Synergistic role of CD4+ and CD8+ T lymphocytes in IFN-gamma production and protective immunity induced by an attenuated Toxoplasma gondii vaccine.

BALB/c mice vaccinated with a temperature-sensitive mutant (TS-4) of Toxoplasma gondii develop complete resistance to lethal challenge with a highly virulent toxoplasma strain (RH). This immunity is known to be dependent on IFN-gamma synthesis. In vitro and in vivo T cell depletions were performed in order to identify the subsets responsible for both protective immunity and IFN-gamma production. When stimulated with crude tachyzoite Ag in vitro, CD4+ cells from vaccinated mice produced high levels of TH1 cytokines (IL-2 and IFN-gamma) but not TH2 cytokines (IL-4 and IL-5). CD8+ cells, in contrast, produced less IFN-gamma and no detectable IL-2. Nevertheless, they could be induced to synthesize IFN-gamma when exposed in culture to exogenous IL-2. In vivo treatment with anti-CD4 plus anti-CD8 or anti-IFN-gamma antibodies during challenge infection completely abrogated resistance to T. gondii. In contrast, treatment with anti-CD4 alone failed to reduce immunity, whereas anti-CD8 treatment partially decreased vaccine-induced resistance. These results suggest that although IFN-gamma and IL-2-producing CD4+ lymphocytes are induced by vaccination, IFN-gamma-producing CD8+ T cells are the major effectors of immunity in vivo. Nevertheless, CD4+ lymphocytes appear to play a synergistic role in vaccine-induced immunity, probably through the augmentation of IFN-gamma synthesis by the CD8+ effector cells. This hypothesis is supported by the observation that when giving during vaccination, as opposed to after challenge, anti-CD4 antibodies are capable of blocking protective immunity.     

Regulation of plasma membrane Ca2+ ATPases by lipids of the phosphatidylinositol cycle

When the erythrocyte plasma membrane Ca2+ pump is reconstituted into phosphatidylcholine liposomes, the inclusion of small amounts of phosphatidic acid or phosphatidylinositol 4,5-bisphosphate stimulates the enzyme's activity. Other lipids of the phosphatidylinositol cycle (diacylglycerol, phosphatidylinositol) have little effect. The stimulatory effect of phosphatidylinositol 4,5-bisphosphate is greater than that of calmodulin; this lipid also stimulates the plasma membrane Ca2+ ATPase from rat brain.     

Retentissement de l’infection genitale a chlamydia trachomatis sur le sperme chez les hommes consultant pour infertilite du couple

Chlamydia trachomatis (CT) genital infection is one of the most frequent causes of infertility. Its repercution on semen parameters and male infertility is controversial. The objective of this study was to evaluate the impact of CT genital infection on semen parameters in male partners of infertile couples. Ninety-seven infertile couples were studied. Semen, urethral and cervical samples were tested for CT by means of direct fluorescence antibodies assay (DFA), cell culture, polymerase chain reaction (PCR) and FLISA. Sera from both parteners were tested for immunoglobulin M, A and G antibodies to Chlamydia by means of the microimmunofluorescence MIF). For all mens, standard semen parameters were analysed according to the guidlines of the word health organisation. CT infection was identified in 34% of the male partners. In 76% of cases, the infection was asymptomatic. 60,6% of infected patients’s wives were also infected by CT. There was no significant difference between the mean values of concentration, motility and morphology of spermatozoa in both groups of male patients, infected by CT (CT+ group) and lacked infection (CT-group). The mean values of motility, vitality, concentration and normal forms of spermatozoa, in both CT+ and CT- groups were respectively: 39,6%±17,5% vs 40,4% ± 14,9%, 61,9% ±18,1% vs 62,4% ± 18,5%, 80,7×10⁶±67,5×10⁶ vs 67,1×10⁶ ±65,2×10⁶ and 34,7% ± 16,7% vs 33% ± 0,1%. Oligospermia was significantly more frequent in CT+ group (54,9%) than in CT-group (26,9%). High levels of coiled flagella (≥20) were more frequently observed in CT+ group (18,5%) than in CT-group (7,4%), but the difference was not significant. We found in this study a high prevalence of genital chlamydial infection into infertile couples. This infection has no repercution on sperm quality, suggesting that there is no effect of CT upon the spermatozoa. But, we can not exclude any impact on fertilisation ability and/or ultrastructure of these gametes. The finding that oligospermia was more frequent in CT+group, leds us to suggest thas chlamydial infection has a repercution on the gametogenesis or on genital ducts permeability. Another hypothesis would be that oligospermia, reflect of spermatogenesis disorder would be associated with reduction of local immunity. Other studies with wide exploration of spermatic functions and of different parts of genital tract are needed to specify the real impact of genital chlamydial infection upon men reproduction function.     

