Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The goal of this study was to determine whether protein kinase C mediates bradykinin-induced increases in microvascular permeability. Permeability of the hamster cheek pouch was evaluated using intravital fluorescent microscopy and fluorescein isothiocyanate (FITC)-dextran (MW 70,000). We examined effects of sphingosine, a protein kinase C inhibitor, on bradykinin-induced increases in permeability. Increases in permeability were quantitated by counting the number of leaky sites and calculating the clearance of FITC-dextran. During bradykinin (10(-6) M), leaky sites increased from 0 to 40 +/- 4 (mean +/- SEM) sites/0.11 cm2, and clearance increased from 1.7 +/- 1.0 to 22 +/- 9 ml/sec x 10(-6). The bradykinin type-2 receptor antagonist D-Arg,[Hyp3,Thi5,8,D-Phe7]-bradykinin virtually abolished formation of leaky sites in response to bradykinin. To determine whether changes in microvascular pressure contribute to the increase in leaky sites, venular pressure was measured using a micropipette and survo-null device. Increases in cheek pouch venular pressure were similar during application of bradykinin and adenosine, which increased permeability, and isoproterenol, which did not increase permeability in the cheek pouch. Thus, increases in permeability were not linked to changes in microvascular pressure. The protein kinase C inhibitor, sphingosine (10(-6) M), markedly attenuated responses to bradykinin. Leaky sites increased from 0 to only 2 +/- 1 sites/0.11 cm2, and clearance increased from 3.9 +/- 1.4 to only 6.7 +/- 2.2 ml/sec x 10(-6). To test the specificity of sphingosine, we examined effects of adenosine (10(-6) M). Sphingosine did not significantly alter increases in microvascular permeability in responses to adenosine. We also examined effects of 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), another protein kinase C inhibitor, on responses to bradykinin and adenosine. H-7 greatly attenuated formation of leaky sites during stimulation with bradykinin and did not alter the number of leaky sites produced during adenosine. The findings suggest that protein kinase C may mediate increases in vascular permeability in response to bradykinin.
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PMID:Role of protein kinase C in bradykinin-induced increases in microvascular permeability. 170 11

Proliferating cell nuclear antigen (PCNA) is a co-factor for DNA polymerase delta, which replicates genomic DNA during cell growth and division. Using a monoclonal antibody to PCNA (PC10) and conventional immunofluorescent techniques, we have compared the effect of differentiation stimuli on PCNA expression in normal and HPV immortalised keratinocytes. Two positive nuclear staining patterns were observed, a strong speckled form characteristic of proliferating cells and a weaker diffuse form. Strong nuclear staining was present in 44 +/- 4% (mean +/- SEM) of normal keratinocytes proliferating as a monolayer in 70 microM calcium serum-free medium but decreased to 13 +/- 3% after the differentiation stimulus of 2 mM calcium medium for 2 days. An even greater reduction was observed following other differentiation agents, 1,25 dihydroxyvitamin D3, the phorbol ester TPA and the non-specific protein kinase C inhibitor staurosporine. Transforming growth factor-beta, which slows keratinocyte growth without inducing differentiation, reduced strong staining to 17 +/- 3% of cells, but with an increase in the diffuse pattern of staining from 39 +/- 4 to 57 +/- 3%. HPV immortalised cells were resistant to the above agents except staurosporine, which inhibited growth and reduced the strong nuclear staining from 44 +/- 5% to 15 +/- 2%.
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PMID:Proliferating cell nuclear antigen decreases in normal human keratinocytes with differentiation stimuli but not in an HPV immortalised cell line. 797 77

Macrophage migration inhibitory factor (MIF) is a potent proinflammatory mediator that has been shown to potentiate lethal endotoxemia and to play a potentially important regulatory role in human acute respiratory distress syndrome (ARDS). We have investigated whether eosinophils are an important source of MIF and whether MIF may be involved in the pathophysiology of asthma. Unstimulated human circulating eosinophils were found to contain preformed MIF. Stimulation of human eosinophils with phorbol myristate acetate in vitro yielded significant release of MIF protein. For example, eosinophils stimulated with phorbol myristate acetate (100 nM, 8 h, 37 degreesC) released 1,539+/-435 pg/10(6) cells of MIF, whereas unstimulated cells released barely detectable levels (< 142 pg/10(6) cells, mean+/-SEM, n = 8). This stimulated release was shown to be (a) concentration- and time-dependent, (b) partially blocked by the protein synthesis inhibitor cycloheximide, and (c) significantly inhibited by the protein kinase C inhibitor Ro-31,8220. In addition, we show that the physiological stimuli C5a and IL-5 also cause significant MIF release. Furthermore, bronchoalveolar lavage fluid obtained from asthmatic patients contains significantly elevated levels of MIF as compared to nonatopic normal volunteers (asthmatic, 797.5+/-92 pg/ml; controls, 274+/-91 pg/ml). These results highlight the potential importance of MIF in asthma and other eosinophil-dependent inflammatory disorders.
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PMID:Human circulating eosinophils secrete macrophage migration inhibitory factor (MIF). Potential role in asthma. 963 21

