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L Liu

Publications and source records attributed to L Liu.

At least 559 records · Page 31Linked to original sources
PubMed1999

Guidelines for the pediatric perioperative anesthesia environment. American Academy of Pediatrics. Section on Anesthesiology.

The American Academy of Pediatrics proposes the following guidelines for the pediatric perioperative anesthesia environment. Essential components are identified that make the perioperative environment satisfactory for the anesthesia care of infants and children. Such an environment promotes the safety and wellbeing of infants and children by reducing the risk for adverse events.

Anesthesia↗
PubMed1999

Laser-induced fluorescence (LIF) recognition of the structural composition of porcine heart valves.

Reconstruction and replacement of heart valves with grafts fro pig tissue is a common procedure. However, bioprosthetic valves wear out in a shorter time span than mechanical valves. Bioprosthetic valve structure may contribute to degenerative changes that lead to valve failure. There is, at present, no method to examine the structure of a tissue valve prior to implant. Laser-induced fluorescence (LIF) of natural fluorophores is an elegant method developed for the detection of tumors, dermal lesions and atherosclerosis. We have studied LIF as a potential diagnostic technique for analysis of valvular tissue. Using excimer laser excitation, we examined natural fluorescence recorded from porcine aortic, mitral and pulmonary valves. All three valve outflow surface tissue layers are less fluorescent at 390-450 nm than the inflow layers. Immunohistochemical analysis of collagen I and elastin content in inflow and outflow surface layers of all three valves correlated well with LIF intensities and dI/d lambda values at selected wavelengths. In conclusion, the differences observed in emitted LIF from valve surface layers are found to correlate well with diversity in the structural protein content. The LIF spectroscopic measurements may provide an appropriate tool for examination of tissue valve structure prior to use for implantation.

Animals↗
PubMed1999

Changes in body mass index and its relationships to other cardiovascular risk factors among Japanese population: results from the 1980 and 1990 national cardiovascular surveys in Japan.

Few studies have attempted to investigate the changes in body mass index (BMI) and its relationship to other cardiovascular factors in Asian populations, including Japanese. Data from two national cross-sectional surveys on circulatory disorders in 1980 and 1990 in Japan were used in this study. The sample consisted of 10,556 participants in the 1980 survey and 8,385 in the 1990 survey, aged > or = 30 years. The results show that after adjusting for age, smoking, alcohol consumption (ALC) and daily life physical activity (PA), mean BMI increased 0.49 kg/m2 (95% confidence interval: 0.34-0.65) in men aged 30-59 and 0.61 kg/m2 (0.37-0.86) in those aged > or = 60 from 1980 to 1990. In women, however, mean BMI decreased 0.24 kg/m2 (-0.39 0.09) in those aged 30-59 and increased 0.38 kg/m2 (0.12-0.64) in those aged > or = 60. BMI was significantly associated with hypertension, diabetes and hypercholesterolaemia. In both genders, cu-smokers had lower mean BMI than never smokers, while among the cu-smokers, mean BMI was positively associated with the number of cigarettes smoked per day. In men, BMI was positively associated with ALC and negatively associated with PA, while in women, BMI was negatively associated with ALC and positively associated with PA. The results suggest that BMI has significantly increased in men and in elderly women. BMI, even in the Japanese population who are characterized by relative low BMI, is significantly associated with several cardiovascular risk factors.

Adult↗
PubMed1999

Evaluation of porous collagen membrane in guided tissue regeneration.

Porous collagen membrane was prepared with collagen protein, which was extracted from bovine tendon by enzyme digestion, by freeze-drying method. The animal, clinical experiments of the membrane used in artificial dental implant system were studied. In the animal experiments, pure titanium spiral implants, which were prepared according to Adell etc. method, were implanted in the mandibular dental alveus of adult hybrid dog and covered with collagen membrane. Then the animals were killed after 4, 18 weeks individually. In the clinical research, the implants (phi 3.3 mm) were used in 33 patients of different age groups. The implant was put on the buccal lateral deficiency of implantation cavity wall, and covered with collagen membrane on the buccal lateral, then observed after 3, 6 months individually. The results of animal experiments proved the collagen membrane could guide osseous tissue regeneration around the bone integral implant which was implanted in the fresh tooth extraction fossa, be helpful to repair the fissural bone deficiency produced when implanted the implant, increase the bone content around the implant significantly, and improve the structure of new bone to a certain extent. The results of clinical research proved that collagen membrane was used in the patients with density deficiency, irregularity of alveolar ridge, or artificial dental of shorter tooth extraction, could significantly improved the bone density of artificial implant's shoulder.

