Right axillosubclavian vein thrombosis resolved by percutaneous rheolytic thrombectomy in a patient with a recurrent gastrointestinal stromal tumour undergoing imatinib mesylate treatment

The manifestation and management of spontaneous axillosubclavian vein thrombosis in patients with gastrointestinal stromal tumour (GIST) undergoing oral chemotherapy have never been described. We report a patient with a recurrent GIST who was receiving maintenance imatinib yet developed a right axillosubclavian vein thrombotic occlusion. The occluded vein was unresponsive to systemic anticoagulation but was reopened by percutaneous rheolytic thrombectomy and has shown good long-term patency. Thus, for patients with recurrent GIST undergoing imatinib therapy, axillosubclavian vein thrombosis might manifest as a complication and could be managed with rheolytic thrombectomy, which thoroughly removes intravascular thrombus and effectively re-vascularizes the thrombosed vessel uneventfully.

Impact of chronic advanced aortic regurgitation on the perioperative outcome of noncardiac surgery

BACKGROUND

Whether and how chronic advanced aortic regurgitation (AR) impacts the perioperative outcome of noncardiac surgery remains unclear.

METHODS

From November 1999 to December 2006, all patients undergoing noncardiac operations and ever examined by echocardiography within the last 6 months were screened. Those with chronic moderate-severe or severe AR were enrolled, provided they were not already trachea-intubated or aortic valve operated, and the surgery was not performed under local anesthesia. Case-matched subjects without significant AR served as controls. The perioperative outcomes of these patients were analyzed, and independent prognostic correlates were investigated by multivariate logistic regression analysis.

RESULTS

A total of 167 patients (male 131, mean age of 75 years) complying with the enrollment criteria were studied. Compared with the other 167 case-matched control peers, patients with advanced AR risked potential hazards of serious hemodynamic instability (0.6%) and circulatory collapse (1.2%) during surgery despite the similar incidence of overall cardiac adverse events, and were further distressed with more cardiopulmonary complications (16.2% vs. 5.4%, P=0.003) and in-hospital deaths (9% vs. 1.8%, P=0.008) post-operatively. Multivariate regression analysis confirmed the correlation of advanced AR with perioperative mortality, and identified depressed left ventricular function, renal dysfunction, high surgical risk, and lack of cardiac medication as predictors of in-hospital death.

CONCLUSION

Chronic advanced AR complicates the perioperative outcome of noncardiac surgery as reflected by frequent cardiopulmonary morbidities and in-hospital deaths, especially when coexisting with specified high-risk clinical and surgical characteristics.

A genome-wide association study identifies new loci for ACE activity: potential implications for response to ACE inhibitor

Because angiotensin-converting enzyme (ACE) activity is implicated widely in biological systems, we aimed to identify its novel quantitative trait loci for the purposes of understanding ACE activity regulation and pharmacogenetics relating to ACE inhibitor (ACEI). We performed a two-stage genome-wide association study: (1) from 400 young-onset hypertension (YOH) subjects and (2) a confirmation study with an additional 623 YOH subjects. In the first stage, eight single nucleotide polymorphisms (SNPs) of the ACE structural gene and one SNP of ABO genes were significantly associated with ACE activity. SNP rs4343 in exon17 near the well-known insertion/deletion polymorphism had the strongest association. We confirmed in the second stage that three SNPs: rs4343 in ACE gene (P=3.0 x 10⁻²⁵), rs495828 (P=3.5 x 10⁻⁸) and rs8176746 (P=9.3 x 10⁻⁵) in ABO gene were significantly associated with ACE activity. We further replicated the association between ABO genotype/blood types and ACE activity in an independent YOH family study (428 hypertension pedigrees), and showed a potential differential blood pressure response to ACEI in subjects with varied numbers of ACE-activity-raising alleles. These findings may broaden our understanding of the mechanisms controlling ACE activity and advance our pharmacogenetic knowledge on ACEI.

Caffeic acid phenethyl ester inhibits arterial smooth muscle cell proliferation and migration in vitro and in vivo using a local delivery system

Over the last two decades, significant advances have been made in percutaneous coronary intervention (PCI) for the treatment of atherosclerotic plaques. However, restenosis after PCI still challenges both vascular biologists and interventional cardiologists. In this study, we found that caffeic acid phenethyl ester (CAPE) displayed an inhibitory effect on human coronary smooth muscle cell (HCSMC) growth and migration. Flow cytometry analysis showed that the ratio of S phase increased after exposing cells to CAPE for 48-72 h. Pretreatment of cells with CAPE significantly suppressed Cyclin E, CDK2, Cyclin A, and proliferating-cell nuclear antibody expression. We demonstrated that CAPE inhibited AKT 1 and MEK1/2 activation. Using a local infusion system, CAPE was able to regress the intima thickening of the iliac artery in rabbits after balloon injury. The percentage of intimal thickening decreased significantly to 55.0 +/- 0.12 in the group after local CAPE infusion compared to the group after saline infusion (98.3 +/- 0.41%). In conclusion, CAPE can inhibit the proliferation and migration of HCSMCs by inducing cell cycle arrest. Decreased cell cycle genes and associated signaling pathway target gene expression may mediate anti-proliferative and anti-migration effects of CAPE. Furthermore, CAPE prevents intima thickening in rabbits after balloon angioplasty. These results indicate that CAPE may have therapeutic relevance for the prevention of restenosis during PCI in the treatment of coronary artery diseases.

A standardized extract of Ginkgo biloba suppresses doxorubicin-induced oxidative stress and p53-mediated mitochondrial apoptosis in rat testes

BACKGROUND AND PURPOSE

Doxorubicin evokes oxidative stress and precipitates cell apoptosis in testicular tissues. The aim of this study was to investigate whether the Ginkgo biloba extract 761 (EGb), a widely used herbal medicine with potent anti-oxidant and anti-apoptotic properties, could protect testes from such doxorubicin injury.

EXPERIMENTAL APPROACH

Sprague-Dawley male rats (8 weeks old) were given vehicle, doxorubicin alone (3 mg kg(-1) every 2 days for three doses), EGb alone (5 mg kg(-1) every 2 days for three doses), or EGb followed by doxorubicin (each dose administered 1 day after EGb). At 7 days after the first drug treatment oxidative and apoptotic testicular toxicity was evaluated by biochemical, histological and flow cytometric analyses.

KEY RESULTS

Compared with controls, testes from doxorubicin-treated rats displayed impaired spermatogenesis, depleted haploid germ cell subpopulations, increased lipid peroxidation products (malondialdehyde), depressed antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase and glutathione), reduced antioxidant enzyme expression (superoxide dismutase) and elevated apoptotic indexes (pro-apoptotic modulation of Bcl-2 family proteins, intensification of p53 and Apaf-1, release of mitochondrial cytochrome c, activation of caspase-3 and increase of terminal deoxynucleotidyl transferase nick-end labelling/sub-haploid cells), while EGb pretreatment effectively alleviated all of these doxorubicin-induced abnormalities in testes.

CONCLUSIONS AND IMPLICATIONS

These results demonstrate that EGb protected against the oxidative and apoptotic actions of doxorubicin on testes. EGb may be a promising adjuvant therapy medicine, potentially ameliorating testicular toxicity of this anti-neoplastic agent in clinical practice.

Bivariate genome-wide scan for metabolic phenotypes in non-diabetic Chinese individuals from the Stanford, Asia and Pacific Program of Hypertension and Insulin Resistance Family Study

AIMS/HYPOTHESIS

Hypertension, obesity, impaired glucose tolerance and dyslipidaemia are metabolic abnormalities that often cluster together more often than expected by chance alone. Since these metabolic variables are highly heritable and are at least partially genetically determined, the clustering of defects in these traits implies that pleiotropic effects, where a common set of genes influences more than one trait simultaneously, are likely.

METHODS

We conducted bivariate linkage analyses for highly correlated traits, aiming to dissect the genetic architecture affecting these traits, in 411 Chinese families participating in the Stanford Asia-Pacific Program of Hypertension and Insulin Resistance Study.

RESULTS

We confirmed the pleiotropic effects of the locus at 37 cM on chromosome 20 on the following pairs: (1) fasting insulin and insulin AUC (empirical p = 0.0006); (2) fasting insulin and homeostasis model assessment of beta cell function (HOMA-beta) (empirical p = 0.0051); and (3) HOMA of insulin resistance (IR) and HOMA-beta (empirical p = 0.0044). In addition, the peak logarithm of the odds (LOD) scores of linkage between a chromosomal locus and a trait for the pair fasting insulin and HOMA-IR rose to 5.10 (equivalent LOD score in univariate analysis, LOD([1]) = 4.01, empirical p = 8.0 x 10(-5)) from 3.67 and 3.42 respectively for these two traits in univariate analysis. Additional significant linkage evidence, not shown in single-trait analysis, was identified at 45 cM on chromosome 16 for the pair 1 h insulin and the AUC for insulin, with a LOD score of 4.29 (or LOD([1]) = 3.27, empirical p = 2.0 x 10(-4)). This new locus is also likely to harbour the common genes regulating these two traits (p = 1.73 x 10(-6)).

