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Biomedical subjects

Y Huang

Publications and source records attributed to Y Huang.

At least 883 records · Page 49Linked to original sources
PubMed1996

Expression and zonal distribution of CYP2D16 in the guinea pig adrenal cortex: relationship to xenobiotic metabolism.

We recently cloned a CYP2D subfamily member (CYP2D16) from a guinea pig adrenal cDNA library and investigated the expression of CYP2D16 in the guinea pig adrenal cortex and its relationship to adrenal xenobiotic metabolism. A modified sodium dodecyl sulfate-polyacrylamide gel electrophoresis technique revealed three major bands in the molecular mass range of cytochromes P450 in guinea pig adrenal microsomes. Two of the bands were immunoreactive with anti-CYP17 (54 kDa) or anti-CYP21 (52 kDa) antibody. The third band (50 kDa) was immunoreactive with antibody raised against CYP2D1 and with anti-CYP1A1/1A2 antibody. Microsequencing of the 50-kDa band yielded an amino-terminal sequence of 38 amino acids identical to that deducted from the CYP2D16 cDNA. In addition, Northern blot analyses indicated the CYP1A1 was not expressed in the adrenal gland, suggesting that only CYP2D16 composed the microsomal 50-kDa band. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analyses demonstrated greater expression of CYP2D16 in microsomes from the inner zone (zona reticularis) of the adrenal cortex than from the outer zones, coinciding with the major site of adrenal xenobiotic metabolism. Bufuralol-1'-hydroxylase activity, a marker for CYP2D isozymes, was also greater in inner- than in outer-zone microsomal preparations and was highly correlated with CYP2D16concentrations. Northern blot analysis with a full-length CYP2D16 cDNA as the probe gave strong bands with adrenal inner zone RNA preparations and relatively weak bands with outer zone RNA. CYP2D16 mRNA was also detectable in liver and kidney RNA preparations, but at lower levels than in the adrenal inner zone, and it was not detectable in testes, lung, intestines, or heart. Overall, the results demonstrate that CYP2D16 is expressed at highest levels in the inner zone of the guinea pig adrenal cortex and suggest a major role for this isozyme in adrenal xenobiotic metabolism.

Amino Acid Sequence↗
PubMed1996

Efficacy of disinfectants against biofilm cells of methicillin-resistant Staphylococcus aureus.

The effect of disinfectants on biofilm cells of methicillin-resistant Staphylococcus aureus (MRSA) was evaluated. Eradication of biofilm cells of MRSA by chlorhexidine gluconate, benzalkonium chloride, alkyldiaminoethyl glycine and sodium hypochlorite required a much longer time than that of planktonic cells in suspensions. Benzalkonium chloride (0.1%) and alkyldiaminoethyl glycine (0.1%) were ineffective for eradication of biofilm cells even after 1 h, but were effective for eradication of planktonic cells within 20 s. Sodium hypochlorite (0.01%) was also ineffective for eradication of biofilm cells even after 30 min, but was lethal to planktonic cells within 20 s.

Biofilms↗
PubMed1996

Bcl-xL overexpression inhibits taxol-induced Yama protease activity and apoptosis.

Intracellularly, the anticancer drug taxol induces tubulin polymerization and mitotic arrest, followed by apoptosis. The DNA repair enzyme poly(ADP-ribose) polymerase (PARP) and lamins are known to be degraded during apoptosis. PARP is a substrate for the Yama protease, which is encoded by the CPP32 beta/ Yama gene, whereas lamins are degraded by the Yama and lamin proteases. In the present studies, we determined the effects of enforced overexpression of the antiapoptosis Bcl-xL protein on taxol-mediated microtubule and cell cycle perturbations, as well as on taxol-induced apoptosis and associated Yama protease activity in human myeloid leukemia HL-60 cells. Our data demonstrate that high Bcl-xL levels do not affect the microtubular bundling or mitotic arrest due to taxol but significantly inhibit the morphological, flow cytometric, and DNA fragmentation features associated with taxol-induced apoptosis. This resulted in a significant improvement in the survival of taxol-treated cells that possess high Bcl-xL levels. In the control HL-60 cells, following taxol treatment, whereas the mRNA of Yama was not induced, taxol-induced apoptosis was associated with Yama activation and PARP as well as lamin B1 degradation. These features were blocked by coculture of these cells with the cysteine protease inhibitor YVAD-cmk as well as in cells with overexpression of Bcl-xL. These results suggest that Bcl-xL antagonizes taxol-induced apoptosis by a mechanism that interferes with the activation of a key protease involved in the execution of apoptosis.

