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Biomedical subjects

P Liu

Publications and source records attributed to P Liu.

At least 163 records · Page 9Linked to original sources
PubMed1999

[Abnormal expression of several oncogenes during hepatocarcinogenesis in WHV/myc transgenic mice].

OBJECTIVE: To explore at cellular level the abnormal expression of related oncogenes during hepatocarcinogenesis in the WHV/myc transgenic mice. METHODS: With specific molecular probes, in situ hybridization was used to detect the expression of c-myc transgene,IGF-II gene as well as c-jun, c-fos, and c-H-ras oncogenes in the liver sections from WHV/myc transgenic mice in different stages of the carcinogenic process. RESULTS: The overexpression of c-myc transgene and IGF-II gene transcripts were detected in liver sections from the earlier neonatal transgenic mice. Then, the expression levels of these two genes were rapidly decreased and undetectable. At the time of the liver tumor development, the expression of c-myc transgene and IGF-II gene resumed. The c-jun, c-fos and c-H-ras genes expressed more intensely in the livers from preneoplastic WHV/myc mice than from normal mice. CONCLUSION: The overexpressions of c-myc transgene and IGF-II gene in the earlier neonatal stage and tumoral stage may be of importance for the development and maintenance of a transformed phenotype. During the prenoplastic "silent" period of c-myc transgene expression in WHV/myc transgenic mice, several oncogenes are overexpressed in the livers.

Animals↗
PubMed1999

MTA (LY231514) in combination treatment regimens using human tumor xenografts and the EMT-6 murine mammary carcinoma.

An important component in the development of a new anticancer drug is an understanding of its potential for inclusion in combination treatment regimens. LY231514, a multitargeted antifolate (MTA), was tested in combination with cisplatin, methotrexate, 5-fluorouracil, paclitaxel, docetaxel, doxorubicin, LY329201 (a glycinamide ribonucleotide formyltransferase [GARFT] inhibitor), and fractionated radiation therapy in vivo using EMT-6 mammary carcinoma, human HCT 116 colon carcinoma, and human H460 nonsmall cell lung carcinoma grown as xenografts in nude mice. Isobologram methodology was used to determine the additivity or synergy of the combination regimens. MTA administered with cisplatin, paclitaxel, docetaxel, or fractionated radiation therapy produced additive to greater than additive tumor response by tumor cell survival assay and tumor growth delay. While an additive tumor response was observed when MTA was administered with methotrexate, synergistic tumor responses were seen when MTA was administered with the GARFT inhibitor, LY329201, or with the topoisomerase I inhibitor, irinotecan. MTA was administered in combination with full doses of each anticancer agent studied, with no evidence of increased toxicity resulting from the combination.

Animals↗
PubMed1999

[Study on the relationship between perinatal hypoxia and concentration of endothelin-1 in amniotic fluid].

OBJECTIVE: To investigate the relationship between endothelin-1 (ET-1) concentration in amniotic fluid (AF) and perinatal hypoxia. METHODS: 161 cases were measured for amniotic fluid(AF) ET-1 levels by radioimmunoassay. 110 cases of normal pregnancy were included in control group among which 30 term pregnancies were simultaneously measured for maternal and umbilical plasma ET-1. 51 cases of intrauterine hypoxia were the study group. RESULTS: (1) The AF ET-1 levels showed increasing trend after 14 weeks (P < 0.01). (2) Fetal plasma ET-1 levels were significantly higher than that of maternal plasma ET-1 levels, but lower than those of AF ET-1 (P < 0.01). The ET-1 levels of umbilical plasma had positive correlation with those of AF ET-1 (r = 0.952, P < 0.01), but there is no correlation with levels of maternal plasma ET-1 (r = 0.338, P < 0.05). (3) In study group, the level of AF ET-1 was elevated with severity of hypoxia, the average level of AF ET-1 in cases of intrauterine hypoxia was (30.654 +/- 5.832) ng/L. In cases of severe neonatal asphyxia it was (960.650 +/- 236.698) ng/L. CONCLUSIONS: The ET-1 exists in AF and gradually increases while pregnancy advanced. AF ET-1 levels can be served as a marker to predict perinatal hypoxia.

