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Biomedical subjects

Y A Ding

Publications and source records attributed to Y A Ding.

At least 91 records · Page 5Linked to original sources
PubMed1994

The interrelationship between impaired glucose tolerance and other risk factors for cardiovascular disease: is it a predictor for cardiovascular disease?

Glucose intolerance and cardiovascular risk factors were assessed among 215 subjects aged 27-86 years in Ho-long, Taiwan. An oral glucose tolerance test (OGTT) was normal in 107 subjects, impaired in 41 subjects, and abnormal in 67 subjects (as noninsulin dependent diabetes mellitus, NIDDM). Body fatness, blood pressure, carbohydrate and lipid metabolic factors were examined. One-way ANCOVA was used to compare age- and/or BMI-adjusted differences among these groups. Male subjects with NIDDM and impaired glucose tolerance (IGT) had higher systolic (SBP) and diastolic (DBP) blood pressures, plasma insulin (fasting and 1-hour after OGTT), serum triglycerides (TG), heavier body weight, and larger BMI than normal. IGT subjects were also found to have higher TG, insulin (2-hour) and larger insulin area under curve (IAUC) after OGTT than NIDDM. In females, subjects with NIDDM had higher TG, insulin (fasting and 1-hour after OGTT), and larger IAUC than normal. Moreover, female IGT subjects were also found to have significantly higher SBP, DBP, insulin (1-and 2-hour after OGTT), and larger IAUC than both normal and NIDDM subjects. These results suggest that adverse cardiovascular risk factors are present not only in NIDDM subjects, but also in IGT subjects.

Adult↗
PubMed1994

Are platelet cytosolic free calcium, serotonin concentration and blood viscosity different between hypertensive and normotensive subjects?

In this study, the platelet intracellular calcium and serotonin (5-HT) concentrations as well as the hemorheological properties were compared in 65 hypertensive (HT) and 25 age-matched normotensive (NT) subjects. The result showed that the platelet intracellular calcium concentration in the HT group was significantly higher than in the NT group (165.4 +/- 12.6 vs. 118.9 +/- 12.4 nM, p < 0.05). However, the platelet 5-HT content in the HT group was significantly lower than in the NT group (0.28 +2- 0.03 vs. 0.38 +/- 0.03 nmol/10(8) platelets, p < 0.05). Moreover, red cell flexibility, red cell deformability, hematocrit, fibrinogen concentration and plasma viscosity were all significantly increased in HT subjects. The whole blood viscosity was generally higher in the HT group. In conclusion, the higher platelet intracellular calcium and lower 5-HT level as well as abnormality of hemorheological properties may be important factors in the initiation and perpetuation of hypertension.

Aged↗
PubMed1994

Primary malignant cardiac tumor: an analysis of seven cases.

BACKGROUND: Primary malignant cardiac tumor is a rare disorder which has a myriad of clinical manifestations. It dominates about one-fourth of all cardiac tumors, exhibiting typically malignant histological characteristics and invasive behavior. METHODS: Seven cases of primary malignant cardiac tumor were collected over eight years (1985-1993) in this hospital. Each case had different manifestations. All cases were diagnosed by physical examination, echocardiogram and were subsequently proved by tissue pathology. RESULTS: The majority of these seven cases of primary malignant cardiac tumor had clinical symptoms of chest distress, shortness of breath and paroxysmal nocturnal dyspnea. The relatively young ages of the patients ranged from 11 to 62 years. One case of angiosarcoma, one case of fibrosarcoma, one case of leiomyosarcoma and three cases of lymphoma had the characteristics of cardiac hemodynamic obstruction which was induced by location and size of the tumors in the heart. Five cases of those primary malignant cardiac tumor were mortal; the average life span was nine months following surgical resection and chemotherapy. CONCLUSIONS: From a clinical viewpoint, primary malignant cardiac tumor characteristically displays a rapid downhill course. Death most often occurs from a few weeks to two years after the onset of symptoms. Because these tumors are rare and have a poor clinical outcome, early diagnosis and treatment are vital.

Adult↗
PubMed1994

Effect of intravenous calcitriol on platelet intracellular calcium in uremic hemodialysis patients with secondary hyperparathyroidism.