Apoptosis↗
PubMed1996

Intracellular metabolism of Ara-C and resulting DNA fragmentation and apoptosis of human AML HL-60 cells possessing disparate levels of Bcl-2 protein.

We examined the effects of high intracellular levels of Bcl-2 on the metabolism and DNA incorporation of high-dose Ara-C (HIDAC) as well as on Ara-C-induced DNA strand breaks and apoptosis of human AML HL-60 cells. HL-60/Bcl-2 and HL-60/neo cells were created by retrovirally transfecting the human AML HL-60 cells with the pZip-bcl-2 and pZip-neo plasmids, respectively. As compared to HL-60/neo, HL-60/Bcl-2 cells contained significantly higher (approximately 10-fold) p26Bcl-2, but equivalent levels of Bax and undetectable levels of Bcl-xL. HIDAC (10 or 100 microM for 4 h) produced the kilobase size and internucleosomal DNA fragmentation associated with apoptosis in HL-60/neo but not in HL-60/Bcl-2 cells. Significantly greater loss of survival (by MTT assay) and flowcytometric and morphologically recognizable apoptosis were observed in HL-60/neo cells. HIDAC did not affect Bcl-2 levels in either cell type. The intracellular accumulation of Ara-CTP relative to dCTP, Ara-C DNA incorporation and Ara-C-induced early DNA damage in the form of strand breaks (detected by alkaline elution assay) were not significantly different between HL-60/Bcl-2 and HL-60/neo cells. In addition, HIDAC treatment caused similar DNA synthesis inhibition in the two cell types. These results indicate that high intracellular levels of Bcl-2 operate distally to inhibit the final apototic cell death pathway by preventing the conversion of HIDAC-induced early DNA damage into lethal DNA fragmentation associated with apoptosis.

Antimetabolites, Antineoplastic↗
PubMed1996

Separate activation of intracellular Ca2+ release, voltage-dependent and receptor-operated Ca2+ channels in the rat aorta.

Both intracellular Ca2+ release and Ca2+ influx through plasma membrane channels contribute jointly to the elevation of cytoplasmic Ca2+ levels which regulate the contractility of vascular smooth muscle in response to vasoconstrictors. The objective of the present study was to design new protocols to experimentally separate three Ca(2+)-elevating pathways involved in the noradrenaline-induced contractile response, intracellular Ca2+ release, Ca2+ influx through the voltage-dependent (VDCCs) and the receptor-operated (ROCCs) Ca2+ channels with Ca2+ channel blockers in the isolated rat aortic rings. VDCCs were simply activated by membrane depolarization with 60 mM K+ solution and Ca2+ release from internal stores was reflected by the noradrenaline-induced contraction in Ca(2+)-free, high K4 solution. Nifedipine, diltiazem and verapamil concentration-dependently inhibited VDCCs and intracellular Ca2+ release with high affinity. ROCCs were activated by the following procedures: the noradrenaline-induced contractile response due to intracellular Ca2+ release was fully reversed by nifedipine at 100 nM, diltiazem at 3 microM and verapamil at 10 microM, the concentration of each drug was 10-fold greater than that causing a complete inhibition of VDCCs. Under this condition, addition of 1 mM Ca2+ induced a second sustained contraction which was fully reversed by 0.3 microM prazosin. The second contractile response was most likely caused by Ca2+ influx through the noradrenaline-activated ROCCs. Higher concentrations of diltiazem and verapamil were needed to inhibit ROCCs, and nifedipine was without effect. The sensitivity order of Ca2+ channel blockers for three Ca(2+)-elevating pathways was the same: VDCCs > intracellular Ca2+ release > ROCCs. The present results indicate that VDCCs can be functionally separated from ROCCs with the experimental designs used in this study and noradrenaline evoked contractions of rat aorta by activating intracellular Ca2+ release and Ca2+ influx through VDCCs and ROCCs. However, Ca2+ influx via ROCCs makes a small contribution to the noradrenaline-induced contractile response.

