Defective phosphatidylinositol 3-kinase signaling in central control of cardiovascular effects in the nucleus tractus solitarii of spontaneously hypertensive rats

Recently we have shown functional involvement of the phosphatidylinositol 3-kinase (PI3K)-Akt-nitric oxide synthase (NOS) signaling pathway in central control of cardiovascular effects in the nucleus tractus solitarii (NTS) of normotensive Wistar-Kyoto (WKY) rats. In this study we determined whether PI3K/Akt signaling was defective in spontaneously hypertensive rats (SHR). WKY rats and SHR were anesthetized with urethane. Mean blood pressure (MBP) and heart rate (HR) were monitored intra-arterially. Unilateral microinjection (60 nL) of insulin (100 IU/mL) into the NTS produced prominent depressor and bradycardic effects in 8- and 16-week-old normotensive WKY and 8-week-old SHR. However, no significant cardiovascular effects were found in 16-week-old SHR after insulin injection. Furthermore, pretreatment with PI3K inhibitor LY294002 and NOS inhibitor L-NAME into the NTS attenuated the cardiovascular response evoked by insulin in WKY and 8-week-old SHR but not in 16-week-old SHR. Unilateral microinjection of 1 mmol/L of PI(3,4,5)P(3) (phosphatidylinositol 3,4,5-triphosphate), a phospholipids second messenger produced by PI3K, into the NTS produced prominent depressor and bradycardic effects in 8- or 16-week-old WKY rats as well as 8-week-old SHR but not in 16-week-old SHR. Western blot analysis showed no significant increase in Akt phosphorylation in 8-week-old pre-hypertensive SHR after insulin injection. Similar results were also found in hypertensive 16-week-old SHR. Our results indicate that the Akt-independent signaling pathway is involved in NOS activation to regulate cardiovascular effects in the NTS of 8-week-old pre-hypertensive SHR. Both Akt-dependent and Akt-independent signaling pathways are defective in hypertensive 16-week-old SHR.

Efficacy and safety of slow-release fluvastatin 80 mg daily in Chinese patients with hypercholesterolemia

BACKGROUND

Before this study, the efficacy and safety of doubling the dosage of fluvastatin from 40 mg/day to 80 mg/day in Chinese patients with primary hypercholesterolemia remained to be determined.

METHODS

In this open-label, active-controlled randomized 2-center study, patients with primary hypercholesterolemia were randomized to treatment with immediate-release fluvastatin 40 mg/day (n = 30) or slow-release fluvastatin 80 mg/day (n = 31) for 12 weeks. The primary efficacy variable was percent change in low-density lipoprotein (LDL) cholesterol level from baseline. Secondary efficacy variables were percent changes in total cholesterol, triglyceride, and high-density lipoprotein (HDL) cholesterol levels, and the percent of patients achieving LDL cholesterol goals of the US National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) II.

RESULTS

Both fluvastatin dosages (40 mg/day vs 80 mg/day) effectively reduced LDL cholesterol (-22.5% vs -29.9%; p = 0.087), total cholesterol (-17.3% vs -22.5%; p = 0.140), and triglyceride levels (-14.0% vs -12.3%; p = 0.813) (all p < 0.0001 for comparison with baseline), and slightly increased HDL cholesterol levels (+5.2% vs +5.6%; p = 0.917), after 12 weeks of treatment. The percent of patients achieving LDL cholesterol goals of the NCEP ATP II was 37% versus 65% (p < 0.05). The adverse event profiles for the 2 fluvastatin dosages were similar.

CONCLUSION

In Chinese patients with primary hypercholesterolemia, doubling the dosage of fluvastatin from 40 to 80 mg once daily was effective and safe regarding reduction of LDL cholesterol level, and allowed more patients to achieve LDL cholesterol goals of the NCEP ATP II.

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.

Cardiac manifestations of relapsing polychondritis--a case report

Relapsing polychondritis is a systemic autoimmune disease that may be associated with inflammatory arthritis, vasculitis, aortitis, and inflammation of the aortic valve and ring. Information describing the cardiac manifestations of relapsing polychondritis is limited. The authors encountered a patient with relapsing polychondritis who had pericardial effusion and aortic valve regurgitation. The patient's history is reported and relevant literatures are reviewed.

Real-time dobutamine stress myocardial contrast echocardiography for detecting coronary artery disease: correlating abnormal wall motion and disturbed perfusion

BACKGROUND

Real-time myocardial contrast echocardiography (MCE) makes possible the simultaneous visualization of changes in perfusion imaging and wall motion.

OBJECTIVES

To assess the accuracy of real-time MCE for detecting the presence and extent of coronary artery disease (CAD), and to evaluate the correlation between wall motion and myocardial perfusion by visual examination.

METHODS

A total of 140 consecutive patients without resting wall motion abnormalities were screened to undergo dobutamine stress MCE with power modulation and coronary angiography. Significant coronary disease was defined by the quantification of over 50% stenosis in a major epicardial vessel. The visual identification of wall motion and myocardial perfusion abnormalities was determined by blind review.

RESULTS

Eight patients were excluded due to suboptimal images (feasibility 94.3%). Myocardial contrast enhancement analysis and wall motion analysis were similar in terms of sensitivity (81.2% versus 83.5%, respectively) and specificity (76.5% versus 80.9%, respectively) in detecting the presence of CAD. Myocardial contrast enhancement analysis tended to have a greater sensitivity than wall motion analysis in detecting the ischemic extent over multiple vascular territories among patients with multiple-vessel disease (sensitivity 83.8% versus 71.4% [P=0.09], and abnormal segment length 54.7+/-21.1% versus 48.9+/-24.7% [P=0.03] for myocardial contrast enhancement and wall motion analysis, respectively). There was good concordance between the presence of myocardial ischemia and wall motion abnormality for the segment-by-segment analysis (89.7% agreement, kappa = 0.745). The correlation of the wall motion score and perfusion score at peak stress was also good (r=0.793, P=0.015).

