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Biomedical subjects

W H Pan

Publications and source records attributed to W H Pan.

At least 37 records · Page 2Linked to original sources

Community-based molecular epidemiology of HTLV type I in Taiwan and Kinmen: implication of the origin of the cosmopolitan subtype in northeast Asia.

To understand the possible origin and dissemination of HTLV-I infection in northeast Asia, community-based molecular epidemiological studies were conducted on the Kinmen Islands (off the coast of Fukien Province, China) and in Taiwan. A total of 3831 Taiwanese from 3 townships (Pu-Li, Chu-Dung, and Pu-Tze) and 993 aborigines from 4 tribes in Taiwan participated in this study. The prevalence rates of HTLV-I infection in adult residents from Pu-Li, Chu-Dung, and Pu-Tze were 0.82, 1.72, and 1.63%, respectively. None of the aborigines had HTLV-I infection. Previously, 0.73% of the adult population of Kin-Hu, Kinmen were found to have HTLV-I infection. Peripheral blood mononuclear cells were collected from HTLV-I carriers identified both in Taiwan and Kinmen and the HTLV-I LTR sequences were PCR amplified, subcloned, and sequenced for phylogenetic tree analysis. The results showed that all 6 HTLV-I isolates from Kinmen and 13 of 18 (72.2%) isolates from Taiwan were group a (transcontinental) of Cosmopolitan subtype, while 5 of 18 (27.8%) isolates from Taiwan were group b (Japanese) of Cosmopolitan subtype. Since all of the HTLV-I-infected persons were descendants of immigrants from mainland China, the origin of the Cosmopolitan subtype in Taiwan and Kinmen may not have been Japan, as previously theorized, but China, possibly the result of the migration of an infected population in the past several centuries.

Adult↗

Coronary heart disease mortality trends in men in the post World War II birth cohorts aged 35-44 in Japan, South Korea and Taiwan compared with the United States.

BACKGROUND: Since World War II, people in Japan, South Korea, and Taiwan have been exposed to a westernized lifestyle. It is most likely that the post World War II cohorts (1950+) have been more exposed. We hypothesize that there would be an increase in mortality from coronary heart disease (CHD) in men aged 35-44 in these countries. METHODS AND RESULTS: Mortality from CHD in men aged 35-44 in South Korea and Taiwan has recently increased, and in Japan it has decreased. Mortality from CHD in men aged 35-44 is lower in Japan than in either South Korea or Taiwan, and much lower than in the US. National sample data and several epidemiological studies have shown that risk factors for CHD including hypercholesterolaemia and hypertension in the past decade were not much different between young adult men in Japan and the US. Based upon these risk factors, CHD death rates among post World War II cohorts should be similar in Japan and the US. However, the rates are five times higher in the US for men aged 35-44. The majority of deaths in the category of diseases of the heart were from heart failure in men in this age group in Japan; the mortality from heart failure was about three times higher than the mortality from CHD. Heart failure was rarely used in men aged 35-44 in the US. CONCLUSIONS: The continued low mortality rates from CHD in young men in Japan may be an artifact. It is possible that CHD death rates in post World War II birth cohort in Japan are similar to US rates.

Adult↗

Relationship between hemostatic factors and known cardiovascular disease correlates in two suburban populations in Taiwan.

The Cardiovascular Disease (CVD) Risk Factor Two-Township Study is a longitudinal cardiovascular epidemiologic study of two suburban towns in Taiwan. Analyzing baseline data from 1,080 men and 1,510 women aged 18 and above, this paper focuses on the relationship of several hemostatic factors to CVD correlates: blood lipids, apolipoproteins, glucose, and uric acid, and blood pressure. Information on these relationships can shed light on whether hemostatic factors contribute to the pathogenesis of CVD independently or through known mechanisms. Pearson correlation and multiple regression analysis were used to analyze the data. In the population studied, cholesterol, and apolipoprotein B had the strongest correlations with all hemostatic factors tested. Triglyceride was also strongly associated with factor VIIc. Factor VIIIc, factor VIIc, and fibrinogen, ordered by the strength of the correlation, were positively and significantly correlated with glucose, uric acid, and blood pressure levels. The associations of apolipoprotein B and cholesterol with fibrinogen (p = 0.14-0.20) were not as strong as those with factors VIIc (p = 0.28-0.37) and VIIIc (p = 0.15-0.30). Factors VIIc and VIIIc were independently associated with most clinical variables studied, including the levels of cholesterol components, triglyceride, glucose, uric acid, and diastolic blood pressure. These finding indicate that states of coagulating factors correlated, to varied degrees, with levels of blood lipid parameters, uric acid, and blood pressure in the population studied.

