RESUMEN
Cereal-legume intercrops are developed mainly in low input or organic farming systems because of the overyielding and numerous ecosystem services they provide. For this management, little advice is available for varietal choice and there are almost no specific breeding programs. Our study aimed to evaluate the mixing ability of a panel of bread wheat genotypes in intercropping and to assess the impact of environment and legume tester choice on this ability. We used partial land equivalent ratios (LERs) to assess the mixing ability of a genotype defined as the combination of its ability to maintain its own yield in intercropping (producer effect, LERw) and to let the mixed species produce (associate effect, LERl). Eight wheat genotypes and 5 legume testers (3 pea and 2 faba bean varieties) were grown in sole crop and in all possible binary intercrops in nine contrasting environments. A mixed model was used to evaluate the effects of wheat genotypes, legume testers, environments, and all the interactions among these 3 factors on LERw and LERl. The chosen wheat genotypes presented contrasting mixing ability, either in terms of producer effect (LERw) or associate effect (LERl). A strong negative correlation was observed between these two components of genotype mixing ability, with an increase in producer effect being generally associated with similar decrease in associate effect, except for three genotypes. The impact of environment on the producer and associate effects was limited and similar between genotypes. Legume tester had a significant effect on both LERw and LERl, making the choice of tester a major issue to reveal the producer or associate effects of wheat genotype. Although the 5 testers showed no significant differences in wheat genotype order for both producer or associate effects, they showed different competitiveness and ability to discriminate genotypes: faba bean was very competitive, resulting in low LERt and low capacity to discriminate wheat genotypes for their mixing ability. On the contrary, pea was less competitive, resulting in higher LERt and better capacity to discriminate wheat genotypes. In particular, the Hr varieties (Geronimo and Spencer) discriminated best the wheat genotypes. Consequences on the implementation of breeding programs for wheat varieties adapted to intercropping are discussed.
RESUMEN
Guillain-Barré syndrome (GBS) is the most common cause of acute neuropathy. It usually onset with a rapidly progressive ascending bilateral weakness with sensory disturbances, and patients may require intensive treatment and close monitoring as about 30% have a respiratory muscle weakness and about 10% have autonomic dysfunction. The diagnosis of GBS is based on clinical history and examination. Complementary examinations are performed to rule out a differential diagnosis and to secondarily confirm the diagnosis. GBS is usually preceded by an infectious event in ≈ 2/3 of cases. Infection leads to an immune response directed against carbohydrate antigens located on the infectious agent and the formation of anti-ganglioside antibodies. By molecular mimicry, these antibodies can target structurally similar carbohydrates found on host's nerves. Their binding results in nerve conduction failure or/and demyelination which can lead to axonal loss. Some anti-ganglioside antibodies are associated with particular variants of GBS: the Miller-Fisher syndrome, facial diplegia and paresthesias, the pharyngo-cervico-brachial variant, the paraparetic variant, and the Bickerstaff brainstem encephalitis. Their semiological differences might be explained by a distinct expression of gangliosides among nerves. The aim of this review is to present pathophysiological aspects and the diagnostic approach of GBS and its variants.
