Evidence for microRNA-mediated regulation in rheumatic diseases

MicroRNA (miRNA), a group of short non-coding RNA of approximately 20-22 nucleotides modulating the stability and translational efficiency of target messenger RNA, present an important new layer controlling gene expression. Hundreds to a thousand miRNA have been identified and are predicted to regulate at least one-third of protein-coding transcripts in the mammalian genome. This study reviews the recent advances reinforcing the awareness that miRNA are key players in rheumatic diseases by regulating major pathogenic molecules, such as tumour necrosis factor, central signal pathways, such as type I interferon pathway and critical immunoregulatory cells, such as regulatory T cells. In animals, blockade of miRNA maturation by the deletion of Dicer or Drasha, interference with miRNA function by the mutation of Roquin and the altered expression of individual miRNA (miR-146a) or miRNA cluster (miR-17-92) all lead to the development of autoimmune diseases. Growing evidence also reveals the differential expression of certain immunity-regulating miRNA in rheumatoid patients. The features of miRNA-mediated regulation, the direction of future miRNA study in rheumatic diseases and the application of miRNA in diagnosis, therapy and prognosis will also be briefly discussed.

Antihypertensive action and blockade of alpha1-adrenoceptors by DL-017, a quinazoline derivative

3-[[4-(2-Methoxyphenyl)piperazin-1-yl]methyl]-5-(methylthio)-2,3-dihydroimidazo[1,2-c]quinazoline (DL-017), a quinazoline derivative, exhibits alpha 1 -adrenoceptor antagonistic and type I antiarrhythmic effects on mammalian cardiac tissues. In the current study, the effects of DL-017 on the hemodynamic profile in anesthetized, spontaneously hypertensive rats were evaluated. Intravenous administration of DL-017 induced dose-dependent reductions of heart rate and blood pressure, which persisted over 2 h. DL-017 exerted a maximal antihypertensive effect at 0.1 mg/kg, which was similar to that of 0.1 mg/kg of prazosin. DL-017 was able to block the pressor response to phenylephrine but not to angiotensin II. Regional cerebral blood flow of the right parietal cortex decreased by 14 +/- 4% 10 min after bolus injection and then rapidly returned to control levels while the arterial pressure was still low. These results indicate that blockade of the alpha 1 -adrenoceptor by DL-017 contributes to reduction of arterial pressure. The antihypertensive effect without reflex tachycardia and loss of autoregulation of cerebral blood flow makes DL-017 suitable for chronic long-term treatment of hypertension.

Blockade of alpha1-adrenoceptors and cardiac depressant effect by a newly synthetic antihypertensive drug, DL-017 of quinazoline derivative

The electromechanical effects of 3-[[4-(2-methoxy phenyl)piperazin-1-yl]methyl]-5-(methylthio)-2,3-dihydroimidazo[1,2-c]quinazoline (DL-017), a newly synthesized quinazoline-derived antihypertensive agent, on mammalian cardiac tissues were evaluated. In driven canine Purkinje fibers, DL-017 decreased twitch tension, the maximal rate of upstroke of the action potential (Vmax), and intracellular Na+ activity (a(i)Na) in a concentration-dependent manner. The action potential duration was decreased in canine Purkinje fibers but increased in guinea pig papillary muscles. In guinea pig ventricular papillary muscles, phenylephrine in the presence of 1 microM propranolol increased the twitch tension in a concentration-dependent manner. At 10 microM, phenylephrine significantly decreased a(i)Na and shortened the action potential duration. DL-017 at 0.01 microM inhibited these phenylephrine-induced effects and shifted the concentration-dependent curve to the right. In sinoatrial nodes, DL-017 inhibited pacemaker activity, involving decreases in the slope of diastolic depolarization and Vmax and an increase in a delay of repolarization. These results suggest that, in addition to blockade of alpha1-adrenoceptors and Na+ channels, DL-017 reduces cardiac excitability and contractility in association with inhibition of slow inward Ca2+ and outward K+ channels. Since two order higher concentrations are required, the contribution of DL-017 to cardiac depressant from blockade of ionic channels seems to be less important when this compound is clinically used as an antihypertensive drug.

Emergency medical technicians' disaster training by tabletop exercise

The objective of this study was to assess the attitudes of emergency medical technicians (EMTs) toward tabletop drills to determine the effect of tabletop simulation on the EMT student perception of disaster preparedness and management. In November 1998 and April 1999, 59 firefighters underwent 260 hours of EMT intermediate level training at the National Cheng Kung University Hospital in Tainan, Taiwan. All participants had experience in field disaster exercise training before they attended this EMT training course. The EMT courses included a disaster and mass-casuality incident program. A 9-item questionnaire was completed by the 59 EMTs before (for field exercise) and after undergoing the tabletop drills. The results of the survey revealed that the field operation exercise could not provide adequate provisions to link the results of disaster exercises to appropriate changes in terms of training, equipment, supplies, and plans. Field operation failed to show the ability of others to fill in during the absence of key officials. Tabletop drilling provided better performance for these 2 issues. Tabletop exercise also provided a better chance than field exercise to evaluate the response without the use of telephones, which are not always reliable in real emergency situation. For disaster exercises, limitations of field operation drills such as communications, coordination, assignment of responsibilities, and postevent mitigation priorities were noted, and tabletop drills provided additional benefits for these settings. Large-scale effect evaluation of different drills may be necessary to design future disaster preparedness programs.

Characteristics of repeated ambulance use in an urban emergency medical service system

BACKGROUND AND PURPOSE

Although many studies have examined the reasons for repeated use of emergency medical service (EMS), little information is available concerning repeated ambulance use in Taiwan. This study evaluated the characteristics of repeated EMS ambulance use in an urban EMS system in Taiwan.

METHODS

Data from a local EMS computerized database for the period from January 1996 through December 1998 were collected for analysis. All calls to the dispatch center that resulted in EMS transports were included. Repeat users were identified by matching the user name, sex, age, and home address. Transports were categorized according to how many times the patient was transported by ambulance during the 3-year period: single use, one time; repeated use, two or three times; or frequent use, more than three times.

RESULTS

During the 36-month study period, there were 41,792 calls, with 13,076 non-transports (a non-transport rate of 31.3%). Of the 28,716 transports during the study period, 2,101 represented repeated or frequent use (7.3%); the rate of frequent use was 1.4% (406/28,716). The frequency of repeated use reached a daily first peak at 8:00 AM, with the second and third peaks at 1:00 PM and 7:00 PM. The mean age increased with increasing repeated use of transport (37.25 +/- 0.24 vs 41.55 +/- 1.03 vs 46.23 +/- 1.57 years, respectively; p < 0.001). The percentage of non-trauma missions increased with increasing repeated use of transport (26.3% vs 55.6% vs 73.2%; p < 0.001). Response time significantly increased for repeated use (analysis of variance [ANOVA], p < 0.001). The on-scene interval (time from arrival until departure) in the single-use group was shorter than in the repeated and frequent use groups (ANOVA, p < 0.005).

