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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.

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.

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.

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.