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Biomedical subjects

W Liu

Publications and source records attributed to W Liu.

At least 595 records · Page 33Linked to original sources
PubMed1998

Aldosterone responsiveness of A6 cells is restored by cloned rat mineralocorticoid receptor.

A6 cells, derived from Xenopus laevis renal tubule, form a high-resistance ion-transporting monolayer when grown on permeable supports and can generate a short-circuit current (SCC) that is stimulated by high levels of the mineralocorticoid aldosterone. Surprisingly, A6 SCC is more responsive to glucocorticoids than to mineralocorticoids, suggesting the possibility that these cells do not contain transcriptionally active mineralocorticoid receptor (MR) and that glucocorticoid receptor (GR) mediates MR-like responses in these collecting duct-like cells. We have examined the response of both SCC and a transfected reporter gene to mineralocorticoids and glucocorticoids in the presence and absence of transfected rat MR (rMR). We found that, in the absence of transfected MR, a reporter gene that can be activated by MR or GR was more responsive to glucocorticoids such as dexamethasone and RU-28362 than to mineralocorticoids such as aldosterone. Transfected rMR underwent mineralocorticoid-dependent nuclear localization and restored both transcriptional sensitivity of a reporter gene and SCC response to mineralocorticoids. These data demonstrate that A6 cells contain transcriptionally active GR but not MR and thus suggest a molecular basis for the defect in A6 cell SCC response to aldosterone. Our results also demonstrate that GR is capable of mediating hormone stimulation of SCC, a classic mineralocorticoid response. Finally, the observation that heterologous expression of rMR can localize normally to the A6 nucleus in a hormone-dependent fashion and restore both the transcriptional and SCC response to mineralocorticoids suggests that MR function is conserved in species as distantly related as toads and mammals.

Aldosterone↗
PubMed1998

PMA and staurosporine affect expression of the PCK gene in LLC-PK1-F+ cells.

The addition of phorbol 12-myristate 13-acetate (PMA) to renal LLC-PK1-F+ cells caused a rapid decrease in the level of phosphoenolpyruvate carboxykinase (PCK) mRNA and reversed the stimulatory effects of exposure to acidic medium (pH 6.9, 10 mM HCO-3) or cAMP. In contrast, prolonged treatment with PMA increased the levels of PCK mRNA. The two effects correlated with the membrane translocation and downregulation of the alpha-isozyme of protein kinase C and were blocked by pretreatment with specific inhibitors of protein kinase C. The rapid decrease in PCK mRNA caused by PMA occurred with a half-life (t1/2 = 1 h) that is significantly faster than that measured during recovery from acid medium or following inhibition of transcription (t1/2 = 4 h). The effect of PMA was reversed by staurosporine, which apparently acts by inhibiting a signaling pathway other than protein kinase C. Staurosporine had no effect on the half-life of the PCK mRNA, but it stimulated the activity of a chloramphenicol acetyltransferase gene that was driven by the initial 490 base pairs of the PCK promoter and transiently transfected into LLC-PK1-F+ cells. This effect was additive to that of cAMP, and neither stimulation was reversed by PMA. The stimulatory effect of staurosporine was mapped to the cAMP response element (CRE-1) and P3(II) element of the PCK promoter. The data indicate that, in LLC-PK1-F+ cells, activation of protein kinase C decreases the stability of the PCK mRNA, whereas transcription of the PCK gene may be suppressed by a kinase that is inhibited by staurosporine.

Animals↗
PubMed1998

Regulation of vascular endothelial growth factor receptor KDR in vitro by a soluble factor in confluent endothelial cells.

