Otolith signals contribute to inter-individual differences in the perception of gravity-centered space.

The aim of the present study was to investigate (1) the relative contribution of the egocentric reference as well as body orientation perception to visual horizon percept during tilt or during increased gravito-inertial acceleration (GiA, hypergravity environment) conditions and (2) the role of vestibular signals in the inter-individual differences observed in these perceptual modalities. Perceptual estimates analysis showed that backward tilt induced (1) an elevation of the visual horizon, (2) an elevation of the egocentric estimation (visual straight ahead) and (3) an overestimation of body tilt. The increase in the magnitude of GiA induced (1) a lowering of the apparent horizon, (2) a lowering of the straight ahead and (3) a perception of backward tilt. Overall, visual horizon percept can be expressed as the combination of body orientation perception and egocentric estimation. When assessing otolith reactivity using off-vertical axis rotation (OVAR), only visual egocentric estimation was significantly correlated with horizontal OVAR performance. On the one hand, we found a correlation between a low modulation amplitude of the otolith responses and straight ahead accuracy when the head axis was tilted relative to gravity. On the other hand, the bias of otolith responses was significantly correlated with straight ahead accuracy when subjects were submitted to an increase in the GiA. Thus, straight ahead sense would be dependent to some extent to otolith function. These results are discussed in terms of the contribution of otolith inputs in the overall multimodal integration subtending spatial constancy.

Bioceramic fabrics improve quiet standing posture and handstand stability in expert gymnasts.

Bioceramic fabrics have been claimed to improve blood circulation, thermoregulation and muscle relaxation, thereby also improving muscular activity. Here we tested whether bioceramic fabrics have an effect on postural control and contribute to improve postural stability. In Experiment 1, we tested whether bioceramic fabrics contribute to reduce body-sway when maintaining standard standing posture. In Experiment 2, we measured the effect of bioceramic fabrics on body-sway when maintaining a more instable posture, namely a handstand hold. For both experiments, postural oscillations were measured using a force platform with four strain gauges that recorded the displacements of the center of pressure (CoP) in the horizontal plane. In half of the trials, the participants wore a full-body second skin suit containing a bioceramic layer. In the other half of the trials, they wore a 'placebo' second skin suit that had the same cut, appearance and elasticity as the bioceramic suit but did not contain the bioceramic layer. In both experiments, the surface of displacement of the CoP was significantly smaller when participants were wearing the bioceramic suit than when they were wearing the placebo suit. The results suggest that bioceramic fabrics do have an effect on postural control and improve postural stability.

Characterization of the nm23-M2, nm23-M3 and nm23-M4 mouse genes: comparison with their human orthologs.

The nm23 gene family is thought to be involved in physiopathological processes such as growth, differentiation and cancer promotion, progression or metastasis. We report here the mouse nm23-M3 and nm23-M4 complementary DNA sequences and the genomic cloning, characterization and tissue expression pattern of the nm23-M2, nm23-M3 and nm23-M4 genes, in comparison with their human and rat orthologs and with the human nm23-H1 and mouse nm23-M1 genes. The organization and structure of the members of this gene family are remarkably similar in human and rodents. Accordingly, the striking similarities between the human and mouse nm23 genes enable the use of mouse transgenic and knock-out models for studying the role of nucleoside diphosphate kinase isoforms in human physiopathology.

Balloon mitral commissurotomy for mitral restenosis after surgical commissurotomy.

Balloon mitral commissurotomy (BMC) was performed in 113 patients. Of these patients, 27 (24%) (25 women and 2 men, aged 49 +/- 13 years) had recurrent mitral stenosis 13 +/- 6 years (range 5 to 29) after surgical commissurotomy. Eleven patients (41%) were considered at high risk for surgery. BMC resulted in an increase in mitral valve area from 1.1 +/- 0.3 to 1.9 +/- 0.7 cm2 (p < 0.0001), and a decrease in mean mitral gradient from 16 +/- 7 to 6 +/- 3 mm Hg (p < 0.0001). An optimal result of BMC (increase in valve area > or = 25% with a post-BMC valve area > or = 1.5 cm2) was obtained in 18 patients (67%). The results did not differ from those observed in the 86 patients of our entire series without prior surgical commissurotomy. Patients with an optimal result of BMC had a more recent surgical commissurotomy and lesser morphologic alterations of the mitral valve than did those with a nonoptimal result. Patients with echocardiographic scores < 10 had an 80% success rate of BMC; however, this rate decreased to 29% for those with scores > or = 10. One patient (4%) died from a cerebrovascular accident. Clinical follow-up at 1 year showed persistent clinical improvement in 89% of patients with an optimal result of BMC; 72% were in New York Heart Association class I and 17% in class II.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term (9 to 33 months) echocardiographic follow-up after successful percutaneous mitral commissurotomy.