Staurosporine, a protein kinase inhibitor, up-regulates the stimulation of human neutrophil respiratory burst by N-formyl peptides and platelet activating factor

Staurosporine (STAR), a potent protein kinase C (PKC) antagonist, was found to modulate the chemoattractant-induced respiratory burst of human polymorphonuclear leukocytes (PMNs) according to drug concentration. Low STAR concentrations from 10 to 200 nM potentiated the N-formyl-methionyl-leucyl-phenylalanine (fMLP) and platelet activating factor (Paf)-induced respiratory burst, affecting both the initial rate and the total amount of superoxide anion generated. The maximal increase occurred in the presence of 100 nM STAR and optimal fMLP concentration and reached 60-100% of control values. Above 250 nM, STAR inhibited the respiratory burst with an IC50 of 360 and 320 nM for fMLP and Paf, respectively. The respiratory burst induced by PKC activators such as phorbol myristate acetate or phorbol 12, 13 dibutyrate was inhibited effectively by STAR, with a low IC50 (25 nM) for both stimuli. Thus, the use of low STAR concentrations points to two possible roles of PKC in the regulation of NADPH oxidase activity, i.e. a positive regulation in phorbol ester-treated cells and a negative regulation in chemoattractant-stimulated PMNs.     

Plasma factor IX levels in patients given hexoestrol or stilboestrol to suppress lactation

A single injection of hexoestrol, 45 mg., is effective in suppressing lactation. Given in this way hexoestrol causes a small rise in plasma factor IX levels, of shorter duration than that produced by a customary and equally effective oral course of stilboestrol. With hexoestrol the plasma factor IX levels reverted to normal by the sixth day of the puerperium.     

Purification and properties of pig brain guanine deaminase.

Guanine deaminase (guanine aminohydrolase, EC 3.5.4.3) from pig brain was purified to homogeneity by column chromatography and ammonium sulphate fractionation. Homogeneity was established by polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulphate (SDS). The molecular weight of 110 000 was determined by gel filtration and sucrose density gradient centrifugation. SDS polyacrylamide gel electrophoresis indicated subunits of a molecular weight of 50 000. The amino acid composition, the isoelectric point and the number of -SH groups were determined. 5.5'-Dithiobis-(2-nitrobenzoic acid) reacts with about seven -SH groups in the native enzyme, but upon denaturation with SDS, 10 -SH groups react with this former reagent. Using electrolytic reduction, 44 half-cystines were determined in accordance with the number of cysteic acid residues determined by amino acid analysis after performic acid oxidation. The Km values determined for substrates of the enzyme were 1.1 . 10(-5) M for guanine in 0.1 M Tris. HCl buffer (pH 8.0) and 3.3 . 10(-4) M for 8-azaguanine in 0.1 M phosphate buffer, pH 6.4. The pKa values determined for ionizable groups of the active site of the enzyme were near pH 6.2 and pH 8.2. The chemical and kinetic evidence suggests that cysteine and histidine may be essential for the catalysis.     

Enhanced activity of hyperthermostable Pyrococcus horikoshii endoglucanase in superbase ionic liquids

Biotechnology Letters - Ionic liquids (ILs) that dissolve biomass are harmful to the enzymes that degrade lignocellulose. Enzyme hyperthermostability promotes a tolerance to ILs. Therefore, the...     

Animal models of Duchenne muscular dystrophy: from basic mechanisms to gene therapy

Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disorder. It is caused by loss-of-function mutations in the dystrophin gene. Currently, there is no cure. A highly promising therapeutic strategy is to replace or repair the defective dystrophin gene by gene therapy. Numerous animal models of DMD have been developed over the last 30 years, ranging from invertebrate to large mammalian models. mdx mice are the most commonly employed models in DMD research and have been used to lay the groundwork for DMD gene therapy. After ~30 years of development, the field has reached the stage at which the results in mdx mice can be validated and scaled-up in symptomatic large animals. The canine DMD (cDMD) model will be excellent for these studies. In this article, we review the animal models for DMD, the pros and cons of each model system, and the history and progress of preclinical DMD gene therapy research in the animal models. We also discuss the current and emerging challenges in this field and ways to address these challenges using animal models, in particular cDMD dogs.KEY WORDS: Duchenne muscular dystrophy, Dystrophin, Animal model, Canine DMD, Gene therapy