Risk of adverse outcomes in Taiwan associated with concomitant use of clopidogrel and proton pump inhibitors in patients who received percutaneous coronary intervention

Recent studies have suggested that proton pump inhibitors (PPIs) might reduce the inhibitory effect of clopidogrel on platelet aggregation, possibly through inhibition of the hepatic cytochrome P450 2C19 (CYP2C19) isoenzyme. The prevalence of CYP2C19 loss-of-function alleles is much greater among East Asians than among other populations. Thus, potential drug interactions might be more apparent. Therefore, we conducted a nationwide, population-based study using the Taiwan National Health Insurance database. We identified 3,278 patients (mean age 65.9 +/- 11.9 years, 71.9% men) with coronary artery disease who had taken clopidogrel after percutaneous coronary intervention from the 1 million sampling cohort data set since January 1, 2002. Of the 3,278 patients, 572 had received concomitant PPIs for underlying gastrointestinal disease and 2,706 had not used PPIs. To the end of 2007, 1,410 patients had been rehospitalized, 970 patients had undergone revascularization, and 499 patients had died. According to the Kaplan-Meier analysis, the incidence of rehospitalization (p = 0.001) and mortality (p <0.001) was significantly greater for the patients with concomitant PPI use than for those without concomitant PPI use. However, the incidence of revascularization was similar in the 2 groups. Multivariate analyses showed that concomitant PPI use was associated with an increased risk of rehospitalization (hazard ratio 1.23, 95% confidence interval 1.07 to 1.41, p = 0.003) and mortality (hazard ratio 1.65, 95% confidence interval 1.35 to 2.01, p <0.001). In conclusion, the concomitant use of clopidogrel and PPIs should be done with care to avoid adverse outcome in East Asians patients who have undergone percutaneous coronary intervention.

Vibrational resonance in neuron populations

In this paper different topologies of populations of FitzHugh-Nagumo neurons have been introduce to investigate the effect of high-frequency driving on the response of neuron populations to a subthreshold low-frequency signal. We show that optimal amplitude of high-frequency driving enhances the response of neuron populations to a subthreshold low-frequency input and the optimal amplitude dependences on the connection among the neurons. By analyzing several kinds of topology (i.e., random and small world) different behaviors have been observed. Several topologies behave in an optimal way with respect to the range of low-frequency amplitude leading to an improvement in the stimulus response coherence, while others with respect to the maximum values of the performance index. However, the best results in terms of both the suitable amplitude of high-frequency driving and high stimulus response coherence have been obtained when the neurons have been connected in a small-world topology.

Harmonics and intermodulation in subthreshold FitzHugh-Nagumo neuron

Intermodulation and harmonics are important in frequency analysis of nonlinear systems. In neuron research, most investigations are taken in studying synchronization between the external stimuli and the output of neuron, but harmonics and intermodulation are often ignored. In this paper, harmonics and intermodulation of the subthreshold FitzHugh-Nagumo neuron are investigated and their magnitudes are used to predict frequency response of the neuron. Furthermore, through analyzing the magnitudes of harmonics, the intrinsic frequencies of the neuron could be identified.

Comparison of total knee arthroplasty using computer-assisted navigation versus conventional guiding systems: a prospective study

PURPOSE

To compare knee alignments in total knee arthroplasty (TKA) using computer-assisted navigation versus conventional guiding systems.

METHODS

Five men and 49 women aged 49 to 79 years underwent TKA for primary osteoarthritis of the knee with varus deformity. All valgus knees were associated with inflammatory arthritis and thus excluded. Computer-assisted navigation was used for the first 35 TKAs, whereas conventional extramedullary tibial and intramedullary femoral guiding systems were used for the next 35 TKAs. The mechanical axis, coronal tibial and femoral angles, sagittal tibial and femoral angles in the 2 groups were compared.

RESULTS

Sagittal tibial and femoral angles aligned more optimally in TKAs using computer-assisted navigation. In the respective computer-assisted navigation and conventional guiding systems, 33 (94%) and 26 (74%) of the TKAs attained a postoperative mechanical axis of <3 degrees varus/valgus.

CONCLUSION

Computer-assisted navigation gives a more consistent alignment correction and reduces outliers during implant positioning.