BACKGROUND: To investigate the effect of the reversal of hyperparathyroidism on platelet intracellular free calcium ([Ca2+]i) by pharmacological parathyroidectomy with intravenous calcitriol in uremic patients with secondary hyperparathyroidism (2 degrees HPT). METHODS: Serum concentrations of intact parathyroid hormone (I-PTH) were measured by two-site immunometric assay, and platelet [Ca2+]i was assessed using the fluorescent indicator fura-2. Fifteen hemodialysis patients with 2 degrees HPT and serum I-PTH 4 times greater than the normal upper limits, were selected for treatment with intravenous calcitriol 1 microgram thrice weekly for one month. RESULTS: An increase of serum I-PTH (449.17 +/- 52.35 vs 32.52 +/- 1.95 pg/ml) and elevated platelet [Ca2+]i (139.49 +/- 8.78 vs 74.70 +/- 6.48 nM/L) was observed in uremic patients with 2 degrees HPT. Serum I-PTH levels were significantly correlated with platelet [Ca2+]i in uremic patients with 2 degrees HPT (r = 0.736, p = 0.002). The serum I-PTH levels decreased from 449.17 +/- 52.35 to 221.27 +/- 35.66 pg/ml (p < 0.001) and platelet [Ca2+]i fell from 139.49 +/- 8.78 to 97.86 +/- 7.25 nM/L (p < 0.001) after treatment. Fall in platelet [Ca2+]i was related to concomitant reduction in PTH levels (r = 0.572, p = 0.026). CONCLUSIONS: It was concluded that an increase in cytosolic calcium in uremia may be at least in part induced by PTH. Besides, intravenous calcitriol can provide an effective way to suppress elevated serum I-PTH and attenuate platelet free calcium in uremia with 2 degrees HPT.

Adult↗
PubMed1994

Effects of long-acting propranolol and verapamil on blood pressure, platelet function, metabolic and rheological properties in hypertension.

The newly developed antihypertensive drugs, the long-acting beta-blocker propranolol and the sustained release calcium antagonist verapamil, are compared in their antihypertensive, platelet function, rheological properties and metabolic effects. The trial was a double-blind, randomised, placebo-controlled cross-over study. Thirty patients with mild to moderate hypertension received propranolol (40-120 mg) or verapamil (80-200 mg) once daily in two separate ten week courses. After ten weeks treatment both drugs had significantly reduced both SBP and DBP. Beta-thromboglobulin (beta-TG) concentration, reflecting the status of platelet activation in vivo, was significantly decreased after propranolol (129.6 +/- 13.5 vs. 77.9 +/- 8.6 ng/ml) and verapamil (129.6 +/- 13.5 vs. 90.7 +/- 10.1 ng/ml) treatments while platelet aggregation induced by ADP, collagen, arachidonic acid or adrenaline and the production of thromboxane B2 (TXB2), 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) and platelet cyclic 3'-5' adenosine monophosphate (C-AMP) concentration were not affected. Significant alterations in rheological parameters such as plasma and whole blood viscosity, fibrinogen level and red cell deformability were not found. Higher cholesterol and low-density lipoprotein-cholesterol (LDL-C) levels were observed after propranolol treatment but not in verapamil treatment. Side-effects were mild, tolerated and no patient had to be withdrawn from the study. In conclusion, propranolol and verapamil are generally effective antihypertensive as well as rheologically safe drugs. Compared with the metabolic effect on serum lipid, verapamil may be a better choice. Both drugs possess the tendency to inhibit platelet properties which is desirable in hypertension treatment.

Adult↗
PubMed1994

Hyperparathyroidism, glucose tolerance and platelet intracellular free calcium in chronic renal failure.

Disturbance in the vitamin D/parathyroid hormone (PTH) axis may be important in the pathogenesis of glucose intolerance and insulin resistance in uraemia. To investigate possible relationships between hyperparathyroidism, intracellular free calcium ([Ca2+]i), and glucose tolerance in chronic renal failure, we measured serum intact PTH (I-PTH) by two-site immunometric assay, platelet [Ca2+]i using the fluorescent indicator fura-2, and plasma glucose and insulin after 14 h overnight fast and at 30, 60 and 120 min following a 75 g oral glucose load, in 18 chronic haemodialysis patients with elevated serum I-PTH. Calcitriol (1 microgram) was administered parenterally at the end of each dialysis session for four weeks. This significantly decreased serum I-PTH (p < 0.001) and platelet [Ca2+]i (p < 0.01). Uraemic patients initially showed marked glucose intolerance, with increased area below the glucose curve compared to healthy controls, but after 4 weeks of calcitriol treatment, this effect was significantly decreased, and there was a significant rise in the area under the insulin curve after glucose load. The insulinogenic index also increased significantly after calcitriol treatment. These data suggest that calcitriol treatment of haemodialysis patient with secondary hyperparathyroidism is associated with increased insulin secretion in response to glucose challenge, and that this change is linked to the decrease in intracellular free calcium.

Adult↗
PubMed1994

Comparison of cilazapril and nifedipine retard on ambulatory blood pressure, metabolic, rheological and platelet function in hypertensive patients.

