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Biomedical subjects

X Liu

Publications and source records attributed to X Liu.

At least 847 records · Page 47Linked to original sources
PubMed1999

Use of Ca2+ modulation to evaluate biliary excretion in sandwich-cultured rat hepatocytes.

Previous work in our laboratory has indicated that biliary excretion of a substrate in sandwich-cultured hepatocytes can be quantitated by measurement of substrate accumulation in the presence and absence of extracellular Ca2+. The present study was designed to examine the effects of Ca2+ on taurocholate accumulation and tight junction integrity in cultured hepatocytes. Kinetic modeling was used to characterize taurocholate disposition in the hepatocyte monolayers in the presence and absence of extracellular Ca2+. The accumulation of taurocholate in freshly isolated hepatocytes, which lack an intact canalicular network, was the same in the presence and absence of extracellular Ca2+. Electron microscopy studies showed that Ca2+ depletion increased the permeability of the tight junctions to ruthenium red, demonstrating that tight junctions were the major diffusional barrier between the canalicular lumen and the extracellular space. Cell morphology and substrate accumulation studies in the monolayers indicated that Ca2+ depletion disrupted the tight junctions in 1 to 2 min. The integrity of the disrupted tight junctions was not re-established completely after reincubation in the presence of Ca2+ for 1 h. The accumulation of taurocholate was described best by a two-compartment model (cytosol and bile) with Michaelis-Menten kinetics for both uptake and biliary excretion. In summary, Ca2+ depletion does not alter hepatocyte transport properties of taurocholate. Ca2+ modulation may be a useful approach to study biliary excretion of substrates in sandwich-cultured hepatocytes.

Animals↗
PubMed1999

Correlation of biliary excretion in sandwich-cultured rat hepatocytes and in vivo in rats.

The relationship between biliary excretion in sandwich-cultured rat hepatocytes and in vivo in rats was examined. The biliary excretion of seven model substrates in 96-h sandwich-cultured rat hepatocytes was determined by differential cumulative uptake of substrate in the monolayers preincubated in standard buffer (intact bile canaliculi) and Ca2+-free buffer (disrupted bile canaliculi). Biliary excretion in vivo was quantitated in bile duct-cannulated rats. The biliary excretion index of model substrates, equivalent to the percentage of retained substrate in the canalicular networks, was consistent with the percentage of the dose excreted in bile from in vivo experiments. The in vitro biliary clearance of inulin, salicylate, methotrexate, [D-pen2,5]enkephalin, and taurocholate, calculated as the ratio of the amount excreted into the bile canalicular networks and the area under the incubation medium concentration-time profile ( approximately 0, approximately 0, 4.1 +/- 1.0, 12.6 +/- 2.2, and 56. 2 +/- 6.0 ml/min/kg, respectively), correlated with their intrinsic in vivo biliary clearance (0.04, 0, 17.3, 34.4, and 116.9 ml/min/kg, respectively; r2 = 0.99). The model compound 264W94 was not excreted in bile either in vivo or in vitro. The glucuronide conjugate of 2169W94, the O-demethylated metabolite of 264W94, was excreted into bile in vitro when 2169W94, but not 264W94, was incubated with the monolayers; 2169W94 glucuronide undergoes extensive biliary excretion after administration of 264W94 or 2169W94 in vivo. Biliary excretion in long-term sandwich-cultured rat hepatocytes correlates with in vivo biliary excretion. The study of biliary excretion of metabolites in the hepatocyte monolayers requires consideration of the status of metabolic activities.

Animals↗
PubMed1999

Alterations in protein kinase A and protein kinase C levels in heart failure due to genetic cardiomyopathy.

