Chia-Lun Chao

Effects of Methionine-Induced Hyperhomocysteinemia on Endothelium-Dependent Vasodilation and Oxidative Status in Healthy Adults

BACKGROUND Homocysteine-mediated endothelial dysfunction has been proposed to occur via oxidative stress mechanisms in humans. However, there is controversy regarding the effects of homocysteine on endothelial function and oxidative status, which may in part result from age discrepancy across the studies. The present study was designed to investigate the aging effect on the relationship between endothelium-dependent vasodilation and oxidative status in methionine-induced hyperhomocysteinemia. METHODS AND RESULTS Plasma homocysteine, phosphatidylcholine hydroperoxide (PCOOH), P-selectin levels, and brachial artery flow-mediated vasodilation were measured at baseline and 4 hours after an oral methionine load (0.1 g/kg) in 15 younger (21 to 40 years) and 15 older (55 to 70 years) healthy adults. Homocysteine increased from 7.3+/-1.3 micromol/L at baseline to 22.7+/-5.2 micromol/L at 4 hours in younger (P<0.001) and from 7. 4+/-1.4 to 24.3+/-4.5 micromol/L in older adults (P<0.001). PCOOH levels were not significantly different between baseline and 4 hours in both groups (P=0.10 in young; P=0.14 in old). P-selectin, which is expected to increase during oxidative stress, was not changed in older (P=0.08) but decreased in younger adults (P=0.037) at 4 hours. Flow-mediated vasodilation was preserved from 13.1+/-2.1% at baseline to 13.5+/-2.8% at 4 hours in younger (P=0.49) and decreased from 12.8+/-2.4% to 8.5+/-2.8% in older adults (P<0.001). CONCLUSIONS The present study demonstrates that endothelial dysfunction caused by methionine-induced hyperhomocysteinemia is age-related and is mediated through impaired nitric oxide activity without change of oxidative status. Our data do not support previous hypotheses that endothelial damage by homocysteine is via oxidative stress mechanism in humans.

The relationship between serum galectin-3 and serum markers of cardiac extracellular matrix turnover in heart failure patients

BACKGROUND A growing body of evidence links macrophage activation and fibrosis to the pathogenesis of heart failure (HF). Galectin-3 is one of the most likely mediators between macrophage activation and myocardial fibrosis. However, the exact relationship is unknown in humans. We assessed the impact of galectin-3 on serum markers of cardiac extracellular matrix (ECM) turnover in HF patients. METHODS Patients with HF manifestations and a left ventricular ejection fraction (LVEF) <or=50% were enrolled in this study. Gender, age, medications, serum biochemical data, and outcomes of heart failure were recorded. Serum galectin-3, extracellular matrix including type I and III aminoterminal propeptide of procollagen (PINP and PIIINP), matrix metalloproteinase-2 (MMP-2), and tissue inhibitor of metalloproteinase-1 (TIMP-1) were analyzed. RESULTS A total of 106 (83 males and 23 females) patients were enrolled. The age was 61+/-16 y and LVEF was 35+/-9%. Their mean NYHA functional class was 2.2. Log galectin-3 was significantly correlated with log PIIINP (p=0.006), log TIMP-1 (p=0.025), log MMP-2 (p=0.016), and NYHA functional class (p=0.034); but not age, sex or LVEF. After adjusting for age, sex, smoking status and LVEF, the relationship between galectin-3 and ECM turnover biomarkers (including PIIINP, TIMP, and MMP-2) remained significant. After adjusting for age, sex, smoking status and NYHA functional class, the relationship between galectin-3 and PIIINP or MMP-2 remained significant. CONCLUSIONS Galectin-3 is significantly correlated with serum markers of cardiac ECM turnover in HF patients. This implies a relationship between macrophage activation and ECM turnover in patients with HF.

