Neuronal nitric oxide synthase activation is involved in insulin-mediated cardiovascular effects in the nucleus tractus solitarii of rats.

Neuronal nitric oxide synthases (nNOS) is distributed throughout the central nervous system (CNS) and has been proposed to modulate neuronal activity in the nucleus tractus solitarii (NTS). Here, we investigated whether the activation of nNOS is involved in insulin-induced cardiovascular responses in the NTS. Insulin (100 IU/ml) was unilaterally microinjected into the NTS, and the cardiovascular effects were evaluated before and after microinjection of the nNOS inhibitors 7-nitroindazole (7-NI) (5 pmol) and N(5)-(1-imino-3-butenyl)-l-ornithine (vinyl-L-NIO) (600 pmol). Western blot and immunohistochemical analyses were performed to determine nNOS phosphorylation levels after insulin or phosphoinositide 3-kinase (PI3K) inhibitor LY294002 microinjection into the NTS. Unilateral microinjection of insulin into the NTS produced prominent depressor and bradycardic effects in WKY rats. Pretreatment with the nNOS inhibitors 7-NI and Vinyl-L-NIO attenuated the cardiovascular response evoked by insulin in Wistar-Kyoto (WKY) rats. Moreover, Western blot analysis showed a significant increase in nNOS (16.5+/-0.4-fold; P<0.05; n=4) phosphorylation after insulin injection, whereas the PI3K inhibitor LY294002 abolished the insulin-induced effects. In situ nNOS phosphorylation was found to be increased in the NTS after insulin injection. Furthermore, co-immunoprecipitation assay showed Akt and nNOS can bind to each other as detected by phospho-Akt(S473) and phospho-nNOS(S1416) antibodies. In vitro kinase assay showed insulin activated Akt can directly phosphorylate nNOS(S1416). These results demonstrated that nNOS may couple with the activation of the insulin receptor, via the liberation of NO, in order to participate in central cardiovascular regulation of WKY rats.

A double-blind ambulatory blood pressure monitoring study of the efficacy and tolerability of once-daily telmisartan 40 mg in comparison with losartan 50 mg in the treatment of mild-to-moderate hypertension in Taiwanese patients.

Ambulatory blood pressure monitoring (ABPM) was used to compare the efficacy and tolerability of once-daily telmisartan 40 mg and once-daily losartan 50 mg in Taiwanese patients with mild-to-moderate essential hypertension in a randomised, double-blind, double-dummy, parallel-group study. The initial 2-week placebo run-in phase was followed by randomisation to treatment with telmisartan 40 mg (n = 31) or losartan 50 mg (n = 30) for 6 weeks. The reduction in 18- to 24-h mean (SE) ambulatory diastolic blood pressure (DBP) from baseline was significantly greater with telmisartan 40 mg (-12.1 +/- 1.6 mmHg, p = 0.036) than with losartan 50 mg (-7.0 +/- 1.8 mmHg). The reduction in 18- to 24-h mean (SE) ambulatory systolic blood pressure (SBP) from baseline was also greater with telmisartan 40 mg (-16.0 +/- 2.4 mmHg) than with losartan 50 mg (-11.8 +/- 2.7 mmHg), but did not achieve statistical significance. Telmisartan was well tolerated; no serious adverse events occurred.

Stimulation of the BK(Ca) channel in cultured smooth muscle cells of human trachea by magnolol.

BACKGROUND: Magnolol, a compound isolated from the cortex of Magnolia officinalis, has been found to possess anti-allergic and anti-asthmatic activity. METHODS: The effect of magnolol on ionic currents was studied in cultured smooth muscle cells of human trachea with the aid of the patch clamp technique. RESULTS: In whole cell current recordings magnolol reversibly increased the amplitude of K+ outward currents. The increase in outward current caused by magnolol was sensitive to inhibition by iberiotoxin (200 nM) or paxilline (1 microM) but not by glibenclamide (10 microM). In inside out patches, magnolol added to the bath did not modify single channel conductance but effectively enhanced the activity of large conductance Ca2+ activated K+ (BK(Ca)) channels. Magnolol increased the probability of these channel openings in a concentration dependent manner with an EC50 value of 1.5 microM. The magnolol stimulated increase in the probability of channels opening was independent of internal Ca2+. The application of magnolol also shifted the activation curve of BK(Ca) channels to less positive membrane potentials. The change in the kinetic behaviour of BK(Ca) channels caused by magnolol in these cells is the result of an increase in dissociation and gating constants. CONCLUSIONS: These results provide evidence that, in addition to the presence of antioxidative activity, magnolol is potent in stimulating BK(Ca) channel activity in tracheal smooth muscle cells. The direct stimulation of these BK(Ca) channels by magnolol may contribute to the underlying mechanism by which it acts as an anti-asthmatic compound.

