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Biomedical subjects

W G Li

Publications and source records attributed to W G Li.

At least 37 records · Page 2Linked to original sources
PubMed2000

Enhanced H(2)O(2)-induced cytotoxicity in "epithelioid" smooth muscle cells: implications for neointimal regression.

Vascular smooth muscle cells (SMCs) are phenotypically diverse. Although most medial SMCs can be classified as "fusiform," others are of the "epithelioid" phenotype. Proliferation and apoptosis of epithelioid SMCs may contribute importantly to neointimal formation and regression, respectively. Because reactive oxygen species (ROS) are increased in vascular injury and can induce apoptosis of SMCs, we compared the effects of ROS on epithelioid and fusiform SMCs. Epithelioid and fusiform SMC lines were clonally isolated from rat aortic media and studied under similar conditions and passage numbers. H(2)O(2) produced dose- and time-dependent cytotoxicity that was enhanced in epithelioid compared with fusiform cells. After 24-hour exposure to 50 micromol/L H(2)O(2), epithelioid cell numbers were reduced by 34+/-5% versus a 3+/-5% (P<0.05) reduction in fusiform cell numbers. Similar results were obtained whether H(2)O(2) was administered to growth-arrested or growing cells or when epithelioid and fusiform cells were exposed to extracellular O(2)(.-). To investigate whether apoptosis contributed to enhanced ROS-induced cytotoxicity in epithelioid SMCs, terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin nick-end labeling (TUNEL) staining was performed. The incidence of TUNEL positivity was 5-fold increased in epithelioid versus fusiform SMCs after treatment with 50 micromol/L H(2)O(2) (19+/-1% epithelioid versus 5+/-1% fusiform, P<0.05). Enhanced H(2)O(2)-induced apoptosis in epithelioid SMCs was confirmed by DNA laddering. Furthermore, when balloon-injured aortas were exposed to H(2)O(2) ex vivo, enhanced apoptosis was observed in neointimal compared with medial SMCs. These results suggest that epithelioid SMCs exhibit enhanced sensitivity to ROS-induced apoptosis, which may play an important role in neointimal regression.

Animals↗
PubMed1999

Overexpression of human catalase inhibits proliferation and promotes apoptosis in vascular smooth muscle cells.

The role of reactive oxygen species, such as superoxide anions (O(2). (-)) and hydrogen peroxide (H(2)O(2)), in modulating vascular smooth muscle cell proliferation and viability is controversial. To investigate the role of endogenously produced H(2)O(2), rat aortic smooth muscle cells were infected with adenoviral vectors containing cDNA for human catalase (AdCat) or a control gene, beta-galactosidase (AdLacZ). Infection with AdCat resulted in dose-dependent increases in intracellular catalase protein, which was predominantly localized to peroxisomes. After infection with 100 multiplicity of infection (MOI) of AdCat, cellular catalase activity was increased by 50- to 100-fold, and intracellular H(2)O(2) concentration was reduced, as compared with control. Infection with AdCat reduced [(3)H]thymidine uptake, an index of DNA synthesis, in cells maintained in medium supplemented with 2% serum (0.37+/-0.09 disintegrations per minute per cell [AdLacZ] versus 0.22+/-0.08 disintegrations per minute per cell [AdCat], P<0.05). Five days after infection with 100 MOI of AdCat, cell numbers were reduced as compared with noninfected or AdLacZ-infected cells (157 780+/-8413 [AdCat], P<0.05 versus 233 700+/-3032 [noninfected] or 222 410+/-5332 [AdLacZ]). Furthermore, the number of apoptotic cells was increased 5-fold after infection with 100 MOI of AdCat as compared with control. Infection with AdCat resulted in induction of cyclooxygenase (COX)-2, and treatment with a COX-2 inhibitor overcame the AdCat-induced reduction in cell numbers. These findings indicate that overexpression of catalase inhibited smooth muscle proliferation while increasing the rate of apoptosis, possibly through a COX-2-dependent mechanism. Our results suggest that endogenously produced H(2)O(2) importantly modulates survival and proliferation of vascular smooth muscle cells.

Animals↗
PubMed1999

Effect of recombinant human basic fibroblast growth factor on stomach ulcers in rats and mice.

