Temperature-dependent transport properties of CVD-fabricated n-GaN nanorods/p-Si heterojunction devices.

We report on the structural, electrical, and transport properties of high quality CVD-fabricated n-GaN nanorods (NRs)/p-Si heterojunction diodes. The X-ray diffraction (XRD) studies reveal the growth of hexagonal wurtzite GaN structure. The current-voltage (I-V) characteristics of the n-GaN NRs/p-Si heterojunction were measured in the temperature range of 300-475 K. The ideality factor (n) and zero-bias barrier height (ϕ B0) are found to be strongly temperature-dependent. The calculated values of ϕ B0 are 0.95 and 0.99 eV according to Gaussian distributions (GD) and modified Richardson for GD, respectively, which are in good agreement with the band offset of GaN/Si (0.95 eV). A Richardson constant of 37 cm-2 K-2 was obtained from the modified Richardson plot, which is close to the theoretical value for p-Si (32 cm-2 K-2). The Gaussian distributions (GD) of inhomogeneous barrier height (BHs) and modified Richardson for GD of BHs with TE have also been used to explain the obtained transport properties.

Inferring the population structure of the Maghreb sheep breeds using a medium-density SNP chip.

North Africa has a great diversity of indigenous sheep breeds whose origin is linked to its environmental characteristics and to certain historical events that took place in the region. To date, few genome-wide studies have been conducted to investigate the population structure of North African indigenous sheep. The objective of the present study was to provide a detailed assessment of the genetic structure and admixture patterns of six Maghreb sheep populations using the Illumina 50K Ovine BeadChip and comparisons with 22 global populations of sheep and mouflon. Regardless of the method of analysis used, patterns of multiple hybridization events were observed within all North African populations, leading to a heterogeneous genetic architecture that varies according to the breed. The Barbarine population showed the lowest genetic heterogeneity and major southwest Asian ancestry, providing additional support to the Asian origin of the North African fat-tailed sheep. All other breeds presented substantial Merino introgression ranging from 15% for D'man to 31% for Black Thibar. We highlighted several signals of ancestral introgression between North African and southern European sheep. In addition, we identified two opposite gradients of ancestry, southwest Asian and central European, occurring between North Africa and central Europe. Our results provide further evidence of the weak global population structure of sheep resulting from high levels of gene flow among breeds occurring worldwide. At the regional level, signs of recent admixture among North African populations, resulting in a change of the original genomic architecture of minority breeds, were also detected.

Stroke and syphilis: A retrospective study of 53 patients.

OBJECTIVE: The aim of this study was to describe the clinical, biological and radiological characteristics of patients with syphilitic vasculitis, and to assess the outcome after treatment. METHODOLOGY: A retrospective review was carried out based on the records of patients with ischemic stroke, and reactive CSF TPHA and VDRL results. None of these patients showed symptoms of any other diseases or had received high doses of penicillin. RESULTS: A total of 53 patients with stroke met the diagnostic criteria for syphilitic arteritis. Their average age was 41±12 years. Nine patients had a history of genital ulcer (17%), and the median duration of illness after presenting a chancre was 8 [range: 1-14] years. A prodromal syndrome was seen in 27 patients (50.9%) and included changes in mental status in 14 patients (26.4%), seizures in 10 cases (18.9%), headache in eight (15.1%) and memory loss in seven (13.2%). Neurological events included focal motor deficits in 29 cases (54.7%), ataxia in 11 (20.8%) and movement disorders in 15 (28.3%). HIV serology was performed in 31 patients and proved negative in every case. Disease evolution was generally favorable: 12 patients (22.6%) were autonomous at the time of hospital discharge; 29 (54.7%) had partially recovered; and only seven (13.2%) still had signs of severe sequelae. CONCLUSION: A diagnosis of syphilitic stroke should be suspected in young patients as a manifestation of syphilis, and tests for neurosyphilis should be routine in neurology departments to make a prompt diagnosis, thereby preventing psychological sequelae.

Association of vitamin D status with multiple sclerosis in a case-control study from Morocco.

