Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adenosine inhibits growth of cardiac fibroblasts; however, the adenosine receptor subtype that mediates this antimitogenic effect remains undefined. Therefore, the goals of this study were to determine which adenosine receptor subtype mediates the antimitogenic effects of adenosine and to investigate the signal transduction mechanisms involved. In rat left ventricular cardiac fibroblasts, PDGF-BB (25 ng/mL) stimulated DNA synthesis ((3)H-thymidine incorporation), cellular proliferation (cell number), collagen synthesis ((3)H-proline incorporation), and MAP kinase activity. The adenosine receptor agonists 2-chloroadenosine and 5'-N-methylcarboxamidoadenosine, but not N(6)-cyclopentyladenosine, 4-aminobenzyl-5'-N-methylcarboxamidoadenosine, or CGS21680, inhibited the growth effects of PDGF-BB, an agonist profile consistent with an A(2B) receptor-mediated effect. The adenosine receptor antagonists KF17837 and 1,3-dipropyl-8-p-sulfophenylxanthine, but not 8-cyclopentyl-1,3-dipropylxanthine, blocked the growth-inhibitory effects of 2-chloroadenosine and 5'-N-methylcarboxamidoadenosine, an antagonist profile consistent with an A(2) receptor-mediated effect. Antisense, but not sense or scrambled, oligonucleotides to the A(2B) receptor stimulated basal and PDGF-induced DNA synthesis, cell proliferation, and collagen synthesis. Moreover, the growth-inhibitory effects of 2-chloroadenosine, 5'-N-methylcarboxamidoadenosine, and erythro-9-(2-hydroxy-3-nonyl) adenine plus iodotubericidin (inhibitors of adenosine deaminase and adenosine kinase, respectively) were abolished by antisense, but not scrambled or sense, oligonucleotides to the A(2B) receptor. Our findings strongly support the hypothesis that adenosine causes inhibition of CF growth by activating A(2B) receptors coupled to inhibition of MAP kinase activity. Thus, A(2B) receptors may play a critical role in regulating cardiac remodeling associated with CF proliferation. Pharmacologic or molecular biological activation of A(2B) receptors may prevent cardiac remodeling associated with hypertension, myocardial infarction, and myocardial reperfusion injury after ischemia.
 ...
PMID:A(2b) receptors mediate the antimitogenic effects of adenosine in cardiac fibroblasts. 1123 Mar 62

Nuclear factor kappaB (NF-kappaB) is thought to play an important role in the expression of genes expressed in response to ischemia/reperfusion (I/R) injury. In this report, the activation of NF-kappaB in rat skeletal muscle during reperfusion following a 4-h ischemic period was studied. NF-kappaB activation displayed a biphasic pattern, showing peak activities from 30 min to 3 h postperfusion and 6 h to 16 h postperfusion, with a decline to baseline binding activity levels between 3 h and 6 h. Inhibition of NF-kappaB activation was investigated using proline dithiocarbamate (Pro-DTC). NF-kappaB binding activity during reperfusion was significantly reduced by intravenous administration of Pro-DTC. Additionally, Pro-DTC resulted in decreased muscle edema and neutrophil activity, with an increased percentage of muscle survival compared with vehicle controls. These results demonstrate that NF-kappaB is activated during reperfusion in a biphasic manner and that the regulation of the initial phase of NF-kappaB activation affords physiological protection against a severe ischemic stress. Selective inhibition of NF-kappaB during early reperfusion may therefore be a therapeutic intervention for I/R injury.
 ...
PMID:Inhibition of the initial wave of NF-kappaB activity in rat muscle reduces ischemia/reperfusion injury. 1126 26

To understand the mechanisms underlying ischemia-reperfusion-induced renal proximal tubule damage, we analyzed the expression of the Na+-dependent phosphate (Na+/Pi) cotransporter NaPi-2 in brush border membranes (BBM) isolated from rats which had been subjected to 30 min renal ischemia and 60 min reperfusion. Na+/Pi cotransport activities of the BBM vesicles were also determined. Ischemia caused a significant decrease (about 40%, P < 0.05) in all forms of NaPi-2 in the BBM, despite a significant increase (31+/-3%, P < 0.05) in the Na+/Pi cotransport activity. After reperfusion, both NaPi-2 expression and Na+/Pi cotransport activity returned to control levels. In contrast with Na+/Pi cotransport, ischemia significantly decreased Na+-dependent glucose cotransport but did not affect Na+-dependent proline cotransport. Reperfusion caused further decreases in both Na+/glucose (by 60%) and Na+/proline (by 33%) cotransport. Levels of NaPi-2 were more reduced in the BBM than in cortex homogenates, suggesting a relocalization of NaPi-2 as a result of ischemia. After reperfusion, NaPi-2 levels returned to control values in both BBM and homogenates. These data indicate that the NaPi-2 protein and BBM Na+/Pi cotransport activity respond uniquely to reversible renal ischemia and reperfusion, and thus may play an important role in maintaining and restoring the structure and function of the proximal tubule.
 ...
PMID:Effect of ischemia-reperfusion on the renal brush-border membrane sodium-dependent phosphate cotransporter NaPi-2. 1129 96