In a 12 week randomised, double-blind study, a total of 31 patients with a sitting DBP of between 95 and 115 mmHg were enrolled for comparison of the antihypertensive, metabolic and antiplatelet effects of the drugs cilazapril and nifedipine retard. A two week placebo treatment was given before either cilazapril (2.5 mg daily) or nifedipine retard (20 mg twice daily) was administered. After four weeks treatment, those patients with a sitting DBP > 90 mmHg were given a doubling of their initial doses for the next six weeks; the others were maintained at their initial doses. All patients received their drugs and reported any adverse effects every other week. Blood was taken for metabolic, rheological and platelet function tests. Ambulatory BP and heart rate were recorded at the start, fourth and tenth weeks of study. At the end of this trial, there was a significant decrease in both SBP and DBP in the cilazapril group (155 +/- 14 to 142 +/- 12 mmHg systolic, P < 0.01; 106 +/- 6 to 95 +/- 5 mmHg diastolic, P < 0.01). In the nifedipine group, there was also a significant decrease in SBP and DBP (161 +/- 18 to 139 +/- 5 mmHg, systolic, P < 0.01; 101 +/- 6 to 88 +/- 9 mmHg diastolic, P < 0.05) but with a significant increase in heart rate (79 +/- 14 to 91 +/- 10 beats/minute, P < 0.05). There were no significant changes in the biochemical or metabolic parameters in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1993

Captopril-induced agranulocytosis: a case report.

Captopril 12.5 mg twice daily was initially administered given to a woman with chronic renal failure and hypertension. Three weeks later, she developed chills, high fever and sore throat. Hemogram showed severe neutropenia; the white cell count showed 600/cu mm; bone marrow aspirate and biopsy revealed a paucity of myeloid series. Antineutrophil antibody was not detected in the serum. The neutrophil counts returned to normal after captopril was discontinued two weeks later. We recommend that the peripheral white blood cell count in patients whom captopril is prescribed must be carefully monitored in the first three months, particularly in those with impaired renal function.

Aged↗
PubMed1993

Effect of felodipine-ER on blood pressure, platelet function, and rheological properties in hypertension.

Twenty patients with mild to moderate hypertension took part in this study consisting of a two-week placebo treatment period, followed by treatment with an extended-release calcium channel blocker, felodipine-ER (5 to 20 mg once daily) for 12 weeks. The study evaluated the effects of felodipine-ER on blood pressure, platelet function and rheological properties in hypertension. Felodipine-ER significantly reduced systolic and diastolic blood pressure without changing heart rate. There was a significant decrease in adenosine diphosphate-induced platelet aggregation and platelet intracellular calcium concentration, but no significant change in plasma thromboxane B2 (TXB2), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and platelet cyclic 3'5'-adenosine monophosphate concentrations. Adverse effects on biochemical and rheological properties were not found. In conclusion, felodipine-ER is an effective and metabolically safe antihypertensive drug. It reduces platelet aggregability and intracellular free calcium concentration without altering the production of TXB2 and 6-keto-PGF1 alpha.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Transesophageal color Doppler flow imaging in the evaluation of prosthetic cardiac valves.

To determine the value of transesophageal echocardiography in the assessment of prosthetic cardiac valves, 11 patients with clinically suspected cardiac prosthetic valve dysfunction were studied by transesophageal two-dimensional imaging, as well as by color Doppler flow mapping. Among these 11 patients, there were 10 with biological tissue valves and 3 with metallic valves (1 Bjork-Shiley, 2 St. Jude). Nine patients had replacement of mitral valves alone. The remaining two had received both mitral and aortic prostheses. The degree of mitral regurgitation was graded by transesophageal color Doppler according to the area of the regurgitant jet visualized. The degree of aortic regurgitation was graded by the jet height/left ventricular outflow height ratio method. All transesophageal studies were performed without complication and all were well tolerated. The pathological morphology of the cardiac prosthesis was clearly visualized by transesophageal two-dimensional imaging and subsequently proven at surgery. Of those tested, one patient was found to have a torn leaflet, one had a dislodged leaflet, one patient had paravalvular leakage, four had cusp vegetations, and five patients had prosthetic degeneration for other reasons. Mitral regurgitation was graded as absent in one patient, mild in two patients, moderate in two patients, and severe in six patients. Aortic regurgitation was graded as severe in both patients with aortic prostheses. We conclude that in patients with clinically suspected cardiac prosthetic dysfunction, transesophageal two-dimensional imaging combined with color Doppler can provide reliable information that corresponds to surgical findings.