Kinetic Monte Carlo simulations compared with continuum models and experimental properties of pattern formation during ion beam sputtering

Kinetic Monte Carlo simulations model the evolution of surfaces during low energy ion bombardment using atomic level mechanisms of defect formation, recombination and surface diffusion. Because the individual kinetic processes are completely determined, the resulting morphological evolution can be directly compared with continuum models based on the same mechanisms. We present results of simulations based on a curvature-dependent sputtering mechanism and diffusion of mobile surface defects. The results are compared with a continuum linear instability model based on the same physical processes. The model predictions are found to be in good agreement with the simulations for predicting the early-stage morphological evolution and the dependence on processing parameters such as the flux and temperature. This confirms that the continuum model provides a reasonable approximation of the surface evolution from multiple interacting surface defects using this model of sputtering. However, comparison with experiments indicates that there are many features of the surface evolution that do not agree with the continuum model or simulations, suggesting that additional mechanisms are required to explain the observed behavior.

Stress-enhanced pattern formation on surfaces during low energy ion bombardment

Ion-induced surface patterns (sputter ripples) are observed to grow more rapidly than predicted by current models, suggesting that additional sources of roughening may be involved. Using a linear stability analysis, we consider the contribution of ion-induced stress in the near surface region to the formation rate of ripples. This leads to a simple model that combines the effects of stress-induced roughening with the curvature-dependent erosion model of Bradley and Harper. The enhanced growth rate observed on Cu surfaces appears to be consistent with the magnitude of stress measured from wafer curvature measurements.

Prevalence and clinical characteristics of simple renal cyst

BACKGROUND

We investigated simple renal cysts to understand the prevalence in healthy individuals and evaluate their clinical characteristics to determine whether or not there are any risk factors associated with simple renal cysts.

METHODS

Abdominal sonography was performed in 577 individuals (317 men, 260 women; mean age, 48.84 years; age range, 20-94 years) who received health check-up in January to February 2005. Data including age, sex, renal sonographic findings (cyst number, site, diameter, renal stones), values of serum cholesterol, glucose and creatinine, urine analysis (proteinuria, hematuria, pyuria), and smoking habit were analyzed.

RESULTS

The overall prevalence of simple renal cysts was 10.7%, ranging from 2.38% in the 2nd to 35.29% in the 7th or later decade of life. The prevalence increased with age (p<0.001). The mean age of individuals with cysts was significantly older than those without cysts (57.65+/-13.35 vs. 47.78+/-12.40 years; p<0.001). Male-to-female ratio was 2.81 (15.14% vs. 5.38%; p<0.001). The majority of cysts were solitary (82.3%). Mean largest diameter of cysts was 20.89+/-12.62 mm. The mean size of cysts in every age group was not statistically different. Factors significantly associated with simple renal cysts were age (odds ratio [OR], 4.37; p<0.001), sex (OR, 0.32; p<0.001), serum creatinine (OR, 11.77; p=0.001), proteinuria (OR, 3.11; p=0.004), renal stone (OR, 2.47; p=0.006), and smoking (OR, 2.80; p<0.001). However, in multivariate analysis, except proteinuria, all of the above factors were significantly related to the occurrence of simple renal cysts.

CONCLUSION

The overall prevalence of simple renal cysts in healthy individuals was 10.7%. Age, sex, renal stone, serum creatinine, and smoking were found to be risk factors for the presence of simple renal cysts.

Compositionally modulated ripples induced by sputtering of alloy surfaces

Sputtering of an amorphous or crystalline material by an ion beam often results in the formation of periodic nanoscale ripple patterns on the surface. In this Letter, we show that, in the case of alloy surfaces, the differences in the sputter yields and surface diffusivities of the alloy components will also lead to spontaneous modulations in composition that can be in or out of phase with the ripple topography. The degree of this kinetic alloy decomposition can be altered by varying the flux of the ion beam. In the high-temperature and low-flux regime, the degree of decomposition scales linearly with the ion flux, but it scales inversely with the ion flux in the low-temperature, high-flux regime.

Thumb polydactyly: clinical outcome after reconstruction

PURPOSE

To evaluate clinical and cosmetic outcomes of reconstruction in thumb polydactyly and prognostic value of the Wassel classification.

