Quantum Hall Valley Splitters and a Tunable Mach-Zehnder Interferometer in Graphene.

Graphene is a very promising test bed for the field of electron quantum optics. However, a fully tunable and coherent electronic beam splitter is still missing. We report the demonstration of electronic beam splitters in graphene that couple quantum Hall edge channels having opposite valley polarizations. The electronic transmission of our beam splitters can be tuned from zero to near unity. By independently setting the beam splitters at the two corners of a graphene p-n junction to intermediate transmissions, we realize a fully tunable electronic Mach-Zehnder interferometer. This tunability allows us to unambiguously identify the quantum interferences due to the Mach-Zehnder interferometer, and to study their dependence with the beam-splitter transmission and the interferometer bias voltage. The comparison with conventional semiconductor interferometers points toward universal processes driving the quantum decoherence in those two different 2D systems, with graphene being much more robust to their effect.

Scaling behavior of electron decoherence in a graphene Mach-Zehnder interferometer.

Over the past 20 years, many efforts have been made to understand and control decoherence in 2D electron systems. In particular, several types of electronic interferometers have been considered in GaAs heterostructures, in order to protect the interfering electrons from decoherence. Nevertheless, it is now understood that several intrinsic decoherence sources fundamentally limit more advanced quantum manipulations. Here, we show that graphene offers a unique possibility to reach a regime where the decoherence is frozen and to study unexplored regimes of electron interferometry. We probe the decoherence of electron channels in a graphene quantum Hall PN junction, forming a Mach-Zehnder interferometer1,2, and unveil a scaling behavior of decay of the interference visibility with the temperature scaled by the interferometer length. It exhibits a remarkable crossover from an exponential decay at higher temperature to an algebraic decay at lower temperature where almost no decoherence occurs, a regime previously unobserved in GaAs interferometers.

Dosing accuracy of artesunate and amodiaquine as treatment for falciparum malaria in Casamance, Senegal.

OBJECTIVES: Several products of artesunate plus amodiaquine (AS + AQ) are being deployed in malaria-endemic countries for treating uncomplicated falciparum malaria but dosing accuracy and consequential effects on efficacy and tolerability have not been examined. METHODS: Patients with parasitologically confirmed, uncomplicated falciparum malaria were treated and followed by research teams or local health centre staff in Casamance, Senegal. AS + AQ was given as: (i) loose combination (AS 50 mg, AQ 200 mg), dosed on body weight, or (ii) co-blistered product (AS 50 mg, AQ 153 mg) dosed by weight or age. Target doses were: (i) AS 4 (2-10) mg/kg/day and (ii) AQ 10 (7.5-15) mg/kg/day. Patients receiving therapeutic doses defined dosing accuracy. Treatment-emergent signs and symptoms (TESS) were recorded. RESULTS: A total of 3277 patients were treated with loose (n = 1972, weight-dosed) or co-blistered (n = 1305, 962 age-dosed, 343 weight-dosed) AS + AQ by the research team (n = 966) or clinic staff (n = 2311). AS was dosed correctly in >99% with all regimens. Loose AQ by weight was 98% correct. The co-blister AQ overdosed 18% of patients when dosed by age and underdosed 13% by weight. Low weight was an independent risk factor for overdosing. The co-blister had significantly more TESS than the loose product [117/1305 (9%) vs. 41/1972 (2%), relative risk = 4.3 (95% CI: 3.0-6.1, P < 0.0001)]. Age-based dosing accounted for the difference. TESS occurred mostly within one day (72%) and were mild or moderate (75%). CONCLUSION: Artesunate is easier to dose than AQ. Currently available age-dosed, co-blistered AS + AQ tends to overdose AQ and is less well tolerated than loose tablets. It is not the optimal presentation of AS + AQ.

Systematic review of utilities in abdominal aortic aneurysm.

