Effect of ATP-sensitive K+ channel regulators on cystic fibrosis transmembrane conductance regulator chloride currents.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a Cl- channel that is regulated by cAMP-dependent phosphorylation and by intracellular ATP. Intracellular ATP also regulates a class of K+ channels that have a distinct pharmacology: they are inhibited by sulfonylureas and activated by a novel class of drugs called K+ channel openers. In search of modulators of CFTR Cl- channels, we examined the effect of sulfonylureas and K+ channel openers on CFTR Cl- currents in cells expressing recombinant CFTR. The sulfonylureas, tolbutamide and glibenclamide, inhibited whole-cell CFTR Cl- currents at half-maximal concentrations of approximately 150 and 20 microM, respectively. Inhibition by both agents showed little voltage dependence and developed slowly; > 90% inhibition occurred 3 min after adding 1 mM tolbutamide or 100 microM glibenclamide. The effect of tolbutamide was reversible, while that of glibenclamide was not. In contrast to their activating effect on K+ channels, the K+ channel openers, diazoxide, BRL 38227, and minoxidil sulfate inhibited CFTR Cl- currents. Half-maximal inhibition was observed at approximately 250 microM diazoxide, 50 microM BRL 38227, and 40 microM minoxidil sulfate. The rank order of potency for inhibition of CFTR Cl- currents was: glibenclamide < BRL 38227 approximately equal to minoxidil sulfate > tolbutamide > diazoxide. Site-directed mutations of CFTR in the first membrane-spanning domain and second nucleotide-binding domain did not affect glibenclamide inhibition of CFTR Cl- currents. However, when part of the R domain was deleted, glibenclamide inhibition showed significant voltage dependence. These agents, especially glibenclamide, which was the most potent, may be of value in identifying CFTR Cl- channels. They or related analogues might also prove to be of value in treating diseases such as diarrhea, which may involve increased activity of the CFTR Cl- channel.     

MHC class II sequences of an HLA-DR2 narcoleptic

Narcolepsy has a 98% association with the DR2-Dw2/DQw1 haplotype. To establish if a disease-specific allele is present in narcolepsy, a cDNA library was made from a B-cell line from a DR2,4/DQw1,3 narcoleptic. Clones encoding the two expressed DR2 chains, along with DQw1 and chains, were isolated and completely sequenced. The coding regions of these four genes were similar to published nucleotide and protein sequences from corresponding healthy controls, with some minor exceptions. The 3 untranslated region of one of the DR2 genes in the narcoleptic was extended by 42 bp. Complete sequences were not available for DQw1.2 or from healthy individuals, but first domain nucleotide sequences showed only a single nonproductive difference in DQ. Partial protein sequences of both DQ and from published data were identical. Although the effects of minor differences cannot be ruled out completely, it is concluded that there are probably no narcolepsy-specific DR or DQ / sequences, and that the alleles found in narcolepsy are representative of those found in the healthy population.     

Ion transport by primary cultures of canine tracheal epithelium: Methodology,morphology, and electrophysiology

Summary Canine tracheal epithelial cells were isolated by enzymatic and mechanical dispersion and cultured on permeable supports. The cells formed confluent monolayers and retained most of the morphologic characteristics of the intact epithelium, including apical microvilli, apical tight junctions, and a moderately interdigitated lateral intercellular space. The cells also retained the functional properties of the epithelium. The monolayer responded to addition of isoproterenol with the characteristic changes in cellular electrical properties expected for stimulation of Cl secretion: isoproterenol increased transepithelial voltage, depolarized apical membrane voltage, and decreased both transepithelial resistance and the ratio of apical-to-basolateral membrane resistance. Examination of the cellular response to ion substitutions and inhibitors of Cl secretion indicate that the cultured monolayers retain the same cellular mechanisms of ion transport as the intact epithelium. Thus, primary cultures of tracheal epithelium may provide a useful preparation for future studies of the mechanism and regulation of Cl secretion by airway epithelia.     