CONCLUSIONS

Dobutamine stress MCE with power modulation is similar in sensitivity and specificity to wall motion analysis for detecting the presence of CAD. However, it provides greater sensitivity in evaluating the extent of ischemia in patients with multiple-vessel disease.

Prospective and randomized study of the antihypertensive effect and tolerability of three antihypertensive agents, losartan, amlodipine, and lisinopril, in hypertensive patients

We prospectively evaluated the antihypertensive effect and tolerability of three different antihypertensive agents, losartan (angiotensin II receptor blocker), amlodipine (calcium channel blocker), and lisinopril (angiotensin-coverting enzyme inhibitor), in patients with mild-to-moderate hypertension. After a 2-week washout period, 121 patients were randomly allocated to three different groups for 12 weeks. Medications were titrated upward as necessary to achieve the goal office-recorded sitting diastolic blood pressure (SiDBP) (defined as SiDBP <90 mmHg or SiDBP > or = 900 mmHg but with a > or = 10 mmHg drop from baseline). Efficacy and tolerability were assessed after 4, 8, and 12 weeks of therapy with each regimen. At 12 weeks, significant differences in SiDBP compared with data of baseline were noted in all three groups ( P < 0.001 in all comparisons). Similarly, significant differences in the sitting systolic blood pressure compared with baseline data were also seen for all three groups ( P < 0.001 in all comparisons). The number of patients reaching goal SiDBP were comparable for the three groups: 25 patients (62.5%) in the losartan group, 27 patients (67.5%) in the amlodipine group, and 22 patients (59.5%) in the lisinopril group (not significant). Amlodipine produced a more pronounced reduction in SiDBP than the other two medications, although without statistical significance. Patients receiving lisinopril showed a high incidence of coughing (31.7%). Low leg edema was noted only in the amlodipine group (7.5%). Compared with the amlodipine and lisinopril groups, the losartan group seemed to have relatively fewer episodes (7.5%), and fewer patients (three cases) experienced adverse effects. In conclusion, this study demonstrates that losartan has the same antihypertensive effect, but has superior tolerability compared with the other two drugs. Coughing was a common side effect of lisinopril therapy in our population.

Differential effects of quercetin, a natural polyphenolic flavonoid, on L-type calcium current in pituitary tumor (GH3) cells and neuronal NG108-15 cells

The effects of quercetin, a natural polyphenolic compound, on voltage-dependent L-type Ca(2+) current (I(Ca,L)) in rat pituitary GH(3) cells were investigated with the aid of the whole-cell voltage-camp technique. Quercetin (0.5-200 microM) stimulated I(Ca,L) in a concentration-dependent manner. The current-voltage (I-V) relationship of I(Ca,L) was slightly shifted to more negative potentials in the presence of quercetin. The EC(50) value of the quercetin-induced stimulation of I(Ca,L) was about 7 microM. The presence of quercetin (5 microM) shifted the steady state inactivation curve of I(Ca,L) to a more negative potential by approximately -10 mV. Although quercetin might increase intracellular cyclic AMP, sp-cAMPS did not affect I(Ca,L). In addition, neither flavone nor wortmannin had any effect on the amplitude of I(Ca,L), while epicatechin and genistein slightly suppressed it. Quercetin (50 microM) decreased the amplitude of tetrodotoxin-sensitive Na(+) current in GH(3) cells. Under current-clamp configuration, quercetin could increase the firing frequency of actions potentials. Conversely, in NG108-15 neuronal cells, quercetin suppressed the amplitude of I(Ca,L). The quercetin-induced inhibition of I(Ca,L) was abolished in NG108-15 cells preincubated with t-butyl hydroperoxide (1 mM). Quercetin-mediated stimulation of I(Ca,L) in GH(3) cells was presumably not associated with the level of intracellular cyclic AMP, or with the activity of tyrosine or phosphoinositide 3-kinases. Therefore, the effects of quercetin on ion currents may, at least in part, contribute to the underlying mechanisms through which it affects neuronal or neuroendocrine function.

An Outbreak of Food‐borne Illness Due to Methomyl Contamination

BACKGROUND

On December 26, 2002, 124 dinners took ill while eating lunch at a seafood restaurant in the town of Chiching in Kaohsiung municipality of Taiwan. Sixty-nine people were sent to the emergency departments of the Municipal Chiching Hospital and Yuan's General Hospital.

METHODS

We analyzed the clinical symptoms, detailed food history, and ingested amount of each food from 59 hospitalized adult patients and identified the source of the outbreak.

RESULTS

The median latency period from beginning eating to first symptoms was 5 min. Twenty-six symptoms and signs were recorded. The most commonly reported clinical effects were general weakness (84%), ataxia (82%), dizziness (82%), vomiting (80%), sweating (75%), floating sensation (71%), headache (69%), dyspnea (69%), and blurred vision (67%). Thirty-one patients had residual symptoms 7 days after ingestion. Of the six residual symptoms reported, the most frequent ones were dizziness (40%), poor appetite and dry mouth (11%), and gastrointestinal disturbance (11%). The presence of residual symptoms correlated with the severity of the initial complaints (p < 0.01). Almost all patients ate cooked rice (93%) and leaf vegetable stir-fried with crab claw (93%). The amount of each food eaten by the patients was not associated with the severity of symptoms (p > 0.05). High levels of methomyl in leaf vegetables of "leaf vegetables stir-fried with crab claws" (380 ppm) and fried mussels (1113 ppm) were found by the Food Inspection Center at the Department of Health. The food history and chemical analysis of the poison indicated methomyl was the cause of this outbreak. Twenty-four patients recovered completely within 7 days.

CONCLUSION

Food-related methomyl intoxication produced a rapid onset of significant clinical toxicity in 124 individuals. Based on the analysis of 55 adult patients, the most common effects were gait ataxia, dizziness, generalized weakness, and vomiting.