AIM: To study the curative effects of recombinant human basic fibroblast growth factor (rh-bFGF) on gastric ulcer healing. METHODS: Pylorus ligated, water immersion stress-induced, reserpine-induced, and acetic acid-induced gastric ulcers in rats or mice were prepared. Morphometric analyses on ulcer were performed using microscope and true color image analysis system. The DNA and RNA contents were measured by diphenylamine method and orcinol method, respectively. RESULTS: In acetic acid-induced gastric ulcers in rats, rh-bFGF 2.5-40 kU.kg-1 i.g. accelerated the chronic ulcer healing with a bell-shaped dose-effect curve and the best dosage was 10 kU.kg-1. The regenerated gland epithelium width, density of capillaries in granulation tissue, and collagen content in scar tissues obviously increased in rh-bFGF-treated groups. Simultaneously, rh-bFGF promoted the differentiation and maturation of regenerated glands around ulcers. rh-bFGF 2-4 kU.kg-1 s.c. also increased the synthesis of RNA in ulcer tissues. In acute gastric ulcers, rh-bFGF i.g. was only effective on pylorus ligated ulcers, but showed no effect on total acid output and pepsin activity in gastric juice of rats. CONCLUSION: rh-bFGF promoted the gastric ulcer healing and improved the quality of gastric ulcer healing.

Acetic Acid↗
PubMed1999

[Analysis of heart rate variability during parallel swinging].

OBJECTIVE: To study the pilots' heart rate variability (HRV) characteristic before, during and after parallel swing and the possibility of evaluating vestibule-vegetative nervous reaction under linear acceleration. METHOD: 37 healthy male pilots participated in parallel swing test. Dynamic ECG was recorded for 15 min before, during and after swing, using model MR-4500 Holter recorder. All spectra were estimated from 15 min HRV by autoregressive (AR) modeling method, the model order (8-15) was chosen using automatic program. The ratio of lower-frequency (LF) to high-frequency (HF) power of HRV spectrum (LF/HF) was computed. The relation between change of those ratios in different swing stage and swing time was analysed. RESULT: Ratio of LF to HF during swing was markedly lower than those of before and after swing (P<0.01). CONCLUSION: The vagal nervous activity was markedly increased during swing. There were complexity and versatility in the heart automatic nervous regulation before, during and after swing.

Acceleration↗
PubMed1998

Activation of JNK in the remote myocardium after large myocardial infarction in rats.

A large myocardial infarction (MI) causes a chronic hemodynamic load on the uninjured remote myocardium (RM). This may lead to oxidative stress, activation of stress-induced cell signaling and increase in myocyte apoptosis. MI was produced in 6 rats (INF) while 4 rats underwent sham operation (CON). At four weeks, there was 128% increase in right ventricular hypertrophy in the hearts from INF vs. CON. Western blot analysis showed 3.8 fold increase in JNK phosphorylation within the RM from INF vs. CON, confirmed by a 4.2 fold increase in JNK kinase activity. There was a 52% increase in TBARS within the RM from INF vs. CON, suggesting increased lipid peroxidation. Furthermore, there was a twofold increase in myocyte apoptosis within the RM in INF vs. CON. We conclude that the RM from INF is associated with activation of JNK, increased oxidative stress and enhanced myocyte apoptosis.

Animals↗
PubMed1998

[Angiotensin II type 2 receptor gene deletion does not affect renin-angiotensin system].

It has been postulated that Angiotensin II type 2 receptor (AT2) functionally antagonizes type 1 (AT1) receptor. In the present study, we investigated whether gene deletion of AT2 receptor causes the compensatory chaos of renin-angiotensin system in mice. It was shown that the concentrations of Angiotensin II in plasma and kidney tissues and the expressions of renin and AT1A receptor in the AT2 gene null mice were unchanged, as compared with those in AT2 wild-type mice. This result suggests that gene deletion of AT2 receptor does not markedly impact the stability of renin-angiotensin system and the inductive function of AT2 receptor is compensated in a way remaining to be clarified.

Animals↗
PubMed1997

Protective role of selenium against hepatitis B virus and primary liver cancer in Qidong.

