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The Drosophila trithorax group gene kismet (kis) was identified in a screen for extragenic suppressors of Polycomb (Pc) and subsequently shown to play important roles in both segmentation and the determination of body segment identities. One of the two major proteins encoded by kis (KIS-L) is related to members of the SW12/SNF2 and CHD families of ATP-dependent chromatin-remodeling factors. To clarify the role of KIS-L in gene expression, we examined its distribution on larval salivary gland polytene chromosomes. KIS-L is associated with virtually all sites of transcriptionally active chromatin in a pattern that largely overlaps that of RNA Polymerase II (Pol II). The levels of elongating Pol II and the elongation factors SPT6 and CHD1 are dramatically reduced on polytene chromosomes from kis mutant larvae. By contrast, the loss of KIS-L function does not affect the binding of PC to chromatin or the recruitment of Pol II to promoters. These data suggest that KIS-L facilitates an early step in transcriptional elongation by Pol II. [ABSTRACT FROM AUTHOR]

Twofold differences in gene expression levels can be vital for an organism. This is beautifully illustrated by the process of `dosage compensation'' in Drosophila, which doubles transcription from the single male X chromosome to equal the mRNA levels originating from the two X chromosomes in female cells. Failure of the process leads to male-specific lethality. A number of recent publications have furthered our understanding of the ribonucleoprotein complex, which mediates dosage compensation and how it targets the male X chromosome. Deciphering the principles of X chromosome recognition and the nature of the chromatin configuration, that allows fine-tuning of transcription, remain the most interesting challenges. [Copyright &y& Elsevier]

The effects of theaflavin digallate, a main component of black tea theaflavins; epigallocatechin gallate, a main component of green tea catechins; and polyphenol extract, containing an OTP trimer as a major component of oolong tea, was tested on human colon cancer COLO 205 cells and normal lymphocytes. Treatment with theaflavin digallate, epigallocatechin, and polyphenol extract resulted in growth inhibition and induced apoptosis in the COLO 205 cells, but not in normal human lymphocytes. Morphological examination of the tissue showed apoptotic bodies in cells treated with the chemical compounds. DNA fragmentation and the formation of oligonucleosomal-sized fragments in treated cells, characteristic of apoptosis, were concentration and time dependent. The data provide the first evidence that tea extracts induce apoptosis in human colon cancer cells. [ABSTRACT FROM AUTHOR]

Background: Little information is available on the relative contribution of peptide growth factors and leukocyte-derived proteinases to the repair processes in inflammatory bowel disease (IBD). We investigated their possible roles in epithelial cell restitution and proliferation in patients with IBD.Methods: The expression of hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), transforming growth factor-beta (TGF-beta), and neutrophil elastase (NE) was examined in colonic mucosal tissues. The effects of organ culture supernatants of mucosal tissues on epithelial cell restitution and proliferation were analyzed in vitro using an intestinal cell line, IEC-6 cells.Results: Most organ cultures detected the presence of measurable levels of HGF, with a relative paucity of KGF and TGF-beta activity. Greater levels of HGF were obtained in the mucosa involved with IBD, especially in patients with ulcerative colitis (UC). The mucosa involved with UC also showed higher amounts of NE. The supernatants from the mucosa involved with UC possessed a prominent stimulatory effect on the restitution of IEC-6 cells. By contrast, significant suppression beyond baseline levels was observed for the proliferation of IEC-6 cells when they were incubated with recombinant HGF plus the supernatants from the mucosa involved with UC. This suppression was diminished considerably by preincubation of the supernatants with the anti-NE antibody.Conclusions: HGF produced in the intestinal mucosa may be an important stimulator acting on epithelial cell restitution in patients with IBD. However, NE released in situ may impair mucosal repair through inhibiting epithelial cell proliferation in patients with UC. [ABSTRACT FROM AUTHOR]

Background: Clarithromycin (CAM) may have certain indirect effects on Helicobacter pylori (H. pylori ) other than its inhibitory activity on bacterial growth, as indicated in other infections with Gram-negative micro-organisms. In the present study, we examined the effects of lower concentrations of CAM on the release of heat shock protein B (HspB), one of the major antigenic proteins from H. pylori cells, as well as the changes in humoral immune response and histological degree of antral gastritis in patients who received eradication therapy with CAM. Methods: The H. pylori strain 26695 and three CAM-resistant clinical isolates were cultured in broth with and without CAM (2–500 ng/mL). Expression of H. pylori proteins was examined by two-dimensional (2D)-electrophoresis followed by N-terminal amino acid sequencing. Changes in host immune response and histological degree of antral gastritis were monitored in patients with peptic ulcer disease who received H. pylori eradication therapy. Results: 2D electrophoresis showed 26 spots in extracellularly released proteins with different profiles from those in cytoplasmic proteins. The release of HspB increased after incubation with CAM (30–500 ng/mL) in all three H. pylori clinical isolates tested. Patients with failed H. pylori eradication after triple therapy with CAM, but not those with failed eradication after dual therapy without CAM, showed an increase in serum IgG1 and IgG2 antibodies against HspB along with a decrease in the degree of neutrophil and H. pylori colonization density in tissue sections. Conclusions: CAM may induce a humoral immune response against H. pylori and a decrease in gastric mucosal inflammation through up-regulation of the release of HspB from the bacteria in infected patients. [ABSTRACT FROM AUTHOR]

