Pandinus imperator scorpion venom blocks voltage-gated potassium channels in GH3 cells

We examined the effects of Pandinus imperator scorpion venom on voltage-gated potassium channels in cultured clonal rat anterior pituitary cells (GH3 cells) using the gigohm-seal voltage-clamp method in the whole-cell configuration. We found that Pandinus venom blocks the voltage-gated potassium channels of GH3 cells in a voltage-dependent and dose-dependent manner. Crude venom in concentrations of 50-500 micrograms/ml produced 50-70% block of potassium currents measured at -20 mV, compared with 25-60% block measured at +50 mV. The venom both decreased the peak potassium current and shifted the voltage dependence of potassium current activation to more positive potentials. Pandinus venom affected potassium channel kinetics by slowing channel opening, speeding deactivation slightly, and increasing inactivation rates. Potassium currents in cells exposed to Pandinus venom did not recover control amplitudes or kinetics even after 20-40 min of washing with venom-free solution. The concentration dependence of crude venom block indicates that the toxins it contains are effective in the nanomolar range of concentrations. The effects of Pandinus venom were mimicked by zinc at concentrations less than or equal to 0.2 mM. Block of potassium current by zinc was voltage dependent and resembled Pandinus venom block, except that block by zinc was rapidly reversible. Since zinc is found in crude Pandinus venom, it could be important in the interaction of the venom with the potassium channel. We conclude that Pandinus venom contains toxins that bind tightly to voltage-dependent potassium channels in GH3 cells. Because of its high affinity for voltage-gated potassium channels and its irreversibility, Pandinus venom may be useful in the isolation, mapping, and characterization of voltage-gated potassium channels.     

Whole Grain Intakes in the Diets Of Malaysian Children and Adolescents – Findings from the MyBreakfast Study

Background

Diets rich in whole grain are associated with several health benefits. Little is known however, about whole grain consumption patterns in Malaysia. The aim of this study was to assess whole grain intakes and dietary source in Malaysian children and adolescents.

Methods

This analysis is from the MyBreakfast study, a national cross sectional study investigating eating habits among primary and secondary school children throughout Malaysia, conducted in 2013. Children (n = 5,165) and adolescents (n = 2,947) who completed two days of dietary assessment using a food record or recall respectively were included. The whole grain content of foods was estimated mainly through the use of quantitative ingredient declarations on food labels. All wholegrain foods were considered irrespective of the amount of whole grain they contained.

Results

Overall, only 25% of children and 19% of adolescents were wholegrain consumers. Mean daily intakes in the total sample were 2.3g/d (SD 5.8g/d) in children and 1.7g/d (SD 4.7g/d) in adolescents and in the consumer’s only sample, mean intakes reached 9.1g/d (SD 8.6) and 9.2g/d (SD 7.1g/d) respectively. Wheat was the main grain source of whole grain while ready to eat breakfast cereals and hot cereals were the main food contributors. Less than 3% of the children and adolescents reached the US quantitative whole grain recommendation of 48g/day.

Conclusion

Whole grain is consumed by only a minority of Malaysian children and adolescents and even among consumers, intakes are well below recommendations. Efforts are needed to firstly understand the barriers to whole grain consumption among Malaysian children in order to design effective health promotion initiatives to promote an increase in whole grain consumption.     

Bleomycin Induces Molecular Changes Directly Relevant to Idiopathic Pulmonary Fibrosis: A Model for “Active” Disease

The preclinical model of bleomycin-induced lung fibrosis, used to investigate mechanisms related to idiopathic pulmonary fibrosis (IPF), has incorrectly predicted efficacy for several candidate compounds suggesting that it may be of limited value. As an attempt to improve the predictive nature of this model, integrative bioinformatic approaches were used to compare molecular alterations in the lungs of bleomycin-treated mice and patients with IPF. Using gene set enrichment analysis we show for the first time that genes differentially expressed during the fibrotic phase of the single challenge bleomycin model were significantly enriched in the expression profiles of IPF patients. The genes that contributed most to the enrichment were largely involved in mitosis, growth factor, and matrix signaling. Interestingly, these same mitotic processes were increased in the expression profiles of fibroblasts isolated from rapidly progressing, but not slowly progressing, IPF patients relative to control subjects. The data also indicated that TGFβ was not the sole mediator responsible for the changes observed in this model since the ALK-5 inhibitor SB525334 effectively attenuated some but not all of the fibrosis associated with this model. Although some would suggest that repetitive bleomycin injuries may more effectively model IPF-like changes, our data do not support this conclusion. Together, these data highlight that a single bleomycin instillation effectively replicates several of the specific pathogenic molecular changes associated with IPF, and may be best used as a model for patients with active disease.     

How old is this mutation? - a study of three Ashkenazi Jewish founder mutations

Background

Several founder mutations leading to increased risk of cancer among Ashkenazi Jewish individuals have been identified, and some estimates of the age of the mutations have been published. A variety of different methods have been used previously to estimate the age of the mutations. Here three datasets containing genotype information near known founder mutations are reanalyzed in order to compare three approaches for estimating the age of a mutation. The methods are: (a) the single marker method used by Risch et al., (1995); (b) the intra-allelic coalescent model known as DMLE, and (c) the Goldgar method proposed in Neuhausen et al. (1996), and modified slightly by our group. The three mutations analyzed were MSH2*1906 G->C, APC*I1307K, and BRCA2*6174delT.

