Biomedical subjects

Chi-Tzong Hong

Publications and source records attributed to Chi-Tzong Hong.

6 recordsLinked to original sources

PubMed2006

Effects of arsenic exposure and genetic polymorphisms of p53, glutathione S-transferase M1, T1, and P1 on the risk of carotid atherosclerosis in Taiwan.

To evaluate the joint effects between genetic polymorphisms of glutathione S-transferase M1, T1, P1, and p53, and arsenic exposure through drinking well water on the risk of carotid atherosclerosis, 605 residents including 289 men and 316 women were recruited from a northeastern area of Taiwan. Carotid atherosclerosis was diagnosed by either a carotid artery intima-media thickness (IMT) of >1.0 mm, a plaque score of > or =1, or stenosis of >50%. A significant age- and gender-adjusted odds ratio of 3.3 for the development of carotid atherosclerosis was observed among the high-arsenic exposure group who drank well water containing arsenic at levels >50 microg/L. The high-arsenic exposure group with GSTP1 variant genotypes of Ile/Val and Val/Val, and with the p53 variant genotypes of Arg/Pro and Pro/Pro had 6.0- and 3.1-fold higher risks of carotid atherosclerosis, respectively. In addition, the high-arsenic exposure group with one or two variant genotypes of GSTP1 and p53 had 2.8- and 6.1-fold higher risks of carotid atherosclerosis, respectively, and showed a dose-dependent relationship. A multivariate-adjusted odds ratio of 3.4 for the risk of carotid atherosclerosis among study subjects with the two variant genotypes of GSTP1 and p53 was also found. Our study showed the joint effects on the risk of carotid atherosclerosis between the genetic polymorphisms of GSTP1 and p53, and arsenic exposure.

Age Factors↗

PubMed2006

Effect of plasma homocysteine level and urinary monomethylarsonic acid on the risk of arsenic-associated carotid atherosclerosis.

Arsenic-contaminated well water has been shown to increase the risk of atherosclerosis. Because of involving S-adenosylmethionine, homocysteine may modify the risk by interfering with the biomethylation of ingested arsenic. In this study, we assessed the effect of plasma homocysteine level and urinary monomethylarsonic acid (MMA(V)) on the risk of atherosclerosis associated with arsenic. In total, 163 patients with carotid atherosclerosis and 163 controls were studied. Lifetime cumulative arsenic exposure from well water for study subjects was measured as index of arsenic exposure. Homocysteine level was determined by high-performance liquid chromatography (HPLC). Proportion of MMA(V) (MMA%) was calculated by dividing with total arsenic species in urine, including arsenite, arsenate, MMA(V), and dimethylarsinic acid (DMA(V)). Results of multiple linear regression analysis show a positive correlation of plasma homocysteine levels to the cumulative arsenic exposure after controlling for atherosclerosis status and nutritional factors (P < 0.05). This correlation, however, did not change substantially the effect of arsenic exposure on the risk of atherosclerosis as analyzed in a subsequent logistic regression model. Logistic regression analyses also show that elevated plasma homocysteine levels did not confer an independent risk for developing atherosclerosis in the study population. However, the risk of having atherosclerosis was increased to 5.4-fold (95% CI, 2.0-15.0) for the study subjects with high MMA% (> or =16.5%) and high homocysteine levels (> or =12.7 micromol/l) as compared to those with low MMA% (<9.9%) and low homocysteine levels (<12.7 micromol/l). Elevated homocysteinemia may exacerbate the formation of atherosclerosis related to arsenic exposure in individuals with high levels of MMA% in urine.

Age Factors↗

PubMed2006

Inconspicuous visual field defect in anterior choroidal artery territory infarction.

We describe a patient with a right anterior choroidal artery territory infarction and an inconspicuous left visual defect. The anterior choroidal artery is a unique artery of the cerebral circulation. The occlusion of this artery can result in dysfunction of motor, sensory, and visual systems with only rare involvement of higher cortical function. Among symptoms reported, visual abnormalities are the most variable and the least common. However, the visual field abnormality may be overlooked and the incidence underestimated since some patients may not be aware of the problem until uncovered by formal visual field testing.

Aged↗

PubMed2006

[Hormone replacement therapy and cognitive function].

