Catheter ablation for ventricular tachycardia

Sudden cardiac death due to ventricular arrhythmias remains the most common cause of death in developed nations. Implantable cardioverter defibrillators have been shown to improve mortality in high-risk groups for ventricular tachyarrhythmias, but they are not curative, with the risk of arrhythmia recurrence remaining unaltered. It is also important to remember that ventricular tachycardia (VT) in the setting of a structurally normal heart is often not associated with an increased risk of sudden death and catheter ablation is a potentially curative procedure in this cohort. Recent advances in catheter ablation for VT have increased the efficacy in creating adequate lesions, accurate three-dimensional maps and mapping haemodynamically unstable VT, all of which have increased the utility of this modality in the treatment of ventricular arrhythmias. In this article, we review the recent advances that have fuelled renewed interest in catheter ablation of VT, its clinical utility and who should be referred.

CFD modelling of flow field and particle tracking in a hydrodynamic stormwater separator

The best management practices (BMPs) for control of urban stormwater pollution are evaluated to remove solid particles containing various pollutants. Currently, most storm runoff treatment devices using primary pollutant removal mechanism are applied to storm water since most pollutants in runoff are associated with the solid particulates. A hydrodynamic separator is a storm water treatment device using centrifugal motion which separates solids pollution from runoff. In this study, the velocity flow field and particle tracking of hydrodynamic separator were investigated using anthracite as a computational fluid dynamics (CFD) model particle. The Fluent 6.3.26 CFD program was used to predict the solid particles removal efficiency for various parameters such as particle size, surface loading rate, and the ratio of underflow to overflow. The velocity flow field in a hydrodynamic stormwater separator (HDS) has been simulated using CFD RNG κ-ε model. Modeling results for the removal efficiency of HDS were similar with the results obtained from experimental measurements of laboratory scale HDS. These results showed that the simulated velocity field was useful to interpret the behavior of flow in the hydrodynamic separator. The results obtained from particle tracking can be applied to predict the separation efficiency.

A standard panel of microsatellites for Asian seabass (Lates calcarifer)

Microsatellites are the most popular markers for parentage assignment and population genetic studies. To meet the demand for international comparability for genetic studies of Asian seabass, a standard panel of 28 microsatellites has been selected and characterized using the DNA of 24 individuals from Thailand, Malaysia, Indonesia and Australia. The average allele number of these markers was 10.82 +/- 0.71 (range: 6-19), and the expected heterozygosity averaged 0.76 +/- 0.02 (range: 0.63-1.00). All microsatellites showed Mendelian inheritance. In addition, eight standard size controls have been developed by cloning a set of microsatellite alleles into a pGEM-T vector to calibrate allele sizes determined by different laboratories, and are available upon request. Seven multiplex PCRs, each amplifying 3-5 markers, were optimized to accurately and rapidly genotype microsatellites. Parentage assignment using 10 microsatellites in two crosses (10 x 10 and 20 x 20) demonstrated a high power of these markers for revealing parent-sibling connections. This standard set of microsatellites will standardize genetic diversity studies of Asian seabass, and the multiplex PCR sets will facilitate parentage assignment.

Pharmacokinetic and pharmacogenetic study of S-1 in Korean patients with metastatic biliary cancer

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Background: S-1 is an oral anticancer agent composed of tegafur (FT), CDHP, and oxonate. CYP2A6 is related to the biotransformation of FT to 5-FU. We evaluated associations of genetic variants of CYP2A6 with PK/PD of S-1 when combined with oxaliplatin in metastatic biliary cancer. Methods: This is a prospective study of patients with histologically confirmed metastatic adenocarcinoma of the biliary tract. S-1 was administered orally at a dose of 40 mg/m2 twice daily for 14 days followed by a 7-day rest period. For PK study, S-1 was given only once at day 1 of cycle 1. From day 2, it was administered twice daily. Oxaliplatin was administered intravenously at a dose of 130 mg/m2 for 2 hours every 3 weeks. CYP2A6 polymorphism (*1, *4, *7, *9 or *10) were genotyped. Results: A total of 49 patients were enrolled. Median age was 52 years (range 23–68) and male accounted for 63%. Thirty patients (61%) had intrahepatic cholangiocarcinoma and 10 (20%) gallbladder cancer. Response rate was observed in 24.5%. The median PFS and OS were 3.7 months and 8.7 months . Grade 3–4 adverse events include vomiting (22%), diarrhea (4%) and neutropenia (14%). The allele frequencies of CYP2A6*4, *7, *9 and *10 were 10.2%, 8.2%, 19.4%, and 4.1%, respectively. AUC0–24hr of 5-FU was 1030±617.3 hr*ng/mL (range 249.5–3969, CV: 59.9%). Log- transformed AUC0–24hr were significantly different for FT and 5-FU in the *1/*1 group; metabolic ratio (AUC0- 24hr of 5-FU/AUC0–24hr of FT) of the *1/*1 group was 1.85-times higher than the other group (90% CI 1.37–2.49). AUC0–24hr of CDHP was not significantly associated with CYP2A6 genotype. Despite differences in exposure, CYP2A6 genotypes were not significantly associated with diarrhea (P=0.0740), neutropenia (P=0.396) and clinical efficacy (response rate: P=0.583, PFS: P=0.916). Conclusions: CYP2A6 genotypes was associated with transformation of FT to 5-FU; however, this association did not translate into different clinical efficacy or toxicity.