Effect of arvanil (N-arachidonoyl-vanillyl-amine), a nonpungent anandamide-capsaicin hybrid, on ion currents in NG108-15 neuronal cells

The effects of arvanil (N-arachidonoyl-vanillyl-amine), a structural hybrid between capsaicin and anandamide, on ion currents in a mouse neuroblastoma and rat glioma hybrid cell line, NG108-15, were examined with the aid of the whole-cell voltage-clamp technique. Arvanil (0.2-50 microM) caused an inhibition of voltage-dependent L-type Ca(2+) current (I(Ca,L)) in a concentration-dependent manner. Arvanil produced no change in the overall shape of the current-voltage relationship of I(Ca,L). The IC(50) value of arvanil-induced inhibition of I(Ca,L) was 2 microM. Arvanil (5 microM) could shift the steady-state inactivation curve of I(Ca,L) to a more negative potential by approximately -15mV. No effect of arvanil (20 microM) on delayed rectifier K(+) current (I(K(DR))) was observed; however, capsaicin (20 microM), glyceryl nonivamide (20 microM) and capsinolol (20 microM) suppressed it significantly. Arvanil (20 microM) caused a slight reduction in the amplitude of erg (ether-à-go-go-related)-mediated K(+) current (I(K(erg))) without modifying the activation curve of this current, while capsaicin and glyceryl nonivamide were more effective in suppressing I(K(erg)). Under current-clamp configuration, arvanil decreased the firing frequency of action potentials. Arvanil-mediated inhibition of I(Ca,L) appeared to be independent of its binding to either vanilloid or cannabinoid receptors. The channel-blocking properties of arvanil may, at least in part, contribute to the underlying mechanisms by which it affects neuronal or neuroendocrine function.

Behavior of nonselective cation channels and large-conductance Ca2+-activated K+ channels induced by dynamic changes in membrane stretch in cultured smooth muscle cells of human coronary artery

INTRODUCTION

The effects of membrane stretch on ion channels were investigated in cultured smooth muscle cells of human coronary artery.

METHODS AND RESULTS

In the cell-attached configuration, membrane stretch with negative pressure induced two types of stretch-activated (SA) ion channels: a nonselective cation channel and a large-conductance Ca2+-activated K+ (BK(Ca)) channel. The single-channel conductances of SA cation and BK(Ca) channels were 26 and 203 pS, respectively. To elucidate the mechanism of activation of these SA channels and to minimize mechanical disruption, a sinusoidal change in pipette pressure was applied to the on-cell membrane patch. During dynamic changes in pipette pressure, increases in SA cation channel activity was found to coincide with increases in BK(Ca) channel activity. In the continued presence of cyclic stretch, the activity of SA cation channels gradually diminished. However, after termination of cyclic stretch, BK(Ca) channel activity was greatly enhanced, but the activity of SA cation channels disappeared.

CONCLUSION

This study is the first to demonstrate that the behavior of SA cation and BK(Ca) channels in coronary smooth muscle cells is differentially susceptible to dynamic changes in membrane tension.

Stimulatory effects of squamocin, an Annonaceous acetogenin, on Ca(2+)-activated K+ current in cultured smooth muscle cells of human coronary artery

The patch-clamp recording technique was used to investigate the effect of squamocin, an Annonaceous acetogenin, on ion currents in cultured smooth muscle cells of human coronary artery. In whole-cell configuration, squamocin (0.3-100 microM) induced Ca(2+)-activated K+ current [IK(Ca)] in a concentration-dependent manner with an EC50 value of 4 microM. Squamocin-stimulated IK(Ca) was suppressed by iberiotoxin (200 nM), paxilline (1 microM), or tetraethylammonium chloride (5 mM), yet not by apamin (200 nM) or glibenclamide (10 microM). In cells dialyzed with 10 mM EGTA, this compound had little effect on IK(Ca). When cells were exposed to Ca(2+)-free solution, squamocin (3 microM) induced a transient increase in IK(Ca). In continued presence of squamocin, an additional increase in extracellular Ca2+ (1 mM) caused a significant increase in IK(Ca). Pretreatment with carbonyl cyanide m-chlorophenyl hydrazone (CCCP; 3 microM) for 5 h did not alter the magnitude of squamocin-induced IK(Ca). However, squamocin (30 microM) suppressed the amplitude of voltage-dependent L-type Ca2+ current. In cell-attached configuration of single-channel recordings, squamocin applied to the bath increased the activity of large-conductance Ca(2+)-activated K+ (BKCa) channels without altering single-channel conductance. Conversely, in inside-out patches, squamocin applied to the intracellular surface had no effect on BKCa channel activity, whereas niflumic acid increased it effectively. These findings provide the evidence that squamocin can activate IK(Ca) in coronary arterial smooth muscle cells. Initial transient activation of IK(Ca) may reflect the squamocin-induced Ca2+ release from intracellular Ca2+ stores, whereas the sustained activation of IK(Ca) may arise from the squamocin-induced Ca2+ influx across the cell membrane. The stimulatory effect of squamocin on these channels should affect the functional activity of vascular smooth muscle cells.

Novel effect of carvedilol on Ca2+ movement in renal tubular cells

The effect of carvedilol on intracellular free Ca(2+) levels ([Ca(2+)](i)) has not been explored previously. This study was aimed to examine the effect of carvedilol on Ca(2+) handling in renal tubular cells. Madin-Darby canine kidney cells were used as a model for renal tubular cells and fura-2 was used as a fluorescent Ca(2+) probe. Carvedilol increased [Ca(2+)](i) in a concentration-dependent manner with an EC(50) value of 5 microM. Extracellular Ca(2+) removal partly inhibited the [Ca(2+)](i) signals. Carvedilol-induced Ca(2+) influx was verified by measuring Mn(2+)-induced quench of fura-2 fluorescence. Carvedilol-induced store Ca(2+) release was reduced by pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor) but not with 5 microM ryanodine or 2 microM carbonylcyanide m-chlorophenylhydrazone (a mitochondrial uncoupler). Carvedilol (30 microM)-induced Ca(2+) release was not affected by inhibiting phospholipase C with 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-l)amino)hexyl)-1H-pyrrole-2,5-dione (U73122; 2 microM), but was potentiated by increasing cAMP levels or inhibiting protein kinase C. The carvedilol-induced Ca(2+) mobilization was not significantly sequestered by the endoplasmic reticulum or mitochondria. This study shows that carvedilol increased [Ca(2+)](i) in renal tubular cells by causing Ca(2+) release from the endoplasmic reticulum and other unknown stores in an inositol-1,4,5-trisphosphate-independent manner, and by inducing Ca(2+) influx. The Ca(2+) release was modulated by cAMP and protein kinase C.

