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Biomedical subjects

H Wei

Publications and source records attributed to H Wei.

At least 91 records · Page 5Linked to original sources
PubMed2000

The fumonisin B1 content in corn from North China, a high-risk area of esophageal cancer.

Fusarium moniliforme is the primary fungus contaminating corn throughout the world. Fumonisin B1 (FB1) is the major metabolite of F. moniliforme. It has been shown that FB1 is the promoter and initiator of liver cancer in rat. The corn of Cixian, in Hebei Province, the high-risk area for esophageal cancer in China, is often contaminated by this fungus. A total of 21 corn samples were collected from households in the Cixian County. High levels of FB1 (88.90+/-13.1 microg/g) were found in 10 moldy samples, and low levels (1.40+/-0.50 microg/g) of FB1 were found in 11 apparently healthy corn samples. The positive detection rates of FB1 in moldy and normal samples were 100 and 90.9%, respectively. The frequency of FB1 contamination in the high-risk area is about twice that in the low-risk areas, and the average content of FB1 in samples from high-risk areas was approximately three times that from low-risk areas. Our data indicate that FB1-contaminated corn may be involved in the carcinogenesis of esophageal cancer in high-risk areas of North China.

Carboxylic Acids↗
PubMed2000

Effects of angiotensin II receptor blockade on hepatic fibrosis in rats.

OBJECTIVE: To investigate the effects of angiotensin II type 1 receptor blockade, losartan, on serum levels of components of extracellular matrix in experimental fibrotic rats. METHODS: Fifty male Spague-Dawley rats were separated into five groups (control, model, and 3 treatment groups). Excepting rats in control group, all rats were given subcutaneous injection of 40% carbon tetrachloride (once every 3 days for 6 weeks). Rats in 3 treatment groups were also given losartan of 10mg/kg, 5mg/kg, 2.5mg/kg daily for 6 weeks via gastrogavage, respectively. At the end of sixth week, all rats were sacrificed. Radioimmunoassay was performed to determine the serum levels of hyaluronic acid (HA), Laminin (LN), procollagen type III (PCIII) and collagen type IV. Van Giesion collagen staining was used to evaluate the extracellular matrix of the liver tissue. RESULTS: Compared with model group, losartan significantly reduced the serum levels of HA [from (911.66 +/- 345.49)microg/L to (425.05 +/- 115.80)microg/L], LN [from (209.87 +/- 91.57)microg/L to (83.56 +/- 22.12)microg/L, PCIII [from (31.82 +/- 6.90)microg/L to (22.78 +/- 8.38)microg/L] and collagen IV [from (54.09 +/- 19.81)microg/L to (30.51 +/- 12.39)microg/L] (P<0.05) and greatly attenuated the degree of liver fibrosis (P<0.05). CONCLUSION: Losartan can markedly reduce the serum levels of LN, HA, PCIII and collagen type IV of fibrotic rats induced by CCl(4) and greatly attenuate the degree of liver fibrosis.

Angiotensin Receptor Antagonists↗
PubMed2000

Swelling-activated chloride currents in embryonic chick heart cells.

AIM: To characterize a swelling-activated chloride current, I(Cl, swell), in white Leghorn chick heart cells and the effects of chlorpromazine (CPZ) effects. METHODS: The patch-clamp technique in the whole-cell configuration was used. RESULTS: Hyposmotic swelling elicited I(Cl, swell) in white Leghorn chick heart cells. The current amplitude increased from (452 +/- 200) pA to (849 +/- 373) pA with a reduction of osmolarity from 300 mmol.L-1 to 270 mmol.L-1, 4',4-Diisothiocyanostilbene-2,2'-disulphonic acid (DIDS) 100 mumol.L-1 decreased I(Cl, swell) from (1196 +/- 505) pA to (830 +/- 328) pA in hyposmotic solution. In white Leghorn chick heart cells I(Cl, swell) was not induced by CPZ 30 mumol.L-1, which is different from the case of E coli spheroplast. CONCLUSION: Swelling-activated chloride current was activated by hyposmotic swelling in white Leghorn chick heart cells. The mechanism for activating the current is different from that of mechanosensitive ion channels of E coli.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2000

Emodin on hepatic fibrosis in rats.

