Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Total parenteral nutrition (TPN) decreases intestinal IgA and levels of Th2 cytokines, interleukin (IL)-4, and IL-10 within the supernatants of intestinal homogenates. These cytokines are known to stimulate IgA production in vitro by cells of the gut-associated lymphoid tissue (GALT). Glutamine (GLN) supplementation of TPN normalizes GALT mass and cytokine levels. Because intestinal homogenates contain mucosa which itself is a source of cytokines, it was unclear whether cytokines change within the GALT itself. This study investigates dietary effects on IL-4 and IL-10 cytokine mRNA expression within isolated GALT lamina propria cells after lipopolysaccharide (LPS) stimulation. Prospective randomized experimental trials were used in this study. Fifty-nine mice were randomized to chow, intravenous TPN (IV-TPN), intragastric TPN (IG-TPN), complex enteral diet (CED), or 2% GLN-supplemented TPN (GLN-TPN). In experiment 1, animals were fed chow, IV-TPN, IG-TPN, or CED for 5 days and received intraperitoneal LPS (100 microg/kg BW), and then were sacrificed 1 h later. Intestine was harvested for GALT lamina propria. Total RNA was extracted from lamina propria cells and cytokine mRNA for IL-4, and IL-10 was measured by reverse transcriptase polymerase chain reaction. IgA levels of intestinal washing were also measured with ELISA. In experiment 2, mRNA for IL-4 and IL-10, and intestinal IgA levels were measured in mice fed chow, IV-TPN, or GLN-TPN as in experiment 1. Both IL-4 and IL-10 mRNA expression decreased significantly in IV-TPN mice compared to chow or CED feeding. IG-TPN resulted in IL-10 mRNA expression significantly lower than chow or CED but significantly better than IV-TPN. GLN preserved IL-4 and IL-10 mRNA levels, which correlated with intestinal IgA levels. Route and type of nutrition as well as GLN influence message for the Th2 type IgA-stimulating cytokines, IL-4 and IL-10, within the primary site of GALT IgA production, the lamina propria.
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PMID:TPN decreases IL-4 and IL-10 mRNA expression in lipopolysaccharide stimulated intestinal lamina propria cells but glutamine supplementation preserves the expression. 1130 33

Because bacterial translocation from the gut is one of the important sources of bacterial infection in acute necrotizing pancreatitis (ANP) and growth hormone (GH) has the ability to promote the intestinal epithelial proliferation, we investigated the effects of GH on bacterial translocation in a rat ANP model. ANP was induced in rats by injection of 5% sodium taurocholate into the biliopancreatic duct. The rats with ANP were treated with either human recombinant GH or placebo. Laparotomized animals without induction of ANP (sham operation [SO]) served as controls. At 24 hours after operation, blood was drawn for bacterial culture and determination of amylase, lipase, and endotoxin. Peritoneal fluid and specimens of mesenteric lymph nodes (MLN), liver, pancreas, and spleen were taken for bacterial culture by standard techniques. Intestinal mucosal permeability was assessed by measuring the movement of 125I-labeled albumin from blood to intestinal lumen. Insulin-like growth factor-1 (IGF-1) mRNA was detected in the liver and ileum by reverse transcriptase-polymerase chain reaction (RT-PCR). Morphologic changes of pancreas and ileum were also analyzed. Administration of GH significantly decreased the serum amylase, lipase activities, plasma endotoxin level, and incidence of bacterial translocation. Moreover, the survival rate of ANP rats was improved. The severity of inflammation in pancreas and ileum was alleviated by GH treatment. Ileal mucosal thickness, villus height, and crypt depth in GH treatment rats were obviously increased compared with those of ANP rats. The intestinal permeability was markedly improved in the GH group versus the ANP group. GH treatment resulted in up-regulation of IGF-1 mRNA expression in ileum, but not in liver. These results suggested that exogenous GH had beneficial effects in maintaining the integrity of intestinal mucosal barrier and reducing the incidence of bacterial translocation in rats with ANP. One of the mechanisms might be the up-regulation of IGF-1 mRNA in intestine by GH treatment.
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PMID:Beneficial effects of growth hormone on bacterial translocation during the course of acute necrotizing pancreatitis in rats. 1148 17