CONCLUSIONS/INTERPRETATION

These data help provide a better understanding of the genomic structure underlying the metabolic syndrome.

Severe pulmonary hypertension complicates postoperative outcome of non-cardiac surgery

BACKGROUND

Whether and how pulmonary hypertension (PH) impacts perioperative outcome in non-cardiac surgery is incompletely understood.

METHODS

From November 1999, all patients undergoing non-cardiac, non-local anaesthetic surgery and ever examined by echocardiography within 30 days before surgery were screened. Those having echocardiographic pulmonary artery systolic pressure >70 mm Hg were enrolled provided they were not already intubated. Case-matched peers with normal pulmonary pressures served as controls. Perioperative outcomes were compared between the two groups, and predictors of adverse perioperative outcomes were investigated by multivariate logistic regression analysis.

RESULTS

From November 1999 to August 2004, a total of 62 patients (male 38, mean age 67 yr) with PH were found. Compared with the case-matched controls, patients with PH experienced equivalently smooth operative courses, but significantly more frequent postoperative heart failure (9.7 vs 0%, P = 0.028), delayed tracheal extubation (21 vs 3%, P = 0.004), and in-hospital deaths (9.7 vs 0%, P = 0.028). Multivariate regression analysis identified emergency surgery [odds ratio (OR), 44.738; P = 0.028], coronary artery disease (CAD; OR, 9.933; P = 0.042), and systolic pulmonary artery pressure (OR, 1.101; P = 0.026) as independent predictors of postoperative mortality and surgery-specific cardiac risk level (OR, 6.791; P = 0.033) and CAD (OR 6.546, P = 0.017) as predictors of morbidity.

CONCLUSION

PH is an important predictor of adverse cardiopulmonary outcome in non-cardiac surgery as reflected by markedly increased postoperative complications, especially in patients with coexistent high-risk clinical and surgical characteristics.

Progressive action potential duration shortening and the conversion from atrial flutter to atrial fibrillation in the isolated canine right atrium

OBJECTIVES

We sought to evaluate the effects of progressive shortening of the action potential duration (APD) on atrial wave front stability.

BACKGROUND

The mechanisms of conversion from atrial flutter to atrial fibrillation (AF) are unclear.

METHODS

Isolated canine right atria were perfused with 1 to 5 micromol/l of acetylcholine (ACh). We mapped the endocardium by using 477 bipolar electrodes and simultaneously recorded transmembrane potentials from the epicardium. The APD(90) was measured during regular pacing (S(1)) with cycle lengths of 300 ms. Atrial arrhythmia was induced by a premature stimulus (S(2)).

RESULTS

At baseline, only short runs of repetitive beats (<10 cycles) were induced. After shortening the APD(90) from 124 +/- 15 ms to 72 +/- 9 ms (p < 0.01) with 1 to 2.5 micromol/l of ACh, S(2) pacing induced single, stable and stationary re-entrant wave fronts (307 +/- 277 cycles). They either anchored to pectinate muscles (5 tissues) or used pectinate muscles as part of the re-entry (4 tissues). When ACh was raised to 2.5 to 5 micromol/l, the APD(90) was further shortened to 40 +/- 12 ms (p < 0.01); S(2) pacing induced in vitro AF by two different mechanisms. In most episodes (n = 13), AF was characterized by rapid, nonstationary re-entry and multiple wave breaks. In three episodes with APD(90) <30 ms, AF was characterized by rapid, multiple, asynchronous, but stationary wave fronts.

CONCLUSIONS

Progressive APD shortening modulates atrial wave front stability and converts atrial flutter to AF by two mechanisms: 1) detachment of stationary re-entry from the pectinate muscle and the generation of multiple wave breaks; and 2) formation of multiple, isolated, stationary wave fronts with different activation cycle lengths.

A randomized, double-blind, placebo-controlled, 8-week study to evaluate the efficacy and safety of once daily atorvastatin (10 mg) in patients with elevated LDL-cholesterol

Lowering of serum cholesterol levels by pharmacologic intervention with statins reduces the incidence of cardiovascular events in subjects with and without atherosclerotic manifestations. In an 8-week, randomized, double-blind study we compared the efficacy and safety of the new compound atorvastatin for reducing LDL-cholesterol (LDL-C) with placebo in an Asian patient cohort. Patients with LDL-C between 160 mg/dl and 250 mg/dl were randomly assigned to treatment with 10 mg atorvastatin or placebo once daily for 8 weeks. At the end of weeks 4 and 8 of the randomized phase, the serum concentrations of lipid parameters as well as safety parameters were determined. Fifty-four patients (32 males and 22 females) were enrolled. Twenty-six patients were assigned to the treatment group. The primary end-point, LDL-C, was reduced by 40% and 42% after 4 and 8 weeks of treatment in the atorvastatin treated patients (p<0.001). The reductions in total cholesterol and triglycerides were up to 31% and 23%, respectively. The HDL-C levels increased up to 11% (p=0.043). There were no significant adverse events. Transient increases in CPK levels (10 times) without myalgia were identified in 1 patient. Atorvastatin, 10 mg/day produced significant reductions in LDL-C, total cholesterol and triglycerides and an elevation of HDL-C levels when used as an adjunct to diet in hyperlipidemic patients. The majority of the clinical effects could be attained by week 4. The overall safety profile of atorvastatin was similar to that of placebo. Atorvastatin was considered to be well tolerated in this patient cohort.

Genetic variation in the human urea transporter-2 is associated with variation in blood pressure

The kidney, by regulating the volume of fluid in the body, plays a key role in regulating blood pressure (BP). The kidney uses primarily sodium and, to a lesser extent, urea to maintain the appropriate volume of fluid. Genetic variation in proteins that determine sodium reabsorption and excretion is known to significantly influence BP. However, the influence of genetic variation in urea transporters on BP has not been examined. We determined therefore whether nucleotide variation in the kidney-specific human urea transporter, HUT2, is associated with variation in BP. After determining the genomic structure of the coding sequence, seven single nucleotide polymorphisms (SNPs) were identified. Two of the SNPs result in Val/Ile and Ala/Thr amino acid substitutions at positions 227 and 357 in the HUT2 open reading frame, respectively. Another SNP is silent and four others are in introns or the 3' untranslated region. Over 1000 hypertensive and low-normotensive individuals of Chinese origin were typed for five of these SNPs using a high-throughput genotyping method. The Ile227 and Ala357 alleles were associated with low diastolic BP in men but not women, with odds ratios 2.1 [95% confidence interval (CI) 1.5-2.7, P < 0.001] and 1.5 (95% CI 1.2-1.8, P < 0.001), respectively. There was a similar trend for systolic BP, and odds ratios for the Ile227 and Ala357 alleles were 1.7 (95% CI 1.2-2.3, P = 0.002) and 1.3 (95% CI 1.1-1.6, P = 0.007), respectively, in men.

High-throughput genotyping with single nucleotide polymorphisms

To make large-scale association studies a reality, automated high-throughput methods for genotyping with single-nucleotide polymorphisms (SNPs) are needed. We describe PCR conditions that permit the use of the TaqMan or 5' nuclease allelic discrimination assay for typing large numbers of individuals with any SNP and computational methods that allow genotypes to be assigned automatically. To demonstrate the utility of these methods, we typed >1600 individuals for a G-to-T transversion that results in a glutamate-to-aspartate substitution at position 298 in the endothelial nitric oxide synthase gene, and a G/C polymorphism (newly identified in our laboratory) in intron 8 of the 11-beta hydroxylase gene. The genotyping method is accurate-we estimate an error rate of fewer than 1 in 2000 genotypes, rapid-with five 96-well PCR machines, one fluorescent reader, and no automated pipetting, over one thousand genotypes can be generated by one person in one day, and flexible-a new SNP can be tested for association in less than one week. Indeed, large-scale genotyping has been accomplished for 23 other SNPs in 13 different genes using this method. In addition, we identified three "pseudo-SNPs" (WIAF1161, WIAF2566, and WIAF335) that are probably a result of duplication.