Late results after successful percutaneous mitral commissurotomy were assessed by prospective clinical and echocardiographic follow-up. Fifty-seven patients were followed for a mean of 19 +/- 6 months (range 9 to 33) after the procedure. Mitral valve area (measured by Doppler half-time method) increased from 1.0 +/- 0.2 to 2.2 +/- 0.5 cm2 immediately after commissurotomy, and then decreased to 1.9 +/- 0.5 cm2 at follow-up (p less than 0.05), whereas gradient did not change after its immediate postcommissurotomy reduction. Echocardiographic restenosis (mitral valve area less than or equal to 1.5 cm2 with greater than 50% reduction of initial gain) was seen in 12 of 57 patients (21%). Atrial shunting, detected by transthoracic color Doppler in 61% of patients immediately after the procedure (color flow jet through atrial septum), persisted in 30% at follow-up. Restenosis by univariate analysis correlated with age, smaller valve area after the procedure, and higher echocardiographic score. Multivariate analysis identified leaflet mobility and calcifications as the components of a score that was predictive for restenosis. Magnitude of shunt (pulmonary-to-systemic flow ratio greater than 1.5), use of a Bifoil balloon (2 balloons on 1 shaft), and smaller valve area after the procedure were predictors by multivariate analysis of the persistence of atrial shunting. Clinical improvement persisted at long-term follow-up (mean New York Heart Association class 1.6 +/- 0.6 vs 2.6 +/- 0.6 before commissurotomy). Improvement of greater than or equal to 1 functional class was seen in 75% of patients (80% of those without and 58% of those with restenosis); patients with a shunt did not differ from the entire group.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in visual search tasks between congenitally deaf and normally hearing adults.

In order to study the processes of central vision in deaf subjects, 12 congenitally deaf adults and 12 normally hearing adults performed a visual search task. The task consisted of detecting a "Q" target among "O" distractors in variable numbers and the reverse. The method used a paradigm based on the stimulus onset asynchrony (SOA) specifically designed to measure the visual processing time between the visual array and a mask. A different visual search pattern was observed in each group. The hearing subjects showed an asymmetrical visual search pattern (parallel versus serial processing respectively for "Q" and "O" targets). In contrast, the deaf subjects showed a symmetrical search pattern (parallel processing in both experimental conditions). In a visual task selectively supported by central vision, visual processes of the congenitally deaf are more efficient when the task involves the contribution of serial processes.

Traumatic aortic ruptures diagnosed by transesophageal echocardiography.

The aim of this study was to determine the diagnostic efficiency of transesophageal echocardiography (TEE) in isthmic aortic ruptures and to describe the echocardiographic Doppler anomalies. TEE was performed prospectively for 18 months in 33 patients with serious polytraumas requiring intensive care. The average age was 40.75 years (range, 17 to 78 years). Single or biplanar TEE was used. In three patients with aortic transection, echocardiography showed an intimal flap thicker than that of dissections. The flaps were torn and retracted on the free edge. It was difficult to distinguish the periaortic hematoma. Doppler imaging showed turbulent flows in several places around the aorta. These flows were especially visible at the beginning of the intimal flap. They were visible on M-mode color imaging during systole and diastole. During diastole, a large color flow was observed in the middle of the aortic lumen. It was turbulent in some places and mimicked the systolic filling of the aorta. These flows create the characteristic "to and fro sign" spectrum of Doppler imaging, usually seen in peripheral false arterial aneurysms. TEE findings were confirmed in two cases by surgery and in one case by aortography. TEE seems to be an effective means of detecting isthmic rupture, with the diagnosis resting on the data obtained from echocardiography and Doppler imaging. A suspected isthmic disruption should be assessed by an emergency TEE and aortography used only for uncertain or complex cases.