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Encefalitis , Síndrome de Guillain-Barré , Síndrome de Miller Fisher , Encefalitis/complicaciones , Gangliósidos , Síndrome de Guillain-Barré/diagnóstico , Humanos , Síndrome de Miller Fisher/complicaciones , Debilidad MuscularRESUMEN
INTRODUCTION: Cerebral venous thrombosis (CVT) are underdiagnosed in sub-saharan Africa where publications are uncommon. Our study aim was to describe the CVT diagnostic and therapeutic features through a senegalese case series. PATIENTS AND METHOD: A monocentric retrospective and prospective study was conducted at the adult Neurology department of Fann Teaching Hospital in Dakar (Senegal), between January 01, 2013 and April 30, 2020. It had included all CVT cases diagnosed by neurovascular imaging. RESULTS: Seventy CVT cases were collected including 48 women (68.6%). The average age of the patients was 35.2±14 years. The main neurological signs were headache (92.8%) and motor deficit (41.4%), with subacute onset in 67.2% of cases. The superior sagittal sinus (54.3%) and the transverse sinus (38.6%) were the most affected with multiple involvements in 27 patients (38.6%). Thirty patients (42.8%) had indirect parenchymal signs such as venous infarction (15.7%), cerebral edema (11.4%) or intracerebral hemorrhage (12.8%). The etiological factors were mostly infectious (41.4%) with meningoencephalitis (12.8%) and otorhinolaryngological infection (10%). Gyneco-obstetric factors (27%) and Behçet's disease (7%) were the main aseptic factors. In the short-term clinical course, curative anticoagulation (98.6%) had enabled a favourable outcome (mRS 0-1) in half of the patients. CONCLUSION: Our study, the largest series in sub-saharan Africa to this date, confirms that CVT is a young women disease. Infectious etiology is the most frequent at the Fann national teaching hospital (41.4% in Dakar against 6.5% in Germaine Bousser's series) even if the etiological assessment is limited by financial constraints (no coagulopathy/thrombophilia check-up).
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Trombosis Intracraneal , Neurología , Trombosis de la Vena , Adulto , África del Sur del Sahara , Femenino , Hospitales de Enseñanza , Humanos , Persona de Mediana Edad , Embarazo , Estudios Prospectivos , Estudios Retrospectivos , Senegal , Adulto JovenRESUMEN
Neuro-Behçet (NB) African studies are mainly North African, but Sub-Saharan Africa is not to be outdone. Our aim was to describe diagnostic and therapeutic features of NB in a Senegalese series collected in Dakar. This was a descriptive and retrospective study conducted at the Neurology department of Fann Teaching Hospital in Dakar, Senegal. All patients who met the NB's diagnostic criteria were included. Sixteen patients were collected, 14 males and 2 females with an average age of 40 years [18-71]. The main neurological signs were motor deficit (13 cases), headache (10 cases), and language disorders (4 cases). Extra-neurological signs were dermatological (14 cases), ocular (2 cases), and articular (2 cases) with aseptic unilateral gonarthritis. Fever was present in 9 patients. Neurological involvement was mostly isolated parenchymal (8 cases) or mixed (6 cases). The main clinical forms of NB were rhombencephalitis (8 cases) and retrobulbar optic neuritis (4 cases). Seven patients had a cerebral angio-Behçet with cerebral venous thrombosis (3 cases), ischemic stroke (2 cases), and intracerebral hematoma (2 cases). Under prednisone (16 cases) and azathioprine (3 cases), the short-term clinical outcome was mostly favorable (14 cases) with a modified Rankin scale at 2. NB is an under-diagnosed adult male disease in Sub-Saharan Africa and further studies are needed.
Les études africaines sur le neuro-Behçet (NB) sont majoritairement maghrébines, mais l'Afrique noire n'est pas en reste. L'objectif de l'étude était de décrire les particularités diagnostiques et thérapeutiques du NB dans une série sénégalaise colligée à Dakar. Il s'agit d'une étude rétrospective à visée descriptive menée à la clinique de neurologie du centre hospitalier universitaire de Fann de Dakar, au Sénégal. Tous les patients répondant aux critères diagnostiques de NB ont été inclus. Seize patients ont été colligés, 14 hommes et deux femmes avec un âge moyen de 40 ans [1871]. Les principaux signes neurologiques étaient un déficit moteur (13 cas), des céphalées (10 cas) et un trouble du langage (4 cas). Les signes extraneurologiques étaient dermatologiques (14 cas), oculaires (2 cas) et articulaires (2 cas) à type de gonarthrite unilatérale aseptique. Une fièvre était présente chez neuf patients. L'atteinte neurologique était majoritairement parenchymateuse isolée (8 cas) ou mixte (6 cas). Les principales formes cliniques de NB étaient la rhombencéphalite (8 cas) et la névrite optique rétrobulbaire (4 cas). Sept patients avaient un angio-Behçet cérébral à type de thromboses veineuses cérébrales (3 cas), d'infarctus cérébraux (2 cas) et d'hématomes intracérébraux (2 cas). Sous prednisone (16 cas) et azathioprine (3 cas), l'évolution clinique à court terme était majoritairement favorable (14 cas) avec un score de Rankin modifié de 2 au moment de l'exeat. Le NB est une maladie de l'homme adulte sous-diagnostiquée en Afrique noire. Des études ultérieures multicentriques nationales et sous-régionales sont souhaitables.