OBJECTIVE: To investigate effect of emodin on hepatic fibrosis in rats. METHODS: The rat hepatic fibrosis model was induced by the subcutaneous injection of 40% CCl4 (twice a week for 6 weeks) dissolved in olive oil. The emodin-treated rats were treated with low-dose, mediate-dose and high-dose emodin (20, 40 and 80 mg/kg body weight, once a day for 42 days) dissolved in 0.5% sodium carboxymethylcellulose (CMC), except receiving CCl4. Control group received only olive oil and 0.5% CMC. Liver functions were determined by standard procedure. Serum hyaluronic acid and laminin were determined by radioimmunoassay. Liver hydroxyprolines were determined. Histopathological changes were examined by optical microscopy. RESULTS: Compared with model group, the emodin-treated rats showed (1) liver functions were improved, alanine transaminase (ALT) and alkaline phosphatase (AKP) were obviously reduced, and total protein (TP) and albumin (ALB) were significantly increased; (2) serum hyaluronic acid and laminin were markedly reduced; (3) liver hydroxyproline was significantly decreased; (4) the degrees of fibrosis were reduced. The changes of parameters mentioned above were significant (P < 0.05 or P < 0.01). CONCLUSION: Emodin has effect on hepatic fibrosis in rats. The hepatoprotective of emodin may be one of mechanisms for liver fibrosis.

Animals↗
PubMed2000

[Effect of emodin on development of hepatic fibrosis in rats].

OBJECTIVE: To investigate the effect of emodin on the development of hepatic fibrosis in rats. METHODS: Forty percent of carbon tetrachloride (CCl4) dissolved in olive oil was injected subcutaneously to rats twice a week, for 6 weeks to produce hepatic fibrosis model, the rats of treated group were simultaneously injected with CCl4, treated with emodin in low, medium and high dose (20, 40 and 80 mg/kg body weight respectively) once a day for 42 days, which was dissolved in 0.5% sodium carboxymethylcellulose (CMC), while for rats of the control group, they only received CCl4 and CMC. Changes of serum hyaluronic acid, laminin and liver hydroxyproline were determined and histopathologic changes of liver was examined by optical microscopy and electronmicroscopy. RESULTS: Compared with the model group, in the emodin treated group: (1) Serum hyaluronic acid and laminin were markedly reduced (P < 0.05 or 0.01); (2) liver hydroxyproline was significantly decreased (P < 0.05 or 0.01); (3) degree of fibrosis was reduced (P < 0.05 or 0.01); (4) hepatocyte injury was ameliorated. CONCLUSION: Emodin has therapeutic effect on the development of hepatic fibrosis in rats. The effect might be related to slowing hepatocyte injury.

Animals↗
PubMed2000

A study of toxic effect of mitomycin C on cultured bovine trabecular meshwork cells.

PURPOSE: To explore the toxicity of Mitomycin C (MMC) on trabecular meshwork cells. METHODS: Bovine trabecular meshwork cells were cultured in vitro and exposed to MMC of different concentrations. The cellular morphology, ultrastructure, mortality and phagocytosis was studied with light microscopy, transmission electron microscopy and methods of Wright's stain, etc. RESULTS: It was found that the toxic effect of MMC on the cells was in a dose-dependent mode. 1 x 10(-2) and 1 x 10(-3) mg/ml of MMC caused a large part of cells dead, 1 x 10(-4) and 1 x 10(-5) mg/ml of the drug had remarkable killing effect on the cells. 1 x 10(-6) mg/ml of MMC had still a mild toxicity, while 1 x 10(-7) mg/ml of MMC had not any influence on cellular morphology, mortality, and phagocytosis, etc. The safe concentration on bovine trabecular meshwork cells was 1 x 10(-7) mg/ml and the LD50 was between 1 x 10(-3) and 1 x 10(-4) mg/ml. CONCLUSIONS: Refering to previous data, we conclude that conventional clinical-application of MMC might do harm to trabecular meshwork cells.

