Computational and Empirical Trans-hydrogen Bond Deuterium Isotope Shifts Suggest that N1–N3 A:U Hydrogen Bonds of RNA are Shorter than those of A:T Hydrogen Bonds of DNA

Density functional theory calculations of isolated Watson–Crick A:U and A:T base pairs predict that adenine ¹³C2 trans-hydrogen bond deuterium isotope shifts due to isotopic substitution at the pyrimidine H3, ^2hΔ¹³C2, are sensitive to the hydrogen-bond distance between the N1 of adenine and the N3 of uracil or thymine, which supports the notion that ^2hΔ¹³C2 is sensitive to hydrogen-bond strength. Calculated ^2hΔ¹³C2 values at a given N1–N3 distance are the same for isolated A:U and A:T base pairs. Replacing uridine residues in RNA with 5-methyl uridine and substituting deoxythymidines in DNA with deoxyuridines do not statistically shift empirical ^2hΔ¹³C2 values. Thus, we show experimentally and computationally that the C7 methyl group of thymine has no measurable affect on ^2hΔ¹³C2 values. Furthermore, ^2hΔ¹³C2 values of modified and unmodified RNA are more negative than those of modified and unmodified DNA, which supports our hypothesis that RNA hydrogen bonds are stronger than those of DNA. It is also shown here that ^2hΔ¹³C2 is context dependent and that this dependence is similar for RNA and DNA. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

High frequency of skin reactions in patients with leishmaniasis treated with meglumine antimoniate contaminated with heavy metals: a comparative approach using historical controls

We analyzed data from historical controls treated with meglumine antimoniate to compare the frequency of adverse events observed in patients with cutaneous leishmaniasis treated with the same dose of meglumine antimoniate contaminated with heavy metals in an endemic area of the State of Bahia, Brazil. Group A patients were treated in 2000 with the drug produced by Eurofarma Laborat rios Ltda., S o Paulo, Brazil (lot A) and group B patients were treated in 1996 with the reference drug produced by Rhodia Farma Ltda., S o Paulo, Brazil (lot B). We observed an unusual higher frequency of skin reactions in group A patients. However, all type of adverse events observed in group A were also observed in group B. The physico-chemical analysis of these lots revealed that lot A had lower pH and higher concentration of total and trivalent antimony, lead, cadmium, and arsenic. Our findings suggest that the skin reactions could be attributed to heavy metal contamination of lot A.     

In vitro SAR of pyrrolidine-containing histamine H3 receptor antagonists: trends across multiple chemical series

Structure-activity relationships (SAR) were analyzed within a library of diverse yet simple compounds prepared as histamine H3 antagonists. The libraries were constructed with a variety of low molecular weight pyrrolidines, selected from (R)-2-methylpyrrolidine, (S)-2-methylpyrrolidine, and pyrrolidine.     

CC chemokine receptor 2 expression in donor cells serves an essential role in graft-versus-host-disease

The complete repertoire of cellular and molecular determinants that influence graft-vs-host disease (GVHD) is not known. Using a well-established murine model of GVHD (B6-->bm12 mice), we sought to elucidate the role of the donor non-T cell compartment and molecular determinants therein in the pathogenesis of GVHD. In this model the acute GVHD-inducing effects of purified B6 wild-type (wt) CD4(+) T cells was inhibited by wt non-T cells in a dose-dependent manner. Paradoxically, unlike the chronic GVHD phenotype observed in bm12 mice transplanted with B6wt unfractionated splenocytes, bm12 recipients of B6ccr2-null unfractionated splenocytes developed acute GVHD and died of IFN-gamma-mediated bone marrow aplasia. This switch from chronic to acute GVHD was associated with increased target organ infiltration of activated CD4(+) T cells as well as enhanced expression of Th1/Th2 cytokines, chemokines, and the antiapoptotic factor bfl1. In vitro, ccr2(-/-) CD4(+) T cells in unfractionated splenocytes underwent significantly less activation-induced cell death than B6wt CD4(+) T cells, providing another potential mechanistic basis along with enhanced expression of bfl1 for the increased numbers of activated T cells in target organs of B6ccr2(-/-) splenocyte-->bm12 mice. Collectively, these findings have important clinical implications, as they implicate the donor non-T cell compartment as a critical regulator of GVHD and suggest that ccr2 expression in this cellular compartment may be an important molecular determinant of activation-induced cell death and GVHD pathogenesis.     

