Vaccinia virus D10 protein has mRNA decapping activity, providing a mechanism for control of host and viral gene expression

Previous studies indicated that the vaccinia virus D10 protein, which is conserved in all sequenced poxviruses, participates in the rapid turnover of host and viral mRNAs. D10 contains a motif present in the family of Nudix/MutT enzymes, a subset of which has been shown to enhance mRNA turnover in eukaryotic cells through cleavage of the 5' cap (m7GpppNm-). Here, we demonstrate that a purified recombinant D10 fusion protein possesses an intrinsic activity that liberates m7GDP from capped RNA substrates. Furthermore, point mutations in the Nudix/MutT motif abolished decapping activity. D10 has a strong affinity for capped RNA substrates (Km approximately 3 nm). RNAs of 24-309 nt were decapped to comparable extents, whereas the cap of a 12-nt RNA was uncleaved. At large molar ratios relative to capped RNA substrate, competitor m7GpppG, m7GTP, or m7GDP inhibited decapping, whereas even higher concentrations of unmethylated analogs did not. High concentrations of uncapped RNA were also inhibitory, suggesting that D10 recognizes its substrate through interaction with both cap and RNA moieties. Thus far, poxviruses represent the only virus family shown to encode a Nudix hydrolase-decapping enzyme. Although it may seem self-destructive for a virus to encode a decapping and a capping enzyme, accelerated mRNA turnover helps eliminate competing host mRNAs and allows stage-specific synthesis of viral proteins.     

Evaluation of -2 RANTES vaginal microbicide formulations in a nonhuman primate simian/human immunodeficiency virus (SHIV) challenge model

A potential strategy to combat the worldwide AIDS epidemic is to develop a vaginal microbicide that prevents the sexual transmission of HIV-1. One approach for preventing vaginal HIV transmission is to block the viral coreceptor CCR5 with naturally occurring chemokine ligands. In this study, we used a cynomolgus macaque model to evaluate whether a variant of the CCR5 ligand RANTES (-2 RANTES), tested alone or in a nonphospholipid liposome carrier (Novasomes 7474), blocks vaginal challenge with a CCR5-tropic simian/human immunodeficiency virus (SHIV(162P3)). When tested in vitro, the synthetic chemokine potently inhibited SHIV(162P3) infection of cynomolgus macaque peripheral blood mononuclear cells (PBMC). Colposcopic examinations of treated animals and histological examination of cervicovaginal biopsies showed minimal signs of tissue inflammation following vaginal application of Novasomes 7474, -2 RANTES formulated in Novasomes 7474, or -2 RANTES alone. Following vaginal challenge with SHIV(162P3), complete protection was observed in four of six animals treated vaginally with -2 RANTES (0.13 mM) formulated in Novasomes 7474. However, the same proportion of animals was protected by treatment with Novasomes 7474 carrier alone. Two of five animals treated with 0.5 mM -2 RANTES in PBS were protected from infection. Further, all animals were infected when treated with lower chemokine concentrations. These findings indicate that natural CCR5 ligands may have limited efficacy in stringent nonhuman primate models for vaginal infection. In comparison, liposomal agents such as Novasomes 7474 provide comparatively robust protection against vaginal transmission.     

Nutrition concerns for the patient with gastroparesis

Gastroparesis is a debilitating disease that is the consequence of a variety of conditions resulting in a significant loss of quality of life. Although many cases are mild, some patients have protracted nausea and vomiting, making it difficult, if not impossible, to maintain their hydration and nutritional status. Furthermore, therapeutic levels of medications, such as prokinetic and antiemetic agents, can be difficult to achieve. The intent of this article is to provide the clinician with suggestions to improve the nutritional status of patients with gastroparesis and offer strategies to deal with the nutritional insults that arise in these unfortunate patients.     

Volume CT: state-of-the-art reporting

OBJECTIVE: CT has undergone generational change that has led to true volume imaging. Interpretation of volume images requires interaction between the radiologist and the volume data sets. The aim of this review is to examine postprocessing options and the evidence in the literature for changing the process of reporting to digital volume reporting. CONCLUSION: Diagnostic confidence and the accuracy of interpretation of volume CT images have increased with improvements in postprocessing techniques.     