Adult↗
PubMed1992

Plasma triglycerides: a cardiovascular risk factor?

In a span of 3 decades, investigation as to whether elevated plasma triglyceride (TG) is associated with increased risk of coronary artery disease (CAD) produced results that have largely been inconsistent. Therefore, these investigations have been relegated to the background when compared to the significance give to cholesterol in the 80's. The first study to report an association between TG and myocardial infarction was in 1959. Since then, many other studies have been done starting from case control studies to prospective studies and then progressing to interventional studies. Many have found TG significant on a univariate but not on a multivariate analysis. Attempts have been made to analyse TG in diabetics, especially those with a normal cholesterol, in ischemic cerebrovascular disease (ICD), and in other disease states where atherosclerosis is involved in their pathogenesis. Of particular interest is that our studies in Taiwan have consistently showed that TG may indeed be an independent risk factor. Our subjects with ICD, CAD, and in different stages of hypertension, all had significant association with elevated TG. Statistical consider, i. e. discrepancy between univariate and a multivariate analysis, large variability of plasma TG distribution, as well as genetic susceptibility of certain individuals are also factors to be considered. No study to date has specifically been designed to evaluate TG lowering effects on primary prevention of CAD. Despite differences of opinion among the various authorities on this subject, I feel that the TG-CAD association should not be ignored and further intervention studies should be done.

Adult↗
PubMed1992

Internal mammary artery to pulmonary artery fistula associated with sick sinus syndrome: report of a case.

A 77-year-old woman presented with general weakness, dizziness and slow, irregular heart beats. An electrophysiologic study revealed a markedly prolonged sinus node recovery time of up to 5,900 msec, accompanied with dizziness. A permanent pacemaker with an AAIR mode was implanted. An abnormal shadow in the right lower lung field was found on chest x-ray. Selective arteriography revealed a right internal mammary to right pulmonary artery fistula. No significant hemodynamic abnormalities were found. This anomaly is extremely rare. Our patient is the oldest among 20 cases reported in the literature, and is the first one associated with sick sinus syndrome. Most reported cases have involved surgical ligation and excision, due to the risk of rupture of the malformation, endarteritis and congestive heart failure. Our patient refused surgical intervention and has done well during the past year.

Aged↗
PubMed1992

Effects of the calcium antagonist isradipine on 24-hour ambulatory blood pressure, platelet aggregation, and neutrophil oxygen free radicals in hypertension.

The effects of isradipine on ambulatory blood pressure, platelet aggregation, and oxygen free radicals were assessed in 30 patients with hypertension in a non-comparative 16-week study. After 4 weeks of placebo run-in, patients received isradipine at 2.5 mg twice daily for 12 weeks. The average supine systolic/diastolic blood pressure (155 +/- 17/101 +/- 11 mm Hg) was significantly reduced at the end of treatment (144 +/- 13/95 +/- 9 mm Hg; p less than 0.01). The heart rate was not significantly altered. Isradipine had no adverse effects on red or white blood cells or on plasma viscosity. The thromboxane B2 level and epinephrine-induced platelet aggregation were significantly (p less than 0.05) reduced. High-density lipoprotein cholesterol was significantly (p less than 0.01) increased after vs. before treatment; total cholesterol was significantly (p less than 0.05) increased at midstudy, but this was not significant at the end of the study. Other biochemical parameters were unchanged. Studies of neutrophil oxygen free radicals by serum opsonized zymosan and phorbol myristate acetate were not affected by isradipine. In conclusion, isradipine is an effective antihypertensive agent that also has beneficial effects on platelet aggregation and lipids while having no effects on neutrophil oxygen free radicals or most of the biochemical variables tested, making it an ideal agent for hypertension.

Aged↗
PubMed1991

The role of aggregation of platelets in pregnancy-induced hypertension: a comprehensive and longitudinal study.

Plasma 6-keto-prostaglandin F 1 alpha and thromboxane B2, the metabolites of prostacyclin and thromboxane A2 respectively, were measured in 12 women with pregnancy-induced hypertension, 12 age-matched normotensive pregnant women and 8 non-pregnant women as controls. Pregnancy was divided into 3 stages, namely: 22-27, 28-32 and 33-39 weeks. The concentrations of thromboxane B2 in the plasma of women with pregnancy-induced hypertension was 1.4-1.7 times greater than normotensive pregnant subjects at the same gestational stage, and 2 times higher than controls. Plasma levels of 6-keto-prostaglandin F 1 alpha in normotensive pregnant women was 1.8 times greater than in those with pregnancy-induced hypertension at 28-32 and 33-39 weeks, and was significantly higher than control. The ratio of thromboxane B2 to 6-keto-prostaglandin F 1 alpha was markedly increased in the group of patients with pregnancy-induced hypertension at 28-32 and 33-39 weeks gestation. The ratio of the two metabolites in normotensive patients at each stage of gestation was similar to the control group. The ratio of circulating aggregated platelets in subjects with pregnancy-induced hypertension was significantly lower than in normotensive pregnant subjects at 33-39 weeks, implying increased turnover of platelets in pregnancy-induced hypertension. There was no significant difference in count of platelets, adenosine diphosphate threshold concentration and variables of platelet aggregation induced by adenosine diphosphate among the 3 groups.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Relationship of platelet specific proteins and other factors to atherosclerosis in various stages of hypertension.