Apolipoproteins↗

Striatal glutamate release is important for development of ischemic damage to striatal neurons during rat heatstroke.

This study attempted to ascertain whether heatstroke-induced ischemia is associated with augmented striatal glutamate release and can be attenuated by NMDA receptor antagonists. Mean arterial pressure (MAP), striatal cerebral blood flow (CBF), striatal glutamate release and striatal neuronal damage score were assessed in saline-treated rats and in rats treated with NMDA receptor antagonists. Heatstroke was induced by exposing the animals to a high ambient temperature; the moment at which MAP and CBF began to decrease from their peak levels was taken as the onset of heatstroke. During onset of heatstroke, rats displayed higher values of colonic temperature, striatal glutamate release and striatal neuronal damage score, and lower values of MAP and striatal blood flow compared with normothermic control rats. The decreased MAP, the diminished striatal blood flow, the augmented striatal glutamate release and the increased striatal neuronal damage score during onset of heatstroke were significantly attenuated by pretreatment with an NMDA receptor antagonist such as MK-801 or ketamine. In addition, the survival time (interval between onset of heatstroke and death) of the rats was extended by pretreatment with one of these two NMDA receptor antagonists. These results suggest that marked accumulation of glutamate in the striatum is important for the development of ischemic damage to striatal neurons during the onset of heatstroke.

Animals↗

Reference spirometric values in healthy Chinese neversmokers in two townships of Taiwan.

The present community-based study was performed to provide predictive equations and lower boundaries of normal values for forced expiratory volume in one second (FEVI), forced vital capacity (FVC), and their percent ratio (FEV1%) in non-smoking, healthy adult men and women residing in communities, using ATS-recommended techniques and equipment. Use was made of data collected cross-sectionally from Nov. 1990 to Dec. 1993 in an ongoing longitudinal study on evolution of cardiovascular disease risk factors in Chinese. The spirometric values in our population reached their peak at around age 20. After age 20, a downward age trend was observed for FVC, FEV1, and FEV1%. Linear and negative relations were found in adults for each of the three spirometric values with age. Linear and positive relations were found between height and FVC or FEV1, but not between height and FEV1%. The age trends of FVC and FEV1 in Chinese adults were similar to those in Caucasians. Mean FVC and FEV1 levels of Chinese in Taiwan were systematically lower than those of Caucasians for a given height and a given age. Age and height specific percentile values of FVC and FEV1 and the age-specific percentile value of FEV1% are provided for adult men and women in this community study.

Adult↗

Effects of different perfusion medium on the extracellular basal concentration of dopamine in striatum and medial prefrontal cortex: a zero-net flux microdialysis study.

The zero-net flux microdialysis method was used to determine (1) the basal concentration of dopamine (DA) in the extracellular space, and (2) the in vivo recovery of Da in the striatum and the medial prefrontal cortex by using three different kinds of perfusion medium. They were, (a) commercial Ringer's solution, (b) low Ca2+ Ringer's solution, and (c) artificial cerebrospinal fluid (aCSF). Our results not only support previous findings that the high Ca2+ concentration in the perfusion medium could increase the baseline concentration of DA in the dialysate, which was collected from extracellular space through dialysis probe; but also provides evidence that this baseline increase was primarily due to an increase of basal DA concentration, and not from the increase of the in vivo recovery. Additionally, there was no significant difference in the basal DA concentration by using either commercial Ringer's solution or aCSF. This indicates that both commercial Ringer's solution and aCSF are suitable as good perfusion medium to determine the basal DA in the rat's brain.

Animals↗

Incidence of NIDDM and the effects of gender, obesity and hyperinsulinaemia in Taiwan.

