AU Min Research Articles

Increased exercise-related platelet activation assessed by impedance aggregometry in diabetic patients despite aspirin therapy.

Aspirin is widely used for the prevention of thromboembolic diseases, but inhibition of platelet aggregation (PA) is not uniform. Additionally, aspirin has been shown to be ineffective in blunting PA in response to exercise in patients with coronary artery disease (CAD). Limited data exists about platelet function following acute exercise in diabetics taking aspirin. In our study, we aimed to investigate PA before and after exercise stress test in type-2 diabetic patients taking aspirin. Forty-three patients with type-2 diabetes mellitus (DM) and 36 subjects (age- and sex-matched) as control group were included prospectively. All participants were under aspirin (100mg/day) therapy for at least 1 week. The measures of PA were assessed by impedance aggregometry using arachidonic acid as an agonist(ASPI test). Blood samplings were undertaken before and immediately after treadmill exercise test. At rest, diabetic and control groups had comparable pre-exercise PA (22.97 ± 14.57 versus 22.11 ± 12.71 AUmin, p = NS, respectively). After treadmill exercise, both groups showed significantly higher absolute increase (9.02 ± 13.08 and 3.66 ± 5.87 AUmin, p < 0.01, p < 0.01, respectively) and percent (%) increase (45.67 ± 49.34 and 24.04 ± 46.59 AU min, p < 0.01, p = 0.01, respectively) in PA. Both absolute increase (p < 0.05) and % increase (p < 0.05) in PA were significantly higher in DM group compared to the control group. Multiple regression analysis revealed that high-sensitive C-reactive protein (p = 0.014) was independent predictor of absolute increase PA. Our study showed that aspirin has limited effect in inhibiting exercise-induced PA, even in the absence of documented CAD. The increase in PA following exercise was significantly greater in patients with DM compared with controls.

Platelet aggregation and the risk of stent thrombosis or bleeding in elective percutaneous coronary intervention patients.

: Platelet aggregation monitoring in patients after stent implantation is a promising way of preventing stent thrombosis and bleeding. The aim of the study was to verify whether clopidogrel (ADPtest) and aspirin (ASPItest) response measured by Multiplate (Dynabyte, Munich, Germany) analyzer in elective percutaneous coronary implantation patients predict the risk of stent thrombosis or other ischemic adverse events and bleeding. In this prospective, observational study 697 elective percutaneous coronary implantation patients were analyzed. The median ASPItest was 86 AU min. In 69 patients (9.9%), an ASPI result of more than 203 AU min was observed. The median ADP-dependent platelet aggregation was 212 AU min. In 36 (5.2%) patients, the result was at least 468 AU min. Cox regression analysis showed the prognostic factors of definite or probable stent thrombosis and cardiac death at 1 year were higher ASPItest result [odds ratio (OR) 1.006, 95% confidence interval (CI) 1.004-1.008, P < 0.001], ASPItest more than 203 AU min (OR 7.61, 95% CI 2.83-20.43, P < 0.001), higher ADPtest result (OR 1.005, 95% CI 1.003-1.007, P < 0.001) and ADPtest at least 468 AU min (OR 12.54, 95% CI 4.56-35.53, P < 0.001). In turn, ADPtest 188 AU min or less predicted GUSTO scale major and moderate bleeding (OR 4.15, 95% CI 1.12-15.32, P = 0.033). There was also a strong trend toward higher rate of major and moderate bleeding for the ASPItest less than 35 AU min (lowest quintile) - (OR 3.04, 95% CI 0.96-9.58, P = 0.058). Lower creatinine clearance and lower hemoglobin level were associated with both ischemic and bleeding complications. The results of this study show that impaired platelet response to clopidogrel and aspirin measured by the Multiplate analyzer results in increased risk of stent thrombosis and cardiac death. Furthermore, the study showed that increased response to clopidogrel is related to major and moderate bleeding events.

Molecular Identification of Alleles on Lpx-B1 Locus and Lipoxygenase Activity in Durum Wheat ( Triticum turgidum L.)