BACKGROUND: It is becoming evident that both cardiac and skeletal muscles are affected in congestive heart failure. Although protein kinases are known to regulate cardiac function, very little is known about their status in cardiac and skeletal muscles during the development of congestive heart failure. OBJECTIVE: To determine changes in the activities and protein levels of protein kinase A (PKA) and protein kinase C (PKC) in cardiac and skeletal muscles in congestive heart failure due to genetic cardiomyopathy on the basis that PKA and PKC are crucial for protein phosphorylation. ANIMALS AND METHODS: Genetically cardiomyopathic UM-X7.1 hamsters (250 to 300 days old) and age-matched Syrian hamsters were used in this study. PKA and PKC activities were assayed by measuring 32P from [gamma-32P]ATP incorporated into synthetic substrates. Relative protein contents of these protein kinases were obtained by using immunoblot analysis in control and failing hamster hearts and skeletal muscles. RESULTS: PKC activity was significantly increased in the failing hearts compared with control preparations. The relative protein contents of cytosolic PKC-alpha and -epsilon , and of particulate PKC-epsilon isozymes were significantly increased in failing hearts. PKC activity was also markedly increased in cardiomyopathic skeletal muscle. Furthermore, PKA activity and protein level in both cardiac and skeletal muscles were significantly increased in the failing heart group compared with control values. CONCLUSIONS: Increased PKC activity in heart failure may be due to changes in PKC-alpha and -epsilon isozymes in cardiomyopathic hearts. Alterations of PKA and PKC in congestive heart failure were not limited to the heart because similar changes in enzyme activities were evident in skeletal muscle.

Animals↗
PubMed1999

Effect of basic fibroblast growth factor on focal ischemic injury and antioxidant enzyme activities.

AIM: To explore the effect of basic fibroblast growth factor (bFGF) on focal cerebral ischemic injury and antioxidant enzyme activities. METHODS: Rats underwent 24-h middle cerebral artery occlusion by intraluminal suture. Infarction volume was shown with staining and quantitated by image analysis system. Neurologic deficit scores were determined with a 0-5 grade scale. Antioxidant enzyme activities of forebrains were detected. RESULTS: bFGF (45 micrograms.kg-1.h-1 i.v. for 3 h, started 5 min after the onset of ischemia) showed potent neuroprotective effects. Infarction volumes were decreased from 272 mm3 +/- 22 mm3 (saline-treated) to 201 mm3 +/- 30 mm3 (bFGF-treated). Neurologic deficit scores were decreased from 3.6 +/- 1.5 (saline-treated) to 2.3 +/- 1.6 (bFGF-treated). Focal cerebral ischemia induced an increase in the activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), but a decrease in the level of glutathione s-transferase (GSH-ST). Treatment of bFGF further increased the CAT activity but had no effect on the activities of SOD, GSH-PX, and GSH-ST. CONCLUSION: bFGF has a neuroprotective effect against focal cerebral ischemic injury. The elevation of CAT activity by bFGF may be involved in this effect.

Animals↗
PubMed1999

Role of nitric oxide synthase and cyclooxygenase in pulmonary vascular control in isolated perfused lungs of ferrets, rats and rabbits.

Dilator products of nitric oxide synthase (NOS) and cyclooxygenase (COX) may contribute to the low normal pulmonary artery pressure (Ppa). In isolated perfused lungs of ferrets, rabbits and rats we investigated this hypothesis by blockade of NOS with L-NAME (L-nitro-arginine methyl ester) and COX with meclofenamate. There were species differences. Inhibition of either enzyme caused little rise in Ppa in ferrets and rats but inhibition of both enzymes caused huge increases in Ppa. We suggest this might be due to intracellular connections between the excitatory pathways for NOS and COX dilators, such that inhibition of one enzyme leads to activation of the other. Impairment of these endothelial-based enzymes in pulmonary vascular disease might lead to severe pulmonary hypertension. By contrast, in rabbits, comparable doses of L-NAME lead to large rises in Ppa which were reversed rather than amplified by COX blockade. NO seems to protect against some pressor/oedema forming product of COX in this species.

Animals↗
PubMed1999

Immunotherapy of bladder cancer targeting P53.

