Identification of novel mutations in WFS1 and genotype-phenotype correlation in Wolfram syndrome

Mutations in the WFS1 gene have been reported in Wolfram syndrome (WS), an autosomal recessive disorder defined by early onset of diabetes mellitus (DM) and progressive optic atrophy. Because of the low prevalence of this syndrome and the recent identification of the WFS1 gene, few data are available concerning the relationships between clinical and molecular aspects of the disease. Here, we describe 12 patients from 11 families with WS. We report on eight novel (A214fsX285, L293fsX303, P346L, I427S, V503fsX517, R558C, S605fsX711, P838L) and seven previously reported mutations. We also looked for genotype-phenotype correlation both in patients included in this study and 19 additional WS patients that were previously reported. Subsequently, we performed a systematic review and meta-analysis of five published clinical and molecular studies of WFS1 for genotype-phenotype correlation, combined with our current French patient group for a total of 96 patients. The presence of two inactivating mutations was shown to predispose to an earlier age of onset of both DM and optic atrophy. Moreover, the clinical expression of WS was more complete and occurred earlier in patients harboring no missense mutation.     

Vanilloïdes, cannabinoïdes et nociception: aspects anatomiques

Résumé  Les vanillo?des et les cannabino?des, deux substances extraites respectivement du piment du Chili et du cannabis, sont impliqués dans la douleur. Nous verrons ici comment la localisation des récepteurs cannabino?des CB1 et CB2 et des récepteurs vanillo?des VR1 peut apporter des renseignements précieux pour comprendre leu r?le. Les récepteurs VR1 sont localisés dans quatre populations cellulaires de fibres sensorielles impliquées dans la douleur aigu? et chronique. Un contr?le noradrénergique central de la nociception à partir du locus coeruleus par les vanillo?des est aussi vraisemblable. Les cannabino?des sont impliqués dans la modulation de la douleur aigu? ou chronique au niveau spinal par l’intermédiaire de récepteurs CB1 présents sur des afférences primaires, des interneurones inhibiteurs et des astrocytes. Au niveau supraspinal, les cannabino?des sont impliqués dans les contr?les monoaminergiques, sérotoninergiques ou noradrénergiques. Ils pourraient jouer un r?le également dans les régulations centrales du système autonome par la douleur et les aspects psychoaffectifs de la douleur. Les données synthétisées ici suggèrent aussi l’existence de nouveaux types ou sous-types de récepteurs aussi bien pour les cannabino?des que pour les vanillo?des. Enfin, la coexistence, au moins régionale, des récepteurs CB1 et VR1 renforce l’hypothèse récente d’une interaction entre ces deux systèmes.      

First Melody? valve implantations in Africa

Congenital heart lesions involving the right ventricular outflow tract (RVOT) are a common problem in paediatric cardiology. These patients need multiple surgical interventions in the form of valved conduits over a lifetime. Surgical re-valvulation was the standard treatment option until the introduction of percutaneous pulmonary valves over a decade ago. These valves can be used to prolong the lifespan of conduits and reduce the number of re-operations. The Melody® valve (Medtronic, Minneapolis, MN, USA) was introduced as the first dedicated percutaneous pulmonary valve. Percutaneous pulmonary valves can be implanted successfully and have the advantage of short hospitalisations. We describe the first three Melody® valve implantations in Africa.     

Metabolic factors and the foveal avascular zone of the retina in diabetes mellitus

AIM: To study the foveal avascular zone (FAZ) of the central retina in diabetic patients with retinopathy having undergone metabolic evaluation. METHODS: One hundred and ten digital fluorescein angiograms were chosen from our digital image bank after cross matching diabetic patient lists of the ophthalmology and endocrinology departments of our institution. The patients had undergone day visits with systemic, biological and ophthalmologic evaluation, including digital fluorescein angiography. RESULTS: Sex ratio was M 62/F 48. Average age was 52.4 years (+/- 13.8) with 44 type 1 diabetics and 66 type 2. Retinopathy was present in all patients (54 background (BDR), 30 pre-proliferative (PPDR), 26 proliferative (PDR)). Age was positively correlated with FAZ grade (47.3 years +/- 13.2 for normal FAZ, 53.8 years +/- 13.7 for abnormal FAZ, P=0.03). Lipid profile showed a protective tendency of the Apo A1 fraction of cholesterol on macular vascularization (1.7 gr./l in normal FAZ patients vs 1.43 gr./l in abnormal FAZ patients, P=0.004). Body mass index was negatively correlated with macular ischemia (28.11 if FAZ not severely altered, 25.97 if FAZ severely altered, P=0.03). CONCLUSIONS: We found possible relations between BMI and Apo A 1 cholesterol and macular vascularization which may warrant further investigation.     