The graded effect of hyperhomocysteinemia on the severity and extent of coronary atherosclerosis

It is not clear to what extent methylenetetrahydrofolate reductase (MTHFR) gene and hyperhomocysteinemia effect the severity and extent of coronary atherosclerosis in Asian populations. We examined the MTHFR genotypes and plasma homocysteine (HCY) concentrations in 192 Taiwanese and investigated their relationship with coronary artery disease (CAD), and the severity and extent of coronary atherosclerosis. The distribution of MTHFR genotypes was similar in 116 CAD patients and 76 non-CAD subjects. Homozygosity was noted in 8% of CAD patients and 13% of non-CAD subjects (P=0.33; 95% CI, 0. 2-1.6). The geometric mean of HCY values was higher in CAD patients (11.10+/-1.51 micromol/l) than in non-CAD subjects (9.21+/-1.55 micromol/l) (P=0.003). HCY levels were higher in patients with multi-vessel disease (P<0.05) or in patients with > or = 90% stenotic lesions (P=0.005), compared with non-CAD subjects. The CAD risks in the top two HCY quartiles (> or = 14.0 and 10.1-13.9 micromol/l) were 4.0 (95% CI, 1.7-9.2) and 3.2 (95% CI, 1.4-7.4) times higher than in the lowest quartile (< or = 7.9 micromol/l) (P=0.001 and 0.007, respectively). Linear regression analysis showed significant correlations between HCY concentrations and the severity and extent of atherosclerosis (P=0.0001 for both). In conclusion, hyperhomocysteinemia appears to have a graded effect on the risk of CAD as well as the severity and extent of coronary atherosclerosis. Our findings do not support the homozygous genotype of MTHFR as a genetic risk factor for CAD in this Taiwanese population. Perhaps a further study including assessment of vitamin status is needed to better clarify the relationship between MTHFR genotypes and CAD.

The antioxidant effects of quercetin metabolites on the prevention of high glucose-induced apoptosis of human umbilical vein endothelial cells.

Diabetes mellitus is an important risk factor for CVD. A previous study showed that high glucose induced the apoptosis of human umbilical vein endothelial cells (HUVEC) via the sequential activation of reactive oxygen species, Jun N-terminal kinase (JNK) and caspase-3. The apoptosis cascade could be blocked by ascorbic acid at the micromolar concentration (100 microm). In addition to ascorbic acid, quercetin, the most abundant dietary flavonol, has been recently actively studied in vascular protection effects due to its antioxidant effect at low micromolar concentrations (10-50 microm). Quercetin sulfate/glucuronide, the metabolite of quercetin in blood, however, has been rarely evaluated. In the present study, we investigated the effect of quercetin sulfate/glucuronide on the prevention of high glucose-induced apoptosis of HUVEC. HUVEC were treated with media containing high glucose (33 mm) in the presence or absence of ascorbic acid (100 microm) or quercetin sulfate/glucuronide (100 nm, 300 nm and 1 microm). For the detection of apoptosis, a cell death detection ELISA assay was used. The level of intracellular H2O2 was measured by flow cytometry. JNK and caspase-3 were evaluated by a kinase activity assay and Western blot analysis. The results showed that high glucose-induced apoptosis was inhibited by quercetin sulfate/glucuronide in a dose-dependent manner. The effect of quercetin sulfate/glucuronide on H2O2 quenching, inhibition of JNK and caspase-3 activity at the nanomolar concentration (300 nm) was similar to that of ascorbic acid at the micromolar concentration (100 microm). The findings of the present study may shed light on the pharmacological application of quercetin in CVD.

Effect of short-term vitamin (folic acid, vitamins B6 and B12) administration on endothelial dysfunction induced by post-Methionine load hyperhomocysteinemia

This study showed that short-term vitamin administration effectively reduced post-methionine load homocysteine levels and thereby ameliorated endothelium-dependent flow-mediated vasodilation in 16 healthy adults. Post-methionine load homocysteine levels decreased from 22.7+/-3.8 to 17.0+/-2.1 micromol/L (p <0.001), and flow-mediated vasodilation after methionine load increased from 8.6+/-3.6% to 13.8+/-2.9% (p <0.001) after vitamin administration.