INTRODUCTION: Two main treatments exist for the repair of abdominal aortic aneurysm (AAA). Open surgical repair has been the standard treatment, but more recently endovascular aneurysm repair (EVAR) has been introduced as a less invasive technique. To compare the long-term outcomes of these, utility outcomes have been suggested to be relevant. OBJECTIVE: To review studies comparing the utility outcomes of open repair and EVAR treatment for AAA. DESIGN: database search with strict inclusion and exclusion criteria. MATERIALS AND METHODS: The search was performed in PubMed and EMBASE covering terms relating to AAA and utility. Studies were analysed qualitatively. RESULTS: 10 studies of AAA met the review criteria. The comparative utility scores for the different treatments varied considerably between studies. A Canadian cohort study estimated EVAR as more favorable than open repair, while randomised controlled trials reported lower utilities with EVAR, except for one month post-surgery in the EVAR 1 trial. Furthermore, after screening for AAA, patients testing positive gave similar QoL-5D scores, but worse visual analogue scores than those testing negative. CONCLUSION: There were few studies calculating utilities in AAA, with inconsistent findings. The limited reporting of data prevents in-depth analysis to explain the differences.

Poisoning by Cnestis ferruginea in Casamance (Senegal): an etiological approach.

Since several years, in the area of Kabrousse in Casamance (Senegal), a neurotoxic syndrome has caused more than 50 human deaths. Field studies showed that epidemic could be due to consumption of leave decoction of Cnestis ferruginea, a tropical plant belonging to the Connaraceae family. An ethnobotanical study has been conducted in order to investigate the traditional uses of C. ferruginea, and describe the circumstances and the symptoms of this plant poisoning. As a first experimental approach, the leave decoction was tested for its ability to induce cytotoxic effects using the XTT method. A phytochemical approach revealed the presence of methionine sulfoximine (MSX), a neurotoxic amino acid, in the plant extract by gas chromatography-mass spectrometry (GC-MS). The description of this poisoning, the cytotoxic activity of the decoction and the occurence of MSX in leaves of C. ferruginea constituted the first etiological data on this poisoning.

[Tolerance of amodiaquine]. / Tolérance de l'amodiaquine.

Amodiaquin is still considered as a poorly tolerated antimalarial causing hematological and hepatic toxicity. In view of complications observed during prophylaxis, the WHO has advised against the use of amodiaquin for prophylaxis as well as treatment. However due to the rapid increase in chloroquine resistance and to the absence of reported cases of toxicity during treatment, the WHO has reconsidered its position and now accepts therapeutic use of amodiaquin under some conditions. It has been demonstrated that amodiaquin activates release of quinoneimine granulocytes causing hematological toxicity. In liver microsomes, metabolism into desethyl derivatives is catalyzed by cytochrome P450 CYP2C8 that has several variant forms with low activity on amodiaquin clearance. Carriers of these variants are at a higher risk for adverse effects. Currently the safety and effectiveness of amodiaquin in association with artesunate has been documented and this therapeutic combination is now recommended for first line treatment of uncomplicated Plasmodium falciparum malaria in 18 African countries.

[Treatment of pediatric malaria in Africa: act at issue]. / Traitement du paludisme de l'enfant en Afrique: les act en question.

Artemisinin-based combination therapies (ACT) have been proposed as alternatives to currently used antimalarials and are poised large-scale deployment in Africa. These combinations are particularly attractive for managing malaria in children. Expected benefits of ACT include enhanced efficacy, rapid action, stabilized antimalarial resistance growth and lower malaria transmission. This article discusses what can be reasonably expected of ACT in an African setting with emphasis on patient comfort.

[Malignant peripheral nerve sheath tumor in the posterior mediastinum]. / Tumeur maligne de la gaine d'un nerf périphérique: une lésion rare du médiastin postérieur.

