Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

The prevalence and spectrum of alpha and beta thalassaemia in Guangdong Province: implications for the future health burden and population screening

AIM

Thalassaemia is a good candidate disease for control by preventive genetic programmes in developing countries. Accurate population frequency data are needed for planning the control of thalassaemia in the high risk Guangdong Province of southern China.

METHODS

In total, 13397 consecutive samples from five geographical areas of Guangdong Province were analysed for both haematological and molecular parameters.

RESULTS

There was a high prevalence of carriers of alpha thalassaemia (8.53%), beta thalassaemia (2.54%), and both alpha and beta thalassaemia (0.26%). Overall, 11.07% of the population in this area were heterozygous carriers of alpha and beta thalassaemia. The mutation spectrum of alpha and beta thalassaemia and its constitution were fully described in this area. This study reports the true prevalence of silent alpha thalassaemia in the southern China population for the first time. In addition, two novel mutations that give rise to alpha thalassaemia, one deletion resulting in beta thalassaemia, and a rare deletion (--(THAI) allele) previously unreported in mainland China were detected. The frequency of the most common mutation, the Southeast Asian type of deletion (--(SEA), accounting for 48.54% of all alpha thalassaemias) was similar to the total of two alpha(+) thalassaemia deletions (-alpha(3.7) and -alpha(4.2), accounting for 47.49% of alpha thalassaemia).

CONCLUSION

Both alpha and beta thalassaemia are widely distributed in Guangdong Province of China. The knowledge gained in this study will enable the projected number of pregnancies at risk to be estimated and a screening strategy for control of thalassaemia to be designed in this area.

Early dexamethasone therapy in preterm infants: a follow-up study

OBJECTIVES

To study the outcome at 2-year corrected age of infants who participated in a double-blind controlled trial of early (<12 hours) dexamethasone therapy for the prevention of chronic lung disease (CLD).

METHODS AND MATERIALS

A total of 133 children (70 in the control group, 63 in the dexamethasone-treated group) who survived the initial study period and lived to 2 years of age were studied. All infants had birth weights of 500 to 1999 g and had severe respiratory distress syndrome requiring mechanical ventilation within 6 hours after birth. For infants in the treatment group, dexamethasone was started at a mean age of 8.1 hours and given 0.25 mg/kg every 12 hours for 1 week and then tapered off gradually over a 3-week period. The following variables were evaluated: interim medical history, socioeconomic background, physical growth, neurologic examinations, mental and psychomotor development index score (MDI and PDI), pulmonary function, electroencephalogram, and auditory and visual evoked potential.

RESULTS

Infants in the control group tended to have a higher incidence of upper respiratory infection and rehospitalization than did the dexamethasone-treated group because of respiratory problems. Although there was no difference between the groups in somatic growth in girls, the dexamethasone-treated boys had significantly lower body weight and shorter height than the control boys (10.7 +/- 3.0 vs 11.9 +/- 2.0 kg; 84.9 +/- 5.7 vs 87.5 +/- 4.8 cm). The dexamethasone-treated group had a significantly higher incidence of neuromotor dysfunction (25/63 vs 12/70) than did the control group. The dexamethasone-treated infants also had a lower PDI score (79 +/- 26) than did the control group (87 +/- 23), but the difference was not statistically significant. Both groups were comparable in MDI, incidence of vision impairment, and auditory and visual evoked potential. Significant handicap, defined as severe neurologic defect and/or intellectual defect (MDI and/or PDI </= 69), was seen in 22 children (31.4%) in the control group and 26 (41.2%) in the dexamethasone-treated group.

CONCLUSIONS

Although early postnatal dexamethasone therapy for 4 weeks significantly reduces the incidence of CLD, this therapeutic regimen cannot be recommended at present because of its adverse effects on neuromotor function and somatic growth in male infants, detected at 2 years of age. A longer follow-up is needed. If early dexamethasone therapy is to be used for the prevention of CLD, the therapeutic regimen should be modified. The proper route of administration, the critical time to initiate the therapy, and the dosage and duration of therapy remain to be defined further.