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Síndrome de Behçet/complicaciones , Síndrome de Behçet/diagnóstico , Síndrome de Behçet/terapia , Trombosis Intracraneal/diagnóstico , Trombosis Intracraneal/etiología , Trombosis Intracraneal/terapia , Adolescente , Adulto , África del Sur del Sahara/epidemiología , Anciano , Síndrome de Behçet/epidemiología , Hemorragia Cerebral/diagnóstico , Hemorragia Cerebral/epidemiología , Hemorragia Cerebral/etiología , Hemorragia Cerebral/terapia , Estudios de Cohortes , Femenino , Hospitales de Enseñanza , Humanos , Trombosis Intracraneal/epidemiología , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Senegal/epidemiología , Adulto JovenRESUMEN
BACKGROUND AND PURPOSE: Resistance to blood flow in the cerebral drainage system may affect cerebral hemodynamics. The objective of the present study was to use phase-contrast MRA to quantify resistance to drainage of blood across branches of the venous sinus tree and to determine whether the resistance to drainage values correlated with internal jugular vein outflows. MATERIALS AND METHODS: We performed whole-head phase-contrast MRA and 2D phase-contrast MR imaging in 31 healthy volunteers. Vascular segmentation was applied to the angiograms, and the internal jugular vein velocities were quantified from the flow images. Resistance to drainage across branches of the venous sinus tree was calculated from the segmented angiograms, by using the Poiseuille equation for laminar flow. Correlations between the values of resistance to drainage and internal jugular vein outflow measurements were assessed by using the Spearman ρ. RESULTS: The overall mean resistance to drainage of the venous sinus tree was 24 ± 7 Pa s/cm3. The mean resistance to drainage of the right side of the venous sinus tree was 42% lower than that of the left side (P < .001). There were negative correlations between the values of resistance to drainage and internal jugular vein outflows on both the left side of the venous sinus tree (R = -0.551, P = .002) and the right side (R = -0.662, P < .001). CONCLUSIONS: Phase-contrast MRA is a noninvasive means of calculating the resistance to drainage of blood across the venous sinus tree. Our approach for resistance to drainage quantification may be of value in understanding alterations in the cerebral venous sinus drainage system.
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Circulación Cerebrovascular/fisiología , Senos Craneales/diagnóstico por imagen , Senos Craneales/fisiología , Hemodinámica/fisiología , Angiografía por Resonancia Magnética/métodos , Adulto , Femenino , Humanos , Venas Yugulares/fisiología , MasculinoRESUMEN
Hematological manifestations can lead to diagnosis of pernicious anemia, also known as Biermer disease and Biermer anemia. This disease has been little studied among black Africans. Our aim is to describe its diagnostic and therapeutic aspects and outcome in our practice. This descriptive study retrospectively examined the records of 66 patients with pernicious anemia seen at the Clinical Hematology Unit of Le Dantec Hospital in Senegal from January 1, 2000, to June 30, 2014. Symptoms were anemic syndrome (40 cases), hemolytic anemia (13), anemic heart failure (7), isolated pallor of the mucous membranes (5), and venous thrombosis (2). Their mean hemoglobin on diagnosis was 6.52 g/dL [1.3-15.2 g/dL], macrocytosis (52), normocytosis (14), hypochromia (4), thrombocytopenia (39), and leukopenia (28 cases). Cytopenia was associated with pancytopenia (25) and bicytopenia (18). Cytologic abnormalities were documented in 42 cases: megaloblastic erythrosis (37 cases) and hypersegmented neutrophils (24 cases). After vitamin B12 therapy - intramuscular (52) or oral (14) -, a reticulocyte crisis was noted on the 8th day and followed by correction of the blood count. Macrocytic anemia, frequently associated with thrombocytopenia and/or leukopenia, is the main hematologic sign evoking pernicious anemia. Venous thrombosis is a rare circumstance of diagnosis that must not be ignored. Intramuscular or oral vitamin B12 is recognized to be effective in these cases and reverses hematological manifestations.
