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)

BACKGROUND-Chronic heart failure (CHF) impairs the endothelium-dependent, flow-mediated dilation (FMD) of small arteries. However, whether chronic angiotensin-converting enzyme (ACE) inhibition affects the impairment of FMD in CHF is unknown. We investigated the effects of long-term ACE inhibition on the FMD of peripheral arteries in rats with CHF and the mechanism(s) involved. METHODS AND RESULTS-FMD was assessed in isolated, perfused gracilis muscle arteries from sham-operated, and untreated or ACE inhibitor-treated (perindopril 2 mg. kg(-1). day(-1) for 10 weeks) rats with CHF (coronary artery ligation). The role of nitric oxide (NO), prostaglandins, and free radicals was assessed by pretreating the vessels with the NO synthase inhibitor N(W)-nitro-L-arginine, the cyclooxygenase inhibitor diclofenac, or the free radical scavenger N-2-mercaptopropionyl-glycine (MPG). Endothelial NO synthase mRNA expression was determined by reverse transcriptase polymerase chain reaction. In animals with hemodynamic and echographic signs of CHF, FMD was converted into vasoconstriction, and this was prevented by ACE inhibition. FMD of arteries from sham-operated or ACE inhibitor-treated CHF rats was abolished by N(W)-nitro-L-arginine. In untreated CHF rats, FMD was increased by diclofenac and MPG. In contrast, in arteries from ACE inhibitor-treated rats, neither diclofenac nor MPG affected FMD. In parallel, ACE inhibition prevented the reduction of endothelial NO synthase mRNA by CHF. CONCLUSIONS-In CHF, ACE inhibition normalized NO-dependent dilatation and suppressed the production of vasoconstrictor prostanoid(s), resulting in improved FMD. The improvement of FMD might contribute to the beneficial effects of ACE inhibition during CHF.
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PMID:Improvement of endothelial function by chronic angiotensin-converting enzyme inhibition in heart failure : role of nitric oxide, prostanoids, oxidant stress, and bradykinin. 1089 1

Prolonged exposure of rodent beta-cells to combinations of cytokines induces the inducible form of nitric oxide synthase (iNOS) expression and Fas expression, nitric oxide (NO) production, and cell death. It also induces the expression of potential "defense" genes, such as manganese superoxide dismutase (MnSOD) and heat shock protein (hsp) 70. NO is a radical with multifaceted actions. Recent studies have shown that NO, in addition to having cytotoxic actions, may regulate gene transcription. It remains unclear whether NO mediates cytokine-induced gene expression and subsequent beta-cell death. Previous studies using NO synthase blockers yielded conflicting results, which may be due to nonspecific effects of these agents. In this study, we examined the effects of cytokines on gene expression, determined by reverse transcriptase-polymerase chain reaction (RT-PCR), and viability, determined by nuclear dyes, of pancreatic islets or fluorescence-activated cell sorter (FACS)-purified beta-cells isolated from iNOS knockout mice (iNOS-/-, background C57BL/6x129SvEv) or their respective controls (C57BL/6x129SvEv). The combination of cytokines used was interleukin-1beta (50 U/ml) plus gamma-interferon (1,000 U/ml) plus tumor necrosis factor-alpha (1,000 U/ml). The lack of cytokine-induced iNOS activity in the iNOS-/- islet cells was confirmed by RT-PCR and nitrite determination. Cytokines induced a >3-fold increase in Fas and MnSOD mRNA expression in wild-type (WT) and iNOS-/- islets. On the other hand, hsp 70 was induced in WT but not in iNOS-/- islets. Prolonged (6-9 days) exposure of WT islets to cytokines leads to an 80-90% decrease in islet cell viability, whereas viability decreased by only 10-30% in iNOS-/- islet cells. To determine the mode of cytokine-induced cell death, FACS-purified beta-cells were exposed to the same cytokines. After 9 days, the apoptosis index was similarly increased in WT (39 +/- 3%) and iNOS4-/- (33 +/- 4%) beta-cells. On the other hand, cytokines increased necrosis in WT (20 +/- 4%) but not in iNOS-/- (7 +/- 3%) beta-cells. From these data, we concluded that 1) NO is required for cytokine-induced hsp 70 mRNA expression but not for Fas and MnSOD expression, 2) cytokines induce both apoptosis and necrosis in mouse beta-cells, and 3) cytokine-induced apoptosis is mostly NO-independent, whereas necrosis requires NO formation.
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PMID:Cytokines induce apoptosis in beta-cells isolated from mice lacking the inducible isoform of nitric oxide synthase (iNOS-/-). 1090 67