CONCLUSIONS

The results of this study indicate that the characteristics of repeat users of EMS transport differ from those of single users. Characteristics of service time, reason for transport, and interval to each subsequent call varied among different groups of users. Studies of repeat use under a wider range of conditions such as in rural EMS systems and after implementation of a priority-dispatch system are needed to determine the implications of repeated ambulance use.

Sick sinus syndrome in a patient with single coronary artery anomaly

Single coronary artery anomaly is very rare. The reported manifestations include angina pectoris and congestive heart failure. Here we describe a case of single coronary artery anomaly presenting as sick sinus syndrome, which has no literature precedence. A 47-year-old woman had complained of intermittent dizziness for years. A Holter electrocardiogram showed sinus bradycardia and junctional or ventricular rhythm with a maximal ventricular pause of up to 3.2 seconds. Electrophysiologic study revealed prolonged corrected sinus nodal recovery time. Coronary angiography showed that the left anterior descending artery had a long course with a side branch originating from the proximal part and coursing anteriorly to the territory of the proximal portion of the right coronary artery. The sinus node is usually supplied by the sinoatrial branch via the right coronary artery. Aortography showed that the right coronary artery ostium was absent. A permanent pacemaker was implanted and the patient was discharged in good condition. The present case suggests that coronary artery anomaly may lead to compromised blood supply to the sinus node, and hence sick sinus syndrome.

Sodium nitroprusside increases pacemaker rhythm of sinoatrial nodes via nitric oxide-cGMP pathway

Effects of sodium nitroprusside (SNP), a nitric oxide donor, on the action potential in isolated guinea-pig sinoatrial nodes and ventricular papillary muscles were investigated. In the driven ventricular papillary muscle, SNP (10(-10)-10(-3) M) decreased the twitch tension in a concentration-dependent manner without significantly changing the configuration of action potential and the maximal velocity of depolarizing upstroke. In isolated sinoatrial nodes, SNP (10(-8)-10(-3) M) increased the pacemaker rhythm in a concentration-dependent manner. At 10(-5) M SNP, the pacemaker activity increased from 197.2+/-6.1 to 221.4+/-9.7 bpm. Changes of configuration of the action potential included a decrease of the duration of repolarization, i.e., from peak to the maximal diastolic potential (MDP), from 141.4+/-6.4 to 130.0+/-7.0 ms and an increase of the slope of the diastolic membrane potential from 101.6+/-5.3 to 116.5+/-7.3 mV/s (n=6, p<0.05). However, MDP and threshold potential were not significantly changed. Methylene blue (MB, 10(-5) M), a guanylate cyclase inhibitor, significantly decreased the pacemaker activity of the sinoatrial node by increasing the durations of repolarization and diastolic depolarization. After pretreatment with 10(-5) M MB, the effect of SNP was inhibited. The results indicate that nitric oxide, released from SNP, increases the pacemaker activity by enhancing the rates of repolarization and diastolic depolarization. These effects are possibly due to increases in delayed-rectifier K+ and diastolic slow inward currents, which are involved in a mechanism associated with the NO-cGMP pathway.

Clinical presentations and prognostic factors of a glyphosate-surfactant herbicide intoxication: a review of 131 cases

OBJECTIVE

Suicide attempts with agricultural chemicals are common in southern Taiwan. Among them, glyphosate-surfactant herbicide (GlySH) intoxication has been encountered with increasing frequency. Although a number of reports have described the clinical course and outcomes following ingestion, predictors of serious complications and mortality have not been elucidated. The purpose of this study was to define predictors of serious complications and probable mortality.

METHODS

This was a retrospective study of 131 GlySH-intoxicated patients treated at the National Cheng Kung University Hospital from 1988 to 1995. Medical charts were reviewed and clinical and laboratory variables were abstracted, looking for predictors of mortality.

RESULTS

The most common symptoms included sore throat (79.5%), and nausea with or without vomiting (73.8%). The most common laboratory findings were leukocytosis (68.0%), low serum bicarbonate (48.1%), and acidosis (35.8%). Overall, 11 of 131 patients (8.4%) died; the mean +/- SEM time to death was 2.8 +/- 0.8 days after presentation. When comparing the clinical and laboratory characteristics among the survivor and fatality groups, significant differences were identified. Respiratory distress, pulmonary edema, respiratory distress necessitating intubation, shock (systolic blood pressure less than 90 mm Hg), altered consciousness, abnormal chest x-ray, renal failure necessitating hemodialysis, larger amount of ingestion (>200 mL), and hyperkalemia were predictors highly associated with poor outcomes and mortality. Using multiple logistic regression, three predictors were identified, which may predict mortality in severely intoxicated patients.

CONCLUSIONS

In managing patients who have larger amount of GlySH ingestion, airway protection, early detection of pulmonary edema, and prevention of further pulmonary damage and renal damage appear to be of critical importance.

Effect of atrial fibrillation on pulmonary venous flow patterns assessed by Doppler transesophageal echocardiography

STUDY OBJECTIVES

To investigate the effect of atrial fibrillation (AF) on pulmonary venous flow (PVF) patterns in a cohort with nonrheumatic AF.

DESIGN AND SETTINGS

A prospective and controlled study undertaken at a tertiary referral medical center.

PATIENTS AND MEASUREMENTS

The echocardiographic parameters of left superior PVF as assessed by Doppler transesophageal echocardiography in 40 patients with chronic AF (group 1) were compared to those of 33 volunteers with sinus rhythm (group 2) and well-matched baseline characteristics.

RESULTS

: All group 1 patients presented with single systolic forward flow (SFF) patterns. In contrast, single and double SFF patterns were found equally in group 2. With regard to reverse flow (RF), most group 1 patients (33 of 40) had an early systolic RF and none had atrial RF; however, most group 2 subjects (29 of 33) had an atrial RF. Some of the group 1 patients (17%) had a late systolic RF in the absence of significant mitral regurgitation. In group 1, the SFF appeared later and disappeared earlier than in group 2. The mean systolic peak velocity and time-velocity integral (TVI) of the SFF were significantly lower in group 1 compared to group 2. The diastolic peak velocity and TVI were not significantly different between groups.

