Receptor-binding profiles of H7 subtype influenza viruses in different host species

Influenza viruses of gallinaceous poultry and wild aquatic birds usually have distinguishable receptor-binding properties. Here we used a panel of synthetic sialylglycopolymers and solid-phase receptor-binding assays to characterize receptor-binding profiles of about 70 H7 influenza viruses isolated from aquatic birds, land-based poultry, and horses in Eurasia and America. Unlike typical duck influenza viruses with non-H7 hemagglutinin (HA), all avian H7 influenza viruses, irrespective of the host species, displayed a poultry-virus-like binding specificity, i.e., preferential binding to sulfated oligosaccharides Neu5Acα2-3Galβ1-4(6-O-HSO(3))GlcNAc and Neu5Acα2-3Galβ1-4(Fucα1-3)(6-O-HSO(3))GlcNAc. This phenotype correlated with the unique amino acid sequence of the amino acid 185 to 189 loop of H7 HA and seemed to be dependent on ionic interactions between the sulfate group of the receptor and Lys193 and on the lack of sterical clashes between the fucose residue and Gln222. Many North American and Eurasian H7 influenza viruses displayed weak but detectable binding to the human-type receptor moiety Neu5Acα2-6Galβ1-4GlcNAc, highlighting the potential of H7 influenza viruses for avian-to-human transmission. Equine H7 influenza viruses differed from other viruses by preferential binding to the N-glycolyl form of sialic acid. Our data suggest that the receptor-binding site of contemporary H7 influenza viruses in aquatic and terrestrial birds was formed after the introduction of their common precursor from ducks to a new host, presumably, gallinaceous poultry. The uniformity of the receptor-binding profile of H7 influenza viruses in various wild and domestic birds indicates that there is no strong receptor-mediated host range restriction in birds on viruses with this HA subtype. This notion agrees with repeated interspecies transmission of H7 influenza viruses from aquatic birds to poultry.     

Prenylation of Rho G-Proteins: a Novel Mechanism Regulating Gene Expression and Protein Stability in Human Trabecular Meshwork Cells

Endogenous prenylation with sesquiterpene or diterpene isoprenoids facilitates membrane localization and functional activation of small monomeric GTP-binding proteins. A direct effect of isoprenoids on regulation of gene expression and protein stability has also been proposed. In this study, we determined the role of sesquiterpene or diterpene isoprenoids on the regulation of Rho G-protein expression, activation, and stability in human trabecular meshwork (TM) cells. In both primary and transformed human TM cells, limiting endogenous isoprenoid synthesis with lovastatin, a potent HMG-CoA reductase inhibitor, elicited marked increases in RhoA and RhoB mRNA and protein content. The effect of lovastatin was dose-dependent with newly synthesized inactive protein accumulating in the cytosol. Supplementation with geranylgeranyl pyrophosphate (GGPP) prevented, while inhibition of geranylgeranyl transferase-I mimicked, the effects of lovastatin on RhoA and RhoB protein content. Similarly, lovastatin-dependent increases in RhoA and RhoB mRNA expression were mimicked by geranylgeranyl transferase-I inhibition. Interestingly, GGPP supplementation selectively promoted the degradation of newly synthesized Rho proteins which was mediated, in part, through the 20S proteasome. Functionally, GGPP supplementation prevented lovastatin-dependent decreases in actin stress fiber organization while selectively facilitating the subcellular redistribution of accumulated Rho proteins from the cytosol to the membrane and increasing RhoA activation. Post-translational prenylation with geranylgeranyl diterpenes selectively facilitates the expression, membrane translocation, functional activation, and turnover of newly synthesized Rho proteins. Geranylgeranyl prenylation represents a novel mechanism by which active Rho proteins are targeted to the 20S proteasome for degradation in human TM cells.     

Variation of secondary metabolite levels in maize seedling roots induced by inoculation with Azospirillum, Pseudomonas and Glomus consortium under field conditions

Background and aims

Many plant-beneficial microorganisms can influence secondary plant metabolism, but whether these effects add up when plants are co-inoculated is unclear. This issue was assessed, under field conditions, by comparing the early impacts of seed inoculation on secondary metabolite profiles of maize at current or reduced mineral fertilization levels.