The incidence of coronary artery disease in patients with symptomatic bradyarrhythmias

Symptomatic bradyarrhythmia occurs most often in aged patients. Most of these patients have multiple coronary risk factors and present with angina-like symptoms. The coexistence of CAD not only has major effects on their prognosis but also influences the long-term care. This study was designed to evaluate the incidence of coexistent CAD in patients with symptomatic bradyarrhythmias and its relationship to conventional coronary risk factors in Chinese people. From May 1996 to April 1998, we prospectively studied all consecutive patients admitted to our institution for symptomatic bradyarrhythmias requiring permanent pacemaker implantation. Coronary angiographies were performed non-selectively at the same session of pacemaker implantation. Based on the presence or absence of CAD, patients were divided into two groups for analysis. Multivariate logistic regression analysis was performed to determine independent predictors of CAD including sex, age, diabetes mellitus (DM), hypertension, hypercholesterolemia, and smoking. The odds-ratio (OR) and 95% confidence interval (CI) were determined. A total of 113 patients [68 males and 45 females, mean age 70.4+/-8.2 years old (range 45-86)] were included in our study. The diagnosis was sick sinus syndrome in 69 patients (61%) and atrioventricular block in 44 patients (39%). The incidence of CAD based on coronary angiography was 20%. The nodal-related artery was seldom involved among patients with coexistent CAD and symptomatic bradyarrhythmias (9%), and most patients had significant stenosis over LAD (74%). The baseline characteristics and presenting symptoms were not different statistically between patients with or without CAD. Hypercholesterolemia (OR 6.6, 95% CI 2.0-22.2, p=0.002) and DM (OR 4.7, 95% CI 1.3-17.2, p=0.020) were the two most significant independent predictors of CAD. In our patients with symptomatic bradyarrhythmias requiring permanent cardiac pacing, the incidence of CAD was 20% as determined by coronary angiography (CAG). Hypercholesterolemia and DM were the two most significant independent predictors for CAD in these patients. The nodal artery was seldom involved in patients with coexistent CAD and symptomatic bradyarrhythmias.

Incipient speciation by sexual isolation in Drosophila: concurrent evolution at multiple loci

Drosophila melanogaster from Zimbabwe and nearby regions shows strong but asymmetric sexual isolation from its cosmopolitan counterparts. By creating stable chromosome-substitution lines, earlier studies were able to show that the two major autosomes have very large effects on both male mating success and female mating preference. In this study, we genetically dissect this sexual isolation by recombination analysis between a whole-chromosome substitution line (which carries a Zimbabwe-derived third chromosome) and a strain with seven visible markers on that chromosome. Four loci are responsible for male mating success and three others are found to control female mating preference. Because male and female traits are not closely linked, their strong association among isofemale lines is most likely a reflection of sexual selection in nature. The results suggest that a large number of behavioral loci may evolve concurrently in the incipient stage of speciation before other aspects of reproductive isolation (such as hybrid sterility) have become evident. The results shed light on the population genetic processes underlying the formation of nascent species, as well as modes of speciation.

Relation between the rapid focal activation in the pulmonary vein and the maintenance of paroxysmal atrial fibrillation

This case report describes a patient with drug refractory paroxysmal atrial fibrillation (PAF). Rapid focal activations with multiple sharp spikes were continuously identified inside the left superior pulmonary vein (PV) during sustained AF. Among seven episodes of AF, cessation of rapid focal activations coincided with the conversion of AF to flutter (n = 4) or immediate AF termination (n = 3). Guided by sharp spikes in the PV, abrupt termination of AF occurred during radiofrequency energy application. Conclusively, rapid focal activations inside the PV are critical in AF maintenance. Cessation of these rapid focal activations underlies the mechanism by which AF converts to flutter.

Orbital adenocarcinoma of lacrimal gland origin in a dog

A 13-year-old intact female mixed-breed dog was presented for a progressive enlargement of the right eye, which had been treated previously for conjunctivitis. A round, firm mass, approximately 4 cm in diameter, was protruding from the superotemporal aspect of the right orbit, displacing the eyeball anteriorly and ventromedially. The mass was encapsulated, distinct from the eyeball, and not associated with the eyelids. On cut surface, there was a pale multilobulated periphery, with a dark red, soft, and depressed core. Histologically, tumor cells formed cords and tubules, which were stained with mouse anti-human cytokeratin antibody AE1/AE3. Residual glands were serous, and the majority of tumor cells were negative for mucin. The supraorbital location, encapsulation, and residual serous glands suggest that this mass was a low-grade adenocarcinoma of the lacrimal gland.

Pulmonary veins and ligament of Marshall as sources of rapid activations in a canine model of sustained atrial fibrillation

BACKGROUND

In dogs, chronic rapid pacing may result in sustained atrial fibrillation (AF). However, activation patterns in pacing-induced sustained AF are unclear.

METHODS AND RESULTS

We induced sustained AF (>48 hours) in 6 dogs by rapid pacing for 139+/-84 days. We then performed computerized atrial epicardial mappings and recorded the activations in the ligament of Marshall (LOM) and the pulmonary veins (PVs). During AF, mean activation cycle length in the right atrial free wall (126+/-17 ms) was significantly longer than that in the left atrial free wall (96+/-5 ms, P:=0.006). In addition, mean activation cycle length in the left atrial free wall was significantly longer than that in the LOM (84+/-5 ms, P:<0.001), the left inferior PV (81+/-4 ms, P:=0.001), and the left superior PV (85+/-7 ms, P:=0.003). Similarly, the dominant frequency was highest in the LOM and the PVs (range 11.2 to 13.3 Hz), followed by the left and right atria (P:<0.001). In all dogs studied, rapid and complicated electrograms were consistently observed at the LOM and the PVs. During AF, both wandering wavelets and organized reentry were present. There were more wave fronts in the left atrium than in the right atrium (P:<0.001).

CONCLUSIONS

In chronic pacing-induced sustained AF, the LOM and the PVs are the sources of rapid activations. The mechanism by which the left atrium activates faster and has more wave fronts than the right atrium may relate to the fact that the left atrium is closer to the sources of rapid activations.

Successful resuscitation of patient with massive coronary air embolism occluding two vessels during coronary angiography--a case report

Massive coronary air embolism is usually disastrous although successful resuscitation has been reported previously. To what extent a patient with coronary air embolism can be resuscitated is not known. The authors report a rare case of massive air embolism to the left coronary arteries and successful resuscitation by vigilantly maintaining an effective driving force to dissipate the air lock.

Sudden changes in heart rate variability during the 1999 Taiwan earthquake

Sympathovagal imbalance resulting from reactions to an earthquake was not prominent in patients who were taking beta-blockers.

Sex in Drosophila mauritiana: a very high level of amino acid polymorphism in a male reproductive protein gene, Acp26Aa

Many genes pertaining to male reproductive functions have been shown to evolve rapidly between species, and evidence increasingly suggest the influence of positive Darwinian selection. The accessory gland protein gene (Acp26Aa) of Drosophila is one such example. In order to understand the mechanism of selection, it is often helpful to examine the pattern of polymorphism. We report here that the level of amino acid polymorphism in the N-terminal quarter of Acp26Aa is high in Drosophila melanogaster and is unprecedented in its sibling species Drosophila mauritiana. We postulate that (1) this N-terminal segment may play a role in sperm competition, and (2) D. mauritiana may have been under much more intense sexual selection than other species. Both postulates have important ramifications and deserve to be tested rigorously.

Differential coronary hemodynamics and left ventricular contractility in patients with syndrome X

The relationship between coronary hemodynamics and left ventricular contractility was studied in 20 patients with syndrome X. Among them, 10 patients with a resting left ventricular ejection fraction (LVEF, by radionuclide method) equal to or greater than the mean value of the whole group (58%) were defined as having relative increased left ventricular contractility (group H), and another 10 patients with relatively normal contractility (50%</=LVEF<58%) were in group N. Eight subjects with normal contractility, exercise test and coronary angiograms served as the control (group C). Baseline great cardiac venous flow (GCVF) was higher in group N than in group H (P<0.05) and C (P<0.05), but similar between group H and C. After dipyridamole infusion (0.56 mg/kg, i.v., for 4 min), maximum GCVF was less in group H than in group N (P<0.001) and C (P<0.001), but similar between group N and C. As compared to group C (3.09+/-0.35), coronary flow reserve was reduced in both group H (2.34+/-0.55, P=0. 004) and N (2.40+/-0.36, P=0.001). In all syndrome X patients, resting LVEF was negatively correlated to baseline GCVF (P=0.026) and tended to be positively correlated to baseline coronary vascular resistance (P=0.057). Thus, coronary hemodynamics was altered with left ventricular contractility in syndrome X patients. In these patients, coronary flow reserve was similarly reduced with different underlying mechanisms. The limited increase of GCVF after dipyridamole infusion suggests impaired coronary microvascular dilation capacity in patients with relatively increased left ventricular contractility and the increase of baseline GCVF in those with normal contractility is more likely due to an altered basal myocardial metabolism.