Animals↗
PubMed1999

Involvement of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and p53 in neuronal apoptosis: evidence that GAPDH is upregulated by p53.

We recently reported that cytosine arabinoside (AraC)-induced apoptosis of cerebellar neurons involves the overexpression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The present study was undertaken to investigate whether p53 and/or Bax overexpression participates in the AraC-induced apoptosis of cerebellar granule cells and, if so, the relationship between p53 induction and GAPDH overexpression in these cells. AraC-induced apoptosis of cerebellar granule cells was preceded by an increase in levels of p53 mRNA and protein detected between 1 and 8 hr after treatment. The mRNA level for a p53 target gene, Bax, was also increased. The increase in GAPDH mRNA lasted longer than that of either p53 or Bax, and the level of GAPDH protein in the particulate fraction increased after induction of GAPDH mRNA. The antisense oligonucleotide to p53 protected granule cells from AraC-induced chromatin condensation, internucleosomal cleavage, and apoptotic death. The inhibition of p53 expression by the p53 antisense oligonucleotide not only blocked the expression of Bax but also partially suppressed the increased GAPDH mRNA and protein levels. Conversely, the suppression of GAPDH expression and subsequent attenuation of apoptosis of granule cells by GAPDH antisense oligonucleotide did not influence the expression of p53 or Bax. Cerebellar granule cells prepared from p53 knock-out mice were resistant to AraC toxicity, and the p53 gene knock-out suppressed AraC-upregulated GAPDH expression. Moreover, infection of PC12 cells with an adenoviral vector containing p53 gene dramatically increased GAPDH expression and triggered cell apoptosis. These results suggest that AraC-induced apoptosis of cerebellar granule cells involves the expression of both GAPDH and p53 and that, similar to Bax, GAPDH is upregulated by p53 after exposure to the apoptotic insult.

Animals↗
PubMed1999

MK-801, an NMDA receptor antagonist, in the rostroventromedial medulla attenuates development of neuropathic symptoms in the rat.

Segmental ligation of spinal nerves in the rat induces a long-lasting hyperalgesia and allodynia that mimicks neuropathic conditions in humans. In the present study we attempted to determine whether supraspinal NMDA receptors contribute to the induction of the long-lasting hypersensitivity to noxious and innocuous mechanical stimulation following segmental ligation of spinal nerves in the rat. MK-801, an NMDA receptor antagonist, was microinjected into the rostroventromedial medulla (RVM) 15 min before or 25 min after the ligation of spinal nerves and mechanical hypersensitivity was assessed at various time points following surgery by determining the hindlimb withdrawal threshold to noxious and innocuous mechanical stimulation. A single dose of MK-801 administered prior to nerve ligation into the RVM significantly attenuated the development of mechanical hypersensitivity throughout the 2 week postoperative observation period, whereas corresponding administration of MK-801 immediately after the nerve ligation attenuated the development of mechanical hypersensitivity only during the first postoperative day but not later. The results indicate that NMDA receptors in the RVM are involved in triggering the enhanced sensitivity to mechanical stimulation induced by a nerve injury.

Animals↗
PubMed1999

Identification and characterization of receptor for mammalian hepatopoietin that is homologous to yeast ERV1.

