Increased risk of severe acute pancreatitis in patients with diabetes

Aims We prospectively assessed the age- and sex-specific incidence rates and relative risks of overall and severe acute pancreatitis in Taiwanese with diabetes. Methods The study cohort included age- and-sex-matched groups of patients with (n?=?547?554) and without (n?=?584?373) diabetes. Incidence rate was estimated under Poisson assumption and relative risks of acute pancreatitis and severe acute pancreatitis, based on modified Atlanta criteria, were indicated by hazard ratios estimated from Cox proportional hazard regression models. Results Over an 8-year follow-up period, the incidence of acute pancreatitis was 2.98 and 1.68 per 1000 person-years for patients with and without diabetes, respectively, representing a covariate adjusted hazard ratio of 1.53 (95% confidence interval 1.49-1.58). Diabetes was associated with a significantly elevated risk of acute pancreatitis in all sex and age stratifications, with the highest hazard ratio noted for study subjects aged 相似文献   

Engineering a large protein by combined rational and random approaches: stabilizing the Clostridium thermocellum cellobiose phosphorylase

The Clostridium thermocellum cellobiose phosphorylase (CtCBP) is a large protein consisting of 812 amino acids and has great potential in the production of sugar phosphates, novel glycosides, and biofuels. It is relatively stable at 50 °C, but is rapidly inactivated at 70 °C. To stabilize CtCBP at elevated temperatures, two protein-engineering approaches were applied, i.e. site-directed mutagenesis based on structure-guided homology analysis and random mutagenesis at various mutation rates. The former chose substitutions by comparison of the protein sequences of CBP homologs, utilized structural information to identify key amino acid residues responsible for enhanced stability, and then created a few variants accurately. The latter constructed large libraries of random mutants at different mutagenesis frequencies. A novel combinational selection/screening strategy was employed to quickly isolate thermostability-enhanced and active variants. Several stability-enhanced mutants were obtained by both methods. Manually combining the stabilizing mutations identified from both rational and random approaches led to the best mutant (CM3) with the halftime of inactivation at 70 °C extended from 8.3 to 24.6 min. The temperature optimum of CM3 was increased from 60 to 80 °C. These results suggested that a combination of rational design and random mutagenesis could have a solid basis for engineering large proteins.     

Tracing genetic differentiation of Chinese Mongolian sheep using microsatellites

The genetic consequences of population differentiation and isolation have been the subject of conservation biology. In this study, we analysed the genetic diversity and structure of Mongolian sheep in China. These animals belong to a traditional local breed with high production, extensive adaption, early maturity and roughage resistance. For this purpose, 26 microsatellites were genotyped for five Mongolian sheep populations. The Bayesian clustering indicated five clusters as the most probable genetic structure of the populations investigated. In addition, a clear genetic structure was revealed in three populations distributed at large geographical scales, while the other cluster encompassed UQ and HLBR sheep that displayed no clear differentiation, probably due to their close and small geographical distributions. Overall, our results are helpful in understanding the interplay of population dynamics in these close genetic lineages of Mongolian sheep.     

USP4 targets TAK1 to downregulate TNFα-induced NF-κB activation

Lys63-linked polyubiquitination of transforming growth factor-β-activated kinase 1 (TAK1) has an important role in tumor necrosis factor-α (TNFα)-induced NF-κB activation. Using a functional genomic approach, we have identified ubiquitin-specific peptidase 4 (USP4) as a deubiquitinase for TAK1. USP4 deubiquitinates TAK1 in vitro and in vivo. TNFα induces association of USP4 with TAK1 to deubiquitinate TAK1 and downregulate TAK1-mediated NF-κB activation. Overexpression of USP4 wild type, but not deuibiquitinase-deficient C311A mutant, inhibits both TNFα- and TAK1/TAB1 co-overexpression-induced TAK1 polyubiquitination and NF-κB activation. Notably, knockdown of USP4 in HeLa cells enhances TNFα-induced TAK1 polyubiquitination, IκB kinase phosphorylation, IκBα phosphorylation and ubiquitination, as well as NF-κB-dependent gene expression. Moreover, USP4 negatively regulates IL-1β-, LPS- and TGFβ-induced NF-κB activation. Together, our results demonstrate that USP4 serves as a critical control to downregulate TNFα-induced NF-κB activation through deubiquitinating TAK1.     

