Clinical predictors of complications in patients with left-sided infective endocarditis: A retrospective study of 206 episodes.

PURPOSE: Early identification of specific patient subgroups at high risk of developing life-threatening infective endocarditis (IE) complications is of paramount importance. Better stratification may allow more intensive treatment of these patients and positively influences clinical outcomes. METHODS: We carried out a retrospective survey of consecutive left-sided IE adult patients, admitted over a 15-year period to two main tertiary care centres in the Czech Republic. RESULTS: Among a group of 196 patients (155 males; median age 64 years), a total of 206 left-sided IE episodes were identified. Perivalvular extension of infection was most frequently seen in prosthetic aortic valve endocarditis (OR 6.706, p<0.0001). Valve prolapse/perforation during IE episodes was significantly associated with mitral valve IE (OR 2.136, p=0.026) and vegetation length (OR 1.055, p=0.009). Septic shock was significantly related to two main risk factors: S. aureus infection (OR 8.459, p=<0.0001) and smoking (OR 8.403, p=0.001). Mitral valve IE with a vegetation length ≥13 mm was the strongest risk factor for this complication (OR 3.24, p=0.001), followed by S. aureus infection (OR 3.59, p=0.002). Finally, septic shock (OR 6.000, p=0.001) represented the most important risk factor of in-hospital mortality. CONCLUSIONS: This study provides the most detailed profile of complication predictors related to left-sided IE in Central Europe. Early individual stratification of IE related occurrence of complications might help to decrease extremely high morbidity and mortality of this disease (Tab. 5, Ref. 37).

[Warning about risk of invasive infections in splenectomized patients. Experiences from University Hospital Brno, Czech Republic, in 2011]. / Upozornení na nebezpecí invazivních infekcí u splenektomovaných pacientu. Zkusenosti z FN Brno 2011.

Syndrome of fulminant sepsis in splenectomized (overwhelming postsplenectomy infection - OPSI) is feared and often fatal infectious complication in patients after splenectomy. The risk of syndrome of fulminant sepsis in splenectomized in these persons persists lifelong and doesn't diminish during the time. Etiologically, encapsulated bacterias like Streptococcus pneumoniae, Haemophilus influenzae group b and Neisseria meningitidis are involved. As the mortality of syndrome of fulminant sepsis in splenectomized is very high, it is indispensable to educate and vaccinate persons in risk. The authors present case reports of three splenectomized patients who were hospitalized for invasive pneumococcal infection in the University Hospital Brno, Czech Republic, in 2011.

[Percutaneous coronary interventions in diabetic patients]. / Perkutánní intervencní výkony na vencitých tepnách u diabetiku.

Diabetes mellitus (DM) is a serious medical problem. The patients with diabetes have higher risk of coronary artery diseases. Diabetes mellitus also increases the risk of complication resulting from revascularization treatment in compare with non-diabetic patients. The first studies, which compare the surgical and percutaneous revascularization proved, that the major difference between these two revascularization techniques is in patients with diabetes. The difference is inflected by necessity of repeated revascularization after PCI, which is caused by higher incidence of a restenosis in patients with DM. Mortality, myocardial infarction and stroke are more frequent in diabetic patients, but the difference between PCI and surgical treated groups is not significant. Though the restenosis had significantly decreased due to of drug-eluted stents, the surgical revascularization is preferred method of treatment in patients with insulin-dependent diabetes, poorly compensated diabetes and patients with multiple complex coronary disease.

[Myocardial dysfunction in sepsis--diagnostics and therapy]. / Myokardiální dysfunkce v sepsi--diagnostika a terapie.

Incidence of myocardial dysfunction in studies with severe sepsis patients is up to two thirds of patients. On the other side, patients with normal echocardiography have some type of myocardial injury, which can be detected by elevated serum levels of troponins and natriuretic peptides. Strong prognostic value of these markers regarding morbidity and mortality of septic patients indicates an important role of this "occult" myocardial injury. Therapeutical interventions should take place only in situation in that low cardiac output is not capable to ensure metabolic demands of tissues. Nowadays, because of detrimental effects of classical inotropes, new strategies are under investigation. Namely levosimendan is promising alternative, not only related to its inotropic effects. Early diagnostics, assessment of prognosis and therapeutic strategy in patients with SMD are challenging for continuing research and for clinicians of different specialities.