Fenamates stimulate BKCa channel osteoblast-like MG-63 cells activity in the human.

BACKGROUND: The fenamates, a family of nonsteroidal anti-inflammatory drugs that are derivatives of N-phenylanthranilic acid, are the inhibitors of cyclo-oxygenase. The ionic mechanism of actions of these compounds in osteoblasts is not well understood. METHODS: The effects of the fenamates on ionic currents were investigated in a human osteoblast-like cell line (MG-63) with the aid of the whole-cell and inside-out configurations of the patch-clamp technique. RESULTS: In MG-63 cells, niflumic acid and meclofenamic acid increased K+ outward currents (IK). The niflumic acid-stimulated IK was reversed by subsequent application of iberiotoxin or paxilline, yet not by that of glibenclamide or apamin. In the inside-out configuration, niflumic acid (30 micromol/L) added to the bath did not modify single-channel conductance but increased the activity of large-conductance Ca2+-activated K+ (BKCa) channels. The EC50 values for niflumic acid- and meclofenamic acid-induced channel activity were 22 and 24 micromol/L, respectively. Niflumic acid (30 micromol/L) and meclofenamic acid (30 micromol/L) shifted the activation curve of BKCa channels to less positive membrane potentials. Membrane stretch potentiated niflumic acid-stimulated channel activity. The rank order of potency for the activation of BKCa channels in these cells was niflumic acid = meclofenamic acid > tolfenamic acid > flufenamic acid > nimesulide. Evans blue and nordihydroguaiaretic acid increased channel activity; however, indomethacin, piroxicam, and NS-398 had no effect on it. CONCLUSIONS: The fenamates can stimulate BKCa channel activity in a manner that seems to be independent of the action of these drugs on the prostaglandin pathway. The activation of the BKCa channel may hyperpolarize the osteoblast, thereby modulating osteoblastic function.

Transthoracic and transesophageal echocardiographic diagnosis of aneurysm of the sinus of Valsalva: a review of five year experience.

BACKGROUND: Aneurysms of the sinus of Valsalva (SVA) are uncommon congenital lesions. The clinical presentations vary from asymptomatic to progressive heart failure following rupture of the aneurysm into an adjacent cardiac chamber. Retrograde aortogram is the diagnostic tool of choice preoperatively. Recent studies have demonstrated that the SVA can be accurately diagnosed using transthoracic two-dimensional, and color Doppler flow mapping, even for surgical preparation without cardiac catheterization. We report our 5-year experience of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in the evaluation of SVA. METHODS: Eleven adult patients with SVA with or without rupture were studied using both TTE and TEE. All of the diagnoses were subsequently comfirmed by either cardiac catheterization or surgical findings. RESULTS: Aneurysms originated in the right coronary sinus (n = 9) and noncoronary sinus (n = 2); they ruptured into the right ventricle in 5 patients and the right atrium in 5 patients. An unruptured right SVA was noted in 1 patient. Both TTE and TEE could identify the site of the aneurysm, rupture sites, and the receiving chamber equally well. Co-existent cardiac lesions included 11 cases of valvular aortic regurgitation (mild in 7, moderate in 2 and severe in 2). Two cases of perimembranous type ventricular septal defect (VSD) and 6 cases of supracristal type VSD (including 1 case of tetraology of Fallot, 3 supracristal, 1 muscular and 1 subaortic) were noted. Three cases were complicated with valvular vegetations (1 aortic valve, 1 aortic and tricuspid valve and 1 aortic and pulmonic valve). One patient had patent ductus arteriosus and 2 patients had pulmonic valvular stenosis. CONCLUSIONS: TEE provides clearer definition for the detailed anatomy of the ruptured sac and co-existent cardiac lesions than TTE through high resolution and closer approach. We conclude that TEE is a powerful complementary diagnostic tool in the evaluation of patients with SVA. TEE also provides additionally useful information for guiding the surgical approach and for assessing the operative results even without cardiac catheterization.