METHODS

Between 1993 and 2000 inclusive, out of the patients with thumb polydactyly (involving 80 thumbs) operated on, 34 patients (36 thumbs) were available for review and underwent clinical and radiological assessment. Outcomes in terms of the Tada score and complications were recorded.

RESULTS

The mean age of patients at the time of operation was 2.8 (range, 0.6-47) years. The mean follow-up period was 5 (range, 2.4-10) years. According to the Wassel classification, 12 were type-II thumb polydactyly, 3 type-III, 11 type-IV, 6 type-V, one type-VI, and 3 type-VII. There was no perioperative mortality or wound infection. More than 88% of the patients were satisfied or very satisfied with functional and cosmetic outcomes. Postoperative complications such as scar hypertrophy, pulp atrophy, joint deformity, and instability were common but minor. Ridge nail deformity after the Bilhaut Cloquet procedure was amenable to secondary corrective procedures. All types of operated thumb polydactyly achieved similar mean Tada scores (14.7- 16.6 out of 20). The Wassel classification category, age, and surgical procedures were found to have no prognostic value with regard to the Tada score and presence of complications.

CONCLUSION

Surgery on thumb polydactyly is rewarding. The Wassel classification category can be used as a guide for treatment, although it fails to predict the occurrence of postoperative complications or Tada scores. Our patients' results can serve as guidelines of expected outcomes after reconstructive procedures in different sub-types of thumb polydactyly.

Breakage of intramedullary femoral guide rod during total knee arthroplasty: a case report

We report a rare complication during primary total knee arthroplasty. An intramedullary femoral guide rod was broken during insertion. The broken part jammed into the isthmus of the femur. An initial attempt to push the broken rod via the proximal femur by a guide wire to the distal femur was unsuccessful because the broken rod was lodged in the isthmus. Ultimately, the isthmus was opened using a flexible 9-mm end-cutting reamer, and the broken rod was pushed down to the distal femoral entry site in an antegrade fashion under image intensification. Selecting a more medial entry site on the intercondylar notch with a smaller valgus cutting angle and using a shorter guide rod can avoid such a breakage.

Is hyperuricemia another facet of the metabolic syndrome?

BACKGROUND

Hyperuricemia is commonly associated with obesity, glucose intolerance, hypertension, dyslipidemia, and atherosclerotic cardiovascular disease. The resemblance of the metabolic syndrome and hyperuricemia has led to the suggestion that hyperuricemia is a part of the metabolic syndrome. The purpose of this study is to examine the contribution of uric acid (UA) as an additional component of the metabolic syndrome in middle-aged men.

METHODS

In total, 393 male participants, aged 45-60 years, were recruited from a professional health evaluation program. Anthropometric measurements and blood pressure (BP) were taken after an overnight fast. Fasting blood samples were collected for the measurements of glucose, UA, and lipid profile. Logistic regression models were fitted to examine the relationship between UA and the diagnosis of metabolic syndrome. Factor analysis was performed to explore the relationship between UA and the components of the metabolic syndrome.

RESULTS

The diagnosis of the metabolic syndrome was significantly associated with waist circumference (WC), glucose, triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), systolic BP, and liver enzyme levels, but not associated with UA levels. The sensitivity of hyperuricemia (serum UA > or = 7.0 mg/dL) for the diagnosis of the metabolic syndrome was 58.0% and the specificity was 55.3%. In factor analysis, UA aggregated with body mass index, WC, glucose, log TG, and HDL-C as a metabolic factor. Systolic and diastolic BP were loaded on a second factor separately. The model loaded with UA explained a similar proportion of the total variance (56.9%), as did the model loaded without UA (62.5%).

CONCLUSION

Our results suggest that the contribution of UA as an additional component of the syndrome seems to be insignificant. We propose that hyperuricemia might not be an important facet for the understanding of the underlying structure of the metabolic syndrome.

