Single-Quantum-Dot Heat Valve.

We demonstrate gate control of electronic heat flow in a thermally biased single-quantum-dot junction. Electron temperature maps taken in the immediate vicinity of the junction, as a function of the gate and bias voltages applied to the device, reveal clearly defined Coulomb diamond patterns that indicate a maximum heat transfer at the charge degeneracy point. The nontrivial bias and gate dependence of this heat valve results from the quantum nature of the dot at the heart of device and its strong coupling to leads.

Thermal Conductance of a Single-Electron Transistor.

We report on combined measurements of heat and charge transport through a single-electron transistor. The device acts as a heat switch actuated by the voltage applied on the gate. The Wiedemann-Franz law for the ratio of heat and charge conductances is found to be systematically violated away from the charge degeneracy points. The observed deviation agrees well with the theoretical expectation. With a large temperature drop between the source and drain, the heat current away from degeneracy deviates from the standard quadratic dependence in the two temperatures.

Charge Puddles in Graphene near the Dirac Point.

The charge carrier density in graphene on a dielectric substrate such as SiO_{2} displays inhomogeneities, the so-called charge puddles. Because of the linear dispersion relation in monolayer graphene, the puddles are predicted to grow near charge neutrality, a markedly distinct property from conventional two-dimensional electron gases. By performing scanning tunneling microscopy and spectroscopy on a mesoscopic graphene device, we directly observe the puddles' growth, both in spatial extent and in amplitude, as the Fermi level approaches the Dirac point. Self-consistent screening theory provides a unified description of both the macroscopic transport properties and the microscopically observed charge disorder.

Single Quantum Level Electron Turnstile.

We report on the realization of a single-electron source, where current is transported through a single-level quantum dot (Q) tunnel coupled to two superconducting leads (S). When driven with an ac gate voltage, the experiment demonstrates electron turnstile operation. Compared to the more conventional superconductor-normal-metal-superconductor turnstile, our superconductor-quantum-dot-superconductor device presents a number of novel properties, including higher immunity to the unavoidable presence of nonequilibrium quasiparticles in superconducting leads. Moreover, we demonstrate its ability to deliver electrons with a very narrow energy distribution.

Reversibility of superconducting nb weak links driven by the proximity effect in a quantum interference device.

We demonstrate the role of the proximity effect in the thermal hysteresis of superconducting constrictions. From the analysis of successive thermal instabilities in the transport characteristics of micron-size superconducting quantum interference devices with a well-controlled geometry, we obtain a complete picture of the different thermal regimes. These determine whether or not the junctions are hysteretic. Below the superconductor critical temperature, the critical current switches from a classical weak-link behavior to one driven by the proximity effect. The associated small amplitude of the critical current makes it robust with respect to the heat generation by phase slips, leading to a nonhysteretic behavior.

Niobium-based superconducting nano-device fabrication using all-metal suspended masks.

We report a novel method for the fabrication of superconducting nano-devices based on niobium. The well-known difficulties of lithographic patterning of high-quality niobium are overcome by replacing the usual organic resist mask by a metallic one. The quality of the fabrication procedure is demonstrated by the realization and characterization of long and narrow superconducting lines and niobium-gold-niobium proximity SQUIDs.

Noise correlations in three-terminal diffusive superconductor-normal-metal-superconductor nanostructures.

We present measurements of current noise and cross correlations in three-terminal superconductor-normal-metal-superconductor (S-N-S) nanostructures that are potential solid-state entanglers thanks to Andreev reflections at the N-S interfaces. The noise-correlation measurements spanned from the regime where electron-electron interactions are relevant to the regime of incoherent multiple Andreev reflection. In the latter regime, negative cross correlations are observed in samples with closely spaced junctions.

Electron and phonon cooling in a superconductor-normal-metal-superconductor tunnel junction.

We present evidence for the cooling of normal-metal phonons, in addition to the well-known electron cooling, by electron tunneling in a superconductor-normal-metal-superconductor tunnel junction. The normal-metal electron temperature is extracted by comparing the device current-voltage characteristics to the theoretical prediction. We use a quantitative model for the heat transfer that includes the electron-phonon coupling in the normal metal and the Kapitza resistance between the substrate and the metal. It gives a very good fit to the data and enables us to extract an effective phonon temperature in the normal metal.