Rutaecarpine-induced block of delayed rectifier K+ current in NG108-15 neuronal cells.

The effects of rutaecarpine on ionic currents of NG108-15 neuronal cells were investigated in this study. Rutaecarpine (2-100 microM) suppressed the amplitude of delayed rectifier K+ current (I(K(DR))) in a concentration-dependent manner. The IC50 value for rutaecarpine-induced inhibition of I(K(DR)) was 11 microM. I(K(DR)) present in these cells is sensitive to the inhibition by quinidine and dendrotoxin, yet not by E-4031. The presence of rutaecarpine enhanced the rate and extent of I(K(DR)) inactivation, although it had no effect on the initial activation phase of I(K(DR)). Recovery from block by rutaecarpine (5 microM) was fitted by a single exponential with a value of 2.87 s. Crossover of tail currents in the presence of rutaecarpine was also observed. Cell-attached single-channel recordings revealed that rutaecarpine decreased channel activity, but it did not alter single-channel amplitude. With the aid of the binding scheme, a quantitative description of the rutaecarpine actions on I(K(DR)) was provided. However, rutaecarpine (20 microM) had no effect on L-type Ca2+ current. Under current-clamp configuration, rutaecarpine prolonged action potential duration in NG108-15 cells. These results show that rutaecarpine is a blocker of the K(DR) channel. The increase in action potential duration induced by rutaecarpine can be explained mainly by its blocking actions on I(K(DR)).

Comparison of the APACHE II and APACHE III scoring systems in patients with respiratory failure in a medical intensive care unit.

BACKGROUND AND PURPOSE: This retrospective study compared the capability of the Acute Physiology and Chronic Health Evaluation (APACHE) II and APACHE III scoring systems to predict outcome and determined the independent predictors of survival in these scoring systems for patients with respiratory failure in a medical intensive care unit (ICU). MATERIALS AND METHODS: Seven hundred and eight patients with respiratory failure admitted to the medical ICU throughout a 9-year period were studied. Patients with an ICU stay of less than 24 hours, patients under 12 years of age, and burn and surgery patients were excluded. APACHE scores were calculated at 24 hours after admission. Student's t-test was used to compare the total APACHE scores of survivor and non-survivor groups. Multivariate logistic regression analysis was used to determine which variables were predictors of mortality. The discriminative power of APACHE scores to predict in-hospital mortality was studied by the area under the receiver operating characteristic curves of the APACHE II and APACHE III systems, respectively. RESULTS: Both systems showed a significant association between higher scores and higher mortality. The APACHE II system under-predicted the actual hospital mortality rate. The APACHE III systems had a higher discriminative power (area 0.7462) than the APACHE II systems (area 0.6856; p < 0.05). The independent predictors of survival as assessed by APACHE II and III systems were respiratory rate, arterial oxygen pressure, oxygen gradient between alveoli and artery, serum creatinine concentration, and the presence of neurologic abnormalities. CONCLUSIONS: The APACHE III systems has greater discriminative power than the APACHE II systems for predicting in-hospital mortality. The variables of oxygenation, mean artery pressure, respiratory rate, serum creatinine concentration, and Glasgow Coma Scale play important roles in predicting survival for patients with respiratory failure.

Ceramide inhibits the inwardly rectifying potassium current in GH(3) lactotrophs.