We investigated the role of cAMP/cGMP, protein kinases and intracellular calcium ( [Ca2+]i) in pentoxifylline-stimulated hamster sperm capacitation and the acrosome reaction (AR) in vitro. Treatment with pentoxifylline (0.45 mM) initially increased sperm cAMP values 2.8-fold, compared with untreated controls (396 +/- 9.2 versus 141 +/- 6.0 fmoles/10(6) spermatozoa; mean +/- SEM, n = 6) after 15 min, although by 3 h, cAMP values were similar (503-531 fmoles/10(6) spermatozoa). cGMP values ( approximately 27 fmoles/10(6) spermatozoa) were the same in treated and control spermatozoa. Both sperm capacitation and the AR, determined from the absence of an acrosomal cap, were stimulated by pentoxifylline; these were almost completely inhibited by a Cl-/ HCO3- antiporter inhibitor (4,4-diisothiocyanato-stilbene-2,2 disulphonic acid; 1 mM) defined from the degree of sperm motility and by a protein kinase A inhibitor (H89; 10 microM). A protein kinase C inhibitor (staurosporine, 1 nM) did not affect pentoxifylline-stimulated capacitation but inhibited the AR by 50%. A protein tyrosine kinase inhibitor (tyrphostin A-47, 0.1 mM) had no effect on either pentoxifylline-stimulated capacitation or AR. A phospholipase A2 inhibitor (aristolochic acid, 0.4 mM) markedly inhibited the pentoxifylline-stimulated AR but not capacitation. When intracellular sperm calcium [Ca2+/-]i was measured using fura-2-AM, there was an early rise (271 nM at 0.5 h) in pentoxifylline-treated spermatozoa; this appeared to be due to intracellular mobilization rather than to uptake. In the absence of extracellular Ca2+, sperm motility was maintained in the presence of pentoxifylline, but capacitation did not occur; spermatozoa exhibited a low level of hyperactivated motility and had a poor rate of AR (20.5 +/- 2.3%). These results suggest that: (i) the pentoxifylline-stimulated early onset of sperm capacitation may be mediated by an early rise in cAMP and [Ca2+/-]i and involves protein kinase A activity; and (ii) pentoxifylline-stimulated AR may require phospholipase A2 and protein kinase C activity.
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PMID:Pentoxifylline-stimulated capacitation and acrosome reaction in hamster spermatozoa: involvement of intracellular signalling molecules. 1038 16

To evaluate whether increased levels of reactive oxygen species (ROS) are involved in the pathogenesis of essential hypertension (EH) and non-insulin-dependent diabetes mellitus (NIDDM), both resting and stimulated levels of intracellular ROS were measured in lymphocytes from patients with EH (n = 10), NIDDM (n = 16) and age-matched healthy individuals (control subjects, n = 19). ROS was monitored with the dye, dihydrorhodamine-123 (DHR; 1 micromol/L) in the presence or absence of superoxide dismutase (superoxide scavenger), sodium azide (singlet oxygen/hydrogen peroxide scavenger), genistein (tyrosine kinase inhibitor), or bisindolylmaleimide (protein kinase C inhibitor). Simultaneous monitoring of cytosolic [Ca2+]i was done with fura-2. Resting ROS levels were significantly higher in NIDDM (4.71+/-0.25 nmol/10(6) cells; mean +/- SEM, P<.05) compared with EH (4.03+/-0.22 nmol/10(6) cells) or controls (4.05+/-0.15 nmol/10(6) cells). The formyl-Met-Leu-Phenylalanine-(fMLP)-induced ROS generation was significantly higher in NIDDM (21.92+/-2.23 nmol/10(6) cells; P<.05) compared with EH (14.58+/-1.90 nmol/10(6) cells) or control (16.06+/-1.22 nmol/10(6) cells). The fMLP-induced ROS increase was significantly reduced in the presence of sodium azide in all groups (P<.01) but was largely unaffected in the presence of SOD. Genistein and bisindolylmaleimide significantly inhibited the fMLP-induced ROS in all groups. The fMLP-induced [Ca2+]i increase was significantly higher in NIDDM (71+/-12 nmol/L, P <.01) compared with EH (42+/-4 nmol/L) and control subjects (35+/-3 nmol/L). Phytohemagglutinin was more effective in increasing [Ca2+]i than ROS. It is concluded that ROS may play a role in the metabolic syndrome of NIDDM but not in EH.
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PMID:Reactive oxygen species in essential hypertension and non-insulin-dependent diabetes mellitus. 1061 78

We investigated the combined effect of 5-hydroxytryptamine (5-HT, serotonin) and calcium ionophore (A23187) on human platelet aggregation. Aggregation, monitored at 37 degrees C using a Dual-channel Lumi-aggregometer, was recorded for 5 min after challenge by a change in light transmission as a function of time. 5-HT (2-200 microM) alone did not cause platelet aggregation, but markedly potentiated A23187 (low dose) induced aggregation. Inhibitory concentration (IC50) values for a number of compounds were calculated as means +/- SEM from dose-response determinations. Synergism between 5-HT (2-5 microM) and A23187 (0.5-2 microM) was inhibited by 5-HT receptor blockers, methysergide (IC50 = 18 microM) and cyproheptadine (IC50 = 20 microM), and calcium channel blockers (verapamil and diltiazem, IC50 = 20 microM and 40 microM respectively). Interpretation of the effects of these blockers is complicated by their lack of specificity. Similarly, U73122, an inhibitor of phospholipase C (PLC), blocked the synergistic effect at an IC50 value of 9.2 microM. Wortmannin, a phosphatidylinositide 3-kinase (PI 3-K) inhibitor, also blocked the response (IC50 = 2.6 microM). However, neither genistein, a tyrosine-specific protein kinase inhibitor, nor chelerythrine, a protein kinase C inhibitor, affected aggregation at concentrations up to 10 microM. We conclude that the synergistic interaction between 5-HT and ionophore may be mediated by activation of PLC/Ca2+ and PI 3-kinase signalling pathways, but definitive proof will require other enzyme inhibitors with greater specificity.
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PMID:Second messengers in platelet aggregation evoked by serotonin and A23187, a calcium ionophore. 1172 80