Télomères monofonctionnels du chlorure de vinyle, 3. Cinétique par catalyse rédox

A kinetic study of the redox telomerization of vinyl chloride with carbon tetrachloride was carried out. Transfer constants of PVC to the metallic ion (C_Feⁿ), initiation rate (k_i), and functionnality of the resulting telomers were measured. Instantaneous and cumulated polymerization degrees, (DP_n )_i and (DP_n )_cum were determined with the help of a theoretical study. These constants provide a rigorous control of the telomerization of vinyl chloride with RCCl₃, (R containing an alcohol or ester group).     

Relationship between ROS production, apoptosis and DNA denaturation in spermatozoa from patients examined for infertility

BACKGROUND: The aim of this study was to examine the role of apoptosis and reactive oxygen species (ROS) in inducing DNA damage in ejaculated spermatozoa. METHODS: We examined ejaculated spermatozoa from 31 patients examined for infertility and 19 healthy donors for apoptosis, production of ROS and DNA damage using annexin V binding, chemiluminescence assay and sperm chromatin structure assay. RESULTS: The percentage of spermatozoa that underwent apoptosis in the whole ejaculate and mature fraction was higher in the patients than in the donors (P<0.001 and P=0.009, respectively). Levels of ROS in the whole ejaculate and immature fraction were higher in the patients than in the donors (P=0.002 and P=0.009). Apoptosis was significantly correlated with ROS within patients in the whole ejaculate [r (95% confidence interval)=0.53 (0.19-0.86)] and in the mature [0.71 (0.39-1.00)] and immature spermatozoa [0.75 (0.45-1.00)]. Only apoptosis and the DNA fragmentation index (DFI) were significantly correlated within patients in the whole ejaculate [0.57 (0.18-0.97)]. CONCLUSIONS: DNA damage may be induced by oxidative assault. Apoptosis may not contribute significantly to the DNA damage.     

Genetic susceptibility to visceral leishmaniasis in The Sudan: linkage and association with IL4 and IFNGR1

Longitudinal studies in Sudan show ethnic differences in incidence and clinical phenotypes associated with Leishmania donovani. Immunologically, bias in type 1 vs type 2 cytokine responses is important. To determine whether polymorphisms at IL4/IL9 or IFNGR1 contribute to susceptibility, we examined 59 multicase families of visceral leishmaniasis (VL) with/without post Kala-azar dermal leishmaniasis (PKDL). Multipoint nonparametric analysis (Allegro) linked IL4/IL9 to VL per se (P=0.002). Transmission disequilibrium testing with robust variance estimates confirmed association in the presence of linkage between VL per se and IL4 (P=0.008) but not IL9. Stepwise logistic regression analysis showed both IL4RP2 and IL4RP1 markers contributed significantly to the association, suggesting a common disease-associated haplotype. In contrast, IFNGR1 was linked (P=0.031) and associated (P=0.007) to PKDL but not VL or VL per se. Hence, polymorphism in a type 2 cytokine gene influences underlying susceptibility to VL, whereas IFNGR1 is specifically related to susceptibility to PKDL.     

Characterization of Non-Hodgkin''s Lymphomas Using Multiple Cell Markers: Immunologic, Morphologic, and Cytochemical Studies of 72 Cases

Tissues from 72 cases (87 specimens) of various non-Hodgkin's lymphomas were analyzed for cell markers using multiple techniques. Cell suspensions were evaluated for E, EAC, and IgGEA rosette forming cells; Fc receptor cells; and surface immunoglobulin bearing cells. Cryostat section studies topographically defined EAC binding cells. Cytochemical determinations and immunoperoxidase methods for detection of intracellular immunoglobulin and lysozyme complemented other techniques in evaluating infiltrates containing large neoplastic cells. B-cell malignancies comprised 58 cases (80%) of this series and included well and moderately well differentiated lymphocytic lymphomas (10/10); nodular (23/23) and diffuse (10/18) poorly differentiated lymphocytic lymphomas; and lymphomas of mixed lymphocytic-“histiocytic” (3/3), “undifferentiated” (3/3), and “histiocytic” (9/13) types. Nodular lymphomas were characterized as B-cell neoplasms but also revealed a prominent population of T lymphocytes (39 ± 12%). Alkaline phosphatase activity, a cytochemical marker for lymphoid cells of follicular cuffs, was most consistently observed in B-cell lymphomas of moderately well differentiated lymphocytic type (4/6 cases). In some diffuse lymphomas, cryostat section studies (EAC rosettes) suggested a pre-existing nodular proliferation. One unusual B-cell lymphoma of large cell type exhibited IgGEA rosette formation and a strong receptor for the Fc portion of IgG. Ten lymphomas (14%) were of T-cell type and were represented by cases of diffuse poorly differentiated lymphocytic lymphoma (5/18, including 3 lymphoblastic lymphomas), Sézary syndrome (1), mycosis fungoides (1), and a cytologically distinctive large cell (“histiocytic”) lymphoma (3/13). Acid phosphatase activity was a consistent marker for the T-cell malignancies, some of which also revealed α-naphthyl butyrate esterase activity. No true histiocytic lymphomas were detected. Three cases of diffuse poorly differentiated lymphocytic lymphoma and one “histiocytic” lymphoma were null.     

Favorably tipping the balance between cytopathic and regulatory T cells to create transplantation tolerance

Therapeutic application of broadly reactive anti-T cell antibodies can lead not only to potent immunosuppression but also to profound and long-lived T cell depletion. We reasoned that a strategy that almost exclusively targets activated cytopathic donor reactive T cells and spares immunoregulatory networks might prove to be an exceptionally potent and highly selective means of producing long-term engraftment and tolerance. Herein we show that the combined administration of rapamycin and agonist IL-2- and antagonist IL-15-related cytolytic fusion proteins provides for long-term engraftment/tolerance in exceptionally stringent allotransplant models by (1) limiting the early expansion of activated T cells, (2) preserving and even exaggerating their subsequent apoptotic clearance, and (3) further amplifying the depletion of these activated T cells by antibody-dependent mechanisms, while (4) preserving CD4+CD25+ T cell-dependent immunoregulatory networks.     

Sequential synthesis and secretion of pectinases by Penicillium frequentans

Penicillium frequentans synthesized eleven polygalacturonases and three pectinesterases when grown in the presence of pectin, sodium polypectate or monogalacturonic acid. When glucose was the sole carbohydrate source in the medium two of these polygalacturonases and one pectinesterase were produced. The enzymes produced under any of these conditions degraded pectic substrates to monogalacturonic acid, suggesting that this monosaccharide or its metabolites should induce the pectinolytic complex. All pectinesterases and most of the extracellular polygalacturonases were synthesized after the 2nd hour of incubation. The pectinases produced by Penicillium frequentans were not secreted at the same time but after 5 hours of incubation all of them could be detected outside the cell those detected only inside the cell were probably membrane-associated or unglycosylated forms of the extracellular pectinases.     

TLR8 and TLR7 are involved in the host's immune response to human parechovirus 1

Toll-like receptors (TLR) have a key role in regulating immunity against microbial agents. Engagement of TLR by bacterial, viral or fungal components leads to the production and release of inflammatory cytokines. In this study we show that mainly TLR8 and also TLR7 act as the host sensors for human parechovirus 1, a single-stranded RNA (ssRNA) virus. Furthermore, we see that the viral ssRNA genome is detected in endosomal compartments by these TLR, which activate signalling that lead to the synthesis of pro-inflammatory molecules by the host.