Time-course of tissue factor plasma level in patients with acute coronary syndrome.

Enhanced expression of tissue factor (TF) may result in thrombosis contributing to acute clinical consequences of coronary artery disease. Several studies demonstrated elevated plasma levels of TF in patients with acute coronary syndrome (ACS). The aim of our study was to compare the concentrations of TF in coronary sinus (CS), proximal part of the left coronary artery (LCA) and peripheral vein (PV) of patients with ACS and stable coronary artery disease (SCAD). Time course of the TF plasma levels in PV was followed on day 1 and day 7 after index event of ACS presentation and was compared to day 0 values. No heparin was given prior to the blood sampling. Twenty-nine patients in the ACS group (age 63.6+/-10.8 years, 20 males, 9 females) and 24 patients with SCAD (age 62.3+/-8.1 years, 21 males, 3 females) were examined. TF plasma level was significantly higher in patients with ACS than in those with SCAD (239.0+/-99.3 ng/ml vs. 164.3+/-114.2 ng/ml; p=0.016). There was no difference in TF plasma levels in PV, CS and LCA (239.0+/-99.3 ng/ml vs. 253.7+/-131.5 ng/ml vs. 250.6+/-116.4 ng/ml, respectively). TF plasma levels tended to decrease only non-significantly on the day 7 (224.4+/-109.8 ng/ml). Significant linear correlation between TF and high sensitivity CRP (hs-CRP) levels on day 0 was found. In conclusion, TF plasma levels are elevated in patients with ACS not only locally in CS but also in systematic circulation. Our data support the relationship between TF production and proinflammatory mediators.

Plasma tissue factor in coronary artery disease: further step to the understanding of the basic mechanisms of coronary artery thrombosis.

Tissue factor is a cell surface protein that is expressed constitutively by monocytes, macrophages and fibroblasts, but also by some other cells in response to a variety of stimuli. The main function of the tissue factor is to form a complex with factor VII/VIIa that converts factors IX and X to their active forms. Tissue factor is also involved in the pathophysiology of systemic inflammatory disorders, coagulopathies, atherosclerotic disease, tumor angiogenesis and metastasis. Increased tissue factor expression either locally in the coronary plaques or systematically on circulating blood elements of patients with acute coronary syndromes may be responsible for increased thrombin generation, thus leading to platelet activation and fibrin formation. Tissue factor therefore plays a pivotal role in the initiation of thrombotic complications in patients with coronary artery disease.

Neuroprotective use of mild hypothermia in patients with severe vasospasms after subarachnoid haemorrhage.

BACKGROUND: The authors describe two cases of patients with a severe subarachnoid haemorrhage, where mild hypothermia was successfully applied as a part of comprehensive neuroprotective therapy. PATIENTS: A 56-year-old patient was admitted to an intensive care unit with the diagnosis of subarachnoid haemorrhage, with a consciousness dysfunction requiring artificial ventilation. Angiography failed to establish the cause of the haemorrhage, even after repeated examinations. Furthermore, the authors describe the case of a 28-year-old woman with negative anamnesis and without long-term pharmacological medication, who was admitted to the hospital with a severe headache and a qualitative consciousness dysfunction. Angiography showed an aneurysm appearing closely above the left internal carotid artery bifurcation. After detecting vasospasms, mild hypothermia was repeatedly used in both patients, keeping the temperature of the body core between 34-34.5 degrees C. RESULTS: The total length of the introduced therapeutic hypothermia was 12 days in the first case and 6 days in the second case. The method used was non-invasive all-body cooling by means of blankets with circulating cooling liquid (Blanketrol II, Cinncinnati Sub Zero). In both cases the computed tomography findings and the clinical conditions gradually improved and the patients were released from the intensive care unit on the 22nd and 30th day, respectively, following the disorder detection. DISCUSSION: Mild hypothermia is a clinically attainable neuroprotective method, which--in combination with other therapeutic measures--led to minimising the neurological deficit in patients with severe subarachnoid haemorrhage (Ref. 11).