Antibiotic-Resistant Genes and Pathogens Shed by Wild Deer Correlate with Land Application of Residuals

The purpose of this study was to investigate genetic biomarkers of zoonotic enteric pathogens and antibiotic-resistant genes (ARGs) in the feces of white-tailed deer (Odocoileus virginianus) as related to proximity of deer to land that receives livestock manure or human waste biosolid fertilizers. Deer feces were collected in the St. Lawrence River Valley and Adirondack State Park of New York. Campylobacter spp. 16S rDNA was detected in 12 of 232 fecal samples (8 of 33 sites). Salmonellae were cultivated from 2 of 182 fecal samples (2 of 29 sites). Genetic virulence markers for Shiga-like toxin I (stx₁) and enterohemolysin (hylA) were each detected in one isolate of Escherichia coli; E. coli O157 was not detected in any of 295 fecal samples. ARGs detected in deer feces included ermB (erythromycin-resistant gene; 9 of 295 fecal samples, 5 of 38 sites), vanA (vancomycin-resistant gene; 93 of 284 samples, 33 of 38 sites), tetQ (tetracycline-resistant gene; 93 of 295 samples, 25 of 38 sites), and sul(I) (sulfonamide-resistant gene; 113 of 292 samples, 28 of 38 sites). Genetic markers of pathogens and ARGs in deer feces were spatially associated with collection near concentrated animal feeding operations (CAFOs; Campylobacter spp., tetQ, and ermB) and land-applied biosolids (tetQ). These results indicate that contact with human waste biosolids or animal manure may be an important method of pathogen and ARG transmission and that deer in proximity to land-applied manure and human waste biosolids pose increased risk to nearby produce and water quality.     

DNA microarray data imputation and significance analysis of differential expression

MOTIVATION: Significance analysis of differential expression in DNA microarray data is an important task. Much of the current research is focused on developing improved tests and software tools. The task is difficult not only owing to the high dimensionality of the data (number of genes), but also because of the often non-negligible presence of missing values. There is thus a great need to reliably impute these missing values prior to the statistical analyses. Many imputation methods have been developed for DNA microarray data, but their impact on statistical analyses has not been well studied. In this work we examine how missing values and their imputation affect significance analysis of differential expression. RESULTS: We develop a new imputation method (LinCmb) that is superior to the widely used methods in terms of normalized root mean squared error. Its estimates are the convex combinations of the estimates of existing methods. We find that LinCmb adapts to the structure of the data: If the data are heterogeneous or if there are few missing values, LinCmb puts more weight on local imputation methods; if the data are homogeneous or if there are many missing values, LinCmb puts more weight on global imputation methods. Thus, LinCmb is a useful tool to understand the merits of different imputation methods. We also demonstrate that missing values affect significance analysis. Two datasets, different amounts of missing values, different imputation methods, the standard t-test and the regularized t-test and ANOVA are employed in the simulations. We conclude that good imputation alleviates the impact of missing values and should be an integral part of microarray data analysis. The most competitive methods are LinCmb, GMC and BPCA. Popular imputation schemes such as SVD, row mean, and KNN all exhibit high variance and poor performance. The regularized t-test is less affected by missing values than the standard t-test. AVAILABILITY: Matlab code is available on request from the authors.     

Genomic fingerprinting using arbitrarily primed PCR and a matrix of pairwise combinations of primers.

Polymorphisms in genomic fingerprints generated by arbitrarily primed PCR (AP-PCR) can distinguish between slightly divergent strains of any organism. Single oligodeoxyribonucleotide (oligo) primers have been used to generate such fingerprints, with the same primer being present at the 5' end of both strands for every PCR product. We used three arbitrary oligos, individually and in pairs, to generate six different genomic fingerprints of the same mouse genomic DNAs. Fewer than half of the products in genomic fingerprints generated using the oligos in pairs were the same as those produced by AP-PCR using one of the three oligos alone. Thus, a few oligos could be used in a very large number of single and pairwise combinations, each producing a distinct AP-PCR fingerprint with the potential to identify new polymorphisms. For example, 50 oligos can be used in a matrix of pairwise combinations to produce 2,500 fingerprints, in which at least half the data can be expected to be unique to each pair. We demonstrate this principle by using two oligos, alone and together, to generate three sets of fingerprints and map thirteen polymorphisms in the C57BL/6J x DBA/2J set of recombinant inbred mice.     

Glucosylenamines as glycosyl acceptors: synthesis of gentiobiosylenamines.