Hepatopoietin (HPO) is a novel polypeptide mitogen specific for hepatocytes and hepatoma cell lines, which is derived from liver and supports its regeneration. To determine whether HPO acts via a receptor-based signal transduction, recombinant human hepatopoietin was labeled by iodination and used to characterize its binding activity by specific displacement test and Scatchard analysis in primarily cultured rat hepatocytes and human hepatoma Hep-G2 cells. The binding was saturable and specific because it was replaceable by HPO but not by epidermal growth factor, transforming growth factor-alpha, or insulin. Scatchard analysis indicated the presence of a single class of high affinity receptor with dissociation constant (Kd) of 2 and 0.7 pM, and a receptor density of about 10, 000 sites/cell and 55,000 sites/cell in the rat hepatocytes and human hepatoma cells, respectively. The Kd values were consistent with the half-maximum dose of HPO activity. Affinity cross-linking of the receptor with 125I-HPO revealed a polypeptide of molecular mass approximately 90 kDa by SDS-polyacrylamide gel electrophoresis. Thus, the molecular mass of the HPO receptor was calculated to be about 75 kDa. These data demonstrated the existence of an HPO receptor in hepatocytes and hepatoma cells, which may account for biological effect.

Animals↗
PubMed1999

Effects of hydrostatic pressure on cultured bovine trabecular meshwork cells.

In order to explore the effects of pressure on trabecular meshwork cells, bovine trabecular meshwork cells were cultured in vitro and subjected to different levels of hydrostatic pressure. The cellular morphology, ultrastructure and phagocytosis were studied with inverted phase-contrast microscopy, light microscopy and transmission electron microscopy, etc. It was found that the cells subjected to 2.0 kPa or 2.67 kPa for 48 h had no remarkable difference as compared with the controls in terms of parameters observed. Those under 4.0 kPa for 24 h showed slight changes in structure and a mild decrease in phagocytic function. The damage appeared more severe if the pressure was higher or lasted longer. From the above we conclude that trabecular meshwork cells can only bear pressure below a certain level. They may be destroyed structurally or impaired functionally by pressure over this level.

Animals↗
PubMed1999

Growth-promoting effect of recombinant human growth hormone and stanozolol in girls with Turner syndrome.

Ten girls with Turner syndrome were treated with a combination therapy of recombinant human growth hormone (R-hGH) and low dose stanozolol for a period of 8 to 36 months. The results showed that when compared with the growth rate before the treatment, the growth rates after treatment with R-hGH and stanozolol showed a sustained increase, reaching 9.0 +/- 1.9 cm/year during the first year of treatment; the height age increase by 2.5 +/- 0.8 years while the bone age increase were 1.0 +/- 0.7 years; and the predicted final adult height at the end of the first year of the treatment increased to 149.4 +/- 6.1 cm compared to their original mean of 142.8 +/- 4.2 cm. We are led to conclude that therapy with R-hGH in combination with stanozolol can increase the growth velocity and significantly increase the predicted adult height of children with Turner syndrome.

Adolescent↗
PubMed1999

Spinal nerve ligation-induced neuropathy in the rat: sensory disorders and correlation between histology of the peripheral nerves.

We studied the effect of unilateral ligation of two spinal nerves on behavioral pain responses evoked by various types of cutaneous stimuli in the adult rat. Furthermore, we determined the effect of spinal nerve ligation on morphology of the peripheral nerves. The most consistent behavioral finding (83%) was a marked decrease in monofilament-induced hindlimb withdrawal thresholds (mechanical allodynia) ipsilateral to the spinal nerve ligation. This mechanical allodynia was observed as early as during the 1st post-operative day and it persisted up to 2 months (the maximum length of the observation period). In contrast, hyperalgesia to noxious mechanical stimulation (Randal-Sellitto test) was not observed in allodynic rats until the 3rd post-operative day. In a minority of rats (13%), spinal nerve ligation-induced mechanical hyperalgesia without a concomitant mechanical allodynia. There was no corresponding heat hyperalgesia in the injured hindlimb (hot water immersion-, radiant heat- or hot-plate-induced hindlimb withdrawal tests). In contrast, hypoalgesia to heat was observed on the 1st postoperative day, but not later. Neuropathological analysis of the peripheral nerves revealed a dramatic decrease in the number of myelinated nerve fibers distal to the spinal nerve ligation site. The results support the previous evidence indicating that ligation of spinal nerves induces a marked allodynia to mechanical stimulation. However, this mechanical allodynia may differentially dissociate from mechanical and thermal hyperalgesia at various post-operative time points. The marked mechanical allodynia together with a dramatic decrease in the number of myelinated nerve fibers is paradoxical, since the activation of myelinated nerve fibers by monofilaments produced abnormally strong behavioral responses. This paradox may be explained by spinal nerve ligation-induced amplification or disinhibition of tactile signals at central levels.