[Table: see text]

No significant financial relationships to disclose.

Ethnic differences in myocardial infarction in patients with hypertension: effects of diabetes mellitus

BACKGROUND

It has been reported that hypertension carries a greater risk of myocardial infarction (MI) in South Asians living in the UK than in the indigenous British population. This has been attributed to some specifically Asian susceptibility factor.

DESIGN

Using a longitudinal approach, we investigated the relationship between coronary heart disease (CHD) risk factors amongst hypertension patients attending Sandwell and City Hospitals, and the onset of cardiovascular events over a 5-year follow-up period.

RESULTS

A total of 350 Caucasian (83.7% male) and 104 South Asian (66.3% male) patients with hypertension [age 63.7 (7.6) years and 57.1 (11.1) years respectively, P < 0.001] were followed-up for a mean (SD) period of 64.7(12.1) months. There were 11 (6.4/1000 patient years) cases of MI in Caucasian patients vs. 11 (17.8/1000 patient years) in South Asians, with event-free survival times being significantly lower amongst South Asians (log-rank test P = 0.04). The prevalence of diabetes mellitus was 22.9% higher amongst South Asians (P < 0.001), whilst mean serum cholesterol and fasting triglyceride levels were higher amongst Caucasians (P = 0.001). There were no ethnic differences in HDL cholesterol concentrations, the use of tobacco, statin therapy or anti-platelet therapies (all P = NS), or in composite endpoint (MI, angina, peripheral vascular disease, stroke, revascularization or death; P = 0.74). On Cox regression analysis of all independent cardiovascular risk variables, associated treatments and ethnicity, MI risk was associated with diabetes mellitus (odds ratio 3.77, 95%CI 1.55-9.15, P = 0.003) but not ethnicity per se (P = 0.26).

CONCLUSION

Increased risk of MI in hypertensive South Asians in the United Kingdom appears to be the result of a higher prevalence of diabetes mellitus. Further work is required to understand the pathophysiological basis with which diabetes increases CHD risk in this ethnic group.

CYP2A6 genetic polymorphism as a predictive marker for clinical outcomes in patients (pts) with metastastic gastric carcinoma (MGC) treated with S-1 plus docetaxel

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CYP2A6 genetic polymorphism as a predictive marker for clinical outcomes in patients (pts) with metastastic gastric carcinoma (MGC) treated with S-1 plus docetaxel Background: Tegafur, a component of S-1, a novel oral fluoropyrimidine, is converted to 5-fluorouracil via CYP2A6. An allelic variant of CYP2A6, -48T>G (CYP26A*9) encodes an enzyme with reduced activity. We investigated the association between the polymorphism of CYP2A6*9 and treatment outcomes in Korean pts with MGC who received S-1 plus docetaxel. Methods: From Oct 2005 to July 2006, 50 pts with MGC were enrolled for a phase II study of first line chemotherapy with S-1 and docetaxel. Treatment consisted of oral S-1 40 mg/m2 bid on days 1–14, and i.v. docetaxel 35 mg/m2 on days 1, 8, every 3 weeks. Genotypes were determined with single base extension method for CYP26A*9 from genomic DNA extracted from the peripheral blood samples. Results: The median age was 53 years (range, 23–70) with the median PS of 1 (range, 0–2). The frequency of wild type allele (w/w) was 34 (68%), heterozygous (*9/w), 12 (24%), and homozygous (*9/*9), 4 (8%). The response rate was 25.0% in homozygous pts, 50.0% in heterozygous and 76.5% in wild type (p=0.03, Fisher’s exact test). The median time to progression at a median follow-up of 9.8 months (mo) was shorter in homozygous pts (3.9 mo; 95% CI, 0.4–7.4) as compared to heterozygous and wild types (6.9 mo; 95% CI, 6.0–7.8) (p=0.11). Although the median overall survival did not reach in 4 homozygous pts, it was 13.5 mo (95% CI, 8.3–18.7) in heterozygous and wild type. The frequencies of grade (G) 3/4 toxicities were lower in homozygous pts than the others without statistical significance. Conclusions: The data suggest that CYP2A6*9 polymorphism might be a predictive marker for efficacy and toxicity of S-1 based chemotherapy in MGC pts. Further studies involving more pts are needed to confirm the results. (Supported by NCC Grant 0610520)