Exposure of pancreatic islets to cytokines such as interleukin (IL)-1beta induces a variety of proinflammatory genes including type II nitric-oxide synthase (iNOS) which produces nitric oxide (NO). NO is thought to be a major cause of islet beta-cell dysfunction and apoptotic beta-cell death, which results in type I diabetes. Since protein kinase C (PKC) mediates some of the actions of cytokines in other cell types, our aim was to assess the role of PKC in IL-1beta-induced iNOS expression in pancreatic beta-cells. PKCdelta, but not PKCalpha, was specifically activated in the rat INS-1 beta-cell line by IL-1beta as assessed by membrane translocation. Moreover, iNOS expression and NO production were significantly attenuated by the PKCdelta specific inhibitor rottlerin and overexpression of a PKCdelta kinase-dead mutant protein. Conversely, overexpression of PKCdelta wild type protein significantly potentiated this response. These results were confirmed at the mRNA level by reverse transcriptase-polymerase chain reaction. However, a role at the level of transcriptional regulation appeared unlikely, since PKCdelta was not required for the activation of NF-kappaB, activating protein 1, and activating transcription factor 2 signaling pathways in response to IL-1beta. There was, however, a significant increase in iNOS mRNA stability mediated by PKCdelta wild type, while PKCdelta kinase-dead acted reciprocally, reducing iNOS mRNA stability. The results indicate that, in addition to transcriptional activation, mRNA stabilization is a key component of the mechanism by which IL-1beta stimulates iNOS expression in beta-cells and that PKCdelta plays an essential role in this process. PKCdelta activation may therefore have significant consequences with regard to cellular function and viability when beta-cells are exposed to IL-1beta and potentially other cytokines.
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PMID:Protein kinase Cdelta activation by interleukin-1beta stabilizes inducible nitric-oxide synthase mRNA in pancreatic beta-cells. 1108 60

We have characterized brain cytokine expression profiles in the Plasmodium coatneyi/rhesus (Macaque mulatta) malaria model. Eight rhesus monkeys were included in the study; four were infected with P. coatneyi, and four were used as uninfected controls. All inoculated animals became infected. Eleven days after parasite inoculation, the rhesus monkeys were killed and tissue samples from 4 regions of the brain (cortex and white matter of the cerebrum, cerebellum, and midbrain) were collected for quantitation of mRNA expression of cytokines, adhesion molecules, and inducible nitric oxide synthetase (iNOS) by reverse transcriptase-polymerase chain reaction (RT-PCR). The expression levels of tumor necrosis actor-alpha (TNF-alpha), gamma interferon (IFN-gamma), interleukin-1-beta (IL-1beta), intercellular adhesion molecule-1 (ICAM-1) and inducible nitric oxide synethetase (iNOS) were highest in the cerebellum of infected animals, correlating well with pathologic observations of sequestration of parasitized erythrocytes in this region of the brain. Infected animals also had higher TNF-alpha expression levels in the cortex and IL-1beta expression levels in the cortex, white matter, and midbrain. Thus, the expression of pro-inflammatory and T helper-1 (TH-1) cytokines, adhesion molecules, and iNOS appears to predominate in the cerebellum of infected rhesus monkeys.
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PMID:Expression of proinflammatory cytokines in four regions of the brain in Macaque mulatta (rhesus) monkeys infected with Plasmodium coatneyi. 1122 Jul 73

