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Biomedical subjects

L S Liu

Publications and source records attributed to L S Liu.

At least 55 records · Page 3Linked to original sources
PubMed1991

In vitro non-thrombogenicity of a thrombin-substrate-immobilized polymer surface by the inhibition of thrombin activity.

Derivatives of thrombin substrate were synthesized and immobilized on a poly(acrylic acid)-grafted polyurethane film. The carboxyl terminal of the thrombin substrate peptide should be blocked for a higher inhibitory effect of the thrombin activity. Immobilization of the thrombin substrate peptide enhanced adsorption and inactivation of thrombin on the polymer film to prolong the time for fibrin network formation, and suppressed adhesion and deformation of platelets on the film. Consequently, in vitro thrombus formation on the polymer film was strongly suppressed.

Amino Acid Sequence↗
PubMed1991

DNA synthesis inhibition of nitroxide radicals on leukemia cells.

4-isothiocyanate-2,2,6,6-tetramethyl-piperidine-1-oxyl has the strongest effects on the DNA synthesis and viability of isolated leukemia 7712 cells. This compound is a very potent inhibitor of DNA synthesis with 50% inhibition of cell DNA synthesis occurring at 2.2 micrograms/ml, while the LD50 for white mice is 277 mg/kg. During the concentration of 50 micrograms/ml, the inhibition of DNA synthesis is 99.7%, which is unable to damage the DNA replicate template. The inhibition of this compound, a combination of nitroxide and isothiocyanate, appears to be stronger than that of the sum of the two separate actions. Much more moderate effects are seen for all the other nitroxide radicals. After reducing nitroxide to hydroxylamine, there is no inhibition for DNA synthesis. The free radical mechanism of carcinogenesis and antitumor action has been discussed.

Animals↗
PubMed1990

Urinary cations and blood pressure in the Chinese population.

Three collaborative studies on the relationship between blood pressure (BP) and urinary electrolytes confirmed a positive intrapopulation relationship between sodium (Na) intake and BP, especially in the northern districts of China. In the present article, data of overnight urinary electrolytes and BP of 3,251 subjects from 16 districts of China were pooled and analyzed. A consistent significantly positive correlation was shown between BP and UNa/UK ratio. Both men and women with a UCa less than 10 mmol/day showed a significant correlation of BP with UNa/UK. After age, body mass index adjusted, the correlation between BP and UNa or UNa/UCr showed consistently in males. BP correlated negatively with UCa only in men, whereas women in the age 50-59 group were found most sensitive to UNa/UK and a negative correlation of diastolic BP with UK was only found in women.

Adult↗
PubMed1990

Clinical studies in 500 patients with aortoarteritis.

Five hundred patients with aortoarteritis were studied in this series. The long-term administration of small dosage of corticosteroid is effective in treating this disease in its active stage. The patients with renal vascular hypertension should be treated by percutaneous transluminal renal angioplasty or by surgery if indicated. About one third of the pulsations of the involved arteries were improved. The incidence of complications was 17% and the mortality rate was 11% in this series. Cerebral thrombosis was found as a common complication and hemorrhage as a common cause of death. Three patients died of heart failure without aortic regurgitation. Five-year and ten-year survival rates were 93.1% and 91.1% respectively.

Adolescent↗
PubMed1990

Comparison of erythrocyte membrane Ca2(+)-Mg2(+)-ATPase activity in children with and without family history of essential hypertension.

The causes of elevated intra-erythrocyte calcium in the offspring of essential hypertensive patients are unknown. Fourteen children with and without a family history of essential hypertension were chosen to compare erythrocyte membrane Ca2(+)-Mg2(+)-ATPase activity (Rbc-M Ca2(+)-Mg2(+)-ATPase activity) measured by biochemical methods. We found that Rbc-M Ca2(+)-Mg2(+)-ATPase activity was lower in children with family history of hypertension compared with children with no family history (2.16 +/- 1.10 vs 3.36 +/- 1.19 microM Pi/mg protein/hour P less than 0.01). These results suggest that the reduced Rbc-M Ca2(+)-Mg2(+)-ATPase activity may be one of the mechanisms causing the high erythrocyte calcium levels in the offspring of essential hypertensive patients.

Adolescent↗
PubMed1990

Renovascular hypertension in China--report of 200 cases.

Renal arteritis and fibromuscular dysplasia are two common causes of renovascular hypertension in China. The diagnostic approach now is arteriography or digital subtraction arteriography first, followed by renal vein renin assays to evaluate the functional significance. Surgical treatment is preferred if clinical status of the patients permits.