Prevalence of normal coronary angiography in the acute phase of suspected ST-elevation myocardial infarction: experience from the PRAGUE studies.

BACKGROUND: Acute ST-elevation myocardial infarction in patients with normal coronary arteries has previously been described, but coronary angiography in these patients was performed after the acute phase of the infarction. It is possible that these patients did not have normal angiograms during the acute phase (transient coronary thrombosis or spasm were usually suspected to be the cause). Information on the prevalence of truly normal coronary angiograms during the acute phase of a suspected ST-elevation myocardial infarction is lacking. PATIENTS AND METHODS: The Primary Angioplasty in patients transferred from General community hospitals to specialized PTCA Units with or without Emergency thrombolysis-1 (PRAGUE-1) and PRAGUE-2 studies enrolled 1150 patients with ST-elevation acute myocardial infarction, in whom 625 coronary angiograms were performed within 2 h of the initial electrocardiogram. A simultaneous registry included an additional 379 coronary angiograms performed during the ST-elevation phase of a suspected myocardial infarction. Thus, a total of 1004 angiograms were retrospectively analyzed. A normal coronary angiogram was defined as one with the absence of any visible angiographic signs of atherosclerosis, thrombosis or spontaneous spasm. RESULTS: Normal coronary angiograms were obtained for 26 patients (2.6%). Among these, the diagnosis at discharge was a small myocardial infarction in seven patients (0.7%), acute (peri)myocarditis in five patients, dilated cardiomyopathy in four patients, hypertension with left ventricular hypertrophy in three patients, pulmonary embolism in two patients and misinterpretation of the electrocardiogram (ie, no cardiac disease) in five patients. Seven patients with small infarctions underwent angiography within 30 min to 90 min of complete relief of the signs of acute ischemia, and thus, angiograms during pain were not taken. None of the 898 patients catheterized during ongoing symptoms of ischemia had a normal coronary angiogram. Spontaneous coronary spasm as the only cause (without underlying coronary atherosclerosis) for the evolving infarction was not seen among these 898 patients. Thus, the causes of the seven small infarcts in patients with normal angiograms remain uncertain. CONCLUSIONS: The observed prevalence of normal coronary angiography in patients presenting with acute chest pain and ST elevations was 2.6%. Most of these cases were misdiagnoses, not infarctions. A normal angiogram during a biochemically confirmed infarction is extremely rare (0.7%) and was not seen during the ongoing symptoms of ischemia.

[Ischemia-modified albumin: new marker of myocardial ischemia?]. / Ischémií modifikovaný albumin: nový marker ischémie myokardu.

The Albumin Cobalt Binding Test is a quantitative in vitro diagnostic test used on human serum that detects ischemia-modified albumin by measuring the cobalt binding capacity of albumin in human serum. Ischemia modified albumin is intended for use in conjunction with ECG and cardiac troponin as an aid to short term risk stratification of patients presenting with chest pain suggestive of cardiac origin. Thus, in patients with chest pain or equivalent symptoms suggestive of cardiac origin, with non-diagnostic ECG and normal troponin, a negative IMA can be used as an aid to rule out acute coronary syndrome (ACS) in low risk patients.

Regulation of interleukin-1-stimulated GMCSF mRNA levels in human endothelium.