Adult↗
PubMed1999

Peroxisome proliferator-activated receptor gamma activation in human breast cancer.

The peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor family of ligand-activated transcription factors. This study was designed to evaluate ligand activation of PPARgamma in human breast cancer cells. DNA binding by endogenous PPARgamma in gel shift assays and activation of PPARgamma by prostanoid and thiazolidinedione ligands in reporter gene assays differed between the cell lines. The PPARgamma ligands elicited an anti-proliferative effect in MTT proliferation assays. Our data point to a variable, cell-specific response to different gamma-ligands, which holds significance for further studies on the role of PPARgamma in mediating breast cancer growth and progression.

Breast Neoplasms↗
PubMed1999

Leukocyte O6-alkylguanine-DNA alkyltransferase from human donors is uniformly sensitive to O6-benzylguanine.

O6-Alkylguanine-DNA alkyltransferase (AGT) is the key DNA repair protein responsible for resistance to chloroethylating and methylating agents that attack at the O6 position of guanine. O6-Benzylguanine (BG), a potent inhibitor of AGT, has recently entered clinical trials. A number of point mutations and at least one human polymorphism within AGT are associated with AGT resistance to inactivation by BG. In this study, we evaluated AGT inhibition by BG in an in vitro assay of peripheral blood mononuclear cell AGT from 56 normal donors, 42 Caucasians, and 14 Japanese. AGT activity ranged from 2.7 to 21.9 fmol/microg DNA and was similar in Japanese and Caucasian donors. Depletion of AGT by BG was uniform in all donors with mean ED50s of 037 microM BG in Caucasians and 0.36 microM BG in Japanese. To determine whether the gly160arg AGT polymorphism described in the Japanese population, and recently shown to be BG resistant, could be detected by this assay, we mixed purified gly160arg AGT protein with blood mononuclear cell extract and measured in vitro BG inactivation. The ED50 for the mixture of the gly160arg AGT and mononuclear cell extract was 9 microM BG. On the basis of results in 56 donors, we conclude that BG-resistant AGT, defined as an ED50 in mononuclear cells of >1 microM BG, is present in 0 of 56 donors, (95% confidence interval, 0-6%), suggesting that polymorphisms producing AGT-resistant BG are unusual in humans.

Alkyl and Aryl Transferases↗
PubMed1999

[Genetic linkage of polymorphisms of type I angiotensin II receptor gene to Chinese Han hypertension].

OBJECTIVE: To observe the CA repeat polymorphism of the type I angiotensin II receptor gene on Chinese Han people, and evaluate the genetic linking to hypertension. METHODS: The CA repeat polymorphism at 3'-flanking region of AT1R gene was studied by amplified fragment length polymorphism (Amp-FLP ) in Chinese Han people from Shandong and Xi'an. RESULTS: There were 9 alleles ranging from 130bp to 146bp in all subjects. The allele frequencies were 0.01 to 0.38, and allele A4 was more frequent in the control. The heterozygosity of CA repeat locus was 0.789, the polymorphic information content, 0.746. There was no significant difference in distribution of CA repeat polymorphism genotype between different regions in same ethnic (P>0. 05), but the allele frequency of CA repeat polymorphism in hypertensive group was significantly different from that of control (P<0.05). There was no detectable distortion from Hardy-Weinberg equilibrium in both groups. CONCLUSION: The results suggest that CA repeat polymorphism of AT1R gene be associated with Chinese Han hypertensive people.

Adult↗
PubMed1999

Hereditary absence of complement C5 in adult mice influences Wallerian degeneration, but not retrograde responses, following injury to peripheral nerve.

