[Acquired ichthyosis and livedoid palmoplantar keratoderma: two unusual skin manifestations of systemic lupus erythematosus]. / Ichtyose acquise et hyperkératose livédoïde palmoplantaire: deux manifestations cutanées initiales atypiques de lupus systémique.

Acquired ichthyosis and livedoid palmoplantar keratoderma have rarely been described in systemic lupus erythematosus (SLE). In the first case, a 51-year-old man presented with generalized acquired ichthyosis associated with renal glomurelosclerosis and neurolupus. rituximab allowed total resolution of the acquired ichthyosis. A livedoid palmoplantar keratoderma was observed in a 45-year-old woman as the initial clinical manifestation of a systemic lupus erythematosus associated with Raynaud's phenomenon, photosensitivity and inflammatory polyarthralgia. Although the pathophysiology is not well-defined, these unusual cutaneous manifestations should be considered by physicians when diagnosis of SLE is suspected.

[Giant abdomino-pubic melanoma. A case report]. / Mélanome géant abdomino-pubien. À propos d'une observation clinique.

Cutaneous melanoma patients are usually young adults. The evolution into a nodular form darkens the prognosis because it increases the risk of metastasis occurrence. The only curative treatment is wide surgical excision when extension check is negative. We report a case of abdomino-pubic melanoma original by its amazing size, its spreading, both superficial and nodular, without metastasis, and its late occurrence to a senior patient. Curative management was performed with a plastic surgery technique: the abdominal plasty. The melanoma was removed with free margins and the patient was free of disease at six month. This report illustrates the interest of plastic surgery techniques in oncology. It also confirms that plastic surgeon forms an integral part of a multidisciplinary team managing patients with cutaneous melanoma.

Inhibition of the I(h) current in isolated peripheral nerve: a novel mode of peripheral antinociception?

Although the alpha2-adrenergic agonist clonidine has been shown to promote peripheral antinociception, its mechanism of action has not yet been clearly elucidated. By the use of the sucrose-gap method, we have shown that in C fibers of the rabbit vagus nerve, clonidine at micromolar concentrations enhances activity-dependent hyperpolarizations generated by the Na+-K+ pump during and after repetitive stimulation. Similar results were obtained with 10 microM of ZD 7288, a specific blocker of the hyperpolarization-activated cation current (I(h)) and with 2 mM of Ba2+ that blocks the inwardly rectifying potassium current (I(KIR)). Furthermore, clonidine had no added effect on the ZD 7288-induced response, whereas it produced a marked enhancement of Ba2+induced response. From these results, it can be concluded that clonidine enhances activity-dependent hyperpolarization by inhibiting the current I(h). We propose that clonidine, by increasing the threshold for initiating the action potential, induces a slowing or block of conduction and that this mechanism is the origin of the clonidine-induced antinociception. Finally, this study suggests a novel role for inwardly rectifying hyperpolarization-activated conductances in peripherally mediated antinociception.

Expression of beta subunit modulates surface potential sensing by calcium channels.

We have expressed the alpha 1 A calcium channel subunit alone, and in combination with different beta subunits, and investigated the effect of the external Ba2+ concentration on the voltage dependence of activation. Increasing the external Ba2+ concentration from 2.5 to 40 mM induced in all cases a depolarising shift of the potential for half-activation. The magnitude of this shift however, was different depending on whether the alpha 1 A subunit was expressed alone or with a beta subunit. Consistently, calculated external surface-charge density and potential were larger when a beta subunit was expressed. These results suggest that expression of an auxiliary subunit can influence calcium channel gating by modifying the sensitivity of the voltage sensor to the membrane potential profile.

Characterisation of alpha 1A Ba2+, Sr2+ and Ca2+ currents recorded with the ancillary beta 1-4 subunits.

Xenopus oocytes have been injected with different combinations of expression plasmids carrying the rat brain alpha 1A and different beta (beta 1-4) Ca2+ channel subunit cDNAs. Whole-cell Ba2+ and Ca2+ currents were recorded up to seven days after injection. Intra-oocyte injection of BAPTA allowed us to record uncontaminated Ba2+, Sr2+ currents. The alpha 1A calcium channel showed relative current amplitudes according to the sequence: IBa2+ > ISr2+ > ICa2+. The ratio ICa2+/IBa2+ was significantly larger when compared to the class C L-type Ca2+ channel (alpha 1C). However, currents flowing through alpha 1A and alpha (1C) subunits saturate for similar Ba2+ concentrations and display the anomalous mole fraction effect in the presence of mixtures of Ba2+ and Ca2+ ions in the external medium. In oocytes expressing the alpha 1A Ca2+ channel subunit, switching from extracellular Ba2+ to Ca2+ also induced a depolarising shift of current-to-voltage relation and the steady-state inactivation curve, and increased the time-to-peak of the current. Inactivation kinetics were poorly affected. Changes in gating and voltage-dependence of activation, but not in the voltage-dependent inactivation, were independent from the coexpressed beta subunit (except with the beta 4 subunit). Our data constitute strong evidence for the existence of differences in intra-pore Ca2+ binding sites between the alpha 1C and alpha 1A subunits, and emphasise the influence of the charge carrier on the modulation of alpha 1A properties by the beta subunits.