The cockroach-type or A-type allatostatins are inhibitory insect neuropeptides with the C-terminal sequence Tyr/Phe-X-Phe-Gly-Leu-NH(2). Here, we have cloned an A-type allatostatin receptor from the silkworm Bombyx mori (BAR). BAR is 361 amino acid residues long, has seven transmembrane domains, shows 60% amino acid residue identity with the first Drosophila allatostatin receptor (DAR-1), and 48% identity with the second Drosophila allatostatin receptor (DAR-2). The BAR gene has two introns and three exons. These two introns coincide with and have the same intron phasing as two introns in the DAR-1 and DAR-2 genes, showing that the three receptors are not only structurally but also evolutionarily related. Furthermore, we have cloned a Bombyx allatostatin preprohormone that contains eight different A-type allatostatins. Chinese hamster ovary cells permanently transfected with BAR DNA react on the addition of 4 x 10(-9)M Bombyx A-type allatostatins with a second messenger cascade (measured as bioluminescence), showing that BAR is a functional A-type allatostatin receptor. Southern blots suggest that Bombyx has at least one other BAR-related gene in addition to the BAR gene described in this paper. Northern blots and quantitative reverse transcriptase-polymerase chain reaction of different larval tissues show that BAR mRNA is mainly expressed in the gut and to a much lesser extent in the brain. To our knowledge, this is the first report on the molecular cloning and functional expression of an insect gut/brain peptide hormone receptor.
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PMID:Molecular cloning of a functional allatostatin gut/brain receptor and an allatostatin preprohormone from the silkworm Bombyx mori. 1159 Jan 50

The oral use of chewing tobacco has greatly increased in recent years, and this usage is associated with cancers of the mouth, lip, nasal cavities, esophagus and gut. Oral cancer accounts for 3% of all cancers in U.S.A. and is the seventh most common cancer. Previous studies in our laboratory have demonstrated the protective abilities of a novel IH636 grape seed proanthocyanidin extract (GSPE) against reactive oxygen species both in vitro and in vivo models, and provided significantly better protection as compared to vitamins C, E and beta-carotene. In the recent past, we have demonstrated smokeless tobacco (STE)-induced oxidative stress, apoptotic cell death in a primary culture of normal human oral keratinocytes (NHOK), and have compared the protective abilities of vitamins C and E, singly and in combination, and GSPE in this pathobiology [Free Rad. Biol. Med., 26, 992-1000 (1999)]. In the present study, we have assessed the protective role of vitamins C and E, and GSPE against STE-induced modulation of intracellular oxidized states in NHOK cells as demonstrated by laser scanning confocal microscopy. Approximately 11%, 26%, 28% and 50% protection were observed following incubation with vitamin C, vitamin E, a combination of vitamins C plus E, and GSPE, respectively. DNA fragmentation was assessed as an index of oxidative DNA damage and similar results were observed. Furthermore, the cellular viability and functional roles of Bcl-2, p53 and c-myc genes were assessed in STE-induced oxidative stress in NHOK cells. NHOK cells were treated with STE (0-200 micrograms/ml) for 24 h and changes in the expression of Bcl-2, p53 and c-myc genes were measured by reverse transcriptase-polymerase chain reaction (RT-PCR), and the protective effect of GSPE was assessed. Approximately a 2.0-fold increase in p53 gene expression was observed following incubation of the oral keratinocytes with 100 micrograms/ml of STE, beyond which the expression of p53 decreased, confirming increased apoptotic cell death with a higher concentration of STE as reported earlier. GSPE significantly modulated STE-induced changes in p53. The expression of antiapoptotic Bcl-2 gene decreased with STE treatment and the expression of Bcl-2 gene increased significantly following preincubation with GSPE. No significant change in the expression of transcription factor c-myc gene responsible for cell cycle growth was observed following incubation with STE and/or GSPE. Thus, c-myc may not be involved in STE-induced cytotoxicity towards NHOK cells. These results suggest that antioxidant protection of STE-induced cellular injury is associated with alterations in Bcl-2 and p53 expression.
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PMID:Protective effects of antioxidants against smokeless tobacco-induced oxidative stress and modulation of Bcl-2 and p53 genes in human oral keratinocytes. 1169 99