Local ischemia may play an important role in the development of tendon degeneration as well as entrapment neuropathies. In order to investigate the cellular effects of hypoxia on tendon and synovial tissue from the carpal canal, dose response effects of oxygen on cell proliferation and synthesis of matrix components were examined in segments of synovial and flexor digitorum profundus tendon from the carpal tunnel of rabbits during short term culture. Explants were incubated in airtight containers flushed with either 0%, 1%, 3%, 20% O2 plus 2% CO2 and N2 to balance and labeled with either 3H-thymidine or 3H-proline and 35S-sulfate. Cell proliferation was significantly inhibited by hypoxia in synovium but not in tendon (P = 0.03). In parallel, the synthesis of non-collagenous proteins was significantly reduced in synovium but not in tendon (P = 0.006). In both tissues hypoxia significantly inhibited collagen synthesis. On the other hand, hypoxia had no significant effect on the synthesis of new proteoglycans as determined by 35S-sulfate incorporation. Hypoxia can inhibit cell proliferation and alter synthesis of matrix components in synovial tissue, but may only have minor effects on non-collagen protein synthesis in tendon explants from the carpal canal of rabbit forepaws.
 ...
PMID:The effects of reduced oxygen tension on cell proliferation and matrix synthesis in synovium and tendon explants from the rabbit carpal tunnel: an experimental study in vitro. 1133 11

Pro-rich antimicrobial peptides are a group of linear peptides of innate immunity isolated from mammals and invertebrates, and characterised by a high content of proline residues (up to 50%). Members of this group are predominantly active against Gram-negative bacterial species which they kill by a non-lytic mechanism, at variance with the majority of the known antimicrobial peptides. Evidence is accumulating that the Pro-rich peptides enter the cells without membrane lysis and, once in the cytoplasm, bind to, and inhibit the activity of specific molecular targets essential to bacterial growth, thereby causing cell death. This mode of action makes these peptides suitable for drug development efforts. In addition to antibacterial action, PR-39, one of the better characterised Pro-rich peptides from mammals, exerts other potentially exploitable biological activities, such as induction of syndecan expression in mesenchymal cells and inhibition of the NADPH oxidase activity of neutrophils, suggesting a role of this peptide in wound repair and inflammation. PR-39 also exerts a protective effect in various animal models of ischemia-reperfusion injury, preventing the post-ischemic oxidant production, and is a potent inducer of angiogenesis both in vitro and in vivo. Although the physiological relevance of all these effects has not yet been established, the above observations underscore the therapeutic potential of this peptide in a number of complex processes such as inflammation, wound repair, ischemia-reperfusion injury, and angiogenesis.
 ...
PMID:Pro-rich antimicrobial peptides from animals: structure, biological functions and mechanism of action. 1194 70

Activator protein 1 (AP-1) is thought to play an important role in the expression of genes expressed in response to ischemia-reperfusion injury. In this report, the activation of AP-1 in rat skeletal muscle during reperfusion after a 4-hour ischemic period was studied. AP-1 activation displayed a biphasic pattern, showing peak activities at 1 hour after perfusion and from 4 hours to 12 hours after perfusion. Inhibition of AP-1 activation was investigated using a potent nuclear factor kappa B inhibitor, proline dithiocarbamate (Pro-DTC). AP-1 binding activity at 1 hour of reperfusion was significantly reduced (29.0 +/- 10.1% SEM; p < 0.05) after intravenous administration of Pro-DTC (n = 7 animals in each group). Further elucidation of the role of AP-1 is warranted in hopes of developing strategies to reduce the deleterious effects of ischemia-reperfusion injury.
 ...
PMID:Activation time course of activator protein-1 and effect of proline dithiocarbamate during ischemia-reperfusion in rat skeletal muscle. 1246 50

The paper describes pharmacological properties of the new nootropic drug noopept created using an original approach based on the imitation of a nonpeptide nootrope structure by means of the short-peptide design. In particular, the structure of pyracetam was designed using dipeptide nootropes. Experimental investigations of noopept (N-phenylacetyl-L-polyglycine ethyl ester) showed that the new drug exceeds pyracetam both with respect to the effective dose level (1000 times lower for noopept than for pyracetam) and in the spectrum of mnemotropic activity. In contrast to pyracetam facilitating only the early stages of the memory process, noopept positively influences the memory consolidation and retrieval steps as well. The new drug produces an additional selective anxiolytic action. The pronounced neuroprotective effect of noopept was demonstrated both in vivo (in cases of various forms of brain ischemia) and in vitro (on various neuronal models). The drug action is based on the antioxidant effect, the antiinflammatory action, and the ability to inhibit the neurotoxicity of excess calcium and glutamate, and to improve the blood rheology. It was established for the first time that the activity of noopept is retained both upon parenteral introduction and upon peroral administration, which is a principal advantage of this proline-containing dipeptide over other, more complex peptides. This property provided a basis for the development of a medicinal form of noopept for peroral usage. At present, noopept tablets (noopept 5 and 10 mg) are under clinical assessment as a means of treating cognitive deficiency of cerebrovascular and post-traumatic origin.
 ...
PMID:[The original novel nootropic and neuroprotective agent noopept]. 1259 21