High rates of hepatitis B virus (HBV) infection and primary liver cancer (PLC) are present in Qidong county. Epidemiological surveys demonstrated an inverse association between selenium (Se) level and regional cancer incidence, as well as HBV infection. Four-year animal studies showed that dietary supplement of Se reduced the HBV infection by 77.2% and liver precancerous lesion by 75.8% of ducks, caused by exposure to natural environmental etiologic factors. An intervention trial was undertaken among the general population of 130,471. Individuals in five townships were involved for observation of the preventive effect of Se. The 8-yr follow-up data showed reduced PLC incidence by 35.1% in selenized table salt supplemented vs the nonsupplemented population. On withdrawal of Se from the treated group, PLC incidence rate began to increase. However, the inhibitory response to HBV was sustained during the 3-yr cessation of treatment. The clinical study among 226 Hepatitis B Surface Antigen (HBsAg)-positive persons provided either 200 micrograms of Se in the form of selenized yeast tablet or an identical placebo of yeast tablet daily for 4 yr showed that 7 of 113 subjects were diagnosed as having PLC in the placebo group, whereas no incidence of PLC was found in 113 subjects supplemented with Se. Again on cessation of treatment, PLC developed at a rate comparable to that in the control group, demonstrating that a continuous intake of Se is essential to sustain the chemopreventive effect.

Adult↗
PubMed1997

Antioxidative activity of 4-oxy- and 4-hydroxy-nitroxides in tissues and erythrocytes from rats.

AIM: To compare the activities of antioxidation of 4-oxy- and 4-hydroxy-nitroxides in tissues and RBC from rats. METHODS: The homogenates of liver, heart, and kidneys of rats were used to determine malondialdehyde (MDA) formation using TBA colorimetric method. H2O2-caused hemolysis was measured spectrometrically. Superoxide anion from zymosan-stimulated neutrophils of rats was assayed by NBT reduction method. RESULTS: Nitroxide free radicals OTMPO and HTMPO inhibited MDA generation caused by .OH generation system (MIC 10.5 and 21 mumol.L-1, respectively), antagonized hemolysis induced by H2O2 (MIC: 338 and 168 mumol.L-1, respectively), but did not affect O2- formation from activated neutrophils. 1-Hydroxyl compounds OTMPOH and HTMPOH possessed similarly potent antilipoperoxidative activities. But nonfree radical OTMP and HTMP had no effect on peroxidation of tissues. CONCLUSION: Nitroxides exert their antilipoperoxidative effect by specifically scavenging .OH free radicals in biological system. Trapping of .OH free radicals by nitroxides is not by reduction of NO. group in nitroxides. Both NO. group and NOH group are essential active groups.

Animals↗
PubMed1997

Effects of 2.5 s mouse nerve growth factor on regeneration of injured sciatic nerves in mice and rats.

AIM: To study the promoting activity of 2.5 s murine nerve growth factor (NGF) for the regeneration of injuried sciatic nerve. METHODS: The sciatic nerves of mice and rats were crushed. The axon counts and differential axon counts were made. Evoked potential latency (NMEPL) was recorded at sites of proximal (Pro) and distal (Dis) segment of soleus muscles. RESULTS: In mice, NGF im 0.5-1 kBU.kg-1 increased the axon counts of regenerated nerves 20 d after crush; 2-4 kBU.kg-1 simultaneously alleviated the denervated atrophy of soleus muscles. In rats, NGF i.m. increased the axon counts at dose of 1 kBU.kg-1 for 40 d, 2 kBU.kg-1 for 30 d and 40 d, and 4 kBU.kg-1 for 20 d, 30 d and 40 d after crush; the number of large axons of regenerated nerves were also increased by NGF i.m. 2 kBU.kg-1 for 40 d and 4 kBU.kg-1 for 30 d and 40 d; Pro NMEPL was shortened by NGF 1, 2, and 4 kBU.kg-1, Dis-NMEPL was shortened by NGF 2 and 4 kBU.kg-1 for 40 d. CONCLUSION: NGF im evidently promotes the regeneration of injuried sciatic nerve, and attenuates the skeletal muscular atrophy caused by nerve injury.

