The disynaptic group I inhibition between wrist flexor and extensor muscles revisited in humans.

The present studies are designed to further characterise the interneuronal pathway mediating the disynaptic reciprocal group I inhibition between flexors and extensors at the wrist and the elbow levels in humans. In the first series of experiments, we compared the electrical threshold of the reciprocal group I inhibition at the wrist and the elbow level after a prolonged vibration aimed at raising the electrical threshold of the antagonistic activated Ia afferents. Prolonged vibration to the 'conditioning' tendon, which raised significantly the electrical threshold of the inhibition at the elbow level, did not alter it at the wrist level. These results suggest that the dominant input to the relevant interneurones is Ia in origin at the elbow level but Ib in origin at the wrist level. In the second series of experiments, using the spatial facilitation method, we compared the effects on the post-stimulus time histograms of single voluntarily activated motor units of two volleys delivered both separately and together to group I afferents in the nerves supplying the homonymous and antagonistic muscles. At the wrist, but not at the elbow level, the peak of homonymous monosynaptic group I excitation was reduced on combined stimulation, although the antagonistic IPSP was just at the threshold. Because the suppression did not involve the initial bins of the peak, it is argued that the suppression is not due to presynaptic inhibition of Ia terminals, but probably reflects convergence between the homonymous and antagonistic volleys onto the interneurones mediating the disynaptic inhibition. Taken together with the previously reported effects of recurrent inhibition on reciprocal inhibition, these results suggest that inhibition between flexors and extensors is differently organised at the elbow (reciprocal Ia inhibition) and the wrist (non-reciprocal group I inhibition) levels. It is argued that the particular connectivity at the wrist level might correspond to some functional requirements at this ball joint.

Post-activation depression in various group I spinal pathways in humans.

This investigation was designed to study the effects of post-activation depression in different spinal pathways fed by group I afferents available to investigation in human subjects. It was precipitated by a recent investigation in the cat showing that-contrary to the general assumption-post-activation depression is not a widespread phenomenon in the spinal cord. In 24 healthy subjects comparison was made between the effects of low and high-test stimulus rates on the monosynaptic Ia excitation, known to be subject to post-activation depression, and on oligosynaptic pathways fed by group I afferents. Both the amplitude of monosynaptic H reflexes and the amount of heteronymous monosynaptic Ia facilitation were significantly smaller at high than at low-test stimulus rates (1-2 s compared with 6-8 s between two consecutive stimuli). So was the amount of reciprocal Ia inhibition of tibialis anterior motoneurones. In contrast, the amount of other non-monosynaptic group I effects directed to the same motor nuclei (peroneal-induced excitation of quadriceps motoneurones, disynaptic non-reciprocal group I inhibition of flexor carpi radialis motoneurones, and D1 inhibition of flexor carpi radialis and soleus H reflexes) were enhanced at high stimulus rates. Results in humans confirm that post-activation depression depends on the type of group I afferents, and/or on the target neurones. The functional significance of the discrepancy between post-activation depression in pure Ia pathways and in other group I pathways is discussed with regard to the fusimotor-driven servo-assistance from Ia afferent discharges.

[The methods for screening pulmonary hypertension related to systemic sclerosis in France. Descriptive survey of the French Research Group on Sclerosis]. / Pratiques françaises pour le dépistage de l'hypertension artérielle pulmonaire associée à la sclérodermie systémique. Enquête descriptive du Groupe de Recherche Français sur la Sclérodermie.