Long-term clinical follow-up after successful direct coronary stenting without predilatation

BACKGROUND

Direct stent implantation without predilatation is considered a promising new technique that may reduce procedural time, radiation exposure, ischemic time and cost, but little information is available concerning the long-term outcome. The aim of this study was to investigate the long-term clinical outcome of successful direct stenting without predilatation.

METHODS

We prospectively undertook a clinical follow-up program (minimum 8 months) in a consecutive series of 101 patients (113 lesions) who were successfully treated with direct stenting without predilatation.

RESULTS

Clinical follow-up was obtained in all 101 patients at a mean period of 12.8 months (range 8 to 18.9). Stress test results were available in 94 patients (94%). During the follow-up period, 23 patients (23%) had one or more events, which included death in 2 patients (2%), target vessel revascularization in 14 (14%), myocardial infarction in 1 (1%) and positive stress test results or recurrence of symptoms (Canadian Cardiovascular Society I to II) treated medically in 6 (6%). Cumulative event-free survival at 8 and 18 months were 80% and 72%, respectively. Long-term clinical event rate was not significantly different among the clinical presentations, lesion types, or stent types. Angiographic follow-up was performed in 43 (43%) patients with 45 lesions. Restenosis (defined as 50% diameter stenosis) was observed in 14 of the lesions (31%).

CONCLUSIONS

Direct stenting without predilatation is an effective method of coronary intervention in terms of low long-term clinical event rate.

Initial experience of using color kinesis in the diagnosis of coronary artery disease

BACKGROUND

Color kinesis (CK) is a recently developed echocardiographic technique. This report describes our initial effort in the validation of the use of CK for the diagnosis of coronary artery disease (CAD).

METHODS

Two-dimensional (2-D) echocardiography and CK were studied in 30 normal subjects and 24 CAD patients. Coronary angiography was performed in the 24 patients. Significant (> 70% luminal diameter stenosis) CAD was present in 18 patients (79%), all of whom had history of myocardial infarction. Regional fractional area change in each segment was displayed as a stacked color histogram. The histograms derived from these 30 normal subjects were averaged to obtain the normal pattern of left ventricular contraction; the mean value +/- 1 SD was considered the reference histogram. When the regional fractional area change deviated from this normal reference, this segment was considered as having regional wall motion abnormality. The detection of wall motion abnormalities by visual interpretation of 2-D echocardiography, reviewing the CK loop recording, and CK stacked histograms were compared. To assess the relationship of measurement of endocardial excursion of CK images, the width of the color band was measured at the midpoint of each segment along a line perpendicular to the cardiac border. The endocardial excursion measured by 2 independent observers was compared using linear regression analysis and calculation of intraclass correlation coefficient.

RESULTS

The sensitivity and specificity for detection of CAD were 77.8% and 66.6%, respectively, for CK loop reviewing, 83.3% and 66.7% for CK stacked histogram analysis, and 77.8% and 83.3% for 2-D echocardiography. The overall accuracies for CAD detection were 75% for CK loop reviewing, 79.2% for CK stacked histogram analysis, and 79.2% for the 2-D echocardiography (not significant in all comparisons). The correlation of measurement of endocardial excursion from the CK images by 2-observers was good (r = 0.85, p < 0.01), and intraclass correlation coefficient was 0.99 (p < 0.0001).

CONCLUSIONS

Our data demonstrate that both the CK loop reviewing and stacked histogram analysis were comparable to 2-D echocardiography for detecting CAD.

Prone-position ventilation induces sustained improvement in oxygenation in patients with acute respiratory distress syndrome who have a large shunt

OBJECTIVES

Prone-position ventilation (PPV) induces acute improvement in oxygenation in many patients with acute respiratory distress syndrome (ARDS), with some maintaining their oxygenation even after they were returned to the supine position, but it is unclear what clinical factors determine the sustained oxygenation benefit. We hypothesized that patients with ARDS who have a larger shunt would have a better acute and sustained oxygenation response to PPV.

DESIGN

Prospective, nonrandomized interventional study.

SETTING

Medical and surgical intensive care units, university tertiary care center.

PATIENTS

Twenty-two consecutive patients, with ARDS with an average PaO2/FiO2 of 94, were administered PPV for 12 hrs followed by supine-position ventilation for 2 hrs.

MEASUREMENTS

Hemodynamic and gas exchange variables were monitored. The shunt was measured as venous admixture at an FiO2 of 1.0, and compliances of the respiratory system, lung, and chest wall were measured by the esophageal balloon technique before PPV, during PPV, and during subsequent supine-position ventilation.

MAIN RESULTS

Fourteen patients (64%) responded to PPV, with PaO2/FiO2 increasing by > or =20. These changes were associated with a decrease in chest wall compliance. Responders had significantly shorter time from ARDS to PPV, a lower baseline PaO2/FiO2, and a higher venous admixture. All responders maintained the improvement in oxygenation and had a greater respiratory system compliance after returning to the supine position. Time from ARDS to PPV and baseline lung injury score were negatively associated, whereas chest wall compliance, heart rate, and PaCO2 were positively associated with sustained improvement in oxygenation.

CONCLUSIONS

PPV induced acute and sustained improvement in oxygenation in many patients with ARDS. The sustained improvement is more significant if PPV is administered early to patients with a larger shunt and a more compliant chest wall. Measuring venous admixture and chest wall compliance before PPV may help select a subgroup of patients with ARDS who may benefit the most from PPV.