Adult↗
PubMed1999

[Changes of osteopontin and matrix Gla protein mRNA expressions in the healing process of rat thoracic aorta damaged by balloon angioplasty].

Using Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR) the dynamic changes of osteopontin (OPN) and matrix Gla protein (MGP) mRNA expression in the healing process of rat thoracic aorta damaged by balloon angioplasty were investigated. The results showed that expression of OPN and MGP in the thoracic aorta damaged group was higher compared with normal group. 1, 7, and 14 d after thoracic aorta was damaged, expression of OPN and MGP was increased gradually, and decreased after artery damaged 21 d.

1-Carboxyglutamic Acid↗
PubMed1999

Relationship between serum antisperm antibodies and anticardiolipin antibodies and clinical pregnancy outcome in an in vitro fertilization and embryo transfer program.

OBJECTIVE: To study the influence of maternal immunological factors on clinical pregnancy outcome in an in vitro fertilization and embryo transfer (IVF-ET) program. METHODS: One hundred and fifty IVF-ET treatment cycles from November 1995 to November 1996 were studied. The indication for IVF-ET treatment was bilateral blocked tubes. Serum antisperm antibodies and anticardiolipin antibodies were measured using enzyme-linked immunosorbent assay (ELISA). Cleavage rate and successful pregnancy rate in relation to antibody status of infertile women after IVF-ET treatment were assessed. RESULTS: Lower cleavage rate (64.2% +/- 32.1%) was found in 44 cycles of antisperm antibody seropositive women, compared with 84.8% +/- 18.7% in 106 cycles of seronegative women (P < 0.05). The clinical pregnancy rate was 31.8% in antisperm antibody-positive cycles and 20.8% in negative cycles (P > 0.05). The abortion rates of the two groups were similar (P > 0.05). Lower pregnancy rate (9.5%) was found in 21 cycles of serum anticardiolipin antibody-positive group, compared with 26.3% in 129 cycles of seronegative women (P < 0.05). Of patients with bio-chemical pregnancy and no pregnancy, 20.0% and 16.2%, respectively, had seropositive anticardiolipin antibody, compared with 5.6% of patients with clinical pregnancy (P < 0.05). CONCLUSION: Serum immunological factors may play a part in clinical pregnancy outcome in IVF-ET.

Adult↗
PubMed1999

Relationship between diabetes mellitus, impaired glucose tolerance and age, menopause, pregnancy: a survey of 5153 women in Shenzhen.

OBJECTIVE: To investigate the relationship between diabetes mellitus (DM) including impaired glucose tolerance (IGT) and the factors of age, menopause, and pregnancy. METHODS: A systemic epidemiological survey was conducted in 5153 women, aged 20 years and above. RESULTS: The prevalence of DM was 4.58%, and IGT 12.83%. In those subjects with DM less than 59 years old and those with IGT less than the age of 49, the prevalence was parallel to the increase of age. Ten years might lead the IGT subjects into DM. Moreover, the prevalence of DM and IGT after menopause were significantly high. It was found that the prevalence of DM and IGT in mothers who had conceived giant baby was significantly higher than that of the others. CONCLUSIONS: Therapeutic emphasis should be laid on the population of women in the age between 50 and 59, while the management of IGT women is equally important. The early intervention of IGT subjects in the age between 40 and 49 is essential in decreasing the prevalence of DM. Disorders of the endocrine system during climacteric might play an important role in the development of DM and IGT. Moreover, the mothers who have conceived giant babies are at great risk for DM, and thus, this population should be closely monitored.

Adult↗
PubMed1999

[Serapharmacological effect of fuzheng huayu 319 Decoction on expression of type I collagen and transforming growth factor beta 1 in hepatic stellate cells].