The effects of ceramide on ion currents in rat pituitary GH(3) cells were investigated. Hyperpolarization-elicited K(+) currents present in GH(3) cells were studied to determine the effect of ceramide and other related compounds on the inwardly rectifying K(+) current (I(K(IR))). Ceramide (C(2)-ceramide) suppressed the amplitude of I(K(IR)) in a concentration-dependent manner, with an IC(50) value of 5 microM. Ceramide caused a rightward shift in the midpoint for the activation curve of I(K(IR)). Pretreatment with PD-98059 (30 microM) or U-0126 (30 microM) did not prevent ceramide-mediated inhibition of I(K(IR)). However, the magnitude of ceramide-induced inhibition of I(K(IR)) was attenuated in GH(3) cells preincubated with dithiothreitol (10 microM). TNF alpha (100 ng/g) also suppressed I(K(IR)). In the inside-out configuration, application of ceramide (30 microM) to the bath slightly suppressed the activity of large conductance Ca(2+)-activated K(+) channels. Under the current clamp mode, ceramide (10 microM) increased the firing of action potentials. Cells that exhibited an irregular firing pattern were converted to those displaying a regular firing pattern after application of ceramide (10 microM). Ceramide also suppressed I(K(IR)) in neuroblastoma IMR-32 cells. Therefore, ceramide can produce a depressant effect on I(K(IR)). The blockade of this current by ceramide may affect cell function.

Real-time 3-dimensional echocardiographic evaluation of left ventricular volume: correlation with magnetic resonance imaging--a validation study.

BACKGROUND: The purpose of our study was to validate the ability of real-time 3-dimensional echocardiography (RT3D) to measure cardiac volume. METHODS: We studied 25 patients with various cardiac disorders who had a regular heart rhythm and a good precordial echocardiographic window. Each patient underwent complete transthoracic echocardiography (TTE), RT3D, and magnetic resonance imaging (MRI) studies. Left ventricular dimension was calculated from slices of the whole left ventricle obtained by 7 different equidistant azimuth tilts. Planimetry of the endocardial (for volume data) and epicardium (for mass data) surface was performed for each azimuth tilt. The left ventricular end-diastolic volume (LVEDV) and the left ventricular end-systolic volume (LVESV) were calculated. The cardiac mass data were derived with the formula (Epicardial volume - LVEDV) x 1.055. The parameters of LVEDV, LVESV, stroke volume, ejection fraction, and cardiac mass were compared with those derived from MRI. RESULTS: No statistically significant differences were found between the data from RT3D and MRI (P > or =.05). Good correlations were found between these two methods for left ventricle volume and mass measurements (r from 0.92 to 0.99). However, a weaker correlation was found with larger chamber sizes because extrapolation was necessary for the volume of myocardial segments that were not covered by the small sector angle. CONCLUSIONS: For data acquisition, RT3D is faster than either TTE or MRI. It is also better than MRI for measuring cardiac volume and mass. To improve results with larger cardiac chamber sizes, enlargement of the sector angle will be necessary.

Significance of cardiac troponin I and creatine kinase release after coronary intervention.

BACKGROUND: Cardiac troponin I is a highly sensitive and specific marker for early detection of myocardial injury. Whether it can be used to monitor myocardial injury after coronary intervention is uncertain. This study was designed to measure the cardiac troponin I and creatine kinase (CK) after coronary intervention and investigate their clinical significance. METHODS: We measured cardiac troponin I and CK levels before intervention and 4 hours, 8 hours, 12 hours and 24 hours after apparently successful coronary intervention in 106 eligible patients. Nine patients were excluded due to missing data. We also followed up the clinical outcome to record major cardiac events (MACE). RESULTS: The frequency of cardiac troponin I increase after coronary intervention was higher than that of CK increase (40.2% vs 8.2%). The frequency of cardiac troponin I increase in the stent group was significantly higher than that in the PTCA group (49.2% vs 21.9%, p < 0.001). The frequency of cardiac troponin I increase was also higher than that of CK increase in patients with in-hospital events (58.8% vs 14.7%). CONCLUSIONS: Cardiac troponin I is more sensitive than creatine kinase in detecting myocardial injury after coronary intervention. The incidence of cardiac troponin I increase is significantly higher in patients undergoing stenting than in patients treated with balloon angioplasty only. The cardiac troponin I increase is more highly correlated with in-hospital events than is creatine kinase.

Inhibition of large-conductance calcium-activated potassium channel by 2-methoxyestradiol in cultured vascular endothelial (HUV-EC-C) cells.