Block of L-type Ca2+ current by beauvericin, a toxic cyclopeptide, in the NG108-15 neuronal cell line

The effects of beauverficin, a cyclodepsipeptide compound, on ion currents in a mouse neuroblastoma and rat glioma hybrid cell line, NG108-15, were investigated with the aid of the whole-cell voltage-clamp technique. Beauvericin (0.3-100 microM) reversibly produced an inhibition of L-type voltage-dependent Ca2+ current (I(Ca,L)) in a concentration-dependent manner. Beauvericin caused no change in the overall shape of the current-voltage relationship of I(Ca,L). The IC(50) value of beauvericin-induced inhibition of I(Ca,L) was 4 microM. Neither gabapentin (30 microM) nor omega-conotoxin GVIA (3 microM) had effects on I(Ca,L). Beauvericin (30 microM) shifted the steady-state inactivation curve of I(Ca,L) to more negative membrane potentials by approximately -15 mV. The inhibitory effects of beauvericin on I(Ca,L) exhibited tonic and use-dependent characteristics. Beauvericin also suppressed I(Ca,L) evoked by repetitive action potential waveforms effectively. However, beauvericin (30 microM) had no effect on delayed rectifier K+ current in NG105-18 cells. Under current-clamp configuration, beauvericin reduced the firing frequency of action potentials. Therefore, this study indicates that beauvericin is a relatively specific inhibitor of L-type Ca2+ current in NG108-15 cells.

Echocardiographic features of primary cardiac sarcoma

Primary cardiac sarcoma is extremely rare and seldom causes symptoms until late in its course. Discomfort may occur only when the mass causes obstruction to the intracardiac flow. Early diagnosis is vital because it allows prompt and relevant management. We describe the history and echocardiographic features in four patients with primary cardiac sarcoma and review the current literature.

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)).

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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+.

Characterization of ATP-sensitive potassium channels functionally expressed in pituitary GH3 cells

ATP-sensitive K+ (KATP) channels have been characterized in pituitary GH3 cells with the aid of the patch-clamp technique. In the cell-attached configuration, the presence of diazoxide (100 microM) revealed the presence of glibenclamide-sensitive KATP channel exhibiting a unitary conductance of 74 pS. Metabolic inhibition induced by 2,4-dinitrophenol (1 mM) or sodium cyanide (300 microM) increased KATP channel activity, while nicorandil (100 microM) had no effect on it. In the inside-out configuration, Mg-ATP applied intracellularly suppressed the activity of KATP channels in a concentration-dependent manner with an IC50 value of 30 microM. The activation of phospholipase A2 caused by mellitin (1 microM) was found to enhance KATP channel activity and further application of aristolochic acid (30 microM) reduced the mellitin-induced increase in channel activity. The challenging of cells with 4,4'-dithiodipyridine (100 microM) also induced KATP channel activity. Diazoxide, mellitin and 4,4'-dithiodipyridine activated the KATP channels that exhibited similar channel-opening kinetics. In addition, under current-clamp conditions, the application of diazoxide (100 microM) hyperpolarized the membrane potential and reduced the firing rate of spontaneous action potentials. The present study clearly indicates that KATP channels similar to those seen in pancreatic beta cells are functionally expressed in GH3 cells. In addition to the presence of Ca(2+)-activated K+ channels, KATP channels found in these cells could thus play an important role in controlling hormonal release by regulating the membrane potential.

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.

Computerized-tomography-guided percutaneous tumor ablation using acetic acid injection in an aldosterone-producing tumor--a novel therapy

We report the first case of an adrenocortical tumor that was successfully ablated using computerized tomography (CT)-guided percutaneous acetic acid injection. A 57-year-old woman presented with recurrent sudden onset of general weakness, polyuria, hypokalemia and low plasma renin activity with a high aldosterone level. The computerized tomogram and sonogram of the abdomen demonstrated a well-defined low-density tumor in the right adrenal gland. Under CT guidance, we successfully ablated the tumor using percutaneous acetic acid injection. This procedure took only 40 minutes and required only local anesthesia. The patient was up and walking the following day. During the next 2 years of clinical follow-up, there was no evidence of tumor recurrence.

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.

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.

Actions of epoxyeicosatrienoic acid on large-conductance Ca(2+)-activated K(+) channels in pituitary GH(3) cells

Epoxyeicosatrienoic acids (EETs), a family of cytochrome P450 epoxygenase metabolites of arachidonic acid, are believed to have an autocrine or paracrine role in the regulation of neurons or neuroendocrine cells. The effects of 14,15-EET on ionic currents were investigated in rat pituitary GH(3) cells. In the whole-cell configuration, 14,15-EET (3 microM) reversibly increased the amplitude of the Ca(2+)-activated K(+) current (I(K(Ca))). The 14, 15-EET-induced increase in I(K(Ca)) was unaffected in the presence of 10 microM thyrotropin-releasing hormone externally or 10 microM inositol trisphosphate in the recording pipette. In cells preincubated with pertussis toxin or herbimycin A, the 14, 15-EET-induced increase in I(K(Ca)) was also not changed. In the inside-out configuration, 14,15-EET applied intracellularly did not change single-channel conductance, but did increase the opening probability of large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels. 14,15-EET (3 microM) shifted the activation curve of BK(Ca) channels to less positive membrane potential by approximately 15 mV. The change in the kinetic behavior of BK(Ca) channels caused by 14,15-EET is explained by a lengthening of open and a shortening of closed times. 14,15-EET increased the activity of BK(Ca) channels in a concentration-dependent manner with an EC(50) value of 1 microM. However, 14,15-EET did not affect the Ca(2+) sensitivity of BK(Ca) channels. The present study indicates that 14,15-EET is an opener of BK(Ca) channels in GH(3) cells and that the stimulatory effect of 14, 15-EET on these channels may, at least in part, contribute to the underlying cellular mechanisms by which EETs affect neuronal or neuroendocrine function.