PURPOSE: Superficial bladder cancer is often responsive to immunotherapy with bacillus Calmette-Guerin (BCG). However, some tumors progress despite BCG treatment, and most of these have mutations in the p53 tumor suppressor gene resulting in its over-expression. Overexpressed p53 is therefore a potential target for immunotherapy. The objective of this study was to demonstrate whether human bladder cancer xenografts in SCID mice could be eliminated by cytotoxic T cells (CTL) which recognize over-expressed p53. MATERIALS AND METHODS: Murine CTL which are specific for human p53 were previously generated in our laboratory by peptide immunization of HLA A2.1 transgenic mice. These CTL recognize and lyse human tumor cell lines which over-express p53 in the context of HLA A2.1. The p53 over-expressing HLA A2.1+ human bladder cancer cell line J82 was used to establish subcutaneous or intravesicular tumors in SCID mice. The mice were then administered tail vein injections of 5 x 10(7) p53-specific CTL, control CTL, or phosphate buffered saline (PBS). RESULTS: The subcutaneous tumor mean volume at 5 weeks for the p53-specific CTL treatment group was significantly lower than for both the control CTL or the PBS group (32 mm.3 versus 185 mm.3, p = 0.04 and 32 mm.3 versus 418 mm.3, p = 0.0001). In the mice with intravesicular tumors, a reduction to nonpalpable tumor size in vivo was seen with specific CTL therapy (14% palpable) versus control CTL treatment (86% palpable), the final tumor volume at necropsy was 127 mm.3 versus 246 mm.3 (N.S.). CONCLUSION: The overall response of the human bladder tumors in the SCID mouse model suggests the possibility of targeting p53 in patients with bladder cancer.

Animals↗
PubMed1999

Automation and integration of components for generalized semantic markup of electronic medical texts.

Our group has built an information retrieval system based on a complex semantic markup of medical textbooks. We describe the construction of a set of web-based knowledge-acquisition tools that expedites the collection and maintenance of the concepts required for text markup and the search interface required for information retrieval from the marked text. In the text markup system, domain experts (DEs) identify sections of text that contain one or more elements from a finite set of concepts. End users can then query the text using a predefined set of questions, each of which identifies a subset of complementary concepts. The search process matches that subset of concepts to relevant points in the text. The current process requires that the DE invest significant time to generate the required concepts and questions. We propose a new system--called ACQUIRE (Acquisition of Concepts and Queries in an Integrated Retrieval Environment)--that assists a DE in two essential tasks in the text-markup process. First, it helps her to develop, edit, and maintain the concept model: the set of concepts with which she marks the text. Second, ACQUIRE helps her to develop a query model: the set of specific questions that end users can later use to search the marked text. The DE incorporates concepts from the concept model when she creates the questions in the query model. The major benefit of the ACQUIRE system is a reduction in the time and effort required for the text-markup process. We compared the process of concept- and query-model creation using ACQUIRE to the process used in previous work by rebuilding two existing models that we previously constructed manually. We observed a significant decrease in the time required to build and maintain the concept and query models.

Abstracting and Indexing↗
PubMed1999

[An investigation of small marker chromosome in eight Turner syndrome patients by fluorescence in situ hybridization and DNA analysis].

OBJECTIVE: To direct genetic counseling and identify the origin of small marker chromosome in patients with Turner syndrome stigmata. METHODS: The specific primer on the sex determining region on Y (SRY) and biotin labeled X- and Y-chromosome DNA probes were utilized in the analysis of sex chromosome-derived markers. The PCR product from the amplification was detected on agarose gel, and fluorescence in situ hybridization (FISH) was conducted to metaphase chromosome. RESULTS: In 8 patients who had a small marker chromosome, five markers were derived from the X chromosome and three from the Y chromosome. Two patients with a Y-derived marker were determined by Y-chromosome probe as well as by SRY sequences amplification. One patient with a Y-derived marker was only demonstrated by FISH. CONCLUSION: The findings of this study demonstrate successfully the value and necessity of FISH utilizing DNA probes combined with specific amplification on SRY gene in the identification of sex chromosome marker. Such identification is important not only for clinical care, but also for understanding phenotype-karyotype correlations.