We have examined the role of complement component 5 (C5) in peripheral nerve fiber degeneration and regeneration, as well as in glial and neuronal cell responses in the central nervous system (CNS). Adult congenic mice lacking C5 (C5(-)) and the corresponding normal strain (C5(+)) were used. Macrophage recruitment as well as axonal and myelin sheath elimination were delayed from 1 to 21 days postinjury in C5(-) mice compared to the C5(+) group after sciatic nerve crush. Despite this, recovery of motor function was not delayed. In the CNS, microglial cells and astrocytes responded in the same way from 3 to 21 days after sciatic nerve injury in C5(-) and C5(+) mice, and the extent of neuron death following hypoglossal nerve avulsion was the same in both groups. These findings suggest that C5 and/or its derivatives play an important role in initiating the recruitment of macrophages to the injured nerve and, probably indirectly, in early remyelination of regenerating axons, but does not influence the longterm functional restoration or axotomy-induced nerve cell death. C5-derived molecules do not appear to participate in central glial cell responses to peripheral nerve injury. These findings elucidate new aspects on the functional role of the complement system in the peripheral nervous system following peripheral nerve injury.

Animals↗
PubMed1999

Retirement income security in the United Kingdom.

This article examines the U.K. retirement income security system from the American perspective. It addresses issues that most concern U.S. analysts: how the United Kingdom has kept its future public pension costs at a manageable level, the extent to which privatization of public pensions has contributed to low pension costs, the popular appeal of individual pension accounts, and the impact of privatization on retirement income. These issues are best understood in the context of the U.K. pension program's particular institutional structure and policies, two of which--"contracting out" of public pensions, and strong reliance on means-tested benefits--have been largely rejected in the evolution of U.S. policy to date. Particular use is made of recently available data on coverage rates for public and private pension programs over the total working population and administrative records on inactive personal pension accounts.

Contract Services↗
PubMed1999

Adrenocortical response profiles to corticotrophin-releasing hormone and adrenocorticotrophin challenge in the chronically catheterized adult guinea-pig.

The guinea-pig has been used extensively to investigate adrenal steroidogenesis. However, very little is known about adrenocortical responses to corticotrophin-releasing hormone (CRH) and adrenocorticotrophin (ACTH) in this species, in vivo. In the present study, we have developed a stress-free sampling system, in the chronically catheterized adult guinea-pig, that has allowed us to investigate basal and activated adrenocortical activity. Indwelling carotid artery and jugular vein catheters were surgically implanted into female guinea-pigs (n = 5). Each animal was treated with vehicle, human CRH (0.2 or 2 microg kg-1) and ACTH1-24 (0.2 or 2 microg kg-1), and serial plasma samples removed for analysis of ACTH and cortisol concentrations by radioimmunoassay. There was no effect of serial sampling on pituitary-adrenocortical activity, indicating that the animals remain in an unstressed state. Basal plasma ACTH and cortisol concentrations were 703.9 +/- 24.5 pg ml-1 and 117.9 +/- 5.2 ng ml-1, respectively. Both CRH and ACTH significantly increased adrenocortical activity in a dose-dependent manner. ACTH (2 microg kg-1) was the most potent activator leading to plasma cortisol concentrations of 647 +/- 116 ng ml-1. In conclusion, we have shown that basal plasma cortisol concentrations in the guinea-pig are low compared to those obtained in previous studies by cardiac puncture or following decapitation. However, plasma ACTH concentrations are high compared to other species. We have also shown that human CRH and ACTH1-24 act as potent activators of the guinea-pig pituitary-adrenocortical axis, leading to response profiles consistent with mild cortisol resistance.

Adrenal Cortex↗
PubMed1999

Pharmacologic disruption of base excision repair sensitizes mismatch repair-deficient and -proficient colon cancer cells to methylating agents.

