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Biomedical subjects

Z Bao

Publications and source records attributed to Z Bao.

At least 37 records · Page 2Linked to original sources
PubMed1999

Acetone catabolism by cytochrome P450 2E1: studies with CYP2E1-null mice.

Previous experiments in vitro have suggested that cytochrome P450 2E1 (CYP2E1) is involved in acetone catabolism by converting acetone to acetol and then to methylglyoxal, both intermediates in the gluconeogenic pathway. In the present study, CYP2E1-null mice were used to demonstrate the role of CYP2E1 in acetone catabolism in vivo. The blood acetone level in male CYP2E1-null mice was 3.3 +/- 0.9 microg/mL, which was similar to levels of their sex- and age-matched parental lineage strains C57BL/6N (2.3 +/- 0.2 microg/mL) and 129/Sv (3.5 +/- 0.3 microg/mL) mice (both are CYP2E1 wild-type). After fasting for 48 hr, the blood acetone levels in the CYP2E1 wild-type mice were increased by 2.5- to 4.4-fold, but that in the CYP2E1-null mice increased 28-fold. These results clearly demonstrate that CYP2E1 plays a vital role in the catabolism of acetone under fasting conditions.

Acetone↗
PubMed1999

Metabolism of methyl tert-butyl ether and other gasoline ethers in mouse liver microsomes lacking cytochrome P450 2E1.

To reduce the production of pollutants in motor vehicle exhaust, methyl tert-butyl ether (MTBE) and other ethers such as ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) are added to gasoline as oxygenates for more complete combustion. Metabolism of these gasoline ethers is catalyzed by cytochrome P450 (P450) enzymes. P450 2E1, which metabolizes diethyl ether, was suggested to be an enzyme involved. The present study used 2E1 knock-out mice (2E1-/-) to assess the contribution of 2E1 to the metabolism of MTBE, ETBE and TAME. Liver microsomes prepared from the 2E1 knock-out mice lacked 2E1 activity (assayed as N-nitrosodimethylamine demethylation), but were still active in metabolizing all three gasoline ethers. The levels of ether-metabolizing activity (nmol/min per mg) in the liver microsomes from 7 week old female 2E1 knock-out mice were 0.54+/-0.17 for MTBE, 0.51+/-0.24 for ETBE and 1.14+/-0.25 for TAME at a 1 mM substrate concentration. These activity levels were not significantly different from those of the sex- and age-matched C57BL/6N and 129/Sv mice, which are the parental lineage strains of the 2E1 knock-out mice and are both 2E1+/+. Our results clearly demonstrate that 2E1 plays a negligible role in the metabolism of MTBE, ETBE and TAME in mouse livers.

Aging↗
PubMed1999

Phosphorylated form of MacMARCKS is essential to LFA-1-dependent cell-cell adhesion of U937 monocytic cells.

MacMARCKS (MRP, F52), a protein kinase C (PKC) substrate, is involved in the activation of beta2-integrin. To determine the role of the PKC-mediated phosphorylation of MacMARCKS in this process, human U937 monocytic cells were transfected with cDNAs encoding wild type or mutant MacMARCKS. We observed that the expression of the exogenous wild type MacMARCKS greatly enhanced LFA-1-mediated cell-cell adhesion in U937 cells treated with phorbol 12-myristate 13-acetate (PMA). This MacMARCKS-stimulated adhesion depended on the phosphorylation status of MacMARCKS: whereas phosphorylated MacMARCKS enhanced adhesion, unphosphorylated MacMARCKS inhibited it. However, phosphorylated MacMARCKS alone could not induce LFA-1-mediated cell-cell adhesion unless phorbol esters were added, suggesting that the phosphorylation of other proteins might also be involved. Okadaic acid, a phosphatase inhibitor, induced LFA-1-mediated cell-cell adhesion only in the cells expressing wild type or phosphorylated MacMARCKS and not in the cells expressing unphosphorylated MacMARCKS. Therefore, we conclude that the phosphorylated form of MacMARCKS is essential to LFA-1-mediated cell-cell adhesion.

Animals↗
PubMed1999

[Quality evaluation of locally-prepared kits for HIV antibody detection in clinical applications].