The phylogeny of closely related species as revealed by the genealogy of a speciation gene, Odysseus

Molecular differentiation between races or closely related species is often incongruent with the reproductive divergence of the taxa of interest. Shared ancient polymorphism and/or introgression during secondary contact may be responsible for the incongruence. At loci contributing to speciation, these two complications should be minimized (1, 2); hence, their variation may more faithfully reflect the history of the species' reproductive differentiation. In this study, we analyzed DNA polymorphism at the Odysseus (OdsH) locus of hybrid sterility between Drosophila mauritiana and Drosophila simulans and were able to verify such a prediction. Interestingly, DNA variation only a short distance away (1.8 kb) appears not to be influenced by the forces that shape the recent evolution of the OdsH coding region. This locus thus may represent a test case of inferring phylogeny of very closely related species.

Randomized, double-blind comparison of irbesartan and enalapril for treatment of mild to moderate hypertension

BACKGROUND

Irbesartan is a newly developed angiotensin II receptor antagonist. Its antihypertensive efficacy and safety in Taiwanese patients with mild to moderate hypertension remains to be determined.

METHODS

This was a multicenter, double-blind, randomized, parallel group study. One hundred and sixteen patients from three centers were enrolled. After a placebo lead-in period of 14 days, 55 patients (24-75 years-of-age) who had a mean seated diastolic blood pressure of 95 to 110 mmHg were randomized to once-daily treatment with irbesartan 150 mg or enalapril 10 mg. Doses were doubled at week 4 if trough seated diastolic blood pressure was 90 mmHg or more. Trough blood pressure was measured at zero, two, four and eight weeks of treatment.

RESULTS

Both treatments lowered blood pressure with no significant difference in efficacy between treatment groups. Irbesartan 150 mg to 300 mg provided reductions in trough seated systolic and diastolic blood pressures at week 8 of -16.5 mmHg and -7.2 mmHg, respectively, with 36% of patients having a favorable response. Similarly, enalapril 10 mg to 20 mg reduced systolic and diastolic blood pressure by -10.6 mmHg and -5.0 mmHg, respectively, with a response rate of 43%. Headache, malaise and dizziness were the major adverse reactions observed in both groups. The incidence of drug-related cough was significantly higher with enalapril (18%) than with irbesartan (0%).

CONCLUSIONS

Irbesartan 150 mg to 300 mg once daily was as effective in lowering blood pressure as enalapril 10 mg to 20 mg once daily. Both irbesartan and enalapril were well tolerated, while there was a significantly lower incidence of cough with irbesartan compared with enalapril.

Catheter-induced coronary spasm--a view of mechanical factors and experience with selective left coronary arteriography

BACKGROUND

Coronary spasm during cardiac catheterization is not unusual. The mechanism of spasm remains uncertain, but is considered to be multifactorial. Many researchers believe that coronary spasm that develops during catheterization is partly spontaneous and partly catheter-induced. Because catheter-induced spasm results from mechanical irritation, we tried to find the iatrogenic factors that predispose patients to coronary spasm during coronary angiography.

METHODS

Retrospectively, we reviewed the records of 7,295 patients who underwent coronary angiography at our hospital from June, 1983 to November, 1997; coronary spasm was documented in 30 patients, who became the study group. We randomly selected 41 patients who had normal coronary arteries as the normal control group. After reviewing cine films of coronary angiography, we compared these two groups for several parameters. These parameters included the length and diameter of the left main coronary artery (LMC), the angle between the LMC and the aorta, the angle between the catheter tip and the LMC, whether the catheter tip came into contact with the vascular wall and whether there was vessel wall bulging, catheter size and catheter/LMC ratio. This angiographic data and the demographic features, including age, sex, history of hypertension, diabetes mellitus, smoking, previous myocardial infarction, family history of coronary artery disease, cholesterol and triglyceride levels and chest pain character (exertional or rest pain) were compared between the study patient group and the control group.

RESULTS

The results disclosed that larger catheter size (7.1 +/- 0.6 mm vs 6.4 +/- 0.7 mm, p < 0.001), smaller LMC diameter (4.2 +/- 0.9 mm vs 4.9 +/- 1.0 mm, p = 0.004), larger catheter/LMC ratio (0.07 +/- 0.05 vs 0.05 +/- 0.03, p = 0.022), catheter contact with the vessel wall (27/30 vs 20/41, p < 0.001) and vessel bulging (18/30 vs 5/41, p < 0.001) were related to catheter-induced coronary spasm. We found that the catheter tip coming into contact with the vessel wall, vessel wall bulging and catheter/LMC ratio (odds ratio 8.92 x 10(14)) were statistically significant factors predisposing patients to catheter-induced coronary spasm.

CONCLUSIONS

Multiple factors contribute to coronary spasm. Of those, mechanical or iatrogenic factors might predispose patients to spasm during coronary catheterization. These facts deserve our attention, because iatrogenically induced spasms may be avoided by meticulously selecting catheters and manipulating them gently.

Significantly higher levels of oxidized LDL autoantibody in coronary artery disease patients

BACKGROUND

Increasing evidence shows that oxidized low-density lipoprotein (ox-LDL) might play an important role in the pathogenesis of atherosclerosis. Ox-LDL is immunogenic and induces an autoantibody, which we used as a tool for measuring the content of ox-LDL in vivo.

METHODS

Patients who were admitted for diagnostic cardiac catheterization for typical or atypical angina pectoris were enrolled in this study. After fasting for 12 hours, a venous blood sample was drawn from the antecubital vein for testing triglyceride, total cholesterol, LDL cholesterol, high-density lipoprotein (HDL) cholesterol, and ox-LDL autoantibody. The ox-LDL autoantibody was quantified using an enzyme linked immunosorbent assay. All patients underwent coronary angiography. Those who had more than 50% angiographic coronary luminal stenosis, were grouped into the coronary artery disease (CAD) group.

RESULTS

Sixty-four patients were enrolled in the study (male/female = 46/18; mean +/- standard deviation, age, 64 +/- 9 years). The CAD group had a significantly higher level of ox-LDL autoantibody than the non-CAD group (494.0 +/- 355.0 mU/ml vs 258.1 +/- 196.8 mU/ml, p = 0.004). However, the other lipid profiles including triglyceride, total cholesterol, LDL-cholesterol and HDL-cholesterol were not statistically different between the two groups. Forty-six patients in this study had an arterial blood sample taken from the femoral artery for testing ox-LDL autoantibody. There was no significant difference between the arterial and venous samples of ox-LDL autoantibody (385.2 +/- 333.3 mU/ml vs 399.3 +/- 339.5 mU/ml, n = 46, p = 0.530).

CONCLUSIONS

Ox-LDL autoantibody was significantly higher in the CAD group. Ox-LDL may prove to play a key role in the pathogenesis of atherosclerosis. Further study of Ox-LDL and its role in the process of atherosclerosis is warranted.

Insulin-like growth factor I improves cardiovascular function and suppresses apoptosis of cardiomyocytes in dilated cardiomyopathy

To investigate how insulin-like growth factor I (IGF-I) modulates cardiovascular function and myocardial apoptosis in heart failure, the therapeutic effects of IGF-I were determined in a canine model of dilated cardiomyopathy. The animals were paced at 220 beats/min, and the left ventricular (LV) chamber became dilated after 2 weeks. A subset of paced dogs was treated with s.c. injections of IGF-I from week 3 to week 4. After 4 weeks of pacing, untreated paced dogs developed significant ventricular dysfunction. IGF-I-treated paced dogs showed better cardiac output, stroke volume, LV end-systolic pressure, and LV end-diastolic pressure. Moreover, pulmonary wedge pressure and systemic vascular resistance were increased in the untreated group and decreased in the IGF-I-treated group. IGF-I treatment was associated with less thinning of the ventricular wall. Compared with the controls, untreated paced dogs showed increased apoptosis of cardiac muscle cells, which was partially suppressed by IGF-I treatment. The myocardial apoptotic index was negatively related to the thickness of the ventricular wall and to cardiac output, suggesting that ventricular remodeling/dysfunction involves the occurrence of myocardial apoptosis. Due to the close resemblance between this experimental model of dilated cardiomyopathy and human heart failure, the results of this study provide evidence that IGF-I may be a potential therapeutic agent for the failing human heart.

Coronary artery aneurysms: A 25-patient study

Coronary artery aneurysm is a rare disorder, characterized by abnormal dilatation of a localized portion or diffuse segments of the coronary artery. We studied clinical demographics, catheterization findings, and clinical outcomes in an Asian patient cohort with documented coronary artery aneurysms. Compared to a Caucasian adult population, our patient cohort had a lower incidence of coronary artery aneurysm (0.25% vs. 2.6%), and more patients with nonobstructive coronary artery aneurysms (70%); age, gender, and coronary distribution were comparable. The initial presentation of myocardial infarction occurred in five patients (5/17, 30%) with nonobstructive coronary artery aneurysms; however, none who were receiving preventive medications consisting of anticoagulant and antiplatelet agents subsequently developed myocardial infarction. We conclude that the incidence of coronary artery aneurysms with or without associated significant coronary stenosis seems to be lower in the Asian population. In contrast, the incidence of nonobstructive coronary artery aneurysms is considerably high and should not be thought of as a relatively benign disease entity if not treated with preventive medications. Rheumatoid arthritis-related vasculitis might be a cause of coronary artery aneurysm. Surgical intervention is based on the severity of coronary artery stenosis. The result of medical treatment has been compatible with long-term survival. Cathet. Cardiovasc. Intervent. 48:31-38, 1999.

