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Biomedical subjects

H Wei

Publications and source records attributed to H Wei.

At least 181 records · Page 10Linked to original sources
PubMed1996

Inhibition of UV light- and Fenton reaction-induced oxidative DNA damage by the soybean isoflavone genistein.

We have investigated the effect of the soybean isoflavone genistein on 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in calf thymus DNA exposed to either UV irradiation or the Fenton reaction system. Under the conditions used we observed that UV light and the Fenton reaction significantly increase 8-OHdG formation in DNA. Co-incubation with genistein inhibits the formation of 8-OHdG induced by either UV light irradiation or the Fenton reaction in a dose-dependent manner. The quenching effect of genistein on 8-OHdG formation induced by UV light is much more potent than that by the Fenton reaction, suggesting that the mechanisms of 8-OHdG formation may differ between the two systems. We further compared the antioxidant activities and quenching effect on 8-OHdG formation of genistein with biochanin A. Genistein potently scavenges both hydrogen peroxide in the medium and superoxide anion generated by xanthine/xanthine oxidase, whereas biochanin A has either a weak or no scavenging effect on these reactive oxygen species. However, both genistein and biochanin A display a similar quenching effect on UV light-induced 8-OHdG formation. These results suggest that the quenching effect of genistein and biochanin A on UV light-induced 8-OHdG formation is different from their ability to scavenge hydrogen peroxide and superoxide anion. The potent inhibition of UV light-induced oxidative DNA damage by genistein suggests its potential anticarcinogenic role in photocarcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1996

Indonesian Medicinal Plants. XIV. Characterization of 3'-O-Caffeoylsweroside, a new secoiridoid glucoside, and kelampayosides A and B, two new phenolic apioglucosides, from the bark of Anthocephalus chinensis (Rubiaceae).

A new secoiridoid glucoside named 3'-O-caffeoylsweroside (1), and two new phenolic apioglucosides, named kelampayoside A (4) and kelampayoside B (6), together with eleven known compounds (five iridoids and six alkaloids), were isolated from the bark of Anthocephalus chinensis (Rubiaceae), an Indonesian medicinal plant from Sumatra Island, Indonesia. The chemical structures of 1, 4 and 6 have been elucidated respectively as 3'-O-caffeoylsweroside (1), antiarol 1-O-beta-D-apiofuranosyl (1 --> 6)-beta-D-glucopyranoside (4), and antiarol 1-O-beta-D-5"-O-caffeoylapiofuransoyl (1 --> 6)-beta-D-glucopyranoside (6) on the bases of their chemical and physiochemical properties. Among fourteen constituents characterized, cadambine (13), one of the major indole alkaloid constituents of A. chinensis, was shown to exhibit moderate growth-inhibitory activity against the malarial parasite Plasmodium falciparum (a chloroquine-resistant K1 strain) cultured in human erythrocytes.

Animals↗
PubMed1996

Expression of mesenger RNA for transforming growth factor-beta 1 in bovine trabecular meshwork.

PURPOSE: To investigate the relationship between transforming growth factor-beta 1 (TGF-beta 1) and primary open-angle glaucoma, we have determined whether trabecular tissues have the expression of messenger RNA for TGF-beta 1. METHODS: Total RNA of 24 newborn bovine trabecular tissue were extracted by Guanidine isothiocyanate method. The TGF-beta 33 plasmid was brought into E. colibacillius HB101 and amplificated. After Bam HI endolase degradation and label with alpha-32p-dATP the RNA was hybridized with the cDNA (complementary DNA) probe and examined by autoradiography. RESULTS: The presence of mRNA for TGF-beta 1 in bovine trabecular meshwork was confirmed. CONCLUSIONS: The TGF-beta 1 present in normal aqueous humor must be at least partly derived from the trabecular meshwork. It offered a basis for understanding the relationship between abnormal synthesis, activation and clearance of TGF-beta 1 and the pathogenesis of primary open-angle glaucoma (POAG) in molecular biology.