Feasibility and accuracy of 64-row MDCT coronary imaging from a centre with early experience: a review and comparison with established centres

The accuracy of multi-detector computed tomographic (MDCI) coronary angiography (CTA) is dependant on image quality as well as the experience of the operator. Established centers have reported negative predictive values of over 95%. The aim of our study was to investigate the accuracy and feasibility of CTA for the assessment of haemodynamically significant coronary stenosis in a center with very early experience (<6 months) utilizing the improved spatial and temporal resolutions of the latest generation 64-row MDCI scanner. One hundred and twenty eight patients (93 male, 35 female; mean age 56.2 +/- 9.5 years) with suspected or known coronary artery disease underwent both CIA and conventional coronary angiographv (CCA). The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values for stenoses > or =50% by CIA compared to CCA were 70%, 97%, 70% and 97% respectively. Evaluation of main and proximal segments in patients with good quality images (78% of patients) produced values of 94%, 95%, 74% and 99% respectively. The improved spatial and temporal resolutions of 64-row MJ) CT provided a high negative predictive value in assessing significant coronary artery stenosis even in a centre with very early experience. However, new centers embarking on CTA might not be able to reproduce the results reported by more experienced centers.

Double-barrel coronary artery dissection

Coronary artery dissection is a common occurrence after percutaneous transluminal coronary angioplasty (PTCA). However, we report herein a rare case of double-barrel coronary artery dissection occurring 1 year after PTCA for stenosis in the left circumflex coronary artery. The case history and angiographic findings are reported, and relevant literature is reviewed.

Congenital absence of the left circumflex coronary artery

We report a rare case of congenital coronary artery anomaly with recurrent chest pain. A 44-year-old Taiwanese female patient presented with exertional chest pain that had lasted for 2 years. An electrocardiogram showed right axis deviation and an rS pattern in leads I and aVL, and an exercise stress test was inconclusive. A thallium-201 myocardial perfusion study revealed perfusion defects in the septal and inferior walls which normalized in the delayed imaging. Coronary angiography revealed the absence of a left circumflex coronary artery and a superdominant right coronary artery with terminal branches supplying the left ventricular inferior and posterolateral walls. An aortogram revealed no evidence of the existence of a left circumflex coronary artery. Administration of nitrates and calcium antagonists could not ameliorate her symptoms, but she remained stable during ordinary activity. In young premenopausal female patients who present with symptoms suggestive of angina pectoris and a positive stress test, congenital anomaly of the coronary artery should be considered and an angiographic study should be performed.

Clinical characteristics and endoscopic findings associated with Blastocystis hominis in healthy adults

Ninety-nine individuals with stools positive for Blastocystis hominis but negative for other parasites were identified from medical records of healthy adults who had received a physical examination at Taipei Veterans General Hospital from November 2000 to October 2002. The medical records of these 99 positive cases and 193 randomly selected controls, matched for age, sex, and date of examination, were retrospectively reviewed. The pathogenicity of B. hominis could not be demonstrated due to a lack of association with the development of gastrointestinal symptoms or pathologic findings on endoscopic examination. Multivariate analyses revealed that chronic hepatitis B infection was a predisposing condition to the acquisition of B. hominis (odd ratio = 2.848, 95% confidence interval = 1.299-6.242, P = 0.009), and concentration of urate was significantly lower in B. hominis-positive individuals (mean +/- SD = 361.64 +/- 87.44 versus 392.57 +/- 93.38 micromol/L; P = 0.009). Among the 64 individuals who underwent gastric biopsy, Helicobacter pylori was found more frequently in the individuals harboring B. hominis (19 of 26 versus 15 of 38; P = 0.017).

Impairment of coronary microvascular function in patients with neurally mediated syncope

Recent evidence suggests that myocardial ischemia may occur in patients with neurally mediated syncope and normal coronary angiograms. This study was conducted to evaluate if coronary microvascular function is impaired in such patients. Coronary hemodynamic studies and head-up tilt table tests (HUTs) were performed on 30 consecutive patients with normal coronary angiograms and recurrent syncope. Another ten subjects with atypical chest pain and no evidence of myocardial ischemia or syncope served as a control. Great cardiac vein flow (GCVF) and coronary sinus flow (CSF) were measured by the thermodilution method at baseline and after dipyridamole infusion (0.56 mg/kg i.v. for 4 minutes). Coronary flow reserve (CFR), derived from CSF and GCVF, was significantly lower in the 15 patients with positive HUT than in the other 15 patients with negative HUT (1.75 +/- 0.48 vs 2.64 +/- 0.8, P < 0.01 and 2.29 +/- 0.45 vs 3.07 +/- 0.63, P < 0.01, respectively). Ischemic-like ECG was noted during treadmill exercise test in 40% of the former and in 7% of the latter group (P = 0.01). There was no significant difference in CFR between patients with negative HUT and control subjects. Coronary microvascular function was impaired in syncopal patients with positive HUT and relatively preserved in those with negative HUT, suggesting the possible linkage between coronary microvascular dysfunction and the development of neurally mediated syncope.