Our aim is to determine non-insulin-dependent diabetes mellitus (NIDDM) incidence in Taiwan and examine its relation to obesity and hyperinsulinaemia in Chinese men and women. A total of 995 men and 1195 women aged 35-74 years free from diabetes in two townships in Taiwan were followed up with a second examination. At baseline general and metabolic data were recorded, and detailed anthropometric parameters and plasma glucose and insulin were assessed. World Health Organisation (WHO) criteria of fasting glucose 7.8 mmol/l or greater was utilized for defining diabetes. The age-standardized incidence rate based on the United States population in 1970 was 9.3/1000 (CI 5.8-12.8) in men and 9.3/1000 (CI 6.2-12.4) in women and the based on the WHO population in 1976 was 8.9/1000 (CI .5-12.3) in men and 8.9/1000 (CI 5.9-11.9) in women for the Chinese who had a mean BMI slightly greater than 24 (kg/m2). The predictability of the plasma glucose level was greater than that of the insulin level and the obesity indices. NIDDM incidence increased approximately threefold with each 0.67 mmol/l increase in plasma glucose level in men and women. The present study demonstrated the essential relationship of not only BMI but also central obesity indices (such as subscapular and waist circumference) to the incidence of NIDDM among men and women and a stronger relationship between NIDDM incidence and obesity in women than in men. The predictive effects of obesity indices and fasting plasma insulin values on NIDDM risk were independent of each other in men. Obesity and hyperinsulinaemia each without the presence of the other can lead to an increased risk of NIDDM. In women the NIDDM incidence increased more than additively in those with both obesity and hyperinsulinaemia compared to those with single obesity or hyperinsulinaemia. A slightly higher incidence of NIDDM in Taiwan than in western countries was found. The importance of obesity is indicated for predicting NIDDM in the community. Hyperinsulinaemia was found to play a significant role in predicting NIDDM incidence independent of obesity in men and synergistically with obesity in women.

Adult↗

Associations between carotid atherosclerosis and high factor VIII activity, dyslipidemia, and hypertension.

BACKGROUND AND PURPOSE: A subsample of 147 Chinese subjects from a population-based study of cardiovascular diseases (Cardiovascular Disease Risk Factor Two-Township Study) participated in an ancillary study on extracranial carotid color duplex ultrasonography that aimed to assess the relations of coagulation factors to stroke and carotid atherosclerosis. METHODS: Logistic models were used to study the associations between cardiovascular disease risk factors and stroke/carotid atherosclerosis, controlling for the effects of age and sex. RESULTS: Stroke was significantly associated with hypertension and high values of plasma glucose but not with fibrinogen, factor VIIc, or factor VIIIc. Carotid plaques identified in this study were mostly mild and moderate. The presence of these mild and moderate carotid plaques was significantly associated with high values of factor VIII activity, hypercholesterolemia, hypertriglyceridemia, and hypertension. The highest tertile of factor VIIIc (> 1.53) was associated with an odds ratio of 3.35 for carotid atherosclerosis when compared with the lowest tertile (< 1.20). A multiple logistic regression including all significant risk factors showed that the degree of association between factor VIIIc and atherosclerosis was attenuated to an odds ratio of 2.65 (P = .061). CONCLUSIONS: In the present study, the roles of hypertension, hypercholesterolemia, and hypertriglyceridemia have been implicated in the pathogenesis of carotid atherosclerosis, and roles for hypertension and hyperglycemia in stroke were indicated. A positive association between factor VIIIc and carotid atherosclerosis in this Chinese population was found. Whether this association is independent of the effect of other cardiovascular risk factors awaits further study.

Adult↗

Intrategmental infusion of cocaine decreases dopamine release and enhances norepinephrine release in the medial prefrontal cortex.

We evaluated the effects of local cocaine infusion into the A10 (ventral tegmental area), the cell body of the mesocorticolimbic dopaminergic pathway, on the extracellular concentrations of dopamine and norepinephrine in the medial prefrontal cortex, one of its terminal fields. A 1-ml Hamilton syringe was used to infuse a cocaine solution, either 20 or 200 microM, into the ventral tegmental area of anesthetized rats for 120 min through a microdialysis probe. The pure artificial cerebrospinal fluid (0 microM cocaine) infusion served as a control and a lidocaine (100 microM) infusion was administered to prevent the local anesthetic effect of cocaine. After intrategmental cocaine infusion (either 20 or 200 microM), extracellular dopamine and norepinephrine in the ventral tegmental area both increased significantly to a steady state level (208 +/- 42 and 148 +/- 23% for low dose and 220 +/- 24 and 150 +/- 15% for high dose). Simultaneously, the 200-microM cocaine infusion caused a significant decrease in extracellular dopamine (77 +/- 5%) but an increase in norepinephrine (140 +/- 6%) in the medial prefrontal cortex. The local anesthetic, lidocaine, produced no effects on the dopamine or norepinephrine output (neither in the ventral tegmental area nor in the medial prefrontal cortex). This study not only supports recent findings of an increase in extracellular dopamine and norepinephrine in the ventral tegmental area on intrategmental cocaine infusion, but also demonstrates that cocaine infused locally in the ventral tegmental area can decrease dopamine and increase norepinephrine at a remote terminal area (medial prefrontal cortex). Finally, the introduction rate of cocaine into the ventral tegmental area by retrograde microdialysis was found to be 0.83 ng/min for the low dose and 8.14 ng/min for the high dose.