[Table: see text]

No significant financial relationships to disclose.

Aromatase inhibitors (AIs) with or without GnRH agonist as first-line hormone therapy in pre- and post-menopausal Korean women with metastatic breast cancer (MBC): Clinical outcomes in correlation with tumor ER/PR/HER2 status

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Background: Clinical outcomes of patients (pts) with MBC by AIs in comprehensive relationship with ER/PR/HER2 status have been scant that the study was performed to analyze their predictive values singly and in combination. Methods: 111 pts who took letrozole or anastrozole as first-line hormonal therapy for MBC were identified from the database at NCC Hospital between Nov. 2001 and Aug. 2005. Pts on AIs concomitantly with or immediately followed by chemotherapy were excluded. AIs/GnRH agonists were used when hormonal levels were not postmenopausal. ER/PR were scored strong, intermediate or weak. HER2+ was IHC 3+ or FISH+. HER2− was IHC 0, 1+ or 2+/FISH−. Clinical benefit (CB) included CR/PR/improving or SD ≥6 months. Results: Median age was 54 years (range, 29–78). Overall 66% achieved CB (CR/PR 18%, improving 26%, and SD ≥ 6mo 22%) with median TTP, 9 mo (range, 1–50, 95% CI, 7–11), and median survival, 41 mo (range, 2–50). Age, AIs with (20) vs. without (91) GnRH agonist, DFI ≤ vs. > 24 mo, adjuvant tamoxifen, or prior metastatic chemotherapy did not affect clinical outcomes. Disease sites (%) were bone (64), LN (52), lung/pleura (41), liver (25), breast (20) and skin (7). Bone only disease had longer TTP (p = 0.004), while liver involvement was associated with short TTP (p = 0.0001)/OS (p = 0.007). ER was 56% strong +, 21% intermediate +, 15% weak +, 5% - and 3% unknown, PR: 24% strong +, 23% intermediate +, 24% weak +, 23% -, and 5% unknown, and HER2: 23% +, 67% -, and 10% unknown. Staining intensity did not affect CB in ER+ tumors. More CB (p = 0.002)/longer TTP (p = 0.003) with strong/intermediate PR+ tumors vs. weak PR+/PR− tumors, and more CB with ER+/PR+ tumors vs. ER+/PR− tumors (P = 0.016) were observed. More CB with HER2− tumors vs. HER2+ tumors (p = 0.001), and with PR+/HER2− tumors vs. the rest (PR−/HER−, PR+/HER+, PR−/HER+) (p = 0.0007) were seen. HER2 positivity was associated with less CB (p = 0.0004)/shorter TTP (p = 0.0157) in ER+/PR+ tumors vs. no influence on CB (p = 0.245)/TTP (p = 0.52) in ER+/PR− tumors. Conclusions: AIs with or without GnRH agonist are effective therapy for pts with MBC, specifically with ER+/PR+/HER2− tumors regardless of ages.

No significant financial relationships to disclose.

Clinically apparent atherosclerotic disease in diabetes is associated with an increase in platelet microparticle levels

BACKGROUND

The commonest cause of mortality in patients with Type 2 diabetes is atherothrombosis, which can be related to abnormalities in the coagulation and fibrinolytic pathways, as well as in platelet function. Platelet microparticles (PMPs) may contribute to the prothrombotic state and may promote the progression of atherosclerosis. We hypothesized that PMPs are elevated in Type 2 diabetes and that patients with Type 2 diabetes and clinically apparent atherosclerosis would have the highest levels. Similarly, we hypothesized that soluble plasma P-selectin (sPsel) and CD40L (both molecules which are released by activated platelets), as well as %CD62P (P-selectin) and %CD63 positivity on platelets quantified by flow cytometry, would be highest in patients with Type 2 diabetes and clinically apparent atherosclerotic disease, and might be correlated to PMP levels.