Disease development in diabetes-prone BB rats is modified by the type of diet fed after weaning. The aim of this investigation was to determine whether exposure during the first week of life to antigens from a known diabetes-promoting diet (NIH-07) could modify diabetes incidence and, if so, to what extent this occurs via alterations in systemic T-cell reactivity, gut cytokines, or islet infiltration. Diabetes-prone BB (BBdp) rats were hand-fed twice daily between age 4 and 7 days with vehicle, a hydrolyzed casein (HC)-based infant formula, Pregestimil (PG), PG + cereal-based NIH-07 diet, PG + lipopolysaccharides (LPS) or PG + LPS + silica. After weaning, they were fed either an NIH-07 diet or a semipurified HC (diabetes-retardant) diet until 150 days. In separate studies, 5-day-old BBdp rat pups were administered the aforementioned treatments, and expression of intestinal mRNA for gamma-interferon (IFN-gamma) or transforming growth factor-beta (TGF-beta) was quantified using reverse transcriptase-polymerase chain reaction. The effect of early oral treatment with NIH-07 or PG on systemic T-cell reactivity was evaluated using footpad swelling delayed-type hypersensitivity (DTH) and the popliteal lymph node assay. Oral exposure of neonates to a complex mixture of antigens from the diabetes-promoting diet delayed onset of diabetes (79 vs. 88 days) and prevented disease in approximately one-third of animals. A similar protective effect was seen for neonatal exposure to wheat gluten in animals subsequently weaned onto a semipurified wheat gluten diet. By contrast, LPS-treated neonates displayed more severe insulitis and developed diabetes at an increased rate, which was significantly suppressed by co-administration of silica particles. The protective effect of early exposure to diabetogenic diets was not associated with significant reduction of islet infiltration, and there was no impact on the DTH response to food antigens. However, whereas diabetes-resistant BBc rats developed systemic tolerance to NIH-07 antigens fed chronically, BBdp rats did not. The lack of effect of the early oral antigen regimen on the DTH reaction in the footpad, a classic Th1-mediated reaction, suggests little effect on systemic T-cell reactivity. However, local effects were observed in the small intestine. Oral exposure to diabetes-promoting food antigens or LPS downregulated the Th1 cytokine IFN-gamma and decreased the IFN-gamma/TGF-beta ratio. Thus, oral exposure to diabetes-promoting food antigens and immune modulators in neonates can modify diabetes expression in association with changes in local cytokine balance in the gut.
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PMID:Oral exposure to diabetes-promoting food or immunomodulators in neonates alters gut cytokines and diabetes. 1175 25

The third postnatal week of mouse development is characterized by dramatic changes of gene expression in the small intestine. Although these changes are often assumed to reflect regulation at the level of transcription, to date there have been no direct investigations of this. In the current study we have used trehalase as a marker of intestinal maturation. Highly sensitive reverse transcriptase-polymerase chain reaction methods were developed for semi-quantitative analysis of both initial and mature transcripts, i.e., hnRNA and mRNA. Jejunums collected during normal development (specifically from postnatal days 8-21) showed parallel increases in the levels of trehalase hnRNA and mRNA. Likewise, when precocious gut maturation was elicited by dexamethasone administration on days 8-10, both initial and mature trehalase transcripts were significantly increased, although with a relatively slow time course. We conclude that both normal and glucocorticoid-induced maturation of trehalase expression reflect transcriptional activation. However, the slow time course of the glucocorticoid effect suggests that trehalase may not be a primary response gene.
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PMID:Developmental expression of trehalase: role of transcriptional activation. 1199 99

The presence and distribution of pituitary adenylate cyclase activating peptide (PACAP) immunoreactivity were studied in the duck gastrointestinal tract using immunohistochemistry and radioimmunoassays. Expression and distribution of PACAP mRNA were also studied using reverse transcriptase polymerase chain reaction (RT-PCR) and hybridization techniques. In addition, a partial coding sequence (cds) of the duck growth hormone-releasing hormone (GRF)/PACAP gene was identified. The presence of both PACAP-38 and PACAP-27 was demonstrated, the former being the predominant form. PACAP immunoreactivity was found in neurons and fibers of the enteric nervous system (ENS), in endocrine cells and in the gut associated lymphoid tissue (GALT). Double immunostaining showed that PACAP is almost completely colocalized with vasoactive intestinal peptide (VIP) in the ENS. Moreover, PACAP was also found in nitric oxide synthase (NOS)-containing neurons and nerve fibers. Radioimmunoassay (RIA) performed on denervated gut showed that more than one-half of the duodenal PACAP is extrinsic in origin. RT-PCR, Northern blot analysis and in situ hybridization confirmed the immunohistochemical data. The findings of the present study suggest that, in birds, PACAP may have multiple roles in regulating gastrointestinal functions.
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PMID:Pituitary adenylate cyclase activating peptide (PACAP) immunoreactivity and mRNA expression in the duck gastrointestinal tract. 1210 28