Cdc42, dynein, and dynactin regulate MTOC reorientation independent of Rho-regulated microtubule stabilization

In migrating adherent cells such as fibroblasts and endothelial cells, the microtubule-organizing center (MTOC) reorients toward the leading edge [1-3]. MTOC reorientation repositions the Golgi toward the front of the cell [1] and contributes to directional migration [4]. The mechanism of MTOC reorientation and its relation to the formation of stabilized microtubules (MTs) in the leading edge, which occurs concomitantly with MTOC reorientation [3], is unknown. We show that serum and the serum lipid, lysophosphatidic acid (LPA), increased Cdc42 GTP levels and triggered MTOC reorientation in serum-starved wounded monolayers of 3T3 fibroblasts. Cdc42, but not Rho or Rac, was both sufficient and necessary for LPA-stimulated MTOC reorientation. MTOC reorientation was independent of Cdc42-induced changes in actin and was not blocked by cytochalasin D. Inhibition of dynein or dynactin blocked LPA- and Cdc42-stimulated MTOC reorientation. LPA also stimulates a Rho/mDia pathway that selectively stabilizes MTs in the leading edge [5, 6]; however, activators and inhibitors of MTOC reorientation and MT stabilization showed that each response was regulated independently. These results establish an LPA/Cdc42 signaling pathway that regulates MTOC reorientation in a dynein-dependent manner. MTOC reorientation and MT stabilization both act to polarize the MT array in migrating cells, yet these processes act independently and are regulated by separate Rho family GTPase-signaling pathways.

Clinical spectrum of enterovirus 71 infection in children in southern Taiwan, with an emphasis on neurological complications

An outbreak of enterovirus 71 (EV71) infection occurred in Taiwan in 1998. The clinical spectrums and laboratory findings for 97 patients with virus culture-proven EV71 infections were analyzed. Eighty-seven percent of the patients were younger than age 5 years. Hand-foot-and-mouth syndrome occurred in 79% of the children and central nervous system (CNS) involvement in 35%, including nine fatal cases. The predominant neurological presentations were myoclonus (68%), vomiting (53%), and ataxia (35%). Brain stem encephalitis was the cardinal feature of EV71 CNS involvement during this outbreak. Magnetic resonance imaging and pathological findings illustrated that the midbrain, pons, and medulla were the target areas. EV71 brain stem encephalitis can present either with cerebellar signs and an initially mild, reversible course or with overwhelming neurogenic shock and neurogenic pulmonary edema (NPE) resulting in a fatal outcome. Brain stem encephalitis that progressed abruptly to neurogenic shock and NPE was indicative of poor prognosis in this epidemic. Early aggressive treatment and close monitoring of the neurological signs are mandatory to improve the chance of survival.

Arrhythmogenic activity of cardiac muscle in pulmonary veins of the dog: implication for the genesis of atrial fibrillation

OBJECTIVE

Pulmonary veins are important foci of ectopic beats to initiate paroxysmal atrial fibrillation. The purpose of this study were to investigate the electrophysiological characteristics of excitable cells in canine pulmonary veins obtained from healthy and chronic rapid atrial pacing dogs and their responses to cardioactive agents.

METHODS

Transmembrane action potentials (APs) were recorded from multiple sites of pulmonary veins isolated from 17 healthy dogs and 14 dogs with chronic (6-8 weeks) rapid atrial pacing (780 bpm).

RESULTS

In normal superfusate, several types of electrical activities were identified, including silent electrical activity, fast response APs driven by electrical stimulation, and spontaneous fast or slow response APs (with or without early afterdepolarizations). The incidences of AP with an early afterdepolarization (93% versus 41%) was greater in chronic pacing dogs. The spontaneous activities were depressed by beta-adrenoceptor blocker, calcium channel blocker, adenosine and acetylcholine. High frequency (>8 Hz) irregular rhythms occurred spontaneously or were induced by cardioactive agents or electrical stimuli. The incidence of spontaneously occurring tachyarrhythmias was much higher in preparations from chronic pacing dogs (93%) than from control (12%). The tachyarrhythmias were suppressed by sodium channel blocker, potassium channel blocker or magnesium.

CONCLUSIONS

Pulmonary veins have arrhythmogenic ability through spontaneous activities or high-frequency irregular rhythms. The higher incidence of spontaneously occurring high-frequency irregular rhythms in chronic rapid atrial pacing dogs may account for the increased risk of atrial fibrillation in these dogs.

Effects of rapid atrial pacing on the arrhythmogenic activity of single cardiomyocytes from pulmonary veins: implication in initiation of atrial fibrillation

BACKGROUND

Pulmonary veins (PVs) are important sources of paroxysmal atrial fibrillation. Long-term rapid atrial pacing (RAP) changes atrial electrophysiology and facilitates the maintenance of atrial fibrillation. It is not clear whether RAP alters the arrhythmogenic activity of PVs. The purpose of this study was to isolate single PV cardiomyocytes from control and RAP dogs and evaluate their electrophysiological characteristics.