Unilateral pulmonary artery agenesis with presentation of hemoptysis: a case report

Unilateral pulmonary artery agenesis (UPAA), a rare congenital anomaly frequently associated with other cardiovascular abnormalities, is usually diagnosed and surgically treated in childhood. Those who do not suffer other cardiac anomalies (isolated UPAA) have only minor or no symptoms and survive into adulthood. Isolated UPAA in adult patients may present as recurrent respiratory tract infection, dyspnea on exertion, hemoptysis or an incidental finding of an abnormal chest radiograph. We present the case of a 38-year-old man with a congenital absence of the right pulmonary artery (PA) and recurrent hemoptysis. The diagnosis was confirmed by cardiac catheterization, which disclosed an absence of the right PA and systemic collaterals to the right lung from the right internal thoracic artery and posterior intercostal arteries.

Evaluation of arterial compliance in patients with carotid arterial atherosclerosis

BACKGROUND

High-resolution peripheral vascular sonography has the capability to determine vessel compliance. A number of factors affect compliance in humans, including age, hypertension and atherosclerosis. However, compliance in patients with coronary artery disease (CAD) combined with carotid artery lesions has not been well studied. The objectives of this study were: 1) to determine whether carotid artery compliance is reduced in patients with CAD and carotid artery lesions, and 2) to determine whether decreased arterial compliance is related to an abnormality in vascular wall structure.

METHODS

The study participants included 12 patients with CAD and carotid artery disease (group III), 13 patients with CAD only (group II) and 13 age-matched normal subjects who served as controls (group I). High-resolution peripheral vascular ultrasonography was performed to directly visualize the common carotid artery and to measure its diameter and wall thickness. Carotid artery elastic properties were determined relative to arterial diameter and pressure generated within the heart.

RESULTS

Carotid artery walls were thicker in Group II and III patients than in normal subjects (1.49 +/- 0.03 mm, 1.98 +/- 0.04 mm, vs 1.22 +/- 0.03 mm, p < 0.05 and p < 0.01). There were significant differences in wall thickness between subgroups of CAD patients (p < 0.01). Carotid distensibility was lower (21.8 +/- 1.2 x 10(-6).N-1.m2, 14.8 +/- 1.7 x 10(-6).N-1.m2, vs 25.6 +/- 1.5 x 10(-6).N-1.m2; p < 0.05 and p < 0.01) and Young's modulus of elasticity was higher (3.12 +/- 0.43 x 10(5).Nm-2, 4.18 +/- 0.30 x 10(5).Nm-2, vs 2.34 +/- 0.23 x 10(5).Nm-2; p < 0.05 and p < 0.01) in group II and III patients than in normal subjects. These two indices of carotid artery compliance also differed between subgroups of CAD (p < 0.01). Increased wall thickness may occur secondary to changes in the architectural structure of the vessel wall, and these atherosclerotic changes lead to decreased compliance of arteries.

CONCLUSION

The mechanical properties of the carotid arteries provide reliable information regarding changes caused by atherosclerosis.

Differential coronary microvascular function in patients with left ventricular dysfunction of unknown cause--implication for possible mechanism of myocardial ischemia in early stage of cardiomyopathy

To evaluate whether or not coronary microvascular dysfunction is associated with exercise-induced myocardial ischemia in left ventricular dysfunction of unknown cause, both the treadmill exercise test (TET) and coronary hemodynamics were studied in 20 patients with impaired left ventricular ejection fraction (<50% by radionuclide ventriculogram), normal cardiac size, normal coronary angiogram and no evidence of clinical heart failure. Ten subjects with atypical chest pain were studied as the control. Coronary hemodynamics were studied both at baseline and after dipyridamole infusion (0.56mg/kg, i.v. for 4'). There was no difference in age, gender, blood pressure, baseline great cardiac venous flow (GCVF) and coronary vascular resistance between ten patients with a positive TET and the other ten with a negative TET. At baseline, coronary sinus oxygen concentration was increased and myocardial oxygen consumption reduced in patients with a positive TET compared with those with negative a TET. After dipyridamole infusion, maximum GCVF (102+/-47 vs. 144+/-31 ml/min, P=0.027) and coronary flow reserve (2.31+/-0.49 vs. 3.00+/-0.61, P=0.012) were significantly reduced and minimum coronary vascular resistance was higher (1.00+/-0.42 vs. 0.63+/-0.12 mmHg/ml/min, P=0.016) in patients with a positive TET than in those with a negative TET. At follow-up, 40% of patients with a positive TET and 10% of those with a negative TET developed clinical heart failure with a dilated left ventricle during a period of 45 months. Thus, coronary microvascular function is heterogeneous in patients with left ventricular dysfunction of unknown cause. In some of them, coronary microvascular dysfunction could be related to the presence of exercise-induced myocardial ischemia, suggesting that similar pathophysiology underlies the early stage of dilated cardiomyopathy and syndrome X.

Changes of the insulin-like growth factor I system during acute myocardial infarction: implications on left ventricular remodeling

In vitro and in vivo experiments have shown important biological actions of insulin-like growth factor I (IGF-I) in heart. The aims of this study were to determine the changes in circulating IGF-I and IGF-binding proteins (IGFBPs) during acute myocardial infarction (AMI) and to explore the relationship between IGF-I levels and myocardial remodeling and function after AMI. Thirty-four patients with acute Q-wave AMI and 17 matched controls were investigated in this study. Compared to normal subjects, free IGF-I and IGFBP-3 were significantly elevated, and IGFBP-1 was decreased upon AMI. Myocardial remodeling occurred after AMI in these patients. The day 2, 3, and 7 total IGF-I levels were inversely related to day 7 left ventricular (LV) end-diastolic, end-systolic diameters (r = -0.395 to -0.516) and LV mass (r = -0.487 to -0.661). Moreover, total IGF-I levels were positively related to LV ejection fraction (r = 0.402-0.453). Compared to the healthy survivors, those patients with poor outcomes had lower total IGF-I levels immediately after AMI. Most healthy survivors had total IGF-I levels greater than 137 ng/mL, but all patients with poor outcome had total IGF-I levels less than 137 ng/mL. Thus, AMI is associated with significant alterations in the IGF-I system. A higher total IGF-I level immediately after the onset of AMI is associated with better myocardial remodeling and ventricular function.

A rapidly evolving homeobox at the site of a hybrid sterility gene

The homeodomain is a DNA binding motif that is usually conserved among diverse taxa. Rapidly evolving homeodomains are thus of interest because their divergence may be associated with speciation. The exact site of the Odysseus (Ods) locus of hybrid male sterility in Drosophila contains such a homeobox gene. In the past half million years, this homeodomain has experienced more amino acid substitutions than it did in the preceding 700 million years; during this period, it has also evolved faster than other parts of the protein or even the introns. Such rapid sequence divergence is driven by positive selection and may contribute to reproductive isolation.

Parasympathetic withdrawal antedates dynamic myocardial ischemia in patients with syndrome X

This study was to evaluate the dynamic changes in cardiac autonomic control preceding electrocardiographic (ECG) myocardial ischemia in patients with syndrome X. Twenty-four-hour ambulatory ECG was obtained in 34 consecutive patients in a drug-free state. Fourteen (41%) of them, aged 58.8+/-13.5 years, presented a total of 19 ischemic episodes, mean duration 12.4+/-19.8 min (ranged 1 to 90 min). Heart rate variability was measured for 24 h; for 3 min and 30 min before, and during the 15 min (in five 3-min intervals) immediately antedating ST segment depression; and for another 3 min after ST segment back to normal. There were significant progressive shortenings in sinus cycle lengths over the 30 min preceding myocardial ischemia (-30 vs -3 minute, 822+/-32 ms vs 637+/-23 ins, P<0.05; a decrement of 22.5%). The sinus cycle lengths lengthened after ischemia ceased. High frequency activity, pNNSO and rMSS.D. were significantly reduced from the -30 min baseline to a nidus in the last 3 min before ischemia (P<0.05), whereas low frequency band and low/high frequency ratio did not present significant change. These findings strongly argue that cardiac autonomic control, especially vagal withdrawal, is involved in the pathogenesis of dynamic myocardial ischemia in syndrome X.

Differential glucose tolerance in dipper and nondipper essential hypertension: the implications of circadian blood pressure regulation on glucose tolerance in hypertension

OBJECTIVE

The goals of this study were to compare glucose tolerance in dipper and nondipper hypertensive patients and to explore the cause of glucose intolerance in essential hypertension.