Animals↗
PubMed1996

Quantitative assessment of the cataractogenic potential of very low doses of neutrons.

We report on the prevalence and relative biological effectiveness (RBE) for various stages of lens opacification in rats induced by very low doses (2 to 250 mGy) of medium-energy (440 keV) neutrons, compared to those for X rays. Neutron doses were delivered either in a single fraction or in four separate fractions and the irradiated animals were followed for over 100 weeks. At the highest observed dose (250 mGy) and at early observation times, there was evidence of an inverse dose-rate effect; i.e., a fractionated exposure was more potent than a single exposure. Neutron RBEs relative to X rays were estimated using a non-parametric technique. The results were only weakly dependent on time postirradiation. At 30 weeks, for example, 80% confidence intervals for the RBE of acutely delivered neutrons relative to X rays were 8-16 at 250 mGy, 10-20 at 50 mGy, 50-100 at 10 mGy and 250-500 at 2 mGy. The results are consistent with the estimated neutron RBEs in Japanese A-bomb survivors, though broad confidence bounds are present in the Japanese results. Our findings are also consistent with data reported earlier for cataractogenesis induced by heavy ions in rats, mice, and rabbits. We conclude from these results that, at very low doses (<10 mGy), the RBE for neutron-induced cataractogenesis is considerably larger than the RBE of 20 commonly used, and use of a significantly larger value for calculating equivalent dose would be prudent.

Animals↗
PubMed1996

Cultured human trabecular meshwork cells express functional alpha 2A adrenergic receptors.

PURPOSE: For the treatment of glaucoma, alpha-2 adrenergic receptor (alpha 2-AR) agonists are thought to lower intraocular pressure primarily by decreasing aqueous humor production. Effects on the outflow pathways, however, also may occur. To begin to examine this possibility, the authors characterized the alpha 2-AR subtypes present in cultures of human trabecular meshwork (HTM) cells using both immunofluorescence microscopy and functional measures of alpha 2-AR activation. METHODS: For immunofluorescence microscopy, subtype-specific polyclonal antibodies that recognize each of the human alpha 2-AR subtypes (alpha 2A, alpha 2B, alpha 2C) were used. Functional studies involved the inhibition of forskolin-stimulated cyclic adenosine monophosphate (cAMP) production, the stimulation of mitogen-activated protein (MAP) kinase activity, and the stimulation of mitotic activity as reflected by the expression of proliferating cell nuclear antigen (PCNA). RESULTS: From the immunofluorescence microscopy, there was evidence for the presence of the alpha 2A subtype, but not alpha 2B or alpha 2C subtype, on HTM cells. The administration of the alpha 2-agonist, dexmedetomidine, to HTM cells resulted in a 90% inhibition of forskolin-stimulated cAMP formation, a twofold stimulation of MAP kinase activity, and a threefold increase in the expression of PCNA. Additionally, preincubation of cells with either of the alpha 2-AR-selective antagonists, rauwolscine or atipamezole, reversed the functional effects of dexmedetomidine. CONCLUSIONS: Functional alpha 2A-ARs are present on HTM cells where they may affect the outflow pathway during the treatment of glaucoma with alpha 2-AR agonists.

Adrenergic alpha-Agonists↗
PubMed1996

Enforced expression of Bcl-XS induces differentiation and sensitizes chronic myelogenous leukemia-blast crisis K562 cells to 1-beta-D-arabinofuranosylcytosine-mediated differentiation and apoptosis.