OBJECTIVE: To investigate the main serapharmacological mechanism of antifibrotic action of Fuzheng Huayu 319 Decoction (FHD) at cellular and molecular level. METHODS: Hepatic stellate cells (HSC) were isolated from the normal rats and subcultured. Normal rats were medicated with FHD and their blood serum collected to prepare the medicated serum, which was incubated with the subcultured HSC. Then, the extra- and intracellular collagen synthetic rates were assayed with collagenase digestion method, type I collagen content in the medium measured with ELISA, transforming growth factor beta 1 (TGF beta 1) protein production semiquantified by immunocytochemistry stain and image analysis system, the gene expressions of type I procollagen and TGF beta 1 analyzed by RT-PCR. RESULTS: FHD medicated serum could obviously inhibit the extra- and intracellular collagen synthetic rates, decreased type I procollagen mRNA expression and its secretion, downregulate TGF beta 1 mRNA and its protein expression. CONCLUSION: FHD could inhibit HSC activation markedly, the main mechanism of its antifibrotic action may be the medicated serum inhibition on type I procollagen and TGF beta 1 gene expression.

Animals↗
PubMed1999

[Influence of triiodothyronine and insulin on liver adenine nucleotide levels in portal triad-clamping rats].

OBJECTIVE: To assess the influence of triiodothyronine(T3) and insulin on liver adenine nucleotide levels in portal triad-clamping rats. METHOD: A rat model of normothermic portal triad clamping was established to observe the influence of T3 and insulin on the contents of liver adenine nucleotides and survival rates. RESULT: The ATP levels and the 72 h-survival rate of T3 group were significantly higher than those of insulin group and saline group(P < 0.05). The blood glucose levels were obviously decreased and all the rats died within 6 hours postoperation in insulin group. CONCLUSIONS: T3 can improve hepatic energy metabolism after portal triad clamping and increase survival rate, whereas such effects were not found in insulin group.

Adenine Nucleotides↗
PubMed1999

[Determination of sarafloxacin by high performance liquid chromatography (HPLC)].

A method for the separation and determination of Sarafloxacin by HPLC was developed. The sample was dissolved in a mixture of V(acetonitrile):V(water) = 1:1. Operating conditions were as follows: mu-Bondapak C18 column (3.9 mm x 300 mm), V(acetonitrile):V(methanol):V(2 mmol/L H3PO4, adjust pH 3.5 with triethylamine) = 30:5:65 as mobile phase with a flow rate of 1 mL/min, UV detection at 278 nm, and column temperature was 15 degrees C. Under the above conditions, Sarafloxacin and other impurities were separated from each other. The method was simple, rapid, sensitive and accurate.

Anti-Infective Agents↗
PubMed1998

Early effects of pp60(v-src) kinase activation on caveolae.

Members of the nonreceptor tyrosine kinase family appear to be targeted to caveolae membrane. We have used a Rat-1 cell expressing a temperature sensitive pp60(v-src) kinase to assess the initial changes that take place in caveolae after kinase activation. Within 24-48 h after cells were shifted to the permissive temperature, a set of caveolae-specific proteins became phosphorylated on tyrosine. During this period there was a decline in the caveolae marker protein, caveolin-1, a loss of invaginated caveolae, and a 70% decline in the sphingomyelin content of the cell. One of the phosphorylated proteins was caveolin-1 but it was associated in coimmunoprecipitation assays with both a 30 kDa and a 27 kDa tyrosine-phosphorylated protein. Finally, the cells changed from having a typical fibroblast morphology to a rounded shape lacking polarity. In light of the recent evidence that diverse signaling events originate from caveolae, pp60(v-src) kinase appears to cause global changes to this membrane domain that might directly contribute to the transformed phenotype.

Animals↗
PubMed1998

Regulation of arachidonic acid release and prostaglandin E2 production in thymic epithelial cells by ATPgammaS and transforming growth factor-alpha.

The arachidonic acid metabolites produced by thymic epithelial cells play a pivotal role in thymocyte development. We have discovered that ATP and TGF-alpha regulate the arachidonic acid metabolism in TEA3A1 rat thymic epithelial cells by activating phospholipase A2 enzymatic activity. Our present study demonstrates that ATP and its nonhydrolyzable analog ATPgammaS stimulate both prostaglandin E2 production and Ca2+ influx in TEA3A1 cells. The stimulation of prostaglandin E2 production and Ca2+ influx by ATP is inhibited by pertussis toxin treatment, indicating that ATP mediates its effect by binding to a G-protein-coupled purinergic receptor. Treatment of cells with ATPgammaS and transforming growth factor-alpha results in a synergistic activation of phospholipase A2 and stimulation of prostaglandin E2 production. Results from experiments using an inhibitor of receptor-mediated Ca2+ influx indicate that the synergistic stimulation of prostaglandin E2 production by ATPgammaS and transforming growth factor-alpha requires ATPgammaS-mediated Ca2+ influx. The inhibitor of tyrosine kinase genistein also blocked both ATPgammaS- and ATPgammaS plus transforming growth factor-alpha-mediated stimulation of prostaglandin E2 production, indicating that the activation of phospholipase A2 may involve a protein tyrosine phosphorylation step.