Efficacy of specific IgY for treatment of lipopolysaccharide-induced endotoxemia using a mouse model

Aims: To estimate the efficacy of specific egg yolk immunoglobulin (IgY) for the treatment of lipopolysaccharide (LPS)‐induced endotoxemia using a mouse model. Methods and Results: Specific IgY was obtained from the yolk of hens immunized with formaldehyde‐killed Escherichia coli O111 and showed a high binding activity to LPS when subjected to an ELISA. Endotoxemia was induced in mice by intraperitoneal injection of LPS at a dose of 20 mg kg^?1 for measuring survival rate and 10 mg kg^?1 for cytokine measurement. The survival rate of mice treated with 200 mg kg^?1 specific IgY or 5 mg kg^?1 dexamethasone was 70% while none of the mice in the normal saline–treated group survived more than 7 days. Specific IgY significantly (P < 0·05) decreased tumour necrosis factor‐α (TNF‐α) level and increased interleukin‐10 (IL‐10) level in the serum of endotoxemia mice. Specific IgY had less of an effect on TNF‐α than dexamthasone, while its effect on increasing IL‐10 was stronger than dexamethasone. Haematoxylin and eosin–stained sections indicated that IgY attenuated the damage to the lung and liver observed in mice with endotoxemia. Conclusions: The specific IgY increased the survival rate of mice with endotoxemia induced by LPS, down‐regulated TNF‐α and up‐regulated IL‐10 in serum and attenuated the extent of damage to the lung and liver. Significance and Impact of the Study: The specific IgY has potential for the treatment of LPS‐induced endotoxemia.     

A combination of cilostazol and Ginkgo biloba extract protects against cisplatin-induced Cochleo-vestibular dysfunction by inhibiting the mitochondrial apoptotic and ERK pathways

Cisplatin (cis-diammine-dichloroplatinum; CDDP) is an anticancer drug that induces significant hearing loss and balance dysfunction as side effects. Cilostazol (CS, 6-[4-(1-cyclohexyl-1H-tetrazol-5-yl) butoxy]-3, 4-dihydro-2-(1H)-quinolinone) has neuroprotective and antioxidant effects, whereas Ginkgo biloba extract (GbE) has preventive effects on CDDP-induced hearing loss in rats, and GbE enhances the antiatherogenic effect of CS by inhibiting the generation of reactive oxygen species (ROS). The purpose of this study was to investigate the effects of renexin (RXN), which contains GbE and CS, against CDDP-induced cochleo-vestibular dysfunction in rats and to elucidate the mechanism underlying the protective effects of RXN on auditory cells. Rats intraperitoneally injected with CDDP exhibited an increase in hearing threshold and vestibular dysfunction, which agreed with hair cell damage in the Organ of Corti and otoliths. However, these impairments were significantly prevented in a dose-dependent manner by pre- and co-treatment with RXN, and these preventive effects in RXN-treated rats were more prominent than those in GbE-treated rats. In a CDDP pharmacokinetic study, platinum concentration was very similar between CDDP-only treated and RXN+CDDP cotreated rats. RXN markedly attenuated CDDP-induced intracellular ROS and significantly reduced CDDP-activated expression of p-extracellular regulated kinase (ERK), BAX, cytochrome c, cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase, but increased BCL-XL expression. These results show that RXN may have a synergistic effect by strongly protecting hearing and vestibular dysfunction induced by CDDP by inhibiting ROS production, mitochondrial pathways and the ERK pathway, without interfering with CDDP pharmacokinetics. Therefore, RXN could potentially be used to reduce CDDP-related hearing loss and dizziness.     