Human chronic myelogenous leukemia-blast crisis K562 cells have been demonstrated to be relatively resistant to antileukemic drug-induced apoptosis. This has been attributed to the activity of p210bcr-abl tyrosine kinase present in the K562 cells, which is known to suppress drug-induced apoptosis. Recently, K562 cells have been shown to express the antiapoptosis Bcl-xL but not Bcl-2 proteins. To investigate the contribution of Bcl-xL toward resistance to drug-induced apoptosis, we created K562/Bcl-xS and K562/neo cells by electroporating the expression plasmids pSFFVneo-Bcl-xS and pSFFVneo, containing the bcl-xS and neomycin resistance genes, respectively, into K562 cells. K562/Bcl-xS but not K562/neo cells expressed the bcl-xS mRNA and p19Bcl-xS protein. In contrast, both cell types expressed equivalent levels of Bcl-xL, Bax, Bcl-2, Myc, retinoblastoma, p21cbor-abl, and p145abl proteins. A significant increase in the hemoglobin levels was observed in the K562/Bcl-xS compared with the K562/neo cells (P < 0.05). In addition, K562/Bcl-xS cells were significantly more sensitive than K562/neo cells to undergoing erythroid differentiation induced by low-dose 1-beta-D-arabinofuranosylcytosine (ara-C) and hexamethyl bisacetamide (P < 0.05), but not by all-trans-retinoic acid. Low-dose ara-C- or hexamethyl bisacetamide-induced differentiation was not associated with apoptosis of K562/Bcl-xS or K562/neo cells. Low-dose ara-C-induced erythroid differentiation was accompanied by conversion of the retinoblastoma protein to predominantly its underphosphorylated isoform as well as by down-regulation of Myc levels in K562/Bcl-xS and K562/neo cells. Importantly, exposure to high-dose ara-C (HIDAC; 100 microM ara-C for 4 h) caused internucleosomal DNA fragmentation and the morphological features of apoptosis in K562/Bcl-xS cells. These effects were modestly enhanced by cotreatment with HIDAC plus herbimycin A. In contrast, K562/neo cells were completely resistant to HIDAC- and herbimycin A-induced apoptosis. These results indicate that the expression of Bcl-xS induces erythroid differentiation and partially sensitizes chronic myelogenous leukemia-blast crisis-derived K562 cells to ara-C-induced differentiation and apoptosis.

Antimetabolites, Antineoplastic↗
PubMed1996

Anti-inflammatory activity of 2,3-dihydrophthalazine-1,4-diones in CF1 mice.

2,3-Dihydrophthalazine-1,4-diones were observed to be potent anti-inflammatory agents as well as capable of protecting against endotoxin shock in mice at 8 mg/kg i.p. These agents blocked both locally- and centrally-induced pain at 8 mg/kg i.p. In part they appear to mediate their effects due to their ability to suppress the release of cytokines such as TNF alpha and IL-1 from macrophages, as well as the binding of these cytokines to high-affinity receptors on target cells involved in the inflammation process. Lysosomal hydrolytic enzymes as well as 5'-lipoxygenase activities were reduced by the agents.

Analgesics↗
PubMed1996

Stable expression of anti-HPV 16 E7-ribozyme in CV-1 cell lines.