Glycine-proline-glutamate (GPE) is the N-terminal tripeptide of insulin-like growth factor-1 and has been shown to be neuroprotective following ischemia-induced brain injury. The pharmacokinetics of GPE were studied in adult rats since GPE is a candidate for use in neuroprotection therapies. To measure plasma concentrations of GPE a novel radioimmunoassay was developed whereby GPE was initially derivatized with Bolton and Hunter reagent before use in a standard homologous assay against the Bolton and Hunter iodinated form. The derivatized GPE radioimmunoassay showed a 83% recovery of unlabeled GPE and complete parallel displacement with rat plasma. The simplicity and speed of the assay described here indicate an exciting new use for a previously described technology. The pharmacokinetic studies were conducted in adult rats using a single bolus intravenous injection of GPE at 30 or 100 mg/kg and showed that GPE was rapidly cleared from the circulation. In addition, evidence of the route of the metabolic degradation of GPE is presented. The findings presented here are the first description of the pharmacokinetics of GPE and suggest that, because of its very short half-life in plasma, continuous intravenous infusion of GPE may be the preferred route of administration for use in future neuroprotection therapies.
 ...
PMID:Pharmacokinetics of glycine-proline-glutamate, the N-terminal tripeptide of insulin-like growth factor-1, in rats. 1465 20

Many molecular and physiological responses to hypoxia in mammals are controlled by the transcription factors Hypoxia-Inducible Factor-1alpha (HIF-1alpha) and HIF-2alpha. Their ability to promote the transcription of hypoxia-inducible genes is mediated by protein stability and regulation of a C-terminal transactivation domain. Oxygen-dependent hydroxylation of conserved proline and asparagine residues in HIF-alpha are required for targeting HIF-alpha to proteasomes for destruction, and for inhibiting its capacity for CBP/p300-dependent transactivation, respectively. In hypoxia, the O2 required for prolyl and asparaginyl hydroxylation is limiting, and HIF-alpha is thus stabilized and competent for transcription. Because these proteins participate in angiogenesis, glycolysis, programmed cell death, cancer, and ischemia, HIF-alpha and its mediators are attractive therapeutic targets.
 ...
PMID:Regulation of gene expression by the hypoxia-inducible factors. 1499 94

We have previously described a disulfide-linked cyclic nonapeptide (inhibitory peptide-01, IP01), with the sequence CLLRMRSIC, which binds to intercellular adhesion molecule-1 (ICAM-1), and blocks binding to its counter-structure, the integrin alphaLbeta2 (leukocyte functional antigen-1, LFA-1) (Sillerud et al., J. Peptide Res. 62, 2003: 97). We now report the optimization of this peptide by means of single homologous amino acid substitutions to yield a new peptide (IP02-K6; CLLRMKSAC) which shows an approximately sixfold improvement in inhibitory activity of multivalent leukocyte binding (inhibition constant for 50% inhibition, IC50 = 90 microm) compared with IP01 (IC50 = 580 microm). This improvement in activity gives IP02-K6 potent in vivo activity in a murine model of ischemia reperfusion injury (Merchant et al., Am. J. Physiol. Heart Circ. 284, 2003: H1260). In order to determine the structural features relevant to ICAM-1-binding, we have determined the structure of IP02-K6 using proton nuclear magnetic resonance (NMR) spectroscopy and restrained molecular modeling. In our previously reported study of solution models of IP01, we observed three interconverting conformations during low-temperature molecular dynamics simulation. In the present study, we find a single conformation of IP02-K6 similar to one of the previously found conformations of IP01 (family C). In particular, an R4-S7 beta-turn is present in similar proportions in both conformation C of IP01 and in IP02-K6; this motif is important in binding to ICAM-1 because this turn enables the IP02-K6 backbone to drape over proline-36 on ICAM-1. The NMR-derived solution model of IP02-K6 was found to dock at the alphaLbeta2-binding site on ICAM-1 with no changes in peptide backbone conformation. This docking model displaced five of the 15 alphaLbeta2 residues at the ICAM-1-binding site and provided a rationale for understanding the quantitative relationship between IP02-K6 structure and biologic activity.
 ...
PMID:NMR solution structure of a potent cyclic nonapeptide inhibitor of ICAM-1-mediated leukocyte adhesion produced by homologous amino acid substitution. 1535 68


<< Previous 1 2 3 4 5 6 Next >>