HMG-CoA reductase inhibitors induce apoptosis of lymphoma cells by promoting ROS generation and regulating Akt,Erk and p38 signals via suppression of mevalonate pathway

Statins, the inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are widely used cholesterol-lowering drugs. Convincing evidence indicates that statins stimulate apoptotic cell death in several types of proliferating tumor cells in a cholesterol-lowering-independent manner. The objective here was to elucidate the molecular mechanism by which statins induce lymphoma cells death. Statins (atorvastatin, fluvastatin and simvastatin) treatment enhanced the DNA fragmentation and the activation of proapoptotic members such as caspase-3, PARP and Bax, but suppressed the activation of anti-apoptotic molecule Bcl-2 in lymphoma cells including A20 and EL4 cells, which was accompanied by inhibition of cell survival. Both increase in levels of reactive oxygen species (ROS) and activation of p38 MAPK and decrease in mitochondrial membrane potential and activation of Akt and Erk pathways were observed in statin-treated lymphoma cells. Statin-induced cytotoxic effects, DNA fragmentation and changes of activation of caspase-3, Akt, Erk and p38 were blocked by antioxidant (N-acetylcysteine) and metabolic products of the HMG-CoA reductase reaction, such as mevalonate, farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP). These results suggests that HMG-CoA reductase inhibitors induce lymphoma cells apoptosis by increasing intracellular ROS generation and p38 activation and suppressing activation of Akt and Erk pathways, through inhibition of metabolic products of the HMG-CoA reductase reaction including mevalonate, FPP and GGPP.     

Cellulose solvent-based biomass pretreatment breaks highly ordered hydrogen bonds in cellulose fibers of switchgrass

The switchgrass (SG) samples pretreated by cellulose solvent‐ and organic solvent‐based lignocellulose fractionation were characterized by enzymatic hydrolysis, substrate accessibility assay, scanning electron microscopy, X‐ray diffraction (XRD), cross polarization/magic angle spinning (CP/MAS) ¹³C nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopy (FTIR). Glucan digestibility of the pretreated SG was 89% at hour 36 at one filter paper unit of cellulase per gram of glucan. Crystallinity index (CrI) of pure cellulosic materials and SG before and after cellulose solvent‐based pretreatment were determined by XRD and NMR. CrI values varied greatly depending on measurement techniques, calculation approaches, and sample drying conditions, suggesting that the effects of CrI data obtained from dried samples on enzymatic hydrolysis of hydrated cellulosic materials should be interpreted with caution. Fast hydrolysis rates and high glucan digestibilities for pretreated SG were mainly attributed to a 16.3‐fold increase in cellulose accessibility to cellulase from 0.49 to 8.0 m²/g biomass, because the highly ordered hydrogen‐bonding networks in cellulose fibers of biomass were broken through cellulose dissolution in a cellulose solvent, as evidenced by CP/MAS ¹³C‐NMR and FTIR. Biotechnol. Bioeng. 2011; 108:521–529. © 2010 Wiley Periodicals, Inc.     

Phospholipase D1 regulates autophagic flux and clearance of α-synuclein aggregates

