Heavy metal hydrolysis of polyisoprenoid-phosphate mono- and oligosaccarides

Summary Mono- and oligosaccharide derivatives of dolichol phosphate can be hydrolyzed by heavy metal, preferably Zn⁺⁺ at 100°C or 65°C. The reactions follow first order kinetics. The reaction proceeds through hydrolysis of the sugar phosphate bond.This work was supported by GB No. 38335.     

Activitéin vivo de dérivés de la thiourée contre le virus de l'influenza

Summary A large number of sulphur-containing compounds bearing the thiourea group -NH-CS-NH-, including substituted thiocarbanilides, 1-acyl-4-arylthiosemicar-bazides, 1-(arylaminothioformyl)-thiosemicarbazides, 4-aryl-1-(arylaminothioformyl)- thiosemicarbazides, and other related substances have been tested for potential antiviral activity. Several of these compounds have been found chemotherapeutically active against influenza virus.

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Communication présentée au Congrès international de Chimie pure et appliquée de Zürich (Juillet 1955).     

Modeling and Forecasting the Yield Curve by an Extended Nelson‐Siegel Class of Models: A Quantile Autoregression Approach

This paper compares the in‐sample fitting and the out‐of‐sample forecasting performances of four distinct Nelson–Siegel class models: Nelson–Siegel, Bliss, Svensson, and a five‐factor model we propose in order to enhance the fitting flexibility. The introduction of the fifth factor resulted in superior adjustment to the data. For the forecasting exercise the paper contrasts the performances of the term structure models in association with the following econometric methods: quantile autoregression evaluated at the median, VAR, AR, and a random walk. As a pattern, the quantile procedure delivered the best results for longer forecasting horizons. Copyright © 2011 John Wiley & Sons, Ltd.     

Mutations in SEC63 cause autosomal dominant polycystic liver disease

Mutations in PRKCSH, encoding the beta-subunit of glucosidase II, an N-linked glycan-processing enzyme in the endoplasmic reticulum (ER), cause autosomal dominant polycystic liver disease. We found that mutations in SEC63, encoding a component of the protein translocation machinery in the ER, also cause this disease. These findings are suggestive of a role for cotranslational protein-processing pathways in maintaining epithelial luminal structure and implicate noncilial ER proteins in human polycystic disease.     

The impact of cyclin-dependent kinase 5 depletion on poly(ADP-ribose) polymerase activity and responses to radiation

Cyclin-dependent kinase 5 (Cdk5) has been identified as a determinant of sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors. Here, the consequences of its depletion on cell survival, PARP activity, the recruitment of base excision repair (BER) proteins to DNA damage sites, and overall DNA single-strand break (SSB) repair were investigated using isogenic HeLa stably depleted (KD) and Control cell lines. Synthetic lethality achieved by disrupting PARP activity in Cdk5-deficient cells was confirmed, and the Cdk5^KD cells were also found to be sensitive to the killing effects of ionizing radiation (IR) but not methyl methanesulfonate or neocarzinostatin. The recruitment profiles of GFP-PARP-1 and XRCC1-YFP to sites of micro-irradiated Cdk5^KD cells were slower and reached lower maximum values, while the profile of GFP-PCNA recruitment was faster and attained higher maximum values compared to Control cells. Higher basal, IR, and hydrogen peroxide-induced polymer levels were observed in Cdk5^KD compared to Control cells. Recruitment of GFP-PARP-1 in which serines 782, 785, and 786, potential Cdk5 phosphorylation targets, were mutated to alanines in micro-irradiated Control cells was also reduced. We hypothesize that Cdk5-dependent PARP-1 phosphorylation on one or more of these serines results in an attenuation of its ribosylating activity facilitating persistence at DNA damage sites. Despite these deficiencies, Cdk5^KD cells are able to effectively repair SSBs probably via the long patch BER pathway, suggesting that the enhanced radiation sensitivity of Cdk5^KD cells is due to a role of Cdk5 in other pathways or the altered polymer levels.     

Murine arylsulfatase C: Evidence for two isozymes

Summary SWR/J mice posses high arylsulfatase C, estrone sulfatase, and dehydroepiandrosterone sulfatase activities in liver, spleen and kidney compared to A/J mice. This internstrain activity variation appears to be determined by at least 1 autosomal gene. Murine arylsulfatase C activity occurs in both hydrophobic and hydrophilic forms which differ with respect to certain biochemical properties and exhibit different subcellular distributions. The hydrophilic isozyme is a major component in kidney and brain extracts and a minor isozyme in liver and spleen extracts. The hydrophobic arylsulfatase C isozyme appears to be identical to steroid sulfatase. The hydrophilic arylsulfatase C isozyme does not possess steroid sulfatase activity; however, hydrophilic and hydrophobic arylsulfatase C share certain properties, suggesting that they may be structurally related. The autosomal gene(s) affects both arylsulfatase isozymes.This research was supported in part by National Institutes of Health grant GM 27707.     

Superoxide dismutase activity during the plasmodial life cycle ofPhysarum polycephalum

Summary Superoxide dismutase activity was slow throughout the cell cycle of surface cultures ofPhysarum polycephalum. This activity increased markedly when the organism was induced to spherulate. Glutathione (GSH) and hydrogen peroxide (H₂O₂) concentrations changed very little during the cell cycle. During spherulation GSH decreased; H₂O₂ and the cyanide-resistant respiration of plasmodial homogenates increased.     

Affinity chromatography of glucose dehydrogenase

Porcine liver beta-D-glucose dehydrogenase, a multi-functional protein, has been purified to apparent homogeneity. The enzyme has been separated from the endoplasmic reticulum using Triton X-114 and further purified using NAD to release glucose dehydrogenase from a NADP-linked sepharose column. The purified enzyme is capable of producing both NADH and NADPH in vivo as indicated by kinetic studies.