2-Methoxyestradiol, an endogenous metabolite of 17beta-estradiol, is known to have antitumor and antiangiogenic actions. The effects of 2-methoxyestradiol on ionic currents were investigated in an endothelial cell line (HUV-EC-C) originally derived from human umbilical vein. In the whole-cell patch-clamp configuration, 2-methoxyestradiol (0.3-30 microm) reversibly suppressed the amplitude of K+ outward currents. The IC50 value of the 2-methoxyestradiol-induced decrease in outward current was 3 microm. Evans blue (30 microm) or niflumic acid (30 microm), but not diazoxide (30 microm), reversed the 2-methoxyestradiol-induced decrease in outward current. In the inside-out configuration, application of 2-methoxyestradiol (3 microm) to the bath did not modify the single-channel conductance of large-conductance Ca2+-activated K+ (BKCa) channels; however, it did suppress the channel activity. 2-Methoxyestradiol (3 microm) produced a shift in the activation curve of BKCa channels to more positive potentials. Kinetic studies showed that the 2-methoxyestradiol-induced inhibition of BKCa channels is primarily mediated by a decrease in the number of long-lived openings. 2-Methoxyestradiol-induced inhibition of the channel activity was potentiated by membrane stretch. In contrast, neither 17beta-estradiol (10 microm) nor estriol (10 microm) affected BKCa channel activity, whereas 2-hydroxyestradiol (10 microm) slightly suppressed it. Under current-clamp condition, 2-methoxyestradiol (10 microm) caused membrane depolarization and Evans blue (30 microm) reversed 2-methoxyestradiol-induced depolarization. The present study provides evidence that 2-methoxyestradiol can suppress the activity of BKCa channels in endothelial cells. These effects of 2-methoxyestradiol on ionic currents may contribute to its effects on functional activity of endothelial cells.

Characterization of action potential waveform-evoked L-type calcium currents in pituitary GH3 cells.

The response of the L-type Ca2+ current (ICa,L) in pituitary GH3 cells to variations in the action potential (AP) waveform was examined using the whole-cell configuration of the patch-clamp technique. ICa,L evoked during an AP waveform exhibited an early and a late component. The early component occurred on the rising phase of the AP; the late component coincided with the falling phase. Prolonging the falling phase of the AP increased the Ca2+ charge carried by ICa,L, although the amplitude of the late ICa,L was reduced. Prolonging the peak voltage of the AP waveform, however, increased the amplitude of the late component. ICa,L inactivated during a train of AP waveforms. When Ba2+ was used as the charge carrier, current inactivation during a train of APs decreased. Likewise, ICa,L evoked by the AP templates with irregular bursting pattern was inactivated. When the repetitive firing of APs with depolarizing potentials was replayed to cells, Ca2+ entry was not only spread over the entire AP, but also occurred during the interspike voltage trajectory. After application of thyrotropin releasing hormone (TRH; 10 microM), ICa,L in response to rectangular pulses was increased and the current/voltage relation shifted slightly to more negative values. TRH (10 microM), thapsigargin (10 microM) or cyclopiazonic acid (30 microM) enhanced the late component of the AP-evoked ICa,L. TRH also attenuated the inactivation of ICa,L during a train of APs. These results indicate that in pituitary GH3 cells, the time course and kinetics of ICa,L during the AP waveforms is distinct from that evoked by rectangular voltage clamp. Changes in the shape and firing pattern of APs in GH3 cells can modulate Ca2+ influx through L-type Ca2+ channels. Ca2+ release from internal stores may affect the magnitude of AP-evoked ICa,L in these cells.

A prospective, randomized trial of butyl cyanoacrylate injection versus band ligation in the management of bleeding gastric varices.