METHODS AND RESULTS

The action potential and ionic currents were investigated in PV cardiomyocytes from control and long-term (6 to 8 weeks) RAP (780 bpm) dogs by use of the whole-cell clamp technique. Dissociation of PVs yielded rod-shaped single cardiomyocytes without (n=91, 60%) or with (n=60, 40%) pacemaker activity. Compared with the control group, the RAP dog PV cardiomyocytes had faster beating rates (0.86+/-0.28 versus 0.45+/-0.07 Hz, P<0.05) and shorter action potential duration. The RAP dog PV cardiomyocytes with pacemaker activity have a higher incidence of delayed (59% versus 7%, P<0.001) or early (24% versus 0%, P<0.005) after depolarization. The RAP dog PV cardiomyocytes with pacemaker activity had smaller slow inward and transient outward but larger transient inward (0.017+/-0.004 versus 0.009+/-0.002 pA/pF, P<0.05) and pacemaker (0.111+/-0.019 versus 0.028+/-0.008 pA/pF, P<0.001) currents. The RAP dog PV cardiomyocytes without pacemaker activity had only smaller slow inward and transient outward and larger pacemaker currents.

CONCLUSIONS

PVs contain multiple cardiomyocytes with distinct electrophysiological characteristics. RAP changes the electrophysiological characteristics and arrhythmogenic activity of PVs.

Chromosomal changes and clonality relationship between primary and recurrent hepatocellular carcinoma

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is highly malignant and prone to recur after surgical treatment. Differentiation between a true relapse of HCC and a second primary tumor is of clinical importance. However, no convenient method is currently available.

METHODS

Comparative genomic hybridization (CGH) was used to analyze 31 pairs of initial and recurrent HCC samples obtained from patients undergoing 2 consecutive surgeries. The resulting chromosomal aberration profiles were used as genomic fingerprints to determine tumor clonalities and their relationships.

RESULTS

Eleven recurrent tumors with high clonal relationship (CR) values (>0.95) were found to be relapsed HCCs, and 11 tumors with CR values close to 0 were found to be second primary HCCs. The other 9 paired samples had inconclusive CR values between 0.95 and 0.4. Two were confirmed by hepatitis B virus integration and X chromosome inactivation analysis to be de novo cancers (CR values, 0.35 and 0. 23, respectively). Initial HCCs that subsequently relapsed accumulated more chromosomal aberration events than those that developed de novo HCC (mean, 16.1 +/- 4.5 vs. 5.4 +/- 4.8 events; P < 0.01). Also, they more frequently showed gains on chromosome arms 3q, 6p, 8q, and 17q and losses on 4q and 16p.

CONCLUSIONS

CGH is useful for chromosomal aberration study and tumor clonality analysis. More and characteristic genomic changes in the initial HCC suggest that subsequent tumor recurrence is a true relapse.

The antioxidant caffeic acid phenethyl ester induces apoptosis associated with selective scavenging of hydrogen peroxide in human leukemic HL-60 cells

Caffeic acid phenethyl ester (CAPE), an active component of propolis, has many biological and pharmacological activities including antioxidation and tumor cell cytotoxicity. We examined the type of cell death in human leukemic HL-60 cells after CAPE treatment in order to elucidate the relationship between CAPE-induced alterations of the redox state and apoptosis. CAPE treatment (6 microg/ml) resulted in marked growth inhibition up to 70.3+/-4.0% at day 2. This inhibition was partially blocked by pretreatment with N-acetyl-L-cycteine (NAC). Agarose gel electrophoresis showed evident DNA fragmentation after CAPE treatment. CAPE induced a significant decrease in mitochondrial transmembrane potential to about half of the untreated level after 6 h and a rapid depletion of intracellular glutathione (GSH) down to 41.7+/-6.0% after 1 h. Pretreatment of HL-60 cells with NAC reversed the GSH depletion and partially rescued cells from CAPE-induced apoptosis. With regard to intracellular reactive oxygen species, CAPE caused a fast and profound scavenging of H202 (19% of untreated cells after a 2-h treatment) but not of superoxide anion. These results suggest that apoptosis induced by CAPE is associated with mitochondrial dysfunction, GSH depletion and selective scavenging of H2O2 in human leukemic HL-60 cells.