The regulation of interleukin-1 (IL-1)-mediated increases in GMCSF mRNA levels in human endothelium was examined and determined to occur in a time- and protein kinase C (PKC)-dependent manner. IL-1beta induced the early activation and translocation of PKC isotypes alpha and beta2 to the nucleus and PKC inhibition attenuated the IL-1-mediated increase in GMCSF mRNA levels. PKC activation by PMA alone, in the absence of IL-1beta activation, however, was insufficient to allow GMCSF mRNA detection. Increasing cyclic adenosine nucleotide (cAMP) levels suppressed IL-1beta-induced increases in GMCSF mRNA levels. In contrast, botulinum toxin C, which mediates the ADP ribosylation of a 21 kD ras-related G protein, augmented IL-1beta-induced GMCSF mRNA expression. Inhibition of protein synthesis (with cycloheximide) raised basal GMCSF mRNA transcripts to detectable levels, augmented IL-1-induced increases in GMCSF mRNA levels, and exhibited negative regulation by cAMP. Finally, disruption of either microtubules (with colchicine) or microfilaments (with cytochalasin B) resulted in reduced GMCSF mRNA expression in response to IL-1beta. These results are compatible with a model wherein IL-1-mediated increases in human endothelial cell GMCSF mRNA may be linked to both nuclear protein kinase C activation and activation of a low molecular weight G-protein, although neither activity alone is sufficient to increase the levels of GMCSF mRNA.

[Ventricular fibrillation in chronic heart disease]. / Komorová fibrilace u chronických onemocnení srdce.

The objective of the work was to describe in subjects with spontaneous ventricular fibrillation, after elimination of acute cardiac disease, the strategy of antiarrhythmic treatment and to evaluate, based on prospective follow-up, the effectiveness of this treatment. The authors included in the group 36 patients (30 men and 6 women) within the range from 34 to 78 years (mean age 58 +/- 11 years) with spontaneous ventricular fibrillation. They divided the group into a subgroup (15 subjects) without revascularization of the heart muscle, into a subgroup (17 subjects) with revascularization of the myocardium (coronary angioplasty and bypasses) and a subgroup (4 subjects) where ischaemic heart disease was ruled out (mostly cardiomyopathies). In all subgroups they used programmed ventricular stimulation (apparatuses of Quinton Co. USA, Biotronik Co. GFR), in the subgroup with revascularization within 3 months. During the diagnostic procedure of ventricular stimulation they tested antiarrhythmic drugs most frequently amiodarone per os (for 4 weeks). An implantable cardioverter--defibrillator was implanted in 17 patients (8 subjects without revascularization, 6 subjects with revascularization, 3 subjects without ischaemic heart disease). All patients were followed up till death, maximum 24 months. The authors evaluated the rate of cardiac deaths (death on cardiac grounds, incl. sudden arrhythmic death) and sudden arrhythmic deaths (within one hour after the onset of symptoms or the first malignant ventricular tachyarrhythmia recorded after implantation of the defibrillator). In the subgroup without revascularization with electric instability of the ventricles according to programmed stimulation 66.7% they described seven cardiac deaths (46.7%) and 6 sudden "arrhythmic" deaths (40%) incl. 5 subjects with ineffective testing of antiarrhythmic drugs. Conversely in the subgroup with revascularization and with diagnostic programmed stimulation in 47.1% they found 3 cardiac deaths (17.7%), one sudden "arrhythmic" death (5.9%)--a subject with ineffective testing. In the subgroup without ischaemic heart disease they recorded cardiac and sudden "arrhythmic" deaths in half the subjects, in all instances in subjects without inducible ventricular tachyarrhythmia. The authors found in the course of a two-year investigation a relapse of cardiac arrest in 25% of subjects after spontaneous ventricular fibrillation. A third of these subjects (all without a cardioverter-defibrillator) died. They confirm the benefit of implantation of a defibrillator for all subjects regardless of the basic diagnosis and revascularization of the heart muscle.

[Changes in platelet activity in invasive cardiologic procedures]. / Zmeny aktivity desticek pri invazivních kardiologických výkonech.

The authors revealed some changes in the platelet activity in patients with invasive cardiological procedures. Changes of the platelet function were manifested by an enhanced aggregation of platelets in vivo, an increased secretion from alpha granules and increased release of prostaglandin metabolites from platelets and from the vascular wall. Acetylsalicylic acid (ASA) suppressed the formation of circulating platelet aggregates in vivo, but the platelet activity was manifested by another mechanism, independent on ASA. The authors recorded therefore an increase of prostaglandin metabolites and PF4 even in patients who were treated with ASA before the invasive examination.