Many neurodegenerative diseases, such as Alzheimer''s disease and Parkinson''s disease, are characterized by abnormal accumulations of aggregated proteins. Brains in these diseases also show accumulation of autophagic vesicles in the neuronal cytoplasm, suggesting impairment of the autophagic process. As autophagy involves de novo membrane production and vesicle fusion, extensive changes in lipid molecules are necessary. However, the involvement of signaling lipid-modifying enzymes in autophagy and their roles in neurodegenerative diseases are not clear. Using specific inhibitor, we show that loss of phospholipase D1 (PLD1) activity resulted in an accumulation of microtubule-associated protein light chain 3 (LC3), p62, and polyubiquitinated proteins, signs representing malfunction in autophagic flux. Fluorescence and electron microscopic analyses demonstrated impaired fusion of autophagosomes with lysosomes, resulting in accumulation of autophagosomes. Within the cells with impaired autophagic flux, α-synuclein aggregates accumulated in autophagosomes. Knockdown of PLD1 expression using small interfering RNA also resulted in impaired autophagic flux and accumulation of α-synuclein aggregates in autophagosomes. Neuronal toxicity caused by α-synuclein accumulation was rescued by overexpression of PLD1; however, expression of activity-deficient mutant, PLD1-KRM, showed reduced rescue effects. Finally, we demonstrated that both PLD activity and expression levels were reduced in brain tissues of dementia with Lewy bodies (DLB) patients, whereas the amounts of α-synuclein and p62 were increased in the same tissue samples. Collectively, these results suggest that insufficient PLD activity, and therefore, the changes in phospholipid compositions within membranes, might be an important contributor to impaired autophagic process and protein accumulation in Lewy body diseases.Macroautophagy is the best-characterized autophagy pathway that mediates the lysosomal degradation of the cytoplasmic organelles and proteins.¹ In this paper, macroautophagy will be simply referred to as autophagy. Autophagy may be characterized by nonspecific sequestration and degradation of the bulk cytoplasm, a process that recycles essential building blocks for production of macromolecules under conditions where nutrients are limited. Autophagy may also occur to selectively degrade polyubiquitinated targets, and this is often referred to as the quality control autophagy.² Many long-lived proteins and perhaps protein aggregates may be the substrates of the quality control autophagy.As being an essential process for macromolecular metabolism, perturbation of autophagy has been linked to various human diseases, such as neurodegenerative diseases, cancer, and infectious diseases.³ Autophagic dysfunction in neurons, in particular, causes accumulation of aggregation-prone proteins and neurodegeneration that are associated with various neurodegenerative diseases, including Alzheimer''s disease (AD), Parkinson''s disease (PD), and Huntington''s disease (HD).⁴ Recently, genetic mutations that are linked to some of the major neurodegenerative diseases have turned out to reside in the genes that are involved in multiple steps in the autophagic pathways,⁴ implicating the therapeutic potential of controlling autophagy.Autophagy involves sequestration of cytoplasmic substrates by a double-membraned compartment known as the autophagosome (AP).¹ Autophagy process initiates with the formation of a distinct structure referred to as the phagophore that extends its ends and seals in circle to form the AP. APs can fuse with various endosomal vesicles, forming amphisomes, and eventually fuse with lysosomes to form autolysosomes, where degradation of contents takes place. Autophagy involves a wide range of changes in membrane structures, such as de novo membrane biogenesis and membrane fusion. Therefore, lipid molecules and lipid-metabolizing enzymes must play essential roles in the autophagic process. A well-characterized such lipid enzyme is the class III phosphatidylinositol-3 kinase (PI3K), Vps34, that is essential for biogenesis of APs through interactions with various proteins.⁵ Other than Vps34, little has been known about the roles of lipid enzymes in autophagic process.In the current study, we explored the role of phospholipase D1 (PLD1) in autophagy and clearance of α-synuclein aggregates, suspected culprit of PD.⁶ PLD1 generates phosphatidic acid (PA) from phosphatidylcholine and has been known to be involved in intracellular vesicle trafficking.⁷ Our results suggest that PLD1 is an important player for maintaining autophagic flux via regulating autolysosome formation. We also showed that enzymatic inhibition and reduction in expression of PLD1 resulted in impaired clearance of α-synuclein aggregates. Finally, our data showed that reduced expression, and thus activity, of PLD1 was associated with Lewy body diseases.     

Desulfovibrio desulfuricans G20 tetraheme cytochrome structure at 1.5 Angstrom and cytochrome interaction with metal complexes

The structure of the type I tetraheme cytochrome c(3) from Desulfovibrio desulfuricans G20 was determined to 1.5 Angstrom by X-ray crystallography. In addition to the oxidized form, the structure of the molybdate-bound form of the protein was determined from oxidized crystals soaked in sodium molybdate. Only small structural shifts were obtained with metal binding, consistent with the remarkable structural stability of this protein. In vitro experiments with pure cytochrome showed that molybdate could oxidize the reduced cytochrome, although not as rapidly as U(VI) present as uranyl acetate. Alterations in the overall conformation and thermostability of the metal-oxidized protein were investigated by circular dichroism studies. Again, only small changes in protein structure were documented. The location of the molybdate ion near heme IV in the crystal structure suggested heme IV as the site of electron exit from the reduced cytochrome and implicated Lys14 and Lys56 in binding. Analysis of structurally conserved water molecules in type I cytochrome c(3) crystal structures identified interactions predicted to be important for protein stability and possibly for intramolecular electron transfer among heme molecules.