The mechanisms underlying the development of hypertension in obesity are not yet fully understood. We recently reported the development of hypertension in a rat model of diet-induced obesity. When Sprague-Dawley rats (n=60) are fed a moderately high fat diet (32 kcal% fat) for 10 to 16 weeks, approximately half of them develop obesity (obesity-prone [OP] group) and mild hypertension (158+/-3.4 mm Hg systolic pressure), whereas the other half (obesity-resistant [OR] group) maintains a body weight equivalent to that of a low fat control group and is normotensive (135.8+/-3.8 mm Hg). We examined the potential role of oxidative stress in the development of hypertension in this model. Lipid peroxides measured as thiobarbituric acid-reactive substances showed a significant increase in the LDL fraction of OP rats (2.8+/-0.32 nmol malondialdehyde/mg protein) compared with OR and control rats (0.9+/-0.3 nmol malondialdehyde/mg protein). Also, aortic and kidney thiobarbituric acid-reactive substances showed a significant (3- and 5- fold) increase in OP rats after 16 weeks of diet. In addition, superoxide generation by aortic rings, measured by lucigenin luminescence, showed a 2-fold increase in the OP group compared with both the OR and control groups. In addition, free isoprostane excretion and nitrotyrosine in the kidney showed an increase in OP rats only. The urine and plasma nitrate/nitrite measured by the LDH method showed a 1.8-fold decrease in OP rats compared with OR rats. However, endothelial NO synthase expression in the kidney cortex and medulla assessed by reverse transcriptase-polymerase chain reaction showed a strong increase in the OP rats versus OR and control rats (endothelial NO synthase/beta-actin ratio 1.3+/-0.04 in OP rats versus 0.44+/-0.02 in OR rats), suggesting a possible shift toward superoxide production by the enzyme. Collectively, the data show a decreased NO bioavailability in OP animals that is due in part to the increased oxidative stress.
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PMID:Oxidative stress in a rat model of obesity-induced hypertension. 1123 Mar 34

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.
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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

Meconium aspiration causes intensive inflammatory reactions in the lungs, and may lead to neonatal respiratory disorder. Infiltrated inflammatory cells, particularly macrophages, play an important role in such an inflammation. A rat alveolar macrophage cell line (ATCC8383) was exposed to meconium alone or in combination with dexamethasone, budesonide, or interferon-gamma. Nitric oxide (NO) accumulation in the supernatant of the cell culture was detected by Griess reaction, and mRNA of inducible NO synthase (iNOS) expression was detected by reverse transcriptase-PCR. Nuclear factor-kappa B was analyzed by electrophoretic mobility shift assay, and iNOS location and nuclear factor-kappa B transactivation were determined by immunostaining. Our results showed that meconium was capable of inducing production of NO and expression of iNOS in alveolar macrophages in a dose- (1-25 mg/mL, p < 0.05) and time- (4-48 h, p < 0.05) dependent manner. This capability of meconium could be further enhanced in the presence of interferon-gamma (100 IU/mL, p < 0.05). Budesonide (10(-4)-10(-10) M) or dexamethasone (10(-4)-10(-6) M) effectively inhibited the meconium-induced NO production (p < 0.05). Using the protein synthesis inhibitor cycloheximide, we demonstrated that meconium directly induced iNOS in macrophages. Furthermore, meconium also triggered nuclear factor-kappa B activation, a mechanism possibly responsible for the iNOS expression. Our findings suggest that meconium is a potent inflammatory stimulus, resulting in iNOS expression, leading to overproduction of NO from the macrophages, which may be of pathogenic importance in meconium aspiration syndrome. In vitro steroids down-regulated the iNOS expression, thus suggesting a potential to down-regulate NO-mediated inflammation in neonates with meconium aspiration syndrome.
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PMID:Meconium induces expression of inducible NO synthase and activation of NF-kappaB in rat alveolar macrophages. 1138 44