The role of VEGF in the diabetic patients undergoing endovascular therapy of symptomatic aortic valve stenosis.

The aim of this study was to explore changes in plasma vascular endothelial growth factor (VEGF) in aged patients who undergone transcatheter aortic valve implantation or balloon angioplasty for the treatment of aortic stenosis. Plasma VEGF was measured in subjects with diabetes mellitus type 2 (DM) (n=21, age 79.2+/-1.6 years) and in non-diabetic subjects (non-DM) (n=23, age 84.4+/-0.7 years), using an ELISA kit. Before the procedure plasma levels of VEGF were significantly lower in DM than in non-DM patients (P<0.05). Plasma VEGF significantly increased in both groups (DM and non-DM) 24 h (387+/-64 vs. 440+/-30 pg/ml, P<0.05) and 72 h (323+/-69 vs. 489+/-47 pg/ml, P<0.05) after the endovascular procedure. However, the VEGF in DM patients was significantly lower compared to non-DM subjects up to one month after the endovascular procedure (283+/-47 vs. 386+/-38 pg/ml, P<0.05). We conclude that increased plasma VEGF in aged patients associates with atherosclerotic aortic valve stenosis. In spite of that plasma VEGF in DM was constantly significantly lower than in non diabetic patients, both before and after the endovascular procedure, possibly reflecting a disturbance of angiogenic/anti-angiogenic balance in diabetes.

Patient skin dosimetry in interventional cardiology in the Czech Republic.

In this study, skin dosimetry of patients undergoing interventional cardiology procedures is presented. Three hospitals were included. Two methods were used for skin dosimetry--radiochromic dosimetry films and reconstruction of skin dose distribution based on examination protocol. Maximum skin doses (MSD) obtained from both methods were compared for 175 patients. For patients for whom the film MSD was >1 Gy, the reconstruction MSD differed from the film MSD in the range of ± 50 % for 83 % of patients. For remaining patients, the difference was higher and it was caused by longer fluoroscopy time. For 59 patients for whom the cumulative dose was known, the cumulative dose was compared with the film MSD. Skin dosimetry with radiochromic films is more accurate than the reconstruction method, but films do not include X-ray fields from lateral projections whilest reconstructions do.

The role of protein kinase C in alpha-thrombin-mediated endothelial cell activation.

Thrombin, the key regulatory protein of hemostasis, has been implicated in a variety of important endothelial cell processes closely linked to endothelial signal transduction mechanisms. An initial event, following receptor binding by catalytically active alpha-thrombin, appears to be the activation of a G-protein-coupled, PI-specific PLC, with resultant generation of IP3 and DAG, with increases in [Ca2+]i, and activation and translocation of PKC (Fig. 9). PKC activation results in down-regulation of PLC, as demonstrated by inhibition of agonist-induced increases in [Ca2+]i, whereas PLA2 activity is up-regulated, with a resultant increase in endothelial PGI2 synthesis. Recently, we have demonstrated that activity of membrane-bound, endothelial PLD, is also up-regulated by PKC activation. In addition to its modulatory role in endothelial cell phospholipase activities, PKC activation appears to play a critical role in thrombin-mediated endothelial barrier dysfunction, likely via specific cytoskeletal protein phosphorylation. A temporal relationship between alpha-thrombin-mediated signal transduction and specific cellular responses, such as PGI2 synthesis and barrier dysfunction, can be established (Fig. 2). Further investigations are ongoing to identify more clearly the precise biochemical intermediates involved in the endothelial cell response to thrombin, as well as the role of differential phosphorylation by various protein kinase systems in thrombin-mediated signal transduction in vascular endothelium.

Protein kinase C phosphorylates caldesmon77 and vimentin and enhances albumin permeability across cultured bovine pulmonary artery endothelial cell monolayers.