Influence of age on characteristics of polymyositis and dermatomyositis in adults.

In a retrospective study of 79 consecutive patients, we evaluated characteristics of polymyositis (PM) and dermatomyositis (DM) and compared clinical presentation, biochemical findings, histologic changes, evolution, complications, and mortality rate of elderly patients (aged > or = 65 yr) and younger patients (aged < or = 64 yr) at the onset of PM/DM. We found a high prevalence of PM/DM in elderly patients: 23 patients (29%) were aged 65 years or over. We also found that esophageal involvement (34.8% versus 16.1%, respectively) and bacterial pneumonia related to both ventilatory insufficiency and esophageal impairment (21.7% versus 5.4%, respectively) were more common in elderly patients compared with younger patients, resulting in increased morbidity and mortality rates. Moreover, malignancy frequency was higher in elderly patients compared with younger patients (47.8% versus 9.1%, respectively, p = 0.0001), particularly patients with DM (10/11). Fifty percent of malignancies were colon malignancies in elderly patients. Erythrocyte sedimentation rate, C-reactive protein, fibrinogen, and ferritin levels were also higher in the elderly patient group compared with the younger group, and the presence of serum hypoprotidemia, hypoalbuminemia, and anemia was more frequent. Finally, PM/DM complete remission was less frequent (13.6% versus 41.1%) and the mortality rate (47.8% versus 7.3%) was higher in elderly patients than in younger patients. The main causes of death in elderly patients were bacterial pneumonia, due to ventilatory insufficiency and esophageal impairment, and malignancies. Our findings therefore indicate that PM/DM-related esophageal and lung involvement should be systematically searched for in elderly patients. Esophageal manometry and pulmonary function tests should become an integral part of initial evaluation in elderly patients for early detection of impairment. Moreover, as we observed a marked overrepresentation of colon cancer in elderly patients with DM, we suggest that the search for malignancies in elderly patients with DM should include lower gastrointestinal tract investigations.

Localization and solubilization of hyaluronan and of the hyaluronan-binding protein hyaluronectin in human normal and arteriosclerotic arterial walls.

Hyaluronectin (HN), a hyaluronan (hyaluronic acid, HA)-binding glycoprotein isolated from human brain, was studied in normal and atherosclerotic human arteries. It can be detected and assayed in tissue samples by immunohistochemistry. In addition, its high and specific affinity for HA makes it possible to develop specific histological localization of HA using HN as a probe. We tested the presence of HN and HA in human carotid artery samples from adults and newborns. In atheroma-free arterial samples HN was found in the intima, between smooth muscle cells and in the adventitial extracellular matrix. In atherosclerotic lesions, HN was strongly expressed in the diffuse thickened intima and surrounding extracellular microcrystalline calcium deposits, and very little in the lipid core. HA was found in the same locations. The similar localizations of HN and HA shown by immunohistology and demonstration of HN-HA complexes by high pressure liquid chromatography (HPLC) suggest that they are associated in vivo.

An uncommon association: celiac disease and dermatomyositis in adults.

We describe the case of a patient with a two-year history of adult dermatomyositis (DM) who developed malabsorption revealing celiac disease. Our observation raises the question of an association between DM and celiac disease as part of a continuum, suggesting that celiac disease may be included within the spectrum of the gastrointestinal manifestations of DM and polymyositis (PM). From a practical point of view, our data indicate that the diagnosis of celiac disease should be suspected in PM/DM patients exhibiting malabsorption syndrome. Based on our findings, we further emphasize that an evaluation for celiac disease, including anti-gliadin antibodies, anti-endomysium antibody and tissue trans-glutaminase antibodies should be considered in PM/DM patients presenting with unusual and unexplained gastrointestinal features. This could lead to the early management of such patients, resulting in decreased morbidity (i.e., malnutrition and malignancy) related to misdiagnosed celiac disease.

Endothelins. A potential target for pharmacological intervention in diseases of the elderly.