Hypoxia regulates the expression of both vascular endothelial growth factor (VEGF) and its receptor (KDR). We have shown that cell density regulates VEGF expression in colon cancer and hypothesized that a similar mechanism regulates KDR in endothelial cells. Human umbilical vein endothelial cells were grown as sparse and confluent monolayers. Northern blot analysis revealed that KDR and VEGF mRNA expression in confluent cells was more than two-fold greater than in sparse cells. In contrast, flt-1 expression increased only slightly in cells grown to confluence. Cells were then plated at various concentrations and subjected to semi-quantitative PCR; KDR mRNA expression increased as cell density increased. Serum-free conditioned medium from cells grown to confluency for 48 h was added to sparsely plated cells, and KDR expression in the sparse cells increased twofold. We conclude that cell density regulates KDR endothelial cell expression via an unidentified soluble factor.

Blotting, Northern↗
PubMed1998

Effect of renin gene transfer on blood pressure in the spontaneously hypertensive rat.

To investigate whether molecular variation in the renin gene contributes to the greater blood pressure of spontaneously hypertensive rats (SHR) versus normotensive Brown Norway (BN) rats, we measured blood pressure in an SHR progenitor strain and an SHR congenic strain that are genetically identical except at the renin gene and an associated segment of chromosome 13 transferred from the BN strain. Backcross breeding and molecular selection at the renin locus were used to create the SHR congenic strain (designated SHR.BN-Ren) that carries the renin gene transferred from the normotensive BN strain. We found that transfer of the renin gene from the BN strain onto the genetic background of the SHR did not decrease blood pressure in rats fed either a normal or high-salt diet. In fact, the systolic blood pressures of the SHR congenic rats tended to be slightly greater than the systolic blood pressures of the SHR progenitor rats. However, the congenic strain exhibited lower serum high-density lipoprotein cholesterol, and greater levels of total cholesterol, very-low-density lipoprotein, and intermediate-density lipoprotein cholesterol during administration of a high-fat, high-cholesterol diet. These findings demonstrate that (1) under the environmental circumstances of the current study, the greater blood pressure of SHR versus BN rats cannot be explained by strain differences in the renin gene and (2) a quantitative trait locus affecting lipid metabolism exists on chromosome 13 within the transferred chromosome segment. The SHR.BN-Ren congenic strain may provide a useful new animal model for studying the interaction between high blood pressure and dyslipidemia in cardiovascular disease.

Animals↗
PubMed1998

Evidence of potential regulation by interleukin-4 of the soluble intercellular adhesion molecule 1 level in patients with seasonal allergic rhinitis under provocation by a small amount of natural allergen.

Interleukin-4 (IL-4) and intercellular adhesion molecule 1 (ICAM-1) are assumed to be involved in the pathogenesis of allergic disease. In this study, we examined the potential link between IL-4 and soluble ICAM-1 (sICAM-1) levels in patients with allergic rhinitis. The levels of sICAM-1 and IL-4 in sera and in nasal epithelial lining fluids (ELF) from 12 patients with Japanese cedar pollinosis were measured preseason through postseason, and the results were compared with those from 7 healthy subjects. In sera from the allergic subjects, the levels of sICAM- 1 were upregulated during the early part of the season and downregulated during the middle of the season, with upregulation of the IL-4 levels. Moreover, a negative correlation was found between the serum sICAM-1 levels and serum IL-4 levels during the middle (r = -.80) and late (r = -.73) parts of the season. In ELF from allergic subjects, the levels of sICAM-1 were significantly upregulated during the early and middle parts of the season, and began to be downregulated during the late part of the season, with upregulation of the levels of IL-4. In conclusion, IL-4 possibly acts as a potential suppressor of sICAM-1 in the pathogenesis of seasonal allergic rhinitis, at least under provocation by a small amount of natural allergen.

Adult↗
PubMed1998

Role of FGF3 in otic capsule chondrogenesis in vitro: an antisense oligonucleotide approach.