Cytoskeletal protein (CSP) interactions are critical to the contractile response in muscle and non-muscle cells. Current concepts suggest that activation of the contractile apparatus occurs through selective phosphorylation by specific cellular kinase systems. Because the Ca(2+)-phospholipid-dependent protein kinase C (PKC) is involved in the regulation of a number of key endothelial cell responses, the hypothesis that PKC modulates endothelial cell contraction and monolayer permeability was tested. Phorbol myristate acetate (PMA), a direct PKC activator, and alpha-thrombin, a receptor-mediated agonist known to increase endothelial cell permeability, both induced rapid, dose-dependent activation and translocation of PKC in bovine pulmonary artery endothelial cells (BPAEC), as assessed by gamma-[32P]ATP phosphorylation of H1 histone in cellular fractions. This activation was temporally associated with evidence of agonist-mediated endothelial cell contraction as demonstrated by characteristic changes in cellular morphology. Agonist-induced activation of the contractile apparatus was associated with increases in BPAEC monolayer permeability to albumin (approximately 200% increase with 10(-6) MPMA, approximately 400% increase with 10(-8) M alpha-thrombin). To more closely examine the role of PKC in activation of the contractile apparatus, PKC-mediated phosphorylation of two specific CSPs, the actin- and calmodulin-binding protein, caldesmon77, and the intermediate filament protein, vimentin, was assessed. In vitro phosphorylation of both caldesmon and vimentin was demonstrated by addition of exogenous, purified BPAEC PKC to unstimulated BPAEC homogenates, to purified bovine platelet caldesmon77, or to purified smooth muscle caldesmon150. Caldesmon77 and vimentin phosphorylation were observed in intact [32P]-labeled BPAEC monolayers stimulated with either PMA or alpha-thrombin, as detected by immunoprecipitation. In addition, BPAEC pretreatment with the PKC inhibitor, staurosporine, prevented alpha-thrombin- and PMA-induced phosphorylation of both cytoskeletal proteins, attenuated morphologic evidence of contraction, and abolished agonist-induced barrier dysfunction. These results demonstrate that agonist-stimulated PKC activity results in cytoskeletal protein phosphorylation in BPAEC monolayer, an event which occurs in concert with agonist-mediated endothelial cell contraction and resultant barrier dysfunction.

Phosphatidic acid directly activates endothelial cell protein kinase C.

The metabolism of phosphatidic acid (PA) yields diacylglycerol (DAG), a known activator of protein kinase C (PKC). To examine potential direct effects of PA on PKC activation, PKC purified from bovine pulmonary artery endothelial cells (BPAEC) was utilized in an in vitro assay examining gamma-[32P]ATP phosphorylation of H1 histone. In the presence of Ca2+ and phosphatidylserine (PS), DAG (80 microM) produced maximal PKC activity (6.4 pmol gamma-[32P]ATP incorporated/microgram/min). Dioleoyl-PA (80 microM) and 1-stearoyl,2-arachidonyl-PA (80 microM) activated PKC in a concentration-dependent manner (maximal activity of 2.01 +/- 0.1 pmol/microgram/min). Unlike unlabelled phorbol esters or DAG, dioleoyl-PA did not significantly alter the binding of [3H]-phorbol dibutyrate to PKC, suggesting that PA directly activates endothelial cell PKC in a manner distinct from DAG-mediated PKC activation.

Hypoxic pulmonary hypertension: haemodynamic changes after oxygen and various vasodilators in the same patient at different time periods.

The haemodynamic response to oxygen breathing and various vasodilatory drugs (Nifedipine, Ketanserin, Dihydralazine, Nitroglycerin, Iso-Mack, Nit-Ret) was repeatedly measured at different time intervals (4-24 months) in 10 males with hypoxic pulmonary hypertension due to chronic obstructive lung disease. It was found that the pulmonary artery mean pressure and pulmonary vascular resistance changes are stable in most of the patients, discordant reactions being exceptional and of small degree. The authors consider these findings important in the therapeutical decision making for longterm oxygen therapy and or vasodilatory drug administration.

Role of protein kinase C in the regulation of prostaglandin synthesis in human endothelium.

