Histopathological studies ofSporothrix schenckii-inoculated mice

Defense mechanisms againstSporothrix schenckii were studied using mouse models. After an intracutaneous injection of the yeast form ofS. schenckii to the dorsal skin of the congenitally athymic nude and normal heterozygote littermate mice, nodules were formed. They regressed and disappeared in 10 weeks in the case of normal mice. On the other hand, nodules and then ulceration developed progressively in nude mice until all animals expired by dissemination of microorganisms at the 11th week of inoculation. Histopathologically the migrated cells were similar in both the normal and the nude mice, particularly during the early phase (within 24 h), with infiltration by PMNs being predominant. Fragmentation ofS. schenckii commenced early during the 12–24 h stage of inoculation in the normal mice, while such fragmentation was scarce in nude mice even though numerous PMNs accumulated. Microscopic observations in the early stages (within 24 h of inoculation) suggested that the lack of killing activity by PMNs in nude mice contributes more to the impaired defense than the lack of macrophage activation by T-cells.     

Les génotypes responsables de mucoviscidose ou d’absence bilatérale des canaux déférents ABCD

Over the last decade, the genetic basis for CBAVD has been identified by its association with CFTR gene mutations, and CBAVD is now generally considered to be a mild or incomplete form of CF. In this review, the author summarizes the main results of compilation of CFTR gene analysis conducted in French laboratories for 3,923 patients with CF and 800 males with CABVD. The degree of clinical expression can be affected by several variables, including the molecular mechanisms by which the various CFTR mutations impair or disrupt the function of the CFTR chloride channel. Phenotypic expression of CFTR mutational genotypes varies from severe, progressive pulmonary disease with pancreatic insufficiency (CF-PI), to mild pulmonary disease with pancreatic sufficiency (PS) or singleorgan forms of “CFTR-opathies”. In CF, a total of 310 different CFTR mutations accounting for 94% of 7,846 CF alleles have generated almost 500 different genotypes, comprising 2 severe mutations in 88% of cases (CF-PI), one severe mutation in trans to a mild mutation in 11% (CF-PS), and 2 mild mutations in 1% of identified genotypes. In CBAVD, 137 mutations scattered over the whole gene were identified in 60% of 1,600 CBAVD alleles during the study. Among the 150 characterized mutational CFTR genotypes, compound heterozygosity was the rule, and the most frequent CBAVD combinations were ΔF508/5T (35%), ΔF508/other mutation (30%, including ΔF508/R117H-7T: 5,6%), and 5T/other mutation (17%). No combination of two severe mutations was found in CBAVD (0%); by contrast with the CF population, 88% of genotypes identified in CBAVD comprised a severe mutation in trans to a mild mutation, and 12% consisted of 2 mild mutations. A total of 22 genotypes were shared by both CF and CBAVD. The role of the 5T allele as a splicing variant with variable, incomplete disease penetrance in CBAVD is reviewed. Other haplotype backgrounds, such as the TG12 sequence and the M470V polymorphism, may influence CFTR splicing and/or function. This study confirms the high molecular heterogeneity of CFTR mutations in CBAVD and emphasizes the importance of extensive CFTR analysis in these patients. Longterm follow-up studies of CBAVD patients are necessary in order to predict the phenotypic consequences of numerous CFTR mutational genotypes.     

Continuous measurement of changes in intracellular calcium concentration in mouse splenic T cells attached to a glass substrate

Mitogen- and isoproterenol-induced changes of [Ca²⁺]_i in T cells attached to a glass substrate were examined. Murine (C57BL/6) splenic T cells were attached to coverslips or 35-mm dishes (MatTek) precoated with Cell Tak® (3.5 µg/cm²). The cells were then loaded with fluorescent dye (2 µg/ml of fura2-AM or fluo3-AM) and changes in [Ca²⁺]_i in a population of cells (using a spectrofluorometer) or in single cells (using a confocal microscope) were measured during continuous superfusion. Population measurements of [Ca²⁺]_i demonstrated that concanavalin A (Con A, 2 or 5 µg/ml) caused an increase in [Ca²⁺]_i that rose to a peak and then declined to a steady state. The concentration-response relationship (0.05–5 µg/ml) had an EC₅₀ of 0.3 µg/ml. Isoproterenol decreased the Con A-induced elevation of steady state [Ca²⁺]_i. In single cell studies, the increase in [Ca²⁺]_i in response to Con A typically occurred in about 50% of the cells in a microscope field, and the delay before activation varied among cells. Taken together, these data demonstrate that Cell Tak® can be used to attach T cells to glass coverslips and will be useful for the study of signaling mechanisms in T cells.     

