In vitro anti-hyperglycemia properties of the aqueous stem bark extract from Strychnos henningsii (Gilg)

Strychnos henningsii (SH) is a plant commonly used in southern African traditional medicine for the management of diabetes mellitus. Previous in vivo studies showed that a stem bark extract improves glycemic control in a diabetic animal model. Meanwhile, the mechanism of action has not been elucidated. The present study therefore investigated various in vitro models known to target glucose homeostasis and its direct complications. The plant extract was found to stimulate both basal and insulin stimulated glucose uptake in differentiated 3T3-L1 cells but not in Chang liver cells. The effect on 3T3-L1 cells appears independent of PPARγ as the extract did not stimulate adipogenesis. Although, SH extract was inhibitory toward intestinal alpha glucosidase, the physiological relevance is doubtful based on the recommended dosages. The extract strongly inhibited protein glycation which, at least in part, may be explained by the antioxidant and phenolic content of this plant. Cytotoxicity in Chang liver cells yielded an IC₅₀ value of 130.0 μg/mL raising concern that continual exposure to this herbal remedy may initiate hepatotoxicity. The finding from this study suggests that SH extract may attenuate hyperglycemia through enhanced peripheral tissue glucose utilization.     

Intragastric pH during continuous infusion with pantoprazole in patients with bleeding peptic ulcer

OBJECTIVES: In managing patients with bleeding peptic ulcers, prevention of rebleeding is a particular challenge to hemostasis and fibrinolysis, both of which involve reactions that are impaired in acidic gastric environment. Therefore, such patients are expected to benefit from profound acid suppression. The present investigation aimed to establish a safe and, with regard to pH elevation, effective treatment that, based on in vitro evidence, should provide clinical benefit in this patient population. METHODS: Patients with acute bleeding peptic ulcers (Forrest Ia, Ib, IIa) after successful endoscopic hemostasis were enrolled in two pilot studies (N = 20 each). They were given an intravenous bolus injection of 80 mg of pantoprazole immediately followed by continuous infusion of either 6 mg/h or 8 mg/h pantoprazole for 72 h. Intragastric pH was measured continuously over 24 h and, if possible, for up to 48 h. RESULTS: Intragastric pH increased rapidly to values of about 6 with both treatments. For the 0-24 h period, the median pH values were 6.1 (68% range 4.5-7.4) and 6.1 (68% range 5.2-6.7) in patients receiving 6 mg/h and 8 mg/h continuous infusion, respectively; the values for the 0-48 h period were 5.9 (4.9-6.7) and 6.3 (5.5-7.0), respectively. The median percentage time that pH was > or =6 during the 0-48 h interval was 47% (68% range 28-89) for the 6 mg/h treatment group and 64% (68% range 41-84) for the 8 mg/h treatment group. Both treatment regimens with pantoprazole were well tolerated based on electrocardiographic measurements, vital signs, clinical laboratory values, and adverse events. CONCLUSIONS: Compared with the infusion with 6 mg/h pantoprazole, the continuous infusion of 8 mg/h pantoprazole showed a lower interindividual variability of the intragastric pH and a greater percentage of time that pH was >/ or =6. Thus, with regard to safety and efficacy, an initial 80-mg bolus injection, followed by 8 mg/h continuous infusion, seems to be the adequate treatment in patients with a high risk of rebleeding.     

Bacterial genome reduction using the progressive clustering of deletions via yeast sexual cycling