CONCLUSIONS

: Our data indicate that AF independently and significantly affects the PVF and leads to characteristic flow patterns different from sinus rhythm. The presence of AF reduces SFF in addition to the absence of atrial RF. These changes in the flow patterns should be taken into account while interpreting the implications of PVF in the presence of AF.

Association of follow-up change of left atrial appendage blood flow velocity with spontaneous echo contrast in nonrheumatic atrial fibrillation

STUDY OBJECTIVES

To evaluate the time-related change of left atrial (LA) appendage flow velocity in chronic atrial fibrillation (AF) by follow-up transesophageal echocardiography (TEE) and to investigate its association with the occurrence of LA spontaneous echo contrast.

DESIGN

Prospective follow-up study.

SETTING

University-based, tertiary referral medical center.

PATIENTS

Forty-seven patients with chronic nonrheumatic AF.

INTERVENTIONS

All studied patients underwent both a baseline and follow-up TEE during a mean period of 13 +/- 7 months.

MEASUREMENTS AND RESULTS

Baseline TEE revealed that LA spontaneous echo contrast was present in 28 patients (group 1) and was absent in 19 patients (group 2). The LA appendage flow velocity profiles at baseline were significantly lower in group 1 than in group 2; on follow-up, the appendage flow velocities decreased significantly in group 2, but were not significantly changed in group 1. Follow-up TEE revealed that spontaneous echo contrast was persistent in all group 1 patients. In group 2, LA spontaneous echo contrast was newly observed in 9 patients (group 2A) but was persistently absent in 10 patients (group 2B). In group 2A, all of the LA appendage flow velocity profiles decreased significantly at the follow-up study. In group 2B, however, only LA appendage inflow velocity integral showed significant decrease on follow-up; there were no significant changes in LA appendage outflow velocity indexes and peak inflow velocity.

CONCLUSIONS

LA appendage flow velocity may decrease with time in some patients with AF, and this change is associated with a new occurrence of LA spontaneous echo contrast. For patients without LA spontaneous echo contrast, serial follow-up of the LA appendage flow velocity profiles may be useful for predicting future development of spontaneous echo contrast. Once LA spontaneous echo contrast occurs in AF patients, it tends to persist with time and the LA appendage is usually under a persistently low flow state.

G-33A mutation in the promoter region of thrombomodulin gene and its association with coronary artery disease and plasma soluble thrombomodulin levels

Thrombomodulin is an endothelial glycoprotein that decreases thrombin activity and activates protein C. A recent study has shown that G-33A promoter mutation of the thrombomodulin gene occurs particularly in Asians. In this study, we analyzed the distribution of G-33A mutation in the promoter region of the thrombomodulin gene in the Chinese population and determined whether the mutation might be a risk for coronary artery disease (CAD). In addition, the influence of this mutation on plasma soluble thrombomodulin levels in patients with CAD was also examined. We studied 320 consecutive patients (mean age 63 years; 73% men) with CAD and 200 age- and sex-matched control subjects. Screening for thrombomodulin G-33A promoter mutation was conducted using polymerase chain reaction, single-strand conformation polymorphism, and direct deoxyribonucleic acid sequencing. The frequency of the G-33A mutation (GA+AA genotypes) was significantly higher in the CAD group (23.8% vs 15.5%, odds ratio [OR] 1.70, p = 0.031). Multiple logistic regression analysis showed that the mutation was an independent risk factor (OR 1.81, p = 0.016) for CAD, as was hypertension (OR 1.44, p = 0.040), diabetes mellitus (OR 2.50, p <0.001), and smoking (OR 2.15, p <0.001). In CAD patients with GG genotype, the soluble thrombomodulin level increased with the extent of CAD (36 +/- 15 vs 47 +/- 18 vs 55 +/- 36 ng/ml in 1-, 2-, or 3-vessel CAD, p <0.001). However, in CAD patients with G-33A mutation, there was no difference between the levels of soluble thrombomodulin (39 +/- 17 vs 37 +/- 15 vs 42 +/- 18 ng/ml, p = NS) in 1-, 2-, or 3-vessel CAD. Our observations suggest that there is a significant association of the G-33A mutation in thrombomodulin gene with CAD, and this mutation may influence the soluble thrombomodulin levels in patients with CAD.

Correlation of homocytsteine levels with the extent of coronary atherosclerosis in patients with low cardiovascular risk profiles

Elevation of homocysteine is now known as an independent risk factor for vascular diseases. However, influences of homocysteine to the extent of coronary atherosclerosis in patients with different coronary risk profiles have not been studied. In this study, we used angiographic "diffuse score" and "clinical vessel score" to evaluate the extent of coronary atherosclerosis, and examined the correlation between levels of serum total homocysteine and angiographic scores among patients with high- and low-risk profiles. Seventy consecutive patients (58 men and 12 women, mean age 50 years) undergoing selective coronary angiography for the first time were recruited for this study. Patients were divided into high-risk (risk factor > or =3, n = 35) and low-risk (risk factor <3, n = 35) groups. Linear regression analysis revealed that levels of serum homocysteine were only significantly correlated with diffuse (r = 0.217, p = 0.007) and clinical vessel (r = 0.078, p = 0.037) scores in low-risk patients. These correlations could not be observed in diffuse (r = 0.070, p = 0.319) and clinical vessel (r = -0.001, p = 0.970) scores in the high-risk group. In conclusion, levels of homocysteine correlated with the extent of coronary atherosclerosis only among patients with low cardiovascular risk profiles.

Pulmonary artery leiomyosarcoma

Pulmonary artery leiomyosarcoma is a rare but highly lethal disease, and can be mistaken for pulmonary thromboembolism. We report a case of pulmonary artery leiomyosarcoma managed with surgical resection, chemotherapy, and radiotherapy. A 57-year-old woman was admitted with complaints of aggravated dyspnea. She was initially treated with oxygen therapy and heparinization for a suspected pulmonary embolism. Echocardiography revealed a dilated right atrium and ventricle and severe tricuspid regurgitation, with an estimated systolic right ventricular pressure of 95 mm Hg; a shadow of a mass in the main pulmonary artery was also noted. Right ventriculography revealed a filling defect, and to-and-fro motion of the mass in the main pulmonary artery. The left pulmonary artery was almost totally occluded by the mass. The patient's condition improved dramatically after palliative excision of the mass and patch reconstruction of the outflow tract of the right ventricle with a bicuspid xenograft. Pathologic examination of the mass revealed leiomyosarcoma. Chemotherapy and radiotherapy were subsequently administered and follow-up imaging studies 3 months postoperatively revealed no recurrence of the tumor. The patient remains well, more than 1 year after treatment. This report emphasises that pulmonary artery sarcoma should be considered in the differential diagnosis in cases of suspected pulmonary thromboembolism.