OBJECTIVE: To evaluate the quality of eight kinds of locally prepared enzyme-linked immunosorbent assay (ELISA) kits for HIV antibody (anti-HIV) detection and study their current status in clinical applications. METHODS: Two hundred serum specimens were tested with eight kinds of locally prepared ELISA kits for anti-HIV screening, with an imported kit as reference, including 100 specimens with confirmed positive, negative or undetermined anti-HIV and 100 specimens collected from the drug abusers in Xinjiang Region. RESULTS: Anti-HIV could be detected in all the 74 confirmed positive specimens with the imported reference kit, with sensitivity of 100%. But, six to eighteen specimens were false negative detected with local prepared kits, with sensitivities of 81.1%-91.9%, mainly in those collected from the drug abusers with weak positive for anti-HIV. Two of the 107 confirmed negative specimens were false positive by the imported reference kit, with a specificity of 98.2%, and 0-8 specimens were false positive by locally prepared kits, with specificities of 92.5%-100%. CONCLUSION: The sensitivity of locally prepared ELISA kits for anti-HIV screening should be improved further to ensure the safety of blood transfusion and the control of AIDS/HIV.

China↗
PubMed1999

[Effects of kidney nourishing and spleen invigorating recipes on glucocorticoid receptors of pulmonary tissue and plasma corticosterone in asthmatic rats].

OBJECTIVE: To observe the effects of Guiqi San (GQS, a Chinese herbal preparation with effect of Kidney Nourishing and Spleen Invigorating), Bushen Dingchuan Tang (BSDCT, with effects of Kidney Nourishing) and Liujunzi Tang (LJZT, with effect of Spleen Invigorating) on glucocorticoid receptor (GCR) and plasma corticosterone (PCC) in asthmatic rats. METHODS: The asthmatic model of rats made by intraperitoneal injection of ovalbumin two weeks before, and the asthma consecutively challenged daily with spray inhalation of 1% ovalbumin for 7 days. The asthmatic rat treated with above-mentioned three recipes (per os) and Beclomethasone dipropionate (BDP) were taken as treated groups and the asthmatic rat as control group. GCR density of the pulmonary tissue and PCC were determined by radioligand-binding assay and competitive protein radio-binding assay. RESULTS: The RT value of GCR reduced gradually and PCC lowered also after asthma being developed. On day 7th, the three recipes could markedly up-regulate the RT of GCR and PCC. There was significant difference statistically as compared the pulmonary tissue GCR density and PCC of GQS (P < 0.01, P < 0.05), BSDCT (P < 0.05, P < 0.05) and LJZT (P < 0.05, P < 0.05) groups with those of control (asthmatic group) on the 7th day. CONCLUSION: GQS, BSDCT and LJZT played an up-regulate role of GCR density and improvement of adrenocortical function in asthmatic rats in the management of asthma attacks.

Animals↗
PubMed1998

[Studies on extensive application of bromoacetamide in various types of schistosomiasis endemic area].

AIM: To provide scientific basis for the popularization and application of molluscide bromoacetamide. METHODS: Large scale application of bromoacetamide in twenty eight counties of four provinces was investigated and its molluscicidal effect in marshland and influence on marshland grass (Cyperus) and fishes were observed. RESULTS: High molluscicidal effect of bromoacetamide was found against both snails and snail eggs in various environments. According to the results observed in different fields, the applicable dosage of bromoacetamide is 1.5-2 g/m2 for spraying method, 1.5-2 g/m3 for immersing method and 1.5-2 g/m for immersing in combination with shovelling the turf along the bank. When it was applied in fish-raising ponds or rivers at an applicable dosage, no toxic effect on fishes was found. The spraying dosage of bromoacetamide did not affect the rice seedling but it did some damage to the leaf-tips of marshland grass, however, the grass did turn green and grow. CONCLUSION: Bromoacetamide has proved to be a safe and effective mulluscicde against Oncomelania under various field conditions.

Acetamides↗
PubMed1997

[Application of serum bile acid chromatography to the diagnoses of liver diseases].

In order to explore the specificity of serum bile acid (SBA) chromatograph in the diagnoses of different kinds of hepatosis, we investigated by means of gas chromatography the changes of serum bile acids in workers who exposed to hexogen or chloroethylene and in patients who suffered from hepatosis such as acute jaundice hepatitis, chronic active hepatitis, cirrhosis and liver cancer. The results revealed different disturbances of SBA occurring in the liver injuries induced by the two kinds of hepatotoxicant. Serum lithocholic acid (LCA), deoxycholic acid (DCA) and chenodeoxycholic acid (CDCA) in workers exposed to hexogen and wre significantly different from those of the control group respectively (P < 0.01, P < 0.01, P < 0.05); on the other hand, only serum LCA and DCA went up in workers exposed to chloroethylene (P < 0.0005, P < 0.001). The main changes both concentrated on the secondary bile acids. In acute jaundice hepatitis, chronic active hepatitis, cirrhosis and liver cancer, serum LCA, DCA, CDCA and cholic acids (CA) all went up in different degrees compared with the control group respectively (P < 0.005, P < 0.025, P < 0.005, P < 0.005). But no difference was noted among the 4 kinds of bile acids (P > 0.5), except that between CA and CDCA. These provided the evidence of the diagnosis and identification of clinical hepato-biliary diseases and occupational liver injures.

