A mutant hemolysin with lower biological activity produced by a mutant Vibrio parahaemolyticus

Abstract A mutant toxin (m-TDH) of thermostable direct hemolysin (Vp-TDH) of Vibrio parahaemolyticus w was isolated from the culture of a strain of this organism mutagenized with N -methyl- N '-nitro- N -nitrosoguanidine. Although the m-TDH had a molecular structure similar to the native Vp-TDH, the m-TDH retained only about 7% residual hemolytic activity of the native toxin. Furthermore, other biological activities of m-TDH, such as lethality in mice and enterotoxicity in rabbit ileal loops, were also weakened. The m-TDH was immunologically indistinguishable from the native Vp-TDH. These results suggest that the m-TDH is only slightly different in structure from the native Vp-TDH. Also, the mutagenized site in m-TDH, which is not immunogenic, seems to be involved in expressing not only hemolytic activity but also lethal and enterotoxic activity.     

Assessment of genetic stability of the germplasm lines of medicinal plant <Emphasis Type="Italic">Scutellaria baicalensis</Emphasis> Georgi (Huang-qin) in long-term,in vitro maintained cultures

An approach of combining flow cytometry (FCM) analysis with morphological and chemical profiling was used to assess the genetic stability and bioactive compound diversity in a Scutellaria baicalensis Georgi (Huang-qin) germplasm collection that was clonally maintained in in vitro for a period of over 6 years. Based on the FCM analysis of nuclei samples from young shoots, the nuclear DNA content of S. baicalensis was calculated as 0.84 pg/2C. FCM analysis showed no significant variation in the nuclear DNA contents and ploidy levels in the long-term in vitro maintained germplasm lines. Germplasm lines, acclimatized to ex vitro conditions, exhibited distinctive plant growth and bioactive compound production capacities. The high level of genetic stability observed in in vitro maintained S. baicalensis lines opens up a variety of opportunities such as allowing long-term aseptic preservation and easy distribution of well-characterized germplasm lines of this medicinal plant species. This study represents a novel approach for continuous maintenance, monitoring, and production of medicinal plant tissues with specific chemistry.     

Covalent functionalization of multiwalled carbon nanotubes with a low molecular weight chitosan

Covalent functionalization of shortened multiwalled carbon nanotubes (MWNTs) with a natural low molecular weight chitosan (LMCS) was accomplished by a nucleophilic substitution reaction. Amino and primary hydroxyl groups of the LMCS contributed mainly to the formation of MWNT-LMCS conjugates. The LMCS content in the MWNT-LMCS is approximately 58 wt %, and approximately four molecular chains of the LMCS are attached to 1000 carbon atoms of the nanotube sidewalls. Most interestingly, the amorphous packing structure of the LMCS changed dramatically when it attached to the MWNTs. The MWNTs might induce the crystalline character of the LMCS. As a novel derivative of MWNTs, the MWNT-LMCS is soluble in dimethylformamide, dimethyl acetamide, dimethylsulfoxide, and acetic acid aqueous solution. The confirmation of the chitosan-based covalent functionalization route might lead to further studies aiming for potential applications in catalysis and environmental protection.     

GH-releasing peptides improve cardiac dysfunction and cachexia and suppress stress-related hormones and cardiomyocyte apoptosis in rats with heart failure

Growth hormone (GH)-releasing peptides (GHRP), a class of synthetic peptidyl GH secretagogues, have been reported to exert a cardioprotective effect on cardiac ischemia. However, whether GHRP have a beneficial effect on chronic heart failure (CHF) is unclear, and the present work aims to clarify this issue. At 9 wk after pressure-overload CHF was created by abdominal aortic banding in rats, one of four variants of GHRP (GHRP-1, -2, and -6 and hexarelin, 100 mug/kg) or saline was injected subcutaneously twice a day for 3 wk. Echocardiography and cardiac catheterization were performed to monitor cardiac function and obtain blood samples for hormone assay. GHRP treatment significantly improved left ventricular (LV) function and remodeling in CHF rats, as indicated by increased LV ejection fraction, LV end-systolic pressure, and diastolic posterior wall thickness and decreased LV end-diastolic pressure and LV end-diastolic dimension. GHRP also significantly alleviated development of cardiac cachexia, as shown by increases in body weight and tibial length in CHF rats. Plasma CA, renin, ANG II, aldosterone, endothelin-1, and atrial natriuretic peptide were significantly elevated in CHF rats but were significantly decreased in GHRP-treated CHF rats. GHRP suppressed cardiomyocyte apoptosis and increased cardiac GH secretagogue receptor mRNA expression in CHF rats. GHRP also decreased myocardial creatine kinase release in hypophysectomized rats subjected to acute myocardial ischemia. We conclude that chronic administration of GHRP alleviates LV dysfunction, pathological remodeling, and cardiac cachexia in CHF rats, at least in part by suppressing stress-induced neurohormonal activations and cardiomyocyte apoptosis.     

Application of hemicelluloses precipitated via ethanol treatment of pre-hydrolysis liquor in high-yield pulp

Hemicelluloses in industrially produced pre-hydrolysis liquor (PHL) were precipitated with ethanol. These PHL-derived hemicelluloses (PHL-EH) and a commercial, pure birch wood xylan sample (powder form) (BWX) were bleached using chlorine dioxide (D(0) and D(1)) and hydrogen peroxide (Ep) in the D(0)EpD(1) sequence, and the chemical compositions, molecular weights and charge densities of the treated samples were assessed. When applied to high-yield pulp (HYP) at 50 mg/g, 26 and 20 mg/g of the bleached PHL-EH and BWX, respectively, were adsorbed without significantly affecting paper properties. These results suggest that semi-bleached hemicelluloses could be used to increase the basis weight of paper products. Furthermore, an integrated process was proposed that converts the kraft-based dissolving pulp production process into a biorefinery unit with dissolving pulp, bleached hemicelluloses and lignin as main products.     