Prognostic determinants of infective endocarditis in the 1990s

The clinical profiles of infective endocarditis (IE) might have changed in recent years, owing to the advent of transesophageal echocardiography, the introduction of new diagnostic criteria, and the increased frequency of intravenous drug abuse. In this retrospective study, we sought to identify factors affecting the in-hospital outcome of IE patients in a single tertiary referral center in the 1990s (1990-1997). Eighty-eight episodes of IE in 80 consecutive patients admitted from January 1990 through June 1997 were evaluated. Clinical variables that were significantly associated with in-hospital mortality in univariate analyses were entered into a multiple logistic regression model. A total of 22 patients (25%) died. Fatal episodes were significantly more likely than non-fatal episodes to involve older patients (> or = 50 years), use of coumadin, short interval between symptom onset and hospitalization (< 15 days), noncardiac shock, and complications of the heart, central nervous system, and kidneys. White blood cell counts and C-reactive protein concentrations were also significantly higher in fatal than in non-fatal episodes of IE. Multivariate analysis showed that in-hospital mortality was associated with noncardiac shock, neurological complications, cardiac complications, and older age (> or = 50 years). Compared with previous reports, our findings suggest that the clinical profiles of IE have undergone some changes in the 1990s. The most important prognostic predictors of in-hospital mortality in patients with IE were noncardiac shock and neurologic complications.

Prognostic significance of elevated hemostatic markers in patients with acute myocardial infarction

OBJECTIVES

The purpose of this study was to determine whether the elevated levels of hemostatic markers in the early phase of myocardial infarction may serve as risk factors for subsequent cardiac mortality.

BACKGROUND

Increased plasma hemostatic markers were noted in acute myocardial infarction, indicating that the blood coagulation system is highly activated in those patients. However, there are few clinical data concerning the association between the elevated hemostatic markers and survival in patients with myocardial infarction.

METHODS

Blood samples were obtained from 64 patients (mean age 67 +/- 11 years; 49 male) with acute myocardial infarction within 12 h after the onset of symptoms and before the initiation of any antithrombotic treatment. We measured plasma concentrations of fibrinopeptide A (FPA), prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) using the enzyme-linked immunosorbent assay method, and examined the associations between the level of these markers and survival with Cox proportional hazards models.

RESULTS

The follow-up time was 27 +/- 17 months, and 19 patients died of cardiac causes during the follow-up. Univariate survival analysis identified Killip class IV (hazard ratio 4.86; 95% confidence interval [CI] 1.55-15.19), left ventricular ejection fraction (hazard ratio 0.94; 95% CI 0.90-0.99), FPA (hazard ratio 1.54; 95% CI 1.13-2.10), F1+2 (hazard ratio 2.03; 95% CI 1.17-3.53) and TAT (hazard ratio 1.88; 95% CI 1.27-2.79) as significant factors associated with cardiac mortality. In multivariate analyses, only FPA level (hazard ratio 1.84; 95% CI 1.03-3.30) and left ventricular ejection fraction (hazard ratio 0.93; 95% CI 0.88-0.98) were independent predictors of cardiac mortality.

CONCLUSIONS

Elevated FPA in the early phase of myocardial infarction identifies patients with increased risk for subsequent cardiac death. This association appears to be independent of residual left ventricular function after infarction.

Prognostic value of Doppler-derived mitral deceleration time in postinfarction patients with left ventricular ejection fractions of 35% or more

Short Doppler-derived mitral deceleration time of early filling has been proved to be an independent predictor of poor prognosis in patients with left ventricular dysfunction. However, the prognostic value of Doppler-derived mitral deceleration time in postinfarction patients without overt left ventricular dysfunction is poorly understood. A total of 27 survivors of acute myocardial infarction with left ventricular ejection fractions of 35% or more, as determined by radionuclide ventriculography, were prospectively studied. Doppler study was performed 5 to 7 days after the index infarction. The patients were divided into two groups. Group A included 10 patients whose mitral deceleration time was 125 msec or less and group B consisted of 17 patients whose mitral deceleration time was 125 msec or more. The two groups were similar in terms of age and gender distribution and there were no statistically significant differences in coronary risk factors, peak creatine kinase concentration, location of infarction, Killip classification, thrombolytic therapy, left ventricular ejection fraction, or medications. After a mean follow-up period of 30 months, the rate of congestive heart failure (New York Heart Association, NYHA, class II or above) was significantly higher in group A (5/10) than in group B (1/17) (p < 0.01). These results suggest that a short mitral deceleration time could be a useful early predictor of the potential development of future congestive heart failure in postinfarction patients with left ventricular ejection fractions of 35% or more.

Decreased left atrial appendage function is an important predictor of elevated left ventricular filling pressure in patients with congestive heart failure

OBJECTIVE

The aim of this study was to investigate whether left atrial (LA) appendage function, as indicated by LA appendage blood flow velocities and its ejection fraction, could identify elevated left ventricular filling pressure in patients with chronic congestive heart failure.

METHODS

Using transesophageal echocardiography, adequate pulsed Doppler LA appendage active emptying and filling velocities could be recorded in 25 consecutive patients (16 men and 9 women, aged 57+/-10 years) with chronic congestive heart failure (symptom duration > or =1 year). LA appendage ejection fraction calculated as (LA appendage maximal area)-(LA appendage minimal area)/(LA appendage maximal area) x 100 was also determined in these patients. Left ventricular end-diastolic pressure was recorded during cardiac catheterization performed within 24 h of echocardiographic study.

RESULTS

Left ventricular end-diastolic pressure was 2 to 47 mm Hg. There were close negative correlations of LA appendage emptying velocity (r=-0.508; P<0.01), filling velocity (r=-0.429; P<0.05) and LA appendage ejection fraction (r=-0.523; P<0.005) with left ventricular end-diastolic pressure. LA appendage active emptying velocity <30 cm/s predicted left ventricular end-diastolic pressure >25 mm Hg with a sensitivity of 72.7%, a specificity of 92.9% and a positive and negative predictive value of 88.9 and 81.3%.

CONCLUSIONS

The findings suggest that measurement of LA appendage blood flow velocities and contractile function by transesophageal echocardiography can be used to predict elevated left ventricular filling pressure in patients with congestive heart failure.