The present study specifically addresses the role of protein kinase C (PKC) activation in human endothelial cell Ca2+ mobilization, a response that is functionally coupled to the production of the potent arachidonate (AA) metabolite, prostacyclin (PGI2). Phorbol 12-myristate 13-acetate (PMA), alpha-thrombin, and sodium fluoride (NaF), a direct G-protein activator, produced a rapid and time-dependent translocation of PKC from the cytosol to the membrane. Activation of PKC by brief pretreatment of human umbilical vein endothelial cell (HUVEC) monolayers with PMA resulted in the inhibition of NaF-induced inositol phosphate increases and attenuation of both alpha-thrombin- and NaF-activated increases in intracellular Ca2+ (Ca2+i). Ca2+ mobilization induced by ionophore A23187 was not affected by PKC preactivation, suggesting PKC-dependent negative feedback inhibition of phosphatidylinositol (PI)-specific phospholipase C (PLC). Agonist-stimulated AA release and PGI2 synthesis in PMA-pretreated cultured human endothelial cells, however, was potentiated, and the enhanced PGI2 synthesis produced by A23187, NaF, and alpha-thrombin was dependent upon the dose of PMA. Treatment of HUVEC monolayers with an intracellular Ca2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N'N'-tetraacetic acid-acetoxymethylester (BAPTA-AM), dramatically reduced alpha-thrombin-, NaF-, and A23187-induced PGI2 synthesis, demonstrating the importance of Ca2+i availability in PGI2 synthesis. BAPTA pretreatment did not inhibit PMA-induced PKC activation, and BAPTA-mediated inhibition of agonist-stimulated PGI2 synthesis was partially attenuated by prior PMA pretreatment. Staurosporine, a potent PKC inhibitor, at concentrations that inhibited PKC-induced phosphorylation of histone-1, augmented both alpha-thrombin- and NaF-induced production of inositol phosphates but markedly inhibited alpha-thrombin-, NaF-, and A23187-induced PGI2 synthesis. The downregulation of PKC activity by prolonged PMA treatment (18 h) produced similar inhibition of PGI2 synthesis by these agonists (approximately 50% inhibition). These studies indicate that the integrated phospholipase A2 and PLC activities are under complex regulation by factors that include both PKC activation and [Ca2+i]. PKC exerts dual effects on prostaglandin synthesis via negative regulation of Gp-coupled PI-specific PLC and positive feedback regulation of AA release and PGI2 synthesis. PKC is thus a critical determinant in the regulation of human endothelial cell prostaglandin synthesis by both receptor-mediated and G-protein-dependent cellular activation.

Interleukin 1 alpha mediated inhibition of myogenic terminal differentiation: increased sensitivity of Ha-ras transformed cultures.

The commitment of myogenically determined cells to terminal differentiation can be modulated by a variety of agents, including growth factors and activated oncogenes. We have examined the effect of interleukin 1 alpha (IL-1 alpha) on the terminal differentiation of a normal myogenically determined cell line and two myogenically determined, differentiation competent cell lines which contain either one or six copies of the activated c-Ha-ras oncogene. Treatment of all cell lines with IL-1 alpha decreased but did not totally inhibit terminal myogenic differentiation. Over the range of IL-1 alpha concentrations assayed (1-40 ng/ml), the c-Ha-ras transformed cell lines demonstrated a significantly greater sensitivity to the inhibitory effects of IL-1 alpha. The inhibition of differentiation was not the result of enhanced proliferation. Interestingly, transformation with activated c-Ha-ras resulted in a decrease in IL-1 alpha receptor number and affinity. The enhanced IL-1 alpha responsiveness of the ras transformants was not the result of increased proliferation or changes in either ras gene expression or protein kinase C activity. IL-1 alpha treatment decreased the steady-state levels of both MyoD1 and myogenin transcripts in the c-Ha-ras transformed but not the normal myogenic cell line. Further studies are required to determine the mechanism(s) responsible for the increased sensitivity of the c-Ha-ras transformed cultures to the inhibitory effects of IL-1 alpha.