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Anemia Perniciosa/sangre , Anemia Perniciosa/diagnóstico , Femenino , Hematología , Unidades Hospitalarias , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , SenegalRESUMEN
Introduction : La sarcoïdose est une granulomatose systémique de cause inconnue. Son association avec une amylose a été exceptionnellement décrite. Nous en rapportons une observation association.Observation : Une patiente âgée de 68 ans était admise dans notre service pour exploration de troubles psycho-comportementaux associés à une macro-polyadénopathie. Le diagnostic d'une sarcoïdose à localisation médiastino-ganglionnaire, cutanée et neurologique était retenu. La biopsie des salivaires accessoires mettait en évidence des dépôts amyloïdes. Le bilan de retentissement de l'amylose objectivait une altération de la fonction rénale et uneprotéinurie à 2,36 g/24H. La corticothérapie associée à l'hydroxy-chloroquine a été instituée. L'évolution était favorable. Conclusion : Cette observation illustre l'intérêt de la recherche systématique d'une amylose au cours de la sarcoïdose. La biopsie des glandes salivaires accessoires est de par son innocuité, la technique de référence dans l'amylose systémique du sujet âgé
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Anciano , Amilosa , Sarcoidosis/complicaciones , SenegalRESUMEN
AIM: To present the results of multidisciplinary care model for excised women. PATIENTS AND METHODS: Qualitative retrospective study on multidisciplinary care between 2007 and 2012 within Excised Women Care Unit. Patients are seen by three specialists: a gynecologist obstetrician, a psychotrauma therapist and anthropologist, a psycho-sexologist. The Unit welcomes any excised woman, whatever are her demands. Women wishing for a clitoridian surgery meet systematically the three specialists. The study covers a population of 270 women, most of them aged between 18 and 40years. RESULTS: The presented results are related to women having asked for clitoridian surgery. Two outstanding results come out from multidisciplinary care: few women finally go for surgery, and a high rate of patients wishing for surgery present a sexual trauma other than female genital mutilation/cutting. CONCLUSION: The importance of the psychotraumatic and interpersonal dimension (marital - familial) in the problems presented by the patients indicates that the "repair" of excision cannot be reached by the sole surgery and requires a medical, psychological and sexological management.
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Circuncisión Femenina , Grupo de Atención al Paciente , Adolescente , Adulto , Femenino , Humanos , Estudios Retrospectivos , Adulto JovenRESUMEN
UNLABELLED: This study sought to assess the prevalence of lupus nephropathy and to determine its clinical, histological, therapeutic and outcome profiles. PATIENTS AND METHODS: This retrospective study examined records covering a 10-year period from 1999 to 2009 at the nephrology department of the Aristide Le Dantec University Hospital Center. RESULTS: The records showed 43 patients with systemic lupus erythematosus (SLE), and 72% had lupus nephritis. The patients' mean age was 32.9 years; 40 were women and 3 men, for a sex ratio of 0.075. The lupus nephritis led to discovery of SLE in 27.9%. The mean proteinuria concentration was 2.01 g/dL. Seventeen patients had impaired renal function, and 26 had renal biopsies. It found class II nephritis in 2 patients, class IV in 10, and class V in 12. In addition, fifteen patients received combined corticosteroid + immunosuppressant treatment. Four patients died during the study period, one from SLE activity, two from complications of renal failure, and the fourth from sepsis. CONCLUSION: A larger study would be useful to assess more acurately the prevalence of various classes and severity of lupus nephropathy among blacks living in sub-Saharan Africa.