S100A9 Induced Inflammatory Responses Are Mediated by Distinct Damage Associated Molecular Patterns (DAMP) Receptors In Vitro and In Vivo

Release of endogenous damage associated molecular patterns (DAMPs), including members of the S100 family, are associated with infection, cellular stress, tissue damage and cancer. The extracellular functions of this family of calcium binding proteins, particularly S100A8, S100A9 and S100A12, are being delineated. They appear to mediate their functions via receptor for advanced glycation endproducts (RAGE) or TLR4, but there remains considerable uncertainty over the relative physiological roles of these DAMPs and their pattern recognition receptors. In this study, we surveyed the capacity of S100 proteins to induce proinflammatory cytokines and cell migration, and the contribution RAGE and TLR4 to mediate these responses in vitro. Using adenoviral delivery of murine S100A9, we also examined the potential for S100A9 homodimers to trigger lung inflammation in vivo. S100A8, S100A9 and S100A12, but not the S100A8/A9 heterodimer, induced modest levels of TLR4-mediated cytokine production from human PBMC. In contrast, for most S100s including S100A9, RAGE blockade inhibited S100-mediated cell migration of THP1 cells and major leukocyte populations, whereas TLR4-blockade had no effect. Intranasal administration of murine S100A9 adenovirus induced a specific, time-dependent predominately macrophage infiltration that coincided with elevated S100A9 levels and proinflammatory cytokines in the BAL fluid. Inflammatory cytokines were markedly ablated in the TLR4-defective mice, but unexpectedly the loss of TLR4 signaling or RAGE-deficiency did not appreciably impact the S100A9-mediated lung pathology or the inflammatory cell infiltrate in the alveolar space. These data demonstrate that physiological levels of S100A9 homodimers can trigger an inflammatory response in vivo, and despite the capacity of RAGE and TLR4 blockade to inhibit responses in vitro, the response is predominately independent of both these receptors.     

Overexpression of manganese superoxide dismutase does not increase clonogenic cell survival despite effect on apoptosis in irradiated lymphoblastoid cells

Gene therapy-mediated overexpression of superoxide dismutases (SOD) appears to be a promising strategy for modulating radiosensitivity based on detoxification of superoxide radicals and suppression of apoptosis. Using recombinant lentiviral-based vectors, the effects of SOD overexpression on both were tested in human lymphoblastoid cells (TK6) that are sensitive to radiation-induced apoptosis. TK6 cells were transduced with vectors containing CuZnSOD, MnSOD or inverted MnSOD (MSODi) cDNA. Gene transfer efficiency, SOD activity, superoxide-radical resistance, apoptosis and clonogenic survival were determined. A six- to eightfold increase in SOD activity was observed after transduction, rendering MnSOD-overexpressing TK6 cells significantly more resistant to paraquat-induced superoxide radical production than controls. Although significant differences in sensitivity to apoptosis were observed for MnSOD, no differences in clonogenic survival after irradiation were detected between any groups. Our data show that efficient cellular SOD overexpression, an increased superoxide radical detoxifying ability and, for MnSOD, decreased apoptosis did not result in increased clonogenic survival after irradiation. This strengthens the hypothesis of differences in the radiation-modulating effects of SOD on normal and malignant cells (protective and nonprotective, respectively), thereby showing its potential to increase the therapeutic index in future clinical SOD-based radioprotection approaches.