Anesthetics, Local↗

Initial rate and equilibrium isotope exchange studies on the ATP-dependent activity of polyphosphate Glucokinase from Propionibacterium shermanii.

Polyphosphate glucokinase [EC 2.7.1.63] catalyzes the phosphorylation of glucose using either inorganic polyphosphate [poly(P)] or ATP as the phosphoryl donor. Both activities purified from Propionibacterium shermanii are the functional properties of a single enzyme with separate binding sites for the two phosphoryl donor substrates. The enzyme was found to utilize poly(P) much more efficiently than it does ATP, with a kcat/Kpoly(P) to kcat/KATP ratio of 2800. The catalytic constant for poly(P) is about 2-fold higher than for ATP. Other nucleotides like GTP and dATP also served as substrates with good efficiencies. The ATP-dependent reaction was analyzed using steady-state kinetics and isotopic exchange kinetics at chemical equilibrium. Intersecting initial velocity patterns for both glucose and ATP indicate sequential addition of substrates. Product inhibition studies resulted in two competitive and two noncompetitive patterns, which is characteristic of a Theorell-Chance mechanism or a random mechanism with two dead-end complexes. Results of isotope exchange experiments, however, rule out a Theorell-Chance mechanism, as well as a truly random mechanism. They are not consistent with a partially random mechanism (although a kinetically compulsory order of substrate binding is not excluded), where glucose is preferentially bound to free enzyme before ATP, and ADP is preferentially released as the first product, followed by glucose 6-phosphate. Dead-end inhibition analysis confirms this order of substrate binding. Competitive inhibition of ADP vs ATP is explained as resulting primarily from binding as a dead-end inhibitor (E.Glc.ADP) and not as a product. Another weaker abortive complex, E.ATP.G6P, is also formed. The chemical transformation or the release of ADP is the rate-limiting step in ATP utilization.

Adenosine Diphosphate↗

Sexual differences in bone markers and bone mineral density of normal Chinese.

We measured bone mineral density (BMD) at lumbar (L2-L4) vertebrae and proximal femurs of 385 healthy Chinese women aged 40-70 years and 156 healthy Chinese men aged 20-85, and four markers-bone alkaline phosphatase isozyme (BAP), procollagen-I C terminal propeptide (PICP), osteocalcin (BGP) in serum, and a bone resorption marker, urinary cross-linked N-telopeptide of type I collagen (NTX), of these subjects. The results indicate that in postmenopausal women, levels of all the markers increased with age. In men, serum BAP, PICP, and urinary NTX decreased significantly, and serum BGP decreased with borderline significance (P = 0.08). With increasing age, bone density decreased at both sites in postmenopausal women and at the proximal femur in men. The lumbar bone density showed no significant age-related changes in men. In premenopausal women, BMD at either site showed no significant change with increasing age. Despite the different trends between men and women of age-related changes in BMD and bone markers, bone density of both proximal femur and spine in both sexes correlated inversely with levels of the bone markers in a manner independent of age or body weight. The meaning of opposite age effects on bone markers in men and women needs further investigation. In addition, higher bone marker levels, implying faster bone turnover rate, are associated with lower BMD in both sexes.

Adult↗

Thrombophilia in patients with hypercholesterolemia.

To investigate a possible interrelationship between hypercholesterolemia and the coagulation and fibrinolytic system, the Cardiovascular Disease Risk Factor Two-Township Study in Taiwan was undertaken as a longitudinal prospective study focusing on the evolution of cardiovascular disease risk factors, with an emphasis on hemostatic factors. Hemostatic parameters measured in this study included prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, factor VIIc, factor VIIIc, antithrombin III, and plasminogen. Subjects of both sexes with hypercholesterolemia (> 6.2 mmol/L) also had significant elevations of diastolic blood pressure, plasma glucose, triglycerides, fibrinogen, and factor VIIc and reduced PT and APTT compared with subjects with lower cholesterol. The hypercholesterolemic women additionally had significant elevations of systolic blood pressure and factor VIIc. Levels of the anticoagulant factors, antithrombin III and plasminogen, were also higher in both hypercholesterolemic men and women. In men, only factor VIIIc had no statistically significant elevation. In women, only PT showed no statistical difference. Established coronary risk factors such as fibrinogen and factor VIIc showed remarkable elevations in patients of both sexes. Using Pearson correlation and multiple regression, the most significant parameter related to cholesterol level was factor VIIc. The present results show that hemostatic abnormalities do exist in patients with hypercholesterolemia, and this thrombophilic phenomenon sheds further light on the study of higher cardiovascular mortality in these subjects.

