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

---

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

Introducing recombinant genes into donor hearts may offer a therapeutic intervention that could potentially attenuate the complications of heart transplantation, including rejection, infection and accelerated atherosclerosis. In the cardiovascular system, reduced bioactivity of endothelial nitric oxide is a feature of atherosclerosis and vascular injury. Nitric oxide is an arterial vasodilator that also inhibits proliferation of vascular smooth muscle cells and platelet aggregation. Experiments were designed to determine the distribution of adenoviral-mediated transfer of recombinant endothelial nitric oxide synthase gene (eNOS) and the effect of recombinant gene expression on the function of transplanted hearts. Adenoviral vectors for (a) bovine eNOS (AdeNOS) or (b) beta-galactosidase (AdLacZ; control) were infused into two groups (n = 12, per group) of explanted rat hearts. The transduced hearts were then implanted heterotopically into the abdomen of syngeneic recipient rats. After four days, the hearts were excised and examined for distribution and function of the recombinant genes. Polymerase chain reaction (PCR) verified the presence of the recombinant eNOS gene in eNOS-transduced but not in beta-galactosidase-transduced hearts; reverse transcriptase-PCR identified mRNA for eNOS in AdeNOS-transduced hearts. NOS activity (conversion of tritiated L-arginine to citrulline) was greater in homogenates of AdeNOS-compared to AdLacZ-transduced hearts. Positive immunoreactivity for eNOS was present in cardiomyocytes predominantly in eNOS-transduced hearts. Myocardial contractility and coronary blood flow, as determined using a Langendorff preparation, were not different between hearts transduced with AdeNOS or AdLacZ. These results suggest that, up to four days post transplantation, adenoviral-mediated transfer of eNOS into transplanted hearts is possible. However, expression of the recombinant protein did not result in measurable changes in myocardial contractility or coronary perfusion.
...
PMID:Distribution and function of recombinant endothelial nitric oxide synthase in transplanted hearts. 1053 12

In order to elucidate further the role of nitric oxide (NO) as an endogenous antiangiogenic mediator, mRNA expression of inducible nitric oxide synthase (iNOS), enzyme activity and production of NO were determined in the chick chorioallantoic membrane (CAM), an in vivo model of angiogenesis. In this model, maximum angiogenesis is reached between days 9 - 12 of chick embryo development. After that period, vascular density remains constant. Inducible NO synthase (iNOS) mRNA expression, determined by reverse transcriptase polymerase chain reaction (RT - PCR), increased from the 8th day reaching a maximum (70% increase) at days 10 - 11. NO synthase activity, determined as citrulline formation in the presence of calcium, also increased from day 8 reaching a maximum around day 10 (100% increase). Similar results were obtained in the absence of calcium suggesting that the NOS determined was the inducible form. Nitric oxide production, determined as nitrites, increased from day 8 reaching a maximum around day 10 (64% increase) and remaining stable at day 13. Finally, the bacterial lipopolysaccharide LPS (which activates transcriptionally iNOS), inhibited dose dependently angiogenesis in the CAM. These results in connection with previous findings from this laboratory, showing that NO inhibits angiogenesis in the CAM, suggest that increases in iNOS expression, enzyme activity and NO production closely parallel the progression of angiogenesis in the CAM, thus providing an endogenous brake to control this process. British Journal of Pharmacology (2000) 129, 207 - 213
...
PMID:Nitric oxide synthase expression, enzyme activity and NO production during angiogenesis in the chick chorioallantoic membrane. 1069 22

Expression of the inducible isoform of nitric oxide synthase (iNOS) is stimulated by cytokines in human epithelial cells. This work indicates that incubation of human umbilical cord endothelial cells with combinations of interleukin-1beta, tumor necrosis factor alpha, and interferon-gamma stimulated the synthesis of iNOS mRNA, as detected by reverse transcriptase-polymerase chain reaction. It is important to note that 50, 100, and 200 microM hydrogen peroxide was able to stimulate iNOS directly. Furthermore, 100 microM H2O2 enhanced synthesis of the oxidation products, nitrite (NO2-) and nitrate (NO3-) at 12 and 36 h. iNOS protein, detected by Western blot analysis, as well as L-citrulline levels, were also increased. When endothelial cell monolayers were incubated for 1 h with 100 microM H2O2 and subsequently with cytokines, iNOS mRNA was further augmented. Under the same conditions, we regularly observed an inhibition (25%) of intercellular adhesion molecule-1 (ICAM-1/CD54) expression. The latter was reversed when the NOS inhibitor N(G)-monomethyl-L-arginine was added, as shown by flow cytometry. These data suggest a specific effect of endogenous hydroperoxides on the biosynthesis and processing of the human endothelial iNOS isoform. We propose that H2O2 induces a temporary NO-dependent modulation of adhesion molecule expression to limit the tissue destruction that accompanies the vascular recruitment of leukocytes.
...
PMID:Regulation of ICAM-1/CD54 expression on human endothelial cells by hydrogen peroxide involves inducible NO synthase. 1073 92