Effects of fluid ingestion on cognitive function after heat stress or exercise-induced dehydration.

This study investigated the effects of heat exposure, exercise-induced dehydration and fluid ingestion on cognitive performance. Seven healthy men, unacclimatized to heat, were kept euhydrated or were dehydrated by controlled passive exposure to heat (H, two sessions) or by treadmill exercise (E, two sessions) up to a weight loss of 2.8%. On completion of a 1-h recovery period, the subjects drank a solution containing 50 g l(-1) glucose and 1.34 g l(-1) NaCl in a volume of water corresponding to 100% of his body weight loss induced by dehydration. (H1 and E1) or levels of fluid deficit were maintained (H0, E0). In the E0, H0 and control conditions, the subject drank a solution containing the same quantity of glucose diluted in 100 ml of water. Psychological tests were administered 30 min after the dehydration phase and 2 h after fluid ingestion. Both dehydration conditions impaired cognitive abilities (i.e. perceptive discrimination, short-term memory), as well as subjective estimates of fatigue, without any relevant differences between the methods. By 3.5 h after fluid deficit, dehydration (H0 and E0) no longer had any adverse effect, although the subjects felt increasingly tired. Thus, there was no beneficial effect of fluid ingestion (H1 and E1) on the cognitive variables. However, long-term memory retrieval was impaired in both control and dehydration situations, whereas there was no decrement in performance in the fluid ingestion condition (H1, E1).

Subjective vertical and postural activity.

Three experiments were conducted to test the effect of postural information, resulting from the active control of balance, on the perception of the vertical. Subjects were required to adjust a luminous rod in two different visual contexts: in the dark or within a tilted visual frame. In these experiments, postural activity was manipulated by placing observers either in a situation of slight postural imbalance (Experiment 1) or in a situation of postural immobilization (Experiment 2). In both situations performance was compared with a control condition in which subjects were standing upright freely (Experiment 1) or sitting unconstrained (Experiment 2). Results showed no main effect of active posture or of immobilization on the visual perception of the vertical. In the third experiment, subjects were supine with their Z body axis perpendicular to the plane of the luminous rod. Thus, body orientation relative to gravity was modified and motor activity reduced. In this position, the physical vertical was perceived quite accurately in a dark environment. Moreover, in the titled frame condition, the supine body position clearly improved vertical judgements. These results are discussed in relation to the ecological theory of orientation.

Effects of gymnastics expertise on the perception of body orientation in the pitch dimension.

The purpose of this study was to investigate how experts in motor skills requiring a fine postural control perceive their body orientation with few gravity based sensory cues. In Experiment 1, expert gymnasts and controls had to detect their body tilt when pitching at a velocity of 0.05 deg.s(-1), in two conditions of body restriction (strapped and body cast altering the somatosensory cues). Contrary to the experts, the controls exhibited a larger body tilt when totally restrained in the body cast. In Experiment 2, subjects had to estimate their Subjective Postural Vertical (SPV) starting from different angles of pitch tilt. The controls exhibited significant errors of SPV judgement whereas the experts were very precise. These results suggest that 1) somatosensory cues are more informative than otolithic cues for the perception of body orientation, and 2) the efficiency of otolithic and/or interoceptive inputs can be improved through a specific training to compensate for the lack of somatosensory cues.

[Immediate results and mid-term follow-up after percutaneous mitral valve replacement]. / Résultats immédiats et suivi à moyen terme après valvuloplastie mitrale percutanée.