DNA-Binding Proteins↗
PubMed1999

[Effects of low-dose FP therapy for advanced gastric cancer cases].

The clinical application of low-dose FP therapy has spread rapidly in Japan. We examined the effects of this form of chemotherapy on patients with advanced gastric carcinoma in China. One cycle of this therapy consisted of intermittent infusion of CDDP (10 mg/body/3 hr), followed by intermittent infusion of 5-FU (250 mg/body/6 hr) and suppository administration of tegafur (500 mg) at night for 5 days with 2-day intervals. As a result, a partial response for the primary lesion and lymph nodes was obtained in some cases, 2 of which are described in this paper. No serious side effects were noted, although administration continued over a long period. Our results suggest that neoadjuvant chemotherapy with low-dose FP may be useful as an inductive approach for advanced gastric cancer, and that the regimen can become a standard therapy for gastric cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

[Cellular immunity and epidemiologic analysis of pediatric patients with Mycoplasma pneumonia].

OBJECTIVE: To understand the of immuno-reactions of pediatrics patients with Mycoplasma pneumonia. METHODS: 90 patients suffered from M. pneumonia were administered and divided into three groups: mild group, severe group, and normal control group. T cell subset parameters, natural killer cell and the serumsoluble interleukin-2 recepter of all of above were determined. RESULTS: Data showed:CD4 decreased at both acute and recovery stage of M. pneumonia, while CD8 remarkably increased (t = 2.63, 66, 2.77, 3.36, P < 0.05). SIL-2R level of all patients also greatly increased (t = 5.26, 3.19, P < 0.01), especially in the serious group. CONCLUSION: There are disturbances of cell-immune in M. pneumonia. The level of SIL-2R can serve as monitor on the degree of severeness of M. pneumonia. The incidence M. pneumonia appeared highest in the 10-14 year-old group.

Adolescent↗
PubMed1999

[Clinical study on transvaginal hysterectomy for moderate enlarged uterus].

OBJECTIVE: To assess the feasibility and safety of performing transvaginal hysterectomy(TVH) on moderate enlarged uteri. METHODS: Twenty-five transvaginal hysterectomies were performed on enlarged myomatous uteri, with the size equivalent to 12-17 gestational week or 280-570 g. Bisection, enucleation, morcellation and combinations thereof were used to facilitate the operation by reducing the uterine volume. The operation time, blood loss, morbidity as well as complications were observed and analyzed. RESULTS: Twenty-two out of 25 vaginal hysterectomies were successfully completed with a success rate of 88%. Another 3 cases were converted to transabdominal hysterectomies, 2 of them were due to technical difficulties. One bladder injury and one severe intraoperative hemorrhage occurred. Two cases required blood transfusion. The mean operating time was (119 +/- 32) min. The mean blood loss was (231 +/- 107) ml with a range of 100-500 ml except the case with severe hemorrhage. The morbidity rate was as low as 4% and the average postoperative hospital stay was (5.5 +/- 1.1) days. The follow-up at 2-48 months after operation showed excellent recovery in all cases without any late postoperative complications. CONCLUSION: In the hands of experienced vaginal operation surgeons some of the enlarged uteri(> or = 12 weeks gestational size, i.e. > or = 280 g) with benign disease can be safely removed transvaginally through reduction of uterine volume if the uterus is mobile and obtaind more satisfactory recovery.

Adult↗
PubMed1999

[Comparing immunogenicity and efficacy of two hepatitis B vaccines in newborn infants of hepatitis B surface antigen (+)/hepatitis B e antigen (+) carrier mothers].