We report the case of a 52-year-old male patient who developed a malignant peripheral nerve sheath tumor (MPNST) localized in the posterior mediastinum. The diagnosis of this rare tumor is difficult because the clinical presentation of the benign or malignant types is often similar, i.e. elective pain and bone erosions. Similarly, radiological procedures do not always allow distinction between the two types. MNR and CT-scan are the first line procedures: they localize and characterize the lesions, and CT-scan can also be a guide for biopsies. Histological diagnosis is required, but diagnosis can be compromised by the heterogeneous nature of the tumor. Surgical treatment should be undertaken whenever possible. Survival was unusually long in our patient, more than 5 years after discovery of the MPNST. This type of sarcoma is often very aggressive with frequent development of local recurrences and metastases.

High-output right ventricular failure secondary to hepatic arteriovenous microfistulae. Selective arterial embolization treatment.

A patient with diffuse hepatic arteriovenous microfistulae suffered from secondary high-output right ventricular failure, pulmonary hypertension, and ascites, all of which could be managed by selective embolization of the hepatic artery. The vascular lesion of the liver seems to be essential, although hemorrhagic hereditary telangiectasia , perhaps aggravated by administration of oral contraceptives, may be considered contributory factors in this case.

[Port-site metastasis following laparoscopic radical prostatectomy for mucinous adenocarcinoma of the prostate]. / Métastase orificielle après prostatectomie radicale coelioscopique pour un adénocarcinome mucineux de la prostate.

A 52-year-old man underwent laparoscopic radical prostatectomy for mucinous adenocarcinoma. Eight months later, an abdominal wall metastasis developed at the trocar site through which the laparoscope had been introduced. To our knowledge, it is the first reported case of port site metastasis after laparoscopic radical prostatectomy.

[In vitro evaluation of the sensitivity of Plasmodium falciparum to chloroquine using the deli-microtest in region of Dakar, Senegal]. / Evaluation de la sensibilité in vitro de Plasmodium falciparum à la chloroquine par le DELI-microtest dans la région de Dakar (Senegal).

This study was carried out between 2000 and 2001 in the peri-urban Pikine area located 15 km from Dakar, Senegal. The purpose was to evaluate the in vitro sensitivity of Plasmodium falciparum isolates to chloroquine, which was the recommended first-line drug for uncomplicated malaria treatment in Senegal. Testing was carried out using the double-site enzyme-linked lactate dehydrogenase imnunosorbent (DELI) microtest. The DELI-microtest is an ELISA method using 2 monoclonal antibodies against 2 antigenic sites of the specific P. falciparum lactate dehydrogenase (LDH) enzyme. The level of LDH is proportional to the extent of parasite growth. P. falciparum isolates were cultured in 96-well plates in RPMI 1640 medium supplemented with hypoxanthine and albumax, in the presence of chloroquine sulphate concentrations ranging from 5.6 nM/L to 2870.8 nM/L. Plates were incubated in a candle-jar for 48 hours at 37 degrees C and frozen at -20 degrees C. The DELI-microtest was performed using the supernatant of hemolysed cultures. The amount of pLDH released was evaluated based on optical density. The chloroquine sensitivity of the isolate was estimated based on IC50 with a cut-off of <100 nM/L. Geometric mean IC50 values were 41 nM/L (range: 4.8 nM/L to 1435 nM/L) and 135 nM/L (range: 8.63 nM/L to 2153 nM/L) in 2000 and 2001 respectively. This study demonstrated a dramatic increase in the in vitro resistance of P. falciparum to chloroquine from 30% in 2000 to 59.6% in 2001. These findings suggest that regular surveillance of in vitro drug resistance is important to predict in vivo drug resistance and allow timely changes in public health recommendations.

[Changes in malaria prevalence and management of fevers from 2000 to 2012 in Casamance, Senegal]. / Évolution de la prévalence du paludisme et de la prise en charge des fièvres de 2000 et 2012 en Casamance, Sénégal.