Genomic characterization of the human heterotrimeric G protein alpha, beta, and gamma subunit genes

Heterotrimeric guanine nucleotide binding proteins (G proteins) transduce extracellular signals received by transmembrane receptors to effector proteins. Each subunit of the G protein complex is encoded by a member of one of three corresponding gene families. Currently, 16 different members of the alpha subunit family, 5 different members of the beta subunit family, and 11 different members of the gamma subunit family have been described in mammals. Here we have identified and characterized Bacterial Artificial Chromosomes (BACs) containing the human homologs of each of the alpha, beta, and gamma subunit genes as well as a G alpha11 pseudogene and a previously undiscovered G gamma5-like gene. The gene structure and chromosome location of each gene was determined, as were the orientations of paired genes. These results provide greater insight into the evolution and functional diversity of the mammalian G protein subunit genes.

A double-blind placebo-controlled study of the effectiveness and tolerability of oral stevioside in human hypertension

AIMS

Stevioside is a natural plant glycoside isolated from the plant Stevia rebaudiana which has been commercialized as a sweetener in Japan for more than 20 years. Previous animal studies have shown that stevioside has an antihypertensive effect. This study was to designed to evaluate the effect of stevioside in human hypertension.

METHODS

A multicentre, randomized, double-blind, placebo-controlled study was undertaken. This study group consisted of 106 Chinese hypertensive subjects with diastolic blood pressure between 95 and 110 mmHg and ages ranging from 28 to 75 years with 60 subjects (men 34, women 26; mean +/- s.d., 54.1+/-3.8 years) allocated to active treatment and 46 (men 19, women 27; mean +/- s.d., 53.7+/-4.1 years) to placebo treatment. Each subject was given capsules containing stevioside (250 mg) or placebo thrice daily and followed-up at monthly intervals for 1 year.

RESULTS

After 3 months, the systolic and diastolic blood pressure of the stevioside group decreased significantly (systolic: 166.0+/-9.4-152.6+/-6.8 mmHg; diastolic: 104.7 +/- 5.2-90.3+/-3.6 mmHg, P<0.05), and the effect persisted during the whole year. Blood biochemistry parameters including lipid and glucose showed no significant changes. No significant adverse effect was observed and quality of life assessment showed no deterioration.

CONCLUSIONS

This study shows that oral stevioside is a well tolerated and effective modality that may be considered as an alternative or supplementary therapy for patients with hypertension.

Effect of Cordyceps sinensis on the proliferation and differentiation of human leukemic U937 cells

Cordyceps sinensis is a herb medicine with antitumor activity capable of suppressing the growth of mouse Sarcoma 180 in vivo. In the present study, we have isolated polysaccharide fraction of Cordyceps sinensis (PSCS) and investigated its effect on the proliferation and differentiation of human leukemic U937 cells using an in vitro culture system. Our results showed that the conditioned medium from PSCS (10 microg/ml)-stimulated blood mononuclear cells (PSCS-MNC-CM) had an activity that could significantly inhibit the proliferation of U937 cells resulting in a growth inhibition rate of 78-83%. Furthermore, PSCS-MNC-CM treatment induced about 50% of the cells differentiating into mature monocytes/macrophages expressing nonspecific esterase (NSE) activity and the surface antigens of CD11b, CD14, and CD 68. Yet, the differentiated U937 cells also had functions of phagocytosis and superoxide production. However, PSCS alone or normal MNC-CM had no such effects. The levels of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1 were very low in normal MNC-CM, and they were greatly increased in MNC-CM prepared with PSCS stimulation. Antibody neutralization studies further revealed that the tumoricidal and differentiating effects of PSCS-MNC-CM were mainly derived from the elevated cytokines, especially IFN-gamma and TNF-alpha. These two cytokines acted synergistically on inhibiting cell growth and inducing differentiation of the target U937 cells.

Long-term outcome of radiofrequency catheter ablation for typical atrial flutter: risk prediction of recurrent arrhythmias

INTRODUCTION

Little is known about the predictors of recurrent atrial flutter or fibrillation after successful radiofrequency ablation of typical atrial flutter. In addition, there is only limited evidence suggesting that elimination of atrial flutter would modify the natural history of atrial fibrillation in patients who experienced both of these arrhythmias. The aims of the present study were to investigate the long-term results of radiofrequency catheter ablation and to examine the predictors for late occurrence of atrial fibrillation in a large population with typical atrial flutter.