During hemorrhagic shock there is a massive overproduction of nitric oxide (NO). In such conditions, the intravenous (i.v.) injection of melanocortin peptides in nanomolar amounts produces a long-lasting restoration of cardiovascular and respiratory functions associated with the normalization of NO blood levels. To clarify the mechanism of such melanocortin-induced inhibition of NO overproduction, the influence of the adrenocorticotropin fragment 1-24 [ACTH-(1-24)] on the NO synthesizing activity of rat macrophages was studied in vitro. Nitrite production, an indicator of NO synthesis, was measured in the supernatant of rat macrophages whose inducible NO synthase (NOS II, iNOS) had been stimulated by the addition of S. enteritidis lipopolysaccharide (LPS, 50 microg/ml). ACTH-(1-24) (25, 50 and 100 nM) inhibited nitrite production when incubated together with LPS, but had no effect when applied 6 h after LPS. Further, the effect of ACTH-(1-24) on the expression of iNOS mRNA in rat macrophages activated with LPS was studied by means of a reverse transcriptase-polymerase chain reaction assay. ACTH-(1-24) (25, 50 and 100 nM), applied together with LPS, dose-dependently suppressed iNOS gene activation. The present data suggest that the melanocortin-induced normalization of NO blood levels during hemorrhagic shock is due, at least in part, to a direct inhibition of iNOS induction, at the level of mRNA transcription.
...
PMID:Adrenocorticotropin inhibits nitric oxide synthase II mRNA expression in rat macrophages. 1085 45

A synthetic peptide consisting of amino acid residues 106-126 of the human prion protein (PrP-(106--126)) has been previously demonstrated to be neurotoxic and to induce microglial activation. The present study investigated the expression of the inducible form of the nitric-oxide synthase (NOS-II) in human microglial cells treated with PrP-(106--126). Using reverse transcriptase-polymerase chain reaction, we found that PrP-(106--126) induces NOS-II gene expression after 24 h of treatment and that this effect is accompanied by a peak of nuclear factor kappa B (NF-kappa B) binding at 30 min as evaluated by electrophoretic mobility shift assay. Since our previous data demonstrated tumor necrosis factor-alpha (TNF-alpha) to be a potent inducer of NOS-II in these cells, we analyzed the expression of this cytokine in PrP-(106--126)-treated microglia. PrP-(106--126) caused the release of TNF-alpha as detected by enzyme-linked immunosorbent assay, and a blocking antibody, anti-TNF-alpha, abolished NOS-II induction elicited by this peptide. Moreover, PrP-(106-126) activates p38 mitogen-activated protein kinase, and the inhibition of this pathway determines the ablation of NF-kappa B binding induced by this fragment peptide.
...
PMID:The stimulation of inducible nitric-oxide synthase by the prion protein fragment 106--126 in human microglia is tumor necrosis factor-alpha-dependent and involves p38 mitogen-activated protein kinase. 1131 2

Transgenic plants of Arabidopsis bearing the spinach (Spinacia oleracea) nitrite reductase (NiR, EC 1.7.7.1) gene that catalyzes the six-electron reduction of nitrite to ammonium in the second step of the nitrate assimilation pathway were produced by use of the cauliflower mosaic virus 35S promoter and nopaline synthase terminator. Integration of the gene was confirmed by a genomic polymerase chain reaction (PCR) and Southern-blot analysis; its expression by a reverse transcriptase-PCR and two-dimensional polyacrylamide gel electrophoresis western-blot analysis; total (spinach + Arabidopsis) NiR mRNA content by a competitive reverse transcriptase-PCR; localization of NiR activity (NiRA) in the chloroplast by fractionation analysis; and NO(2) assimilation by analysis of the reduced nitrogen derived from NO(2) (NO(2)-RN). Twelve independent transgenic plant lines were characterized in depth. Three positive correlations were found for NiR gene expression; between the total NiR mRNA and total NiR protein contents (r = 0.74), between the total NiR protein and NiRA (r = 0.71), and between NiRA and NO(2)-RN (r = 0.65). Of these twelve lines, four had significantly higher NiRA than the wild-type control (P < 0.01), and three had significantly higher NO(2)-RN (P < 0.01). Each of the latter three had one to two copies of spinach NiR cDNA per haploid genome. The NiR flux control coefficient for NO(2) assimilation was estimated to be about 0.4. A similar value was obtained for an NiR antisense tobacco (Nicotiana tabacum cv Xanthi XHFD8). The flux control coefficients of nitrate reductase and glutamine synthetase were much smaller than this value. Together, these findings indicate that NiR is a controlling enzyme in NO(2) assimilation by plants.
...
PMID:Nitrite reductase gene enrichment improves assimilation of NO(2) in Arabidopsis. 1140 1