Lipoxygenase(LOX) has a close relationship to the processing quality of flour products in durum wheat(Triticum turgidum L.). Activity of LOX is greatly influenced by the locus of Lpx-B1. The Lpx-B1 alleles in 167 durum wheat varieties from different countries or regions were identified using gene-specific primers, and the Lpx-B1 genotypes were analyzed based on LOX activity data. The LOX activity varied greatly in the 167 varieties, ranging from 0.20 to 7.98 AU min–1 g–1. On Lpx-B1.1 locus, three alleles(Lpx-B1.1a, Lpx-B1.1b, and Lpx-B1.1c) were identified with frequencies of 55.1%, 7.8%, and 37.1%, respectively. Loci Lpx-B1.2 and Lpx-B1.3 were always reciprocally present in varieties, in which Lpx-B1.2 was presented in 146 varieties and Lpx-B1.3 in the remaining 21 varieties. This result indicates the allelic possibility of Lpx-B1.2 and Lpx-B1.3. In the three Lpx-B1.1 genotypes, the Lpx-B1.1b varieties had significantly higher LOX activity than the Lpx-B1.1a and Lpx-B1.1c varieties, and varieties carrying Lpx-B1.1c allele possessed the lowest LOX activity. The LOX activity in Lpx-B1.3 genotypes was significantly higher than that in Lpx-B1.2 genotypes. A total of six genotypic combinations were found on the three Lpx-B1 loci in 167 varieties. Among them, Lpx-B1.1b/Lpx-B1.3 combination had the highest LOX activity and combinations of Lpx-B1.1c/Lpx-B1.2 and Lpx-B1.1c/Lpx-B1.3 had the lowest LOX activity. These results are informative to quality breeding of durum wheat.

Impact of CYP2C19 polymorphism on residual platelet reactivity in patients with coronary heart disease during antiplatelet therapy

CYP2C19*2 loss-of-function allele in Caucasians may be associated with wide interindividual variability in platelet response to clopidogrel, and the incidence of gene mutation varies with racial differences, especially between Asians and Caucasians. The aim was to examine the impact of CYP2C19 genotype on the residual platelet reactivity in Japanese patients with coronary heart disease (CHD) during antiplatelet therapy. We measured the CYP2C19 genotype and platelet aggregation in 201 patients with stable CHD. Moreover, we examined the relation of CYP2C19 polymorphism to cardiovascular events in 98 patients treated with stent implantation. The distribution of CYP2C19 genotype was 37%, 33%, 11%, 11%, 7%, and 1% in CYP2C19*1/*1, *1/*2, *1/*3, *2/*2, *2/*3, and *3/*3, respectively. Residual platelet reactivity was lower in patients during dual antiplatelet therapy (DAT) than in those with aspirin (3975 ± 1569 aggregation units minute (AU min) vs 5850 ± 938 AU min, p<0.05). In the DAT group, the platelet reactivity decreased significantly in the wild-type homozygotes (CYP2C19*1/*1), subsequently in the *2, or *3 heterozygotes (*1/*2, *1/*3), and was not well inhibited in the *2, and/or *3 homozygotes (*2/*2, *2/*3, *3/*3; 3194 ± 1570 AU min, 4148 ± 1400 AU min, and 5088 ± 1080 AU min, respectively). However, when the duration of DAT was used to divide subjects into 2 groups, <7 days, and >7 days, patients carrying the variant allele showed significantly decreased platelet reactivities at >7 days compared with those at <7 days. Moreover, the incidence of cardiovascular events was higher in patients carrying at least one variant allele than in wild-type homozygotes. CYP2C19 polymorphism may be associated with high residual platelet reactivity and the occurrence of cardiovascular events.