Adenosine Triphosphate↗
PubMed1998

Intracellular calcium signalling in rat parotid acinar cells that lack secretory vesicles.

Secretory vesicles from pancreatic acinar cells have recently been shown to release Ca2+ after stimulation with Ins(1,4,5)P3 [Gerasimenko, Gerasimenko, Belan and Petersen, (1996) Cell 84, 473-480]. These observations have been used in support of the hypothesis that Ca2+ release from secretory vesicles could be an important component of stimulus secretion coupling in exocrine acinar cells. In the rat, ligation of the parotid duct causes a reversible atrophy of the parotid gland. Most notably, after atrophy the acinar cells are reduced in size and no longer contain secretory vesicles [Liu, Smith, and Scott (1996) J. Dent. Res. 74, 900]. We have measured cytosolic free-Ca2+ concentration ([Ca2+]i) in single, acutely isolated, rat parotid acinar cells, and compared Ca2+ mobilization in response to acetylcholine (ACh) stimulation in cells obtained from control animals to that in cells lacking secretory vesicles obtained after atrophy of the parotid gland. Application of 50-5000 nM ACh to control cells gave rise to a typical, dose-dependent, biphasic increase in [Ca2+]i, of which the later, plateau, phase was acutely dependent on the extracellular Ca2+ concentration. An identical pattern of response was observed with cells obtained from atrophic glands. Low concentrations of ACh (10-100 nM) occasionally produced [Ca2+]i oscillations of a similar pattern in cells from both control and atrophic glands. We were able to show that Ca2+ rises first in the apical pole of the cell and the increase then spreads to the rest of the cell in cells from control glands but not in cells from atrophic glands. However, at present we are unable to determine whether this is due to the lack of secretory vesicles or whether the separation is too small to measure in the smaller acinar cells obtained from atrophic glands. We conclude therefore, that secretory vesicles make no significant contribution to overall Ca2+ mobilization in rat parotid acinar cells, nor are they required for oscillatory changes in [Ca2+]i to occur. However we are unable to eliminate completely any role for secretory vesicles in initiating Ca2+ mobilization at the apical pole of the cell.

Acetylcholine↗
PubMed1998

Lesions of perirhinal cortex produce spatial memory deficits in the radial maze.

Rats with bilateral electrolytic lesions of perirhinal cortex (PRC) or sham control (SHAM) lesions were tested in spatial reference and working memory tasks in the radial arm maze. In experiment 1, one arm of the maze was baited and always located in a fixed position relative to the extra-maze environment. PRC lesioned animals made a significantly greater number of errors than did SHAM animals during initial training in this reference memory task and exhibited a delay-dependent impairment on trial 5 in a series when a delay period of 5, 60, 120, or 240 s was inserted between trials 4 and 5. In experiment 2, when a second group of the animals was tested on the standard radial arm maze working memory task, the performance of the PRC group was markedly impaired relative to controls. These data demonstrate that electrolytic PRC lesions result in a deficit in both spatial reference and spatial working memory tasks. These effects are interpreted as being consistent with the idea that PRC plays an important role in episodic memory processes. These processes may include the storage of information, which is required for the performance of spatial tasks.

Animals↗
PubMed1998

Increased liver uptake of liposomes and improved targeting efficacy by labeling with asialofetuin in rodents.