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Lupus Eritematoso Sistémico/epidemiología , Nefritis Lúpica/epidemiología , Adulto , Población Negra , Femenino , Humanos , Lupus Eritematoso Sistémico/diagnóstico , Nefritis Lúpica/clasificación , Masculino , Prevalencia , Proteinuria/etiología , Estudios Retrospectivos , SenegalRESUMEN
Pernicious anemia appears classically by macrocytosis. We report a case of a late discovered Biermer disease, on a 42-year-old young black woman. The reason was an unusual aspect of this disease in a context of betathalassemia. The patient presented chronic anemia which evolved during about ten year. Biology showed a normocytosis and signs of hemolysis according to beta-thalassemia. This was confirmed by an electrophoresis showing 9.1 % of fraction F some haemoglobin. Since this date, the patient was treated by folic acid alone with periodic transfusions of red blood cell. She presented eight years after the beginning of her disease, neurological deterioration. Diagnosis of pernicious anemia was finally established up on histological gastritis, low level of the blood rate of vitamin B12, macrocytosis, and presence of intrinsic anti-factor and parietal anti-cells antibodies.
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Anemia Perniciosa/diagnóstico , Talasemia beta/complicaciones , Adulto , Anemia Hipocrómica/complicaciones , Anemia Perniciosa/sangre , Anemia Perniciosa/complicaciones , Anemia Perniciosa/tratamiento farmacológico , Anemia Perniciosa/inmunología , Anemia Perniciosa/terapia , Autoanticuerpos/sangre , Autoanticuerpos/inmunología , Autoantígenos/inmunología , Terapia Combinada , Diagnóstico Tardío , Progresión de la Enfermedad , Transfusión de Eritrocitos , Femenino , Hemoglobina Fetal/análisis , Ácido Fólico/uso terapéutico , Humanos , Factor Intrinseco/inmunología , Deficiencias de Hierro , Parestesia/etiología , Células Parietales Gástricas/inmunología , Vitamina B 12/sangreRESUMEN
OBJECTIVE: In response to the lack of cancer register and paucity of publications on esophageal cancer in Senegal, this retrospective descriptive single-center study was undertaken to determine epidemiological, clinical, endoscopic and histological features of the disease at a digestive endoscopy center in Dakar. PATIENTS AND METHOD: Reports describing upper digestive tract endoscopy procedures performed at the Aristide Le Dantec Teaching Hospital in Dakar between January 2006 and December 2009 were reviewed. Cases involving histologically confirmed esophageal cancer were compiled and patient data including age, sex, and indication for endoscopy as well as endoscopic and histological findings were analyzed. RESULTS: A total of 78 reports were collected including 76 patients with suitable data for analysis. Esophageal cancer accounted for 0.97% of upper digestive tract endoscopy procedures performed. Mean patient age was 49 years and the sex-ratio was 1.9. The main indication for endoscopy was dysphagia (92.1%). The most frequent endoscopic finding involved budding lesions with (42%) or without (29%) ulceration. The most common location was the middle third of the esophagus (50%). The most frequent histological type was squamous cell carcinoma (92.1%). CONCLUSION: Esophageal cancer observed at the endoscopy center of the Aristide Le Dantec Teaching Hospital in Dakar mainly affects young male adults. Lesions are generally located in the middle third of the esophagus and corresponded to squamous cell cancer. There is a need to establish a cancer register and to conduct multicentric studies to gain insight into risk factors for esophageal cancer in Senegal.
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Neoplasias Esofágicas/patología , Esofagoscopía , Adenocarcinoma/epidemiología , Adenocarcinoma/patología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Células Escamosas/epidemiología , Carcinoma de Células Escamosas/patología , Niño , Trastornos de Deglución/etiología , Neoplasias Esofágicas/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Senegal/epidemiología , Adulto JovenRESUMEN
The structural optimization of highly mesoporous silica thin film templated with Brij58 is reported in this paper. The best conditions for obtaining well organized films are studied as a function of the concentration of surfactant, the relative humidity (RH) and the aging time of the solutions used in the dip-coating process. We first show on the basis of the results obtained by small angle x-ray scattering (SAXS) experiments on the binary system Brij58/water that the structure of the films determined by grazing incidence (GI) SAXS experiments can be explained according to a specific equation involving the initial masses of the sol constituents. Then the structural properties of the films are investigated by x-ray reflectivity (XRR) and GISAXS before and after removing the surfactant. The mesoporosities and morphology of the films are determined by analyzing the reflectivity curves of the highly ordered silica thin films in the cubic phase.
