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Biomedical subjects

B Liu

Publications and source records attributed to B Liu.

At least 505 records · Page 28Linked to original sources
PubMed1996

Cardiac efficiency is improved after ischemia by altering both the source and fate of protons.

Cardiac efficiency is decreased in hearts after severe ischemia. We determined whether reducing the production of H+ from glucose metabolism or inhibiting the clearance of H+ via Na(+)-H+ exchange could increase cardiac efficiency during reperfusion. This was achieved using dichloroacetate (DCA) to stimulate glucose oxidation and 5-(N,N-dimethyl)-amiloride (DMA) to inhibit Na(+)-H+ exchange, respectively. Isolated working rat hearts were subjected to 30 minutes of global ischemia and 60 minutes of reperfusion. Glycolysis and oxidation rates of glucose, lactate, and palmitate were measured. Recovery of cardiac work, O2 consumption (MVO2), and rates of acetyl-coenzyme A and ATP production during reperfusion were determined. After ischemia, cardiac work recovered to 35 +/- 5% of preischemic values in control hearts (n = 23), although MVO2, tricarboxylic acid (TCA) cycle activity, and ATP production from glycolysis and oxidative metabolism rapidly recovered to preischemic levels. This decrease in cardiac efficiency was accompanied by a substantial production of H+ from glucose metabolism DCA caused a 2.2-fold increase in glucose oxidation, a 46 +/- 17% decrease in H+ production, a 1.6-fold increase in cardiac efficiency, and a 2.0-fold increase in cardiac work during reperfusion (n = 17). Inhibition of Na(+)-H+ exchange with DMA did not alter TCA cycle activity and ATP production rates but did result in a 1.8-fold increase in cardiac efficiency and a 1.7-fold increase in cardiac work (n = 12). These data show that cardiac efficiency and the contractile function after ischemia can be improved by either reducing the rate of H+ production from glucose metabolism during reperfusion or inhibiting the clearance of H+ via Na(+)-H+ exchange. Our data suggest that an increased requirement for ATP to restore ischemia-reperfusion-induced alterations in ion homeostasis contributes to the decrease in cardiac efficiency and contractile function after ischemia.

Acetyl Coenzyme A↗
PubMed1996

Factors influencing haemostasis and blood transfusion in cardiac surgery.

To find out the risk factors influencing perioperative bleeding and use of blood products in cardiac surgery so that appropriate interventions can be selected for blood conservation, risk factors were analysed in 343 cardiac surgical patients, retrospectively, by multiple regression technique. The results showed that the factors related to postoperative bleeding were male gender, Higgins score, cardiopulmonary bypass (CPB) time, operation procedures, intraoperative blood loss and use of internal mammary artery (IMA) graft. Factors related to perioperative homologous blood transfusions were emergency surgery, preoperative haemoglobin level, Higgins score, intraoperative blood loss, operation time and operation procedures. The geometric mean of postoperative bleeding in the entire series was 1085 ml and the mean packed red cell, plasma and platelet transfusions were 3.29 +/- 0.4, 1.96 +/- 0.39 and 0.21 +/- 0.05 units respectively. The incidence of homologous blood transfusion during the hospital stay was 58.9% for the entire series and 54.5% in the nonrevision patients. Emergency patients received significantly more blood transfusion (p = 0.0001). Perioperative blood loss and transfusions are still problems in cardiac surgery and certain patient groups in this study were identified as high risk; available blood conservation techniques, therefore, are recommended in these patients.

Blood Transfusion↗
PubMed1996

Cardiopulmonary bypass support for treatment of left ventricular failure following coronary artery bypass grafting: the effects on epicardial microflow and graft flow.

