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Biomedical subjects

F J Lu

Publications and source records attributed to F J Lu.

At least 55 records · Page 3Linked to original sources
PubMed1997

Superoxide anion scavenge effect of Quercus glauca Thunb. in whole blood of patients with ankylosing spondylitis.

Nine phenolic compounds, catechin (1), epicatechin (2), gallocatechin (3), epigallocatechin (4), procyanidin B-4 (5), catechin-3-O-rhamnoside (6), rutin (7), querglanin (8) and isoquerglanin (9) were isolated from oak leaves (Quercus glauca Thunb. Fagaceae), and the latter two (8, 9) were identified as new compounds. Several Quercus species have been used in folk medicine as an astringent for hemorrhoids and for treatment of inflammation, jaundice, and tumor. In this study, these compounds were tested for scavenging effects of the superoxide anion in the whole blood of patients with ankylosing spondylitis by means of an ultra-sensitive chemoluminescence (CL) analyzer and lucigenin amplification. The results showed that at a concentration of 2.3 x 10(-5) M, isoquerglanin (9) displayed the strongest inhibition activity (73.55%), followed by querglanin (8) (68.81%) and then gallocatechin (3) and epigallocatechin (4) (66.97 and 60.17% inhibition, respectively). In addition, the blood chemoluminescence (CL) level of patients with ankylosing spondylitis was inhibited by superoxide dismutase (SOD) but not by catalase, suggesting that superoxide anion is the major component of reactive oxygen species (ROS) involved in this assay system.

Acridines↗
PubMed1997

Biochemical events associated with ligation of the common bile duct in Wistar rats.

Oxygen free radicals have been implicated as mediators of tissue injury in a variety of diseases. We investigated the role of oxidative injury and oxygen free radical scavengers in liver cell injury associated with obstructive jaundice in Wistar rats. Bile duct ligation for 4 or 7 days led to a decrease in both vitamin E and A in the plasma and liver of male Wistar rats, indicating the malabsorption of lipid-soluble vitamins. Serum bilirubin, alkaline phosphatase and gamma-glutamyl transpeptidase activities were increased in the bile-duct-ligated rats. Furthermore, marked increases in lipid peroxide and oxidized glutathione levels indicated cholestatic liver injury. The antioxidant defense system was impaired, as shown by decreases in reduced glutathione and in the activities of glutathione peroxidase (GSH-Px) and superoxide dismutase. Moreover, these high lipid peroxide levels and low levels of antioxidants correlated with the severity of jaundice. After releasing the bile duct ligation, levels of bilirubin, lipid peroxide and oxidized glutathione declined, while the levels of vitamin E and A, reduced glutathione, and the activities of GSH-Px increased, indicating an improvement in liver function. These findings suggest that lipid peroxidation is associated with the pathogenesis of liver damage in animals with bile duct ligation. Meanwhile, free oxygen radical scavengers are reduced in the bile-duct-ligated rats, thereby increasing the susceptibility of the liver to injury by oxygen-derived free radicals.

Animals↗
PubMed1996

A simple, sensitive, non-stimulated photon counting system for detection of superoxide anion in whole blood.

A simple, sensitive, non-stimulated assay was developed to measure the superoxide anion concentration in whole blood, using an ultra-sensitive chemiluminescence (CL) analyzer and lucigenin amplification. The assay system can be performed without leukocyte isolation or stimulant administration. The blood CL levels of healthy males (362.8 +/- 337.7 counts /10 sec) were not different from those of females (335 +/- 308.7 counts/10 sec) (p=0.64), whereas the CL levels in whole blood in patients with acute pancreatitis (2522 +/- 2014 counts/10 sec) were significantly higher than those of healthy controls (p<0.001). This assay system may be valuable in the future for quantitative measurement of reactive oxygen species in various disorders.

Acridines↗
PubMed1996

Effects of humic acid on the viability and coagulant properties of human umbilical vein endothelial cells.

We have previously shown that humic acid (well-water humic acid, HA, and synthetic humic acid, SHA) enhances cell surface expression of tissue factor (TF). Here we report that incubation of human umbilical vein endothelial cells (HUVEC) for 2 hr with HA or SHA cause a rapid rise in TF mRNA levels, as shown by Northern blot analysis. To understand the cytotoxic and fibrinolytic effects of HA and SHA on cultured HUVEC, the cells treated with varying concentrations of HA and SHA for various periods of time. Both HA and SHA (10-200 micrograms/ml) inhibited the viability of subconfluent HUVEC, cultured in the presence or absence of 20% FBS (Fetal Bovine serum) in the culture medium, in a dose-dependent manner. Both HA and SHA induced surface changes in the HUVEC as revealed by scanning electron micrography (SEM). However, protocatechuic acid, the monomer of SHA, did not significantly inhibit cell growth, and showed a cytotoxic effect only at 200 micrograms/ml. Furthermore both HA and SHA stimulated HUVEC to produce plasminogen activator inhibitor (PAI-1) and tissue plasminogen activator (t-PA) in a dose and time dependent fashion; the amount of PAI-1 produced was found to exceed that of t-PA. The monomer of SHA did not have this stimulatory effect. These results distinctly suggest that in addition to the inhibition of viability HA is involved in TF induction and PAI-1 synthesis in HUVEC and these may be some of the plausible mechanisms underlying the thrombotic disorders in Blackfoot disease.