Serum cytokine levels in patients with acute brucellosis and their relation to the traditional inflammatory markers

The number of clinical studies on gamma interferon (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and interleukin-4 (IL-4) in human brucellosis is limited. The present study was focused on IFN-gamma, TNF-alpha and IL-4 levels in acute brucellosis cases, in the acute phase and at the end of the treatment. The relation of these cytokines to traditional inflammation markers was also investigated. The study included 27 cases of acute brucellosis and 20 healthy volunteers who had no complaints. It was found that mean IFN-gamma and TNF-alpha levels, CRP (C-reactive protein) levels and ESR (erythrocyte sedimentation rate) values were significantly higher in acute brucellosis cases as compared to post-treatment values and values measured in the control group. In addition, IFN-gamma and TNF-alpha levels measured in the acute phase correlated with the increase in CRP levels and ESR values. Our results confirmed that IFN-gamma and TNF-alpha are involved in the pathophysiology of brucellosis and are closely related to the inflammatory activation of the disease. In view of the present findings, it is suggested that IFN-gamma and TNFalpha may be used for monitoring brucellosis.     

Failure of neutralizing gp120 monoclonal antibodies to prevent HIV infection of choriocarcinoma-derived trophoblasts

Although placental trophoblasts, the only fetal cells in direct contact with infectious maternal blood, can be infected with HIV, the precise cause for the low transmission rate of virus across the placental barrier is unknown. One of the most common conjectures is that maternal anti-HIV antibodies (Abs) contribute to the protection of the fetus. This hypothesis has been tested in vitro by infecting the CD4-negative placental trophoblast line, BeWo, with HIV-1_IIIB in the presence of serial dilutions of neutralizing monoclonal Abs against the V3 loop (No. 694) or CD4-binding conformational domain (No. 588). The results, based on measurement of p24 production from virus-exposed cells, reveal that the titers of Abs, adequate in preventing the infection of control MT-4 T lymphocytes, were less effective in protecting trophoblasts. Furthermore, PCR analysis of HIV DNA formed after a single round of infection has shown no significant decrease in the number of viral copies in Ab-protected BeWo cells. An anti-HIV serum from a pregnant woman did also have no effect. Although our in vitro observations do not necessarily apply to the in vivo situation, the results suggest that the humoral immune response sustained by neutralizing Abs may be able to protect T lymphocytes, but not placental trophoblasts. The findings are consistent with recent clinical studies demonstrating a lack of correlation between the presence of neutralizing anti-HIV Abs in pregnant women and HIV transmission in utero.     

Molecular cloning of ATR5(Emoy2) from Hyaloperonospora arabidopsidis, an avirulence determinant that triggers RPP5-mediated defense in Arabidopsis

RPP5 is the seminal example of a cytoplasmic NB-LRR receptor-like protein that confers downy mildew resistance in Arabidopsis thaliana. In this study, we describe the cloning and molecular characterization of the gene encoding ATR5(Emoy2), an avirulence protein from the downy mildew pathogen Hyaloperonospora arabidopsidis isolate Emoy2. ATR5(Emoy2) triggers defense response in host lines expressing the functional RPP5 allele from Landsberg erecta (Ler-0). ATR5(Emoy2) is embedded in a cluster with two additional ATR5-like (ATR5L) genes, most likely resulting from gene duplications. ATR5L proteins do not trigger RPP5-mediated resistance and the copy number of ATR5L genes varies among H. arabidopsidis isolates. ATR5(Emoy2) and ATR5L proteins contain a signal peptide, canonical EER motif, and an RGD motif. However, they lack the canonical translocation motif RXLR, which characterizes most oomycete effectors identified so far. The signal peptide and the N-terminal regions including the EER motif of ATR5(Emoy2) are not required to trigger an RPP5-dependent immune response. Bioinformatics screen of H. arabidopsidis Emoy2 genome revealed the presence of 173 open reading frames that potentially encode for secreted proteins similar to ATR5(Emoy2), in which they share some motifs such as EER but there is no canonical RXLR motif.     

Reverse Relationship Between Blood Boron Level and Body Mass Index in Humans: Does It Matter for Obesity?

The exact role of boron in humans is not known although its supplementation causes several important metabolic and inflammatory changes. The objective of this study is to evaluate the possibility of an association between blood boron level and obesity in normal, overweight, obese, and morbidly obese subjects. A total number of 80 subjects, categorized into four groups based on their body mass index as normal, overweight, obese, and morbidly obese, were enrolled in this study. Age, sex, body mass index, and blood boron levels were recorded for each subject. Although the distribution of female and male subjects and blood boron levels were similar between groups, the mean age of normal subjects was significantly lower than the others (p?=?0.002). There was a significant relationship between age and quantitative values of body mass index for each subject (β?=?0.24; p?=?0.003). In addition, between blood boron levels and quantitative values of body mass index for each subject, a significant reverse relationship was detected (β?=??0.16; p?=?0.043). Although age seemed to be an important variable for blood boron level and body mass index, blood boron levels were shown to be lower in obese subjects in comparison to non-obese subjects.