flow-volume loop and direct laryngoscopy, before and after exercise.

Adolescent↗

PubMed2001

[Physiopathology of exercise-induced arrhythmias].

Physical exercise induces a big stress upon the cardiovascular system. It increases dramatically myocardial oxygen consumption. Thus, many different nervous, hormonal and ionic adaptations are requested to respond to physical exercise stress. These adaptations can induce or conversely stop cardiac arrhythmias.

Adaptation, Physiological↗

PubMed2001

[Electrocardiographic features of the athlete: what are the limits?].

The athlete's heart syndrome concerns only high level trained subjects. The classical electrocardiographic features of this syndrome are hypokinetic arrhythmia as bradycardia, low level of atrioventricular and of right bundle branch block and electrocardiographic T wave alterations. Sometimes, marked ventricular repolarisation alterations can suggest the presence of heart disease. These electrocardiographic patterns seem linked to the alterations of the two drive of autonomic nervous system (sympathetic and parasympathetic) and to cardiac hypertrophy. In all cases, it must be kept in mind that the athlete must be free of clinical symptoms and that these electrocardiographic alterations must disappear during exercise and in case of physical training cessation. In case of doubt a cardiologist judgement must be performed.

Arrhythmias, Cardiac↗

PubMed2001

Contribution of the anomeric effect to the solution and crystal structure of [1S,2S,6S,7s]-1,6-diaza-4,9-dioxa-2,7-dimethoxycarbonylbicyclo[4.4.1]undecane, a condensation product of L-serine methyl ester with formaldehyde.

The reaction of L-serine methyl ester hydrochloride (1) with paraformaldehyde (2) in dichloromethane in the presence of triethylamine afforded a novel compound: [lS,2S,6S,7S]-1,6-diaza-4,9-dioxa-2,7-dimethoxycarbonylbicyclo[4.4.1]undecane (4) as a 2:3 adduct of 1 with 2. 1H and 13C NMR spectroscopy were unable to discriminate between two possible symmetrical structures. The latter was unambiguously proved by X-ray crystallography. The crystal structure established: (i) the existence of two identical seven-membered rings each containing a N-C-O grouping; (ii) the existence of a long C-O-C-N-C-N-C-O-C sequence in which each nitrogen belongs simultaneously to a N-C-O (oxazolidine) and to a N-C-N (aminal) motifs; (iii) the existence of a chair-like conformation for both seven-membered rings; (iv) the antiperiplanar geometry of pN-C-O and consequently the manifestation of a strong anomeric effect in both N-C-O groupings, whereas anomeric effect was virtually absent in the N-C-N sequence, as corroborated by bond distances and bond angles. Chemical shifts, coupling constants and NOE effects confirm that the conformational features of 4 are preserved in solution.

Bridged Bicyclo Compounds, Heterocyclic↗

PubMed2001

Influence of atenolol on the kinetics of RT interval rate adaptation in conscious dogs.

The objective was to test an effect of atenolol independent of heart rate on electrocardiographic RT rate adaptation by investigating RT adaptation during spontaneous rate and after an abrupt change of atrial rate (study of RT delay). Digital electrocardiograms were recorded from eight conscious dogs. Analysis of RT interval (measured from QRS apex to end of T) was performed on a beat-to-beat basis. The protocol was repeated in the control state and after atenolol administration (2 mg/kg). Regarding spontaneous heart rate, an increased or decreased RR duration did not modify the beat-to-beat relative adaptation of RT to a change of RR (2.15 +/- 1% during control). Atenolol increased mean RR (p < 0.001) and decreased relative adaptation of RT (0.22 +/- 0.18%, p < 0.001). The inverse correlation between mean RR and the relative RT adaptation (r = -0.76, p < 0.05) disappeared after atenolol administration. Regarding RT delay, complete adaptation of RT required 3 min; 48 +/- 16% of this adaptation was observed after the first beat and 60 +/- 11% was observed after the 20th. Atenolol attenuated this adaptation during the first six beats following the abrupt cycle length change (p < 0.05). We concluded that the attenuation of RT rate adaptation after atenolol is related to heart rate modulation and to the time delay in RT rate adaptation.

Adaptation, Physiological↗

PubMed2000

Anomeric effects in non-carbohydrate compounds: conformational differences between the oxazolidine rings of a cis-fused bicyclic system.

Tris(hydroxymethyl)aminomethane (Tris) can react with benzaldehyde (1:2 molar ratio) to produce cis-2,8-diphenyl-5-hydroxymethyl-1-aza-3,7-dioxabicyclo[3.3.0]octa ne, the structure of which has been confirmed by nuclear magnetic resonance spectroscopy and X-ray crystallography. The crystal structure showed that both oxazolidine rings A and B are puckered in opposite directions. Ring A exists in an E3 envelope form with 0-3 noticeably down (0.65 A) the plane of the remaining atoms, whereas ring B adopts the 7E envelope conformation with the 0-7 atom displaced up from the mean reference plane by 0.70 A. Comparison of bond angles and bond distances showed that both oxazolidine rings A and B exhibit cross endo-anomeric effects resulting from electron delocalization over the bond sequence O-3-C-2-N-1-C-8-O-7.

Bridged Bicyclo Compounds, Heterocyclic↗

PubMed2000

Cardiac loading conditions modify the ventricular repolarization in conscious dogs with heart failure.

Changes in myocardial loading conditions influence the ventricular action potential via mechanoelectric feedback, a mechanism impaired in pathology. In vivo the QT interval of the electrocardiogram which reflects the action potential duration allows appropriate determination of its modifications. The effects of changes in cardiac loading conditions (load reduction with trinitrin; volume loading with Plasmion) on regional function and ventricular local electrogram were investigated in conscious dogs before (control) and after 4 weeks of rapid pacing (dilated cardiomyopathy, DCM). In controls both interventions increased heart rate. Trinitrin increased end-diastolic wall thickness (EDWth, P<0.001) and reduced absolute QT interval duration (P<0.05). Plasmion decreased EDWth (P<0.001) and increased left ventricular end diastolic pressure (LVEDP, P<0.001) without QT interval alteration. However, the corrected QT interval was unchanged in both interventions. In DCM, trinitrin did not change the QT interval. Plasmion increased LVEDP (P<0.01) and prolonged QT and corrected QT intervals (P<0.01) despite the tachycardia. In controls the changes in cardiac loading conditions did not modify the QT interval, suggesting intact endogenous regulation of repolarization. The impaired adaptation observed in DCM contributed to an increase in QT interval following volume loading. In this model, a prolonged repolarization after abrupt volume loading may result from enhanced or disclosed mechanoelectric feedback.

Animals↗