Percutaneous mitral valvuloplasty (PMV) was performed by the anterograde transseptal approach (double balloon technique) in 154 patients with symptomatic mitral stenosis. The mean age of the patients was high (53 +/- 14 years), 87% were women, 68% were in functional Classes III or IV of the NYHA and 37 (24%) had previously undergone surgical commissurotomy. The echocardiographic score was 8.5 +/- 1.6. PMV could not be completed because of a technical failure or a complication in 14 cases (9%). In the other patients, PMV increased mitral surface area from 1.0 +/- 0.3 to 2.0 +/- 0.8 cm2 (p less than 0.0001). A haemodynamic success (greater than or equal to 25% increase in mitral surface area and final area greater than or equal to 1.5 cm2) was obtained in 104 patients (75%). The predicting factors of success were echocardiographic score (8.1 +/- 1.4 versus 9.4 +/- 1.7; p less than 0.0001) and cardiac output (4.0 +/- 1.1 versus 3.0 +/- 1.0/l/min; p less than 0.0001). The duration of the procedure, the technical failure rate and the frequency of cardiac perforation were influenced by the learning curve. The degree of mitral regurgitation increased after PMV in 34% of cases, usually by one grade and without clinical or haemodynamic consequences. Acute mitral regurgitation was a rare (3%) and impredictable complication. An interatrial shunt was demonstrated in 80% of cases after PMV but the Qp/Qs ratio rarely exceeded 1.5 (11%). This shunt disappeared or decreased in the majority of cases during follow-up. The clinical result was an improvement of at least one functional Class in 83% of cases at 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of subvalvular disease on results of percutaneous mitral valvotomy]. / Influence de l'atteinte de l'appareil sous-valvulaire sur les résultats de la valvulotomie mitrale percutanée.

In order to study the results of percutaneous mitral valvuloplasty (PMV), subvalvular mitral disease was classified using: 1) the transthoracic echo score (0-4), 2) an index derived from left ventricular angiography defined as the ratio of the distance from the extremity of the papillary muscle and the mitral valve in systole and the distance between the beginning of the aortic root and the apex of the left ventricle in diastole. This index of subvalvular fibrosis could be measured in 80 out of our first 103 PMV performed without complication; the mitral surface are a increased from 1.1 +/- 0.4 to 2.2 +/- 0.8 cm2 (p less than 0.0001). After PMV, mitral regurgitation was observed or was aggravated in 28 patients (35%), by one grade in 25 and by more than one grade in 3. The overall echo score was 8.3 +/- 1.5 and that of subvalvular fibrosis was 2 +/- 0.6. The angiographic index of subvalvular fibrosis was 0.18 +/- 0.04. No correlation was observed between echo and angiographic appreciation of subvalvular fibrosis. Multivariate analyses were selected: 1) the overall echocardiographic score (r = -0.45, p less than 0.0001), but not the angiographic index of subvalvular fibrosis or echocardiographic score of subvalvular fibrosis, was predictive of increase of valve surface area; 2) the absence of mitral regurgitation before PMV (p less than 0.01) and an angiographic index of subvalvular fibrosis less than or equal to 0.15 (p less than 0.03) were predictive of increased mitral regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Adaptation of the left ventricle function to exercise in aortic stenosis. Study with cavitary angioscintigraphy]. / Adaptation de la fonction ventriculaire gauche à l'effort au cours du rétrécissement aortique. Etude par angioscintigraphie cavitaire.

Eighteen patients with pure aortic stenosis without coronary artery disease underwent equilibrium radionuclide angiography to evaluate the adaptation of their left ventricular function to exercise. The left ventricular ejection fraction, peak left ventricular ejection, and fillings, and their timing were calculated from time-activity curves and their first derivatives at rest and at the maximum of exercise. There were no clinical complications. The ST segment and T wave changes of 14 patients were accentuated and 3 patients developed anginal pain. The ejection fraction was normal at rest and did not change significantly during exercise. The peak ejection did not vary but peak left ventricular filling was prolonged by exercise. There was a correlation between peak ventricular ejection at rest and the aortic valve surface area at catheterisation. This isotopic parameter was inversely correlated with LVEDP. There was a close correlation between age and peak ventricular filling on exercise. The variation between resting and exercise values of this parameter was inversely correlated with age. This study shows that exercise stress testing can be undertaken without risk in patients with aortic stenosis. The results of radionuclide angiography show that peak left ventricular ejection is a valuable parameter. The interpretation of the diastolic parameters is however more difficult because they are age-related.

[Immediate and mid-term results of percutaneous pulmonary valvotomy in adults. Apropos of 10 cases]. / Résultats immédiats et à moyen terme de la valvulotomie pulmonaire percutanée chez l'adulte. A propos de 10 cas.