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Cetomacrogol/química , Ensayo de Materiales/métodos , Membranas Artificiales , Dióxido de Silicio/química , Difracción de Rayos X/métodos , Porosidad , Propiedades de Superficie , Tensoactivos/químicaRESUMEN
An effective connectivity study was carried out on 16 young, healthy subjects performing an alertness task. The objective of this study was to develop and to evaluate a putative network model of alertness by adapting structural equation modeling to fMRI data. This study was designed to evaluate the directed interactivity of an attentional network during intrinsic and phasic alerting tasks. On the basis of theoretical hypotheses, clinical observations, behavioral data and neuroimaging studies, it was hypothesized that neural circuits in the right hemisphere including the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex, inferior parietal cortex and the thalamus were involved. The results of this study support the existence of a common network of activated areas with significant path coefficient differences between intrinsic and phasic alertness. Functional interactivity was significantly reinforced during the phasic alertness task and appeared to preferentially involve activity in the DLPFC region, whereas the path coefficients of the model were well-balanced during intrinsic alertness. This study highlights the predominant role of the DLPFC region in maintenance of a state of alertness and in temporal preparation during an alertness task.
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Atención/fisiología , Encéfalo/fisiología , Modelos Neurológicos , Adulto , Mapeo Encefálico , Señales (Psicología) , Femenino , Estado de Salud , Humanos , Imagen por Resonancia Magnética , Masculino , Vías Nerviosas/fisiología , Pruebas Neuropsicológicas , Tiempo de Reacción , Procesamiento de Señales Asistido por ComputadorRESUMEN
INTRODUCTION: Rectal bleeding is a common reason for seeking medical attention and can lead to diagnosis of serious disease. The purpose of this report is to describe lesions discovered by coloscopy in patients assessed for rectal bleeding in Dakar, Senegal. PATIENTS AND METHODS: This retrospective study was carried out from January 2006 to December 2008 at the Aristide Le Dantec University Medical Center in Dakar. Coloscopy reports involving patients presenting with rectal bleeding were compiled. Age, quality of preparation, use of sedation, and lesions observed were analyzed. RESULTS: A total of 143 patients underwent coloscopy for rectal bleeding. Mean patient age was 51.3 years (range, 2 to 85 years) and the sex ratio was 1.7 (90 men). Preparation was considered as good in 55.5% of cases. Sedatives were used in 57% of cases. Coloscopy findings were normal in 9.8% of cases. The most common lesions were hemorrhoids (53.14%), rectocolitis (17.5%), cancer (11.9%), polyps (11.2%), and diverticulosis (11.2%). Multiple lesions were found in 20 patients (14%). CONCLUSION: Coloscopy for assessment of rectal bleeding in Dakar revealed a range of lesions with hemorrhoids and rectocolitis accounting for most.