While comparing gene expression in the pathogenic organism Entamoeba histolytica and the closely related but nonpathogenic species Entamoeba dispar, we discovered that the E. histolytica abundant polyadenylated transcript 2 (ehapt2) and corresponding genomic copies are absent in E. dispar. Although polyadenylated, ehapt2 does not contain any overt open reading frame. Southern blot and sequence analyses revealed that about 500 copies of ehapt2 genomic elements were present in each cell and that the copies were distributed throughout the ameba genome. The various ehapt2 elements are regularly located in the vicinity of protein-encoding genes, downstream of pyrimidine-rich sequence stretches (40 to 125 bp; CT content, 79.2 to 85.5%), and are flanked by duplicated target sites of variable length. Target site duplications were obviously generated during integration of ehapt2 into the E. histolytica genome as one copy of the flanking repeat and the complete ehapt2 element are specifically absent in orthologous E. dispar genomic sequences. ehapt2 shares 3' sequences with EhRLE, a recently identified non-long-terminal-repeat (non-LTR) retrotransposon-like element of E. histolytica, which contains a conceptual open reading frame for reverse transcriptase. Thus, ehapt2 has all of the properties of nonautonomous non-LTR retrotransposons. A comparison of various E. histolytica isolates suggested that transposition of ehapt2 takes place at a very low frequency as the genomic localization of ehapt2 elements was found to be well conserved. A mobile element such as ehapt2 could be a suitable mechanism to explain the infrequent and late transition of E. histolytica from a harmless gut commensal to an invasive pathogen.
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PMID:The abundant polyadenylated transcript 2 DNA sequence of the pathogenic protozoan parasite Entamoeba histolytica represents a nonautonomous non-long-terminal-repeat retrotransposon-like element which is absent in the closely related nonpathogenic species Entamoeba dispar. 1243 55

The cytokine secretion profile of T cells present in the gastric antrum of Helicobacter pylori-infected patients with peptic ulcer and in the gut of patients with Crohn's disease was investigated. A type 1 T helper (Th1)-dominated response was detected in the gastric antrum of Helicobacter pylori-infected subjects with peptic ulcer by both reverse transcriptase-PCR and immunohistochemistry. By using a T-cell cloning technique, it was shown that the majority of Th 1 cells were specific for Hp antigens. A Th1 predominance, which associated with high IL-12 expression, was also found, at both clonal and immunohistochemical level, in the gut of patients with Crohn's disease. These findings suggest that the Th1/Th2 paradigm may be useful to explain the inflammatory reactions involved in the pathogenesis of some gastrointestinal disorders.
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PMID:Immune mechanisms in the pathogenesis of inflammatory gastrointestinal disorders. 1450 88

The non-long-terminal-repeat (non-LTR) retrotransposons (also called long interspersed repetitive elements [LINEs]) are among the oldest retroelements. Here we describe the properties of such an element from a primitive protozoan parasite, Entamoeba histolytica, that infects the human gut. This 4.8-kb element, called EhLINE1, is present in about 140 copies dispersed throughout the genome. The element belongs to the R4 clade of non-LTR elements. It has a centrally located reverse transcriptase domain and a restriction enzyme-like endonuclease (EN) domain at the carboxy terminus. We have cloned and expressed a 794-bp fragment containing the EN domain in Escherichia coli. The purified protein could nick supercoiled pBluescript DNA to yield open circular and linear DNAs. The conserved PDX(12-14)D motif was required for activity. Genomic sequences flanking the sites of insertion of EhLINE1 and the putative partner short interspersed repetitive element (SINE), EhSINE1, were analyzed. Both elements resulted in short target site duplications (TSD) upon insertion. A common feature was the presence of a short T-rich stretch just upstream of the TSD in most insertion sites. By sequence analysis an empty target site in the E. histolytica genome, known to be occupied by EhSINE1, was identified. When a 176-bp fragment containing the empty site was used as a substrate for EN, it was prominently nicked on the bottom strand at the precise point of insertion of EhSINE1, showing that this SINE could use the LINE-encoded endonuclease for its insertion. The nick on the bottom strand was toward the right of the TSD, which is uncommon. The lack of strict target site-specificity of the restriction enzyme-like EN encoded by EhLINE1 is also exceptional. A model for retrotransposition of EhLINE1/SINE1 is presented.
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PMID:An Entamoeba histolytica LINE/SINE pair inserts at common target sites cleaved by the restriction enzyme-like LINE-encoded endonuclease. 1487 47


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