The availability of genetically tractable organisms with simple genomes is critical for the rapid, systems-level understanding of basic biological processes. Mycoplasma bacteria, with the smallest known genomes among free-living cellular organisms, are ideal models for this purpose, but the natural versions of these cells have genome complexities still too great to offer a comprehensive view of a fundamental life form. Here we describe an efficient method for reducing genomes from these organisms by identifying individually deletable regions using transposon mutagenesis and progressively clustering deleted genomic segments using meiotic recombination between the bacterial genomes harbored in yeast. Mycoplasmal genomes subjected to this process and transplanted into recipient cells yielded two mycoplasma strains. The first simultaneously lacked eight singly deletable regions of the genome, representing a total of 91 genes and ∼10% of the original genome. The second strain lacked seven of the eight regions, representing 84 genes. Growth assay data revealed an absence of genetic interactions among the 91 genes under tested conditions. Despite predicted effects of the deletions on sugar metabolism and the proteome, growth rates were unaffected by the gene deletions in the seven-deletion strain. These results support the feasibility of using single-gene disruption data to design and construct viable genomes lacking multiple genes, paving the way toward genome minimization. The progressive clustering method is expected to be effective for the reorganization of any mega-sized DNA molecules cloned in yeast, facilitating the construction of designer genomes in microbes as well as genomic fragments for genetic engineering of higher eukaryotes.Complexities of natural biological systems make it difficult to understand and define precisely the roles of individual genes and their integrated functions. The use of model organisms with a relatively small number of genes enables the isolation of core biological processes from their complex regulatory networks for extensive characterization. However, even the simplest natural microbes contain many genes of unknown function, as well as genes that can be singly or simultaneously deleted without any noticeable effect on growth rate in a laboratory setting (Hutchison et al. 1999; Glass et al. 2006; Posfai et al. 2006). Ill-defined genes and those mediating functional redundancies both compound the challenge of understanding even the simplest life forms.Toward generating a minimal cell where every gene is essential for the axenic viability of the organism, we are pursuing strategies to reduce the 1-Mb genome of Mycoplasma mycoides JCVI-syn1.0 (Gibson et al. 2010). Because we can (1) introduce this genome into yeast and maintain it as a plasmid (Benders et al. 2010; Karas et al. 2013a); and (2) “transplant” the genome from yeast into mycoplasma recipient cells (Lartigue et al. 2009), genetic tools in yeast are available for reducing this bacterial genome. Several systems offer advanced tools for bacterial genome engineering. Here we further exploit distinctive features of yeast for this purpose.Methods for serially replacing genomic regions with selectable markers are limited by the number of available markers. One effective approach is to reuse the same marker after precise and scarless marker excision (Storici et al. 2001). We have previously used a self-excising marker (Noskov et al. 2010) six times in yeast to generate a JCVI-syn1.0 genome lacking all six restriction systems (JCVI-syn1.0 ∆1-6) (Karas et al. 2013a). Despite the advantages of scarless engineering, sequential procedures are time-consuming. When applied to poorly characterized genes with the potential to interact with other genes, some paths for multigene knockout may lead to dead ends that result from synergistic mutant phenotypes. When a dead end is reached, sequentially returning to a previous genome in an effort to find a detour to a viable higher-order multimutant may be prohibitively time-consuming.An alternative approach to multigene engineering, available in yeast, is to prepare a set of single mutants and combine the deletions into a single strain via cycles of mating and meiotic recombination (Fig. 1A; Pinel et al. 2011; Suzuki et al. 2011, 2012). With a green fluorescent protein (GFP) reporter gene inserted in each deletion locus, the enrichment of higher-order yeast deletion strains in the meiotic population can be accomplished using flow cytometry. Here we apply this method to the JCVI-syn1.0 ∆1-6 exogenous, bacterial genome harbored in yeast to nonsequentially assemble deletions for genes predicted to be individually deletable based on biological knowledge or transposon-mediated disruption data. The functional identification of simultaneously deletable regions is expected to accelerate the effort to construct a minimal genome.Open in a separate windowFigure 1.Progressive clustering of deleted genomic segments. (A) Scheme of the method. Light blue oval represents a bacterial cell. Black ring or horizontal line denotes a bacterial genome, with the orange box indicating the yeast vector used as a site for linearization and recircularization. Gray shape denotes a yeast cell. Green dot in the genome indicates a deletion replaced with a GFP marker. (B) Map of deleted regions. Orange box indicates the yeast vector sequence used for genome linearization and recircularization. Green boxes indicate regions deleted in multimutant mycoplasma strains. Blue boxes denote restriction modification (RM) systems that are also deleted in the strains. (C) Pulsed-gel electrophoresis result for deleted genomes. The starting strain was the JCVI-syn1.0 ∆1–6 strain (1062 kb). Two strains were analyzed for each design of simultaneous deletion (962 kb for eight-deletion or 974 kb for seven-deletion genome). Ladder is a set of yeast chromosomes (New England BioLabs). (D) GFP-RFP ratio sorting result. Standard sorting was compared with sorting based on a GFP-RFP ratio (Methods).     

The Ethical,Legal and Human Rights Concerns Raised by Licensing HIV Self-Testing for Private Use

We argue that there are no compelling ethical grounds for not allowing the sale of HIV self-tests to the public, so long as reasonably robust protections are in place to protect against coerced testing, and so long as the ease of use of the test is validated carefully in each country in which it is used, with attention to information about linkage to treatment, social and psychological support. The tests are not likely to be harmful in a way that justifies restricting people’s access to them, and have plausible benefits. Whether and how self-testing should be used in public health programs will depend on complex policy questions concerning priorities, efficacy and cost.     