Methods

Maize seeds were inoculated singly with selected strains from bacterial genera Pseudomonas and Azospirillum or mycorrhizal genus Glomus, or with these strains combined two by two or all three together. At 16?days, maize root methanolic extracts were analyzed by RP-HPLC and secondary metabolites (phenolics, flavonoids, xanthones, benzoxazionoids, etc.) identified by LC/MS.

Results

Inoculation did not impact on plant biomass but resulted in enhanced total root surface, total root volume and/or root number in certain inoculated treatments, at reduced fertilization. Inoculation led to qualitative and quantitative modifications of root secondary metabolites, particularly benzoxazinoids and diethylphthalate. These modifications depended on fertilization level and microorganism(s) inoculated. The three selected strains gave distinct results when used alone, but unexpectedly all microbial consortia gave somewhat similar results.

Conclusions

The early effects on maize secondary metabolism were not additive, as combining strains gave effects similar to those of Glomus alone. This is the first study demonstrating and analyzing inoculation effects on crop secondary metabolites in the field.     

Nonplasmacytoid, high IFN-α-producing, bone marrow dendritic cells

Plasmacytoid dendritic cells (pDC) are the producers of type I IFNs in response to TLR9 ligands. However, we have found that when bone marrow is depleted of pDC, the IFN-α produced in response to TLR9 ligands is not fully removed. We assign the source of this non-pDC IFN-α as a newly described DC type. It displays the high IFN-α producing activity of pDC but to a more limited range of viruses. Unlike pDC, the novel DC display high T cell stimulation capacity. Moreover, unlike mouse pDC, they are matured with GM-CSF and are less prone to apoptosis upon activation stimuli, including viruses. We propose that these DC constitute a novel bone marrow inflammatory DC type, ideally geared to linking innate and adaptive immune responses in bone marrow via their potent IFN-α production and high T cell stimulatory capacity.     

Glucokinase activation repairs defective bioenergetics of islets of Langerhans isolated from type 2 diabetics

It was reported previously that isolated human islets from individuals with type 2 diabetes mellitus (T2DM) show reduced glucose-stimulated insulin release. To assess the possibility that impaired bioenergetics may contribute to this defect, glucose-stimulated respiration (Vo(2)), glucose usage and oxidation, intracellular Ca(2+), and insulin secretion (IS) were measured in pancreatic islets isolated from three healthy and three type 2 diabetic organ donors. Isolated mouse and rat islets were studied for comparison. Islets were exposed to a "staircase" glucose stimulus, whereas IR and Vo(2) were measured. Vo(2) of human islets from normals and diabetics increased sigmoidally from equal baselines of 0.25 nmol/100 islets/min as a function of glucose concentration. Maximal Vo(2) of normal islets at 24 mM glucose was 0.40 ± 0.02 nmol·min(-1)·100 islets(-1), and the glucose S(0.5) was 4.39 ± 0.10 mM. The glucose stimulation of respiration of islets from diabetics was lower, V(max) of 0.32 ± 0.01 nmol·min(-1)·100 islets(-1), and the S(0.5) shifted to 5.43 ± 0.13 mM. Glucose-stimulated IS and the rise of intracellular Ca(2+) were also reduced in diabetic islets. A clinically effective glucokinase activator normalized the defective Vo(2), IR, and free calcium responses during glucose stimulation in islets from type 2 diabetics. The body of data shows that there is a clear relationship between the pancreatic islet energy (ATP) production rate and IS. This relationship was similar for normal human, mouse, and rat islets and the data for all species fitted a single sigmoidal curve. The shared threshold rate for IS was ～13 pmol·min(-1)·islet(-1). Exendin-4, a GLP-1 analog, shifted the ATP production-IS curve to the left and greatly potentiated IS with an ATP production rate threshold of ～10 pmol·min(-1)·islet(-1). Our data suggest that impaired β-cell bioenergetics resulting in greatly reduced ATP production is critical in the molecular pathogenesis of type 2 diabetes mellitus.     