Results

All methods depend on accurate estimates of inter-marker recombination rates. The modified Goldgar method allows for marker mutation as well as recombination, but requires prior estimates of the possible haplotypes carrying the mutation for each individual. It does not incorporate population growth rates. The DMLE method simultaneously estimates the haplotypes with the mutation age, and builds in the population growth rate. The single marker estimates, however, are more sensitive to the recombination rates and are unstable. Mutation age estimates based on DMLE are 16.8 generations for MSH2 (95% credible interval (13, 23)), 106 generations for I1037K (86-129), and 90 generations for 6174delT (71-114).

Conclusions

For recent founder mutations where marker mutations are unlikely to have occurred, both DMLE and the Goldgar method can give good results. Caution is necessary for older mutations, especially if the effective population size may have remained small for a long period of time.

     

Functional normalization of 450k methylation array data improves replication in large cancer studies

We propose an extension to quantile normalization that removes unwanted technical variation using control probes. We adapt our algorithm, functional normalization, to the Illumina 450k methylation array and address the open problem of normalizing methylation data with global epigenetic changes, such as human cancers. Using data sets from The Cancer Genome Atlas and a large case–control study, we show that our algorithm outperforms all existing normalization methods with respect to replication of results between experiments, and yields robust results even in the presence of batch effects. Functional normalization can be applied to any microarray platform, provided suitable control probes are available.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-014-0503-2) contains supplementary material, which is available to authorized users.     

Macrophage deformability and phagocytosis

The influence of several metabolic inhibitors and pharmacologic agents on macrophage deformation (induced by fluid shear stress) was examined in relationship to changes in ATP content and phagocytosis of latex beads. Two relatively specific inhibitors of glycolysis (iodoacetate [IA], and sodium fluoride [NaF]) and a sulfhydryl-binding agent (N-ethylmaleimide [NEM] markedly inhibited phagocytosis and reduced cell deformability. A microtubule-disrupting agent (vinblastine) and a highly specific inhibitor of glycolysis (2-deoxyglucose) markedly inhibited phagocytosis without influencing cell deformability. An organomercurial sulfhydryl binding agent p-chloromercuribenzene (PCMBS) and a microfilament-disrupting agent (cytochalasin B) inhibited phagocytosis and increased cell deformability. The effects of these agents on phagocytosis and cell deformability bore no consistent relationship to alterations in cellular content of ATP. The observation that 2-deoxyglucose, the most specific inhibitor of glycolysis examined, reduced ATP content to levels far lower (15 percent of control values) than those achieved by any other agent examined and inhibited phagocytosis without altering cell deformability, suggests that alterations in cell deformability induced by NaF, IA, NEM, PCMBS, and cytochalasin B are not due to inhibition of glycolysis per se, but instead result from direct or indirect effects of these agents on cell constituents, possibly contractile proteins, which are determinants of cell deformability. The finding that cytochalasin B, NEM, PCMBS, and IA interfere with phagocytosis and alter cell deformability, together with evidence that these agents interact with isolated actin and myosin, suggests that contractile proteins are important both in phagocytosis and as determinants of cell deformability. The observation that vinblastine, colchicines, and heavy water (D(2)O) did not alter cell deformability, even though vinblastine caused formation of intracellular crystals of microtubular protein, indicates that microtubules are not major determinants of cell deformability. The observations that beads adhered normally to surfaces of cytochalasin B- and of PCMBS-treated cells and that shear-stress induced deformation was increased whereas phagocytosis was markedly inhibited, suggest that deformation of cells around beads associated with ingestion depends on some form of cellular (contractile?) activity, whereas deformation of cells by fluid shear stress is a passive phenomenon.     

Cigarette smoke-induced accumulation of lung dendritic cells is interleukin-1α-dependent in mice

Background

Evidence suggests that dendritic cells accumulate in the lungs of COPD patients and correlate with disease severity. We investigated the importance of IL-1R1 and its ligands IL-1α and β to dendritic cell accumulation and maturation in response to cigarette smoke exposure.

Methods

Mice were exposed to cigarette smoke using a whole body smoke exposure system. IL-1R1-, TLR4-, and IL-1α-deficient mice, as well as anti-IL-1α and anti-IL-1β blocking antibodies were used to study the importance of IL-1R1 and TLR4 to dendritic cell accumulation and activation.

Results

Acute and chronic cigarette smoke exposure led to increased frequency of lung dendritic cells. Accumulation and activation of dendritic cells was IL-1R1/IL-1α dependent, but TLR4- and IL-1β-independent. Corroborating the cellular data, expression of CCL20, a potent dendritic cells chemoattractant, was IL-1R1/IL-1α-dependent. Studies using IL-1R1 bone marrow-chimeric mice revealed the importance of IL-1R1 signaling on lung structural cells for CCL20 expression. Consistent with the importance of dendritic cells in T cell activation, we observed decreased CD4⁺ and CD8⁺ T cell activation in cigarette smoke-exposed IL-1R1-deficient mice.

Conclusion

Our findings convey the importance of IL-1R1/IL-1α to the recruitment and activation of dendritic cells in response to cigarette smoke exposure.