Time-dependent benefit of initial thrombosuction on myocardial reperfusion in primary percutaneous coronary intervention

Background:  In ST‐segment elevation acute myocardial infarction (STEMI), dislodgement of thrombus within the culprit artery during primary percutaneous coronary intervention (PCI) may cause distal embolisation and impaired myocardial reperfusion. Clinical results of thromboembolic protection strategies have been controversial. We conducted this study to investigate whether the benefit of thrombus removal is time dependent.

Neurocognitive Improvement After Carotid Artery Stenting in Patients With Chronic Internal Carotid Artery Occlusion and Cerebral Ischemia

Background and Purpose— Chronic cerebral hypoperfusion may lead to impairment in neurocognitive performance in patients with chronic internal carotid artery occlusion, and the effects of carotid artery stenting on neurocognitive function have been unclear. Methods— We prospectively enrolled 20 chronic internal carotid artery occlusion patients with objective ipsilateral hemisphere ischemia, in whom carotid artery stenting was attempted. Functional assessments, including the National Institutes of Health Stroke Scale, Barthel Index, and a battery of neuropsychological tests, including the Mini-Mental State Examination, Alzheimer Disease Assessment Scale–Cognitive Subtest, verbal fluency, and Color Trail Making A and B, were administered before and 3 months after intervention. Results— Successful recanalization was achieved in 12 of 20 patients (60%). There was no procedural or new cerebral ischemic event, except for 1 intracranial hemorrhage, which occurred during the procedure and had neurologic sequelae; this case was excluded from analysis. The demographics and baseline cognitive performance were similar between the group with a successful outcome (group 1, n=12) and patients who did not (group 2, n=7). Ten of 12 patients in group 1 had improvement in ipsilateral brain perfusion after the procedure, but none in group 2 had improvement. Significant improvement in the scores on the Alzheimer Disease Assessment Scale–Cognitive Subtest (before, 7.7±8.9 versus after, 5.7±7.1; P=0.024), Mini-Mental State Examination (before, 25.8±3.8 versus after, 27.7±2.7; P=0.015), and Color Trail Making A (before, 123.2±68.6 versus after, 99.3±51.5; P=0.017) were found in group 1 but not in group 2. Conclusions— Successful carotid artery stenting improves global cognitive function as well as attention and psychomotor processing speed in patients with chronic internal carotid artery occlusion.

The application of infrared thermography in evaluation of patients at high risk for lower extremity peripheral arterial disease

OBJECTIVE We investigated the usefulness of infrared thermography in evaluating patients at high risk for lower extremity peripheral arterial disease (PAD), including severity, functional capacity, and quality of life. METHODS A total of 51 patients (23 males; age 70 ± 9.8 years) were recruited. They completed three PAD-associated questionnaires, including walking impairment, vascular quality of life, and 7-day physical activity recall questionnaires before a 6-minute walking test (6MWT). Ankle-brachial index (ABI) and segmental pressure were analyzed for PAD diagnosis and stenotic level assessment. The cutaneous temperature at shin and sole were recorded by infrared thermography before and after the walk test. Detailed demographic information and medication list were obtained. RESULTS Twenty-eight subjects had abnormal ABI (ABI <1), while PAD was diagnosed in 20. No subjects had non-compressible artery (ABI >1.3). Demographic profiles and clinical parameters in PAD and non-PAD patients were similar, except for age, smoking history, and hyperlipidemia. PAD patients walked shorter distances (356 ± 102 m vs 218 ± 92 m; P < .001). Claudication occurred in 14 patients, while seven failed in completing the 6MWT. The rest temperatures were similar in PAD and non-PAD patients. However, the post-exercise temperature dropped in the lower extremities with arterial stenosis, but was maintained or elevated slightly in the extremities with patent arteries (temperature changes at sole in PAD vs non-PAD patients: -1.25 vs -0.15°C; P < .001). The exercise-induced temperature changes at the sole were not only positively correlated with the 6MWD (Spearman correlation coefficient = 0.31, P = .03), but was also correlated with ABI (Spearman correlation coefficient = 0.48, P < .001) and 7-day physical activity recall scores (Spearman correlation coefficient = 0.30, P = .033). CONCLUSION By detecting cutaneous temperature changes in the lower extremities, infrared thermography offers another non-invasive, contrast-free option in PAD evaluation and functional assessment.