BACKGROUND: Growing evidence suggests that hypovitaminosis D contributes to the pathogenesis of multiple sclerosis (MS). OBJECTIVE: This study aimed to evaluate whether vitamin D levels are associated with having MS and some of its characteristics in the Moroccan population. METHODS: Using liquid chromatography-tandem mass spectrometry, the 25(OH)D3 metabolite was measured to quantify vitamin D serum levels (DSLs) in 113 patients with MS and 146 healthy controls matched for gender and age. DSLs were then compared between patients and controls, with correlations sought between DSLs and gender, age at onset, disease duration, MS type, degree of disability (EDSS score) and disease severity (MSSS) in patients. RESULTS: Hypovitaminosis D (DSL<30ng/mL) was observed in 97.3% of MS patients and in 98.6% of controls. Although the mean DSL was slightly lower in patients (11.69±6.97ng/mL) than in controls (12.98±6.58ng/mL), there was no significant association between DSL and MS status (P=0.131). Similarly, among patients, no apparent association was found between DSL and MS type (P=0.214), EDSS score (P=0.076) or MSSS (P=0.772). CONCLUSION: Our study suggests that DSL is not associated with having MS nor with MS type, degree of disability or disease severity in the Moroccan population. On the other hand, DSL was lower in women and decreased with age.

Vitamin D deficiency and its role in neurological conditions: A review.

This review exposes recent advances on the role of vitamin D, cholecalciferol, a secosteroid, in the central nervous system. In humans, vitamin D arises from cutaneous transformation of 7-dehydrocholesterol under the effect of UVB exposure or from food intake. Vitamin D has an immunomodulatory role through its anti-inflammatory and anti-autoimmune actions. In the nervous system, vitamin D is involved in the regulation of calcium-mediated neuronal excitotoxicity, in the reduction of oxidative stress, and in the induction of synaptic structural proteins, neurotrophic factors and deficient neurotransmitters. Reduced exposure to sunlight and low food intake can lead to vitamin D deficiency. Increasing evidence highlights the impact of vitamin D deficiency as a favoring factor in various central or peripheral neurological diseases, especially multiple sclerosis and several neurodegenerative diseases, such as amyotrophic lateral sclerosis, Parkinson's disease and Alzheimer's disease. Recently, several clinical trials on vitamin D supplementation stressed the role of vitamin D as a protective and/or prognostic factor in the onset and progress of such neurological conditions.

Evaluation of retinal nerve fiber layer thickness measured by optical coherence tomography in Moroccan patients with multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by focal inflammatory infiltrates, demyelinating lesions and axonal injury. The purpose of the study was to evaluate the retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT) in Moroccan patients with MS and to assess the relationship between RNFL thickness and disease duration, Expanded Disability Status Scale (EDSS) score, visual acuity and automated visual field indices. MATERIALS AND METHODS: Thirty-one patients with definite MS and thirty-one disease-free controls were enrolled in the study. After neurologic consultation, ophthalmologic examination including visual acuity, automated visual field testing and OCT were performed. RESULTS: Significant differences between both groups were observed in OCT parameters (total, temporal and macular ganglion cell layer) with lower thickness in the MS group. In patients without a history of optic neuritis, there were statistically significant inverse correlations between total RNFL thickness and disease duration, neurologic disability evaluated by the EDSS, logMAR visual acuity and automated visual field indices. CONCLUSIONS: OCT seems to be a reproducible test to detect axonal loss of ganglion cells in MS. Further and larger longitudinal prospective studies would be valuable to assess the evolution over time of the RNFL measurements in Moroccan MS patients.

A clinical study of non-parkinsonian tremor in Moroccan patients.