METHODS

Venous blood was obtained from 21 Type 2 diabetic patients without atherosclerotic complications, 18 diabetic patients with clinically apparent atherosclerotic disease and 21 non-diabetic control subjects. PMPs, as well as %CD62P and %CD63 positivity on platelets, were quantified by flow cytometry. sPsel and CD40L were measured using ELISA.

RESULTS

Patients with Type 2 diabetes and clinically apparent atherosclerotic disease had the highest PMP (P=0.045) and sPsel (P=0.046) levels, compared with patients without complications (who had intermediate PMP levels) and control subjects. Control subjects had the lowest CD40L levels (P<0.001) when compared with patients with Type 2 diabetes, with no difference in sCD40L levels between the two diabetic subgroups. %CD62P and %CD63 positivity did not differ between the groups. PMP levels correlated with %CD62P positivity (P=0.026) but not to %CD63 positivity (P=0.089), sCD40L (P=0.407) or sP-sel (P=0.163); sCD40L levels did not correlate with any other marker of platelet activation.

CONCLUSION

PMPs are elevated in Type 2 diabetes. In addition, patients with clinically apparent atherosclerosis had the highest levels of PMPs and sPsel. Thus, PMPs may be a marker of symptomatic atherosclerotic vascular disease in Type 2 diabetes, and may both represent a useful risk stratification tool as well as a novel therapeutic target for anti-thrombotic drugs.

Factors predicting the development of metabolic syndrome and type II diabetes against a background of hypertension

BACKGROUND

The metabolic syndrome (MetS), predicting coronary heart disease (CHD), is a compound of risk factors including diabetes, obesity and hypertension. The relationship between the development of MetS, diabetes and CHD in patients with established hypertension is unclear. We hypothesized that patients with hypertension developing MetS are at increased risk of type II diabetes and CHD compared with patients who do not develop MetS.

MATERIALS AND METHODS

We prospectively studied 284 patients (100 with existing/established MetS) with hypertension but without diabetes and CHD over 4 years. MetS and diabetes were diagnosed by the modified NCEP and ADA criteria, and CHD risk by the Framingham risk equation; all patients had annual fasting blood sampling.

RESULTS

Over 4 years of follow up, 75 of the 184 patients (41%) initially free of MetS at baseline subsequently fulfilled the criteria for MetS. These patients (i.e. 'developing MetS') had higher baseline BMI, triglycerides and lower HDL cholesterol, with a higher calculated CHD risk (all P <or= 0.001) than those who did not develop MetS. The 4-year odds ratios of developing diabetes in the patients with established MetS (23%) and the patients developing MetS (13.3%) vs. the patients not developing MetS (3.7%, P < 0.001) were 7.8 (95% CI: 2.6-23.5) and 4.0 (95% CI: 1.2-13.4), respectively.

CONCLUSIONS

Patients with hypertension developing MetS have an increased CHD risk and risk of developing type II diabetes even before fulfilling the criteria for MetS, and the former is comparable to patients with established MetS. These data suggest a high-risk phase not adequately identified by current diagnostic thresholds for MetS.

Spin waves in nickel nanorings of large aspect ratio

The spin dynamics of high-aspect-ratio nickel nanorings in a longitudinal magnetic field have been investigated by Brillouin spectroscopy and the results are compared with a macroscopic theory and three-dimensional micromagnetic simulations. Good agreement is found between the measured and calculated magnetic field dependence of the spin wave frequency. Simulations show that as the field decreases from saturation, the rings switch from a "bamboo" to a novel "twisted bamboo" state at a certain critical field, and predict a corresponding dip in the dependence of the spin wave frequency on the magnetic field.

The effect of multi-factorial intervention on plasma von Willebrand factor, soluble E-selectin and tissue factor in diabetes mellitus: implications for atherosclerotic vascular disease

BACKGROUND

Endothelial abnormalities and a hypercoagulable state may contribute to increased cardiovascular risk in diabetes mellitus, particularly in patients with overt cardiovascular disease (CVD). We sought to determine the effect of intensified multi-factorial cardiovascular risk intervention on indices of endothelial abnormality and hypercoagulability in diabetes, and if patients with overt CVD would derive similar benefit as those without.