Gastric variceal bleeding is a catastrophic event. Both cyanoacrylate injection and banding ligation have been proven to be effective in the management of bleeding gastric varices. This study was performed to compare the efficacy and complications of both the modalities. Cirrhotic patients with a history of gastric variceal bleeding were randomized to 2 groups. The group receiving endoscopic obturation (group A) comprised 31 patients and the group receiving band ligation (group B) comprised 29 patients. Butyl cyanoacrylate and pneumatic-driven ligator were applied, respectively. Treatment was repeated regularly until obliteration of gastric varices. Active bleeding occurred in 15 patients in group A and 11 patients in group B. Initial hemostatic rate (defined as no bleeding for 72 hours after treatment) was 87% in group A and 45% in group B (P = .03). The sessions required to achieve variceal obliteration and obliteration rates were similar in both the groups. However, rebleeding rates were significantly higher in group B (54%) than group A (31%) (P = .0005). Treatment-induced ulcer bleeding occurred in 2 patients (7%) in group A and 8 patients (28%) in group B (P = .03). The amount of blood transfusions required were also higher in group B than group A (4.2 +/- 1.3 vs. 2.6 +/- 0.9 units, respectively) (P < .01). Nine patients of group A and 14 patients of group B died (P = .05). In conclusion, endoscopic obturation using cyanoacrylate proved more effective and safer than band ligation in the management of bleeding gastric varices.

The effects of endoscopic variceal ligation and propranolol on portal hypertensive gastropathy: a prospective, controlled trial.

BACKGROUND: Endoscopic treatment of esophageal varices may accentuate portal hypertensive gastropathy. The impact of the combination of band ligation and propranolol on this condition remains unknown. METHODS: Patients with history of variceal bleeding were randomized to receive band ligation alone (control group, 40 patients) or a combination of band ligation and propranolol (propranolol group, 37 patients). Serial endoscopic evaluation of gastropathy was performed. Gastropathy was classified into 3 grades and scored as 0, 1, or 2. RESULTS: Before endoscopic treatment, 17% of the control group and 22% of the propranolol group had gastropathy (p = 0.78). The occurrence of gastropathy after endoscopic treatment was significantly higher in the control group than in the propranolol group (p = 0.002). Serial endoscopic follow-up revealed that the mean gastropathy score was significantly higher in the control group than in the propranolol group (p < 0.05). In patients with gastropathy the gastropathy score reached a peak at 6 months after endoscopic treatment in both the control and propranolol groups (85% vs. 48%, respectively). After variceal obliteration, accentuation of gastropathy was significant in the control group (p < 0.01) but not in the propranolol group. Gastropathy was less likely to develop in patients who developed gastric varices. Esophageal variceal recurrence was not related to the development of gastropathy after variceal obliteration with banding. Only one patient in the control group bled from gastropathy. CONCLUSION: Band ligation of esophageal varices may accentuate gastropathy, which in this study was partly relieved by propranolol.

Vinpocetine-induced stimulation of calcium-activated potassium currents in rat pituitary GH3 cells.

The effects of vinpocetine, an inhibitor of cyclic GMP phosphodiesterase, on ionic currents were examined in rat pituitary GH3 lactotrophs with the aid of the patch-clamp technique. In GH3 cells bathed in normal Tyrode's solution, vinpocetine (10 microM) reversibly increased the amplitude of Ca2+-activated K+ current (I(K)Ca) with an EC50 value of 4 microM. When the recording pipettes were filled with 10 mM EGTA, vinpocetine also stimulated I(K)Ca. In the cell-attached configuration, application of vinpocetine to the bath increased the activity of large-conductance Ca2+-activated K+ (BK(Ca)) channels. In excised membrane patches, application of vinpocetine (10 microM) to the bath did not change the single-channel conductance of BK(Ca) channels; however, it did increase channel activity. In the inside-out configuration, neither 8-bromo cyclic GMP nor YC-1 applied intracellularly affected BK(Ca) channel activity. The vinpocetine-induced change in the kinetic behavior of BK(Ca) channels was due to an increase in mean open time and a decrease in mean closed time. Vinpocetine (10 microM) caused a leftward shift in the midpoint for the voltage-dependent opening. Under the current-clamp mode, vinpocetine (10 microM) decreased the firing rate of spontaneous action potentials induced by thyrotropin-releasing hormone (10 microM) in GH3 cells. In pheochromocytoma PC12 cells, vinpocetine (10 microM) applied intracellularly also enhanced the activity of BK(Ca) channels without altering single-channel conductance. Thus, the present study suggests that vinpocetine-mediated stimulation of I(K)Ca may result from the direct activation of BK(Ca) channels and indirectly from elevated cytosolic Ca2+.

Prediction of in-hospital mortality in patients with myocardial infarction using APACHE II system.