Blood Pressure↗

A new video path analyzer to monitor travel distance, rearing, and stereotypic movement of rats.

A new video path analyzer, described herein, monitors travel distance, rearing, stereotypic movement, rotation, and speed of rats simultaneously. The video path analyzer was equipped with a cage (black background, 50 cm long x 50 cm wide x 50 cm high), camera, television screen, computer, and printer. A detailed description of this equipment is included. While studying the known activating effects of d-amphetamine on rats' behavior, we also evaluated the equipment for its maximum and accurate contribution to this study. Results indicate that this equipment compared to photocell equipment produced reliable data and offered the advantages of lower cost. It is expected to gain more popularity in the near future.

Animals↗

Bone mineral density and bone markers in relation to vitamin D receptor gene polymorphisms in Chinese men and women.

Whether vitamin D receptor gene (VDRG) polymorphism can be used as a predictor for bone turnover rate or bone mass remains controversial. Its role within various ethnic populations are also unsettled. We examined VDRG polymorphism using restrictive enzymes Bsm-I, Apa-I, and Taq-I in 155 men aged 22-88 and 113 premenopausal women aged 40-53. The bone mineral density (BMD) of the vertebrae (L2-4), proximal femur, and total body bone mineral content (tb-BMC) (women only), as well as urinary N-terminal crosslinked fragment of type I collagen (NTX), serum osteocalcin, bone isozyme of alkaline phosphatase, and caboxyterminal propeptide of type I procollagen levels were measured. Chinese men and women exhibited a low prevalence for B (absence of Bsm-I restriction site) phenotypes than white and Japanese. Within the tested samples there were 0.4% BB homozygotes, 6.7% Bb heterozygotes, and 93% bb homozygotes. The distributions of Apa-I polymorphism (9.0% AA, 42.5% Aa, and 48.5% aa) also differed from those reported for the white populations. Most of the Chinese men and women were TT homozygous (96.6%). A comparison of actual values and values adjusted for age and weight of tb-BMC and BMD at the lumbar spine, Trochanter, Ward's triangle, and femoral neck showed no significant difference among three subgroups in each of the three sets of polymorphism. Furthermore, the actual values and adjusted values (adjusted for age) of the four bone markers, respectively, showed no significant differences. We conclude that given the very low prevalence of the suspected high risk genotypes (B, A, and t), and the lack of difference among the polymorphic subgroups, VDRG polymorphism may not be an important determinant of the bone turnover rate and bone mass of Chinese men and women.

Adult↗

Beneficial effects of pravastatin on fasting hyperinsulinemia in elderly hypertensive hypercholesterolemic subjects.

We undertook this prospective double-blind, placebo-controlled study to evaluate the efficacy and safety of low-dose (15 mg) pravastatin in elderly hypercholesterolemic hypertensive subjects with concurrent antihypertensive treatment and to determine whether fasting hyperinsulinemia could also be improved. At three hypertension and lipid clinics of two medical centers, 96 elderly (49 women, 47 men) ambulatory subjects were randomized to active treatment or placebo for 12 months after a 3-month single-blind lead-in period. Hypertensive subjects with plasma total cholesterol levels of at least 6.47 mmol/L (250 mg/dL) and triglyceride levels less than 3.39 mmol/L (300 mg/dL) were treated with 15 mg pravastatin for 12 months after receiving 3 months of the American Heart Association step I diet. Lipid, glucose, and fasting insulin levels were measured; clinical laboratory tests included liver function and creatine kinase determinations. After 12 months of pravastatin therapy, plasma total cholesterol concentration decreased by 25.1% (from a mean of 7.29 to 5.47 mmol/L, P < .05), low-density lipoprotein cholesterol decreased by 30.2% (from 5.27 to 3.68 mmol/L, P < .05), and triglycerides decreased by 10.7% (from 1.68 to 1.50 mmol/L, P < .05). High-density lipoprotein cholesterol increased by 9.2% (from 1.20 to 1.31 mmol/L, P < .05). Fasting insulin levels decreased from 89.0 to 61.5 pmol/L (P < .05). All of these changes were greater (P < .05) than any tendency toward change in the placebo group. Adverse events and clinical laboratory abnormalities were generally mild and transient in both placebo and pravastatin groups. Study drugs were withdrawn from one subject in each group with asymptomatic creatine kinase elevations. We conclude that low-dose pravastatin was effective and safe in the treatment of hypercholesterolemic hypertensive subjects on concurrent antihypertensive therapy. It also improved fasting hyperinsulinemia despite the use of beta-blockers and diuretics in these hypertensive subjects.