The inhibitory effects of exogenous arachidonic acid on rabbit platelet aggregation and the release reaction

Although arachidonic acid causes rabbit platelet aggregation and the release of granule contents in suspensions of washed platelets when used in concentrations of approximately 50-300 microM, higher concentrations (500 microM) cause neither aggregation nor release. Suspensions of platelets from rabbits wee exposed to arachidonic acid (250 microM) for 15 min, allowed to recover in the presence of PGE1 for 30 min, washed, and resuspended; in some experiments, the platelets were treated with aspirin before being exposed to arachidonic acid. Aggregation of platelets pretreated with arachidonic acid was inhibited in response to ADP; this effect was greater with the non-aspirin- treated platelets and persisted for at least 4 hr after resuspension. The association of 125I-fibrinogen with the platelets as a result of ADP stimulation was also inhibited. Aggregation and release of granule contents in response to collagen and low concentrations of thrombin was inhibited, but the inhibition could be overcome by higher concentrations. Thrombin induced further release of granule contents from platelets exposed to arachidonic acid without pretreatment with aspirin. Platelets that had been exposed to arachidonic acid, either with or without pretreatment with aspirin, did not aggregate or undergo further release upon stimulation with arachidonic acid after they were washed and resuspended. Inhibition of the lipoxygenase pathway with eicosatetraynoic acid (ETYA) or nordihydroguaiaretic acid (NDGA) did not affect the inhibition caused by arachidonic acid, so it is unlikely that a product of this pathway is responsible for the inhibition. Mixing experiments indicated that the pretreated platelets did not form a thromboxane-A2-like activity, and that they were unresponsive to aggregation and release induced by products formed from arachidonic acid. Experiments with 3H-arachidonic acid showed that after 45 min of incubation with platelets, only 1.1% of the 3H-arachidonic acid remained as free arachidonic acid in the platelets. Although cyclic-AMP was slightly increased 1 min after the addition of arachidonic acid, the cyclic-AMP concentration was the same as that of control platelets after the platelets were washed and resuspended, indicating that increased cyclic-AMP is not likely to be responsible for the persistent inhibitory effect. Thus, the inhibitory effect of pretreatment with arachidonic acid is a general effect on responses to a variety of aggregating agents that act through different mechanisms, and the inhibition is not related to thromboxane-A2 formation. The possibility of membrane perturbation resulting in the unavailability of receptors may explain the persistent inhibitory effect, but the responsible reactions have not been identified.     

Differential expression of CD11b/CD18 (Mo1) and myeloperoxidase genes during myeloid differentiation

During the course of differentiation of early human myeloid cells toward monocytes and granulocytes, cell surface expression of the cell adhesion molecule, CD11b/CD18 (Mo1) increases dramatically and expression of myeloperoxidase (MPO), a bacteriocidal enzyme, decreases markedly. Using the inducible promyelocytic cell line HL-60 as a model, we studied the mRNA expression of these genes. Differentiation of these cells along both a monocytic and a granulocytic pathway demonstrated that the mRNA levels of the two subunits of CD11b/CD18 increased in a pattern temporally and quantitatively similar to the increase in cell surface expression of this heterodimer. In contrast, the expression of MPO mRNA decreased in a temporal and quantitative pattern similar to the known decrease in MPO protein during differentiation, suggesting that regulation of these myeloid-specific proteins may occur at the level of mRNA expression. These findings have important implications with regard to the nature of the block in differentiation in acute nonlymphocytic leukemia and the regulation of myeloid gene expression.     

Recombinant human interleukin-3 stimulation of hematopoiesis in humans: loss of responsiveness with differentiation in the neutrophilic myeloid series

Recombinant human (rh) interleukin-3 (IL-3) stimulated the proliferation and differentiation of erythroid, granulocyte, macrophage, eosinophil (Eo), and mixed colonies as well as megakaryocytes from human bone marrow cells. rh IL-3 was a weaker stimulus than rh granulocyte-macrophage colony-stimulating factor (GM- CSF) for day 14 myeloid cell colonies. At day 7 of incubation, rh IL-3 stimulated a few G, M, and Eo clusters but no colonies. This loss of responsiveness of myeloid cells to rh IL-3 was accentuated with further differentiation of the cells. rh IL-3 stimulated very few or no clones after five-day incubation with enriched promyelocytes and myelocytes, whereas rh GM-CSF was an efficient stimulus. Responsiveness to rh IL-3 was completely lost in postmitotic mature neutrophils. Incubation of these cells with rh IL-3 did not result in enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) of tumor cells or superoxide anion production after stimulation with formyl-methyl-leucyl-phenylalanine (FMLP), although they could be stimulated by rh GM-CSF. In addition, preincubation of neutrophils with different concentrations of rh IL-3 failed to increase or decrease their response to rh GM-CSF. In contrast to neutrophils, mature Eos could be stimulated by rh IL-3 to kill antibody-coated tumor cells. These results show that cells of the neutrophilic myeloid series lose their responsiveness to h IL-3 as they differentiate and suggest that although h IL-3 may be an important therapeutic agent to use for hematopoietic regeneration in vivo, the lack of stimulation of mature neutrophil function makes it an unlikely sole candidate as adjunct therapy for treatment of infectious diseases.