BACKGROUND: The acute physiology and chronic health evaluation (APACHE) scoring system has been validated in many different patient populations, however, patients with myocardial infarction (MI) were not included in the original data base. To evaluate the ability of APACHE scoring system in predicting in-hospital mortality, 694 patients with MI were studied. METHODS: Data had been collected prospectively in an ICU computer database in the past 3 years. Patients admitted in coronary care unit with acute MI or acute coronary syndrome who had previous history of MI were all included. Patients were divided into survivor and non-survivor data sets. Multiple logistic regression analysis was evaluated on the variables of APACHE II score to determine which variables could predict in-hospital mortality. A logistic regression model was used to study the mortality curves. The differences of APACHE II scores between survivors and non-survivors were compared. Correlation between observed and predicted mortality was also assessed. RESULTS: According to the statistical analysis, the non-survivors tended to have significantly greater APACHE II scores than those of survivors. The APACHE II values of non-survivors and survivors were 23.64 +/- 9.41 versus 13.35 +/- 7.14 (p < 0.001), respectively. Using multiple logistic regression analysis, we found that age, creatinine, coma scale, sodium and APACHE II score were capable of predicting the in-hospital mortality (p < 0.05). With use of the logistic model, a good correlation of predicted mortality rate to observed mortality rate was found (r = 0.992). This study demonstrated that lower APACHE II scores predicted survival while high scores predicted mortality. Mortality rate increased significantly when APACHE II score was > 25. An APACHE II score greater than 28.25 predicted a more than 50% in-hospital mortality. CONCLUSIONS: This study demonstrates that the APACHE II scoring system is capable of predicting mortality in patients with MI, which makes this modality more applicable in the busy intensive care unit.

Plasma endothelin levels are unaltered by thyroid hormone status in humans.

Endothelin is a novel potent vasoconstrictor peptide produced by a wide variety of cell types and which has diverse biological activities. Previously we have reported that thyroid hormone status alters tissue levels of immunoreactive endothelin (irET) in rats. In order to study whether plasma irET levels in humans are affected by thyroid hormone status, we measured irET concentrations by means of radioimmunoassay in plasma samples from euthyroid controls as well as from patients with either hypothyroidism or hyperthyroidism. Plasma samples from the above-mentioned three groups of subjects were collected. After extraction with Sep-Pak C18 cartridges, plasma irET levels were measured by radioimmunoassay. The plasma irET levels in the three groups of subjects did not show any significant difference. Also, no correlations were found between plasma irET levels, thyroid hormones and the thyroid-stimulating hormone thyrotropin (TSH) in euthyroid, hypothyroid and hyperthyroid subjects. These results suggest that thyroid function per se is not a major determinant of plasma irET levels in humans.

Characterization of inhibition by risperidone of the inwardly rectifying K(+) current in pituitary GH(3) cells.

The effects of risperidone on ionic currents in rat pituitary GH(3) cells were investigated with the aid of the patch-clamp technique. Hyperpolarization-activated K(+) currents in GH(3) cells bathed in high-K(+) Ca(2+)-free solution were studied to determine the effect of risperidone and other related compounds on the inwardly rectifying K(+) current (I(K(IR))). Risperidone (0.1-10 microM) suppressed the amplitude of I(K(IR)) in a concentration-dependent manner. The IC(50) value for the risperidone-induced inhibition of I(K(IR)) was 1 microM. Risperidone (3 microM) was found to slow the rate of activation. An increase in current deactivation by the presence of risperidone was also observed. Haloperidol (10 microM) and thioridazine (10 microM) inhibited the amplitude of I(K(IR)) effectively, and clozapine slightly suppressed it; however, metoclopramide (10 microM) had no effect on it. Risperidone (10 microM) had no effect on voltage-dependent K(+) and L-type Ca(2+) currents. However, in the inside-out configuration, risperidone (10 microM) did not alter the single-channel conductance, but reduced the activity of large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels. Under the current-clamp mode, risperidone (3 microM) depolarized the membrane potential and increased the firing rate. With the aid of the spectral analysis, cells that exhibited an irregular firing pattern were also converted to those displaying a regular firing pattern after addition of risperidone (3 microM). The present study provides evidence that risperidone, in addition to the blockade of dopamine receptors, can produce a depressant effect on I(K(IR)) and BK(Ca) channels, and implies that the blockade of these ionic currents by risperidone may affect membrane excitability and prolactin secretion in GH(3) cells.