Animals↗
PubMed1996

[Inhibitory effects of gypenoside on rat heart and brain Na+, K+(-)ATPase activity].

The effects of gypenoside (Gyp) on the microsomal Na+, K(+)-ATPase from rat hearts and brains were investigated in comparison with ginsenoside (Gin). The results showed that Gyp could inhibit the enzyme activity rapidly and reversibly in vitro. The inhibition was in a concentration-depend manner. The IC50 of Gyp for the heart and brain was 58.79 +/- 8.05 mg/L and 52.07 +/- 6.25 mg/L, respectively. Kinetic analysis revealed that Gyp was an incompetitive inhibitor of ATP. These results suggest that the positive inotrope effect and the inhibition of CNS by Gyp are related to the in hibitory action of Gyp on the actiyily of Na+, K(+)-ATPase from hearts or brains.

Animals↗
PubMed1996

[A study of 5-fluorouracil on bovine trabecular meshwork cells in vitro].

OBJECTIVE: To determine whether the clinical use of 5-fluorouracil (5-FU) may have any toxic effects on trabecular meshwork cells. METHODS: Bovine trabecular meshwork (BTM) cells were cultured in vitro. The effects of 5-FU on BTM cells concerning cellular morphology, ultrastructure, vitality and phagocytosis were observed. RESULT: The safe dosage of 5-FU on BTM cell was 1 x 10-6g.ml-1. CONCLUSION: Based on the pharmacokinetic data in the rabbit anterior chamber, it is suggested that the 5-FU dosage of conventional use cause no injury to human trabecular meshwork cells.

Animals↗
PubMed1996

[Pearl and mother-of-pearl powder in health-care].

Based on pharmacological studies in files, mice and rats, the powder of sea pearl (Pteria martensii), mother-of-pearl and freshwater pearl has been proved to have tonic, anti-aging and anti-radiative actions. The effect of the sea pearl and mother-of-pearl powder is higher than that of freshwater pearl powder.

Aging↗
PubMed1995

Differential expression of glial fibrillary acidic protein (GFAP) in the retinae and visual cortices of rats with experimental renal hypertension.

To examine the expression of the GFAP protein in the retina and visual cortex under normal and pathological conditions, hypertension was induced in adult male Sprague-Dawley rats by applying silver clips onto renal arteries and the change in GFAP expression was followed by Western blotting and immunocytochemical staining. One week after operation when the induced hypertension was at the initial stage, GFAP expression in the retina was reduced to half of the sham control. By 4 weeks, when consistent hypertension was developed, a further decrease in the level of GFAP expression in the retina to one third of the sham control was observed. Immunocytochemical staining showed that the number of GFAP-positive cells in the nerve fiber layer of the retina of the hypertensive rat was reduced to less than one third of the sham control. However, similar changes in GFAP expression in the visual cortex of hypertensive rats were not observed. This study represents the first report to date on GFAP expression in the retina and visual cortex and includes discussion of the possible mechanisms through which GFAP expression is mediated.

Animals↗
PubMed1995

[Investigation of the contamination of air and environment in the blood dialysis department].

As the blood dialysis has been applied more widely, the hygenic state of air and furniture surfaces in blood dialysis room and that of dialysis fluid would diretly affect the incidence of nosocomial infections. The results of investigation in three hospital dialysis units showed that: With people walking around, the number of air microbes presented a kenetic variation, ranged from 410 to 1755CFU/m3. That number was positively related to the number of dust particles in the air, which carring certain amount pathogenic of conditional-pathogenic microbes, among which, fungi, Stap. aureus and Pseud. aruginosa acount for 8.38%, 2.99% and 1.39% respectively. Physical of chemical disinfection treatment showed prompt effects (P < 0.01). The thermogenic reaction and infections in dialysis patients were mainly due to microbes containminated in the water for dialysis. Some of these microbes may produce intracellular or and exo-toxin and thermogenic factors. The microbes in dialysis machines could 100% be killed immediately after disinfecting the dialysis tubes with 5% available chlorine. But the germ numer could rise again as the time streched. Our results suggested that certain monitoring and disinfectious procedures must be carried out in hospital critical departments so as to reduce nosocomial infection cases.