Aged↗

Locally application of amphetamine into the ventral tegmental area enhances dopamine release in the nucleus accumbens and the medial prefrontal cortex through noradrenergic neurotransmission.

The effects and mechanisms of locally applied d-amphetamine (AMPH) into the ventral tegmental area (VTA) on extracellular dopamine (DA) concentrations in both the nucleus accumbens (N ACC) and the medial prefrontal cortex (mPFC) were investigated. A solution containing either, 0, 100, 500 or 1000 microM AMPH was infused, using a 1-ml Hamilton syringe, into the VTA of chloral hydrate-anesthetized rats for 100 min through a microdialysis probe. Infusion of AMPH into the VTA dose-dependently increased extracellular DA in the N ACC and in the mPFC. The introductory rate of AMPH application through the dialysis probe into the VTA was estimated simultaneously. Local infusion of either a selective alpha adrenoceptor antagonist (phentolamine, 1 and 10 microM) or a selective beta adrenoceptor antagonist (alprenolol, 1 and 10 nM) dose-dependently blunted the intra-VTA AMPH-induced extracellular DA increase in the N ACC. Further, local infusion of phentolamine (0.1 and 1 microM) and alprenolol (1 and 10 nM) appreciably and dose-dependently reduced the effects of AMPH on the DA increase in the mPFC. These results suggest that intra-VTA AMPH can enhance DA release in the N ACC and in the mPFC by activating noradrenergic neurotransmission in the VTA.

Amphetamine↗

The reallocation of body fat toward the abdomen persists to very old age, while body mass index declines after middle age in Chinese.

OBJECTIVES: Age-specific distributions of several anthropometric measurements were examined to elucidate age-associated changes. DESIGN: Community-based cross-sectional analysis, which was performed on anthropometric data collected from members of 2769 families from November 1991 to September 1993. SUBJECTS: 2776 Chinese men and 3176 non-pregnant Chinese women. MEASUREMENTS: Age-specific values of several obesity indices, including a general obesity index (body mass index) and obesity indices at various parts of the body, including waist-to-hip ratio, waist circumference, hip circumference, arm circumference, triceps skinfold thickness and subscapular skinfold thickness. RESULTS: The age-specific percentile values of weight, body mass index, arm circumference, triceps skinfold thickness, subscapular skinfold thickness and hip circumference showed a gradual increase with age up to middle age, but a decline subsequently. This 'up and then down' phenomenon occurred later in women than in men. On the other hand, age-specific percentile values of waist circumference and waist-to-hip ratio showed a steady increase with age from early life. CONCLUSIONS: These data indicate that, in very old age, a greater amount of fat tends to accumulate in the abdominal region compared to the deposition in the younger age groups. This occurs despite a decrease in body weight and body mass index after middle age.

Abdomen↗

Values of blood coagulating factors vary with ambient temperature: the Cardiovascular Disease Risk Factor Two-Township Study in Taiwan.

Seasonal influence on mortality from cardiovascular and cerebrovascular diseases is well documented. Understanding the seasonal variations in cardiovascular risk factors can shed light on this phenomenon. Elevation of coagulation factors during cold weather may in part explain the higher mortality from myocardial infarction and stroke in winter. The Cardiovascular Disease Risk Factors Community Study (CVDFACTS) included subjects belonging to 2 cohorts located in northern and southern Taiwan. This study included 2877 subjects aged 18 and above whose blood levels were examined for various coagulating factors. Besides measuring conventional cardiovascular risk factors including: blood pressure, body mass index and total cholesterol, values for blood fibrinogen, factor VII activity, factor VIII activity, plasminogen, antithrombin III, prothrombin time and activated partial thromboplastin time were determined for all subjects. Of these hemostatic parameters, levels of all, except prothrombin time, were statistically different between days with mean temperature > 20 degrees C and days with temperature < or = 20 degrees C (P < 0.01). In cold weather, a greater tendency to clot in circulatory system was demonstrated in this study, indicating seasonal variations may be demonstrated in this subtropical region.

Adult↗