Clinical and angiographic determinants of adverse cardiac events in patients with stent restenosis

Patients with angiographically proven stent restenoses do not necessarily develop adverse cardiac events. Which clinical, procedural, or angiographic parameters relate to the development of adverse cardiac events among these patients has not been determined. This study included 155 patients (167 stented lesions) with angiographically proven restenosis (> or = 50% diameter stenosis) within the stent or at its margins in routine follow-up angiograms that was obtained at 6.5 +/- 3.6 months after successful stenting. Thirty-six patients (22%) had adverse cardiac events (including unstable angina necessitating target lesion revascularization, acute myocardial infarction, or cardiac death) during follow-up and 119 patients (78%) were event-free. These two groups of patients were compared to determine the parameters related to adverse cardiac events. Univariate determinants of adverse events included hypertension (P = 0.023), unstable angina at initial presentation (P = 0.002), target lesion in proximal left anterior descending artery (P = 0.041), TIMI grade 0-2 flow in follow-up angiograms (p < 0.001), impaired left ventricular function at follow-up (P = 0.002), follow-up minimal lumen diameter < or = 0.6 mm (P = 0.003), follow-up diameter stenosis > 75% (P = 0.005), late loss > 2 mm (P = 0.01), and loss index > 1.127 (P < 0.001). Multivariate analysis demonstrated hypertension (odds ratio, OR, = 3.6; P = 0.019), unstable angina at initial presentation (OR = 2.6; P = 0.007), TIMI grade 0-2 flow at follow-up (OR = 2.8; P = 0.05), impaired LV function at follow-up (OR = 4.2; P = 0.004), and loss index > 1.127 (OR = 3.6; P = 0.017) as independent risk factors for adverse cardiac events. Classification and regression tree analysis identified loss index > 1.127 and impaired LV function as the two strongest determinant of adverse cardiac event. Therefore, hypertensive patients whose initial clinical presentation were unstable angina should be managed carefully to optimize the angiographic results and, most importantly, followed up more closely for development of impaired LV function after coronary stenting in order to prevent the occurrence of adverse cardiac event at follow-up.

Autotuning positive feedback time delay controller for dead time processes

Biased relay feedback tests are applied to dead time processes to obtain their ultimate gains and ultimate frequencies. First-order process with dead time models are then fitted to the estimated gains and frequencies. A time delay controller that incorporates a simple compensator with a delay element in positive feedback can be derived from the fitted model. The time delay controller gives better performance comparing with classical Ziegler and Nichols tuned PID controller. Experimental study is included to demonstrate the effectiveness of the proposed tuning scheme and the time delay control algorithm.

Leukocyte mitochondria depolarization and apoptosis in advanced heart failure: clinical correlations and effect of therapy

OBJECTIVES

The purpose of this study was to examine the changes in leukocyte mitochondrial transmembrane potential (MTP) and its association with apoptosis in congestive heart failure (CHF).

BACKGROUND

Congestive heart failure is a heterogeneous syndrome with multiple hemodynamic, neuroendocrine and immune abnormalities. Although edematous CHF may be associated with endotoxemia and increased cytokine production, peripheral blood leukocyte functions in advanced CHF remain unclear.

METHODS

Thirty patients with acute decompensated CHF (mean age [+/- SEM] 74.9 +/- 3.1 years) and 20 healthy controls underwent determination of MTP, intracellular oxidants and apoptosis in three subsets of peripheral blood leukocytes. The measurements were repeated after the time of recompensation.

RESULTS

Patients with acute CHF showed marked MTP reduction and increased intracellular oxidant formation in three subsets of leukocytes upon entry into the study. These changes were more prominent in patients with peripheral edema. The decline in MTP was correlated with the severity of the peripheral edema and plasma concentration of cortisol, nitrogen metabolites and tumor necrosis factor-alpha (p < 0.01). After clinical stabilization, MTP gradually recovered. Leukocytes underwent increased propensity of apoptosis one week after the time of recompensation.