Observational studies have suggested that postmenopausal hormone replacement therapy (HRT) may improve cognitive function, but data from randomized clinical trials have been sparse and inconclusive. The effects of HRT on dementia and mild cognitive impairment were assessed in a subgroup of participants in the Women's Health Initiative Memory Study (WHIMS) (a multicenter, randomized, double-blind, placebo-controlled clinical trial). There were two study arms, one involved 4,532 postmenopausal women who received continuous combined estrogen (conjugated equine estrogens [CEE] plus medroxyprogesterone acetate [MPA]) or placebo, and the other involved 2,947 hysterectomized women randomized to continuous unopposed CEE or placebo. All participants were aged 65 years or older. CEE with or without MPA did not protect against (but substantially increased the risk of) dementia of any cause or cognitive decline. Incidence of probable dementia in the estrogen-alone trial was statistically similar to that in the estrogen plus progestin trial. When data from both trials were pooled, the overall risk for probable dementia was increased by 76% (HR, 1.76; 95% CI, 1.19 to 2.60; P = 0.005). A second report from WHIMS suggested that cognitive decline in women aged 65 years and older was greater in those receiving hormone therapy than in those receiving placebo (HR, 1.25; 95% CI, 0.97-1.60). The WHIMS results clearly indicate that CEE with or without MPA should not be used to prevent dementia or enhance cognition in women older than 65 years.

Alzheimer Disease↗

PubMed2005

Ankle muscle activation during functional reach in hemiparetic and healthy subjects.

OBJECTIVE: To compare the differences of reaching ability and electromyography of ankle muscles between healthy and hemiparetic subjects. DESIGN: This is a cross-sectional control trial. A total of 31 subjects with hemiparesis and 31 age-matched healthy adults meeting our selection criteria participated in this study. Subjects performed forward reach and lateral reach, in random sequence, in a sitting position. The average reaching velocity, reaching distance, and onset time and mean muscle activity of bilateral tibialis anterior and soleus were recorded. RESULTS: Subjects with hemiparesis had slower movement velocity and less reaching distance than that of healthy subjects (P < 0.05). The distance for the lateral reach was shorter than that of the forward reach (P < 0.05). The high correlations between contralateral tibialis anterior and soleus were noted in forward (r = 0.66, P < 0.01) and lateral (r = 0.68, P < 0.01) reaching in healthy subjects, but such correlations were not established in subjects with hemiparesis. Except for the ipsilateral soleus, normalized electromyographic activities (percentage of maximal voluntary isometric contraction) during forward and lateral reach were higher for the hemiparetic subjects than that for the healthy subjects (P < 0.05). CONCLUSION: The functional reach abilities and the ankle electromyographic activity patterns in hemiparetic subjects were significantly different from those of healthy subjects. The muscles in the affected ankle cannot be recruited timely and efficiently for the reaching task, even with relative recovery.

Ankle↗

PubMed2005

Effectiveness of modified constraint-induced movement therapy on upper limb function in stroke subjects.

BACKGROUND AND PURPOSE: Of all stroke survivors, more than 50% are left with motor disabilities. Impairment of upper limb movement is a common motor disability. Constraint-Induced Movement Therapy (CIMT) is an intervention which has been used for the treatment of upper extremity motor disabilities in stroke patients. Although CIMT is an effective intervention, a recent survey revealed that this procedure is viewed with apprehension by many clinicians because of concerns about practicality and resource issues. We developed a modified CIMT that reserves the massed training of the affected arm without any physical restriction of the intact one and then used it on our stroke patients. This study was designed to evaluate the effectiveness of this Modified-Constraint-Induced Movement Therapy (m-CIMT). METHODS: Thirty stroke patients were randomly assigned to either an m-CIMT (n=13) or a control group (n=17). Subjects in the m-CIMT group received a 2-week course of m-CIMT. Outcomes were evaluated using the Wolf Motor Function Test (WMFT). RESULTS: After only 2 weeks of training, significant differences (p<0.05) in favor of m-CIMT were found in the following 6 elements of the WMFT: Extend elbow with weight, Lift pencil, Stack checkers, Flip cards, Turn key in lock, and Lift basket. CONCLUSION: The present study shows that our m-CIMT is useful in improving the function of the affected upper extremity in stroke patients.

Aged↗