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Colonoscopía , Hemorragia Gastrointestinal/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Neoplasias Colorrectales/diagnóstico , Diverticulosis del Colon/diagnóstico , Femenino , Hemorroides/diagnóstico , Humanos , Pólipos Intestinales/diagnóstico , Masculino , Persona de Mediana Edad , Proctocolitis/diagnóstico , Recto , Estudios Retrospectivos , Senegal , Adulto JovenRESUMEN
Introduction :La Reticulohistiocytose Multicentrique (RHM) est une affection peu decrite dans la litterature. Nous rapportons deux observations de RHM faites a Dakar; caracteristiques par l'agressivite des lesions et la presentation cutanee pure dans un cas.Observations : La premiere observation concernait une patiente agee de 34 ans admise pour des papulo nodules dissemines; une polyarthrite bilaterale asymetrique destructrice n'epargnant pas les inter-phalangiennes distales et un epanchement sero-hematique aux genoux. La deuxieme observation etait faite chez une patiente agee de 26 ans qui avait des papulo-nodules dissemines depuis 10 ans. L'examen histologique en faveur de la RHM dans les deux cas; montrait une infiltration intradermique d'histiocytes multinucleees sans plasmocytes ni polynucleaires ni cellules xanthomisees. La corticotherapie etait decevante dans la premiere observation. La surveillance etait indiquee dans le deuxieme cas. Conlusion : La RHM est une maladie rare chronique handicapante a localisation tegumentaire diffuse isolee exceptionnelle en Afrique
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Artritis Reumatoide , Informes de Casos , Histiocitosis , Nódulo ReumatoideRESUMEN
PURPOSE: This fMRI study investigated phonological and lexicosemantic processing in dyslexic and in chronological age- and reading level-matched children in a pseudoword reading task. MATERIALS AND METHODS: The effective connectivity network was compared between the three groups using a structural model including the supramarginal cortex (BA 40; BA: Brodmann area), fusiform cortex (BA 37) and inferior frontal cortex (BA 44/45) areas of the left hemisphere. RESULTS: The results revealed differences in connectivity patterns. In dyslexic patients, in contrast with chronological age- and reading level-matched groups, no causal relationship was demonstrated between BA 40 and BA 44/45. However, a significant causal relationship was demonstrated between BA 37 and BA 44/45 both in dyslexic children and in the reading level-matched group. CONCLUSIONS: These findings were interpreted as evidence for a phonological deficit in developmental dyslexia.
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Encéfalo/fisiopatología , Dislexia/fisiopatología , Lectura , Adulto , Corteza Cerebral/patología , Corteza Cerebral/fisiopatología , Dislexia/patología , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Modelos Neurológicos , Modelos Estadísticos , Vías Nerviosas/fisiopatología , Pruebas Neuropsicológicas , Oxígeno/sangre , Tiempo de Reacción/fisiologíaRESUMEN
After having provided a brief reminder of the principle of the blood oxygen level-dependent (BOLD) contrast effect, the physiological bases of brain activity and the concepts of functional integration and effective connectivity, we describe the most recent approaches, which permit to explore brain activity and putative networks of interconnected active areas in order to examine the normal brain physiology and its dysfunctions. We present various methods and studies of brain activity analysis clinically applicable, and we detail the concepts of functional and effective connectivity, which allow to study the cerebral plasticity which occurs at the child's during the maturation (e.g., dyslexia), at the adult during the ageing (e.g., Alzheimer disease), or still in schizophrenia or Parkinson disease. The study of specific circuits in networks has to allow defining in a more realistic way the dynamic of the central nervous system, which underlies various cerebral functions, both in physiological and pathological conditions. This connectivity approach should improve the diagnostic and facilitate the development of new therapeutic strategies.
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Encefalopatías/patología , Encefalopatías/fisiopatología , Imagen por Resonancia Magnética , Encefalopatías/terapia , HumanosRESUMEN
Functional magnetic resonance imaging (fMRI) was used to assess the contributions of movement preparation and execution of a visuomotor task in a cerebral motor network. The functional connectivity of the voxel time series between brain regions in the frequency space was investigated by performing spectral analysis of fMRI time series. The regional interactivities between the two portions of the supplementary motor area (pre-SMA and SMA-proper) and the primary motor cortex (M1), defined as a seed region, were evaluated. The spectral parameter of coherence was used to describe a correlation structure in the frequency domain between two voxel-based time series and to infer the strength of the functional interaction within our presumed motor network of connections. The results showed meaningful differences of the functional interactions between the two portions of the SMA and the M1 area depending on the task conditions. This approach demonstrated the existence of a functional dissociation between the pre-SMA and SMA-proper subregions. We therefore conclude that spectral analysis is useful for identifying functional interactions of brain regions and might provide a powerful tool to quantify changes in connectivity profiles associated with various components of an experimental task.