Microglia are important in the inflammatory response in Alzheimer's disease (AD). We showed previously that macrophage colony-stimulating factor receptor (M-CSFR), encoded by the c-fms protooncogene, is overexpressed on microglia surrounding amyloid beta (Abeta) deposits in the APP(V717F) mouse model for AD. The M-CSFR is also increased on microglia after experimental brain injury and in AD. To determine the relevance of these findings, we transiently expressed M-CSFR on murine BV-2 and human SV-A3 microglial cell lines using an SV40-promoted c-fms construct. M-CSFR overexpression resulted in microglial proliferation and increased expression of inducible nitric-oxide synthase, the proinflammatory cytokines interleukin-1alpha, macrophage inflammatory protein 1-alpha, and interleukin-6 and of macrophage colony-stimulating factor (M-CSF) itself. Antibody neutralization of M-CSF showed that the M-CSFR-induced proinflammatory response was dependent on M-CSF in the culture media. By using a co-culture of c-fms-transfected murine microglia and rat organotypic hippocampal slices and a species-specific real time reverse transcriptase-polymerase chain reaction assay and enzyme-linked immunosorbent assay, we showed that M-CSFR overexpression on exogenous microglia induced expression of interleukin-1alpha by the organotypic culture. These results show that increased M-CSFR expression induces microglial proliferation, cytokine expression, and a paracrine inflammatory response, suggesting that in APP(V717F) mice increased M-CSFR on microglia could be an important factor in Abeta-induced inflammatory response.
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PMID:Overexpression of macrophage colony-stimulating factor receptor on microglial cells induces an inflammatory response. 1138 43

The autoimmune diabetic NOD mouse serves as a model for human type 1 diabetes. Disease development is due to islet beta cell destruction in the context of immune cell infiltration of islets and inflammatory changes throughout the pancreas. In the present study we tried to identify immune reactivity patterns in the pancreas associated with diabetes resistance in NOD-related mouse strains. The pancreata of diabetes-prone female NOD/LtJ, NOD/Bom and of genetically related but diabetes-resistant strains; NOR, NON, NON.NOD-H2g7, NOD.NON-H-2nbl were obtained at the age of 70 days for semiquantitative analysis of insulitis and of mRNA expression by reverse transcriptase PCR. In addition, the response to a single dose of cyclophosphamide for synchronizing and accelerating the progression of insulitis was determined. The progression of insulitis and immune gene expression in response to cyclophosphamide revealed characteristic differences between the six strains. NOD/LtJ and NOD/Bom mice were found significantly to upregulate pancreatic IL-12p40 and IL-18 expression after cyclophosphamide treatment, followed by an increase in IFN-gamma mRNA levels. In contrast, the two MHC-haplotype H-2nbl expressing strains either up-regulated neither IL-12/IL-18 nor IFN-gamma gene expression. The two strains sharing MHC haplotype H-2g7 expression with NOD did respond to cyclophosphamide with IL-12p40/IL-18 gene expression. However, NON.NOD-H-2g7 mice failed to progress to IFN-gamma gene expression. NOR mice progressed to IFN-gamma expression but exhibited sustained IL-4 gene expression. Only severe intra-insulitis was associated with the expression of inducible NO synthase. The comparison of diabetes-prone and diabetes-resistant strains revealed three checkpoints of immune regulation in the pancreas. The earliest checkpoint is the induction of an IL-12p40/IL-18 response in innate immune or antigen-presenting cells. The next level of control is at the induction of IFN-gamma gene expression, and a third checkpoint is the maintenance or loss of antagonistic Th2 type reactions.
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PMID:Disease resistant, NOD-related strains reveal checkpoints of immunoregulation in the pancreas. 1140 10

The production of nitric oxide (NO) within the middle ear has not previously been characterized. The presence of NO synthase (NOS) transcripts was demonstrated using RNA amplification by reverse transcriptase-polymerase chain reaction in rat middle ear mucosa and in rat primary cultured middle ear epithelial cells. The expression of NOS was indirectly assessed by nitrite measurement in the supernatant of primary cultured cells. The effect of NO on ion transport was investigated in a previously described middle ear epithelial cell line using the short-circuit current (Isc) technique. NO per se had no effect on Isc. However, previous work has shown that sodium transport is stimulated by reactive oxygen species (ROS). NO blunted this stimulation, an inhibition probably related to the toxicity of peroxynitrite, ONOO-, a highly reactive compound. These results suggest that NO is produced by middle ear epithelial cells and that, in the presence of ROS, NO may be responsible for an inhibition of ion transport viaperoxynitrite formation.
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PMID:Production of nitric oxide by the middle ear epithelium and subsequent inhibition of sodium transport. 1142 3


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