Birnavirus VP1 proteins form a distinct subgroup of RNA-dependent RNA polymerases lacking a GDD motif

We have cloned and characterized the Drosophila X virus (DXV) genome segment B and its encoded VP1, the putative RNA-dependent RNA polymerase (RdRp) present in the virion. The 2991-bp open reading frame encodes the largest birnavirus VP1 at 977 aa, with a calculated M(r) of 112.8 kDa. As with the VP1 proteins of the type species of the other two genera in the family Birnaviridae, namely, infectious pancreatic necrosis virus (genus Aquabirnavirus) and infectious bursal disease virus (genus Avibirnavirus), the DXV (genus Entomobirnavirus) VP1 protein contains a consensus GTP-binding site and appears to possess self-guanylylation activity. All of the birnavirus VP1 proteins contain conserved RdRp motifs that reside in the catalytic "palm" domain of all classes of polymerases. However, the birnavirus RdRps lack the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain of other RdRps. All three birnavirus RdRps do contain downstream DD motifs that could function as part of the catalytic triad. These motifs are, however, located in spatially distinct regions of the various birnavirus VP1 proteins. These results suggest that the VP1 proteins of birnaviruses form a defined subgroup of polymerases that either are lacking the conserved RdRp motif VI or have repositioned this motif to different structural regions.     

The detection and differentiation of foot-and-mouth disease viruses using solid-phase nucleic acid hybridization

Thirteen complementary DNA (cDNA) probes were used to detect the presence of foot-and-mouth disease virus (FMDV) RNA extracted from cell cultures. When labelled with 32P, these probes enabled the detection of 1 pg of FMDV-RNA, or 1 virus copy per cell. Two FMDV A12 probes that coded for the leader, structural protein VP1 region and part of the polymerase gene respectively, showed no hybridization with other closely related picornaviruses. Differentiation between FMDV serotypes A, O and C was possible, using cDNA probes from individual serotypes that corresponded to structural protein VP1.     

Fatal meningoencephalitis due to Bacillus anthracis

Abstract: We report the first case of fatal anthrax meningoencephalitis in Hong Kong over the past 60 years. A 13 year-old boy presented with right lower quadrant pain, diarrhoea and progressive headache. Lumbar puncture yielded gram positive bacilli initially thought to be Bacillus cereus, a contaminant. He was treated with ampicillin and cefotaxime, but died 3 days after hospitalization. The organism isolated from blood and cerebrospinal fluid was later identified as Bacillus anthracis.     

A prospective study of methylenetetrahydrofolate reductase and methionine synthase gene polymorphisms, and risk of colorectal adenoma

We examined the relationship between a functional polymorphism (667C-- >T, ala-->val) of the methylenetetrahydrofolate reductase gene (MTHFR) and the risk of colorectal adenomas in the prospective Nurses' Health Study. Among 257 incident polyp cases and 713 controls, the MTHFR val/val polymorphism [relative risk (RR) = 1.35, 95% confidence interval (CI) 0.84-2.17] was not significantly associated with risk of adenomas. This lack of association was observed for both small (RR = 1.36, 95% CI 0.76-2.45) and large (RR = 1.32, 95% CI 0.66-2.66) adenomas. Furthermore, there was no significant interaction between this polymorphism and consumption of either folate, methionine or alcohol. We also examined the relationship of a newly identified polymorphism (asp919gly) of the methionine synthase gene (MS) with the risk of colorectal adenomas in the same population. The MS gly/gly polymorphism was also not significantly associated with risk of colorectal adenomas (RR = 0.66, 95% CI 0.26-1.70). These results, which need to be confirmed in other studies, suggest that the MTHFR val/val polymorphism, which has been previously inversely associated with risk of colorectal cancer, plays a role only in a late stage (adenoma-- >carcinoma) of colorectal tumorigenesis, and/or may protect against malignant transformation in the subset of benign adenomas, which may progress to malignancy.      

Does prenylation predict progression in NAFLD?

Non-alcoholic fatty liver disease (NAFLD) often develops in concert with related metabolic diseases, such as obesity, dyslipidemia and insulin resistance. Prolonged lipid accumulation and inflammation can progress to non-alcoholic steatohepatitis (NASH). Although factors associated with the development of NAFLD are known, triggers for the progression of NAFLD to NASH are poorly understood. Recent findings published in The Journal of Pathology reveal the possible regulation of NASH progression by metabolites of the mevalonate pathway. Mevalonate can be converted into the isoprenoids farnesyldiphosphate (FPP) and geranylgeranyl diphosphate (GGPP). GGPP synthase (GGPPS), the enzyme that converts FPP to GGPP, is dysregulated in humans and mice during NASH. Both FPP and GGPP can be conjugated to proteins through prenylation, modifying protein function and localization. Deletion or knockdown of GGPPS favors FPP prenylation (farnesylation) and augments the function of liver kinase B1, an upstream kinase of AMP-activated protein kinase (AMPK). Despite increased AMPK activation, livers in Ggpps-deficient mice on a high-fat diet poorly oxidize lipids due to mitochondrial dysfunction. Although work from Liu et al provides evidence as to the potential importance of the prenylation portion of the mevalonate pathway during NAFLD, future studies are necessary to fully grasp any therapeutic or diagnostic potential. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Determination of adequate coronary stent expansion using StentBoost, a novel fluoroscopic image processing technique.

OBJECTIVE: We tested the hypothesis that the use of motion-corrected fluoroscopic images results in enhanced coronary stent visualization and improved detection of inadequate stent expansion. BACKGROUND: Intravascular ultrasound (IVUS) more accurately detects inadequate stent expansion when compared with coronary angiography. Stent under-expansion is associated with stent restenosis and thrombosis. Developing a technique to improve fluoroscopic-based assessment of stent expansion is desirable. METHODS: We analyzed measurements of 48 coronary stents implanted in 30 patients using quantitative coronary angiography (QCA), IVUS, and StentBoost (SB), a novel fluoroscopic image processing technique. Correlations of stent diameter between the modalities were determined. Using established IVUS criteria for adequate stent deployment, we assessed the diagnostic test characteristics of SB to detect inadequate stent expansion. RESULTS: Correlations of minimum stent diameter were highest between IVUS and SB (r=0.75; P<0.0001) when compared with QCA and IVUS (r=0.65; P<0.0001), and QCA and SB (r=0.49; P=0.0004). IVUS and SB demonstrated a small difference in minimum stent diameter, 0.043 mm (95% CI: 0.146-0.061 mm). The correlation between IVUS and SB was lower for vessels with intimal calcification (r=0.57; P=0.002) when compared with vessels with deeper calcification (r=0.84; P<0.0001). A SB minimum diameter of <2.5 mm predicted inadequate stent expansion by IVUS with 88% sensitivity, 70% specificity, and a positive likelihood ratio of 2.9. CONCLUSIONS: SB had superior correlations for stent expansion measured by IVUS when compared with QCA. A minimum stent diameter by SB measurement<2.5 mm is associated with inadequate stent expansion using IVUS criteria.