CONCLUSIONS

The mitochondrial depolarization and apoptosis of leukocytes in decompensated heart failure suggest that CHF is associated with severity-dependent impairments in leukocyte function. Accentuated hormonal and cytokine abnormalities and increased circulating oxidants may contribute to these changes. Early and aggressive management of advanced heart failure is helpful in the recovery of these immune abnormalities.

Coincidence detection FDG PET in the management of oncological patients: attenuation correction versus non-attenuation correction

The aim of this study was to determine if attenuation correction (AC) in a dual-head, coincidence, positron emission tomography imaging system (Co-PET) improved image quality, lesion detection, patient staging and management of various malignant neoplasms, compared to non-attenuation corrected (NAC) images. Thirty patients with known or suspected malignant neoplasms underwent fluorodeoxyglucose (FDG) Co-PET, which was correlated with histopathology, computed tomography (CT) and other conventional imaging modalities and clinical follow-up. The number and location of FDG avid lesions detected on the AC images and NAC Co-PET images were blindly assessed by two independent observers. Semi-quantitative grading of image clarity and lesion-to-background quality was performed. This revealed markedly improved image clarity and lesion-to-background quality in the AC versus NAC Co-PET images. AC Co-PET was statistically superior to NAC Co-PET in relation to lesion detection (P<0.01) and tumour staging (P<0.01). NAC Co-PET demonstrated 51 of the 65 lesions (78%) detected by AC Co-PET. AC Co-PET altered tumour staging in five additional patients (16%) compared to NAC Co-PET. Management was altered in two of these five patients.

Regulation of ST2L expression on T helper (Th) type 2 cells

T1/ST2L, an IL-1 receptor homologue, is selectively expressed on murine Th2 cells and specific anti-ST2L antibodies can profoundly modulate the Th1/Th2 balance in vivo. Naive CD4+ T cells do not express ST2L but do so on activation with specific antigen in the presence of IL-4 or when stimulated with low doses of antigen in the absence of exogenously added IL-4. Similarly enhanced ST2L expression occurred after stimulation of Th2 cells with antigen or the mitogen ConA in the presence of APC. Restimulation of Th2 cells in the presence of IFN-gamma led to a decreased expression of ST2L to below basal levels. Conversely, Th2 cells cultured with IL-4 led to increased ST2L expression. The reduced expression of ST2L in response to high doses of antigen is also reversed by the neutralization of IFN-gamma. Using an ST2L promoter/luciferase reporter gene construct, we show that the distal but not proximal ST2L promoter is responsible for specific gene expression in Th2 cells. IL-4 enhances, whereas IFN-gamma suppresses ST2L expression via direct modulation of the distal promoter of the ST2L gene. These data provide a mechanistic explanation for the selective expression of ST2L on Th2 cells.

Human IL-18 receptor and ST2L are stable and selective markers for the respective type 1 and type 2 circulating lymphocytes

CD4(+) (Th) and CD8(+) (Tc) T and NK lymphocytes can be divided into type 1 and 2 subsets according to their cytokine secretion profile. Studies on the role of lymphocyte subsets in human diseases have been hampered by the lack of stable surface markers to define them. Recently, we reported that ST2L and IL-18R are stably expressed on murine Th2 and Th1 cells, respectively. In this study, we generated Abs to human homologues of ST2L and IL-18R and tested them against Th1/Th2, Tc1/Tc2, and NK1/NK2 lines and PBMCs from healthy individuals. We show for the first time that ST2L and IL-18R are stable selective cell surface markers for human Th2/Tc2/NK2 and Th1/Tc1/NK1 lymphocytes, respectively. We then investigated PBMCs from HIV-infected patients and HIV-negative individuals, to test whether Abs to these two surface markers could be used directly to monitor lymphocyte subset distribution in human diseases. We found a clear Th1 to Th2 shift in the HIV-infected individuals, thus settling a long-standing controversy and include, for the first time, Tc and NK cells as well. Therefore, these cell surface molecules could serve as important determinants of the immune status of human diseases in general, and thereby could be useful for therapeutic monitoring and intervention.