The relationship between graft blood flow, epicardial microflow and mean arterial pressure were studied to evaluate the use of repeated cardiopulmonary bypass (CPB) support for intraoperative heart failure following aorto-coronary bypass surgery. Ten patients with unstable angina and suffering from intraoperative heart failure (group A) were compared to 22 patients with stable angina (group B). In group A, during heart failure, the mean arterial pressure fell by 41% (29.9 +/- 6.8 mmHg, p < 0.01), graft flow (GF) by 67% (9.2 +/- 2.6 ml/min, p < 0.01) and epicardial microflow by 64% (19 +/- 4 AU, p < 0.01). After 15-56 min of assisted CPB support, the epicardial microflow and GF were partially restored. There were significant correlations between GF, epicardial microflow and CPB time. In group B, after protamine infusion, the epicardial microflow and GF were significantly greater than group A values (66 +/- 14 AU, p < 0.001 and 29 +/- 9 ml/min, p < 0.001, respectively). It is concluded that the use of temporary assisted CPB support to treat intraoperative heart failure allows the recovery of the myocardium and thereby restores the mean arterial pressure. The recovery of GF and epicardial flow occurred to a lesser extent. CPB support appeared to be suitable for about 60 min, probably because of increasing disturbance to the GF and the epicardial microcirculation.

Aged↗
PubMed1996

Association of protein kinase-C-alpha with cytoplasmic vesicles in melanoma cells.

In B16a melanoma cells, protein kinase-C-alpha (PKC alpha) is immunomorphologically associated with cytoplasmic vesicles in addition to the previously observed locations (plasma membrane, cytoskeleton, nucleus), as detected with monoclonal antibody (MAb) MC3a. Subcellular fractionation indicated that the authentic 80-KD protein as well as PKC activity can be detected in several particulate fractions except for L2, which contains dense lysosomes. The highest PKC activity is associated with the cytosol-ultralight vesicles and the L1 fraction (containing plasma membrane, endosomes, and the Golgi apparatus). Both of these fractions contained the fluid-phase endocytosis marker peroxidase, indicating that PKC alpha, in addition to other subcellular structures, is most probably associated with endosomal membranes in B16a melanoma cells.

Animals↗
PubMed1996

Prolactin-like protein-C variant: complementary deoxyribonucleic acid, unique six exon gene structure, and trophoblast cell-specific expression.

The rat placental PRL family consists of proteins structurally related to pituitary PRL. As a consequence of attempting to characterize the gene for one of the members of the family, PRL-like protein-C (PLP-C), we identified a related gene that we have termed PLP-C variant (PLP-Cv). In this study, we present information on the PLP-Cv gene and its pattern of expression. Screening of a rat genomic library with a PLP-C cDNA resulted in the isolation of four phage clones. Nucleotide sequence analysis of the clones revealed a gene, PLP-Cv, closely related but distinct from PLP-C. The PLP-Cv gene possessed a six exon/five intron organization, unique among members of the PRL family, and was localized to chromosome 17 of the rat genome, similar to other PRL family members. A PCR strategy involving primers based on the PLP-Cv gene was used to isolate a placental PLP-Cv cDNA. PLP-Cv showed 90 and 78% sequence identity with PLP-C at nucleotide and amino acid levels, respectively. Expression of PLP-Cv was restricted to the trophoblast lineage and was coordinately activated with PLP-C beginning at day 11 of gestation and continuing until term. Primer extension analysis revealed multiple putative transcription start sites. A 2.1-kilobase pair PLP-Cv promoter-luciferase reporter construct was specifically activated in differentiating rat trophoblast cells but not in other cell types. In conclusion, we have identified a new member of the PRL family possessing considerable homology to PLP-C, a unique gene structure, and displaying a trophoblast-specific pattern of transcriptional activation.

Amino Acid Sequence↗
PubMed1996

Rcho-1 trophoblast cell placental lactogens: complementary deoxyribonucleic acids, heterologous expression, and biological activities.