Before 2006 in Senegal, in the absence of clinical diagnosis, all fever cases were considered as malaria and treated with chloroquine. Between 2004-2006, to face the dramatic increase of Plasmodium falciparum resistance to chloroquine, the combination of amodiaquine plus sulfadoxine-pyriméthamine was recommended for treatment. In 2006, rapid diagnostic tests were introduced and the treatment with a combination of artesunate plus amodiaquine (ASAQ) became the national recommendation for malaria treatment in 2007. This coincided with a decrease of the prevalence of malaria cases and change in fever management. Since 1995 in Mlomp in Casamance, thin and thick blood smear examination has systematically been done in patients with fever and clinical signs of malaria, and treatment with ASAQ given as experimental procedure. Between 2000 and 2012, 70,892 outpatients were attending the health center, and 51.2% of them for fever. Among these fever cases, 72.4% were suspected of malaria and 27.6% were identified as bacterial and viral infections. Confirmed malaria cases decreased dramatically from 1365 in 2000 to 53 in 2012. While comparing the 2 periods 2000-2006 and 2007-2012, the number of fever cases decreased by half, the number of fever identified as non malaria doubled and malaria treatment given decreased by 86%. Improvement of fever management in Mlomp has contributed to a better identification of their cause and to a decrease of inappropriate malaria treatments.

[Gametocyte carriage in asymptomatic Plasmodium falciparum infections in Haiti (2010-2013)]. / Portage de gamétocytes de Plasmodium falciparum en Haïti en 2010-2013.

A survey conducted from May 2010 to October 2013 in five from ten departments of Haiti among 5,342 persons aged from 1 to 107 years showed a gametocytic rate = 3.2%. However, it varies greatly from one Department to another, ranging from 0.5% in Grande Anse Department to 5.9% in Southeast Department. Malaria is present in Haiti in heterogeneous coastal foci. Gametocytes occur at all ages, but two times most often in male under 20 years. Entomological studies in Haiti are needed to better characterize the relationships between man and the vector Anopheles albimanus, adapting the fight more effectively.

Taenia crassiceps invasive cysticercosis: a new human pathogen in acquired immunodeficiency syndrome?

A fluctuant, painful, subcutaneous, and intermuscular tumor developed in a 38-year-old man with severe acquired immunodeficiency syndrome (AIDS) in which immunodeficiency was severe. Surgery revealed lesions that formed a multilocular pouch embedded in deep tissues in the forearm filled with tapiocalike material containing a viscous fluid, granules, and cysticercilike small vesicles. Pathologic and parasitologic evaluation showed cysticerci embedded in a fibrocollagen reaction with inflammatory granulomatous reaction. Each cysticercus contained an invaginated scolex with two rows of small (i.e., 80 microm) and large (i.e., 114 microm) rostellar hooks, identical to larva of Taenia crassiceps. All clinical, parasitologic, and pathologic features of these cysticerci were very different from those of all other larval cestode (i.e., Taenia solium cysticercosis, coenurosis, sparganosis, cysticercosis due to Taenia saginata [Cysticercus bovis], primary and secondary hydatidosis [Echinococcus species]). T crassiceps cysticerci usually develop in subcutis and pleuroperitoneal cavities of rodents, whereas the adult tapeworm is commonly found in the digestive tract of foxes. Biologic properties of T crassiceps cysticerci and epidemiologic characteristics of pandemic human immunodeficiency virus (HIV) could eventually indicate new potential cases of T crassiceps cysticercosis in humans.

Emission tomography for assessment of diffuse alcoholic liver disease.