OBJECTIVE: To report the characteristics of the most frequent tremors in a population of Moroccan patients. BACKGROUND: Tremor is the most common movement disorder. It implies a wide variety of disorders with Parkinson's disease and essential tremor being the most frequent. METHODS: A retrospective study of 148 patients with tremor referred to our movement disorders outpatient clinic was performed. Clinical features and treatment regimens were analyzed. Patients with parkinsonian tremor were excluded. RESULTS: We included 62 patients with non-parkinsonian tremor. The etiologies were as follows: essential tremor (54.8%), dystonic tremor (19.4%), tremor associated with dystonia (14.5%), enhanced physiological tremor (3.2%), cerebellar tremor (3.2%), psychogenic tremor (3.2%) and Holmes' tremor (1.6%). The characteristics of essential tremor patients were analyzed. Female patients accounted for 67.6% of patients. Mean age at the onset of tremor was 52.2 ± 16.4 years. Family history of tremor was reported in 17.6% of cases. Tremor affected the arms (94.1%), head (52.9%), voice (35.3%) and legs (8.8%). Tremor was bilateral in 87.5% but was asymmetrical in 50% of patients. Patients had postural tremor (76.5%), kinetic tremor (79.4%) and rest tremor (associated in 11.8%). Treatment relied on propranolol (88.3%), primidone (14.7%), gabapentin (14.7%), clonazepam (14.7%), alprazolam (11.8%), topiramate (5.9%) and, in one patient, radiosurgery. CONCLUSIONS: Essential tremor was the predominant diagnosis, confirming its high prevalence. There was a predominance of female patients and a peak of age at onset in the fifth and sixth decades. Asymmetry of the disease was noted in half of patients.

The influence of phosphorus content on magnetic anisotropy in ferromagnetic (Ga, Mn) (As, P)/GaAs thin films.

The magnetic anisotropy of the ferromagnetic semiconductor (Ga, Mn) (As, P) is studied in a material-specific microscopic k ⋅p approach. We calculate the electronic energy band structure of (Ga, Mn) (As, P) quaternary ferromagnetic alloys using a 40-band k ⋅p model and taking into account the s, p-d exchange interaction and the strain of the (Ga, Mn) (As, P) layer on a GaAs substrate. We determine the variations of the carrier effective masses in the strained (Ga, Mn) (As, P)/GaAs system. The magnetic anisotropy constants obtained from our simulations using a mean-field model are compared with the experimental ones determined by ferromagnetic resonance spectroscopy on a set of samples with constant manganese concentration and varying phosphorus concentration. An excellent quantitative agreement between experiment and theory is found for the uniaxial out-of-plane and cubic in-plane anisotropy parameters.

Genetic factors and multiple sclerosis in the Moroccan population: a role for HLA class II.

BACKGROUND AND OBJECTIVE: Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease of the central nervous system that mainly affects young adults. The association between susceptibility to MS and HLA class II genes, in particular the DRB1*15 allele, has been reported in diverse ethnic groups. The aim of our study was to investigate the distribution of HLA-DRB1* and -DQB1* alleles in Moroccan population and their implication in the susceptibility to the disease. METHODS: Fifty-seven MS patients were compared to 172 healthy controls unrelated to one another and matched by age, sex and ethnic origin. HLA class II (DRB1* and DQB1*) typing was performed by PCR-SSP and/or Luminex (PCR-SSO). Allelic and haplotypic frequencies, P-values, odds ratio (OR) and 95% confidence interval (CI) were calculated using the software SPSS. RESULTS: A significant increase of DRB1*15 allele frequency (17.6% vs 8.4%, OR=2.67, 95% CI=1.36-5.23, P=0.004) and HLA-DRB1*15-DQB1*06 haplotype (8.8% vs 4.08%, OR=2.78, 95% CI=1.41-5.48, P=0.002) were observed in Moroccan MS patients. No association of the DR15 allele with sex or age at onset was appreciated. Concerning HLA-DQB1* alleles, no significant difference between patients and controls was found. CONCLUSIONS: Our results reveal a role for HLA-DRB1*15 allele molecules in the predisposition of Moroccan patients to MS. Although this study should be confirmed on a larger sample size, it analyzes for the first time the possible role of a genetic marker for susceptibility to MS in Moroccan population.

Profile of multiple system atrophy in Moroccan patients attending a movement disorders outpatient clinic in Rabat university hospital.