A brain mechanism for facilitation of insight by positive affect

Previous research has shown that people solve insight or creative problems better when in a positive mood (assessed or induced), although the precise mechanisms and neural substrates of this facilitation remain unclear. We assessed mood and personality variables in 79 participants before they attempted to solve problems that can be solved by either an insight or an analytic strategy. Participants higher in positive mood solved more problems, and specifically more with insight, compared with participants lower in positive mood. fMRI was performed on 27 of the participants while they solved problems. Positive mood (and to a lesser extent and in the opposite direction, anxiety) was associated with changes in brain activity during a preparatory interval preceding each solved problem; modulation of preparatory activity in several areas biased people to solve either with insight or analytically. Analyses examined whether (a) positive mood modulated activity in brain areas showing responsivity during preparation; (b) positive mood modulated activity in areas showing stronger activity for insight than noninsight trials either during preparation or solution; and (c) insight effects occurred in areas that showed mood-related effects during preparation. Across three analyses, the ACC showed sensitivity to both mood and insight, demonstrating that positive mood alters preparatory activity in ACC, biasing participants to engage in processing conducive to insight solving. This result suggests that positive mood enhances insight, at least in part, by modulating attention and cognitive control mechanisms via ACC, perhaps enhancing sensitivity to detect non-prepotent solution candidates.     

Perinatal and early childhood risk factors associated with rheumatoid factor positivity in a healthy paediatric population

OBJECTIVE: To examine perinatal and childhood risk factors for the presence of rheumatoid factor in healthy children. METHODS: The Diabetes Autoimmunity Study in the Young (DAISY) is a longitudinal study of children at increased risk of type 1 diabetes, based on possession of human leucocyte antigen (HLA)-DR4 and DR3 alleles or a family history of diabetes. 651 children who participated in DAISY, with an average age of 6.4 (range 1-15) years, were tested for the presence of rheumatoid factor in their most recent serum sample. 23 children were positive for rheumatoid factor. Exposure data were collected prospectively by interview. HLA-DR4 alleles were identified using polymerase chain reaction-based Class II genotyping. RESULTS: While exploring risk factors for rheumatoid factor positivity in a multivariate model, several important interaction terms involving HLA-DR4 status suggested the need to evaluate risk factors in HLA-DR4-positive and HLA-DR4-negative children separately. In HLA-DR4-negative children, rheumatoid factor-positive infants were less likely to have been breast fed for >3 months (odds ratio (OR) 0.18; 95% confidence interval (CI) 0.04 to 0.99), more likely to have been exposed to non-parental tobacco smoke (OR 5.38; 95% CI 0.93 to 31.27) and more likely to be a race/ethnicity other than non-Hispanic white (OR 6.94; 95% CI 1.10 to 43.88) compared with rheumatoid factor-negative children, after adjusting for age, sex and maternal education. In HLA-DR4-positive children, there were no significantly associated risk factors for rheumatoid factor positivity. CONCLUSIONS: Risk factors for rheumatoid factor positivity in children vary by HLA-DR4 genotype. In HLA-DR4-negative children, breast feeding may decrease the risk, and environmental tobacco smoke may increase the risk, of autoimmunity.     

Slow-onset, long-duration, alkyl analogues of methylphenidate with enhanced selectivity for the dopamine transporter

Methylphenidate analogues, in which the carbomethoxy has been replaced by an alkyl group and with different phenyl substituents, have been synthesized and tested in monoamine transporter assays. As predicted from a pharmacophore model, most of the RR/SS diastereomers showed high potency as dopamine reuptake inhibitors. Analogues with a 4-chlorophenyl group and an unbranched initial alkyl atom had consistently enhanced selectivity for the dopamine transporter. The most potent compounds were those with a three- or four-carbon chain. The "inactive" RS/SR diastereomers showed substantial activity when the phenyl substituent was 3,4-dichloro. On a locomotor assay, one compound was found to have a slow onset and a long duration of action. The activity of these compounds provides additional evidence for a conformational/superposition model of methylphenidate with cocaine-like structures. A ketone analogue, obtained by hydrogenating a previously described vinylogous amide, had activity similar to that of methylphenidate.