A method of quantitative liver tomoscintigraphy (SPECT) was compared for accuracy with planar scintigraphy (PS) in a group of patients with diffuse alcoholic liver disease. SPECT sensitivity was also compared with that of transmission computed tomography (CT), US, aminopyrine breath test (ABT) and liver chemistries (LC). One hundred and fourteen alcoholic patients with proven liver disease and 17 patients free of liver disease were included. Seven quantitative scintigraphic features and a score, including all criteria were considered. With a specificity of 95%, the sensitivity was 79% in steatosis and 97% in cirrhosis. SPECT showed a better sensitivity than PS (SPECT 89%, PS 66%), especially in patients with steatosis. In the same subsets of patients, SPECT sensitivity also compared favorably with that of transmission CT (SPECT 92%, CT 65%), ultrasonography (SPECT 88%, US 53%) and ABT (SPECT 90%, ABT 63%).

A cytopathic effect of Trichomonas vaginalis probably mediated by a mannose/N-acetyl-glucosamine binding lectin.

The pathogenic effect of a highly pathogenic strain of Trichomonas vaginalis on McCoy cell monolayers was investigated. Specific inhibition of the cytopathic effect by monosaccharides, such as N-acetyl-glucosamine (GlcNAc) and mannose (Man), was observed. Our preliminary results suggest that the pathogenicity of T. vaginalis depends on a lectin specifically sensitive to GlcNAc and to a lesser extent to Man. Although N-acetyl-mannosamine was found to be the most efficient inhibitor, this effect seems to be unrelated to the natural biological behaviour of the infested host.

Enzyme immunoassay detection of Cryptosporidium parvum inhibition by sinefungin in sporozoite infected HCT-8 enterocytic cells.

Complete parasite development was obtained in differentiated human enterocytic HCT-8 cells infected at confluence with Cryptosporidium parvum sporozoites, and evaluated in a quantitative enzyme immunoassay. Forty-eight hours after infection, a linear correlation was found between optical density values and the number of parasites determined in an immunofluorescent assay. Sinefungin exerted an inhibitory effect when added within 4 h after sporozoite addition to HCT-8 cultures (MIC50 = 38 mumol L-1), while the inhibitory effects of paromomycin and pentamidine dimethanesulfonate were also easily detected (MIC50 = 0.87 mumol L-1 and 0.27 mumol L-1, respectively). Except for high pentamidine dimethanesulfonate concentrations, no alteration in optical microscopy morphology or trypan blue exclusion of HCT-8 cells was observed in the presence of anticryptosporidial agents, which suggests that they were primarily active against developing parasites. Data suggest that EIA detection of C. parvum development in sporozoite-infected HCT-8 cells provides an accurate and convenient model for in vitro evaluation of parasite infectivity, growth and response to anticryptosporidial agents.

Biliary tract cryptosporidiosis immunosuppressed rat model.

Rats immunosuppressed by hydrocortisone acetate and a low protein diet were challenged with Cryptosporidium Parvum oocysts and studied on days 10, 35 and 70 post-infection. The biliary tract was found to be a major site of parasite infection. C. parvum was visible in the biliary papillary area in association with a proliferation of highly convoluted tubular glands. The papillary lumen was narrowed, and an upstream dilation with bacterial proliferation was seen. The liver was initially free of lesions, and subsequently exhibited late lesions of cholestasis. Parasites were not found in the pancreatic duct, although pancreatitis was frequently observed. Oocysts were consistently present in the distal portion of the ileum. Both challenged and unchallenged immunosuppressed rats, exhibited widespread focal hepatic infarcts and pyelonephritis. Other organs appeared free of lesions. In addition to the intestine, data identified the biliary tract as a major site of C. parvum infection and as a potential protected reservoir which may sustain a chronic infection.

Hydrogen peroxide gas plasma sterilization is effective against Cryptosporidium parvum oocysts.

The aim of this work was to evaluate in an immunosuppressed rat cryptosporidiosis model a new method that combines vacuum and low-temperature hydrogen peroxide gas plasma for sterilization of endoscopic material contaminated by Cryptosporidium parvum. Rats were challenged with oocysts either air-dried or air-dried and treated with vacuum alone or associated with gas plasma. No rat was found infected after gas plasma exposure of oocysts, whereas vacuum or air-drying alone resulted only in a decreased infectivity.