Initiation of otic capsule chondrogenesis depends on interactions between the otocyst and surrounding periotic mesenchyme. We previously reported localization of endogenous basic fibroblast growth factor (FGF2) to the epithelium of the mouse otocyst, and initiation of chondrogenesis in cultured periotic mesenchyme by this epithelial-derived signaling molecule. We now report that FGF3, related to FGF2, can also initiate otic capsule chondrogenesis. We show localization of endogenous FGF3 to the otocyst, and suppression of chondrogenesis by antisense oligonucleotides complementary to different regions of the murine FGF3 gene. Our results support a role for FGF3 in otic capsule formation in situ.

Animals↗
PubMed1998

The herbal medicine sho-saiko-to inhibits the growth of malignant melanoma cells by upregulating Fas-mediated apoptosis and arresting cell cycle through downregulation of cyclin dependent kinases.

The anti-tumor effect and its mechanism of the herbal medicine sho-saiko-to were investigated on a murine malignant melanoma cell line (Mel-ret). Sho-saiko-to induced apoptotic cell death of Mel-ret cells with a definite increase of cell surface Fas antigen and Fas ligand (FasL). Sho-saiko-to arrested Mel-ret cells in G1 phase by decreasing the expression of cyclin-dependent kinase (cdk) 4 and its homologue cdk6. Kinase activities of cdk4 and cdk6 were identified to be downregulated by sho-saiko-to. Ingredient analysis revealed that baicalin is likely the main active constituent in the upregulation of Fas antigen and Fas ligand, while glycyrrhizin is the main constituent in the inhibition of cdks.

Animals↗
PubMed1998

Mutation analysis of the putative tumor suppressor PTEN/MMAC1 in human ovarian cancer.

A putative tumor suppressor, PTEN/MMAC1 gene was recently identified at 10q23 and was found to be frequently altered in several types of human tumors. To determine the possible role of this gene in human ovarian tumors, we screened 31 unselected primary epithelial ovarian cancers with matched normal tissues and 7 ovarian cancer cell lines. Two homozygous deletions (4.8%) were detected in primary ovarian tumors by a semi-quantitative multiplex polymerase chain reaction. However, no point mutations were observed in any of the PTEN/MMAC1 coding sequences as determined by denaturing high-performance liquid chromatography and DNA sequencing. These data indicate that PTEN/MMAC1 mutations are rare in ovarian cancers.

Alternative Splicing↗
PubMed1998

[Regeneration of costal cartilage by pectus excavatum and thoracic cage remodeling].

In order to identify whether the regeneration of costal cartilage is the basis of post-surgical repair of pectus excavatum and thoracic cage remodeling, 151 cases were followed up for 0.25 to 14 years. The main procedures in treatment were 3 steps: To curve the mental strut as a bow, to repair the perichondrium as a tube, and to persist in post-operative therapy. The results showed that regeneration of the costal cartilages appeared 3 months postoperatively in the cases treated by this method. It was concluded that a satisfactory thoracic cage could be remodeled by improving the technique of repairing pectus excavatum and persisting in postoperative therapy according to the regeneration regularity.

Adolescent↗
PubMed1998

Effects of genistein on aggregation and cytosolic free calcium in pig platelets.

AIM: To study the effects of genistein on aggregation and cytosolic free calcium concentration in platelets. METHODS: Using turbidimetry to analyse aggregation and using Fura-2 fluorescence technique to determine Ca2+ level. RESULTS: Genistein strongly inhibited the pig platelet aggregation induced by thrombin (250 U.L-1). When genistein concentrations were 5 and 20 mumol.L-1, the inhibition rates on the aggregation were 52% and 73%, respectively. Genistein inhibited the rise of cytosolic free calcium concentration in platelets stimulated by thrombin (500 U.L-1) in the presence of extracellular Ca2+ 1 mmol.L-1. When genistein concentrations were 10, 20, 40, and 80 mumol.L-1, the inhibition rates were 24%, 40%, 63%, and 65%, respectively, but no effect on thrombin-induced internal Ca2+ release from dense tubular system. CONCLUSION: Genistein is a potential anti-platelet agent, mainly due to an inhibition of Ca2+ influx.