Animals↗
PubMed1999

Scavenging of hydrogen peroxide and inhibition of ultraviolet light-induced oxidative DNA damage by aqueous extracts from green and black teas.

Aqueous extracts of green and black teas have been shown to inhibit a variety of experimentally induced animal tumors, particularly ultraviolet (UV) B light-induced skin carcinogenesis. In the present study, we compared the effects of different extractable fractions of green and black teas on scavenging hydrogen peroxide (H2O2), and UV irradiation-induced formation of 8-hydroxy 2'-deoxyguanosine (8-OHdG) in vitro. Green and black teas have been extracted by serial chloroform, ethyl acetate and n-butanol, and divided into four subfractions designated as GT1-4 for green tea and BT1-4 for black tea, respectively. The total extracts from green and black teas exhibited a potent scavenging capacity of exogenous H2O2 in a dose-dependent manner. It appeared that the total extracts from black tea scavenged H2O2 more potently than those from green tea. When tested individually, the potency of scavenging H2O2 by green tea subfractions was: GT2 > GT3 > GT1 > GT4, whereas the order of efficacy for black tea was: BT2 > BT3 > BT4 > BT1. In addition, we demonstrated that total fractions of green and black teas substantially inhibited the induction of 8-OHdG in calf thymus by all three portions of UV spectrum (UVA, B and C). Consistent with the capacity of scavenging H2O2, the subfractions from black tea showed a greater inhibition of UV-induced 8-OHdG than those from green tea. At low concentrations, the order of potency of quenching of 8-OHdG by green tea subfractions was: GT2 > GT3 > GT4 > GT1 and the efficacy of all subfractions became similar at high concentrations. All subfractions of the black tea except BT1 strongly inhibited UV-induced 8-OHdG and the order of potency was: BT2 > BT3 > BT4 > BT1. Addition of (-)-epigallocatechin gallate (EGCG), an ingredient of green tea extract, to low concentration of green and black tea extracts substantially enhanced the scavenging of H2O2 and quenching of 8-OHdG, suggesting the important role of EGCG in the antioxidant activities of tea extracts. The potent scavenging of oxygen species and blocking of UV-induced oxidative DNA damage may, at least in part, explain the mechanism(s) by which green/black teas inhibit photocarcinogenesis.

Carcinogenicity Tests↗
PubMed1999

PUVA (8-methoxy-psoralen plus ultraviolet A) induces the formation of 8-hydroxy-2'-deoxyguanosine and DNA fragmentation in calf thymus DNA and human epidermoid carcinoma cells.