There is considerable evidence from previous studies that platelets play an important role in the development and progression of atherosclerosis in hypertension, more so in relation to the stage of hypertension. Seventy one hypertensive patients (WHO stage I: 39, stage II: 23, stage III: 9) aged 19-84 (mean age: 56, 59 and 62 respectively for each stage) and 37 normal controls (aged 22-72 with a mean age of 52) were involved in this study. Hematocrit, beta-thromboglobulin (beta-TG), platelet factor 4 (PF4), beta-TG/PF4 ratio, total cholesterol (TC), low density lipoprotein-C, and triglycerides were higher in the hypertensive group while platelet count, circulating platelet aggregates, and high density lipoprotein-C were higher in the normotensive group. Among the hypertensives, stage III patients showed the highest beta-TG, PF4, beta-TG/PF4 ratio, triglycerides, and stage I with the least elevation. There were no significant differences noted in the ADP or epinephrine-induced platelet aggregation in both the normal and hypertensive patients. Other parameters such as heart rate, serum sodium, potassium, renal and liver function tests, plasma renin activity, aldosterone, fibrinogen thromboxane B2 and 6-Keto-PGF1 alpha, showed no significant differences in both groups. This study clearly showed that beta-TG/PF4 ratio and triglycerides are closely related to the stage of hypertension and are good indicators of in vivo platelet activation in hypertensives which may account for the acceleration of hypertensive vascular complications secondary to atherogenesis.

Adult↗
PubMed1991

The role of endothelium in vascular response of diabetic rats.

The responses of aortas to various vasoactive agents were compared in streptozotocin-induced diabetic male rats and age-matched normal controls. There was a shift of the dose-response curve of norepinephrine (NE) to the right from streptozotocin-induced diabetic rats of 8 weeks duration as compared that of to normal rats. The median effective concentration (EC50) of NE in diabetic aortas to NE was significantly increased from 10(-7.5) M to 10(-7.2) M, while the maximum response of diabetic aortas to NE was not different from that of normal controls. In addition, the EC50 and maximum contractile response to KCl were also not different between the two groups. Meanwhile, the contractions induced by angiotensins I and II, were also significantly attenuated in diabetic aortas. The endothelium-dependent relaxation produced by carbachol in aortic rings which is precontracted with NE was significantly lower in diabetic preparations than that in age-matched control animals. The EC50 of carbachol in diabetic and normal aortas to carbachol were 2.8 x 10(-6) M vs 1.2 x 10(-6) M respectively. These results suggest that deterioration of endothelium might exist in diabetic rats.

Angiotensins↗
PubMed1991

[Metabolic effects of chlorothiazide and propranolol on essential hypertension--a double-blind, cross-over design clinical trial].

Several studies have shown that antihypertensive drugs therapy could reduce morbidity and mortality of hypertension related complication such as stroke, congestive heart failure and renal failure, but there was no significant reduction of coronary heart disease. The benefit of the treatment on morbidity and mortality may be counterbalanced by adversed metabolic effects of long-term therapy. The purpose of this study is to evaluate the blood pressure-lowering and adverse metabolic effects of chlorothiazide and propranolol monotherapy. A double-blind, cross-over design clinical trial was performed for 42 cases (22 males and 20 females) with the mean age of 52 (from 30 to 59 years old). After 2 weeks run-in period, the patients were assigned to group A and B with age and sex stratification. Chlorothiazide and propranolol were given for 12 weeks in alternative with 2 weeks placebo washout period. Our studies have shown that, chlorothiazide and propranolol could reduce both systolic and diastolic blood pressure significantly. But they also associated with adverse metabolic effects. Serum uric acid and triglyceride increased and decreased the concentration of high density lipoprotein cholesterol (HDL-C). Those changes could counterbalance the benefit of blood pressure-lowering effect of antihypertension. Carefully monitoring the adverse metabolic effects closely is necessary in therapy with these drugs.

Adult↗