Role of stem cell factor and granulocyte colony-stimulating factor in remodeling during liver regeneration

Functional pluripotent characteristics have been observed in specific subpopulations of hepatic cells that express some of the known cholangiocyte markers. Although evidence indicates that specific cytokines, granulocyte macrophage colony-stimulating factors (GM-CSFs), and stem cell factors (SCFs) may be candidate treatments for liver injury, the role of these cytokines in intrahepatic biliary epithelium remodeling is unknown. Thus, our aim was to characterize the specific cytokines that regulate the remodeling potentials of cholangiocytes after 70% partial hepatectomy (PH). The expression of the cytokines and their downstream signaling molecules was studied in rats after 70% PH by immunoblotting and in small and large murine cholangiocyte cultures (SMCCs and LMCCs) by immunocytochemistry and real-time polymerase chain reaction (PCR). There was a significant, stable increase in SCF and GM-CSF levels until 7 days after PH. Real-time PCR analysis revealed significant increases of key remodeling molecules, such as S100 calcium-binding protein A4 (S100A4) and miR-181b, after SCF plus GM-CSF administration in SMCCs. SMCCs produced significant amounts of soluble and bound SCFs and GM-CSFs in response to transforming growth factor-beta (TGF-β). When SMCCs were incubated with TGF-β plus anti-SCF+GM-CSF antibodies, there was a significant decrease in S100A4 expression. Furthermore, treatment of SMCCs with SCF+GM-CSF significantly increased matrix metalloproteinases (MMP-2 and MMP-9) messenger RNA as well as miR-181b expression, along with a reduction of metalloproteinase inhibitor 3. Levels of MMP-2, MMP-9, and miR-181b were also up-regulated in rat liver and isolated cholangiocytes after PH. CONCLUSION: Our data suggest that altered expression of SCF+GM-CSF after PH can contribute to biliary remodeling (e.g., post-transplantation) by functional deregulation of the activity of key signaling intermediates involved in cell expansion and multipotent differentiation.     

Molecular comparison of alpha 1- and alpha 2-adrenergic receptors suggests that these proteins are structurally related "isoreceptors".

The structures of human platelet alpha 2-adrenergic receptors and rat liver alpha 1-adrenergic receptors were compared by utilizing isoelectric focusing, NaDodSO4/PAGE, and monoclonal antibody crossreactivity. Digitonin-solubilized alpha 1- and alpha 2-adrenergic receptors have an identical isoelectric point of 4.6. Under reducing conditions in NaDodSO4/polyacrylamide gels, the alpha 1-adrenergic receptor has an apparent molecular mass of 85 kDa. Similarly, the alpha 2-adrenergic receptor, which had been affinity-labeled with [3H]phenoxybenzamine and partially purified by isoelectric focusing or photoaffinity-labeled with p-[3,5-3H]azidoclonidine, was also found to have an apparent molecular mass of 85 kDa. One hybridoma, developed from a fusion between SP2/O myeloma cells and splenic lymphocytes from BALB/c mice immunized with human platelet alpha 2-adrenergic receptors, secreted a monoclonal antibody (alpha 2-116p) against the ligand binding site of alpha 2-adrenergic but not alpha 1-adrenergic receptors. In contrast, three monoclonal antibodies raised against the alpha 1-receptor polypeptide backbone but not the ligand binding site were found to specifically immunoprecipitate human platelet alpha 2-adrenergic receptors. These data suggest that the alpha 1- and alpha 2-adrenergic receptors are "isoreceptors," sharing immunogenic and, by implication, structural determinants that most likely evolved as a result of gene duplication.     

Diagnosis and management of Non-IgE gastrointestinal allergies in breastfed infants—An EAACI Position Paper

It is well-established that food proteins, such as egg, soya, cow's milk and wheat, are detectable in breastmilk for many hours or days after ingestion. Exposure to these proteins is important to the process of developing tolerance but can also sometimes elicit IgE-mediated and non–IgE-mediated allergic symptoms in breastfed infants. Non–IgE-mediated allergy, outside of food protein-induced allergic proctocolitis and eosinophilic oesophagitis, is not well understood, leading to variations in the diagnosis and management thereof. A primary objective of the European Academy for Allergy and Clinical Immunology is to support breastfeeding in all infants, including those with food allergies. A Task Force was established, to explore the clinical spectrum of non–IgE-mediated allergies, and part of its objectives was to establish diagnosis and management of non–IgE-mediated allergies in breastfed infants. Eight questions were formulated using the Patient, Intervention, Comparison, Outcome (PICO) system and Scottish Intercollegiate Guideline Network (SIGN) criteria for data inclusion, and consensus was achieved on practice points through the Delphi method. This publication aims to provide a comprehensive overview on this topic with practice points for healthcare professionals.