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RhBG, a human member of the Amt/Mep/Rh/superfamily of ammonium transporters, has been shown to facilitate NH(3) transport and to be anchored to the basolateral plasma membrane of kidney epithelial cells, via ankyrin-G. We showed here that triple alanine substitution of the (419)FLD(421) sequence, which links the cytoplasmic C-terminal domain of RhBG to ankyrin-G, not only disrupted the interaction of RhBG with the spectrin-based skeleton but also delayed its cell surface expression, decreased its plasma membrane stability, and abolished its NH(3) transport function in epithelial cell lines. Similarly, we demonstrated that both anchoring to the membrane skeleton and ammonium transport activity are regulated by the phosphorylation status of the C-terminal tail of RhBG. Tyrosine 429, which belongs to the previously reported YED basolateral targeting signal of RhBG, was demonstrated to be phosphorylated in vitro using purified Src and Syk kinases and ex vivo by analyzing the effect of pervanadate treatment on wild-type RhBG or Y429A mutants. Then, we showed that Y429D and Y429E mutations, mimicking constitutive phosphorylation, abolished NH(3) transport and enhanced Triton X-100 solubilization of RhBG from the cell membrane. In contrast, the nonphosphorylated/nonphosphorylatable Y429A and Y429F mutants behaved the same as wild-type RhBG. Conversely, Y/A or Y/F but not Y/E or Y/D mutations of residue 429 abolished the exclusive basolateral localization of RhBG in polarized epithelial cells. All these results led to a model in which targeting and ammonium transport function of RhBG are regulated by both phosphorylation and membrane skeleton binding of the C-terminal cytoplasmic domain.

RhBG is a nonerythroid member of the Rhesus (Rh) protein family, mainly expressed in the kidney and belonging to the Amt/Mep/Rh superfamily of ammonium transporters. The epithelial expression of renal RhBG is restricted to the basolateral membrane of the connecting tubule and collecting duct cells. We report here that sorting and anchoring of RhBG to the basolateral plasma membrane require a cis-tyrosine-based signal and an association with ankyrin-G, respectively. First, we show by using a model of polarized epithelial Madin-Darby canine kidney cells that the targeting of transfected RhBG depends on a YED motif localized in the cytoplasmic C terminus of the protein. Second, we reveal by yeast two-hybrid analysis a direct interaction between an FLD determinant in the cytoplasmic C-terminal tail of RhBG and the third and fourth repeat domains of ankyrin-G. The biological relevance of this interaction is supported by two observations. (i) RhBG and ankyrin-G were colocalized in vivo in the basolateral domain of epithelial cells from the distal nephron by immunohistochemistry on kidney sections. (ii) The disruption of the FLD-binding motif impaired the membrane expression of RhBG leading to retention on cytoplasmic structures in transfected Madin-Darby canine kidney cells. Mutation of both targeting signal and ankyrin-G-binding site resulted in the same cell surface but nonpolarized expression pattern as observed for the protein mutated on the targeting signal alone, suggesting the existence of a close relationship between sorting and anchoring of RhBG to the basolateral domain of epithelial cells.

Background: The routine prenatal determination of fetal RhD blood group would be very useful in the management of pregnancies in RhD-negative women, as up to 40% of these pregnancies bear a RhD-negative fetus. The fetal DNA present in maternal plasma offers an opportunity for risk-free prenatal diagnosis., Aim: This study focused on the feasibility and accuracy of large-scale RhD fetal diagnosis in non-immunized and anti-D immunized RhD-negative women., Methods: Plasma DNA was extracted from 893 RhD-negative pregnant women and amplified in exons 7 and 10 of the RHD gene using conventional and real-time PCR. The results were then compared with the RHD fetal genotype determined on amniotic cells and/or the RhD phenotype of the red blood cells of the infants at birth., Results: After exclusion of 42 samples from women exhibiting a nonfunctional or rearranged RHD gene, fetal RhD status was predicted with a 99.5% accuracy. A strategy is also proposed to avoid the small number of false-positive and -negative results., Conclusion: Fetal RHD genotyping from maternal plasma DNA in different clinical situations may be used with confidence.

Case Reports: Three cases of an outbreak of familial foodborne botulism are reported. The food incriminated could not be identified despite a careful investigation into the food history of the patients. The outcome was good following endotracheal ventilation and botulism antitoxin trivalent therapy., Conclusion: In France, foodborne botulism is an uncommon public health disease, and with a good prognosis when the diagnosis is promptly performed. The value of emergency electromyographic findings is emphasized, particularly when the repetitive stimulation of the motor nerve shows a presynaptic block of neuromuscular transmission. Management depends on the symptomatology, and trivalent antitoxin therapy is the only specific treatment.

The neurogenic thoracic outlet syndrome includes the symptoms caused by the compression of the brachial plexus at some point between the interscalene triangle and the inferior border of the axilla. Five patients diagnosed as having neurogenic thoracic outlet syndrome were examined. We determinated clinical and electrophysiological features which lead to thoracic outlet syndrome diagnosis. The clinical features included paresthesia and pain along the inner part of the arm, forearm and hand. Diminished sensation was rare. Muscle weakness was usual and muscle atrophy was associated in severe cases. The association with a lower cervical rib was useful. Electrodiagnostic studies always showed abnormalities. Electromyographic studies showed a reduced recruitment pattern of motor unit activation in intrinsic hand muscles. The medial antebrachial cutaneous nerve action potential amplitude was low. Nerve conduction studies also showed loss of amplitude of the ulnar sensory and median motor responses.

