Computational study of bindings of HL9, a nonapeptide fragment of human lysozyme, to HIV-1 fusion protein gp41

HL9 is a nonapeptide fragment of human lysozyme which has been shown to have anti-HIV-1 activity in nanomolar concentration. This study aims to explain this inhibitory activity by using molecular dynamics (MD) simulation, focusing on the ectodomain of gp41, the envelope glycoprotein of HIV-1 crucial to membrane fusion. It was found that in HL9, two Trp residues separated by two others occupy the conserved hydrophobic pocket on gp41 and thus inhibit fusion in dominant-negative manner. Detailed HL9-gp41 binding interactions and free energies of binding were obtained through MD simulation and solvated interaction energies (SIE) calculation, giving a binding free energy of −8.25 kcal/mol which is in close agreement with the experimental value of −9.96 kcal/mol. Since C-helical region (C34) of gp41 also has two Trp residues separated by two others, this arrangement may be generalised and used to scan peptide library and to find those having similar manner of inhibition.     

The role of sialyl glycan recognition in host tissue tropism of the avian parasite Eimeria tenella

Eimeria spp. are a highly successful group of intracellular protozoan parasites that develop within intestinal epithelial cells of poultry, causing coccidiosis. As a result of resistance against anticoccidial drugs and the expense of manufacturing live vaccines, it is necessary to understand the relationship between Eimeria and its host more deeply, with a view to developing recombinant vaccines. Eimeria possesses a family of microneme lectins (MICs) that contain microneme adhesive repeat regions (MARR). We show that the major MARR protein from Eimeria tenella, EtMIC3, is deployed at the parasite-host interface during the early stages of invasion. EtMIC3 consists of seven tandem MAR1-type domains, which possess a high specificity for sialylated glycans as shown by cell-based assays and carbohydrate microarray analyses. The restricted tissue staining pattern observed for EtMIC3 in the chicken caecal epithelium indicates that EtMIC3 contributes to guiding the parasite to the site of invasion in the chicken gut. The microarray analyses also reveal a lack of recognition of glycan sequences terminating in the N-glycolyl form of sialic acid by EtMIC3. Thus the parasite is well adapted to the avian host which lacks N-glycolyl neuraminic acid. We provide new structural insight into the MAR1 family of domains and reveal the atomic resolution basis for the sialic acid-based carbohydrate recognition. Finally, a preliminary chicken immunization trial provides evidence that recombinant EtMIC3 protein and EtMIC3 DNA are effective vaccine candidates.     

Cell cycle regulation and cytoskeletal remodelling are critical processes in the nutritional programming of embryonic development

Many mechanisms purport to explain how nutritional signals during early development are manifested as disease in the adult offspring. While these describe processes leading from nutritional insult to development of the actual pathology, the initial underlying cause of the programming effect remains elusive. To establish the primary drivers of programming, this study aimed to capture embryonic gene and protein changes in the whole embryo at the time of nutritional insult rather than downstream phenotypic effects. By using a cross-over design of two well established models of maternal protein and iron restriction we aimed to identify putative common "gatekeepers" which may drive nutritional programming.Both protein and iron deficiency in utero reduced the nephron complement in adult male Wistar and Rowett Hooded Lister rats (P<0.05). This occurred in the absence of damage to the glomerular ultrastructure. Microarray, proteomic and pathway analyses identified diet-specific and strain-specific gatekeeper genes, proteins and processes which shared a common association with the regulation of the cell cycle, especially the G1/S and G2/M checkpoints, and cytoskeletal remodelling. A cell cycle-specific PCR array confirmed the down-regulation of cyclins with protein restriction and the up-regulation of apoptotic genes with iron deficiency.The timing and experimental design of this study have been carefully controlled to isolate the common molecular mechanisms which may initiate the sequelae of events involved in nutritional programming of embryonic development. We propose that despite differences in the individual genes and proteins affected in each strain and with each diet, the general response to nutrient deficiency in utero is perturbation of the cell cycle, at the level of interaction with the cytoskeleton and the mitotic checkpoints, thereby diminishing control over the integrity of DNA which is allowed to replicate. These findings offer novel insight into the primary causes and mechanisms leading to the pathologies which have been identified by previous programming studies.     

Justified concern or exaggerated fear: the risk of anaphylaxis in percutaneous treatment of cystic echinococcosis-a systematic literature review

Percutaneous treatment (PT) emerged in the mid-1980s as an alternative to surgery for selected cases of abdominal cystic echinococcosis (CE). Despite its efficacy and widespread use, the puncture of echinococcal cysts is still far from being universally accepted. One of the main reasons for this reluctance is the perceived risk of anaphylaxis linked to PTs. To quantify the risk of anaphylactic reactions and lethal anaphylaxis with PT, we systematically searched MEDLINE for publications on PT of CE and reviewed the PT-related complications. After including 124 publications published between 1980 and 2010, we collected a total number of 5943 PT procedures on 5517 hepatic and non-hepatic echinococcal cysts. Overall, two cases of lethal anaphylaxis and 99 reversible anaphylactic reactions were reported. Lethal anaphylaxis occurred in 0.03% of PT procedures, corresponding to 0.04% of treated cysts, while reversible allergic reactions complicated 1.7% of PTs, corresponding to 1.8% of treated echinococcal cysts. Analysis of the literature shows that lethal anaphylaxis related to percutaneous treatment of CE is an extremely rare event and is observed no more frequently than drug-related anaphylactic side effects.     