Dual effect of tamoxifen, an anti-breast-cancer drug, on intracellular Ca(2+) and cytotoxicity in intact cells.

The effect of tamoxifen on Ca(2+) signaling and viability in Madin Darby canine kidney (MDCK) cells was investigated by using fura-2 as a Ca(2+) probe. Tamoxifen evoked a rise in cytosolic free Ca(2+) levels ([Ca(2+)](i)) concentration-dependently between 1 and 50 microM with an EC50 of 10 microM. The response was decreased by extracellular Ca(2+) removal. In Ca(2+)-free medium, pretreatment with 5 microM tamoxifen abolished the [Ca(2+)](i) increase induced by the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin (1 microM), but pretreatment with brefeldin A (50 microM; a Ca(2+) mobilizer of the Golgi complex), thapsigargin (an inhibitor of the endoplasmic reticulum Ca(2+) pump), and carbonylcyanide m-chlorophenylhydrazone (CCCP; a mitochondrial uncoupler), only partly inhibited tamoxifen-induced [Ca(2+)](i) increases. This suggests that tamoxifen released Ca(2+) from multiple pools. Addition of 3 mM Ca(2+) induced a [Ca(2+)](i) rise after pretreatment with 5 microM tamoxifen in Ca(2+)-free medium. Inhibiting inositol 1,4,5-trisphosphate formation with the phospholipase C inhibitor U73122 (2 microM) did not alter 5 microM tamoxifen-induced Ca(2+) release. The [Ca(2+)](i) increase induced by 5 microM tamoxifen was not altered by La(3+), nifedipine, verapamil, or diltiazem. Tamoxifen (1-10 microM) decreased cell viability in a concentration- and time-dependent manner. Tamoxifen (5 microM) also increased [Ca(2+)](i) in neutrophils, bladder cancer cells, and prostate cancer cells from humans and glioma cells from rats. Collectively, it was found that tamoxifen increased [Ca(2+)](i) in MDCK cells by releasing Ca(2+) from multiple Ca(2+) stores in a manner independent of the production of inositol 1,4, 5-trisphosphate and also by triggering Ca(2+) influx from extracellular space. The [Ca(2+)](i) increase was accompanied by cytotoxicity.

Regulation of Ca(2+)-activated K+ currents by ciglitazone in rat pituitary GH3 cells.

BACKGROUND: Ciglitazone, an antidiabetic agent of the thiazolidinedione family, is known to be an activator of the peroxisome-proliferator activator receptor (PPAR)-gamma. The underlying mechanism of ciglitazone actions on ionic currents in neuroendocrine cells remains unclear. METHODS: The effects of ciglitazone on ionic currents were investigated in rat pituitary GH3 cells using the whole-cell and inside-out configurations of the patch-clamp technique. RESULTS: In GH3 cells, ciglitazone at 3-300 mumol/L caused a reversible increase in the amplitude of the Ca(2+)-activated K+ current (IK(Ca)) with a half-maximal concentration of 16 mumol/L. Under the inside-out patch recording mode, ciglitazone applied intracellularly increased the activity of the large-conductance Ca(2+)-activated K+ (BKCa) channels, but did not affect their single-channel conductance. However, troglitazone (30 mumol/L) caused a reduction in the channel activity. The ciglitazone-induced change in the kinetic behavior of BKCa channels is due to an increase in mean open time and a decrease in mean closed time, whereas the troglitazone-induced decrease in the channel activity is related to a decrease in mean open time and an increase in mean closed time. Ciglitazone caused a left shift in the midpoint for voltage-dependent opening. The ciglitazone-stimulated activity of BKCa channels is independent of internal Ca2+. Under the current clamp mode, ciglitazone (30 mumol/L) hyperpolarized the membrane potential. CONCLUSIONS: This study shows that in addition to its activation of PPAR-gamma, ciglitazone can stimulate the activity of BKCa channels expressed in GH3 cells. These effects may affect membrane potentials and contribute to the ciglitazone-induced change in the functional activity of neurons or neuroendocrine cells.