INTRODUCTION: Multiple system atrophy (MSA) is a sporadic and rapidly progressive neurodegenerative disorder of poor prognosis, characterised clinically by any combination of parkinsonian, autonomic, cerebellar, or pyramidal signs. We report our experience in movement disorders consultation concerning the clinical presentation and the course of MSA in Moroccan patients. METHODS: A retrospective review of the medical records of 17 patients with diagnosis of MSA seen in our outpatient clinic from January 2007 to December 2010. RESULTS: In our 17 patients, 76.5% were men and the mean age of onset was 52±9 years. MSA-P was the major clinical phenotype (82.4%). Eleven patients (64.7%) were classified as having probable MSA and six patients (35.3%) as possible MSA. Dysautonomic features were detected in all patients; urinary symptoms were found in 76.5% of cases and orthostatic hypotension in 64.7%. Treatment regimen included l-Dopa with a mean daily dose of 621.4±346.8mg/day and symptomatic treatment of dysautonomia. The mean duration of disease evolution was of 4.7±1.9 years. DISCUSSION: Our results show a male predominance and an early age of disease onset. MSA-P was the predominant subtype. Our results are similar to the European MSA series. CONCLUSION: Multicentre studies are needed to better characterise MSA in Morocco given the rarity of this disease.

[Atypical metastatic sites for adenocarcinoma of the lung]. / Localisations métastatiques inhabituelles d'adénocarcinome pulmonaire.

Lung carcinomas have a high propensity to metastasize to the liver, adrenal, bone or brain. However, certain atypical intracranial sites may occur. We report two cases of adenocarcinoma of the lung discovered by peculiar brain metastases. The first patient presented with an orbital apex syndrome due to a metastasis to the cavernous sinus with intraorbital extension. The second patient presented with headache and visual loss due to metastasis to the pituitary. Intrasellar and parasellar metastases are rare sequelae of pulmonary neoplasms. Etiological diagnosis is based on imaging and sampling or biopsy. They are often associated with a poor prognosis. The differential diagnosis of an intracranial process in the area of the sella should include metastasis even in the absence of a known primary cancer.

[Quality of life and multiple sclerosis: Arabic language translation and transcultural adaptation of "MSQOL-54"]. / Qualité de vie et sclérose en plaques: traduction en langue arabe et adaptation transculturelle du "MSQOL-54".

INTRODUCTION: Quality of life assessment of multiple sclerosis patients in Morocco appears essential, considering the early age of onset and the significant functional, psychological and social impact of disease symptoms and disorders. Our goal was to translate the MSQOL-54 into Arabic followed by cross-cultural adaptation, and validation of the translated version. METHODS: Patients with multiple sclerosis were recruited over a period of 7 months, from February to August 2007. Sociodemographic data and a detailed clinical description (neurological examination, EDSS, MMS) were collected before administration of the questionnaire. The MSQOL-54 was translated and test validation techniques were applied: back translation, revision by a committee of experts, study of acceptability, multivariate analysis, reliability and clinical validity. RESULTS: Seventy-eight patients were included. There were 23 men and 55 women of various ages, various stages of disability (EDSS from 1 to 8.5) and various clinical forms. Evaluation of the 78 completed questionnaires revealed a satisfactory acceptability considering the limited number of missing answers and the average time to complete the test (24 minutes). The reliability and the multimultivariate analysis were excellent (coefficient of Cronbach ≥0.7 with a percentage of convergence and divergence validity around 100%). A very significant relationship was found between physical scores and EDSS. CONCLUSION: Measuring the quality of life is an approach that confirmed its usefulness through this study. We propose a valid Arabic version of MSQOL-54.

[Multiple sclerosis associated with antiphospholipid syndrome: diagnostic and therapeutic difficulties]. / Sclérose en plaques associée à un syndrome des antiphospholipides : difficultés diagnostiques et thérapeutiques.

Strokes are the main neurological manifestation of antiphospholipid syndrome. Other clinical presentations are possible and may mimic classic symptoms of multiple sclerosis (MS). A 46-year-old woman, with a history of two miscarriages, presented four subacute neurological episodes (optic neuritis, right facial paralysis, paraparesis of the thigh, and right brachial monoparesis). Using McDonald criteria, the diagnosis of multiple sclerosis was retained. Because of the occurrence of thrombocytopenia during a final relapse, we reconsidered the diagnosis of MS. Search for antiphospholipid antibodies was positive. All clinical manifestations and complementary tests were compatible with the diagnosis of antiphospholipid syndrome associated with multiple sclerosis. Given the great similarity of clinical, radiological and biological findings in the two diseases, non-thrombotic neurological manifestations of antiphospholipid syndrome can be difficult to distinguish from MS associated with antiphospholipid syndrome.