The existence of vasoconstrictive factors originating from the endothelium was confirmed by the description of endothelin, a 21-amino-acid peptide derived from a series of precursors, preproendothelin and a 38-amino-acid big endothelin. Three isoforms of endothelin, endothelin-1, -2 and -3, and 3 receptors (ETA, ETB and ETC) have been described and cloned. The cellular mode of action of endothelin seems to involve the modulation of intracellular calcium (through inositol trisphosphate, diacylglycerol and phospholipase C) and activation of calcium channels. The effects of endothelin are predominantly on the cardiovascular system. Its major effect is vasoconstriction, both systemic and pulmonary, with additional positive chronotropic and inotropic effects on the heart. It has also been implicated in homeostatic regulation of kidney microcirculation, and has powerful mitogenic effects on fibroblasts and smooth muscle cells. Many additional effects have been described on the endocrine system and on other systems. However, the clinical relevance of such effects is uncertain. Increased plasma endothelin levels have been reported in many diseases, but as yet it is not certain whether they are a cause or a consequence of the pathology. Pathologies most probably related to endothelin dysfunction are the vasospastic diseases, especially vasospasm after subarachnoid haemorrhage. Endothelin could be implicated to a lesser measure in diseases typical of the elderly population, such as hypertension or atherosclerosis. Drugs are being developed which act on endothelin metabolism, the most promising of which appear to be the inhibitors of endothelin converting enzyme and endothelin receptor antagonists. Some already existing drugs, such as calcium channel blockers or angiotensin converting enzyme inhibitors, probably act at least in part by interfering with endothelin metabolism or effects.

[Cryptococcus neoformans meningitis and cirrhosis. Value of fluconazole]. / Méningite à Cryptococcus neoformans et cirrhose. Intérêt du fluconazole.

We report the case of a 80-old-year woman with cryptococcal meningitis and cirrhosis. The diagnosis of this rare infectious complication is probably underestimated in patients with cirrhosis. Of diagnostic value is the detection of cryptococcal antigen in cerebral fluid. Fluconazole could improve an otherwise poor prognostic.

[Idiopathic hypereosinophilic syndrome with predominant digestive manifestations or eosinophilic gastroenteritis? Apropos of 2 cases]. / Syndrome hyperéosinophilique idiopathique à manifestations digestives prédominantes ou gastroentérite à éosinophiles? A propos de deux observations.

We report two cases of hypereosinophilic syndrome with predominant gastrointestinal signs, which could have been mistaken for eosinophilic gastroenteritis. In the first case, the patient presented with eosinophilic ascites; documentation of pulmonary involvement allowed to easily establish the diagnosis. In the second case, the patient presented with diarrhea and malabsorption; gastrointestinal and pancreatic involvement seemed isolated. Cases reported as eosinophilic gastroenteritis in the literature with polyvisceral involvement raise the possibility of hypereosinophilic syndrome. We suggest that diffuse eosinophilic gastroenteritis could in fact be an isolated manifestation of the idiopathic hypereosinophilic syndrome.

[Hormone replacement therapy in menopause, hemostasis and thromboembolic risk]. / Hormonothérapie substitutive de la ménopause, hémostase et risque thrombo-embolique.

The association between oral contraceptives and the risk of thrombosis is now well documented. Conversely, post-menopausal hormonal therapy with doses and types of estrogen vastly different, seems not conducive of venous thromboembolism. Clotting factor abnormalities which have occasionally been observed in patients receiving hormone replacement therapy appear to be relatively unimportant clinically. Since no study is available on the assessment of the risk of thrombosis with these treatment, any hormone replacement therapy should be contraindicated as a principle, in both patients with recurrent venous thrombosis with or without known hemostatic abnormality. This attitude could be modified, if the therapy is justified by osteopenia or clinical complaints, after consulting specialist in gynecology, endocrinology, angiology or rheumatology, informed of the risk arising from such hormonal therapies. In theses particular cases, hormonal therapy with the fewest metabolic effects could be used.

[Erythermalgia and systemic lupus erythematosus]. / Erythermalgie et lupus erythémateux disséminé.