Adolescent↗
PubMed1990

The value of the captopril test and the effect of captopril on renal function.

We have investigated the use of captopril as a screening test for renovascular hypertension and compared the effects of captopril on renal function in patients with renovascular hypertension and those without renovascular hypertension. The captopril test and kidney gamma scintigraphy were carried out in 50 hypertensive patients, 13 with renovascular hypertension and 37 without. Blood samples were drawn for the determination of plasma renin activity and kidney gamma scintigraphy was done before and 60 minutes after 50 mg oral captopril administration. Results suggesting the diagnosis of renovascular hypertension are the following: a basal and stimulated plasma renin activity of 4 ng ml/hr or more and an absolute increase in plasma renin activity of 3 ng/ml/hr or more if basal plasma renin activity was less than 4 ng/ml/hr. Data from kidney gamma scintigraphy showed that captopril causes a decrease in clearance rate at 20 minutes in patients with renovascular hypertension but not in patients without renovascular hypertension. We conclude that the captopril test can be used to screen for renovascular hypertension, but catopril may impair the renovascular hypertensive patient's renal function.

Adult↗
PubMed1990

Epidemiology of hypertension and cardiovascular disease--China experience.

Epidemiological studies show higher BP level, lipid level and higher prevalence of coronary atherosclerosis and stenosis, in north than in south China. Urban populations have higher prevalence of HT than rural, high altitude dwellers usually have lower prevalence. Genetic differences start to affect BP from early childhood, children from higher BP parents are found more salt sensitive. Higher Na and Na/K, lower protein and Ca in the north, are important dietary factors in explaining north-south difference. Low prevalence of high altitude dwellers is found to be related with low salt intake, less stress perhaps also hypoxia. CVD Community control program has started since 1969, from 1969-1989, eleven such programs have been established in Beijing covering a total population of 750,000. Encouraging results in reduction of CVD mortality and morbidity rates have been obtained. Primary prevention by restriction of Na and supplementation of calcium has been tried and found to be eligible preventive measures.

Adult↗
PubMed1990

Aortoarteritis: a report of 480 cases.

We report 480 patients with aorto-arteritis studied in our group. Among 320 patients, who were diagnosed by aortography the female to male ratio was 2.8:1, and the age of onset ranged from 5-45 years. The patients were followed for 1-27 years (average 6.8 years). Two hundred and eighty-six (59.6%) patients with renovascular hypertension were found in the group. All patients were treated with medical or surgical procedures. One hundred and thirty patients with renovascular hypertension were operated upon by revascularisation or uninephrectomy and 11 patients with renal artery stenosis were subjected to percutaneous transluminal renal angioplasty. There were 55 deaths (11.5%) in the group, cerebral haemorrhage being the major cause of death. Five year and ten year survival rates were 93.1% and 91.1% respectively.

Adolescent↗
PubMed1989

Atrial natriuretic peptide lowers pulmonary arterial pressure in patients with high altitude disease.

The authors' previous studies have demonstrated that IV administration of atrial natriuretic peptide (ANP) produces a dose dependent decrease in pulmonary arterial pressure in rats adapted to chronic hypoxia. To examine the effects of ANP on chronic hypoxic pulmonary hypertension in man, alpha-human ANP (200 micrograms) was infused (20 micrograms/min X 10 min) into the right atrium via a Swan-Ganz catheter in four patients with pulmonary hypertension of high altitude. Following the infusion, pulmonary arterial pressure fell gradually and remained depressed for 1 hour. Peak reductions in pulmonary arterial systolic pressure (PASP) and mean pulmonary arterial pressure (MPAP) were 23% and 30%, respectively. Systemic arterial pressure, cardiac output and cardiac index also tended to decrease, but these changes did not reach statistical significance. The data suggest that ANP is useful in the treatment of chronic hypoxic pulmonary hypertension in man.

Aldosterone↗
PubMed1989

Calcium antagonists in prevention of hypertension and stroke in stroke-prone spontaneously hypertensive rats.