Neurological manifestations of Behçet's disease: evaluation of 40 patients treated by cyclophosphamide.

INTRODUCTION: Neurological manifestations in Behçet's disease represent between 4 to 49% of systemic manifestations and remain, in the long term, the leading cause of morbidity and mortality. METHODS: Retrospective series of 40 severe Neurobehçet cases fulfilling the International Study Group criteria for Behçet's disease were consecutively recruited over a period from June 2004 to December 2010. All patients had clinical and ophthalmologic examinations; they underwent laboratory and imaging investigations. They received corticosteroids and cyclophosphamide as initial bolus of 600 mg/m(2) of BSA in the 1st, 2nd, 4th, 6th and 8th day followed by a bolus of 600 mg/m(2) BSA every 2 months for 2 years. Antithrombotic therapy was given to patients with cerebral deep venous thrombosis. Patient follow-up and tolerance to treatment were analyzed. RESULTS: The average age at diagnosis was 34±13 years, with a sex-ratio of 1.78. The clinical presentation was dominated by the meningoencephalitis in 48.8% of cases, cerebral deep venous thrombosis in 43.6% of cases and myelopathy in 7.7% of cases. The 40 patients receiving cyclophosphamide bolus, despite two aggravated cases, evolved positively with clinical improvement and good tolerance. CONCLUSION: The demographic and clinical aspects of our series are similar to those reported in the literature. In contrast to previously reported cases of a poor prognosis in severe neurobehçet's disease, our study suggests that immediate and aggressive treatment by cyclophosphamide may ameliorate the prognosis. However, a multicenter study is needed to confirm the possible efficacy of cyclophosphamide and further assess the long-term tolerance.

[Psychotic disorder revealing epilepsy linked to a dysembryoma of the left hippocampus]. / Trouble psychotique révélant une épilepsie associée à une tumeur dysembryoplasique neuroépithétliale de l'hippocampe gauche.

INTRODUCTION: Psychotic symptoms are a rare but well-known complication of epilepsy. The prevalence is estimated between 4 and 9%. PATIENT: We report a case of a 40-year-old patient, unrecognized epileptic, who presented an acute psychotic syndrome which seemed to be of functional origin, the EEG performed during the episode, and the cerebral CT scan being normal. Nevertheless, the clinical presentation, especially the sudden ending of delusions, led to further investigations. Careful history taking and repeated EEG recordings allowed the diagnosis of partial epilepsy that had begun 17 years earlier and symptomatic of a dysembryoplastic tumour of the left hippocampus revealed by MRI. DISCUSSION AND CONCLUSION: Search for an epileptic origin of an acute psychotic syndrome must always be undertaken by systematic EEG. The possibility of a symptomatic temporal tumor must not be overlooked.

[Stroke revealing granulomatosis]. / Accident vasculaire cérébral révélant une granulomatose.

INTRODUCTION: Central nervous system involvement is rare in Wegener granulomatosis. Stroke is the most common event suggestive of the disease. COMMENT: A 35-year-old woman, who was followed for rhinitis and mild asthma, described gradual decline of visual acuity in the right eye over two months, persistent nasal obstruction and fronto-orbital headache since a few weeks. She presented left hemiparesis due to a stroke, associated with exophthalmos and deficits of the optic nerve and abducens of the right eye. The otolaryngological examination found signs of crusty rhinitis and right nasal stenosis. The diagnosis of Wegener's granulomatosis was established on the basis of the clinical findings, radiological aspects and the presence of ANCA. The patient was treated by antiplatelet agents and high-dose corticosteroids associated with immunosuppressive drugs including cyclophosphamide in a monthly bolus. DISCUSSION: This case illustrates two of the three pathogenic mechanisms that may account for central nervous system involvement in Wegener granulomatosis: vasculitis, extension by contiguity of granulomatous tissue from the nasal cavity or sinuses, and in situ formation of a granuloma into the brain parenchyma or meninges.