Air Microbiology↗
PubMed1995

Effect of left ventricular hypertrophy secondary to chronic pressure overload on transmural myocardial 2-deoxyglucose uptake. A 31P NMR spectroscopic study.

BACKGROUND: This study tested the hypothesis that 31P nuclear magnetic resonance (NMR)-detectable 2-deoxyglucose (2DG) uptake is increased in chronically pressure-overloaded hypertrophied left ventricular myocardium. METHODS AND RESULTS: 31P NMR spectroscopy was used to determine the transmural distribution of high-energy phosphate levels and 2-deoxyglucose-6-phosphate (2DGP) accumulation during intracoronary infusion of 2DG (15 mumol.kg body wt-1.min-1) in eight normal dogs and in eight dogs with severe left ventricular hypertrophy (LVH) produced by ascending aortic banding. The ratio of LV weight to body weight was 8.25 +/- 0.65 g/kg in the LVH group compared with 4.35 +/- 0.11 g/kg in the normal group (P < .01). Myocardial ATP content was decreased by approximately 40% and phosphocreatine (PCr) by approximately 60% in LVH hearts. ATP values were transmurally uniform in LVH and normal hearts, whereas PCr was lower in the subendocardium (Endo) than the subepicardium (Epi) of both groups. The PCr/ATP ratio was lower in LVH hearts (1.72 +/- 0.05, 1.64 +/- 0.07, and 1.53 +/- 0.10 in Epi, midwall, and Endo, respectively) compared with normal hearts (2.36 +/- 0.05, 2.09 +/- 0.06, and 1.96 +/- 0.06; each P < .01 normal versus LVH). Arterial blood levels of glucose, insulin, and free fatty acids were comparable between groups, whereas arterial lactate and norepinephrine levels were significantly higher in the LVH group. 2DG infusion did not affect systemic hemodynamics or myocardial high-energy phosphate or inorganic phosphate levels in either group. At the end of 60 minutes of 2DG infusion, there was no detectable accumulation of 2DGP in the normal hearts. However, seven of the eight LVH hearts showed time-dependent accumulation of 2DGP, which was linearly related to the severity of hypertrophy (r = .90 for subendocardial 2DGP versus LV weight/body weight). A transmural gradient of 2DGP was present, with greatest accumulation in the subendocardium (3.3 +/- 1.6, 5.8 +/- 2.3, and 7.9 +/- 2.2 mumol/g in Epi, midwall, and Endo of the LVH hearts, respectively; P < .05 Epi versus Endo). CONCLUSIONS: The pressure-overloaded hypertrophied left ventricle demonstrated increased accumulation of 2DGP detected with 31P NMR spectroscopy. Accumulation of 2DGP was positively correlated with the degree of hypertrophy and was most marked in the subendocardium.

Adenosine Triphosphate↗
PubMed1995

In vivo formation of DNA-adducts in mouse skin DNA by tamoxifen.

Tamoxifen (TAM)-induced DNA adduct formation in mouse skin was determined by a nuclease P1-enhanced 32P-postlabelling technique. Topical application of TAM significantly induced a number of DNA-adducts in mouse skin in a dose- and time-dependent manner. When SENCAR mice were topically treated with different doses of TAM for 6 h, total DNA adduct levels in skin were increased by 2.5- (1 mumol TAM), 4.5- (5 mumol TAM) and 4.8-fold (10 mumol TAM), respectively. In addition, at least four novel DNA adducts were observed. Time-course studies showed that TAM-induced DNA adducts reach a peak at 6 h post-treatment. However, the pattern of TAM-induced DNA adducts was different from that induced by DMBA (a potent skin carcinogen). TAM has been found to form DNA-adducts in the liver and kidney of rodents. Our work confirms the genotoxic effects observed by other investigators by showing that TAM also causes DNA-adducts formation in mouse skin. Since TAM is widely used for the treatment of breast cancer and currently for chemo-prevention trials, further studies should be conducted to assess the potential risk of long-term use of TAM in humans.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

A search for genes from the dark band regions of human chromosome 21.