Determination of inorganic oxyhalide disinfection by-products in bottled water by EPA Method 326.0 for trace bromate analysis

An ion chromatography method with post-column reaction and optical detection, according to EPA Method 326.0, for the determination of bromate has been developed and validated in water samples. Optimization of reaction and operating conditions (post-column reagent and sulphuric acid regenerant flow rate) made possible to minimize the background noise and attain low detection limit. Employing a carbonate elluent (9.0 mM Na 2CO 3) at a flow rate of 1.1 ml/min and a sample loop of 250 μl, a detection limit for bromate of 0.33 μg/l and a quantification limit (LOQ) of 0.99 μg/l were generated. Under these conditions bromate and chlorite were separated (resolution factor >2.5) in an analysis time of less than 6.5 min and the important validation parameters were evaluated. Calibration curve in laboratory-grade water produced excellent regression in the range from LOQ up to 20μg/l in the order of r 2=0.99, whereas a range of applicability of 0.99 μg/l to 100 μg/l was confirmed. UV detector response (AU ⁎min/(μg/l)) was almost constant (± 2%) at various concentration levels. The recoveries obtained in the accuracy test for all aqueous matrices studied were in the 93.1–106% range and the intraday and interday precisions (expressed as coefficient of variation, CV) were smaller than 13.5%. Expanded uncertainty (95%) was calculated at various concentration levels according to propagation error theory (1±0.28 μg/l, 5±0.44 μg/l, 10±0.60 μg/l).

In Situ Transient FTIR and XANES Studies of the Evolution of Surface Species in CO Oxidation on Au/TiO2

The adsorption of CO and its reaction with oxygen were investigated using a combination of in situ Fourier transform infrared spectroscopy, step response measurements in a microreactor, (18)O isotopic labeling, and X-ray absorption near edge structure spectroscopy. An as-prepared sample in which Au is present as a surface oxyhydroxy complex does not adsorb CO. On an activated sample in which only metallic Au is detected, 0.18 +/- 0.03 mol CO/(mol Au) are adsorbed on Au at -60 degrees C, which shows an IR band at 2090 cm(-1). When oxygen is present in the gas phase, this species reacts with a turnover rate of 1.4 +/- 0.2 mol CO(mol Au min)(-1), which is close to the steady-state turnover rate. In contrast, there is a very small quantity of adsorbed oxygen on Au. A small IR peak at 1242 cm(-1) appears when an activated sample is exposed to CO. It reacts rapidly with oxygen and is shifted to 1236 cm(-1) if (18)O is used. It is assigned to the possible intermediate hydroxycarbonyl.

Rate of browning reaction during preparation of coconut and palm sugar

The objective of this research was to analyse the rate of browning reaction during preparation of palm and coconut sugar. Brown colour formation during preparation of coconut sugar at a laboratory scale followed a zero order reaction with a constant of formation (k) equal to 5.15×10−3 AU min−1 (AU=Absorbance Unit). The amount of glucose, fructose and sucrose decreased during this preparation and the decrease followed a zero order reaction for glucose, first order for fructose, whereas that for sucrose followed neither zero nor first order reaction. After 90 min boiling (when the coconut sugar was formed), the amounts of glucose, fructose and sucrose left were 27.7%, 35.7% and 83.7% of the initial amount, respectively. The relative percentage area of furans and pyrazines increased during the preparation of coconut sugar and this increase followed a first order reaction for both.The palm sap with initial pH adjusted to 8.0 was heated in a closed system at temperatures of 105, 115 and 121 °C for up to 300 min and every 30 min, the brown colour of the sap was measured at 420 nm. The brown colour formation followed a zero order reaction with k equal to 0.87×10−3, 4.46×10−3, 6.58×10−3 AU min−1 for reaction temperatures of 105, 115 and 121 °C, respectively. The activation energy of the brown colour formation was 160.77 J mol−1. In a separate experiment, an aqueous solution containing glucose, fructose and sucrose at a concentration of 3.42%, 1.56% and 7.22%, respectively, with and without addition of 0.01% l-lysine, each was adjusted to pH 8.0 and heated at 121 °C and analysed as above. The rate of brown colour formation that resulted from heating model aqueous solution containing sugars and l-lysine resembled that resulting from heating palm sap. Therefore, the Maillard reaction plays an important role in the formation of brown colour during preparation of palm sugar.