In this report, we have investigated placental lactogens (placental lactogen-I, PL-I; PL-I variant, PL-Iv; PL-II) expressed by differentiated Rcho-1 trophoblast cells. A complementary DNA (cDNA) library to differentiated Rcho-1 trophoblast cells was constructed and screened with probes to detect PL-I and PL-II. Sequence analysis of three independent Rcho-1 PL-I cDNAs indicated that they significantly differed from the previously reported PL-I sequence but more closely resembled a related cDNA referred to as PL-I mosaic (PL-Im). Upon further analysis, Rcho-1 PL-I/PL-Im transcripts could be detected in Rcho-1 trophoblast cells and normal developing placental tissue; however, the previously reported PL-I transcript could not be identified from the same sources. Given these results, we examined the original PL-I cDNA by PCR and nucleotide sequence analyses. The sequence differed from the original report and was found to be identical to the Rcho-1 PL-I and PL-Im cDNA clones. Thus, PL-I, Rcho-1 PL-I, and PL-Im are equivalent and should be referred to as PL-I. The PL-I gene was localized to chromosome 17 of the rat genome, similar to other PRL family members. Rcho-1 PL-II cDNAs were identical to the published PL-II sequence. PL-Iv cDNAs were isolated from differentiated Rcho-1 cells via an RT-PCR strategy and found to be identical to previously isolated PL-Iv cDNAs. Rcho-1 PL-I and PL-II cDNAs were subcloned into the pcDNA3 expression vector and recombinant protein produced in HRP-1 cells. Both recombinant Rcho-1 PL-I and PL-II proteins significantly stimulated the proliferation of lactogen-dependent rat Nb2 lymphoma cells and mouse mammary epithelial cells. In summary, we show that the Rcho-1 PL-I corresponds to PL-Im and Rcho-1 PL-Iv and PL-II are identical to their previously described placental counterparts. Additionally, both recombinant Rcho-1 PL-I and PL-II proteins are biologically active.

Animals↗
PubMed1996

Prolactin in the Cestodes, Taenia solium and Taenia hydatigena: an immunocytochemical study.

The demonstration of prolactin in cestodes, Taenia solium and Taenia hydatigena, was investigated by using immunocytochemical method. PRL immunoreactivity was widely distributed in the CNS and PNS in the worms. In the scolex PRL-IR perikarya occurred in the cerebral ganglia, around the basic area of the sucker and the rostral border region between the rostellum and the suckers with strong immunoreaction, distinctly in Taenia solium. A number of PRL-IR nerve fibres were observed in the main nerve cords, and a few fibres in the transverse nerve commissure. The holdfast musculature of the scolex was innervated by the PRL-IR fibres. A large number of PRL positive cells with processes and nerve plexuses were seen in the ootype/Mehlis' gland complex, oviduct, the duct of uterum, seminal receptacle and its associated duct, conspicuously in Taenia hydatigena. PRL-IR was evident in the wall of vas efferens of tests and vas deferens. A few PRL positive cells occurred in the medullary parenchyma amongst testes and sent their varicose processes to terminate to the testes. On the wall of the main excretory duct a few PRL-IR cells and fibres were seen.

Animals↗
PubMed1996

Ultrastructural study of neurosecretory cells in the nervous system in the cestode (Taenia hydatigena).

The neurosecretory cells in nervous system of the Taenia hydatigena was studied light- and electron-microscopically. On the basis of the cytological structure they were divided into two types: type I neurosecretory cells, which containing large dense-cored vesicles, small elongated mitochondria and a large amount of free ribosomes, were located mainly in the central and peripheral nervous system; type II neurosecretory cells were characterized by their moderate amount of free ribosomes, endoplasmic reticulum which contacted with the membranes of perikarya, large ovoid mitochondria, large dense-cored vesicles and their localization in the musculature near serve profiles. The synaptic and nonsynaptic contacts i.e. omega figure and exocytosis release sites were seen in the neuropile, musculature and excretory ducts. The present findings suggest that neurosecretory cells in nervous system may play an important integrative roles of both neuronal and endocrine in the flatworm.

Animals↗
PubMed1996

[Relation between loss of heterozygosity at APC and MCC genetic loci and biological behaviour of gastric carcinoma].

In order to detect loss of heterozygosity (LOH) at APC and MCC genetic loci in gastric carcinoma, the authors established a micro-wax-mediated hot start PCR technique. This method allowed a specific gene amplification, and it was useful especially in the amplification of formalin-fixed or stained tissues. In 44 cases of gastric cancer, 29 cases were informative of the APC locus. LOH was found in 8 cases (27.6%): 2 cases in 2 moderately well-differentiated cancer, 2 cases in 13 differentiated cancer, and 4 cases in poorly-differentiated cancer. One of the 3 cases of gastric cancer at early stage also showed LOH. LOH at MCC locus was detected in only 2 of the 25 (8.0%) gastric cancer patients informative. These data suggest that abnormality of APC gene plays a role in the tumorigenesis of gastric cancer and the change may occur at the early stage of tumor development.