The Adverse Effects of Se Toxicity on Inflammatory and Immune Responses in Chicken Spleens

Selenium (Se) is an essential trace element, but excessive intake of Se could induce Se poisoning, and result in various health problems. NF-κB regulated many molecules of the immune response and the inflammatory response, and Th1/Th2 balance played a key in the regulation of immune response. The aim of this study is to investigate the role of NF-κB pathway and Th1/Th2 imbalance in the adverse influence of Se poisoning on chicken spleens. In the current study, 90 chickens were randomly divided into two groups (n?=?45 per group). The chickens were maintained either on a basal diet (the control group) containing 0.2 mg/kg Se or a high supplemented diet (the Se group) containing 15 mg/kg Se for 45 days. Then, we observed the pathohistology of spleen cells and detected NO content, iNOS activity, and the expression of NF-κB, iNOS, COX-2, PTGE, IL-6, TNF-α, Foxp3, IL-4, and IFN-γ in chicken spleens. In chicken spleens of the Se group, the result showed typical characteristics of inflammation: the content of NO and the activity of iNOS were increased, and the expression of NF-κB, iNOS, COX-2, PTGE, IL-6, TNF-α, and IL-4 was enhanced and that of Foxp3 and IFN-γ was decreased. Our study showed that Se toxicity could promote inflammation via NF-κB pathway, impairing the immune function, and changing Th1/Th2 balance in the chicken spleens.     

Preferential Release of Newly Synthesized Insulin Assessed by a Multi-Label Reporter System Using Pancreatic β-Cell Line MIN6

Newly synthesized hormones have been suggested to be preferentially secreted by various neuroendocrine cells. This observation indicates that there is a distinct population of secretory granules containing new and old hormones. Recent development of fluorescent timer proteins used in bovine adrenal chromaffin cells revealed that secretory vesicles segregate into distinct age-dependent populations. Here, we verify the preferential release of newly synthesized insulin in the pancreatic β-cell line, MIN6, using a combination of multi-labeling reporter systems with both fluorescent and biochemical procedures. This system allows hormones or granules of any age to be labeled, in contrast to the timer proteins, which require fluorescence shift time. Pulse-chase labeling with different color probes distinguishes insulin secretory granules by age, with younger granules having a predominantly intracellular localization rather than at the cell periphery.     

Effect of solar particle event radiation on gastrointestinal tract bacterial translocation and immune activation

Space flight conditions within the protection of Earth's gravitational field have been shown to alter immune responses, which could lead to potentially detrimental pathology. An additional risk of extended space travel outside the Earth's gravitational field is the effect of solar particle event (SPE) radiation exposure on the immune system. Organisms that could lead to infection include endogenous, latent viruses, colonizing pathogenics, and commensals, as well as exogenous microbes present in the spacecraft or other astronauts. In this report, the effect of SPE-like radiation on containment of commensal bacteria and the innate immune response induced by its breakdown was investigated at the radiation energies, doses and dose rates expected during an extravehicular excursion outside the Earth's gravitational field. A transient increase in serum lipopolysaccharide was observed 1 day after irradiation and was accompanied by an increase in acute-phase reactants and circulating proinflammatory cytokines, indicating immune activation. Baseline levels were reestablished by 5 days postirradiation. These findings suggest that astronauts exposed to SPE radiation could have impaired containment of colonizing bacteria and associated immune activation.     

Convenient enzymatic synthesis of a p-nitrophenyl oligosaccharide series of sialyl N-acetyllactosamine, sialyl Le x and relevant compounds

From the beta-D-Gal-(1-->4)-beta-D-GlcNAc-OC6H4NO2-p (1) prepared by the transglycosylation of beta-galactosidase from Bacillus circulans, alpha-D-Neu5Ac-(2-->3)-beta-D-Gal-(1-->4)-beta-D-GlcNAc-OC6H4NO2-p (9) and alpha-D-Neu5Ac-(2-->6)-beta-D-Gal-(1-->4)-beta-D-GlcNAc-OC6H4NO2-p (10) were effectively synthesized with an equimolar ratio of CMP-Neu5Ac by recombinant rat alpha-(2-->3)-N-sialyltransferase and rat liver alpha-(2-->6)-N-sialyltransferase, respectively. The former enzyme also transferred effectively the Neu5Ac residue from CMP-Neu5Ac to the location of OH-3 in the non-reducing terminal of beta-D-Gal-(1-->4)-beta-D-Gal-OC6H4NO2-p or beta-D-Gal-(1-->4)-beta-D-Gal-(1-->4)-beta-D-GlcNAc-OC6H4NO2-p, while the latter enzyme did not. In the case of equimolar ratio of GDP-Fuc/acceptor, 1 and 9 were further fucosylated quantitatively to form beta-D-Gal-(1-->4)-beta-D-(alpha-l-Fuc-(1-->3)-)-GlcNAc-OC6H4NO2-p (14) and alpha-D-Neu5Ac-(2-->3)-beta-D-Gal-(1-->4)-beta-D-(alpha-l-Fuc-(1-->3)-)-GlcNAc-OC6H4NO2-p (13) by recombinant human alpha-(1-->3)-fucosyltransferase VII, respectively.