RESEARCH DESIGN AND METHODS

A total of 50 patients <45 years old who had essential hypertension were recruited and studied by 24-h blood pressure monitoring and an oral glucose tolerance test (OGTT). Autonomic function was assessed with spectral analysis of heart rate variability

RESULTS

Dipper hypertensive patients (n=25) had lower nocturnal blood pressure than nondipper (n=25) patients. During OGTT, postprandial glucose levels were higher in the nondippers at 0, 90, and 120 min (all P < 0.05). Nondippers had a higher fasting insulin/glucose ratio than was apparent in normal control subjects. Despite higher postprandial glucose levels, nondippers had lower postprandial insulin levels. These results suggest that nondippers were insulin resistant and that their pancreatic beta-cell function was impaired. For all patients, nocturnal reduction of blood pressure was inversely related to total glucose levels under the OGTT curve and was positively related to postprandial insulin levels. Daytime heart rate did not differ between the dippers and nondippers, but nocturnal heart rate was higher in the nondippers, suggesting that nocturnal sympathetic activities were higher among the nondippers. Spectral analysis of heart rate variability suggests that the nondippers had lower parasympathetic activities and unbalanced sympathetic/parasympathetic outflow.

CONCLUSIONS

These findings indicate that nondipper hypertensive patients are more glucose intolerant than are dipper patients. The abnormalities of glucose metabolism in nondippers could be explained by insulin resistance and beta-cell dysfunction. The results of spectral analysis suggest that abnormal autonomic outflow may represent a possible link between hypertension and associated metabolic dysfunction.

Which arterial and cardiac parameters best predict left ventricular mass?

BACKGROUND

Many cardiovascular and noncardiovascular parameters are thought to be determinants of left ventricular mass (LVM). Complicated interactions necessitate the simultaneous measurement and consideration of each to determine their individual and collective impact on LVM. We undertook such a comprehensive study.

METHODS AND RESULTS

The influence of anthropometry, cardiac size and contractility, arterial structure and function, as well as indices of lifestyle, physical activity, and dietary salt intake on LVM (by two-dimensionally guided M-mode echocardiography) was analyzed in 1315 Chinese subjects who were either normotensive or had untreated hypertension. Effects of many cardiac and arterial factors were assessed. In univariate analysis, almost all measured noncardiovascular, cardiac, and arterial variables were significantly correlated with LVM. In multivariate linear regression analyses, when age, sex, body habitus, fasting serum C-peptide level, dietary salt, physical activity, and lifestyle were accounted for, the optimum multivariate linear regression main effects model had an adjusted model r2 of 0.740, with 98% of the model variance accounted for by the 5 independent determinants of LVM: stroke volume (49.6%), systolic blood pressure (30.7%), contractility (14.7%), body mass index (1.8%), and aortic root diameter (1.6%). Other proposed arterial indices were significant independent determinants of LVM only when blood pressure was removed from the model and, even then, these indices not only resulted in less powerful prediction but also accounted for only a very small percentage of the total variance of LVM.

CONCLUSIONS

In a large population, we (1) confirmed that age, body habitus, and some indexes of arterial structure and function are independent determinants of LVM; (2) found aortic diameter to be an independent structural determinant of LVM; (3) demonstrated that the effects of the derived measures of arterial function were small and provided no better predictive power than blood pressure alone; and (4) showed that when the best measures of cardiac and vascular load were included, the single most potent predictor was an index of left ventricular size.

Positive selection driving the evolution of a gene of male reproduction, Acp26Aa, of Drosophila: II. Divergence versus polymorphism

The evolution of the gene for a male ejaculatory protein, Acp26Aa, has been shown to be driven by positive selection when nonsibling species in the Drosophila melanogaster subgroup are compared. To know if selection has been operating in the recent past and to understand the details of its dynamics, we obtained DNA sequences of Acp26Aa and the nearby Acp26Ab gene from 39 D. melanogaster chromosomes. Together with the 10 published sequences, we analyzed 49 sequences from five populations in four continents. The southern African population is somewhat differentiated from all other populations, but its nucleotide diversity is lower at these two loci. We find the following results for Acp26Aa: (1) The R: S (replacement : silent changes) ratio is significantly higher in the between-species comparisons than in the within-species data by the McDonald and Kreitman test. Positive selection is probably responsible for the excess of amino acid replacements between species. (2) However, within-species nucleotide diversity is high. Neither the Tajima test nor the Fu and Li test indicates a reduction in nucleotide diversity due to positive selection in the recent past. (3) The newly derived nucleotides in D. melanogaster are at high frequency significantly more often than predicted by the neutral equilibrium. Since the nearby Acp26Ab gene does not show these patterns, these observations cannot be attributed to the characteristics of this chromosomal region. We suggest that positive selection is active, but may be weak, for each amino acid change in the Acp26Aa gene.

Prediction of right ventricular infarction from standard surface ECG in patients with inferior myocardial infarction

BACKGROUND

Patients with inferior myocardial infarction (MI) have a 45% chance of having concurrent right ventricular infarction (RVI); of these, 5-10% suffer hemodynamic collapse. Immediate correct diagnosis and appropriate management of such patients is vital. ST-segment elevation in the right precordial V4 lead (V4R) has a high diagnostic value in identifying RVI, but this determination requires additional time and cost. An attempt was made to use a collection of patients' standard surface electrocardiograms (ECG) to find any available data to detect RVI and to lead to a new way to diagnose RVI.

METHODS

Fifty patients (males/females, 44/6; mean age, 64.3 +/- 6.9 years) with acute inferior myocardial infarction were enrolled in a first group to develop new diagnostic criteria for RVI. As a first step, the ST-segment change in every standard surface ECG lead was analyzed and compared with corresponding changes in V4R. RVI was diagnosed by typical clinical symptoms (chest pain for more than 30 minutes, ST elevation > 0.1 mV and enzyme changes) accompanying ST elevation of more than 0.1 mV in V4R (by Lopez-Sendon criteria) and echocardiographic findings. RVI was diagnosed in 24 (48%) patients using ECG. The new criteria were then tested in a secondary group of 48 patients (males/females, 43/5; mean age, 65.5 +/- 7.9 years) with inferior MI.

RESULTS

Analysis of these patients found that ST depression in lead I and aVL was a specific characteristic of RVI (I + aVL > 0.2 mV). This criterion was applied to another group of patients with acute inferior MI to check the predictive value (sensitivity, 94.7%; specificity, 89.7%; positive predictive value, 85.7%; negative predictive value, 96.3%).

CONCLUSIONS

In patients with evolving inferior MI, standard surface ECG analyzed for this criterion could aid clinical recognition of concomitant RVI.

Dopamine and dobutamine have different effects on heart rate variability in patients with congestive heart failure

BACKGROUND

Autonomic dysfunction plays an important role in the pathogenesis, treatment and prognosis of congestive heart failure (CHF). Sympathomimetic amines have been widely used in the treatment of CHF, but reports on their autonomic effects in CHF are rare. This study was designed to evaluate the effects of dopamine and dobutamine on cardiac autonomic function as assessed by heart rate variability (HRV).

METHODS

Twenty patients with symptomatic CHF (systolic dysfunction) were enrolled. After recording one-hour baseline electrocardiographs (ECGs), patients were randomly selected for either dopamine (4 micrograms/kg/minute, Group A) or dobutamine (4 micrograms/kg/minute, Group B) treatment for three days. On the third day, a 24-hour ambulatory ECG was recorded and a tilt-table test was performed. Only furosemide and nitrates were allowed for adjunctive therapy. HRV was measured before and after treatment in both time and frequency domains. Frequency-domain HRV was also measured during head-up tilt.

RESULTS

After treatment, all patients improved [New York Heart Association fraction (NYHA Fc) 3.7 to 2.0]. Group A patients had higher post-treatment 24-hour HRV than those in Group B. SDNN (standard deviation of the average normal RR intervals in the entire ECG recording), SDANN (standard deviation of the average normal RR intervals for all five minute segments of an entire ECG recording) and SDNN indices in Group A were significantly higher than in Group B (90 +/- 33 ms vs 41 +/- 12 ms, 78 +/- 32 ms vs 36 +/- 11 ms, and 37 +/- 19 ms vs 16 +/- 7 ms, respectively, all p < 0.05). rMSSD (the square root of the mean of the squared differences between adjacent normal RR intervals over the entire ECG recording) and pNN50 (percentage of differences between adjacent normal RR intervals that are greater than 50 ms computed over the entire ECG recording) were also higher in Group A patients, with borderline significance. All measurements of total frequency and low-frequency and high-frequency components tended to be higher in Group A than Group B, but this was only significant for total frequency amplitude (22.9 +/- 13.4 ms vs 10.9 +/- 6.1 ms, p < 0.05). Dopamine but not dobutamine treatment seems to restore the depressed circadian change in frequency-domain HRV classically seen in patients with CHF. The HRV change during head-up tilting did not differ between the two groups. Three patients in Group B showed non-sustained ventricular tachycardia on ambulatory ECG during the treatment period.