As part of an effort to isolate genes from the entire long arm of human chromosome 21, we performed cDNA selection with 15 YACs from the regions of the pericentromeric heterochromatin and the two Giemsa dark bands of this chromosome using cDNA libraries from six different tissues. Nine of these YACs mapped to the Giemsa dark band, 21q21. The 9 YACs cover approximately 6 Mb of DNA, representing 15% of 21q and a significant portion of the 12-15 Mb estimated to be within this band. Several lines of evidence from analysis of the selected cDNA libraries suggest that this region of 21q has very few single-copy transcribed sequences. An EcoRI library was constructed with DNA from 1 of the 9 YACs. Grail analysis of the sequences of both ends of 24 YAC-specific clones from this EcoRI library revealed no potential exons. In contrast to these results, the selected cDNA libraries of a control YAC from the human MHC region in 6p21.3 as well as those from most of the other 21q YACs consisted largely of YAC-specific single-copy cDNA clones. Given the success of the cDNA selection method for finding a large number of genes in YACs from other chromosomal regions, these results suggest that the 6 Mb of DNA in the dark band 21q21 contains few single-copy sequences expressed in this tissue set. In contrast, selected cDNA libraries from the pericentromeric region, the telomeric border of the dark band 21q21, and the dark band 21q22.2 yielded more than 30 new ESTs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Beta-adrenergic receptor function in cultured AT-1 cardiomyocytes.

AT-1 cells are highly differentiated, contracting cardiomyocytes derived from atrial tumours in transgenic mice. The aim of this study was to characterize beta-adrenergic receptor function and associated intracellular calcium regulation in AT-1 cells. Equilibrium binding experiments with [3H]-CGP-12177 showed a Kd = 0.30 +/- 0.08nM and a Bmax = 2.25 +/- 0.47 fmol/10(5) cells. Competition binding experiments with CGP-20712A showed presence of predominantly beta 1-adrenoreceptors. S-(-)propranolol, atenolol and R-(+)propranolol showed a competitive inhibition of binding with successively lower affinity. Isoproterenol, 2 microM, for 48 hours down-regulated the number (p < 0.05) of beta-adrenergic receptors/cell by about 50%; 10 microM for one hour increased the cAMP concentration (p < 0.05) by about 100%. Cytosolic [Ca2+] was measured flourimetrically in spontaneously and synchronously beating AT-1 cells. The resting cytosolic concentration was 94 +/- 10 nM. The observed sinusoidal Ca2+ oscillation frequency increased after addition of 10 microM isoproterenol (p < 0.02). This effect was antagonized by 10 microM alprenolol (p < 0.01). In conclusion, AT-1 cells have functional beta-adrenoreceptor signalling pathways and constitute an important tool in cardiac biology.

Adrenergic beta-Antagonists↗
PubMed1995

Unidirectional valve patch for repair of cardiac septal defects with pulmonary hypertension.