A left atrial thrombus is not an absolute limitation to balloon mitral commissurotomy for patients with mitral stenosis. a serial transesophageal echocardiographic study

Previous reports did not encourage balloon mitral commissurotomy (BMC) when left atrial (LA) thrombi were located beyond LA appendage. We hypothesize that LA thrombi may be resolved in some patients after anticoagulant therapy, and BMC can be performed subsequently. In the present study, we used transesophageal echocardiography (TEE) to evaluate the effects of anticoagulant on LA thrombi in patients with mitral stenosis, to compare the clinical differences between patients with (group A) and without (group B) resolution of LA thrombi, and to evaluate the safety of subsequent BMC in these patients. TEE was performed on 190 consecutive patients with mitral stenosis; 14 (7.4%) of them were found with LA thrombi. Serial TEE was performed and optimal anticoagulant therapy was achieved in all 14 patients. The thrombi were located within the LA appendage in 6 cases, attached to the LA posterior wall in 5, posterior wall and interatrial septum in 1, and LA appendage and posterior wall in 2. Based on the 6-month TEE follow-up, we found that the LA thrombi disappeared in 8 (57.2%) patients (group A) and persisted in 6 patients (group B). LA thrombi resolved within 3 months in 7 group A patients (87.5%). Furthermore, the resolution of LA thrombi was more frequently observed in patients either with a smaller LA dimension (51.9 +/- 3.4 vs. 57.8 +/- 4.8 mm, p = 0.02) or with their thrombi located inside their LA appendage (p = 0.03). No differences in other clinical and echocardiographic variables were noted between these two groups. Subsequently, group A patients underwent BMC without complications of systemic embolization. In conclusion, LA thrombi can be resolved after optimal anticoagulant therapy in a considerable proportion of patients with mitral stenosis. Serial TEE studies are helpful to observe LA thrombus resolution; they may also be useful in planning the treatment strategy.

Novel effects of clotrimazole on Ca2+ signaling in Madin Darby canine kidney cells

The effect of clotrimazole on Ca2+ signaling in Madin Darby canine kidney (MDCK) cells was investigated by using fura-2 as a Ca2+ indicator. Clotrimazole (1-30 microM) induced a concentration-dependent [Ca2+]i increase. The [Ca2+]i increase comprised an initial rise and a slow decay. External Ca2+ removal partly inhibited the Ca2+ signals by reducing both the initial rise and the decay phase, indicating that clotrimazole triggered both Ca2+ influx and Ca2+ release. Pretreatment with 30 microM clotrimazole in Ca2+-free medium abolished the Ca2+ release induced by thapsigargin (1 microM), an endoplasmic reticulum Ca2+ pump inhibitor, and conversely, pretreatment with thapsigargin prevented clotrimazole from releasing more Ca2+. This suggests that the thapsigargin-sensitive Ca2+ store is the source of clotrimazole-induced Ca2+ release. Clotrimazole (10 microM) triggered Mn2+ quench of fura-2 fluorescence which was partly inhibited by 1 mM La3+. Addition of 3 mM Ca2+ induced a [Ca2+]i increase after preincubation with 10 microM clotrimazole in Ca2+-free medium, indicating that clotrimazole activated capacitative Ca2+ entry. However, 10 and 30 microM clotrimazole inhibited 1 microM thapsigargin-induced capacitative Ca2+ entry by 21% and 74%, respectively. Pretreatment with 40 microM aristolochic acid to inhibit phospholipase A2 reduced 30 microM clotrimazole-induced Ca2+ release by 51%, but inhibiting phospholipase C with 2 microM U73122 had little effect. This implies that clotrimazole induces Ca2+ release in an IP3-independent manner, which could be modulated by phospholipase A2-coupled events.

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.

Modulatory effects of carbon monoxide on baroreflex activation in nucleus tractus solitarii of rats

Recent studies suggest that carbon monoxide (CO), which is produced in significant quantities in many brain regions, may function as a neurotransmitter. Heme oxygenase catalyzes the metabolism of heme to CO and biliverdin; however, the physiological role of CO in central cardiovascular regulation was not well understood. In the present study, we evaluated the baroreflex response of CO in the nucleus tractus solitarii (NTS) of rats. Male Sprague-Dawley rats were anesthetized with urethane, and blood pressure and heart rate were monitored intra-arterially. Unilateral microinjection (60 nL) of hematin, a heme molecule cleaved by heme oxygenase to yield CO, into the NTS produced prominent dose-related depressor and bradycardic effects. Baroreflex responses were elicited by increasing doses of phenylephrine (10 to 30 microg/kg IV) before and after intra-NTS administration of zinc deuteroporphyrin 2,4-bis-glycol (ZnDPBG) (1 nmol), an inhibitor of heme oxygenase activity, or vehicle alone. The reflex bradycardia elicited by phenylephrine was significantly inhibited by pretreatment with ZnDPBG. Furthermore, the inhibitory effect of ZnDPBG on baroreflex activation was dose dependent. These results suggest CO formed by brain heme oxygenase plays a significant role in central cardiovascular regulation and that inhibition of heme oxygenase attenuated baroreflex activation.

The cause of slowed forearm median conduction velocity in carpal tunnel syndrome

OBJECTIVES

Attempting to answer a debate concerning the etiopathogenesis of the decreased forearm median motor conduction velocity (FMMCV), we tried to use proximal stimulation at the wrist, elbow, mid-arm and axillary regions to determine segmental median motor conduction velocity (MMCV). We also correlated the FMMCV with median motor distal latency (MMDL) and compound muscle action potential (CMAP) amplitudes of the abductor pollicis brevis (APB) muscle in order to assess whether the conduction block of large myelinating fibers or retrograde axonal atrophy was the major cause of the decreased FMMCV.

BACKGROUND

The cause of the decreased FMMCV resulting from either the conduction block of the large myelinating fibers at the wrist or distal compression with retrograde axonal atrophy remains an unresolved issue at the moment. Animal models have supported the hypothesis that the retrograde axonal atrophy might also occur in humans. Other authors believe the standard FMMCV is calculated by subtracting the distal latency which may not represent an exact assessment of FMMCV but rather the velocity of small fibers that persist through the carpal tunnel.