The preparation of 2,3,4-tri-O-benzyl- (3), 2,3,4-tri-O-acetyl- (4), and 2,3,4-tri-O-benzoyl-N-(2,2-diethoxycarbonylvinyl)-6-O-trityl-beta- D-glucopyranosylamine (5) is described. The reaction of 3-5 with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide yields 2,3,4-tri-O-benzyl- (9), 2,3,4-tri-O-acetyl- (10), and 2,3,4-tri-O-benzoyl-N-(2,2-diethoxycarbonylvinyl)-6-O-(2,3,4,6-tet ra-O- acetyl-beta-D-glucopyranosyl)-beta-D-glucopyranosylamine (11), respectively. 2,3,4-Tri-O-benzyl- (6), 2,3,4-tri-O-acetyl- (7), and 2,3,4-tri-O- benzoyl-N-(2,2-diethoxycarbonylvinyl)-beta-D-glucopyranosylamine (8) are also described.     

Incidence of bacteremia in stressed and unstressed populations of the blue crab, Callinectes sapidus

The incidence of bacteremia in the blue crab, Callinectes sapidus, is reported to be in excess of 80%. Because these results have been controversial, a field study was initiated to determine the effect of commercial capture and handling stresses on the incidence and levels of infection in blue crabs. The majority (75%) of "unstressed" crabs which were captured individually and bled immediately upon removal from the water were bacteremic, with a geometric mean level of infection of 14 CFU/ml of hemolymph. Crabs collected by crab pot, confined within these pots for as long as 24 h, and sampled immediately after removal from the water had a similar mean level of infection. Crabs subjected to the stresses of commercial capture, handling, and transport showed a higher incidence of infection (91%) and a mean infection level of 46 CFU/ml. Injuries sustained by crabs during commercial handling are thought to be associated with the higher incidence of infection. Vibrio spp. were primarily responsible for progressive infections in commercially stressed crabs and were the predominant bacterial type in heavily infected crabs. Our results indicated that uninjured healthy crabs do not have sterile hemolymph but instead harbor low-level bacterial infections.     

A crucial role for the vitamin D receptor in experimental inflammatory bowel diseases

The active form of vitamin D (1,25D3) suppressed the development of animal models of human autoimmune diseases including experimental inflammatory bowel disease (IBD). The vitamin D receptor (VDR) is required for all known biologic effects of vitamin D. Here we show that VDR deficiency (knockout, KO) resulted in severe inflammation of the gastrointestinal tract in two different experimental models of IBD. In the CD45RB transfer model of IBD, CD4+/CD45RBhigh T cells from VDR KO mice induced more severe colitis than wild-type CD4+/CD45RBhigh T cells. The second model of IBD used was the spontaneous colitis that develops in IL-10 KO mice. VDR/IL-10 double KO mice developed accelerated IBD and 100% mortality by 8 wk of age. At 8 wk of age, all of the VDR and IL-10 single KO mice were healthy. Rectal bleeding was observed in every VDR/IL-10 KO mouse. Splenocytes from the VDR/IL-10 double KO mice cells transferred IBD symptoms. The severe IBD in VDR/IL-10 double KO mice is a result of the immune system and not a result of altered calcium homeostasis, or gastrointestinal tract function. The data establishes an essential role for VDR signaling in the regulation of inflammation in the gastrointestinal tract.     

The second messenger pathway for germ cell-mediated stimulation of Sertoli cells.

Treatment of cultured rat Sertoli cells with FSH or dibutyryl cAMP for 30 min resulted in phosphorylation of the same Sertoli cell proteins. Different Sertoli cell proteins were phosphorylated after calcium ionophore A23187 and 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment. A23187 stimulated the phosphorylation of hsp27, while TPA alone had no effect. TPA plus A23187 resulted in phosphorylation of a 14 kDa protein, in addition to hsp27. The effect of TPA plus A23187 was identical to that of germ cells on Sertoli cell protein phosphorylation. FSH-stimulated cAMP production by Sertoli cells was reduced by prior exposure of Sertoli cells to germ cells. The results indicate that germ cells stimulate Sertoli cells by the inositol trisphosphate/diacylglycerol mediated second messenger pathway. The results also suggest that the germ cell-activated pathway interacts within Sertoli cells to modulate Sertoli cell response to FSH.