CONTEXT AND OBJECTIVES: Pulmonary hypertension (PHT) represents one of the severest complications and is life-threatening for patients suffering from systemic sclerosis (SSc). In France, the modalities for screening and treating PHT related to SSc are not well codified and no consensus has been reached. We conducted a survey among physicians inscribed on the list of the French Research Group on Sclerosis (GRFS - Groupe de Recherche Francais sur la Sclerodermie) to gather information on the status of the management of PHT related to SSc. METHODS: In 2002, we sent a questionnaire to 160 physicians, members of the GRFS, to assess the epidemiology and clinical profile of SSc patients as well as the modalities of screening and management of PHT in these patients. RESULTS: Eighty-eight physicians in 71 centres replied to the questionnaire. Each centre followed-up a mean of 33 SSc patients, with a global distribution of 53% limited and 47% diffused SSc. These physicians saw a mean of 5 new cases of SSc per year. The patients had been referred by town practitioners (53%) or from the hospital (47%). The mean number of SSc patients with PHT was of 5.1 per physician (1.5 new SSc + PHT patients per year). Almost all the centres (65/67) who replied systematically screened for PHT in SSc patients using Doppler echocardiography a mean of every 1.3 years. For the management of the patients exhibiting PHT, the majority (41/63) of centres collaborated with a specialized unit. Around one third of the centres treated these patients with calcium channel inhibitors (82%) and/or prostacyclin (90%). All the patients were followed-up by Doppler echocardiography. The majority of the physicians (72%) were interested in a research protocol on the subject and each could have included 4 patients, i.e., a total of 160. CONCLUSION: Pulmonary hypertension, a severe complication of SSc is screened for by the physicians of the GRFS using echocardiography with a frequency similar to Who guidelines (1.3 versus once/year).

Evidence for recurrent inhibition of reciprocal inhibition from soleus to tibialis anterior in man.

Reciprocal inhibition between ankle flexors and extensors has been the subject of numerous studies in Man. They have demonstrated that this reciprocal inhibition is in all likelihood caused by a disynaptic pathway at least partly fed by Ia afferents. It is thus generally agreed that this reciprocally organized inhibition between ankle flexors and extensors in Man is similar to the reciprocal Ia inhibition described in the cat. This conclusion has, however, been challenged, when Jankowska and McCrea described in the cat a non-reciprocal group I inhibition involving interneurones co-excited by Ia and Ib afferents and mediating inhibition to both antagonistic and non-antagonistic motoneurones. The only way to distinguish between reciprocal Ia inhibition and non-reciprocal group I inhibition is to test if the inhibition is blocked by recurrent inhibition, since only Ia interneurones are inhibited by recurrent inhibition. In the present study, reciprocal inhibition from soleus to tibialis anterior was thus investigated following activation of soleus-coupled Renshaw cells in normal human subjects. It was found that reciprocal inhibition induced in tibialis anterior motoneurones by the activation of soleus group I afferents is deeply depressed by activation of soleus-coupled Renshaw cells. This finding provides the missing data to identify disynaptic inhibition between antagonistic ankle muscles as a reciprocal Ia inhibition.

[Severe Moorens ulcer: efficacy of monthly cyclophosphamide intravenous pulse treatment]. / Ulcères de Mooren sévères: efficacité du traitement par cyclophosphamide en bolus intraveineux mensuels.

PURPOSE: Mooren's ulcer (MU) is a chronic peripheral corneal ulceration featuring conjunctival immunoglobulin deposits. It is considered as the result of a limbic immune process with hyperactivation of T and B lymphocytes. The etiology remains unknown. The response to topical steroid therapy and surgical procedures usually poor and the visual outcome can be devastating. METHODS: Clinical follow-up of 3 patients who had rebel MU to conventional therapy, and were treated with 1g monthly intravenous cyclophosphamide. RESULTS: First patient was a 24-years-old man who had MU in his left eye. The response to surgical procedure and intravenous steroid treatment was poor and corneal perforation occurred. The affected cornea healed after 9 months of Cy treatment. The second patient was a 50-years-old man who had MU in his left eye, which did not improved with lamellar keratoplasty and topical steroid therapy. Corneal healing was obtained after 20 months of Cy treatment. The third patient was a 70-years-old man who presented with a furrowed MU in his right eye which healed with conjunctival resection and 4 months of Cy perfusion. No adverse effects of Cy was noted as opposed to Cy given orally. CONCLUSION: We report the effectiveness of 1g monthly intravenous cyclophosphamide (Cy) treatment in rebel MU. We suggest that immunosuppressive therapy using IV monthly Cy may be proposed in severe rebel MU.

Modulation of presynaptic inhibition of la afferents during voluntary wrist flexion and extension in man.