Percutaneous pulmonary valvulotomy (PPV) is the treatment of choice for isolated congenital pulmonary stenosis of infancy. However, experience with this technique in the adult is much more limited. From November 1983 to November 1990, PPV was performed in 10 adults in our Institute. The mean age was 40 +/- 19 years (range 21 to 71 years). Before PPV, 4 patients were in functional Class II and 6 in functional Class III of the NYHA classification. All procedures were successful with no complications. The right ventricular systolic pressure decreased from 98 +/- 35 to 57 +/- 30 mmHg (p less than 0.01) and the mean pulmonary gradient decreased from 57 +/- 30 to 23 +/- 15 mmHg (p less than 0.01). The cardiac output was unchanged: 5.3 +/- 2.8 and 5.9 +/- 2.6 l/mn (not significant). Pulmonary valve area increased from 0.59 +/- 0.3 to 1.15 +/- 0.5 cm2 (p less than 0.01). The post-dilatation infundibular gradient was less than 10 mmHg in all patients. After an mean follow-up period of 29 +/- 26 months all but one patient (Class II) were in functional Class I. Exercise capacity was 6.9 +/- 2 Mets. Doppler echocardiography indicated a stable mean pulmonary gradient of 16.5 +/- 6.8 mmHg after PPV and 15.0 +/- 7.0 mmHg during follow-up. Pulmonary regurgitation was less than Grade I in all cases. In conclusion, PPV is an effective treatment for adult pulmonary stenosis and carries a low risk. The mid term results are excellent.

[Thrombolytic treatment of myocardial infarction. Data on the limitation of infarction size and left ventricular function]. / Traitement thrombolytique de l'infarctus du myocarde. Données sur la limitation de la taille de l'infarctus et fonction ventriculaire gauche.

Since its introduction in cardiovascular therapeutics, thrombolysis has established itself as an effective procedure of coronary reperfusion during the acute phase of myocardial infarction. Large scale clinical trials have demonstrated a clear cut reduction in mortality providing that the treatment is administered sufficiently early after the onset of symptoms. This reduced mortality is probably related to the limitation of infarct size and the conservation of ventricular function even though this relationship is not always analysed. Studies of infarct size and left ventricular function are difficult to perform and this is reflected in the number of different methods proposed. Apart from coronary reperfusion and its timing, other factors influence the definite size of the infarct, such as the development of a collateral circulation, the existence of cellular reperfusion lesions and the occurrence of reocclusion. The infarct size may be assessed by a number of methods, some simple (enzymes, electrocardiogram) but relatively inaccurate, others more promising but difficult to perform and more costly. Thallium 201 scintigraphy seems to be the best available method and our experience is based on these results. The reference method for the evaluation of left ventricular function is angiography but angioscintigraphy also provides information on global and regional function, the regional study being particularly valuable in the analysis of thrombolytic drug efficacy. A review of the literature shows that thrombolysis is associated with a reduction in infarct size compared with conventional therapy and with conservation of left ventricular function whichever thrombolytic agent is used.(ABSTRACT TRUNCATED AT 250 WORDS)

Perceptual thresholds of radial accelerations as indicated by visually perceived eye level.

The purpose of this study was to determine whether very low gravito-inertial forces produced by centrifugation affect the visually perceived eye level (VPEL) in the same way as the oculagravic illusion. Eleven subjects in total darkness were instructed to set a luminous target to the VPEL, either while they were motionless or undergoing very low centrifugation. Results showed a significant effect on VPEL at 0.01 m/s2 radial acceleration, which corresponds to a resultant gravito-inertial equal to 9.81001 m/s2. This radial acceleration value is lower than the lowest perception thresholds previously measured for a linear acceleration (about 0.05 m/s2). Thus, as previous results have shown that the oculogyral illusion indirectly decreases perceptual thresholds for the perception of angular acceleration in darkness, the lowering of the VPEL indirectly decreases thresholds for perception of radial acceleration produced by centrifugation. Moreover, there is a logarithmic relationship between very low centrifugation and the positioning of the VPEL at a lower level. This relationship is explained as a direct and sole effect on the sensory utricular otolithic membrane by the radial acceleration of centrifugation.

Cognitive performance during short acclimation to severe hypoxia.