Adenocarcinoma↗
PubMed1996

[The relationship between placental pathology and certain pathogens detected in paraffin-embedded tissues in cases of intrauterine growth retardation].

OBJECTIVE: To study the relationship between placental pathology and certain pathogens detected in paraffin-embedded placental tissues in cases of intrauterine growth retardation (IUGR). METHODS: The PCR-DNA techniques were used for determination of pathogens, including toxoplasma, cytomegalovirus and herps simplex type II in paraffin-embedded placental tissues from 53 cases of IUGR. RESULTS: Among 53 cases of IUGR, the pathogens were detected in 19 cases (35.85%). The relationships of pathogens detected to placental pathology were analyzed. Pathogens were found in 10 of 18 placentas with villitis, 7 of 11 placentas with villous maturation retarded and 2 of 3 intervillous space infections respectively. The incidence of infection in the pathological placentas was 59.38%. CONCLUSIONS: The study suggested that the haematogenous infections could play important roles in unknown causes of IUGR.

Adult↗
PubMed1996

Secretory expression of a single-chain insulin precursor in yeast and its conversion into human insulin.

A synthetic single-chain porcine insulin precursor (PIP) gene and an alpha-mating factor leader sequence (alpha MFL) gene obtained by the PCR method are inserted between the promoter and 3'-terminating sequence of the alcohol dehydrogenase gene ADH1 in plasmid pVT102-U to form plasmid pVT102-U/alpha MFL-PIP. The single-chain insulin precursor is expressed and secreted to the culture medium by Saccharomyces cerevisiae transformed by pVT102-U/alpha MFL-PIP. The precursor is purified and converted into human insulin by tryptic transpeptidation. The purified human insulin is fully active and can be crystallized. The overall yield of human insulin is 25 mg per liter of culture medium.

Base Sequence↗
PubMed1996

Cisplatin resistance and regulation of DNA repair in cAMP-dependent protein kinase mutants.

Drug resistance in cancer poses a major problem to the success of chemotherapy. Increased resistance to the DNA-damaging chemotherapeutic drug cisplatin may be associated with a variety of factors including decreased drug accumulation, increased intracellular levels of thiols, and increased DNA repair. We have found that mutants of the Chinese hamster ovary (CHO) and the mouse adrenocortical carcinoma Y1 cells harboring a defective regulatory subunit (RI) of the cAMP-dependent protein kinase (PKA) exhibited increased resistance to cisplatin. These mutants are cross-resistant to other DNA-damaging chemotherapeutic agents, including bleomycin and melphalan. In addition, wild-type CHO cells transfected with and overexpressing the yeast phosphodiesterase gene or a dominant mutant Rl alpha subunit gene also displayed similar increased resistance to cisplatin. However, mutants with altered catalytic (C) subunits showed a sensitivity to cisplatin similar to the wild-type cells. Further analysis by gel shift assay using cisplatin-damaged DNA as probes and nuclear extracts derived from the Rl subunit mutants showed increased binding of nuclear factor(s) to the damaged DNA. In addition, a host cell reactivation assay of DNA repair, using a cisplatin-damaged reporter plasmid, detected enhanced capacity for repair of DNA lesions in the PKA mutants. These results suggest that DNA repair may be increased in the PKA mutants. We speculate that functional inactivation of PKA may result in increased DNA repair and the acquisition of resistance to DNA-damaging anticancer drugs in cancer.

Adrenal Glands↗
PubMed1996

Effects of MTX and BN52021 on PAF-induced chemotaxis of PMNs and intraepidermal accumulation of inflammatory cells in guinea pigs.