Changes in presynaptic inhibition of Ia terminals directed to flexor carpi radialis (FCR) motoneurones (MNs) were investigated in normal human subjects at rest and during voluntary wrist flexion and extension. To that end, two independent methods were used: (1) the radial-induced D1 inhibition of the FCR H reflex, which assesses the excitability of PAD (primary afferent depolarisation) interneurones controlling presynaptic inhibition of Ia terminals mediating the afferent volley of the FCR H reflex; and (2) the heteronymous monosynaptic Ia facilitation induced in the FCR H reflex by intrinsic muscle Ia afferent stimulation, which assesses the ongoing presynaptic inhibition of Ia terminals. With respect to results at rest, it was found that at the onset of (and during tonic) voluntary wrist flexion, D1 inhibition was reduced and heteronymous monosynaptic Ia facilitation was increased. This suggests that, as in the lower limb, presynaptic inhibition is decreased on Ia terminals projecting to MNs involved in the voluntary contraction. In contrast with results observed in the lower limb, presynaptic inhibition of Ia terminals to FCR MNs was also found to be reduced at the onset of a voluntary contraction involving the antagonistic wrist extensors, suggesting that presynaptic inhibition of Ia terminals projecting to wrist flexors and extensors might be mediated through the same subsets of PAD interneurones. This is in keeping with other features showing that the organisation of reflex pathways between wrist flexors and extensors differs from that observed at other (elbow, ankle) joints.

[Coxiella burnetii pneumopathy on return from French Guiana]. / Pneumopathie à Coxiella burnetii au retour de Guyane française.

Q fever is a worldwide zoonosis but is not often a common cause of fever among travellers returning from the tropics. We report a case of acute Q fever, revealed by a pneumonia and acquired by a traveller in French Guyana. The chest radiography showed alveolar opacities and pleural effusion. Biological abnormalities were elevated liver enzyme levels and thrombocytopenia. The patient improved or the third day of antibiotic treatment. She mentioned that 3 other people she lived with during her trip had been diagnosed with Q fever. A common source outbreak was then suspected. They all stayed in the same farm in French Guyana. Animal exposure occurred there, in particular with a goat and a dog (both were parturient). The disease was probably transmitted by airborne dust to our patient, as no other vectors of transmission were found. Since the clinical presentation of Q fever is not specific, in order for the physician to diagnose it, he must have an awareness of the disease. Our case emphasised that looking for risk factors of Coxiella burnetii exposures is particularly important. Amongst them, the most important seems to be contact with farm animals. The clinician should thus try to trace such a possible contact when treating a case of traveler's Q fever.

Application of neural network calibrations to an halide ISE array.

The Neural Network (NN) technique was applied to the calibration of an ion selective electrode (ISE) array comprising a bromide selective electrode, two chloride ISEs and one thiocyanate ISE. The measured samples were synthetic mixture solutions of chlorides and bromides in concentration ranges such that interference occurs. The NN method allowed to perform the calibration without estimating the coefficients of the Nikolskii-Eisenman theoretical relation. Only the determination of bromide was detailed. The results obtained using this method were better than those obtained using linear multivariate calibration methods.

Halide ion-selective electrode array calibration.

The calibration of several ions (Cl(-), Br(-), F(-) and OH(-)) measured with an ion selective electrodes (ISE) array has been carried out in the presence of interferents using an experimental design and multivariate calibration methods. Partial least squares regression and principal component regression do not seem to improve the test set prediction compared to multivariate linear regression. In the case of very slight or no interference on the ISE, each ion can be determined using the corresponding ISE and univariate calibration methods, but the use of multivariate methods does not lead to worse results.

[Renin secreting tumor and severe hypertension. Apropos of a new case]. / Tumeur à rénine et hypertension artérielle sévère. A propos d'un nouveau cas.

A renin-secreting tumour has been observed in a 32-year-old female with severe hypertension known for 17 years. The excision of the tumour lead to the complete normalisation of the blood pressure. Histological examination showed that the tumour was benign, contained secretion granules at different stages of maturation, and derived from the juxta-glomerular apparatus. After reviewing the 40 cases previously reported in the literature we discuss the clinical presentation of this type of tumour and the approach to their diagnosis.