The involvement of nitric oxide in synergistic neuronal damage induced by beta-amyloid peptide and glutamate in primary rat cortical neurons

Abnormal extracellular accumulation of beta-amyloid (Abeta), the major component of senile plaques in the Alzheimer's brain and the excitatory amino acid glutamate are both considered to be associated with neurodegeneration. We studied whether nitric oxide (NO) was involved in neuronal damage induced by Abeta and glutamate in primary rat cortical neurons. Our results demonstrated that (1) Both neuronal damage and NO production were synergistically induced by Abeta-(25-35) and glutamate; (2) This synergistic neuronal damage induced by Abeta-(25-35) and glutamate was attenuated by selective inhibitors of NO synthase. We propose that cytotoxic characteristics of NO, at least in part, are involved in the synergistic neuronal damage induced by Abeta and glutamate, presumably seen in Alzheimer's brains.

Successful delayed thrombolytic therapy in a patient with massive pulmonary embolism

Pulmonary embolism can be a catastrophic event leading to early death or serious hemodynamic instability. Thrombolytic therapy, in addition to heparin therapy, may improve the clinical condition and reduce the chance of recurrent pulmonary embolism in some cases. However, the acceptable "time window" for thrombolytic therapy is not well documented, though it has been used successfully as late as 14 days after pulmonary embolism. Successful delayed thrombolytic therapy beyond this "time window" in patients with massive pulmonary embolism has not been reported. We report a case of massive pulmonary embolism in which thrombolytic therapy was delayed more than 1 month after symptom onset. A 56-year-old woman was taken to National Cheng Kung University Hospital because of an episode of recurrent syncope, followed by progressive shortness of breath of 1 month's duration. Hypoxemia and hemodynamic instability were noted on admission. Echocardiography and a lung perfusion scan provided strong evidence of pulmonary embolism. Subsequent pulmonary angiography confirmed the diagnosis of multiple pulmonary emboli. The patient received a standard dose of intravenous tissue plasminogen activator 7 days after admission because of persistent symptoms and hypoxemia. Her clinical condition dramatically improved after treatment. Follow-up imaging studies showed resolution of the emboli. She was discharged in good condition. This case suggests that delayed thrombolytic therapy in patients with massive pulmonary embolism can still be beneficial in selected cases, even if given more than 2 weeks after symptom onset.

Effects of spontaneous respiration on transmitral Doppler flow patterns in normal subjects and patients with coronary artery disease

BACKGROUND

The potential effects of spontaneous respiration on Doppler mitral inflow patterns in patients with abnormal left ventricular diastolic function are poorly understood.

METHODS AND RESULTS

The respiratory changes of Doppler transmitral flow velocity indexes were investigated in 20 healthy subjects and 20 patients with coronary artery disease. All patients had a mitral inflow pattern of abnormal left ventricular relaxation (reversal of early/late diastolic peak flow velocity ratio). The Doppler mitral inflow signals were measured at end-expiration and end-inspiration. In both groups, the early diastolic peak flow velocity and flow velocity integral, the ratio of early/late diastolic peak flow velocity, and the ratio of early/late diastolic flow velocity integral at end-inspiration were significantly lower than those at end-expiration. However, the late diastolic peak flow velocity and flow velocity integral were not significantly different between end-inspiration and end-expiration. During inspiration, the early diastolic peak flow velocity and the ratio of early/late diastolic peak flow velocity were reduced by an average of 23% and 22%, respectively, in normal subjects and were reduced by an average of 19% and 17%, respectively, in the patient group.

CONCLUSIONS

Left ventricular early diastolic filling can be substantially reduced by inspiration in normal subjects and in patients with abnormal left ventricular diastolic function. The potential effects of respiratory cycle should be taken into account when assessing left ventricular diastolic function by using Doppler echocardiography.

Vascular expression of heat shock protein 72 in fructose-induced hypertensive rats

Heat shock proteins (HSPs) have been implicated in protecting the cardiovascular system and in the pathogenesis of hypertension in stressed animals. In the present study, we used a fructose-induced hypertension model to explore the vascular expression of HSP72, the major inducible heat shock protein, in response to stress. Normal Sprague-Dawley rats gradually developed hypertension about 2 weeks after feeding with fructose-enriched diet and the elevated blood pressure became stable 5 weeks following diet treatment. The in vivo expression of HSP72 was absent in control rats but was transiently induced in the aorta of fructose-fed rats during the development of hypertension. Aortic HSP72 was undetectable at the established phase of hypertension. The expression of HSP72 in responses to heat shock, or vasoactive agents were examined in cultured aortic smooth muscle cells. Heat shock induced the expression of HSP72 in cells from fructose-fed rats and age-matched control rats, and the expression levels were generally not significantly varied at different sampling time points in either cell source. Also, there was no apparent difference in the magnitude of HSP72 expression between two cell sources at each selected time point. Norepinephrine or angiotensin II induced a similar level of HSP72 expression in either cell source regardless of sampling time point. These data suggest that HSP72 is associated with the development of hypertension in this model and may exert protective effect on the vasculature in response to hemodynamic stress during the early stage of hypertension.

Relation of left atrial spontaneous echo contrast with prethrombotic state in atrial fibrillation associated with systemic hypertension, idiopathic dilated cardiomyopathy, or no identifiable cause (lone)

To investigate the association of left atrial (LA) spontaneous echo contrast with the hemostatic state in nonrheumatic atrial fibrillation (AF), we examined the plasma levels of prothrombin fragment 1+2 and fibrinopeptide A in 73 patients with chronic nonrheumatic AF undergoing transesophageal echocardiography and 38 age-matched normal subjects. The results support the theory that LA spontaneous echo contrast in nonrheumatic AF is associated with a hypercoagulable state, especially in patients with marked LA spontaneous echo contrast.

Amebic liver abscess complicated with cardiac tamponade and mediastinal abscess

Amebic pericarditis is an extremely rare complication of liver abscess and an uncommon etiology of sterile pericardial effusion with cardiac tamponade. The association of mediastinal abscess in this clinical setting has not been reported in the literature. Herein, we describe a case of amebic liver abscess complicated with mediastinal abscess and amebic pericarditis with cardiac tamponade. A 44-year-old man was admitted to our hospital because of shortness of breath for the previous 2 days. Cardiac tamponade was diagnosed and emergency pericardiectomy was performed. Chocolate-like pus was found in the pericardial sac and mediastinal space during surgery. Abdominal computed tomography revealed an ill-defined hypodense lesion over the left lobe of the liver, suggesting a liver abscess. Amebic liver abscess and pericarditis were diagnosed on the basis of a high serum titer of amebic antibodies on hemagglutination test. The patient was treated with metronidazole for 2 weeks and discharged in good condition. This case should alert clinicians to the possibility of amebic pericarditis in patients with cardiac tamponade associated with chocolate-like sterile pus in the pericardium and mediastinum. To establish the diagnosis of amebic pericarditis, one should investigate the presence of a liver abscess, a high serum titer of amebic hemagglutination antibodies, and the presence of Entamoeba histolytica trophozoites in the pericardium or pericardial aspirate.