CONCLUSIONS

Dopamine and dobutamine have comparable therapeutic effects in patients with CHF, but low-dose dopamine more favorably affects cardiac autonomic function.

Incipient speciation by sexual isolation in Drosophila melanogaster: extensive genetic divergence without reinforcement

The collection of Drosophila melanogaster from Zimbabwe and nearby regions (the Z-type) yield females who would not mate with the cosmopolitan D. melanogaster males (the M-type). To dissect the genetic basis of this sexual isolation, we constructed 16 whole-chromosome substitution lines between two standard Z- and M-lines. The results were as follows: (1) All substitution lines appear normal in viability and fertility in both sexes, indicating no strong postmating isolation. (2) The genes for the behaviors are mapped to all three major chromosomes with the same ranking and comparable magnitude of effects for both sexes: III > II >> X > or = 0 (III, II and X designate the effects of the three chromosomes). The results suggest less evolution on the X than on autosomes at loci of sexual behavior. (3) The genes for "Z-maleness" are many and somewhat redundant. Whole-chromosome effects for Z-maleness appear nearly additive and show little dominance. (4) In contrast, "Z-femaleness" has less redundancy as partial genotypes never exhibit full phenotypic effects. Epistatic interactions and incomplete dominance can sometimes be detected. (5) The extensive genetic divergence underlying sexual isolation has evolved in the absence of detectable reduction in hybrid fitnesses. Sexual selection has apparently been a driving force of multiple facets of speciation at the nascent stage without reinforcement.

Congenital sinus of Valsalva aneurysm: a multiplane transesophageal echocardiographic experience

Sinus of Valsalva aneurysm is a rare congenital anomaly which, if overlooked, may be associated with increased mortality and morbidity. Multiplane transesophageal echocardiography proved useful in identifying a variety of associated structural heart disease. This study sought to assess the accuracy of the surgical result on the basis of the multiplane transesophageal echocardiography findings and to describe patient demographics and clinical outcome in an Oriental patient cohort. From July 1984 to December 1995, clinical, catheterization, echocardiographic, and surgical results were retrospectively studied in 23 patients with documented sinus of Valsalva aneurysm. Compared with previous reports of Oriental patients, our patient cohort was older (p < 0.025), had more associated aortic, mitral, and tricuspid regurgitation (p < 0.01), but had fewer coexistent ventricular septal defects (p < 0.01), and had more associated coronary artery disease (9%). Multiplane transesophageal echocardiography precisely showed three undiagnosed and/or ambiguous transthoracic echocardiographic studies, and the preoperative transesophageal echocardiography TEE findings were confirmed intraoperatively in the last eight consecutive patients. We concluded that multiplane transesophageal echocardiography provides conclusive information and is the current technique of choice for diagnosis and clinical management of patients with sinus of Valsalva aneurysm; although the natural history of sinus of Valsalva aneurysm remains uncertain, it is likely that the incidence of unruptured sinus of Valsalva aneurysm is considerably higher in the elderly than has been previously reported.

Syndrome X: pathophysiology and clinical management

The term "syndrome X" is now widely used to specify a group of patients with anginal chest pain, ischemia-like electrocardiogram, normal coronary angiograms, and no evidence of coronary spasm. Though chest pain and exercise-induced myocardial ischemia may both be present in patients with syndrome X and those with coronary artery disease, the underlying pathogenesis of these two disease entities is different. In patients with syndrome X, the causes of angina and myocardial ischemia are multifarious while coronary angiograms are normal. Coronary microvascular function has been shown to be impaired in these patients. However, the presentation of myocardial ischemia may be varied and even subclinical, suggesting dynamic characteristics and regional distribution of coronary microvascular insufficiency in them. Recently, there is increasing evidence that chest pain may develop without detectable myocardial ischemia and has been attributed to abnormal pain perception in at least some of the patients. Thus, there is a heterogeneous group of patients with syndrome X. The rational patient management should be related to individual clinical presentation and depend upon the proper identification of the underlying mechanisms of anginal chest pain or myocardial ischemia or both in these patients.

Histamine 2 receptor blocker-ranitidine and sinus node dysfunction

BACKGROUND

Histamine 2 (H2) receptors were observed to be present in the sinus node. H2 receptor blockers could attenuate the histamine-induced increase in sinus rate and could thereby worsen sinus node dysfunction. However, the data pertaining to electrophysiological effects of H2 receptor blocker ranitidine on sinus node function are not available as yet, although bradycardia has been occasionally reported along with ranitidine. The present study evaluates the electrophysiological effects of ranitidine on sinus node function, and also determines the safety of administering ranitidine to patients suffering from sinus node dysfunction.

METHODS

Thirty-nine patients with clinical diagnosis of sinus node dysfunction were selected for this study. Electrophysiological effects of intravenous injection of 150 mg ranitidine on sinus node function was evaluated. Tests were performed for 21 patients in the basal state (Group 1) and for 18 patients (Group 2) after autonomic blockade (propranolol 0.2 mg/kg, and atropine 0.04 mg/kg). The sinus cycle length (SCL), sinus node recovery time (SNRT), corrected sinus node recovery time (CSNRT), sinoatrial conduction time (SACT), atrio-His (AH) and His-ventricle (HV) intervals and blood pressure (BP) before and after ranitidine were analyzed.

RESULTS

In Group 1, changes in SCL, SNRT, CSNRT, SACT, AH, HV and BP were not found to be significant. However, in Group 2, wherein the patients received ranitidine after autonomic blockade, it was observed that ranitidine significantly prolonged SCL (905.0 +/- 31.0 to 1000.0 +/- 40.0 msec, p = 0.001), decreased systolic BP (134.7 +/- 4.7 to 124.8 +/- 4.8 mmHg, p < 0.001), and diastolic BP (71.9 +/- 2.0 to 67.9 +/- 1.9 mmHg, p = 0.001), while the changes in SNRT, CSNRT, SACT, AH and HV were not significant.

CONCLUSIONS

A clinical dose of 150 mg ranitidine must be administered by a slow intravenous infusion for at least 5 minutes in case of patients suffering from sinus node dysfunction. Continuous monitoring of BP and heart rate are necessary, especially in cases of autonomic denervation.

Effects of short-term treatment of nicorandil on exercise-induced myocardial ischemia and abnormal cardiac autonomic activity in microvascular angina

The underlying mechanisms of myocardial ischemia in microvascular angina may include endothelial dysfunction, abnormal smooth muscle tone, and abnormal autonomic control of coronary microvasculatures. This randomized, double-blind, placebo-controlled, crossover study was conducted to evaluate the effect of nicorandil (a nitrate-potassium channel opener) therapy on exercise-induced myocardial ischemia and cardiac autonomic activity in 13 patients with microvascular angina. After a 2-week placebo run-in period, patients were randomly assigned to the first 2-week treatment with nicorandil 5 mg tid or placebo, then crossed over to the second 2-week treatment after a 2-week washout period. Treadmill exercise tests and 24-hour ambulatory electrocardiogram monitoring were performed at the end of each treatment phase. The results showed that both time to 1-mm ST depression and total exercise duration were significantly prolonged with nicorandil treatment compared with placebo (p = 0.026 and 0.036, respectively). Maximum exercise ST depression also tended to be less with nicorandil treatment than with placebo (p = 0.083). Compared with 10 healthy control subjects, study patients had significantly reduced heart rate variability in both low- and high-frequency bands while receiving placebo. Nicorandil treatment did not change the altered heart rate variability in either time domain or spectral analysis. Systemic hemodynamics were also unchanged with nicorandil treatment. Thus, 2-week oral nicorandil therapy moderately improved exercise-induced myocardial ischemia without modifying the already altered cardiac autonomic activity, suggesting that nicorandil might have a direct vasodilatory effect on coronary microvasculatures in patients with microvascular angina.

The effect of thrombolytic therapy on short- and long-term cardiac autonomic activity in patients with acute myocardial infarction

BACKGROUND

Reduced heart rate variability after acute myocardial infarction is an important risk stratification factor for mortality and life threatening ventricular arrhythmias. In recent years, thrombolytic therapy has revolutionized the therapy of acute myocardial infarction. However, there is little information about the mechanism of the beneficial effect of thrombolysis on cardiovascular mortality. This study was launched to investigate the relationship between thrombolytic therapy and cardiac autonomic activity, and the sequential changes in heart rate variability after acute myocardial infarction.

METHODS

From October 1994 to July 1995, all consecutive patients with their first acute myocardial infarction were prospectively enrolled into the study. Patients without contraindication underwent thrombolytic therapy within six hours of the onset of symptoms. Other patients received conventional treatment. Ambulatory electrocardiography (EKG) was recorded on each patient 7, 90 and 180 days after acute myocardial infarction. Heart rate variability in time- and frequency-domain was analyzed.