The effects of a pure benzodiazepine antagonist (Flumazenil) on the responses R1 and R2 of the blink reflex, psychomotor tests, and Event Related Potentials (ERP), in six healthy volunteers sedated with Midazolam have been compared. Measurements were made during each of four successive phases. Phase 0 corresponded to control recordings. Midazolam was administered rapidly during phase 1 and slowly during phase 2. Phase 3 corresponded to spontaneous waking once the administration of Midazolam had been stopped. Flumazenil was administered during phase 2. As the subjects fell asleep, R1 and R2 were the last parameters to disappear. Under the influence of Flumazenil, R1 was the first to reappear, while R2 did not recur until complete waking, and the other tests were unpracticable. During phase 3, R1 reappeared before R2 once more, the psychomotor test responses and ERP returning only later. The modifications of both R1 and R2 of the blink reflex are a good criterion of the presence of BZD in a toxic coma and a good test to indicate the depth of a coma or a sedation with BZD, whilst ERP, since they require the cooperation of the patient, are a test of vigilance and not of awakening.

We studied the latency and amplitude of the P 300 wave of event-related potentials (P 3) in 19 hospitalised schizophrenic patients. We used an odd ball paradigm procedure in acoustic stimulation. We found a negative correlation between the amplitude of P 3 and negative schizophrenic symptomatology, measured by the negative BPRS score and the SANS score. However, no link would appear to exist in our study between positive symptomatology and P 3 amplitude. The correlation with the negative BPRS score is found in both evaluations, at the beginning and at the end of the period of hospitalisation. P 3 latency would appear to be independent of either positive or negative schizophrenic symptomatology. It would thus appear to us that the negative symptomatology, rather than the positive, could be at the origin of marked changes in P 3, observable fro relatively simple experimental but parameters such as reaction time or error scores remain to be specified, even if they appear to intervene infrequently. The use of event-related potentials would thus appear pertinent in clinical research and could help in the homogenisation of schizophrenic populations studied.

Far-field stationary potentials have been said to result from several factors such as changes in the anatomical orientation of the direction of a propagating nerve action potential (AP) or local modifications of the impedance in the external volume conductor by changes in its geometry or resistivity. In the case of an impedance variation due to the presence of boundaries in the geometry of the medium, the findings reported in this paper showed that it is possible to record simultaneously AP and stationary potentials which we have called boundary potentials (BPs). The BP amplitude depended on the number of active axons at the boundary, on the distance between the boundary and one of the recording electrodes, and on the local impedance variation. Its polarity depended only on the direction of the AP propagation relative to the sign of the local impedance modification, the recording electrodes being in the same relative positions with respect to the direction of the propagating impulse. Finally, the recording of a BP remained possible whatever the relative position of the boundary and of the recording electrodes. These findings are in accordance with some clinical observations not yet explained.

Unlabelled: This work was undertaken because there were only few reports on neurological aspects on lepromatous leprosy. We studied 30 patients suffering from lepromatous leprosy who, at their first visit to the Institute had never been treated. The clinical examination included a quantitative evaluation of the neurological status following the method developed by Pearson. Motor and sensory nerve conduction velocities were measured: values of conduction velocity and distal amplitude were analysed and compared to those of a group of 22 healthy subjects., In Conclusion: (a) There is a high frequency of clinical and especially electrophysiological neurological impairment. This impairment can be extremely precocious and may happen shortly after the first cutaneous signs. (b) Nervous impairment is diffuse, bilateral but not homogeneous. These are characteristics of mononeuritis multiplex. Impairement is predominantly sensitive and tactile sensibility is more involved than thermo-algic sensation. (c) The radial superficial nerve is the most frequently involved clinically and electrophysiologically. (d) The electrophysiological results, showing a normal or slightly reduced conduction velocity and a low amplitude of evoked potentiel are in favour of a predominantly axonal damage.

Increased free erythrocyte protoporphyrin concentrations and depressed motor nerve conduction velocities (MNCV) were observed in 45 patients on maintenance haemodialysis. Neither of these findings could be correlated with age, duration or frequency of dialysis, or the degree of uraemia present. A strong negative correlation (r=--0-53; P less than 0-001), however, existed between the free erythrocyte protoporphyrin level and the MNCV, which suggested either (a) a direct effect of iron status on nerve function, or (b) a toxic factor in "uraemia" that depresses both nerve conduction and haemsynthetase activity.

Seven children with early onset cholestasis who developed signs of peripheral neuropathy were investigated before and after one and a half to three years of treatment by vitamin E. This neuropathy appeared to be due to neuronoaxonal degeneration, but unusual Schwann cell inclusions were also observed. Although the treatment stabilized or improved the condition of all patients, no striking changes were noted neither in the EMG nor in the second nerve biopsy of a patient treated for three years. As the pathological process concerned it is probably both a developmental disorder and a degenerative phenomenon, substitutive vitamin E treatment should be proposed very early in life.

A prospective study into the aetiology of presumed primary non-obstructive cardiomyopathy was carried out in 57 patients who had no lesions of the trunk of the coronary artery; one case of haemochromatosis and one of amyloidosis were found. Excluding these two cases of cardiomyopathy which were in fact secondary, most of the others were associated with manifestations or with complications of myocardial diseases (two pulmonary emboli and one case of jaundice) or pathology associated with it. Investigation into possible infection, biochemical abnormalities and dietary indiscretion (alcohol, colza oil), were unfruitful. Electromyographic changes of the "myositic" type were very common. The bicycle ergometry test was often interrupted through fatiguing of the peripheral muscles. These findings suggest that the muscular abnormalities may not be limited to the heart. The cost of an enquiry of this type has been investigated.