Arterial Occlusive Diseases↗
PubMed1996

A simple chemiluminescence assay for detecting oxidative stress in ischemic limb injury.

This study was designed to evaluate a simple, sensitive, nonstimulated chemiluminescence assay to measure the oxidative stress production in the whole blood of rabbits after an ischemic insult. By using an ultra-sensitive chemiluminescence (CL) analyzer and lucigenin amplification, the assay system can be performed without leukocyte isolation and stimulant administration. The blood CL levels of healthy rabbits were 122 +/- 18 counts/10 s. After 8 h of ischemia, the CL levels of whole blood immediately after reperfusion, 1 h, 2 h, 24 h, 48 h, 7 days, and 14 days of reperfusion were 409 +/- 78 counts/10 s, 283 +/- 55 counts/10 s, 256 +/- 43 counts/10 s, 228 +/- 33 counts/10 s, 185 +/- 32 counts/10 s, 160 +/- 16 counts/10 s, and 119 +/- 15 counts/10 s. The differences were statistically significant between the control and samples obtained up to 24 h after reperfusion. The corresponding creatine phosphate kinase (CPK) levels of the rabbits in this study were 938 +/- 43 U/l for the control blood sample and 5921 +/- 498 U/l, 6948 +/- 427 U/l, 6860 +/- 1115 U/l, 5763 +/- 516 U/l, 1545 +/- 291 U/l, 478 +/- 60 U/l, and 458 +/- 48 U/l for the experimental blood samples. The CPK levels of the blood samples before 24 h and after 7 days of reperfusion were significantly different to that of the control blood sample. The changes in the CL and CPK levels were quite similar before 48 h reperfusion. This assay has proved to be valuable in the quantitative measurement of ischemic insults of skeletal muscles.

Acridines↗
PubMed1996

Protective and therapeutic effects of huanglian-jie-du-tang on hepatotoxin-induced liver injuries.

The hepatoprotective effect of Huanglian-Jie-Du-Tang (HLJDT), a Chinese medicinal prescription, was investigated in three kinds of experimental models. The animals were treated with HLJDT (300 mg/kg, p.o.) thrice at 2, 4 and 10 hours after administration with carbon tetrachloride (32 microliters/kg, i.p.), acetaminophen (600 mg/kg, i.p.) and beta-D-galactosamine (188 mg/kg, i.p.). Significant hepatoprotective effects on carbon tetrachloride and acetaminophen induced liver injuries were noted, but no significant effect on beta-D-galactosamine induced liver injury was observed. These hepatoprotective effects were evidenced by comparing the serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) levels in HLJDT treated and untreated groups. Serum enzyme activities in the carbon tetrachloride and acetaminophen experiments were significantly lower in the treated groups while the herbal prescription has no effect on the beta-D-galactosamine experiment. These results demonstrated that Huanglian-Jie-Du-Tang has a hepatoprotective effect against experimental liver injuries induced by specific hepatotoxins, and therefore may be useful in treating some, but not all, liver injuries.

Animals↗
PubMed1995

Prevalence of goiters in children residing in Tung-Lo Township, Taiwan.

This study investigated school children in the Tung-Lo Township in central Taiwan to determine the prevalence of goiters compared to other areas of Taiwan and to elucidate the possible etiology. All children attending elementary schools in Tung-Lo were examined for thyroid enlargement by neck palpation, as recommended by the World Health Organization. Thyroid antibodies and thyroid hormones were determined in children with goiters, and in normal age- and sex-matched controls. Additionally, analysis of drinking water for humic substances was done by fluorospectrophotometry. In total, 1,823 school children were examined (965 boys and 858 girls). Of these, 174 (9.5%) were found to have a goiter of grade I or above. The prevalence was higher than our recent surveys in other areas of Taiwan (2.6%-8.8%). Goiter prevalence in school children residing in hill regions (12.9%), mainly dependent on underground water for drinking, was higher than that of school children residing in plain regions (8.2%), who depend on tap water for drinking. The quality of drinking water bore a close relationship to the prevalence of goiter. From the ratio of T3/T4 in this study, and a study of urinary iodine excretion done by others, it is concluded that goiters in Tung-Lo are not related to iodine deficiency. There was no statistically significant correlation between the relative fluorescence intensity of humic substances and the prevalence of goiter. The results of this study suggest that the higher prevalence of goiter in children living in Tung-Lo, an oil-bearing area, may be related to the quality of drinking water.