METHODS AND RESULTS

The study population consisted of 144 patients (mean age 56 +/- 18 years) with successful ablation of clinically documented typical atrial flutter. In the first 50 patients, successful ablation was defined as termination and noninducibility of atrial flutter; for the subsequent 94 patients, successful ablation was defined as achievement of bidirectional isthmus conduction block and no induction of atrial flutter. The clinical and echocardiographic variables were analyzed in relation to the late occurrence of atrial flutter or fibrillation. Over the follow-up period of 17 +/- 13 months, 14 (9.7%) patients had recurrence of typical atrial flutter. In the first 50 patients, 8 (16%) had recurrence of atrial flutter, compared with only 6 (6%) of the following 94 patients. Patients with incomplete isthmus block had a significantly higher incidence of recurrent atrial flutter than those with complete isthmus block (6/16 vs 0/78, P < 0.0001) in the following 94 patients. There was no predictor for recurrence of atrial flutter after successful ablation as determined by univariate and multivariate analysis. Although successful ablation of atrial flutter eliminated atrial fibrillation in 45% of patients with a prior history of atrial fibrillation, 31 (21.5%) of 144 patients undergoing this procedure developed atrial fibrillation during the follow-up period. Univariate analysis revealed that three clinical variables were related to the occurrence of atrial fibrillation: (1) the presence of structural heart disease; (2) a history of atrial fibrillation before ablation; and (3) inducible sustained atrial fibrillation after ablation. By multivariate analysis, only a history of atrial fibrillation and inducible sustained atrial fibrillation could predict the late development of atrial fibrillation after atrial flutter ablation.

CONCLUSION

Radiofrequency catheter ablation of typical atrial flutter is highly effective and associated with a low recurrence rate of atrial flutter, but atrial fibrillation continues to be a long-term risk for patients undergoing this procedure. The presence of structural heart disease and prior spontaneous or inducible sustained atrial fibrillation increases the risk of developing atrial fibrillation.

Predicting factors of malignancy in dermatomyositis and polymyositis: a case-control study

BACKGROUND

An association between dermatomyositis (DM)/polymyositis (PM) and malignancies has been widely reported in the literature. The validity of extensive evaluation for malignancies in those patients has also been questioned for decades. Only limited papers regarding the signs of malignancy and the prognostic factors in DM/PM have been reported.

OBJECTIVES

To define the potential risk factors of concomitant neoplastic diseases in patients diagnosed as having DM/PM.

METHODS

From 1 April 1983 to 30 June 1999, 147 patients were diagnosed as having probable or definite DM/PM at the Veterans General Hospital, Taichung, Taiwan. We excluded four patients who had preceding neoplastic diseases diagnosed before DM/PM, then retrospectively reviewed the data of the remaining 143 patients and subgrouped the cases as four main types: primary idiopathic DM, primary idiopathic PM, juvenile DM/PM and amyopathic DM (ADM). We next performed univariate analysis using logistic regression to evaluate the possible predictive factors for malignancies, such as mean age at onset, gender, manifestations at onset, association with other connective tissue diseases, initial skin presentations, complications and laboratory data. Then we chose the significant factors for multivariate analysis by logistic regression, to determine the independent risk factors of malignancies in DM/PM patients.

RESULTS

Among the 143 patients, DM was the most common type (64%), followed by ADM (14%), juvenile DM/PM (13%) and PM (10%). The mean age at onset overall was 42.4 years. Other connective tissue diseases were present in 22% of all patients, especially PM (50%) and juvenile DM/PM patients (28%). Internal malignancies were present in 13% of patients, and most were associated with DM. Nasopharyngeal carcinomas (NPCs) were the most common tumours. Patients with primary idiopathic DM, with an older age at onset, higher serum creatine phosphokinase levels and male gender, had more chance of developing concomitant malignancies. Those associated with complications, especially interstitial lung diseases, had a lower risk of associated neoplasia. In multivariate analysis, an older age at onset (odds ratio 9.10) and male gender (odds ratio 4.06) were associated with greater risk of developing malignancies.

CONCLUSIONS

The two independent predictive factors for malignancy (P < 0.05) in patients with DM/PM were an older age at onset (> 45 years) and male gender. The primary idiopathic DM group was shown to have higher risk of developing internal malignancies, especially NPC. However, this was not identified as an independent predictive factor for concomitant neoplastic diseases in multivariate analysis. In addition, patients who had the complication of interstitial lung disease had a significantly lower frequency of malignancies (P < 0.001).

Right atrial focal atrial fibrillation: electrophysiologic characteristics and radiofrequency catheter ablation

INTRODUCTION

Information about focal atrial fibrillation (AF) originating from the right atrium has not been well described. The purposes of this study were to demonstrate the electrophysiologic characteristics and radiofrequency catheter ablation in patients who had right atrial focal AF.