Impairment of Cerebrovascular Reactivity by Methionine-Induced Hyperhomocysteinemia and Amelioration by Quinapril Treatment

Background and Purpose Human studies have shown that methionine-induced hyperhomocysteinemia impairs brachial artery endothelial function via decreasing nitric oxide activity. However, the effect of homocysteine on cerebrovascular reactivity (CVR), which has been reported to be nitric oxide related in experimental and animal studies, remains unclear in humans. Inhibition of angiotensin-converting enzyme may improve nitric oxide–mediated cerebral as well as peripheral endothelial function. The aim of the present study was to investigate the effect of methionine-induced hyperhomocysteinemia on CVR before and after treatment with quinapril, an angiotensin-converting enzyme inhibitor, in healthy adults. Methods Plasma homocysteine and CVR were measured at baseline and 4 hours after methionine load (0.1 g/kg body wt) before and after quinapril treatment (10 mg/d for 1 week) in both younger and older groups. CVR was assessed by transcranial Doppler ultrasonography, measuring the percent increase of flow velocity in the middle cerebral artery after brief carotid compression (expressed as transient hyperemic response ratio [THRR]). Results Homocysteine levels were significantly increased after methionine load either before or after quinapril treatment in both groups. Before quinapril treatment, postmethionine THRR was preserved in younger adults (24.2±5.3% versus 23.8±6.3% at baseline, P =0.73) and decreased in older adults (12.9±2.2% versus 21.8±4.0% at baseline, P <0.001). After quinapril treatment, postmethionine THRR was preserved in both groups (24.5±5.9% versus 24.0±5.0% at baseline, P =0.42 in younger adults; 20.4±3.9% versus 21.3±3.3% at baseline, P =0.35 in older adults). Conclusions Our study suggests that methionine-induced hyperhomocysteinemia may be causally associated with impairment of CVR in older normal subjects.

Carotid stenting improves cognitive function in asymptomatic cerebral ischemia

OBJECTIVES Asymptomatic critical internal carotid artery (ICA) stenosis may lead to cognitive impairment. Carotid stenting (CS) may improve cerebral perfusion, but its impact on neuro-cognitive function has been controversial. METHODS We prospectively enrolled 34 asymptomatic patients with unilateral ICA stenosis or occlusion, in whom CS was attempted. Computed tomography cerebral perfusion (CTP), and functional assessments including National Institutes of Health Stoke Scale (NIHSS), Bathel Index (BI), and a battery of neuropsychological tests including Mini-Mental State Examination (MMSE), Alzheimer Disease Assessment Scale-Cognitive Subtest (ADAS-Cog), verbal fluency, and Color Trail Making A and B, were done prior to and 3 months after the procedure. RESULTS Successful CS was achieved in 28 of 34 patients (82%). Based on the baseline CTP finding and intervention result, patients were divided into three groups: group I (n=6) as ipsilateral cerebral ischemia with failed CS procedure, group II (n=17) as ipsilateral cerebral ischemia with successful CS procedure, and group III (n=11) as normal baseline CTP with successful CS procedure. The demographics and baseline cognitive performances were similar among the three groups. In group II, there were significant improvement in Alzheimer Disease Assessment Scale (pre 6.8 ± 4.3 vs post 4.9 ± 2.8, p=0.033), Mini-Mental State Examination Score (pre 25.8 ± 3.8 vs post 27.4 ± 3.5, p=0.007), and Color Trail test A (pre 120.4 ± 73.9s vs post 95.8 ± 57.6s, p=0.004) after CS. In groups I and III, however, no significant difference was observed in any of the cognitive tests. CONCLUSIONS Successful CS improves neurocognitive function in asymptomatic ICA stenosis or occlusion with objective ipsilateral ischemia.