SUBJECTS AND METHODS

Patients with the clinical symptoms and signs of carpal tunnel syndrome (CTS) confirmed using standard electrodiagnosis were included. The patients were arbitrarily divided into two groups based on the FMMCV, one with reduced FMMCV (n = 20, FMMCV < 50 m/s) and the other with normal FMMCV (n = 35, FMMCV> or =50 m/s). Age-matched volunteers served as controls. We explored motor conduction proximally at wrist, elbow, mid-arm and axillary stimulation, and recorded at the APB muscles. Based on the latency differences, we calculated the FMMCV, distal arm MMCV (DAMMCV) and proximal arm MMCV (PAMMCV), and compared the conduction velocity (CV) differences of DAMMCV-FMMCV, PAMMCV-FMMCV and PAMMCV-DAMMCV in the two patient groups and the control. Furthermore, we correlated FMMCV with MMDL and CMAP amplitudes of APB muscle because MMDL and CMAP amplitudes might reflect the integrity of the large myelinating fibers.

RESULTS

CMAP amplitudes of APB muscle at wrist stimulation and MMDL were not correlated with FMMCV in either of the two patient groups; however, the CMAP amplitude was markedly decreased and MMDL was significantly prolonged when compared with normal controls. The significant increase of CV gradient of DAMMCV-FMMCV and PAMMCV-FMMCV without an equal increase of CV gradient of PAMMCV-DAMMCV only occurred in the reduced FMMCV patient group, suggesting that the conduction block is not the primary cause. The CV gradient of DAMMCV-FMMCV and PAMMCV-DAMMCV did not show any significant difference between patients with the normal FMMCV and the control group.

CONCLUSION

The retrograde axonal atrophy, not selective damage of the large fibers at the wrist, was the direct cause of the decreased FMMCV.

Stimulatory effects of delta-hexachlorocyclohexane on Ca(2+)-activated K(+) currents in GH(3) lactotrophs

delta-Hexachlorocyclohexane (delta-HCH), a lipophilic neurodepressant agent, has been shown to inhibit neurotransmitter release and stimulate ryanodine-sensitive Ca(2+) channels. However, the effect of delta-HCH on neuronal activity remains unclear, although it may enhance the gamma-aminobutyric acid-induced current. Its effects on ionic currents were investigated in rat pituitary GH(3) cells and human neuroblastoma IMR-32 cells. In GH(3) cells, delta-HCH increased the amplitude of Ca(2+)-activated K(+) current (I(K(Ca))). delta-HCH (100 microM) slightly inhibited the amplitude of voltage-dependent K(+) current. delta-HCH (30 microM) suppressed voltage-dependent L-type Ca(2+) current (I(Ca, L)), whereas gamma-HCH (30 microM) had no effect on I(Ca, L). In the inside-out configuration, delta-HCH applied intracellularly did not change the single channel conductance of large conductance Ca(2+)-activated K(+) (BK(Ca)) channels; however, it did increase the channel activity. The delta-HCH-mediated increase in the channel activity is mainly mediated by its increase in the number of long-lived openings. delta-HCH reversibly increased the activity of BK(Ca) channels in a concentration-dependent manner with an EC(50) value of 20 microM. delta-HCH also caused a left shift in the midpoint for the voltage-dependent opening. In contrast, gamma-HCH (30 microM) suppressed the activity of BK(Ca) channels. Under the current-clamp mode, delta-HCH (30 microM) reduced the firing rate of spontaneous action potentials; however, gamma-HCH (30 microM) increased it. In neuroblastoma IMR-32 cells, delta-HCH also increased the amplitude of I(K(Ca)) and stimulated the activity of intermediate-conductance K(Ca) channels. This study provides evidence that delta-HCH is an opener of K(Ca) channels. The effects of delta-HCH on these channels may partially, if not entirely, be responsible for the underlying cellular mechanisms by which delta-HCH affects neuronal or neuroendocrine function.

Novel effects of propranolol. Release of internal Ca(2+) followed by activation of capacitative Ca(2+) entry in Madin Darby canine kidney cells

The effect of propranolol on Ca(2+) signalling in Madin Darby canine kidney (MDCK) cells was investigated by using fura-2 as a Ca(2+) probe. Propranolol increased cytosolic free Ca(2+) levels ([Ca(2+)](i)) in a concentration-dependent manner between 0.1 and 1 mM. The response was partly inhibited by external Ca(2+) removal. In Ca(2+)-free medium pretreatment with 0.2 mM propranolol partly inhibited the [Ca(2+)](i) rise induced by 1 microM thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+) pump; but pretreatment with thapsigargin abolished propranolol-induced Ca(2+) release. Addition of 3 mM Ca(2+) induced a [Ca(2+)](i) rise after pretreatment with 0.2 mM propranolol in Ca(2+)-free medium. Propranolol (0.2 mM) inhibited 25% of thapsigargin-induced capacitative Ca(2+) entry. Suppression of 1,4,5-trisphosphate (IP(3)) formation by 2 microM U73122, a phospholipase C inhibitor, did not alter 0.2 mM propranolol-induced internal Ca(2+) release. Propranolol (1 mM) also increased [Ca(2+)](i) in human neutrophils. Collectively, we have found that 0.2 mM propranolol increased [Ca(2+)](i) in MDCK cells by releasing Ca(2+) from thapsigargin-sensitive Ca(2+) stores in an IP(3)-independent manner, followed by Ca(2+) influx from external space. Independently, propranolol was able to inhibit thapsigargin-induced capacitative Ca(2+) entry.

Multiplane transesophageal echocardiography for assessing cardiac abnormalities: comparison to biplane imaging

BACKGROUND

Transesophageal echocardiography (TEE) is useful for visualizing the spatial relationships of the cardiac anatomy. The purpose of this study was to compare the diagnostic yield of multiplane TEE with that of biplane TEE in assessing cardiac abnormalities.