OBJECTIVE: To evaluate the effect of yeast recombinant HBV vaccine on protecting the newborns from HBV carrier mothers and to compare with plasma-derived vaccine. METHODS: There were 117 neonates from HBsAg(+)/HBeAg(+) carrier mothers involved in the study. Study group [76 of them received RECOMBIVAX HB(5 mcg/0.5 ml)] and control group (41 neonates receive plasma derived vaccine) had blood samples collected and received vaccine at 0, 1, 6, 9 month after birth respectively. HBV-DNA, HBsAg/HBeAg, HBsAb were determined by PCR, ELISA, RIA independently. RESULTS: (1) Children chronic HBV infection rates at 6, 9 month of age in study group were 7.89%, 5.26% respectively, which were lower than that of control group(14.63%, 17.07%). (2) The vaccine efficacy (VE) in study group was 93.82%, vs, that of control group was 79.92%. (3) The HBsAb positive rate in study group at 9 month of age was 94.74% which was significantly higher than that of control group(80.49%) (P < 0.05). (4) The difference of side-effect rates between the two groups was not significant. CONCLUSION: Immunogenicity and efficacy of yeast-recombinant hepatitis B vaccine is better than that of plasma derived vaccine in newborn infants of HBsAg(+)/HBeAg(+) carrier mothers.

Adult↗
PubMed1999

[Intrapulmonary expression of tumor necrosis factor alpha mRNA and its significance in rats with acute pancreatitis].

It is thought that tumor necrosis factor (TNF) plays an important role in pathogenesis of acute lung injury or ARDS. So we want to get insight into the relationship between intrapulmonary expression of TNF-alpha gene and lung injury during acute necrotizing pancreatitis (ANP). In our study, acute edematous pancreatitis (AEP) and ANP were induced in rats by caerulein and sodium taurocholate respectively. After acute pancreatitis was induced, serum TNF-alpha was assessed by ELISA assay while endotoxin was assessed by limulus lysate test. Intrapulmonary expression of TNF-alpha mRNA was detected by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) technique. Moreover, content of pulmonary lesion was investigated and graded with microscope. It was found that TNF-alpha concentration in blood elevated markedly after acute pancreatitis was induced, especially in ANP group. Results of RT-PCR revealed that no TNF-alpha mRNA could be detected in lung tissue from those rats undergoing sham-operation, but marked expression appeared 1 hour after AEP or ANP was induced. Upregulation of expression of TNF-alpha gene in the early 3 hours was similar in the two groups with pancreatitis, and since then expression of TNF-alpha mRNA in ANP group was stronger than that in AEP group. Serum endotoxin increased significantly 6 hours after ANP was induced, with a higher level at 12 hour. However, there was no marked change of endotoxin level in AEP group and control group. It is noted that intrapulmonary expression of TNF-alpha gene in ANP group reached its peak as soon as serum endotoxin increased markedly. Lung damage in ANP group was more serious than that in AEP group significantly. Score of lung injury correlated well with TNF-alpha concentration in blood and expression of its gene in lung tissue in either AEP group or ANP group, as well as with serum endotoxin in ANP group. So overwhelm expression of some harmful cytokines like TNF-alpha in lung tissue may be the main cause of lung injury during acute necrotizing pancreatitis, and stimulation of endotoxiemia can at least partly explain the upregulation of expression of TNF-alpha gene.

Animals↗
PubMed1999

[Pharmacokinetics of pramiracetam in animals].

Pharmacokinetic rules of pramiracetam were studied here. After giving pramiracetam orally to dogs, we drew their blood at various times. The drug concentrations in blood plasma were detected by HPLC. 3p87 program was used to calculate the pharmacokinetic parameters. The time-concentration curve corresponded to one apartment model. T1/2 was about 2.3-3.9 hours in various doses. After pramiracetam was given to rats per os, high concentrations of pramiracetam were detected in the rats' tissues. The kidney had the highest concentration of pramiracetam; the liver had the next highest concentration, and then the intestine, lung, muscle, heart, gonad, spleen and sebum had the high concentration in order. The drug was also detected in the brain. 0.7% of the given dose was excreted in unchanged form in bile in 24 hours. 28.26% and 6.35% were excreted in urine and feces respectively in 72 hours. The plasma protein combining rate detected by the method of balance dialysis was 20.1-22.2%.