Child↗
PubMed1994

Plasma protein C activity is enhanced by arsenic but inhibited by fluorescent humic acid associated with blackfoot disease.

Blackfoot disease is a peripheral vascular disease causally related to the fluorescent humic acid found in the drinking water of endemic areas in Taiwan. We compared the effects of humic acid (HA) purified from the well water of Blackfoot disease endemic areas with the effects of commercial humic acid (Aldrich) as well as trivalent arsenic (As2O3) on protein C activity, which plays an important role in regulation of blood coagulation and fibrinolysis. Humic acid, either purified from drinking water or obtained commercially, dose-dependently inhibited both activated protein C activity and the activation of protein C induced by Protac, a snake venom-derived protein C activator. In contrast to humic acid, arsenic oxide dose-dependently enhanced both activated protein C activity and the Protac-stimulated activation of protein C. In the presence of humic acid the enhancement effect of arsenic oxide was completely abolished, resulting in concentration-dependent inhibition of protein C activity. Therefore, the results of this study indicate that humic acid is a potent protein C inhibitor even in the presence of arsenic, which enhances the protein C activity. Since protein C is a potent anticoagulant and profibrinolytic agent, acquired defects of protein C induced by humic acid might cause a thrombophilic or hypercoagulable state. Whether this is one of the possible mechanisms of humic acid-induced thrombotic disorders in Blackfoot disease needs to be further characterized.

Arsenic↗
PubMed1994

Effect of humic acids on thyroidal function.

Humic substances (HS) have been implicated as environmental goitrogens. Increased prevalence of goiter has been recently noticed in the blackfoot disease endemic area on the southwest coast of Taiwan, where well water is rich in HS. This study investigated the in vivo effects of humic acids (HA) on the thyroid gland of rats and mice. Groups of mice and rats were fed regular or moderately iodine deficient (approximately 167 vs 700 micrograms l- per kg) chow and distilled water or HA water (1mg/ml) for 3 or 4 months. Serum T4, T3, reverse T3, and/or TSH were measured by radioimmunoassay. Thyroidal 125I uptake was measured in mice at 2 h after injection of 1 microCi125I ip. Treatment of the rat with HA was associated with a significantly (p < 0.05) reduced serum T4 without a change in other parameters of study. Treatment with low iodine diet was associated with a clear increase in serum T3 and a decrease in serum rT3. Rats treated with both HA and low iodine diet showed a significantly reduced serum T4, increased serum T3 and decreased serum rT3. In mice, treatment with low iodine diet significantly increased thyroidal 125I uptake and additional treatment with HA significantly enhanced the effect of low iodine diet. Treatment with HA did not influence thyroid weight of rats or mice given normal or iodine deficient diets. We conclude that HA per se do not induce goiter, but they may enhance the goitrogenic effect of low iodine.

Animal Feed↗
PubMed1994

Eugenol triggers different pathobiological effects on human oral mucosal fibroblasts.

Pathobiological effects of eugenol (4-allyl-2-methoxyphenol), a major constituent of betel quid (BQ), were studied on oral mucosal fibroblasts. At a concentration higher than 3 mmol/L, eugenol was cytotoxic to oral mucosal fibroblasts in a concentration- and time-dependent manner. Cell death was associated with intracellular depletion of glutathione (GSH). Most of the GSH was depleted prior to the onset of cell death. At concentrations of 3 mmol/L and 4 mmol/L, eugenol depleted about 45% and 77% of GSH after one-hour incubation. In addition, eugenol decreased cellular ATP level in a concentration- and time-dependent manner. Eugenol also inhibited lipid peroxidation. Inhibition of lipid peroxidation was partially explained by its dose-dependent inhibition of xanthine oxidase activity. The IC50 of eugenol on xanthine oxidase activity was about 0.3 mmol/L. No DNA strand break activity for eugenol was found at concentrations between 0.5 and 3 mmol/L. Taken together, frequent exposure of oral mucosa to a high concentration of eugenol during the chewing of BQ might be involved in the pathogenesis of oral submucous fibrosis and oral cancer via its cytotoxicity. In contrast, eugenol at a concentration less than 1 mmol/L might protect cells from the genetic attack of reactive oxygen species via inhibition of xanthine oxidase activity and lipid peroxidation.