Venous access thrombosis detected by transcutaneous vascular ultrasound in patients with single-polyurethane-lead permanent pacemaker

In order to assess the incidence of significant venous thrombosis after transvenous permanent pacemaker implantation, transcutaneous ultrasound studies were performed in 109 consecutive patients with single-polyurethane-lead pacemakers. Ultrasonic evaluation was found to be a good noninvasive method in assessing the veins. Six patients (5.5%) were found to have significant venous obstruction in the subclavian vein. However, none of them were symptomatic. No difference in the incidence of venous obstruction was found, based on the age, duration of implantation, operative technique, potentially thrombogenic factors including atrial fibrillation, diabeties mellitus, hypertension, heart failure and end-stage renal disease.

Elevation of soluble adhesion molecules is associated with the severity of myocardial damage in acute myocardial infarction

In 20 patients with acute myocardial infarction, blood samples were taken to study the serial changes in the soluble intercellular adhesion molecule-1 (ICAM-1), vascular cellular adhesion molecule-1 (VCAM-1) and E-selectin. Results indicated that soluble ICAM-1 increased significantly and persisted throughout the study period; however, soluble E-selectin was significantly elevated only transiently and decreased rapidly thereafter, and the VCAM-1 did not increase during entire study period. There was a significant correlation between the levels of ICAM-1, E-selectin 6 hours after admission, and peak creatine kinase level; the levels of ICAM-1 and E-selectin were also positively correlated with total leukocyte count at admission.

Natural history of left atrial spontaneous echo contrast in nonrheumatic atrial fibrillation

A prospective study was designed to investigate potential changes of left atrial (LA) spontaneous echo contrast with time and the effects of antithrombotic therapy on its presence in 77 patients with chronic nonrheumatic atrial fibrillation (AF), using serial transesophageal echocardiography (TEE). During a mean follow-up period of 20 +/- 15 months (range 6 to 77), a total of 197 TEE studies were performed in these patients. Baseline TEE revealed that LA spontaneous echo contrast was absent in 43 patients (group 1) and present in 34 (group 2). LA thrombus was found in 8 of group 2 but in none of the group 1 patients. During the follow-up period, only 2 of the group 1 patients were receiving antithrombotic agents; the patients in group 2 without LA thrombus were treated with either warfarin or aspirin, whereas those with LA thrombus were treated with warfarin. On the latest TEE study, LA spontaneous echo contrast was observed in 19 of the group 1 patients (44%) and was persistently found in all of the group 2 patients. During the study period, no patient was found to develop new LA thrombus formation and only 4 episodes of transient ischemic attack were recorded in 4 patients (embolic event rate = 3.1% per year). Of these, 2 were observed in group 1 and the remaining 2 were from group 2 and under aspirin therapy (event rate = 2.2% and 4.7% per year, respectively). In the subgroup of patients with LA thrombus receiving warfarin therapy, follow-up TEE revealed complete resolution of the thrombi in 6 and partial resolution in the remaining 2 in spite of the persistence of LA spontaneous echo contrast; none of these patients developed clinical thromboembolic events during the study period. Thus, future occurrence of LA spontaneous echo contrast could be observed by serial TEE at a substantial rate in patients with nonrheumatic AF who have no LA spontaneous echo contrast; follow-up TEE should be recommended for these patients to detect early the potential occurrence of LA spontaneous echo contrast if preventive antithrombotic therapy is not considered. Although warfarin therapy is associated with resolution of LA thrombus, neither warfarin nor aspirin is effective for suppressing the presence of LA spontaneous echo contrast in nonrheumatic AF.

Thrombolytic therapy for mitral valve thrombosis

A 44-year-old man with a St. Jude mitral valve was admitted because of progressive pulmonary edema. He was diagnosed with prosthetic heart valve thrombosis (PHVT) based on the findings of "muffled" prosthetic valve clicks. Doppler echocardiographic evidence of severe mitral stenosis and transesophageal echocardiographic evidence of limited mitral valve motility. Because the patient hesitated to undergo our recommended surgical treatment, he was immediately treated with intravenous recombinant tissue plasminogen activator (100 mg over 3 h) followed by heparinization. Two hours after the thrombolytic therapy, the prosthetic valve clicks became clearly audible and his congestive symptoms were dramatically improved. Follow-up echocardiography no longer-showed significant mitral valve obstruction. A transient cerebral ischemic attack occurred at the end of thrombolytic therapy but there were no neurologic sequalae. The patient, on warfarin therapy, was well at follow-up 8 months after discharge. Surgical intervention has long been the standard therapy for patients with PHVT. Our case experience suggests that thrombolytic therapy may be considered as an effective alternative to surgical intervention for selected patients with PHVT. In this report, we also review the current literature regarding the indications, effectiveness and safety of thrombolytic therapy in PHVT.

Computerized quantification analysis of left ventricular wall motion from echocardiograms

Two-dimensional echocardiography (2-D echo) imaging is a more attractive clinical tool than other modalities that either involve radiation exposure or are too slow to image heart motion in real-time. Computer-aided analysis of left ventricular(LV) wall motion provides quantitative parameters for diagnosis. This study presents a computerized model for quantitative analysis of left ventricular wall motion from two-dimensional echocardiography by the application of image processing algorithms, including automatic threshold estimation, contrast stretching, boundary detection and border smoothing. The wall motion measurements rely primarily on sequential changes from end-diastolic to end-systolic frames in the left ventricular contours of apical four-chamber view echocardiograms. Left ventricular wall motion was analyzed on the 30 segments of 5 patients with acute myocardial infarction. The results from the computerized model were compared to those obtained from qualitative analysis of echocardiograms by an experienced clinical cardiologist who was unaware of the results of quantitative data.