Previously we showed that a mismatch repair (MMR)-deficient cell line, HCT116 (hMLH1 mut), unlike a MMR wild-type cell line, SW480, was more resistant to the therapeutic methylating agent, temozolomide (TMZ), because the MMR complex fails to recognize TMZ-induced O6-methylguanine DNA adduct mispairings with thymine that arise after replication. TMZ also produces N7-methylguanine and N3-methyladenine adducts that are processed efficiently by the base excision repair (BER) system. After removal of the methylated base by methylpurine glycosylase, which creates the abasic or apurinic-apyrimidinic (AP) site, the phosphodiester bond is hydrolyzed immediately by AP endonuclease, initiating the repair of the AP site. Methoxyamine (MX) reacts with the abasic site and prevents AP endonuclease cleavage, disrupting DNA repair. MX potentiated the cytotoxic effect of TMZ with a dose modification factor (DMF) of 2.3+/-0.12 in SW480 and 3.1+/-0.16 in HCT116. When combined with O6-benzylguanine (BG), MX and TMZ dramatically increased TMZ cytotoxicity (65.8-fold) in SW480, whereas no additive effect was seen in HCT116. This suggests that N7-methylguanine and N3-methyladenine adducts are cytotoxic lesions in MMR-deficient and wild-type cells when BER is interrupted. Because poly(ADP-ribose) polymerase (PARP) aids in processing of DNA strand breaks induced during MMR and BER, we asked whether PARP inhibitors would also affect BER-mediated cell killing. We found that PARP inhibitors PD128763, 3-aminobenzimide, and 6-aminonicotinamide increased the sensitivity to TMZ in both HCT116 MMR-deficient cells and SW480 MMR wild-type cells. In HCT116 cells, PD128763 remarkably decreased resistance to TMZ, with a DMF of 4.7+/-0.2. However, the combination of PD128763, BG, and TMZ had no greater effect, indicating that persistent O6-methylguanine had no effect on cytotoxicity. In SW480, the DMF for TMZ cytotoxicity was 3.1+/-0.12 with addition of PD128763 and 36 with addition of PD128763 and BG. Synergy analysis by median effect plots indicated a high degree of synergy between TMZ and MX or PD128763. In contrast, 1,3-bis(2-chloroethyl)-1-nitrosourea combined with either MX or PD128763 showed little if any potentiation observed in the absence of BG in either cell line, suggesting that BER pathway has little impact on cytotoxic processing of 1,3-bis(2-chloroethyl)-1-nitrosourea-induced adducts. These studies indicate that targeting BER with MX or PARP inhibitors enhances the cytotoxicity of methylating agents, even in MMR-deficient cells.

Antineoplastic Agents, Alkylating↗
PubMed1999

[Matched case-control study for detecting risk factors of breast cancer in women living in Chengdu].

OBJECTIVE: To detect the risk factors of breast cancer in women living in Chengdu in order to identify high risk population and to conduct proper interventions. METHODS: A matched case-control study was performed in 265 cases with breast cancer who lived in this area. RESULTS: In the univariate analysis, menarche to menopause period > or = 35 years, taking oral contraceptives, history of benign breast diseases, passive smoking, and syrup drinking are the statistically significant risk factors of breast cancer, whereas breast feeding and soybean food consumption are protective factors. Conditional logistic multivariate analysis revealed that history of benign breast diseases and passive smoking are risk factors while soybean food products and breast feeding are protective factors. CONCLUSION: The risk factors of breast cancer in women living in Chengdu are history of benign breast diseases and passive smoking.

Adolescent↗
PubMed1999

Sandwiched osmotic tablet core for nifedipine controlled delivery.

The sandwiched osmotic tablet core, which is composed of a middle push layer and two attached drug layers, has been prepared and systematically studied with the purpose of delivering water-insoluble nifedipine. The advantage of the sandwiched osmotic tablet system over the commercialized push-pull osmotic tablet system is its simplicity of preparation, as the surface identification was avoided. It was observed that polyethylene oxides (PEO) with molecular weight (MW) of 300,000 and 8,000,000 g/mole were suitable for the thickening agent of drug layer and the expandable hydrogel of push layer, respectively. The weight ratio of 190/190 for drug layer/push layer was also found to be suitable. It has been observed that PEO amount of the push layer and the KCl amount of the drug layer had profoundly positive influence on nifedipine release. A push layer/drug layer co-controlled osmotic delivery mechanism has been proposed and the optimal tablet formulation has been obtained. It was also found that PEO and nifedipine were miscible, which may support the application of PEO in nifedipine dosage forms. Meanwhile, the PEO/nifedipine binary phase diagram has been constructed. The sandwiched osmotic tablet system can deliver nifedipine in an approximate zero-order rate up to 24 hours. It may be potentially used for the delivery of water-insoluble drugs.