BACKGROUND: Exposure to high altitudes requires acclimation or acclimatization, to prevent the negative effects of severe hypoxia. Among several methods, short acclimation with intermittent exposure to severe hypoxia in a hypobaric chamber triggers efficient physiological pre-adaptation mechanisms (11-13). However, we have little knowledge about the cognitive repercussions of such an acclimation protocol. METHODS: Four mountaineers were tested daily in the course of a short acclimation protocol (5 d). After their SaO2 (arterial oxyhemoglogin saturation) were recorded, they carried out a choice reaction time task (Manikin test) twice every day; first at ground level (250 m, control sessions), second at the highest altitude of the day (D1 = 5000 m, D2 = 5500 m, D3 = 6000 m, D4 = 6500 m, D5 = 7000 m). RESULTS: High altitude SaO2 level decreased during the first 3 d, then stabilized around 72-73%. Despite a slight and transient increase at the highest altitude relative to the ground level in D4, the error rate remained low throughout the protocol. Further, response time to the Manikin task did not show significant changes among the days during the acute stage of hypoxia relative to ground level up to 7000 m. CONCLUSIONS: On the whole, it seems that a short acclimation protocol based on intermittent exposure to simulated high altitudes triggered adaptive processes without major impairment in a choice reaction time task during the acute stages of severe hypoxia.

[Vasospastic angina with angiographically normal coronary vessels of iatrogenic origin. Apropos of 2 cases]. / Angor vasopastique à coronaires angiographiquement normales d'origine iatrogène. A propos de deux nouvelles observations.

Two cases of angina pectoris, induced by methylergometrine (Methergin) and by an association of ergotamine tartrate (Gynergene) and methysergide (Desernil) respectively, are reported. In both patients, angiography revealed spontaneous spasm in a coronary system free from any significant atheromatous stenosis. In the second case, a test administration of i.v. Methergin, administered during calcium-channel antagonist treatment a few days after the "guilty" drugs had been stopped was found to be negative. The outcome was favorable in both cases: the angina disappeared and the base-line and exercise ECG returned to normal. The hypothesis of coronary spasm induced by the treatment was adopted in both cases. In this context, the major iatrogenic etiologies of vasospastic angina are recalled, together with the prophylactic and therapeutic measures they call for.

Strobe frequency in the rod and frame effect.

This experiment dealt with the role of strobe frequency on the rod and frame effect in frame-dependent and frame-independent subjects in light of the destabilizing effect of strobe lighting on body posture. Analysis showed that the frame effect was resistant to strobe illumination and was significantly stronger at 2 Hz than at 9 Hz. Since the stroboscopic effect was not related to the extent of the frame effect observed in normal light, there was no over-all dependence on the different components of the visual field (static and kinetic). Moreover, analysis of eye movements during stroboscopic exposure confirmed previous observation of a visual scanning style related to orienting activity.

[Primary hypertrophic cardiomyopathies. Diagnosis and treatment]. / Les myocardiopathies hypertrophiques primitives. Diagnostic et traitement.

Hypertrophic cardiomyopathy (HCM) is currently considered to be a condition characterised by abnormal diastolic function, sometimes associated with left ventricular outflow obstruction which appears to be a secondary phenomenon. It is important to avoid overlooking this diagnosis especially in young subjects, because of the risk of sudden death, but conversely, false positive diagnosis can result in a serious social and psychological handicap. Echocardiography has assumed a major role in the diagnosis and follow-up of HCM over the last decade. It allows analysis of the localisation, extension and severity of the septal hypertrophy and of the mechanism of systolic anterior motion of the mitral valve. Cardiac doppler completes the non-invasive assessment of this condition by demonstrating the presence or absence of outflow tract obstruction, evaluating diastolic dysfunction, and documenting mitral and occasionally aortic valve regurgitation. Only severely symptomatic patients who do not respond to high dose medical therapy and for whom surgery might be an option need cardiac catheterization. Strenuous physical activity and sport are not recommended in asymptomatic forms. It is vital to identify those patients at high risk of sudden death (family history of sudden death, 48 to 72 hour Holter monitoring). In the absence of silent arrhythmias, preventive therapy should be more general in patients under 30 years of age. Despite a better understanding of the disease, the indications of medical and surgical treatment remain controversial and poorly defined. Treatment is mainly medical with Propranolol as the drug of choice. The dosage has to be tailored for each individual patient.(ABSTRACT TRUNCATED AT 250 WORDS)