METHODS

A total of 102 consecutive patients underwent an initial comprehensive diagnostic assessment using transverse (0 degree) and longitudinal (90 degrees +/- 2 degrees) planes in the biplane imaging technique. "Off-axis" tomographic sections through the full 0 degree to 180 degrees angle were obtained later by means of the gradual electrical rotation of the transducer. The echoscope can be manipulated to improve the quality of images. All data were recorded on high fidelity videotapes. Subsequently, one observer reviewed only biplane TEE images, while another reviewed only multiplane TEE images; both were blinded to the other's TEE data. The echocardiographic results obtained by these two observers were compared to determine whether multiplane TEE provides any additional information.

RESULTS

Multiplane TEE detected more cardiac lesions (275) compared to biplane TEE (235). Significantly more (70 cases) information affecting patient management was obtained using multiplane TEE. Among these patients, biplane TEE detected cardiac lesions in 48 (68.6%) patients. Additional diagnoses provided by multiplane TEE were found in 22 (31.4%) patients. These findings included ventricular septal defect in two patients, prosthetic valve dysfunction in three, cardiac tumor or clot in four, endocarditis in two, aortic dissection in one, valvular abnormality in nine and coronary arteriovenous fistula in one.

CONCLUSIONS

Multiplane TEE provides precise visualization of cardiac structures without undue probe manipulation, resulting in greater diagnostic assurance than does biplane TEE.

Prophylactic banding ligation of high-risk esophageal varices in patients with cirrhosis: a prospective, randomized trial

BACKGROUND/AIMS

Injection sclerotherapy has been used to prevent the first episode of variceal hemorrhage, but the results are controversial. The value of banding ligation in the prophylaxis of the first episode of variceal bleeding has not yet been completely evaluated. This study was conducted to determine whether prophylactic banding ligation is beneficial for cirrhotic patients with high-risk esophageal varices.

METHODS

A total of 127 cirrhotic patients with endoscopically-assessed high-risk esophageal varices but no history of bleeding were randomized to undergo banding ligation (64 patients) or to serve as controls (63 patients). Ligation was performed at 3-week intervals until variceal obliteration was obtained.

RESULTS

During a median follow-up of 29 months, 14 patients (21.8%) in the ligation group and 22 patients (34.9%) in the control group experienced upper gastrointestinal bleeding (p = 0.15). Variceal bleeding occurred in eight patients (12.5%) in the ligation group and 14 patients (22.2%) in the control group (p = 0.22). Blood transfusion requirements were fewer in the EVL group than in the control group (0.6+/-0.4 units vs. 1.2+/-0.8 units, p<0.001). Furthermore, variceal bleeding was significantly reduced in Child-Pugh class B patients treated with ligation compared with the control group (p<0.05). Sixteen patients (25%) in the ligation group and 23 patients (36.5%) in the control group died. Comparison of Kaplan-Meier estimates of time to death for the two groups did not show significant differences (p = 0.19). More patients died of uncontrollable variceal bleeding in the control group (7 patients, 11%) than in the ligation group (3 patients, 4.7%) (p = 0.15).

CONCLUSIONS

Although prophylactic ligation did not significantly reduce the first episode of bleeding from esophageal varices in cirrhotic patients with high-risk esophageal varices, a subgroup of patients (Child-Pugh class B) had a reduced frequency of the first episode of esophageal variceal bleeding after prophylactic banding ligation. Furthermore, there was a trend of reducing mortality from variceal bleeding in patients receiving prophylactic ligation. Prophylactic ligation is a promising treatment, but requires further investigation.

Circadian and weekly variations in pain onset of acute myocardial infarction

BACKGROUND

A seasonal variation with more myocardial infarctions in the winter months due to cold weather has been reported. Other reports have described excess numbers of acute myocardial infarction (AMI) in the summer in Southern USA due to hot temperatures. To determine whether circadian and seasonal variations affect the incidence of AMI in the subtropical area of Taiwan, 480 consecutive patients with AMI admitted to our coronary care units were analyzed.

METHODS

Six-hourly intervals over 24 hours (4 periods), daily intervals in a week (7 days) and monthly intervals in a year (12 months) were respectively studied. The distributions of the numbers of AMI occurring in the six-hour intervals were tested for differences among the four periods using the chi-squared test for goodness of fit.

RESULTS

We found that there was a circadian variation in the onset of AMI with a morning peak (6 am to noon) (35%, chi 2 = 28.52, df = 3, p < 0.01) but no secondary late evening peak. The incidence of AMI was significantly lower on Sundays (9%) than on the other weekdays (chi 2 = 16.37, df = 6, p = 0.012). However, no seasonal variation (no winter or summer peaks) occurred in the incidence of AMI in this study (chi 2 = 0.77, df = 3, p = 0.99).

CONCLUSION

Our results showed that there was a predominant morning peak in the onset of AMI. The low incidence of AMI cases on Sunday compared with other weekdays suggested that relief from tension or workload on Sundays might have an important role in this low percentage of AMI. Differing from other reports, there was no seasonal variation in the occurrence of AMI in our study, suggesting that the warm climate of a subtropical region does not provide an environment that is likely to increase the frequency of AMI.

Intrathoracic extramedullary haematopoiesis complicated by massive haemothorax in alpha-thalassaemia

Intrathoracic extramedullary haematopoiesis (EMH) is a rare entity that is usually asymptomatic. A 44 year old man with alpha-thalassaemia is described who developed dyspnoea and massive left sided haemothorax. The haemoglobin disorder was established by Hgb H staining and haemoglobin electrophoretic studies. The DNA analysis revealed it to be a case of double heterozygous terminal codon mutation with the genotype alphaalphaCS/alphaalphaT. Computed tomographic scanning and magnetic resonance imaging of the thorax showed multiple paravertebral masses which were found by thoracoscopic biopsy to be extramedullary haematopoiesis. Although no additional sclerosing pleurodesis or low dose radiation therapy was given, the lung expanded well and there has been no recurrence of haemothorax to date.