[Value of the lateral chest x-ray in the diagnosis of traumatic pleural effusions]. / Intérêt du cliché thoracique de profil dans le diagnostic des épanchements pleuraux traumatiques.

Forty patients were admitted to a hospital emergency department after closed chest injury. Chest X-rays, a-p and lateral, with low and high voltage, were performed in a supine position. The aim of the study was to show the interest of lateral films in the diagnosis of post-traumatic pneumo- and hemothoraces. A special technique, using a double-drawer plate holder, gave a good quality radiograph in emergency conditions without danger for patients with severe trauma. In 30 of the patients, chest radiographs confirmed pleural gas or blood collection. In ten of these, the diagnosis could only be made after radiographic examination. In nine other cases, radiographs showed an absence of hemo- or pneumothorax. Lateral views were very important in confirming a hemothorax and appreciating its volume, as well as in showing up partial pneumothoraces which could not be seen on a-p views. The interest of performing a lateral film in all the cases of chest injury is pointed out.

[Role of antigens and adjuvant substances in the histological response in experimental granulomas (immunogenic granuloma)]. / Rôle des antigènes et des substances adjuvantes dans la réponse histologique au cours de granulomes expérimentaux ("granulome immunogène").

The injection in rabbits of vaccinal antigens combined with immunity adjuvants (in particular calcium phosphate) causes a local lesion in which it is possible to recognize histologically, after a transitory afflux of polymorphonuclear leukocytes, a central area of adjuvant deposit, a middle area of histiocytes and monocytes, and a peripheral immunogenic area of lymphocytes and plasmocytes. These two cellular zones are rich in highly fluorescent cells in the presence of an antiglobulin serum with an embedding technique which respects to the upmost the structures and immunoreactivity of the cells. These histological features are not completely observed on the separate injection of antigen or adjuvant. They must be interpreted, after a fleeting non-specific reaction, while taking into account the still poorly understood method of action of the inorganic adjuvant and spread of the antigen in the organism.

[Results of a survey on post-transfusional malaria in France between 1960 and 1974]. / Résultats d'une enquête sur le paludisme post-transfusionnel en France entre 1960 et 1974

This inquire demonstrated that transfusion malaria was not so rare as we thought. So 56 cases have been numbered between 1960 and 1974, and probably they do not reflect exactly the real situation. In our country, plasmodium falciparum, specifically responsible of the most serious accidents, is the form most frequently incriminated and its frequency increases among the years: 76,1% of the infects between 1970 and 1974. At last we have confirmed that a prevent of those accidents must consider as a subject any one having resided in an impaluded country, and that implies a constant knowledge of the epidemiologic map of this parisitism. This prevent will be increased so that the transfusion malaria will not get a illness disease in France.

[Different pathogenic power of the original BCG strain of the Pasteur Institute and of an isoniazid resistant strain. Histopathological study and significance of local abscesses after inoculation of guinea pig]. / Pouvoir pathogène différent de la souche de BCG historique de l'Institut Pasteur et d'une souche isoniazido-résistante. Etude histopathologique et signification des abcès locaux après inoculation au cobaye

The inoculation into guinea pigs of 10 mg of BCG, obtained either from the Pasteur Institute original strain, or from a mutant isoniazid resistant strain, B1 catalase positive, caused in 40.4% of cases, the onset of abscesses at the point of injection. The frequency and course of these abscesses appear quite different with the two strains, 92.8% with the classical strain, persisting in more than half of the cases after one year, and 23.5% with the INH-resistant strains which regressed within 6 months. Histologically, the structure of the recent abscesses, with a large histiocytic wall often rich in bacteria, and a very cellular necrotic content, appears different from that of old abscesses with a thin wall and a heterogeneous content, calcification with reaction to foreign bodies, and presence of granules due to the persistance of bacteria. The INH-resistant strain is thus in the guinea pig, less aggressive and more rapidly eliminated than the classical Pasteur strain. The course and morphology of abscesses in guinea pigs are very similar to certain old lesions of human tuberculosis and involve, in all strains, phenomena of cell immunity both general and local.