METHODS AND RESULTS

From January 1996 to September 1998, 172 patients with clinically documented attacks of paroxysmal AF were referred to this institution for electrophysiologic study and/or radiofrequency catheter ablation. Anterior free wall, crista terminalis, and right and left superior pulmonary veins were mapped simultaneously. Eight patients (4.7%) had right atrial focal AF, consistent activation sequence, irregular fibrillation interval (mean fibrillation interval: 164 +/- 11 msec), and episodes of exit block from the initiating foci observed. The presumed ablation site was chosen on the basis of the earliest bipolar activity relative to an atrial electrogram reference during the initiation of AF. After application of 2 +/- 1 radiofrequency pulses, AF was eliminated without recurrence during the follow-up period (mean: 14 +/- 8 months; range: 3 to 25). Twenty-four-hour Holter monitoring showed that the number of atrial premature beats decreased significantly at the 3-month follow-up (4,216 +/- 411 vs 135 +/- 14 beats/day).

CONCLUSION

Right atrial focal AF is one subgroup of focal AF, and it can be cured by radiofrequency catheter ablation.

Role of atrial electrophysiology and autonomic nervous system in patients with supraventricular tachycardia and paroxysmal atrial fibrillation

OBJECTIVES

The purposes of this study were to evaluate the atrial electrophysiology and autonomic nervous system in patients who had paroxysmal supraventricular tachycardia (PSVT) associated with paroxysmal atrial fibrillation (PAF).

BACKGROUND

PAF frequently appeared in patients with PSVT. However, the critical determinants for the occurrence of PAF were not clear.

METHODS

This study population consisted of 50 patients who had PSVT with (n=23) and without (n=27) PAF. Atrial pressure, atrial size, atrial effective refractory periods (AERPs), and AERP dispersion were evaluated during baseline and PSVT, respectively. Twenty-four hour heart rate variability and baroreflex sensitivity (BRS) were also examined.

RESULTS

There was greater baseline AERP dispersion in patients with PAF than in those without PAF. The atrial pressure, atrial size, AERPs in the right posterolateral atrium and distal coronary sinus, and AERP dispersion were increased during PSVT as compared with those during baseline. Patients with PAF had greater AERP dispersion than those without PAF during PSVT. The differences of atrial size, right posterolateral AERP, and AERP dispersion between baseline and PSVT were greater in patients with PAF than in those without PAF. BRS, but not heart rate variability, was higher in patients with PAF than in those without PAF. Univariate analysis showed that higher BRS (>4.5 ms/mm Hg, p=0.0002, odds ratio=16.1), AERP dispersion during PSVT (>40 ms, p=0.0008, odds ratio=9.7), and increase of right atrial area during PSVT (>2 cm2, p=0.016, odds ratio=10.7) were significantly correlated with the occurrence of PAF in patients with PSVT.

CONCLUSIONS

Disturbed atrial electrophysiology and higher vagal reflex could play important roles in the genesis of PAF in patients with PSVT.

Effect of caffeic acid phenethyl ester, an antioxidant from propolis, on inducing apoptosis in human leukemic HL-60 cells

Caffeic acid phenethyl ester (CAPE) is an active component isolated from propolis. The aim of this study was to investigate the mechanism of CAPE-induced apoptosis in human leukemic HL-60 cells. It was found that CAPE entered HL-60 cells very quickly and then inhibited their survival in a concentration- and time-dependent manner. CAPE induced characteristic DNA fragmentation and morphological changes typical of apoptosis in these cells. Estimation of the apoptotic percentage showed a time-dependent increase after CAPE (6 microg/mL) treatment (up to 66.7 +/- 2.0% at 72 h). Treatment with CAPE caused rapid activation of caspase-3 after 4 h, down-regulation of Bcl-2 expression after 6 h, and up-regulation of Bax expression after 16 h. These results suggest that CAPE is a potent apoptosis-inducing agent; its action is accompanied by activation of caspase-3, down-regulation of Bcl-2, and up-regulation of Bax in human leukemic HL-60 cells.

Is 8-mm more effective than 4-mm tip electrode catheter for ablation of typical atrial flutter?

BACKGROUND

The prospective, randomized study comparing 4- with 8-mm tip electrodes for radiofrequency linear ablation of typical atrial flutter is not available.