To investigate the effect of Calcium antagonists (Ca-An) with different tissue specificity in the development of hypertension and stroke in salt-loading SHRSP, three experiments were conducted. In experiment I (1), 50 8-week-old male SHRSP were divided into three groups and given nifedipine (NF, 32 mg/kg/day), menidipine (MN 32 mg/kg/day) and placebo (control group) respectively. In the control group 83.3% (15/18) died of stroke and 17 showed renal vascular sclerosis. Their average lifespan was 84 days. NF and MN significantly reduced systolic blood pressure (SBP), and no stroke of renal vascular sclerosis developed. In experiment I (2), 54 7-week-old male SHRSP were divided into three groups (18 in each group). They were treated with nimodipine (NM) 20 mg/kg/day, 2 mg/kg/day and placebo respectively. NM (20 mg/kg/day) markedly lowered SBP and postponed the onset of stroke. Only 11% died in 17 weeks. NM (2 mg/kg/day did not lower SBP but postpond the onset of stroke. In experiment II (1), 29 10-week-old female SHRSP were divided into three groups: Group A was given NF 32 mg/kg/day, group B was parathyroidectomized (PTX) and group C served as control. PTX group did not lower SBP but could postpone the onset of stroke. In experiment II (2), 33 male SHRSP were divided into three groups and ticated as described above in experiment II (1) (11 in each group). Seven weeks after the experiment, the brain blood flow of NF group was significantly greater (67.5%) than that of the control and PTX groups. In experiment III, 27 7-week-old male SHRSP were divided into three groups as described above in experiment I (2).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Calcitonin gene-related peptide in the pathogenesis and treatment of hypertension.

The present study demonstrated that the plasma calcitonin gene-related peptide (CGRP) concentration was lower but the CGRP content of abdominal aorta was higher in spontaneously hypertensive rats (SHR) than in normotensive rats (WKY), using specific CGRP radioimmunoassay (P less than 0.01). In eighteen patients with essential hypertension, the concentration of plasma CGRP was also much lower than that of normal subjects, suggesting that a decreased release of arterial CGRP might be a part of the pathogenesis of essential hypertension. In SHR, a significant decrease in blood pressure was found following intravenous injection of 2.5 micrograms/kg of CGRP; similarly, in seven patients with essential hypertension intravenous injection of CGRP (50 micrograms) could induce a significant hypotensive effect. These data suggest that CGRP is a new potential drug for the treatment of essential hypertension.

Adult↗
PubMed1989

[Comparison of erythrocyte membrane Ca2(+)-Mg2(+)-ATPase activity in children with and without a family history of essential hypertension].

15 children with and without family history of essential hypertension respectively were chosen to compare erythrocyte membrane Ca2(+)-Mg2(+)-ATPase activity measured with biochemical method. Results were as follows: erythrocyte membrane Ca2(+)-Mg2(+)-ATPase activity was lower in children with family history of essential hypertension (2.16 +/- 1.10 vs 3.36 +/- 1.19 mumol Pi.mg protein-1/hour, P less than 0.01). This may be the cause of increase of intraerythrocyte calcium in offspring of hypertensive patients.

Adolescent↗
PubMed1989

Hypertension studies in China.

Hypertension accounts for 25-50% of all deaths in China each year and its prevalence has been found to be increasing for the past 20 years. Blood pressure surveys showed that urban populations had a higher prevalence as well as an earlier and more rapid rise in prevalence rates than rural populations. Northern and northeastern districts, and the more prosperous eastern part of China also had higher prevalence rates. Community control of hypertension has been organized since 1969, and an obvious leftward shift of systolic and diastolic blood pressure was noticed after 10 years of community control. Stroke is much more common than acute myocardial infarction, its annual incidence rate (130-160 per 100,000) being five fold higher (1). Based upon the above situations, an outline is given of the studies which have been carried out in China in the past 5 years.

Adolescent↗
PubMed1989

[Effects of complex of 3,6-di-(dimethylamino)-dibenzopyriodonium with praseodymium dicitrate on the syntheses of DNA, RNA, protein, nucleoprotein and ATP of leukemia L 7712 cells in mice].

The incorporations of [3H] thymidine, [3H]uridine and [3H]leucine into DNA, RNA and protein synthesis in leukemia 7712 cells were inhibited by the complex of 3,6-di-(dimethylamino)-dibenzopyriodonium with praseodymium (Pr, rare earth element) dicitrite 34 micrograms/ml for 3-24 h. The degree of inhibition increased in proportion to the incubation time. After being treated with [C17H20N2I]3[Pr(C6H5O7)2] 34 micrograms/ml for 3, 6, 12 and 24 h, the incorporation of [32P]Na2HPO4 into the nucleoprotein of leukemia 7712 cells was inhibited by 49, 57, 65 and 85%, while those into ATP were inhibited by 43, 59, 65 and 83%, respectively. The ID50 of [C17H20N2I]3[Pr(C6H5O7)2] on DNA synthesis in leukemia 7712 cells at 24 h was 22 micrograms/ml. After the complex was removed from the medium entirely, the rate of DNA synthesis decreased with time over 3-12 h. This result indicated that the inhibition mechanism was likely due to damage to the DNA template.

Adenosine Triphosphate↗