Previously we have shown that calcitonin gene-related peptide (CGRP), a neuropeptide increases lipopolysaccharide- (LPS) induced nitric oxide (NO) production in mouse peritoneal macrophages by using the Griess method. In this study we further examined whether CGRP could modulate inducible NO synthase (iNOS) protein and mRNA expression from mouse peritoneal macrophages. Macrophages were obtained from the peritoneal exude of male Balb/c mouse. The cells were plated on culture dishes at a density of 5 x 10(5) cells per well and were allowed to adhere for 2 h. After incubation for 24 h, the macrophages were cultured with 0.01 to 1 microg/mL LPS with or without CGRP (1-1,000 nM) for 24 h. The results showed that CGRP markedly enhanced 0.5 microg/mL LPS-induced NO release as compared with that of lower doses of LPS, such as 0.01 and 0.1 microg/mL LPS. NO was increased from 19.8 +/- 2.6 to the highest level of 31.5 +/- 4.2 microM in 5 x 10(5) cells by 10 nM CGRP in 0.5 microg/mL LPS-stimulated macrophages. The cGMP level in macrophages was augmented when CGRP was added with LPS. However, when using higher dose (1.0 microg/mL) of LPS to stimulate the macrophages, CGRP had no effect at all on NO release. CGRP had no direct effect on NO and cGMP production. CGRP increased the expression of inducible NOS protein in LPS-stimulated macrophages shown by immunocytochemistry method. The activity of iNOS was also enhanced by CGRP as compared with LPS-stimulation alone by detecting the 3H-L-citruline formation from 3H-L-arginine. We found that CGRP also increased the LPS-induced iNOS mRNA levels by using reverse transcriptase-PCR method. These data suggest that CGRP enhances LPS-induced NO release, iNOS activity, and iNOS mRNA in mouse peritoneal macrophages.
...
PMID:Calcitonin gene-related peptide-enhanced nitric oxide release and inducible NOS activity and mRNA expression in LPS-stimulated mouse peritoneal macrophages. 1144 18

Chronic exercise upregulates endothelial nitric oxide synthase (eNOS) gene expression. Whether the expression of inducible nitric oxide synthase (iNOS) is affected by exercise is unknown. We therefore investigated the effects of chronic exercise on iNOS and eNOS expression in isolated rat aortic endothelial and smooth muscle cells separately. Five-week-old male Wistar rats were randomly divided into control and exercise groups. After 10 weeks of running training, animals were sacrificed under ether anesthesia. The standard curve quantitative competitive reverse transcriptase-polymerase chain reaction method was used to quantify NOS mRNA expression in isolated endothelial/smooth muscle cells. To evaluate the functional role of iNOS, we examined phenylephrine-induced vascular responses with or without pretreatment with aminoguanidine. We found that (1) expression of iNOS and eNOS mRNA in endothelial cells was increased by chronic exercise and (2) chronic exercise blunted phenylephrine-induced vascular responses, probably by increasing NO release via iNOS. Our results show that chronic exercise increases both iNOS and eNOS gene expression in endothelium. These alterations may be partially responsible for the change in vascular response after exercise.
...
PMID:Chronic exercise increases both inducible and endothelial nitric oxide synthase gene expression in endothelial cells of rat aorta. 1191 82

N-methyl-D-aspartate receptor (NMDA-R) is an amino acid receptor and membrane calcium channel. NMDA-R is activated by binding of coagonists, L-glutamine and L-glycine. In the brain, calcium entry via NMDA-R activates type I nitric oxide synthase (NOS I). The kidney also contains NOS I and vasodilates in response to L-glycine. In this study, NMDA-R mRNA was demonstrated in rat kidney cortex by reverse transcriptase-PCR and cDNA sequencing. NMDA-R protein was demonstrated in kidney cortex by immunoblotting. To study the functional role of renal NMDA-R, renal hemodynamic effects of NMDA-R inhibition were assessed in rats using a blocker of the NMDA calcium channel (75 mg/kg MK-801 intraperitoneally) or an inhibitor of glycine binding to NMDA-R (30 mg/kg 5,7-dichlorokynurenic acid intraperitoneally). Renal blood flow was measured by perivascular pulse Doppler. GFR was measured by 3H-inulin clearance. Measurements were made before and during glycine infusion. Both NMDA-R antagonists caused renal vasoconstriction and attenuated the renal vasodilatory response to glycine infusion. These effects were not mediated by the renal nerves. The glycine response was not inhibited by aortic snare used to mimic the effects of NMDA-R inhibitors on basal renal blood flow. NMDA-R are expressed in kidney cortex, where they exert a tonic vasodilatory influence and may account for the vasodilatory response to glycine infusion.
...
PMID:Vasodilatory N-methyl-D-aspartate receptors are constitutively expressed in rat kidney. 1196 Oct 27