Erythropoietin attenuates neurological and histological consequences of toxic demyelination in mice

Erythropoietin (EPO) reduces symptoms of experimental autoimmune encephalomyelitis in rodents and shows neuroregenerative effects in chronic progressive multiple sclerosis. The mechanisms of action of EPO in these conditions with shared immunological etiology are still unclear. Therefore, we used a model of toxic demyelination allowing exclusion of T cell-mediated inflammation. In a double-blind (for food/injections), placebo-controlled, longitudinal four-arm design, 8-wk-old C57BL/6 mice (n = 26/group) were assigned to cuprizone-containing (0.2%) or regular food (ground chow) for 6 wks. After 3 wks, mice were injected every other day with placebo or EPO (5,000 IU/kg intraperitoneally) until the end of cuprizone feeding. Half of the mice were exposed to behavioral testing, magnetic resonance imaging (MRI) and histology immediately after treatment cessation, whereas the other half were allowed a 3-wk treatment-free recovery. Immediately after termination of cuprizone feeding, all toxin-exposed mice were compromised regarding vestibulomotor function/coordination, with EPO-treated animals performing better than placebo. Likewise, ventricular enlargement after cuprizone, as documented by MRI, was less pronounced upon EPO. After a 3-wk recovery, remarkable spontaneous improvement was observed in all mice with no measurable further benefit in the EPO group ("ceiling effect"). Histological analysis of the corpus callosum revealed attenuation by EPO of the cuprizone-induced increase in microglial numbers and amyloid precursor protein accumulations as a readout of inflammation and axonal degeneration. To conclude, EPO ameliorates neurological symptoms in the cuprizone model of demyelination, possibly by reduction of inflammation-associated axonal degeneration in white matter tracts. These findings underscore the value of future therapeutic strategies for multiple sclerosis based on EPO or EPO variants.     

Hog barn dust extract augments lymphocyte adhesion to human airway epithelial cells.

The dust of hog confinement facilities induces airway inflammation. Mechanisms by which this dust modulates inflammation are not completely defined, although it is clear that exposure to dust can modulate both epithelial cell and inflammatory cell function. In this work, we demonstrate that airway epithelial cell (BEAS-2B) treatment with hog barn dust extract (HDE) results in augmentation of peripheral blood lymphocyte adhesion to epithelial cell cultures in vitro. The augmentation of lymphocyte adhesion to epithelial cells is dependent on the concentration of HDE and time of HDE exposure, with twofold increases observed by 3 h and maintained at 24 h. Similar results are seen with primary human bronchial epithelial cells in culture. Lymphocyte adhesion to epithelial cells is inhibited in a concentration-dependent fashion by the treatment of epithelial cells with antibody to intercellular adhesion molecule-1 (ICAM-1). In addition, HDE exposure of epithelial cells results in an approximate twofold increase in ICAM-1 expression as determined by flow cytometry analysis. Pretreatment of epithelial cells with a protein kinase C-alpha (PKC-alpha) inhibitor, G?-6976, also inhibited subsequent lymphocyte adhesion to HDE-exposed epithelial cells. These data suggest that airway epithelial cell HDE exposure enhances subsequent lymphocyte adhesion to epithelial cells that is mediated in part by HDE modulation of ICAM-1 expression and PKC-alpha.     

Meal Frequency and Childhood Obesity

Objective: Previous studies have demonstrated an inverse association between meal frequency and the prevalence of obesity in adulthood. The aim of this study was to assess the relationship between meal frequency and childhood obesity. Research Methods and Procedures: Stature and weight of 4370 German children ages 5 to 6 years were determined in six Bavarian (Germany) public health offices during the obligatory school entry health examination in 2001/2002. An extensive questionnaire on risk factors for obesity was answered by their parents. Obesity was defined according to sex‐ and age‐specific BMI cut‐off points proposed by the International Obesity Task Force. The main exposure was daily meal frequency. Results: The prevalence of obesity decreased by number of daily meals: three or fewer meals, 4.2% [95% confidence interval (CI), 2.8 to 6.1]; four meals, 2.8% (95% CI, 2.1 to 3.7); and 5 or more meals, 1.7% (95% CI, 1.2 to 2.4). These effects could not be explained by confounding due to a wide range of constitutional, sociodemographic, and lifestyle factors. The adjusted odds ratios for obesity were 0.73 (95% CI, 0.44 to 1.21) for four meals and 0.51 (95% CI, 0.29 to 0.89) for five or more meals. Additional analyses pointed to a higher energy intake in nibblers compared with gorgers. Discussion: A protective effect of an increased daily meal frequency on obesity in children was observed and appeared to be independent of other risk factors for childhood obesity. A modulation of the response of hormones such as insulin might be instrumental.