METHODS AND RESULTS

A total of 104 consecutive patients with typical atrial flutter were randomly assigned to undergo radiofrequency linear ablation using a 4- (Group I, n=54) or 8-mm tip electrode (Group II, n=50) catheter (temperature-control model, preset 70 degrees C). If complete bidirectional isthmus block could not be achieved after 5 pulses, the ablation catheter was changed to the other type; the maximal radiofrequency pulse number was limited to <10 pulses. Complete or incomplete isthmus conduction block was assessed by activation sequence in a multielectrode Halo catheter during low lateral right atrial and proximal coronary sinus pacing. Before shifting to the other catheter type, the 8-mm electrode catheter achieved higher complete isthmus block rate (92% versus 67%, P<0.05) with fewer pulses (2+/-1 versus 3+/-1, P<0.05), shorter procedure time (24+/-15 versus 31+/-12 minutes, P<0.05), and shorter fluoroscopic time (14+/-10 versus 23+/-15 minutes, P<0.05). After 5 failed ablation pulses, 12 (67%) of 18 patients in group I attained complete isthmus block by using an 8-mm tip catheter, but none of 4 patients in group II achieved complete block by changing to a 4-mm tip catheter.

CONCLUSIONS

The 8-mm tip electrodes are more effective than the standard 4-mm length electrodes in linear ablation for typical atrial flutter. This clinical benefit may be of particular value for some patients with broad and/or thick isthmus.

Protein splicing of the yeast TFP1 intervening protein sequence: a model for self-excision

Protein splicing is the protein analogue of RNA splicing in which the central portion (spacer) of a protein precursor is excised and the amino- and carboxy-terminal portions of the precursor reconnected. The yeast Tfp1 protein undergoes a rapid protein splicing reaction to yield a spliced 69 kDa polypeptide and an excised 50 kDa spacer protein. We have demonstrated that the 69 kDa species arises by reformation of a bona fide peptide bond. Deletion analyses indicate that only sequences in the central spacer protein of the Tfp1 precursor are critical for the protein splicing reaction. A fusion protein in which only the Tfp1 spacer domain was inserted into an unrelated protein also underwent efficient splicing, demonstrating that all of the information required for protein splicing resides within the spacer domain. Alteration of Tfp1p splice junction residues blocked or kinetically impaired protein splicing. A protein splicing model is presented in which asparagine rearrangement initiates the self-excision of the spacer protein from the Tfp1 precursor. The Tfp1 spacer protein belongs to a new class of intervening sequences that are excised at the protein rather than the RNA level.

The effects of exercise training on walking function and perception of health status in elderly patients with peripheral arterial occlusive disease

OBJECTIVE

To determine the effects of 12-week exercise programme on ambulatory function, free-living daily physical activity and health-related quality of life in disabled older patients with intermittent claudication.

DESIGN

Prospective, randomized controlled trial.

SETTING

University Medical Center and Veterans Affairs Medical Center, Taipei, Taiwan.

SUBJECTS

Thirty-two of 64 patients with Fontaine stage II peripheral arterial occlusive disease (PAOD) were randomized to exercise training and 32 to usual care control. Five patients from the exercise group and six patients from the control group dropped out, leaving 27 and 26 patients, respectively, completing the study in each group.

INTERVENTIONS

Twelve weeks of treadmill exercise training.

MAIN OUTCOME MEASURES

Treadmill walking time to onset of claudication pain and to maximal claudication pain, 6-min walk distance, self-reported ambulatory ability and perceived health-related quality of life (QOL).

RESULTS

Compliance of exercise programme was 83% of the possible sessions. Exercise training increased treadmill walking time to onset of claudication pain by 88% (P < 0.001), time to maximal pain by 70% (P < 0.001), and 6-min walk distance by 21% (P < 0.001).

SUBJECTS

Perception of health-related QOL improved from 12% to 178% in the exercise group. These improvements were significantly better than the changes in the control group (P < 0.05).

CONCLUSIONS

Significant improvements in claudication following 12-week exercise training in elderly PAOD patients were observed. Increase in treadmill walking time to maximal claudication pain in these patients translated into the improvement of perceived physical health, which enabled the patients to become more functionally independent.

Effects of prenatal exposure to PCBs on the neurological function of children: a neuropsychological and neurophysiological study

To determine the long-term neurotoxicity of prenatal exposure to polychlorinated biphenyls (PCBs), 54 children--27 'Yu-Cheng' ('oil disease') children and 27 controls--were administered a battery of tests, including the WISC-R, auditory event-related potentials (P300), pattern visual evoked potentials (P-VEPs) and somatosensory evoked potentials (SSEPs). Full-scale IQ scores on the WISC-R were lower for the Yu-Cheng group than for the control group. Mean P300 latencies were significantly longer, and P300 amplitude significantly more reduced, in the Yu-Cheng group than in the control group at Cz and Pz. There were no significant difference in peak latencies and amplitudes between the two groups for P-VEPs and SSEPs. These findings suggest that prenatal exposure to PCBs tends to affect high cortical function rather than the sensory pathway in the developing brain.

