Leptospirosis in Reunion Island (Indian Ocean): analysis of factors associated with severity in 147 confirmed cases

Objective Analysis of risk factors associated with severity in patients with confirmed leptospirosis. Design and setting Retrospective study in 147 leptospirosis-confirmed patients at two tertiary nonteaching hospital in Reunion Island. Patients 138 men and 9 women, aged 36 ± 14 years, 80 in the ICU and 67 in medical wards. Measurements and results We collected demographic, clinical, biological, and radiographic data and performed univariate and multivariate analysis to examine risk factors associated with admission in ICU and mortality. Pulmonary forms were more frequent (85%) than in previous reports, with 85 cases (65.3%) on abnormal chest radiography. Among the 38 patients who underwent bronchoalveolar lavage at admission 31 (81.5%) had alveolar hemorrhage. Independent factors related to ICU admission were: age over 46 years (OR 3.02), creatinine higher than 200 μmol/l (6.69), shock (13.87), and acute respiratory failure (20.69). Mortality was 12.9%. The only factor independently related to mortality was need for mechanical ventilation (OR 20.94). Icterohemorrhagiae serogroup was found in 62 cases (42.8%) but was not related to death. Conclusions Pulmonary involvement is a major feature in leptospirosis disease but is not associated with poor outcome. Identification of clinical and laboratory findings on admission may help to better characterize severe cases. Mailing address: Arnaud Bourdin is currently at the Service de Pneumologie, CHU Montpellier, France.     

Contribution of magnetic resonance spectrometry to the diagnosis of intracranial tumors

Magnetic resonance spectroscopy (MRS) is a method enabling the analysis of the tissue metabolic content. It may offer a more accurate diagnosis of the intracranial tumors than conventional MRI sequences. MRS of normal brain parenchyma displays 4 main metabolites: N-acetyl aspartate (neuronal marker), creatine (cellular density marker), choline (membrane activity marker) and myoinositol (glial marker); pathological processes lead to variations of the level of these metabolites and/or the appearance of abnormal metabolites (lactate), following different patterns according to pathological process involved: glioma, meningioma, metastasis, bacterial or toxoplasmic abscess, radionecrosis. The potential clinical use of this method includes positive, differential and etiological diagnosis of tumors, determination of the level of malignancy of gliomas, screening for tumor recurrence following treatment. Our laboratory has been performing MR spectroscopic explorations of brain tumors for many years. Based on this experience, we show how MRS can be routinely performed in the clinical setting, what are its limitations and potential, and what kind of information can be supplied to the clinician.     

Drug specific cytotoxic T-cells in the skin lesions of a patient with toxic epidermal necrolysis

Toxic epidermal necrolysis is an extremely severe drug reaction, manifesting itself by widespread apoptosis of keratinocytes, generally considered to result from Fas/CD95-FasLigand interaction, but of unknown primary mechanism. We looked at the role of cells present in the skin blisters as probable effectors of this immune reaction. In a patient suffering from cotrimoxazole-induced toxic epidermal necrolysis, blister fluid cells were phenotyped by FACS and tested without prior restimulation for cytotoxicity on autologous and allogeneic cells in the presence of the drug. Blister fluid lymphocytes were predominantly CD8+, DR+, CLA+, CD56+ T lymphocytes, perforin positive and expressing preferentially two Vbeta chains of the T cell receptor repertoire. These lymphocytes were cytotoxic only in the presence of the drug towards autologous EBV transformed lymphocytes and towards allogeneic cells sharing HLA-Cw4. Cytotoxicity occurred in the presence of either cotrimoxazole, sulfamethoxazole, or the nitroso metabolite of sulfamethoxazole, but not with the hydroxylamine metabolite of sulfamethoxazole. The lysis was blocked by an anti-MHC class I monoclonal antibody. It was abolished by EGTA and CMA, but neither by anti-fas, brefeldin A, nor by anti-TRAIL receptor monoclonal antibodies, strongly suggesting perforin/granzyme-mediated cytotoxicity, without implication of Fas or TRAIL at this stage. This is direct evidence that T lymphocytes present within the lesions of toxic epidermal necrolysis may exhibit, without any re-stimulation, a drug-specific cytotoxicity against autologous cells. Harboring the markers of classical CTL and MHC class I restriction these lymphocytes reacted against the parent drug and one of its reactive metabolites. These results challenge several current concepts and could support new therapeutic approaches.     