We report three cases of erythermalgia associated with systemic lupus erythematosus corresponding to different clinical situations in such an association. The first patient developed erythermalgia during the course of systemic lupus erythematosus. In the second, erythermalgia preceded other symptoms of systemic lupus erythematosus by four years. In the third, erythromelalgia was not related to a flare-up of systemic lupus erythematosus, but to thrombocythemia, a complication of immunosuppressive therapy. These cases permit a discussion on terminology and classification of erythromelalgia and erythermalgia. However, more than terminology or classification into three types or into adult-onset and early-onset (childhood) erythromelalgia, the important is to consider primary and secondary forms. We used a classification into two types: primary (or erythermalgia) with subdivision into sporadic and familial subtypes, and secondary with subdivision into erythermalgia related to myeloproliferative disorders and erythermalgia related to other diseases, such as systemic lupus erythematosus, or to drugs (erythermalgia-like syndrome).

[Vasoactive factors of endothelial origin]. / Les facteurs vasoactifs d'origine endothéliale.

The discovery of powerful vasoactive compounds synthetized by the vascular endothelium has led to the elaboration of new physiopathological concepts. We review the present state of knowledge about the role, potential therapeutic virtues, and physiopathological consequences of the three major endothelial vasoactive factors: 1. Prostacyclin (PG12), a powerful vasodilator, and the most potent known inhibitor of platelet aggregation, derived from arachidonic acid metabolism: 2: Endothelium-derived relaxing factor (EDRF) a powerful vasodilator thought to be a short-acting nitroxide; 3: Endothelin, a 21 amino-acid peptide with potent vasoconstricting properties.

[The vascular risk of third generation contraceptive pills]. / Risque vasculaire des pilules contraceptives de troisième génération.

The new progestative molecules have allowed the reduction of the doses of steroids in estroprogestative pills. They have a reduced androgenic activity allowing the positive effects of ethinylestradiol on lipid metabolism with decreased myocardial infarct, ischemic or hemorrhagic stroke. However it is necessary to consider the woman's entire risk factor profile when prescribing oral contraceptives. Unfortunately, combined estroprogestatives containing low-dose estrogen and the progestagens desogestrel or gestodene are associated with an increased risk for nonfatal venous thromboembolic disease. The occurrence of venous thromboembolic disease in a woman with oral contraceptive requires to search for a hereditary abnormality especially a resistance to the anticoagulant effect of activated protein C. Conversely it seems necessary to screen for the factor V Leiden mutation in women starting oral contraceptives who have a history of a familial venous thrombosis story.

[Childhood acromelalgia a propos of a case revealing Fabry's disease]. / Acromélalgies de l'enfant a propos d'une observation révélatrice de maladie de Fabry.

The occurrence of an acrosyndrome (Raynaud's phenomenon, erythermalgia, acrodynia...) in childhood may be the first manifestation of a general disease. Though it can be an early onset Raynaud's disease, it could also be the first sign of a connective tissue disease (juvenile polyarthritis, mixed connectivitis...) or of a overload disorder. We report a case of childhood-onset acromelalgia leading to the discovery of Fabry's disease. This chromosome X-linked hereditary disorder, resulting in the ubiquitous accumulation of neutral sphingolipids, is usually rapidly suspected by the finding of "boxer-short" angiokeratoma. Diagnosis is confirmed by the ophthalmic examination (cornea verticillata), by the pathological examination of a skin sample, and by the measure of alpha-galactosidase A activity. Treatment is usually only symptomatic, but the discovery of the mutations responsible for the disease could open the way to specific therapy.

[Horton's disease with involvement of the arterial trunks of the arms. Pathogenic role of anticardiolipin antibodies? Report of two cases]. / Maladie de Horton avec atteinte des troncs artériels des membres supérieurs. Rôle pathogène des anticorps anticardiolipine? A propos de deux observations.

Diffuse arterial involvement in temporal arteritis is well known but the intimate mechanisms of vasculopathy is unknown. Recently the presence of anticardiolipin antibodies (aCL) has been recognized in giant cell arteritis. We report two cases of temporal arteritis with diffuse arterial involvement associated with aCL (axillary arteries in the two cases associated with femoral arteries in one). During corticosteroid and anticoagulant therapy, a rapid improvement was noted with regression of upper-limb ischemia. One month later, the aCL were absent. These cases confirm the presence of aCL in giant cell arteritis with diffuse arterial involvement. These antibodies might imply severe vascular damage and could play a role in pathogenesis of the vasculopathy of temporal arteritis. Their presence suggests the necessity of anticoagulant therapy at the beginning of corticosteroid therapy.