In the present study, the three-dimensional architecture of retinal vasculature was studied in KK mice, by combined use of resin injection, chemical treatment and scanning electron microscopy (SEM). In particular, Mercox/methylmethacrylate resin-injected eye tissues were subjected in sequence to NaClO immersion, ultrasonication and HCl treatment. The present technological innovation made possible SEM visualization of deeper retinal vasculature. In KK mice, the tunica media of stem arterioles and of first and second order branches consisted of a single layer of spindle-shaped smooth muscle cells provided with spine-like cytoplasmic processes. In addition, there occurred small triangular smooth muscle cells provided with slender cytoplasmic processes. The processes, giving off tiny secondary processes, overlapped with each other, thus forming assemblages around branching sites. Such a structure was particularly prominent for those branching sites where parent arterioles gave rise to their branches in a side arm-like pattern. The third (and occasionally fourth) order branche were surrounded by atypical smooth muscle, cells, with considerable dimension of endothelial surface remaining uncovered. Capillary pericytes consisted of fusiform cell bodies and slender cytoplasmic processes. Smooth muscle cells of retinal venules differed from those of arterioles. They were stellate in shape, exhibiting several cytoplasmic processes. [ABSTRACT FROM PUBLISHER]

Background: Although increased levels of interleukin (IL)-8 are known to be associated with infiltration of neutrophils in the gastric mucosa with Helicobacter pylori infection, no study has investigated the relationship between local IL-8 levels and neutrophil infiltration in the duodenal mucosa of patients with duodenal ulcer (DU). Methods: Duodenal mucosal biopsy specimens with and without gastric metaplasia (GM) were obtained from patients with DU and controls with an endoscopic methylene blue (MB) staining method. Levels of IL-8 secreted in the organ cultures of biopsy specimens were measured with an enzyme-linked immunosorbent assay. The number of myeloperoxidase-positive neutrophils infiltrating the lamina propria was determined in immunohistochemically stained tissue sections. Results: Histologic assessment showed that there was a strong correlation between the absence of endoscopic MB staining and the extent of GM. The levels of IL-8 in both duodenal and antral mucosal tissues were significantly higher in patients with H. pylori infection than in those without infection. In patients with DU the duodenal mucosal tissues with GM (MB-unstained mucosa) showed significantly higher levels of IL-8 than those without GM (MB-stained mucosa) or the antral mucosa. The number of neutrophils showed similar variations among DU and control patients with a positive correlation with IL-8 activity. The levels of IL-8 and the number of neutrophils decreased after H. pylori eradication in both duodenal and antral mucosal tissues, and these changes were more remarkable in the duodenal mucosal tissues with GM. Conclusions: Increased IL-8 activity in the duodenal mucosa with GM may be important for ulcerogenesis in H. pylori-positive DU patients. [ABSTRACT FROM AUTHOR]

We have cloned a 13 kb Escherichia coli DNA fragment which complemented the rfe mutation to recover the biosynthesis of E. coli O9 polysaccharide. Using Tn5 insertion inactivation, the rfe gene was localized at the 1.5kb HindIII-EcoRI region flanking the rho gene. We constructed an rfe-deficient E. coli K-12 mutant by site-directed inactivation using a DNA fragment of the cloned 1.5 kb rfe gene. This also confirmed the presence of the rfe gene in the 1.5kb region. By simultaneous introduction of both the rfe plasmid and the plasmid of our previously cloned E. coli 09 rfb into this rfe mutant, we succeeded in achieving in vivo reconstitution of O9 polysaccharide biosynthesis. From sequence analysis of the rfe gene, a putative promoter followed by an open reading frame (ORF) was identified downstream of the rho gene. This ORF coincided with the position of the rfe gene determined by Tn5 analysis and site-directed mutagenesis. Furthermore, we identified the rff genes in the 10.5kb DNA flanking the rfe gene. We recognized at least two functional domains on this cloned rff region. Region I complemented a newly found K-12 rff mutant, A238, to synthesize the enterobacterial common antigen (ECA). Deletion of region II resulted in the synthesis of ECAs with shorter sugar chains. When the 10.5kb rff genes of the plasmid were inactivated by either deletion or Tn5 insertion, the plasmid lost its ability to give rise to transformants of the rfe mutants. [ABSTRACT FROM AUTHOR]