Animals↗
PubMed1999

[One simple and efficient method for purification of IgG McAb from mice ascites: caprylic acid/ammonium sulfate precipitation].

Several ascitic IgG McAbs were purificated by caprylic acid/ammonium sulfate precipitation (CA-AS), ammonium sulfate precipitation (AS) and SPA affinity chromatography. Purity of IgG purificated by CA-AS ranged from 87% to 91%, higher than that obtained by CA (65%-70%), lower than that obtained by SPA affinity chromatography (100%). The yield of IgG purificated by CA-AS ranged from 4.8 g/L to 5.5 g/L, lower than that obtained by CA (7.0-7.9 g/L), more higher than that obtained by SPA affinity chromatography (0.6 g/L). The recovery of IgG purificatied by CA-AS ranged from 39.0% to 44.4%, lower than that obtained by CA (56.0%-65.0%), more higher than that obtained by SPA affinity chromatography (7.4%). The ELISA titer of 4E2 or H6McAb was not impaired by purification of CA-AS. The above results suggested that CA-AS is one simple, efficient, rapid and low-cost method for purification of IgG McAb from ascitic fluid.

Ammonium Sulfate↗
PubMed1999

[Diagnosis and treatment of true hermaphroditism: a report of 3 cases and a review of literature].

OBJECTIVE: This paper evaluates the importance of early diagnosis and systemic treatment of true hermaphroditism. METHODS: Three patients with true hermaphroditism, because of inaccurate diagnosis and improper treatment at their early ages, were put in a dilemma when they grew up. After correct diagnosis, they accepted sex determinative operations according to their selective gender role. RESULTS: Through plastic operations, the three patients turned to be a male and two females, with their long time depression being released. CONCLUSION: True hermaphroditism is a rare deformity of ambiguous genitalia characterised by the presence of both ovarian and testicular tissues in the same individual. It is a key point for the patient to form normal sex psyche and adapt society through early precise diagnosis, appropriate gender option and successful operation according to clinical appearances and tissue pathological examination.

Adult↗
PubMed1999

Schedule-dependent reversion of cisplatin resistance by 5-fluorouracil in a cisplatin-resistant human lung adenocarcinoma cell line A549DDP.

OBJECTIVE: To study the schedule-dependent reversion of cis-diamminedichloroplatinum (CDDP) resistance by 5-fluorouracil (5-Fu) in a CDDP resistant human lung adenocarcinoma cell line A549DDP. METHODS: Dimethylthiazol dipheryltetrazolium bromide (MTT) assay and immunocytochemistry were used. RESULTS: After the A549DDP was treated with CDDP, followed immediately by exposure to 5-Fu, cytotoxicity of CDDP increased 1.8 fold. After pretreatment of A549DDP with 5-Fu, followed immediately by exposure to CDDP, the cytotoxicity of CDDP increased 3.9 fold. After pretreatment of A549DDP with 5-Fu, after a 24- or 48-hour drug-free interval, followed by exposure to CDDP, the cytotoxicity of CDDP increased 20 and 250 fold, respectively, and the A549DDP was rendered more sensitive than its parental cell line A549. In parallel with the increased cytotoxicity, the cellular GSH content was significantly reduced at 24 or 48-hour after 5-Fu pretreatment. However, depletion of GSH by buthionine sulfoximine (BSO) only resulted in partial reversion of CDDP resistance. 5-Fu could also inhibit the expression of MRP, but had no effect on the expression of GST pi. The effect of 5-Fu on the parental cell line A549 was much smaller than that in A549DDP. CONCLUSION: Scheduled administration of 5-Fu can reverse CDDP resistance completely through reduction of GSH and inhibition of MRP expression.

Adenocarcinoma↗