Melatonin, a major hormone of pineal gland, was recently shown to attenuate acute gastric lesions induced by strong irritants because of the scavenging of free radicals but its role in ulcer healing has been little investigated. In this study we compared the effects of intragastric (i.g.) administration of melatonin and its precursor, L-tryptophan, with or without concurrent treatment with luzindole, a selective antagonist of melatonin MT2 receptors, on healing of chronic gastric ulcers induced by serosal application of acetic acid (ulcer area 28 mm2). The involvement of endogenous prostaglandins (PG), nitric oxide (NO) and sensory nerves in ulcer healing action of melatonin and L-tryptophan was studied in rats treated with indomethacin and NG-nitro-L-arginine (L-NNA) to suppress, respectively, cyclo-oxygenases (COX) and NO synthases or in those with functionally deactivated sensory nerves with capsaicin. The influence of melatonin on gastric secretion during ulcer healing was tested in separate group of rats with gastric ulcer equipped with gastric fistulas (GF). At day 8 and 15 upon the ulcer induction, the area of gastric ulcers was measured by planimetry, the mucosal blood flow (GBF) was determined by H2-gas clearance technique and gastric luminal NO2-/NO3- levels was assessed by Griess reaction. Plasma melatonin and gastrin levels were measured by specific radioimmunoassay (RIA). Biopsy mucosal samples were taken for expression of constitutive NO-synthase (cNOS) and inducible NOS (iNOS) by reverse transcriptase-polymerase chain reaction (RT-PCR). Melatonin (2.5-20 mg/kg-d i.g.) and L-tryptophan (25-100 mg/kg-d i.g.) dose-dependently accelerated ulcer healing, the dose inhibiting by 50% (ED50) of ulcer area being 10 and 115 mg/kg, respectively. This inhibitory effect of melatonin (10 mg/kg-d i.g.) and L-tryptophan (100 mg/kg-d i.g.) on ulcer healing was accompanied by a significant rise in the GBF at ulcer margin and an increase of plasma melatonin. luminal NO2-/NO3- and plasma gastrin levels. Gastric acid and pepsin outputs were significantly inhibited during the ulcer healing in melatonin-treated gastric mucosa as compared with those in vehicle-treated animals. Luzindole abolished completely the healing effects of melatonin and L-tryptophan and attenuated significantly the rise in plasma gastrin evoked by the hormone and its precursor. Indomethacin (5 mg/kg-d i.p). that blocked PG biosynthesis by 90% or L-NAME (20 mg/kg i.v), inhibitor of NOS. that suppressed luminal NO release, attenuated significantly melatonin and L-tryptophan-induced acceleration of ulcer healing and accompanying rise in GBF at ulcer margin and luminal NO release. The melatonin-induced acceleration of ulcer healing, hyperemia at ulcer margin and increase in the release of NO were enhanced when L-arginine but not D-arginine was added to L-NAME. The ulcer healing and the GBF effects of melatonin and L-tryptophan were significantly impaired in rats with capsaicin-induced denervation of sensory nerves and both, ulcer healing and the hyperemia at ulcer margin were restored in these rats by addition of exogenous CGRP to melatonin and L-tryptophan. Expression of cNOS mRNA was detected by RT-PCR in the intact gastric mucosa as well as at the edge of gastric ulcers treated with both, vehicle and melatonin, while iNOS mRNA that was undetectable in the intact gastric mucosa, appeared during ulcer healing and especially this was strongly up-regulated in the melatonin-treated gastric mucosa. We conclude that (1) exogenous melatonin and that derived from its precursor, L-tryptophan, accelerate ulcer healing probably via interaction with MT2 receptors; (2) this ulcer healing action is caused by an enhancement by melatonin of the microcirculation at the ulcer margin possibly mediated by COX-derived PG and NO because of overexpression of iNOS and (3) gastrin, which exhibits trophic activity in the gastric mucosa and calcitonin gene related peptide (CGRP), released from sensory nerves, may also contribute to the ulcer healing action of melatonin.
...
PMID:Role of prostaglandins, nitric oxide, sensory nerves and gastrin in acceleration of ulcer healing by melatonin and its precursor, L-tryptophan. 1207 98


<< Previous 1 2 3 4 5 Next >>

---