Cholic Acids↗
PubMed1996

Role of MacMARCKS in integrin-dependent macrophage spreading and tyrosine phosphorylation of paxillin.

The cellular function of the MARCKS family of protein kinase C substrates is unknown. In this report, we present evidence that indicates a role for MacMARCKS, a member of the MARCKS family, in the integrin-dependent signal transduction pathways in macrophages. Using a dominant negative mutant of MacMARCKS, we showed that MacMARCKS participates in several integrin-dependent macrophage functions, including the phorbol ester-stimulated macrophage spreading, a process involving multiple integrins. The dominant negative mutant also blocks macrophage spreading on immune complex-coated surfaces, a process again requiring beta2 integrin. More direct evidence of the role of MacMARCKS in the integrin-dependent pathway is the ablation of macrophage binding to complement iC3b-coated sheep erythrocytes by MacMARCKS mutant, suggesting an effect of this mutant on the avidity of complement receptor 3, a member of the beta2 integrin family. To further evaluate the possible mechanism of MacMARCKS function, the integrin-dependent tyrosine phosphorylation of paxillin was examined. Concomitant with the inhibition of macrophage spreading and rosette formation, MacMARCKS mutant also inhibits integrin-dependent tyrosine phosphorylation of paxillin. Furthermore, immunofluorescent microscopy data showed that MacMARCKS and paxillin colocalize in the membrane ruffles at the leading edge of the spreading cells, providing a potential site and opportunity for MacMARCKS to participate in the regulation of integrin-dependent tyrosine phosphorylation of paxillin. Together, these data strongly suggest that MacMARCKS plays a role in integrin-dependent signal transduction pathways in macrophages.

Amino Acid Sequence↗
PubMed1996

Stereoselective nucleophilic substitution of oxazepam and racemization in acidic methanol and ethanol.

Enantiomeric and racemic oxazepam (OX), 3-O-methyloxazepam (MeOX), and 3-O-ethyloxazepam (EtOX) were used to study racemization, heteronucleophilic, and homonucleophilic substitution reactions in anhydrous acidic methanol and ethanol. Kinetics of racemization and nucleophilic substitution reactions in nondeuterated and deuterated solvents were determined by circular dichroism spectropolarimetry, chiral stationary phase high-performance liquid chromatography (HPLC), reversed-phase HPLC, and mass spectrometry. Several reactions occurred when (S)-OX, for example, was dissolved in acidic methanol: (1) (S)-OX itself underwent spontaneous racemization, (2) the 3-hydroxyl group of (S)-OX was stereoselectively substituted by the methoxy group of methanol to form MeOX enriched in (S)-MeOX, and (3) the 3-methoxy group of (R)-MeOX was stereoselectively substituted by the methoxy group of methanol to form MeOX enriched in (S)-MeOX, and (4) the 3-methoxy group of (R)-MeOX was stereoselectively substituted by the methoxy group of methanol to form MeOX enriched in (R)-MeOX. Repetitive reactions 3 and 4 eventually resulted in a racemic MeOX. Similar reactions occurred for an enantiomeric OX in acidic ethanol.

Anti-Anxiety Agents↗
PubMed1996

2-(methylamino)-5-chlorobenzophenone imine: a novel product formed in base-catalyzed hydrolysis of diazepam.

Diazepam (1), a hypnotic and anxiolytic drug in worldwide use, formed an intermediate product in a mixture of ethanol and sodium hydroxide ([NaOH] > or = 1 M). The intermediate product slowly decomposed to form 2-(methylamino)-5-chlorobenzophenone imine (2) and 2-(methylamino)-5-chlorobenzophenone (3). The amount of 2 formed, relative to that of 3, increased with increasing NaOH concentration. Compound 2, a heretofore unknown derivative of 1, was characterized by high-performance liquid chromatography, ultraviolet-visible absorption, mass, and proton nuclear magnetic resonance spectral analyses.