Animals↗
PubMed1997

[The study of influencing cellular dynamics of gynostemma pentaphyllum on golden hamster cheek pouch premalignancy]

Studying premalignancy is an important field of conquering cancer.The aim to study the mechanics of oral mucosal premalignant formation and seek effective drug which could prevent and block cancer,Gynostemma Pentaphyllum(GP) was applies to block carcinomatous conversion of golden hamster cheek pouch by Salley's way.Using light microscopic observation and proliferating cell nuclear antigen(PCNA) as well as bromodeoxyuridine(BrdU)(PCNA AND BrdU are immunohistochemistry techniques),GPs effect was observed dynamically.We found that GP could delay the presence of leukoplakia and decrease the rate of presence as well as cancer-causing rate. The positive cells of taking drug group PCNA and BrdU were lower than model group significantly and in a lower condition all the time.It is illustrated that GP has the effect of preventing cancer and inhibiting cellular dysplasia.

Journal Article↗
PubMed1996

[Observation of the effectiveness of compound Gynostemma Pentaphyllum Mak in golden hamster cheek pouch's premalignancy]

Premalignant model was established successfully in this study.At the same time,we applied compound Gynostemma Pentaphyllum Mak to conduct experimental research to block development of oral mucosal premalignancy.The results showed from uniform to granular or verrucous leukoplakia,there was the stage in which Gynostemma Pentaphyllum Mak could block oral mucosal premalignancies.The group which was firstly given to Gynostemma Pentaphllum Mak then smeared was more advantageous than the one which firstly smeared then given to the same drug.The experimentation demonstrated that Gynostemma Pentaphyllum had the functions of preventing and resisting cancer.There will be applied prospect in preventing and treating oral mucosal premalignancy.We should make further research in the future.

Journal Article↗
PubMed1995

Radon entry control in new house construction.

People exposed to high concentration levels of radon face an increased risk of developing lung cancer. The risk is directly proportional to the length and level of radon exposure. Because of health reasons, it is safer to build new houses with radon mitigation systems installed in slab-on-grade houses. However, the interrelationships between parameters and factors governing radon entry and control are highly complex. A study performed by the University of Florida has examined the effectiveness of different radon entry control approaches. The analysis was based on 47 houses from three research projects conducted by the University of Florida (14 houses), Florida Solar Energy Center (13 houses), and GEOMET Technologies (20 houses). The evaluation of the performance and effectiveness of improved floor slabs, space conditioning, and ventilating systems were analyzed. Statistical analyses of the interrelationship between various parameters were also performed. Study findings such as the important factors in reducing radon entry and the effectiveness of passive construction approach and active subslab depressurization systems are presented in this paper.

Air Conditioning↗
PubMed1995

[Effect of Epimedium sagittatum on quality of life and cellular immunity in patients of hemodialysis maintenance].

Our previous study had demonstrated that Chinese medicine Epimedium Sagittatum (ES) exerted immuno-enhancing effect on the animal model of chronic renal insufficiency. In present study, we investigated the therapeutic effect of ES on patients of hemodialysis maintenance. 22 cases of regular hemodialytic patients were treated with ES in the form of decoction. 12 patients with hemodialysis were served as controls. It was found that ES had sexual potentiation effect and improved the quality of life in the patients of chronic renal failure with regular hemodialysis. Interleukin 2 (IL-2) activity of peripheral blood monocytes (PBMC) stimulated by PHA was increased significantly in the patients treated with ES. It was suggested that Chinese medicine ES had therapeutic effect on sexual disorder and immunologic inadequacy in the patients of chronic renal failure undergoing hemodialysis.

Adjuvants, Immunologic↗
PubMed1992

[Preliminary observations on effect of selenium yeast on high risk populations with primary liver cancer].

Two populations with high risk primary liver cancer (PLC), one of 226 cases with HBsAg carriers and another of 3849 first-relatives in the pedigree with high incidence of PLC, were randomly divided into the supplementing selenium group (selenium yeast 200 g Se1Tab/day) and the control group (common yeast 1 Tab/day), and were followed-up for four years and two years respectively. In the population with HBsAg carriers, no liver cancer occurred in the supplementing selenium group; where as the liver cancer incidence rate was 1573.03/10(5) in the control group. Among the first relatives. The liver cancer incidence rate in the supplementing selenium group was 219.37/10(5); and 553.15/10(5) in the control group. The results showed that the incidence of PLC in the supplementing selenium group was significantly lower than in the control group. This study indicates that selenium has distinct anti-PLC effect.

Adolescent↗