Animals↗
PubMed1998

Effects of acupuncture at fengchi point (GB 20) on cerebral blood flow.

Blood velocity in the vertebral artery and the basilar artery was observed before and after acupuncture at Fengchi point (GB 20) in 97 patients by transcranial Doppler ultrasonic detecting. The results showed that the blood velocity in patients with either high or low blood flow had significant changes after acupuncture (P < 0.001).

Acupuncture Points↗
PubMed1998

[Effects of mifepristone on ICE expression and Fas expression in early pregnant chorionic villi].

This study addressed the question whether mifepristone has any effect on apoptosis in early pregnant chorionic villi. Interleukin 1 beta converting enzyme(ICE) expression and Fas expression in early pregnant villi and their changes following mifepristone administration were detected by immunohistochmical method and computer image analysis. During early pregnancy, ICE and Fas were expressed in all component chorionic cells, predominantly syncytiotrophoblasts. ICE stained cytoplasma. Fas stained mainly cytoplasma, and in partial trophoblastic cells, Fas was expressed on membrane and nucleus. In the villi from the pregnant women who received mifepristone for 2 days, expression of Fas increased markely; the ratio of positive nuclear staining cells were significantly raised, but the immunostaining intensity of ICE was slightly increased. These results suggest that mifepristone may terminate early pregnancy via increasing the expression of Fas and promoting apoptosis in the chorionic villi.

Abortifacient Agents, Steroidal↗
PubMed1998

[Relationship between change of erythrocyte membrane lipid composition and pregnancy induced hypertension].

OBJECTIVE: To study the cause of decreased erythrocyte deformability and its relation to pregnancy induced hypertension (PIH). METHODS: The cholesterol and phospholipid content of erythrocyte membrane in 24 non-pregnant healthy women, 22 normotensive pregnant women and 36 cases with PIH were determined using automatic biochemical analysor, Gas chromatography and modified colorimetric method. RESULTS: The cholesterol content and the cholesterol/phospholipid (C/P) ratio of the erythrocyte membrane were obviously higher in the group with moderate or severe PIH than that in the nonmotensive pregnancies (P < 0.01). There was no significant difference between mild PIH group and the normotensive pregnant group (P > 0.05). CONCLUSION: The increase of cholesterol content and C/P ratio in the erythrocyte membrane might be involved in the pathophysiology of PIH. The alteration of cholesterol content in the erythrocyte membrane probaby reflected the disturbance of serum lipid metabolism.

Adult↗
PubMed1998

[The structure and mRNA expression of p16 gene in AML cells].

OBJECTIVE: To explore the role of p16 gene in the pathogenesis of AML. METHODS: PCR-SSCP and Northern blot were used to analyse the structure and mRNA expression of p16 gene in 16 cases of AML. RESULTS: No deletion or mutation of p16 gene were found in all of the 16 cases. The p16 mRNA expression in 12 AML at diagnosis or relapse was significantly lower than that in 4 long term remission cases and normal controls. p16 mRNA expression was significantly higher in a case of AML with p53 mutation. CONCLUSION: p16 gene may not play an important role in the pathogenesis of AML. The high p16 expression in the patient with p53 mutation might reflect a kind of inbalance of the feedback cycle.

Adolescent↗
PubMed1998

[The expression of proliferating cell nuclear antigen and alpha smooth muscle actin in papillary muscles of the patient with rheumatic heart disease and its significance].