OBJECTIVE: To investigate the effects of methotrexate (MTX) and platelet activating factor (PAF) antagonist ginkgolide B (BN52021) on PAF induced chemotaxis of neutrophils. MATERIALS AND METHODS: All guinea pigs were randomly divided into 12 groups. They were given different dosages of MTX and BN52021 by intra-abdominal injections. The random and chemotactic migration of polymorphonuclear leukocytes (PMNs) were measured by the agarose method. The backs of all guinea pigs were given intradermal injections of PAF and the numbers of the infiltration of inflammatory cells into the skin were determined. RESULTS: MTX inhibited random migration and chemotactic migration of PMNs to PAF, LTB4 and PAF-induced intraepidermal accumulation of inflammatory cells in dose- and time-dependent fashion. BN52021 specially inhibited PAF-induced chemotaxis of PMNs and intraepidermal accumulation of inflammatory cells, but did not inhibit PMNs random migration and LTB4-induced chemotaxis of PMNs. CONCLUSIONS: The inhibition of PMNs activities may be part of the mechanism of MTX therapy for psoriasis; BN52021 is a selective inhibitor of PAF-induced chemotaxis of PMNs, and therefore can be useful in the treatment of some inflammatory dermatoses such as psoriasis.

Animals↗
PubMed1996

[Determination of platelet activating factor and platelet associated IgG in pregnancy-induced hypertension].

OBJECTIVE: To determine the levels of platelet activating factor (PAF) and platelet associated IgG (PAIgG) in pregnancy-induced hypertension (PIH). METHODS: Twenty-eight cases of normal pregnant women and 44 cases of PIH (moderate, n = 23; severe, n = 21) were enrolled in this study. The plasma level of PAF was measured using platelet aggregation bioassay, and determination of PAIgG was performed by ABC-ELISA (enzyme-labeled immunosorbent assay) method. RESULTS: The level of plasma PAF in PIH patients (5.02 +/- 1.93 micrograms/L) was significantly higher than that in the controls (1.16 +/- 0.22 micrograms/L, P < 0.01). There was no difference between the levels of PAF in moderate PIH and severe ones. The level of PAIgG in PIH (6.3 +/- 4.9 micrograms/10(2)) was significantly higher than that in the control (3.8 + 1.8 micrograms/10(2), P < 0.05). CONCLUSIONS: PAF may be involved and play an important role in the pathophysiological changes in PIH. Autoimmunological reaction of platelets may exist in pregnant women with PIH.

Adult↗
PubMed1996

[The role of platelet-derived growth factor and ras P21 in experimental hepatocarcinogenesis].

In order to explore whether platelet-derived growth factor (PDGF) is involved in hepatocarcinogenesis, expression of PDGF-beta chain and ras P21 were investigated using immunohistochemical method in hepatocarcinoma induced with diethylnitrosamine (DENA). Elevated PDGF-beta chain and P21 protein levels were found in hepatocytes in the early stages after DENA administration. Along with the progression of hepatocarcinogenesis, immunopositive cells were increased with the formation of various foci and nodules and the staining was usually stronger in the peripheral parts of nodules. In addition, PDGF-beta and P21 often expressed simultaneously in the smae lesions, where the cells were also positive for AFP expression. The results suggest that abnormal expression of PDGF might be an early specific event during hepatocarcinogenesis and might be involved in the malignant transformation of the hepatocytes by autocrine as well through ras P21 signal pathways.

Animals↗
PubMed1996

[Comparison of diet, physical activity and serum lipids between Chinese and Japanese: Chengdu-Fukuoka Study].

A detailed diet history was taken from 326 Chinese adults, 116 college students in Chengdu, China, and 300 Japanese adults and 4529 college students in Fukuoka, Japan. Both populations consume high carbohydrate and low fat diet, but the Chinese diet was higher in carbohydrate, cereal energy/total energy ratio and polyunsaturated fatty acids/saturated fatty acids ratio, and lower in protein, fat and animal fat/total fat ratio compared to the Japanese diet. Cholesterol intake was significantly lower in Chinese than in Japanese (P < 0.001). Physical activity index in Chinese was higher than that in Japanese. Serum lipids and lipoprotein cholesterols were measured in the adults of Chinese and Japanese. Except the serum triglycerids level in female, the total cholesterol, TG, high density lipoprotein-cholesterol and low density lipoprotein-cholesterol levels in Chinese adults were lower than those in Japanese adults (P < 0.001). Since cholesterol is the major predisposing factor for coronary heart disease and the results of our study show that a high carbohydrate and low fat diet can be effective in lowering the cholesterol level in blood it will be of interest to see which kind of oriental dietary may be a preventive against coronary heart disease.

Adult↗