BACKGROUND: Congenital septal defects with a large left-to-right shunt often cause pulmonary hypertension, which complicates surgical repair of the defects. METHODS: Twenty-four patients with congenital cardiac septal defects and severe pulmonary hypertension had operation to close the septal defect using a unidirectional valve patch during a 3-year period. The ratio of systolic pulmonary artery pressure to systolic arterial blood pressure was near to or more than 1.0 in all patients. RESULTS: Two patients died in the hospital after operation, and there have been no deaths during intermediate term follow-up. Mean pulmonary artery pressure decreased from 80 +/- 12 mm Hg to 56 +/- 18 mm Hg. The ratio of pulmonary artery pressure to systemic arterial pressure dropped from 1.1 +/- 0.1 mm Hg to 0.7 +/- 0.1 mm Hg. The unidirectional valve patch functioned allowing right to left shunting in 4 patients with a systolic pulmonary artery pressure more than systolic arterial blood pressure immediately after closure of a septal defect. The patch sealed or was effectively closed by the third postoperative day. There was impressive improvement in symptoms and exercise tolerance after operation during the 3-month to 3-year (mean, 1.1 year) follow-up period. CONCLUSIONS: The unidirectional valve patch is useful for management of patients having operation to close cardiac septal defects in the presence of severe pulmonary hypertension.

Adolescent↗
PubMed1995

7,12-dimethylbenz[a]anthracene induces oxidative DNA modification in vivo.

Initiation and promotion are major stages in the multistage carcinogenesis process. Formation of initiating carcinogen-DNA base adducts leads to heritable genetic changes, but the tumor-promoting events induced by complete carcinogens have not, as yet, been elucidated. Oxidant production and oxidative DNA damage induced by phorbol esters (i.e., 12-O-tetradecanoyl-phorbol-13-acetate) are associated with tumor promotion, while antioxidants and inhibitors of oxidative DNA damage suppress promotion and carcinogenesis. Our goal was to establish whether a carcinogen that requires oxidative metabolism for its activity can also induce oxidant production and DNA base oxidation. We found that topical treatment of SENCAR mice with 7,12-dimethylbenz[a]anthracene, which induces tumors in 40-50% of the mice, also causes hydrogen peroxide production and formation of oxidized bases (i.e., 8-hydroxyl-2'-deoxyguanosine and 5-hydroxymethyl-2'-deoxyuridine) in epidermal DNA. The levels of oxidized bases were of comparable magnitude to those mediated by the potent tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. The oxidized bases persisted over several weeks in epidermal DNA. These oxidative events appear to be temporally associated with inflammatory responses that include edema and polymorphonuclear leukocyte infiltration, which remained elevated over longer periods of time and at higher levels than those induced by phorbol ester. Because these processes are usually associated with tumor promotion, our results support the conjecture that oxidative events may be involved in what is operationally referred to as the tumor promotion process by 7,12-dimethylbenz[a]anthracene.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1995

Effects of caloric restriction on age-related oxidative modifications of macromolecules and lymphocyte proliferation in rats.

Decreased immune function associated with aging has been demonstrated in both humans and animals. We hypothesize that reactive oxygen species (ROS)-mediated damage to biological macromolecules may contribute to compromised immune response during aging. In this study, we compared the levels of lipid peroxidation and oxidatively modified proteins in plasma and splenocytes, and the mitogen-induced T lymphocyte proliferation in ad lib-fed (AL) and caloric restricted (CR) Fischer 344 x BNF1 male rats at the ages of 5, 18, and 31 months. The results show that AL rats exhibit an age-related decrease in proliferative response of splenic lymphocytes to phytohemagglutinin (PHA) and concanavalin A (Con A). This functional decline in T-lymphocytes during aging is inversely correlated to the levels of both lipid peroxidation and protein carbonyl in the plasma and splenic lymphocytes. Caloric restriction, however, can partially reverse the age-dependent decrease in T lymphocyte proliferation and significantly reduce lipid peroxidation and protein carbonyl contents in plasma and splenocytes. The above observations support the hypothesis that the age-associated declines in immune function are related to the oxidative modification of biological macromolecules, which in turn may lead to enzyme inactivation, membrane disruption, and cell senescence. One of the mechanisms by which caloric restriction reverses declined immune function in aged rats is hypothesized to be through reduction in ROS production and thereby protection of cellular macromolecules against oxidative damage.

Aging↗