PATIENTS AND METHODS

We measured plasma von Willebrand factor (vWf, an index of endothelial damage/dysfunction), soluble E-selectin (sE-sel, marking endothelial activation) and tissue factor (TF, an initiator of coagulation) by ELISA in 94 patients with diabetes mellitus (38 with CVD and 56 without overt CVD) and 34 comparable controls. Thirty-three patients with CVD and 31 without overt CVD then participated in multi-factorial cardiovascular risk intervention over 1 year.

RESULTS

Plasma levels of vWf (P = 0.009), sE-sel (P < 0.001) and TF (P < 0.001) were significantly higher in diabetic patients compared with controls, with TF highest in patients with overt CVD. Intensive multi-factorial intervention resulted in reductions in glycated haemoglobin (HbA(1c)), total and LDL-cholesterol (all P < 0.05), but no significant weight change. This was associated with reductions in vWf in patients with (by 26%P = 0.003), and without (by 47%, P < 0.001), overt CVD. TF was reduced only in patients without overt CVD (by 45%, P < 0.001). There were no significant changes in sE-sel levels in either group.

CONCLUSION

Endothelial abnormalities in diabetes are only partially influenced by contemporary intensified multi-factorial cardiovascular risk intervention. These data suggest the need for earlier and more aggressive risk factor intervention.

Coercivity of permanent magnetic thin film

The coercivity of magnetic thin film having a two-dimensional easy-axis distribution is investigated within the framework of a simple micromagnetic model. It is found that the coercivity decreases from 0.14H(K) to a minimum of 0.07H(K) as thickness increases, where H(K) is the anisotropy field. It is substantially lower than that given by the Stoner-Wohlfarth model and is consistent with available experimental data. The calculated hysteresis loop and the initial magnetization curve are also in good agreement with experiments.

Tissue inhibitor of metalloproteinse-1 is a marker of diastolic dysfunction using tissue doppler in patients with type 2 diabetes and hypertension

BACKGROUND

Tissue inhibitor of metalloproteinase-1 (TIMP-1) is associated with increased fibrosis of the extracellular matrix (ECM). Myocardial stiffness is a feature of diastolic dysfunction. We assessed circulating TIMP-1 as a marker of diastolic dysfunction in patients with type 2 diabetes mellitus (DM) and hypertension, who were compared with healthy controls.

METHODS

We recruited 54 patients (43 males; mean age 68 +/- 5 years) with treated type 2 DM (i.e. controlled glycaemia, hypertension, hyperlipidaemia), 35 (30 males; 69 +/- 8 years) treated nondiabetic hypertensives, and 31 healthy controls (18 males; 66 +/- 5 years). Circulating TIMP-1 was measured by ELISA. Using transthoracic echocardiography, the early (E) diastolic mitral inflow velocity was measured with pulse wave Doppler, and the early mitral annular velocity (e'), a recognized index of diastolic relaxation, was measured with tissue Doppler. The E/A ratio was also calculated and isovolumic relaxation time measured.

RESULTS

Mean e' levels differed significantly between controls, diabetics and hypertensives (P < 0.0001). Circulating TIMP-1 was significantly different between patients and controls (P = 0.006), but there was no statistically significant difference between the DM and hypertension group. In both groups, only e' was negatively correlated with TIMP-1 levels, with a stronger correlation among the hypertensive patients (Spearman r = -0.544, P = 0.001) when compared with the diabetic group (r = -0.341, P = 0.011).

CONCLUSION

Diastolic relaxation is impaired in diabetes and hypertensive patients. The relationship between TIMP-1 and e' may reflect increased myocardial fibrosis and consequent diastolic dysfunction, which may be more prominent in hypertension.

Brillouin study of the quantization of acoustic modes in nanospheres

The vibrational modes in three-dimensional ordered arrays of unembedded SiO2 nanospheres have been studied by Brillouin light scattering. Multiple distinct Brillouin peaks are observed whose frequencies are found to be inversely proportional to the diameter (approximately 200-340 nm) of the nanospheres, in agreement with Lamb's theory. This is the first Brillouin observation of acoustic mode quantization in a nanoparticle arising from spatial confinement. The distinct spectral peaks measured afford an unambiguous assignment of seven surface and inner acoustic modes. Interestingly, the relative intensities and polarization dependence of the Brillouin spectrum do not agree with the predictions made for Raman scattering.