Application of automatic boundary detection for computerized quantitative analysis of left ventricular regional wall motion by two-dimensional echocardiography

This study was designed to set up a computer-aided image processing algorithm for boundary detection from two-dimensional echocardiography and to establish a computerized model for quantitative analysis of left ventricular wall motion with the application of automatic boundary detection. The four-chamber view echocardiographic images of seven normal subjects and five patients with acute myocardial infarction were investigated. The main steps of image processing in this algorithm included automatic threshold estimation, contrast stretching, radial search of endocardial boundary, and smoothing of the boundary. The displacements of the left ventricular endocardial contour from end-diastolic to end-systolic frame were measured using a sample point connection model. For analysis of the regional contraction, the left ventricular endocardial contour was divided equally into six segments. The wall motion curves in patients were compared with the normal wall motion pattern established from the normal subjects to identify the segments with normal or abnormal wall motion. The results of this quantitative method were compared with those of qualitative analysis. In the 30 segments of the five patients, quantitative analysis correctly identified nine of the 11 segments with abnormal wall motion diagnosed by qualitative analysis (sensitivity, 82%) and identified 17 of the 19 segments with normal wall motion (specificity, 89%). The positive and negative predictive values of quantitative analysis were 82% (9 of 11) and 89% (17 of 19), respectively, and the diagnostic accuracy was 87% (26 of 30). Our preliminary results suggest that computer-aided boundary detection can be applied to establish an objective and useful model for quantitative analysis of left ventricular regional wall motion.

Combined use of astemizole and ketoconazole resulting in torsade de pointes

Torsade de pointes is a serious ventricular arrhythmia which is usually associated with a long QT interval. It is important to recognize the possible predisposing factors for the management of this arrhythmia. Prolongation of the QT interval and torsade de pointes has been reported in patients with an overdose of astemizole. We report on a 63-year-old woman presenting with torsade de pointes and a long QT interval caused by the combined use of astemizole (at recommended dosage), and ketoconazole. After discontinuation of these drugs and treatment with a temporary pacemaker, magnesium sulfate and lidocaine, the arrhythmia was no longer observed and she was discharged in good condition with a normal electrocardiogram. This case should alert clinicians to the possibility of torsade de pointes with the combined use of astemizole and ketoconazole.

Prevalence and clinical significance of left atrial thrombus in nonrheumatic atrial fibrillation

The prevalence and clinical significance of left atrial thrombus were prospectively investigated in a consecutive series of 219 patients with chronic nonrheumatic atrial fibrillation using transesophageal echocardiography. Fifteen left atrial thrombi were detected in 15 of the 219 patients (6.8%); 12 of these thrombi (80%) were confined to the left atrial appendage. Left atrial spontaneous echo contrast was visualized in 85 patients (39%). All the thrombi were found in the left atria with spontaneous echo contrast. Patients with left atrial thrombus had significantly lower left ventricular ejection fraction than those without (49 +/- 14% vs. 59 +/- 14%; P < 0.05). Multivariate analysis among clinical and transthoracic echocardiographic variables showed that left ventricular ejection fraction < 50% was the only independent predictor for the presence of left atrial thrombus. A history of thromboembolism was significantly more frequent in patients with left atrial thrombus than in those without (73% vs. 32%; P < 0.005). The presence of left atrial thrombus was more specific than spontaneous echo contrast for predicting history of thromboembolism (97% vs. 80%), but its sensitivity was significantly lower (14% vs. 73%). We conclude that: (1) Transesophageal echo-detected left atrial thrombus is not uncommon in patients with chronic nonrheumatic atrial fibrillation and is exclusively observed in those with left atrial spontaneous echo contrast. (2) Impaired left ventricular systolic function may predispose the left atrial thrombus formation. (3) Left atrial thrombus is a highly specific but insensitive predictor for thromboembolic events.

One-stage repair of pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries by a handmade trifurcated valved conduit

An 18-year-old girl with pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (MAPCAs) was reported. Her left-side pulmonary artery was absent, and the blood flow to the left lung was derived from two MAPCAs. One-stage correction, including the left-side thoracotomy and followed by the median sternotomy, was performed. A handmade trifurcated valved conduit was used to connect the right ventricle and the distal pulmonary arteries. The patient was doing well 3 years after the operation.

Pacemaker twiddler's syndrome: report of a case

A patient with symptomatic atrioventricular blockage who had been treated by permanent pacemaker implantation, developed twiddler's syndrome 16 days after implantation. The electrode lead to the pacemaker pocket had been completely displaced, with the electrode tip having moved to the outside of the subclavian vein. Complete atrioventricular block was demonstrated by electrocardiogram. Reimplantation of the same electrode at the apex of the right ventricle relieved the symptoms. The patient is regularly followed up at an outpatient clinic and continues to be well. Although twiddler's syndrome is a rare complication of pacemaker implantation, preventive measures should be undertaken especially for those judged to be at high risk.

[The effects of management difficulty and family functions on metabolic control of insulin-dependent diabetes mellitus]

This study was designed as a quantitative study. Subjects ranging from the fourth grade of primary school to the third year of senior high school were drawn from the survey project of Taipei IDDM Registry and from the Kang-Tai IDDM Association. The mothers of these diabetic children were asked to complete questionnaires. The purpose of this paper was to explore the influences of maternal stress, management difficulties and family function on self-management of diabetes and HbA1c. Results indicated that family function was positively and significantly related with self-management. There was a significant correlation between the difficulty of diet control and self-management. The total self-management, blood glucose monitoring and preventive measures for hypoglycemia were negatively correlated with HbA1c. Forty-six point six percent of the variance of self-management could be explained by the family role function, paternal education, patient's school grade, religion and difficulty of diet control. Forty-two point six percent of the variance of HbA1c could be accounted for by total self-management, payment method, difficulty of blood glucose monitoring and frequency of hospitalization due to hypoglycemia.

Acute myocardial infarction in young and very old Chinese adults: clinical characteristics and therapeutic implications

To characterize acute myocardial infarction (AMI) in young adults and octogenarians, 475 AMI patients, in age subsets, were examined. The clinical features, risk factors and in-hospital mortality were compared among 17 young patients (< 40 years), 426 patients of common age (40-79 years), and 32 very elderly patients (> or = 80 years). The octogenarian patients were mainly female (male/female ratio, 0.9 vs. 4.7 in other subgroups, P < 0.005), and had more frequent atypical presentation and postinfarctional congestive heart failure; whereas infarct size, location and development of Q-wave, major arrhythmias and cardiac wall rupture were not different among these age subsets. The most common risk factors in the young group were dyslipidemia (67%) and cigarette smoking (65%), and in the octogenarian group were dyslipidemia (52%) and hypertension (50%). Among age subsets, however, the prevalence of risk factors was not significantly different except for a relatively lower smoking rate in the octogenarians. Compared with 40- to 79-year-old patients who had predominantly multi-vessel diseases, the young patients had milder coronary atherosclerosis and were more likely to have normal coronaries (27% vs. 5%, P < 0.01). Significantly more octogenarians than young patients succumbed to AMI in the hospital (44% vs. 18%, P < 0.005), usually because of a cardiogenic complication (93%). Also, the octogenarians were less likely than the younger patients to have received thrombolytic therapy, mostly because of delayed diagnosis and arrival at the hospital, or because of old age itself.(ABSTRACT TRUNCATED AT 250 WORDS)