The effect of stevioside on blood pressure and plasma catecholamines in spontaneously hypertensive rats

Stevioside is a sweet-tasting glycoside, composed of stevia, a diterpenic carboxylic alcohol with three glucose molecules, mainly used as a substitute for non-alcoholic sweetener. It has previously been shown to reduce blood pressure in studies in animals and human. The effect of intravenous stevioside on the blood pressure was studied in spontaneously hypertensive rats (SHR). The hypotensive effect on both systolic and diastolic blood pressure was dose-dependent for intravenous doses of 50, 100 and 200 mg/kg in conscious SHR. The maximum reductions in systolic and diastolic blood pressure were 31.4 +/- 4.2% and 40.8 +/- 5.6% (mean +/- SEM) respectively and the hypotensive effect lasted for more than 60 min with a dose of 200 mg/kg. Serum dopamine, norepinephrine and epinephrine levels were not changed significantly 60 min after intravenous injection of stevioside 100 mg/kg in anesthetized SHR. The present data show that stevioside given intravenously to conscious SHR was effective in blood pressure reduction and there was no change in serum catecholamines in anaesthetized animals with this natural compound.

Phylogeography of Kandelia candel in East Asiatic mangroves based on nucleotide variation of chloroplast and mitochondrial DNAs

Vivipary with precocious seedlings in mangrove plants was thought to be a hindrance to long-range dispersal. To examine the extent of seedling dispersal across oceans, we investigated the phylogeny and genetic structure among East Asiatic populations of Kandelia candel based on organelle DNAs. In total, three, 28 and seven haplotypes of the chloroplast DNA (cpDNA) atpB-rbcL spacer, cpDNA trnL-trnF spacer, and mitochondrial DNA (mtDNA) internal transcribed spacer (ITS) were identified, respectively, from 202 individuals. Three data sets suggested consistent phylogenies recovering two differentiated lineages corresponding to geographical regions, i.e. northern South-China-Sea + East-China-Sea region and southern South-China-Sea region (Sarawak). Phylogenetically, the Sarawak population was closely related to the Ranong population of western Peninsula Malaysia instead of other South-China-Sea populations, indicating its possible origin from the Indian Ocean Rim. No geographical subdivision was detected within the northern geographical region. An analysis of molecular variance (AMOVA) revealed low levels of genetic differentiation between and within mainland and island populations (phiCT = 0.015, phiSC = 0.037), indicating conspicuous long-distance seedling dispersal across oceans. Significant linkage disequilibrium excluded the possibility of recurrent homoplasious mutations as the major force causing phylogenetic discrepancy between mtDNA and the trnL-trnF spacer within the northern region. Instead, relative ages of alleles contributed to non-random chlorotype-mitotype associations and tree inconsistency. Widespread distribution and random associations (chi2 = 0.822, P = 0.189) of eight hypothetical ancestral cytotypes indicated the panmixis of populations of the northern geographical region as a whole. In contrast, rare and recently evolved alleles were restricted to marginal populations, revealing some preferential directional migration.

Characterization of glycine-N-methyltransferase-gene expression in human hepatocellular carcinoma

Messenger RNA differential display was used to study liver-gene expression in paired tumor and non-tumor tissues from hepatocellular carcinoma (HCC) patients. mRNA differential display and Northern-blot analyses showed that a 0.8-kb cDNA fragment was diminished or absent from the tumorous tissues of 7 HCC patients. The cDNA fragment was sequenced and found to have 98.7% nucleotide sequence homology with human glycine-N-methyltransferase cDNA (GNMT). In addition, there was no detectable level of GNMT expression in 4 human HCC cell lines, SK-Hep1, Hep 3B, HuH-7 and HA22T, examined by Northern-blot assay. A full-length GNMT cDNA clone-9-1-2 was obtained by screening a Taiwanese liver cDNA library. In comparison with the GNMT cDNA sequence reported elsewhere, clone 9-1-2 had 4 nucleotide differences resulting in 1 amino-acid change. Immunohistochemical staining with rabbit anti-recombinant GNMT serum showed that GNMT protein almost completely disappeared in liver-cancer cells, while it was abundant in the non-tumorous liver cells. Down-regulation of GNMT gene expression may be involved in the pathogenesis of liver cancer.