The objective of this study is to investigate if 8-methoxy-psoralen (8-MOP) plus ultraviolet A (UVA) radiation (PUVA) induces oxidative DNA damage. When calf thymus DNA was incubated with 8-MOP and irradiated with UVA (335-400 nm), the level of 8-hydroxy-2'-deoxyguanosine (8-OHdG) was substantially increased by approximately 6-fold. Formation of 8-OHdG proportionally correlated with both UVA fluence and 8-MOP concentrations. Human epidermoid carcinoma cells were incubated with 10 microg 8-MOP per milliliter, followed by irradiation of 25 kJ/m2 UVA. The level of 8-OHdG increased by nearly 3-fold in PUVA-treated cells compared to 8-MOP and UVA controls. The formation of 8-OHdG correlated with DNA fragmentation as determined by spectrofluorometry. To investigate the reactive oxygen species (ROS) involved in PUVA-induced oxidative DNA damage, less or more specific ROS quenchers were added to DNA solution prior to PUVA treatment. The results showed that only sodium azide and genistein significantly quenched PUVA-induced 8-OHdG, whereas catalase, superoxide dismutase, and mannitol exhibited no effect. The quencher study with cultured cells indicated that N-acetyl-cysteine and genistein protected oxidative DNA damage as well as DNA fragmentation by PUVA treatment. Our studies show that PUVA treatment is able to induce the formation of 8-OHdG in purified DNA and cultured cells and suggest that singlet oxygen is the principle reactive oxygen species involved in oxidative DNA damage by PUVA treatment.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Alcohol consumption and alcohol-related problems: Chinese experience from six area samples, 1994.

AIMS: To understand the drinking frequency, mean yearly volume of consumption and drinking-related problems in individuals living in six areas in China. DESIGN AND MEASUREMENTS: By two-stage sampling, 23,513 community household residents (15-65 years old) were assessed with data collected by trained psychiatrists using structured questionnaires and DSM-III-R criteria. FINDINGS: The male, female and total drinking rates were 84.1%, 29.3% and 59.5%, respectively. More than half of male drinkers and 90.0% of female drinkers used alcohol once a week or less. More than 16.1% of male drinkers and 2.5% of female drinkers drank once a day or more. The males reported a greater amount of alcohol consumed per session. The mean yearly volume of consumption of pure alcohol per year for all sample was 3.60 l; males consumed 18.6 times more alcohol than females. The rate of alcohol-related problems was higher in males than females. The male, female and total alcohol dependence point prevalence rates were 6.632%, 0.104% and 3.428%, respectively. Six-month incidence rates of acute intoxication were 5.162% 0.017% and 2.637%, respectively. CONCLUSION: Drinking problems in China will continue to be a public health problem in the next century.

Adolescent↗
PubMed1999

Effects of bull, sperm type and sperm pretreatment on male pronuclear formation after intracytoplasmic sperm injection in cattle.

This study investigated the effects of the bull, sperm type (dead, immotile or motile) and sperm pretreatment (i.e. mechanical (tail-cutting or tail-scoring) or chemical (heparin, heparin + caffeine, calcium ionophore A23187 or dithiothreitol)) on male pronuclear formation after intracytoplasmic sperm injection (ICSI) in cattle. Three experiments were conducted. In Experiment 1, spermatozoa from three bulls (A, B and C) were used for both ICSI and in vitro fertilization (IVF). The results were that sperm from bull B yielded a higher penetration/male pronuclear formation rate than that of bull C when used for IVF (89.6% v 25.6%, P<0.01). However, when injected into oocytes by ICSI, sperm from bull C had a higher male pronuclear formation rate than that of bull B (34.6% v. 16.1%, P<0.05). The effects of sperm type and mechanical pretreatment were examined in Experiment 2. No significant difference was found in the male pronuclear formation rate when the three types of sperm were injected into oocytes. Tail-scored sperm achieved a higher male pronuclear rate than that of non-mechanically treated ones (38.2% v. 13.2%, P<0.005). In Experiment 3, chemical pretreatments were tested and compared. Higher male pronuclear rates, compared with the control, were obtained when sperm were pretreated with heparin + caffeine, calcium ionophore A23187 and dithiothreitol (48.2%, 62.5% and 64.5% v. 25.0%, P<0.05, 0.005 and 0.005, respectively). These results indicate that (1) there is a bull variation in male pronuclear formation with ICSI, and the male pronuclear rate by ICSI is not coincident with the results by IVF, (2) immobilization of a spermatozoon by tail-scoring before ICSI can improve the formation of the male pronucleus, and (3) an appropriate chemical pretreatment of spermatozoa is necessary to achieve a higher rate of male pronuclear formation.

Animals↗