Calcium Channel Blockers↗
PubMed1999

[Chromosomal mapping of ld gene which causes congenital limb deformity syndrome in KM-ld mouse].

Fourteen biochemical marker loci and 61 SSLP loci in congenic strain C57BL/6.KM-ld were screened to determine the loci linkage to ld gene, an autosomal recessive mutant gene in KM mouse which causes congenital limb deformity in mouse by means of electrophoresis and PCR amplification. The result showed that ld gene linked to D2Mit30, D2Mit62 and D2Mit63. To locate ld gene more accurately on chromosome 2, 86 backcross offsprings (C57BL/6 x KM-ld) F1 x KM-ld were produced for linkage analysis. From the backcross progeny genomic DNAs were amplified for D2Mit13, D2Mit30, D2Mit62 and D2Mit63 loci in vitro. According to phenotypes, the linkage between the four SSLP loci and ld gene was analysed by calculating genetic distance, ld gene was located exactly on Chr. 2, 76cM, with distances of 25.58cM to D2Mit30, D2Mit62 and D2Mit63, of 31.39cM to D2Mit13.

Animals↗
PubMed1999

[A study on C-erbB2, nm23 and p53 expressions in epithelial ovarian cancer and their clinical significance].

OBJECTIVE: To investigate the expressions of C-erbB2, nm23 and p53 in epithelial ovarian cancer and their clinical significance. METHODS: Expression of C-erbB2, nm23 and p53 proteins was retrospectively studied by immunohistochemistry, and Kaplan-Meier Method and Cox's proportional hazard regression model were used to analyze the relationship of their expressions with prognosis. RESULTS: (1) The expression rate of C-erbB2 was 31.4%, and was in connection with clinical stage. (2) The expression rate of nm23 was 38.6%, while it maybe correlated with pelvic lymph node metastasis. (3) The expression rate of p53 was 34.3%, and the rate was higher in serous ovarian cancer than in mucinous. (4) There was no correlation among the expression of the three proteins. (5) Survival follow-up data showed that mean survival time was shorter in patients with C-erbB2 expression than those without; and nm23 and p53 were not significantly related to survival time. Multivariate Cox's proportional hazard regression model analysis suggest that C-erbB2 expression clinical stage and residual tumor size were three variates significantly contributing to patients prognosis. CONCLUSIONS: C-erbB2 expression has a close relationship with malignancy degree of epithelial ovarian cancer, and significantly contributes to prognosis. p53 expression correlates with its subtype and nm23 with its status of pelvic lymph node metastasis, however, neither contributes to prognosis.

Adult↗
PubMed1999

[GB virus-C infection in Chinese patients with hepatocellular carcinoma].

Hepatitis B and C viruses (HBV, HCV) are closely related with hepatocellular carcinoma(HCC). The association between the new discovered GB-virus C (GBV-C) and HCC has not yet been known. In this study, 124 HCC patients were detected for the prevalence of GBV-C RNA by the one-step nested reverse transcription polymerase chain reaction (RT-PCR) and followed by hybridization using GBV-C probes located at 3'-untranslated region (3'-UTR) from its reported genomes. The results showed that 33 of 124 (26.6%) HCC cases were GBV-C RNA positive, including 12 cases positive HBsAg and anti-HCV, and 3 for cases negative HBsAg and anti-HCV. The clinical background of the patients with HBsAg and/or anti-HCV who were also positive for GBV-C RNA did not differ from the background of those who were negative for GBV-C RNA except the ratio of blood transfusion history. In conclusion, GBV-C has a high prevalence in Chinese HCC patients. Even though no sufficient data supports the causality of GBV-C on hepatocarcinogenesis, further researches aimed at whether GBV-C infection aggravates the incidence of HCC are warranted.

Adult↗