OBJECTIVES: To reveal the change of chronic rheumatic cardiomyocyt phenotype and its relationship with myocardium fibrosis. METHODS: The papillary muscles samples were obtained from patients with rheumatic heart disease during mitral valve replacement. Normal papillary muscles samples obtained from adult and fetal heart during autopsy in control group. The specimens were examined using immunohistochemistry and immunoelectron microscopy observation with monoclonal antibody of antiproliferating cell nuclear antigen (PCNA) and anti-alpha smooth muscles actin (alpha-SMA), and imaging analysis was performed. RESULTS: The interstitial fibrosis (24.7% +/- 3.05%) and the ratio between inner and outer diamater of arteriolas (0.405 +/- 0.035) in rheumatic myocardium were higher significantly than those in normal myocardium. Immunohistochemical PCNA expression was not only in interstitial but also in hypertrophic cardiomyocytes of rheumatic heart disease. The positive expression in rheumatic myocardium increased. There were a lot of rough endoplasmic reticula, ribosomes and Golgi bodies in cytoplasm of PCNA and alpha-SMA positive cells. The degree of PCNA and alpha-SMA positive expression was increased with enlargement of fibrosis areas. CONCLUSIONS: There is not only a high expression of PCNA and alpha-SMA in the myocardium of patients with rheumatic heart disease but also in fetal myocardium. We suggested that pathological myocardial cells are constructive phenotype and synthetive phenotype. PCNA and alpha-SMA positive expression cells are in the proliferating stage, they take part in fibrotic progress and vascular reconstruction in the myocardium.

Adult↗
PubMed1998

[The carcinogenetic and tumor-promoting effects of concentrated Helicobacter pylori culture supernatant in rats].

OBJECTIVE: To investigate the carcinogenetic and tumor-promoting effect of concentrated Helicobacter pylori culture supernatant (CHCS). METHODS: 0.25% and 0.5% CHCS in drinking water administered orally for 52 weeks in rats, the changes of mucosal thickness, adherent mucosal mucus amount, DNA synthesis rate and precancerous lesions incidence in different times were examined, and the promoting effect of CHCS used in different periods on experimental carcinogenesis induced by MNNG was also clarified. RESULTS: Decreased mucosal thickness and amount of mucosal adherent mucus, increased DNA synthesis were found after CHCS feeding for 5 weeks in a dose- and time-dependent manner. By the end of the experiment at the 52nd week, the incidence of intestinal metaplasia(IM), sulfomucin positive IM and dysplasia in 0.5% CHCS group(57%, 39%, 18% respectively) were significantly higher than those in 0.25% CHCS group(28%, 10%, 3% respectively) and control group(7%, 0%, 0% respectively). Whenever CHCS was used prior to, together with, or following MNNG administration, the incidences of gastric cancer and precancerous lesions were significantly increased in comparison with those in the rats treated with MNNG alone. CONCLUSION: Hp cytotoxin(s) may have direct carcinogenetic and tumor-promoting effects.

Animals↗
PubMed1998

Effect of splenectomy on CCl4-induced liver fibrosis in rats.

OBJECTIVE: To assess the effects of splenectomy on CCl4-induced liver fibrosis in rats. METHODS: Wistar rats were injected with CCl4 subcutaneously for 3 to 15 weeks to develop liver fibrosis. Two hundred and thirty-six rats were divided into 9 groups: (1) model group without splenectomy; (2) splenectomized group in which operation was performed before induction of fibrosis; (3) sham-operated group in which caparotomy was done before induction of fibrosis; (4) (5) (6) groups in which splenectomy was performed at the 6th, 9th and 12th week after induction of fibrosis, respectively; and (7) (8) (9) sham operation was also performed at the 6th, 9th and 12th week after induction of fibrosis, respectively. The spleen and liver biopsy, hepatic hydroxyproline, liver homogenate levels of procollagen type III (PC III), hyaluronic acid (HA), laminin (LN) and volume density of collagen were examined at different times. RESULTS: The results showed that the degree of hepatic damage and liver fibrosis in splenectomized group was significantly milder than that in model group and sham-operated groups. Splenectomy might delay the progress of liver fibrosis for about 3 weeks. The role of preventing rat liver fibrosis was also observed when splenectomy was performed after CCl4 induction of fibrosis for 6 and 9 weeks. CONCLUSIONS: These results suggest that splenectomy may be of a preventive role against CCl4-induced rat liver fibrosis to a certain degree.

Animals↗