Chromosome and gene copy number variation allow major structural change between species and strains of Leishmania

Leishmania parasites cause a spectrum of clinical pathology in humans ranging from disfiguring cutaneous lesions to fatal visceral leishmaniasis. We have generated a reference genome for Leishmania mexicana and refined the reference genomes for Leishmania major, Leishmania infantum, and Leishmania braziliensis. This has allowed the identification of a remarkably low number of genes or paralog groups (2, 14, 19, and 67, respectively) unique to one species. These were found to be conserved in additional isolates of the same species. We have predicted allelic variation and find that in these isolates, L. major and L. infantum have a surprisingly low number of predicted heterozygous SNPs compared with L. braziliensis and L. mexicana. We used short read coverage to infer ploidy and gene copy numbers, identifying large copy number variations between species, with 200 tandem gene arrays in L. major and 132 in L. mexicana. Chromosome copy number also varied significantly between species, with nine supernumerary chromosomes in L. infantum, four in L. mexicana, two in L. braziliensis, and one in L. major. A significant bias against gene arrays on supernumerary chromosomes was shown to exist, indicating that duplication events occur more frequently on disomic chromosomes. Taken together, our data demonstrate that there is little variation in unique gene content across Leishmania species, but large-scale genetic heterogeneity can result through gene amplification on disomic chromosomes and variation in chromosome number. Increased gene copy number due to chromosome amplification may contribute to alterations in gene expression in response to environmental conditions in the host, providing a genetic basis for disease tropism.     

Intracellular pH regulates amyloid precursor protein intracellular domain accumulation

The amyloid precursor protein (APP) metabolism is central to pathogenesis of Alzheimer's disease (AD). Parenchymal amyloid deposits, a neuropathological hallmark of AD, are composed of amyloid-beta peptides (Abeta). Abeta derives from the amyloid precursor protein (APP) by sequential cleavages by beta- and gamma-secretases. Gamma-secretase cleavage releases the APP intracellular domain (AICD), suggested to mediate a nuclear signaling. Physiologically, AICD is seldom detected and thus supposed to be rapidly degraded. The mechanisms responsible of its degradation remain unknown. We used a pharmacological approach and showed that several alkalizing drugs induce the accumulation of AICD in neuroblastoma SY5Y cell lines stably expressing APP constructs. Moreover, alkalizing drugs induce AICD accumulation in naive SY5Y, HEK and COS cells. This accumulation is not mediated by the proteasome or metallopeptidases and is not the result of an increased gamma-secretase activity since the gamma-secretase cleavage of Notch1 and N-Cadherin is not affected by alkalizing drug treatments. Altogether, our data demonstrate for the first time that alkalizing drugs induce the accumulation of AICD, a mechanism likely mediated by the endosome/lysosome pathway.     

Optimization of power wheelchair control for patients with severe Duchenne muscular dystrophy

The extended survival of patients with Duchenne muscular dystrophy (DMD) achieved by the introduction of mechanical ventilation is raising new quality-of-life issues. We evaluated passive range of wrist extension, key pinch strength, and power wheelchair driving in 84 patients. The 47 drivers with restricted driving abilities were older than the 37 unrestricted drivers (27.2+/-5.0 y vs. 22.8+/-3.8 y) and had worse upper limb performance. By multiple logistic regression, only key pinch was significant ( R(2) = 0.224, P = 0.02. Eighteen restricted drivers were reassessed after having swapped a conventional joystick for another control system (mini-joystick, isometric mini-joystick, finger joystick, or pad) and having moved the position of the tested control system so that the patient could use it with different fingers, his chin or his mouth. All of them regained the ability to drive unrestricted. Adults with DMD gradually lose their ability to drive with a conventional joystick but can regain unrestricted driving with alternative control systems.     

Spatial Distribution and Burden of Emerging Arboviruses in French Guiana

Despite the health, social and economic impact of arboviruses in French Guiana, very little is known about the extent to which infection burden is shared between individuals. We conducted a large multiplexed serological survey among 2697 individuals from June to October 2017. All serum samples were tested for IgG antibodies against DENV, CHIKV, ZIKV and MAYV using a recombinant antigen-based microsphere immunoassay with a subset further evaluated through anti-ZIKV microneutralization tests. The overall DENV seroprevalence was estimated at 73.1% (70.6–75.4) in the whole territory with estimations by serotype at 68.9% for DENV-1, 38.8% for DENV-2, 42.3% for DENV-3, and 56.1% for DENV-4. The overall seroprevalence of CHIKV, ZIKV and MAYV antibodies was 20.3% (17.7–23.1), 23.3% (20.9–25.9) and 3.3% (2.7–4.1), respectively. We provide a consistent overview of the burden of emerging arboviruses in French Guiana, with useful findings for risk mapping, future prevention and control programs. The majority of the population remains susceptible to CHIKV and ZIKV, which could potentially facilitate the risk of further re-emergences. Our results underscore the need to strengthen MAYV surveillance in order to rapidly detect any substantial changes in MAYV circulation patterns.