Purification, immobilization, and characterization of a specific lipase from Staphylococcus warneri EX17 by enzyme fractionating via adsorption on different hydrophobic supports

Staphylococcus warneri strain EX17 produces three lipases with different molecular weights of 28, 30, and 45 kDa. The 45 kDa fraction (SWL-45) has been purified from crude protein extracts by one chromatographic step based on the selective adsorption of this lipase by interfacial activation on different hydrophobic supports at low ionic strength. The adsorption of SWL-45 on octyl-Sepharose increased the enzyme activity by 60%, but the other lipases were also adsorbed on this support. Using butyl-Toyopearl, which is a lesser hydrophobic support, the purification factor was close to 20, and the only protein band detected on the sodium dodecyl sulfate-polyacrylamide electrophoresis analysis gel was that corresponding to the SWL-45, which could be easily desorbed from the support by incubation with triton X-100, producing a purified enzyme. SWL-45 was immobilized under very mild conditions on cyanogen bromide Sepharose, showing similar activities and stability as for its soluble form but without intermolecular interaction. The effects of different detergents over the activity of the immobilized SWL-45 were analyzed, which was hyperactivated by factors of 1.3 and 2.5 with 0.01% Tween 80 and 0.1% Triton X-100, respectively, while ionic detergents produced detrimental effects on the enzyme activity even at very low concentrations. Optimal reaction conditions and the effect of other additives on the enzyme activity were also investigated.     

Polyhydroxy fullerenes (fullerols or fullerenols): beneficial effects on growth and lifespan in diverse biological models

Recent toxicological studies on carbon nanomaterials, including fullerenes, have led to concerns about their safety. Functionalized fullerenes, such as polyhydroxy fullerenes (PHF, fullerols, or fullerenols), have attracted particular attention due to their water solubility and toxicity. Here, we report surprisingly beneficial and/or specific effects of PHF on model organisms representing four kingdoms, including the green algae Pseudokirchneriella subcapitata, the plant Arabidopsis thaliana, the fungus Aspergillus niger, and the invertebrate Ceriodaphnia dubia. The results showed that PHF had no acute or chronic negative effects on the freshwater organisms. Conversely, PHF could surprisingly increase the algal culture density over controls at higher concentrations (i.e., 72% increase by 1 and 5 mg/L of PHF) and extend the lifespan and stimulate the reproduction of Daphnia (e.g. about 38% by 20 mg/L of PHF). We also show that at certain PHF concentrations fungal growth can be enhanced and Arabidopsis thaliana seedlings exhibit longer hypocotyls, while other complex physiological processes remain unaffected. These findings may open new research fields in the potential applications of PHF, e.g., in biofuel production and aquaculture. These results will form the basis of further research into the mechanisms of growth stimulation and life extension by PHF.     

Impact of continuous and pulsatile insulin delivery on net hepatic glucose uptake

The pancreas releases insulin in a pulsatile manner; however, studies assessing the liver's response to insulin have used constant infusion rates. Our aims were to determine whether the secretion pattern of insulin [continuous (CON) vs. pulsatile] in the presence of hyperglycemia 1) influences net hepatic glucose uptake (NHGU) and 2) entrains NHGU. Chronically catheterized conscious dogs fasted for 42 h received infusions including peripheral somatostatin, portal insulin (0.25 mU x kg(-1) x min(-1)), peripheral glucagon (0.9 ng x kg(-1) x min(-1)), and peripheral glucose at a rate double the glucose load to the liver. After the basal period, insulin was infused for 210 min at either four times the basal rate (1 mU x kg(-1) x min(-1)) or an identical amount in pulses of 1 and 4 min duration, followed by intervals of 11 and 8 min (CON, 1/11, and 4/8, respectively) in which insulin was not infused. A variable peripheral glucose infusion containing [3H]glucose clamped glucose levels at twice the basal level ( approximately 200 mg/dl) throughout each study. Hepatic metabolism was assessed by combining tracer and arteriovenous difference techniques. Arterial plasma insulin (microU/ml) either increased from basal levels of 6 +/- 1 to a constant level of 22 +/- 4 in CON or oscillated from 5 +/- 1 to 416 +/- 79 and from 6 +/- 1 to 123 +/- 43 in 1/11 and 4/8, respectively. NHGU (-0.8 +/- 0.3, 0.4 +/- 0.2, and -0.9 +/- 0.4 mg x kg(-1) x min(-1)) and net hepatic fractional extraction of glucose (0.04 +/- 0.01, 0.04 +/- 0.01, and 0.05 +/- 0.01 mg x kg(-1) x min(-1)) were similar during the experimental period. Spectral analysis was performed to assess whether a correlation existed between the insulin secretion pattern and NHGU. NHGU was not augmented by pulsatile insulin delivery, and there is no evidence of entrainment in hepatic glucose metabolism. Thus the loss of insulin pulsatility per se likely has little or no impact on the effectiveness of insulin in regulating liver glucose uptake.     

Green tea polyphenol extract attenuates colon injury induced by experimental colitis

Inflammatory bowel disease (IBD) is characterised by oxidative and nitrosative stress, leukocyte infiltration, and up-regulation of intercellular adhesion molecule 1 (ICAM-1) expression in the colon. The aim of the present study was to examine the effects of green tea extract in rats subjected to experimental colitis induced by intracolonic instillation of dinitrobenzene sulphonic acid (DNBS). At 4 days after DNBS administration the rats were sacrificed. Treatment with green tea extract significantly attenuated diarrhoea and loss of body weight. This was associated with a remarkable amelioration of the disruption of the colonic architecture, significant reduction of colonic myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-alpha) production. Green tea extract also reduced the appearance of nitrotyrosine immunoreactivity in the colon and reduced the up-regulation of ICAM-1.