RESULTS

A total of 49 patients, 45 males and 4 females, were included in this study. The short-term heart rate variability (HRV) (seven-day) in the thrombolytic group was significantly higher than in the nonthrombolytic group in SDANN and SDNN. No significant difference in rMSSD, pNN50, LF, HF or LF/HF ratio was found. The location of MI did not influence the short-term HRV following acute myocardial infarction. In patients treated with thrombolytic agent, the follow-up HRV at 90 days and 180 days increased significantly compared to the baseline HRV (seven-day) in SDANN, SDNN, LF and HF bands. For patients without thrombolytic therapy, their follow-up HRV at 90-day and 180-day increased significantly as compared to the baseline HRV (seven-day) in SDANN and SDNN only. After correction of ventricular ejection fraction, the higher short-term (seven day) HRV activities were still present in SDANN and SDNN in patients with thrombolysis as compared to those without. The 90-day and 180-day HRV did not differ between patients with and without thrombolytic agent. Three patients died suddenly during follow-up, and all showed significantly lower values of HRV than the survivors.

CONCLUSIONS

The findings of the present study suggest that 1) in patients with uncomplicated AMI, HRV was transiently reduced with progressive improvement within three months after AMI in both those with and without thrombolytic therapy, and 2) patients who had received thrombolytic treatment had more improved HRV early (seven days) after AMI than those who did not. This improvement, independent of the change of left ventricular function, could be associated with the beneficial effect of thrombolytic therapy in patients with AMI.

Coronary microvascular dysfunction is associated with ischemic-like electrocardiogram during exercise in patients with anginal chest pain and normal coronary angiograms

To determine the possible mechanism of the ischemic-like electrocardiogram (ECG) during exercise in the presence of anginal chest pain and normal coronary angiograms, both a treadmill exercise test (TET) and coronary hemodynamic study were prospectively performed in 33 consecutive patients (18 females and 15 males, aged 48 +/- 10 years) with angina of unknown cause. Although baseline characteristics and coronary hemodynamics were similar between patients with (TET+, n = 17) and those without (TET-, n = 16) ischemic-like ECG during TET, effort angina was more frequently seen in the former group (p < 0.01). Compared to TET- patients, TET+ patients had a significantly lower maximum great cardiac vein flow (GCVF, 108.8 +/- 47.0 vs 146.4 +/- 23.4 ml/min, p = 0.007), higher minimum coronary vascular resistance (0.94 +/- 0.41 vs 0.61 +/- 0.09 mmHg/ml/min., p = 0.003), and lower corrected GCVF (GCVF/rate-pressure product, 0.0087 +/- 0.0036 vs 0.0125 +/- 0.0019, p = 0.001) after dipyridamole infusion (0.56 mg/kg for 4 min). Though coronary flow reserve was significantly lower in TET+ than in TET- patients (2.26 +/- 0.59 vs 3.08 +/- 0.48, p = 0.0001), myocardial oxygen consumption and myocardial efficiency (rate-pressure product/myocardial oxygen consumption) were still similar between these two groups after dipyridamole infusion. Thus, coronary microvascular dysfunction rather than altered cardiac metabolism could contribute to effort angina and ischemic-like ECG during exercise in patients with anginal chest pain and normal coronary angiograms.

Effect of quinapril therapy on blood pressure and serotonin change in patients with mild to moderate hypertension

BACKGROUND

Previous studies have shown that serotonin plays an important role in hypertension because of its vasoconstrictive effect, mediated through serotonergic receptors. Angiotensin-II is a potent vasopressor which facilitates the aggregation of platelets, subsequently releases serotonin. Because quinapril is an angiotensin-converting enzyme inhibitor and could result in a decrease of angiotensin-II, Quinapril was used to treat patients with mild or moderate hypertension in order to observe the change of plasma serotonin.

METHODS

Twenty-two patients, (10 males, 12 females, mean age 45 yrs) without other major medical diseases and secondary causes of hypertension, were selected for this study. High performance liquid chromatography (HPLC) with electrochemical detection was used to detect the plasma serotonin. These patients were given placebos for two weeks before the first dose of quinapril (5 mg). Thereafter, the dosage was adjusted according to the response of blood pressure to a desired value (BP < 140/90 mmHg). At about 14:00 hours on the first day, after the patient had rested for an hour and was in a quiet condition, blood was drawn by venipuncture with heparin as anti coagulant; the plasma serotonin concentration was determined for the baseline value. The plasma serotonin level was rechecked eight weeks later.

RESULTS

It was found that systolic blood pressure began to decrease significantly two weeks after quinapril therapy, and then reached a constant state. Blood pressure decreased from 174/107 mmHg to 134/87 mmHg. Among these 22 patients, there were 14 (65%) whose blood pressure reduced to a normal range. Plasma serotonin also decreased significantly from 4.69 +/- /3.67 ng/ ml to 2.89 +/-2.64 ng/ml (p < 0.05). According to this data, 15 in 22 patients (68%) had reduction of plasma serotonin. There was little correlation between change in blood pressure and change of plasma serotonin; the correlation co-efficiency is only 0.019.

CONCLUSIONS

This study shows that quinapril has an antihypertensive property and serotonin-lowering effect. Since there was no correlation between the change of serotonin and blood pressure, these two actions of quinapril might have been mediated through different mechanisms.

Changes in cardiac autonomic activities in patients with syndrome X. A study of spectral analysis of heart rate variability

The present study was designed to assess cardiac autonomic activities, coronary microvascular function, and their relationship in patients with syndrome X. Control of coronary blood flow is complex, and impaired coronary flow reserve has been attributed as the cause of myocardial ischemia in patients with syndrome X. It is unknown whether cardiac autonomic activities are altered in the presence of coronary microvascular dysfunction in patients with syndrome X. Eighteen patients with syndrome X were studied. Great cardiac vein flow was measured by the thermodilution method and the coronary flow reserve was determined by intravenous dipyridamole (0.56 mg/kg) infusion. Twenty-four-hour ambulatory electrocardiograms were obtained in a drug-free state. Another 14 age- and sex-matched normal subjects served as a control group. The amplitude (in ms) of ultralow (ULF), very-low (VLF), low (LF), and high (HF) frequency bands and total spectra of heart rate variability were measured for twenty-four-hour and every four-hour interval of the day.

'Reverse redistribution pattern' during myocardial perfusion imaging with 99Tcm-MIBI

We retrospectively studied 540 consecutive patients with coronary artery disease (CAD) undergoing 99Tcm-methoxy-isobutyl-isonitrile (99Tcm-MIBI) myocardial single photon emission tomography (SPET) to determine the incidence of the 'reverse redistribution pattern' (RRP). RRP is similar to reverse redistribution (RR) in 201Tl myocardial SPET and is defined as the presence of a perfusion defect on the resting cardiac image, rather than on the exercise image. Our results confirmed 30 (5.6%) patients to have RRP, all of whom underwent diagnostic coronary angiography. None of the 30 patients showed RRP in the territory of the left circumflex coronary artery. RRP occurred in the territory of the left anterior descending coronary artery (LAD) in 16 patients, 12 of whom had a normal LAD. Fourteen patients presented with RRP in the territory of the right coronary artery, all of whom had normal coronary arteries. RRP in 99Tcm-MIBI myocardial SPET is less common than RR in 201Tl myocardial SPET and is frequently associated with normal coronary arteries. RRP with 99Tc(m)-MIBI seems to be of little value in the diagnosis of CAD.

Evidence of genetic heterogeneity of hypertrophic cardiomyopathy in eight Chinese patients

BACKGROUND

The genetic basis causing hypertrophic cardiomyopathy (HCM) was found due to missense mutations in cardiac beta-myosin heavy chain (beta-MHC), cardiac troponin T and alpha-tropomyosin genes in certain affected families. However, most mutations and majority of the affected families were reported to be related to beta-MHC gene. Till now, 20 different missense mutations of beta-MHC gene identified in more than 40 independent families were distributed in exons 8, 9, 13, 14, 15, 16, 19, 20, 21 and 23. Therefore, we chose these 10 exons for screening.

METHODS

Eight probands with HCM and 1 normal control were included for screening. 32P-labeled PCR products of these 10 exons of beta-MHC gene were amplified from genomic DNA obtained from peripheral lymphocytes. PCR-DNA single strand conformation polymorphism (PCR-SSCP) analysis was performed using electrophoresis with polyacrylamide gels with and without 10% glycerol. Large amount copies of these 10 exons were also made from genomic DNA with PCR. Detection of sequencing variation of these exons was determined by the direct sequencing method with dideoxy chain termination method and 35S.

RESULTS

No abnormal extra bands were noted on PCR-SSCP analysis. Sequencing analysis showed no missense mutation in these probands.

CONCLUSIONS

Genetic heterogeneity of HCM is evident in Chinese patients with HCM.