Adenosine Triphosphate↗
PubMed1994

Xanthine oxidase inhibitors from the leaves of Alsophila spinulosa (Hook) Tryon.

Diploptene(1), beta-sitosterol(2), a mixture of 6'-O-(E-P-coumaroyl)-alpha-glucopyranose and 6'-O-(E-P-coumaroyl)-beta-glucopyranose(3), a mixture of 6'-O-(E-P-caffeoyl)-alpha-glucopyranose and 6'-O-(E-P-caffeoyl)-beta-glucopyranose(4), caffeic acid(5) and astragalin(6) were isolated from an ethanolic extract of the leaves of Alsophila spinulosa Hook Tryon (Cyatheaceae). The plant has been used in folk medicine for hepatitis, gout, rheumatism, and tumor and these compounds were tested for their inhibitory effect on xanthine oxidase. Caffeic acid was the most potent constituent (IC50 = 39.21 microM; Ki = 28.2 microM) and was an uncompetitive inhibitor of the enzyme with respect to the substrate xanthine.

Magnetic Resonance Spectroscopy↗
PubMed1994

Humic acid induces expression of tissue factor by cultured endothelial cells: regulation by cytosolic calcium and protein kinase C.

Blackfoot disease is a thrombotic peripheral vascular disease causally related to the fluorescent humic acid (HA) found in the drinking water of wells in endemic areas in Taiwan. In this study we examined the effect of HA on tissue factor (TF) expression by vascular endothelial cells. Incubation of cultured human umbilical vein endothelial cells (HUVEC) with HA isolated from endemic area drinking water or with a synthetic humic acid polymer (SHA), resulted in enhanced cell surface expression of TF activity by HUVEC. The intracellular calcium level ([Ca2+]i) was measured using a calcium-specific fluorescent probe, fura 2. Changes in [Ca2+]i level were followed and quantitatively analyzed by spectrofluorometric microscopy, after incubation of the fura 2-loaded HUVEC with HA or SHA in a medium containing 1.8 mM CaCl2. Both HA and SHA increased [Ca2+]i in the presence of extracellular calcium ions, but not in their absence, indicating that influx of extracellular Ca2+ occurred during incubation of HUVEC with HA or SHA. Verapamil, a potent calcium channel blocker, did not abolish the enhancement of [Ca2+]i induced by HA or SHA, indicating that specific calcium channels may not be involved in the HA/SHA-induced elevation of [Ca2+]i. The elevated [Ca2+]i level induced by HA or SHA returned to basal level following removal of HA or SHA and incubation of the washed cells in medium containing 1.8 mM CaCl2. All these changes occurred in the absence of significant cytotoxic effects.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1993

Stimulation of endothelin production in cultured human endothelial cells by fluorescent compounds associated with blackfoot disease.

The fluorescent compounds (FC) in humic substances isolated from the drinking water of endemic areas of blackfoot disease have been characterized as the causative factor of the disease. In this report we studied the effects of these fluorescent compounds on the synthesis and secretion of endothelin-1 by cultured human umbilical cord vein endothelial cells (HUVEC) in order to explore the possible pathological mechanism(s) of FC in the development of atherothrombotic vasculopathy in blackfoot disease. Incubation of confluent HUVEC with FC (100 micrograms/ml) enhanced endothelin mRNA expression. A sensitive ELISA method was developed to quantitate secreted endothelin antigen levels in conditioned medium. Incubation of confluent HUVEC cultures with different concentrations of FC (0-200 micrograms/ml) resulted in concentration-dependent enhanced production of endothelin. No significant changes in endothelin production were observed when subconfluent HUVEC cultures were incubated with FC. FC dose-dependently reduced the growth rate of subconfluent cultured HUVEC and exerted cytotoxic effects on the viability and integrity of confluent HUVEC monolayers. Since endothelin is one of the most potent vasoconstrictors affecting blood pressure and blood flow, and is mitogenic for smooth muscle cell proliferation, these results imply that the enhanced endothelin production and the reduced cell viability and growth rate induced by FC may contribute to the atherothrombotic vasculopathy observed in blackfoot disease.

Arterial Occlusive Diseases↗
PubMed1992

Humic acid: inhibitor of plasmin.

Synthetic humic acid, well water humic acid and commercial humic acid (Aldrich) all have the ability to inhibit human plasmin activity. At a concentration of 20 micrograms/ml, all three species will result in 93%, 70% and 40% of residual plasmin activity, respectively. The components of humic acid, such as protocatechuic acid, resorcinol, vanillic acid and ferulic acid do not have such inhibitory activities. The ability of humic acid to inhibit human plasmin has not been reported. It is, therefore, a new plasmin inhibitor.

Coumaric Acids↗