Benzophenones↗
PubMed1996

[Human melanoma-specific peptide antigens recognized by HLA-A2 restricted tumor-infiltrating lymphocytes].

OBJECTIVE: HLA-A2-associated peptides were extracted from human melanoma cell lines and used to study human melanoma-specific peptide antigens for HLA-A2-restricted tumor-infiltrating lymphocyte (TIL). METHODS: TILS were derived from the peripheral lymph nodes of HLA-A2+ human melanoma patients, HLA-A2 molecules were purified from the melanoma cell lines by immunoaffinity column chromatography of detergent-solubilized cell pellets. Peptides bound to the HLA-A2 molecules were acid eluted and fractionated by reversed phase RP-HPLC. Individual fractions were assessed for their ability to reconstitute melanoma-specific epitopes by adding to the HLA-A2+ Ag-processing mutant cell, T2. RESULTS: These TIL lysed HLA-A2+ autologous and allogeneic melanomas, but not the HLA-A2- melanomas. They also did not lyse the HLA-A2+ non-melanoma cell lines. The RP-HPLC separations of reconstituting fractions revealed three peaks (fractions) of reconstitution. CONCLUSION: These results showed that peptides derived from three active fractions were related to human melanoma-specific peptide antigens recognized by HLA-A2-restricted TIL.

Antigens, Neoplasm↗
PubMed1995

MacMARCKS mutation blocks macrophage phagocytosis of zymosan.

A major protein kinase C substrate, MacMARCKS (F52, MPR), was examined for its role in phagocytosis. In macrophage-phagocytosing zymosan particles, MacMARCKS was concentrated around nascent phagosomes as detected by immunofluorescent microscopy. The effector domain of MacMARCKS contains the phosphorylation sites, a calmodulin binding site, as well as a putative actin binding site. Stable J774 macrophage cell lines constitutively expressing effector domain deletion mutants of MacMARCKS were generated. When given zymosan particles, these transfectants showed approximately a 90% reduction in their phagocytic capacity. The receptor-mediated endocytosis of acetylated low density lipoproteins, however, was not affected by the mutant. These results strongly suggest the involvement of MacMARCKS in macrophage phagocytosis.

Cell Adhesion Molecules↗
PubMed1994

A general method for facilitating heterodimeric pairing between two proteins: application to expression of alpha and beta T-cell receptor extracellular segments.

Generation of soluble T-cell receptor (TCR) molecules by a variety of genetic engineering methods has been hampered by inefficient pairing of alpha and beta subunits in the absence of their respective transmembrane regions and associated CD3 components. To overcome this obstacle, we have added 30-amino acid-long segments to the carboxyl termini of alpha and beta extracellular domains via a cleavable flexible linker. These peptide segments (BASE-p1 for alpha and ACID-p1 for beta) have been previously shown to selectively associate to form a stable heterodimeric coiled coil termed a leucine zipper. Homodimeric structures are not permitted due to electrostatic repulsion among amino acid side chains. Expression of a representative TCR-leucine zipper fusion protein in a baculovirus expression system results in production of alpha beta TCR heterodimer at 0.6-1.4 mg/liter. This yield is 5- to 10-fold greater than that of the TCR expressed in the absence of the synthetic leucine zipper sequence. The structure of the TCR component of the fusion heterodimer was judged to be native when probed with a panel of 17 mAbs specific for alpha and beta constant and variable domains. A mAb specific for the isolated BASE-p1/ACID-p1 coiled coil was also generated and shown to react with the TCR fusion protein. The above technology should be broadly useful in the efficient production and purification of TCRs as well as other heterodimeric proteins.

Amino Acid Sequence↗
PubMed1987

Reversed-phase high-performance liquid chromatographic separation of phenolic derivatives of benzo[a]pyrene, benz[a]anthracene, and chrysene with monomeric and polymeric C18 columns.

The separation of monohydroxylated derivatives (phenols) of benzo[a]pyrene, benz[a]anthracene, and chrysene was studied by reversed-phase high-performance liquid chromatography using a monomeric Zorbax ODS column and a polymeric Vydac C18 column. The Vydac C18 column resolved the phenols of each hydrocarbon with a wide range of retention times than the Zorbax ODS column. Four K-region phenols of benzo[a]pyrene are either not separated or marginally separated on both monomeric and polymeric columns. Other K-region and non-K-region phenols of all three hydrocarbons can be separated by using the monomeric and polymeric columns in combination.

Animals↗