To improve liposome-directed therapy of liver disease and gene delivery, it would be beneficial to selectively target hepatocytes. For this purpose, conventional liposomes (CL) were labeled with asialofetuin (AF), an asialoglycoprotein. The biodistribution of AF-labeled liposomes (AF-L) in mice and their incorporation into rat hepatocytes, and their potential use in acute liver injury, were investigated. AF-L displayed a quicker plasma clearance than CL, and 25.4%, 2.7%, and 1.2% of the injected dose remained in the plasma versus 47.0%, 26.1%, and 9.5% of CL, respectively at 2, 4, and 20 hours after the injection. Total liver uptake of AF-L (73%+/-3.9%) was markedly higher (P < .005) than CL (16.5%+/-1.8%) 4 hours after the injection. Liposomal radioactivity (cpm/mg) was greatly enhanced in the liver (11-fold) during the first 4 hours after the administration of 14C-AF-L, and was much higher than in 14C-CL-injected mice (1.5-fold). In vitro incubation of isolated rat hepatocytes with 14C-AF-L or intravenous injection of 14C-AF-L in rats resulted in higher hepatocyte-bound radioactivity compared with 14C-CL (P < .01-.005). AF-L-associated 1,1'-dilinoleyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) fluorescent signals were not only located in Kupffer cells, but also in hepatocytes, in which bile canaliculus networks were imaged. Intravenous administration of vitamin E (VE)-associated CL (VE-CL, 1 mg/mouse) significantly lowered alanine transaminase (ALT) levels in CCl4-treated mice (196+/-79 vs. 2,107+/-235 U/mL; P < .01). The ALT level in CCl4 + VE-AF-L group was decreased to 38+/-16 units/mL, which was significantly lower than the CC14 + VE-CL group (P < .05). In conclusion, labeling liposomes with AF led to a shortened liposome plasma half-life and greatly enhanced uptake of AF-L liposome by the liver. The enhanced uptake resulted from an increased incorporation of hepatocytes with AF-L liposomes. VE-associated AF liposomes further improved the protective effect of VE liposomes on CC14-induced acute liver injury in mice. Preferential hepatocyte incorporation of AF-L liposomes suggests a useful hepatocyte-targeting approach for drug delivery and gene transfection.

Alanine Transaminase↗
PubMed1998

Endovascular stents in arterial injury after radiotherapy.

We evaluated preliminary success and patency of stenting for the treatment of radiation-induced arterial diseases. Thirteen stents were placed in 8 patients to treat occlusion (n = 3), aneurysm (n = 1), residual stenosis (n = 2), multiple stenoses (n = 1), and delayed restenosis after previous balloon angioplasty (n = 1). Interventional procedure was successfully performed in 8 patients for their arterial lesions after radiotherapy. Six patients underwent interventional procedure once or twice. Two patients underwent PTA 4 times. Five of these patients demonstrated primary patency with relief of clinical symptoms with a mean follow-up of 2 years (range: 8-60 months). Clinical improvement was noted in the other patients. Our results suggest that stent placement by single or multiple techniques may have immediate effect on arterial lesions caused by radiation and can be considered as a therapeutic option of choice in these cases.

Adult↗
PubMed1998

Detection of breast cancer with conventional mammography and contrast-enhanced MR imaging.

The aim of this study was to compare the diagnostic performance of conventional mammography and dynamic contrast-enhanced fast 3D gradient-echo (GRE) MRI regarding the detection and characterization of breast lesions relative to histopathologic analysis and to assess the results of a combined evaluation of both methods. fifty consecutive patients with 63 histopathologically verified breast lesions underwent dynamic contrast-enhanced GRE MRI in addition to routine conventional mammography. All lesions were classified by both methods on a five-point scale as benign or malignant, and the results were correlated to histopathology. Conventional mammography and dynamic MRI yielded a sensitivity and specificity of 82 and 64 %, and 92 and 76 %, respectively. The difference between the results was statistically not significant (p > 0.05) with areas under the receiver-operating-characteristics curves of 0.807 for mammography and 0.906 for MR imaging. Combination of the results of both methods slightly increased the sensitivity for detection of breast cancer to 95 % but decreased specificity to 52 %. In this selected patient subset, including only patients referred for excisional biopsy, contrast-enhanced dynamic MRI proved more sensitive and specific than conventional mammography regarding the detection of malignancy. While a combination of both methods yields a slightly improved sensitivity, specificity is vastly reduced.

Adult↗