Down-regulation of beta-adrenergic receptors on mononuclear leukocytes induced by dobutamine treatment in patients with congestive heart failure

(+/-)-Dobutamine is a positive inotropic drug usually used to improve ventricular function in patients with congestive heart failure (CHF). However, it has been found that haemodynamic responses to dobutamine become blunted during continuous treatment. In this study we determined the time-dependent changes of beta-adrenergic receptors in CHF patients treated with dobutamine. Seven CHF patients received a continuous intravenous infusion of dobutamine (5 micrograms.kg-1 x min-1) for 96 h. Blood samples were obtained before and every 24 h after starting the therapy. The density of beta-adrenergic receptors on mononuclear leukocytes and the plasma concentrations of norepinephrine and epinephrine were determined. During dobutamine treatment the receptor density (fmol.mg-1, mean +/- SEM) gradually decreased from 42.8 +/- 4.4 (baseline) to 31.4 +/- 3.3 (P < 0.05), 25.2 +/- 4.0 (P < 0.01), 18.8 +/- 5.5 (P < 0.01) and 13.4 +/- 3.4 (P < 0.01) at 24, 48, 72 and 96 h, respectively. However, the plasma concentrations of norepinephrine and epinephrine were not significantly changed during the 96 h period of treatment. Thus, the beta-adrenergic receptors down-regulated as early as 24 h after the dobutamine treatment was begun in CHF patients. This receptor down-regulation was not associated with changes of plasma catecholamine concentrations, but was related rather to the development of drug tolerance to dobutamine.

Altered left atrial compliance after atrial appendectomy. Influence on left atrial and ventricular filling

Previous studies have shown regional differences in atrial distensibility. We studied 12 open-chest dogs to test the hypothesis that left atrial compliance is decreased after removal of the left atrial appendage and to determine the effect of altered atrial compliance on atrial reservoir and conduit function. Sonomicrometer crystal pairs were used to measure the long- and short-axis diameters of the left atrium over a wide range of intracardiac pressures and volumes obtained by intravenous hetastarch infusion both before and after suture ligation of the left atrial appendage (appendectomy). Pulmonary venous flow was measured with an ultrasonic flowmeter, and transmitral flow velocities were measured with transesophageal Doppler echocardiography. After appendectomy, the diastolic pressure-volume relation was shifted upward and to the left in six of seven dogs. The mean dynamic stiffness constant of the left atrial diastolic pressure-volume relation was significantly greater after appendectomy than before (0.20 +/- 0.11 [mean +/- SD] versus 0.14 +/- 0.08 ml-1, p < 0.01); the mean y intercept was slightly, but significantly, less after appendectomy (0.6 +/- 0.3 versus 1.3 +/- 0.6 mm Hg, p < 0.05). The left atrial reservoir volume (maximum minus minimum left atrial volume) was significantly less after appendectomy at matched left atrial pressures. The systolic to diastolic flow integral ratio of pulmonary venous flow (JFTI/KFTI), an index of the relative reservoir to conduit functions of the left atrium, increased significantly with volume infusion only before appendectomy; at matched left atrial pressure, JFTI/KFTI was significantly less afterwards.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical implications of left atrial spontaneous echo contrast in nonrheumatic atrial fibrillation

The prevalence and clinical significance of left atrial (LA) spontaneous echo contrast were investigated in 103 consecutive patients with chronic nonrheumatic atrial fibrillation (AF) using transesophageal echocardiography. LA spontaneous echo contrast was visualized in 25 of 103 patients (24.3%). Age, sex, LA diameter, left ventricular diastolic and systolic dimensions, left ventricular ejection fraction, and the percentage of lone AF were not significantly different between patients with and without LA spontaneous echo contrast; however, those with LA spontaneous echo contrast were less likely to have moderate or severe mitral regurgitation. LA thrombi were observed in 7 patients (6.8%), and all 7 thrombi were found in the atria with spontaneous echo contrast. History of cerebral ischemia or peripheral embolism, or both, was significantly more frequent in patients with than without LA spontaneous echo contrast (84 vs 18%; p less than 0.001). The presence of LA spontaneous echo contrast was highly specific (94%) and predictive for thromboembolic events (positive and negative predictive values of 84 and 82%, respectively). Thus, transesophageal echo-detected LA spontaneous echo contrast is frequently found in patients with chronic nonrheumatic AF. This phenomenon may represent a precursor of thrombus formation, and its presence is associated with an increased thromboembolic risk.

Reconstitution of an epithelial chloride channel. Conservation of the channel from mudpuppy to man

We have previously shown that monoclonal antibody E12 (MAb E12), one of several such antibodies raised against theophylline-treated Necturus gallbladder (NGB) epithelial cells, inhibits the chloride conductance in the apical membrane of that tissue. Since chloride channels are critical to the secretory function of epithelia in many different animals, we have used this antibody to determine whether the channels are conserved, and in an immunoaffinity column to isolate the channel protein. We now demonstrate that MAb E12 cross-reacts with detergent-solubilized extracts of different tissues from various species by enzyme-linked immunosorbent assay (ELISA). Western blot analysis shows that this monoclonal antibody recognizes proteins of Mr 219,000 in NGB, toad gallbladder, urinary bladder, and small intestine, A6 cells, rat colon, rabbit gastric mucosa, human lymphocytes, and human nasal epithelial cells, and inhibits the chloride conductance in toad gallbladder, rat colon, and human nasal epithelium. Detergent-solubilized protein eluted from an immunoaffinity column and then further purified via FPLC yields a fraction (Mr 200,000-220,000) which has been reconstituted into a planar lipid bilayer. There it behaves as a chloride-selective channel (PCl/PNa = 20.2 in a 150/50 mM trans-bilayer NaCl gradient) whose unit conductance is 62.4 +/- 4.6 pS, and which is blocked in the bilayer by the antibody. The gating characteristics of this channel indicate that it can exist as aggregates or as independent single channels, and that the antibody interferes with gating of the aggregates, leaving the unit channels unchanged. From these data we conclude that the protein of Mr 219,000 recognized by this monoclonal antibody is an important component of an epithelial chloride channel, and that this channel is conserved across a wide range of animal species.