The HPV16 (human papilloma virus type 16) E7 gene product, an oncoprotein, has been considered to be involved in the pathogenesis of anogenital cancer, particularly of cervical cancer. In order to evaluate the effect of suppression of the expression of the E7 gene in CV-1 cells by ribozyme, Rz523 with a transacting ribozyme targeted to the E7 RNA and two processing ribozyme genes at the 5' and 3' flank was cloned into the eukaryotic expression plasmid pREP9 under the control of RSV-LTR promoter. The resultant plasmid pRSV-Rz523 was transfected into CV-1 cells by calcium phosphate coprecipitation. The expression of the ribozyme in G418-resistant cells was detected by dot-blot hybridization. Ribozymes stably expressed in the CV-1 cells were at a level of 9.0 pmol per 10(6) cells, in which the active ribozyme molecules were more than 50 fmol per 10(6) cells. The result of RNase protection assay showed that the steady-state level of the E7 RNA fragment in CV-1 cell lines was significantly reduced by about 90% in ribozyme-expressing cells. In contrast, the antisense control plasmid pRSV-AE7 only exhibited about 20%. This result implicated the possibility of reversing the malignant phenotype of cervical cancer by means of suppressing the expression of the E7 gene with ribozyme.

Cell Line↗
PubMed1996

[Rapid prenatal diagnosis of 60 cases with beta-thalassemia by reverse dot blot analysis].

OBJECTIVE: To evaluate the rapid prenatal diagnosis method for beta-thalassemia by reverse dot blot (RDB) analysis. METHODS: Using RDB analysis which can detect 18 types of beta-thalassemia mutation, 60 fetuses (with 1 twin) suspected of beta-thalassemia from 59 couples in Southern China were investigated. RESULTS: 15 fetus had normal genotype, 34 were carriers of heterozygous with one of parental affected gene; 10 had both parental affected genes-heterozygous or homozygous; and 1 was not able to identified. Three rare types of beta-thalassemia mutations (CD43, CD14-15, CD27-28) were detected. CONCLUSIONS: The RDB assay is able to complete the screening of beta-thalassemia mutation by DNA hybridization in only one single working day. It is simple, accurate and convenient to operate without radio-isotopes. It can be used as a routine technique in clinical laboratory for the detection of carriers and prenatal diagnosis of beta-thalassemia.

Adult↗
PubMed1996

[Alteration of mRNA transcripts of rat Sertoli cell secreted proteins and Leydig cell LH/CG-R protein following glycosides of Tripterigium Wilfordii Hook administration].

Our studies were undertaken to assess the male antifertility mechanism of the total glycosides extracted from Tripterigium Wilfordii Hook. f. (GTW). In experimental group I, GTW was given by gastric gavage at a dose of 30 mg/kg per day for 35 days. In experimental group I, GTW was given in the same way at a dose of 10 mg/kg per day for 49 days. The transcripts level analysis indicated that in all the experimental groups ABP, SGP-2 and LH/CG-R mRNA were increased. Two ABP and two LH/CG-R mRNA transcripts with respective molecular sizes of 1.7 kb, 2.3 kb and 1.2 kb, 4.4 kb were identified. ABP and LH/ CG-R mRNA with 1.7 kb and 1.2 kb increased, while those with 2.3 and 4.4 kb remained unchanged. In addition, the changes of different proteins at the mRNA level were shown to be GTW dose-dependent. The morphological features of germ cell degeneration and appearance of germ cells in tubular lumen suggest that the increases in transcripts level of three proteins in testis may not be directly associated with the effect of GTW. The question whether GTW interfere with the function of sertoli cells and leydig cells would be study.

Androgen-Binding Protein↗
PubMed1996

[Carcinogenic mechanisms of multiple genes in cervical carcinoma].

The alterations of multiple genes and their carcinogenic mechanism in cervical carcinoma were studies by molecular hybridisation, PCR and PCR-ASO techniques. The G-T point mutation in the 12th coden of Ha-ras was detected in cervical carcinomas with mutation frequency of 18.2% (8/44), and the amplification rate of Ha-ras gene was 45% (9/20). The c-erb B2 was amplified 3-30 fold with an amplification rate of 73.3% (11/15) in cervical carcinomas and 5 cancerous samples showed gene rearrangement. The elevated copies of c-myc gene with amplification rate of 91.7% (11/12) were observed in cervical carcinomas. The study of HPV16 viral gene showed that the existence of HPV16 DNA sequence was positively associated with c-myc gene amplification in cervical cancerous samples. The p53 and Rb tumor suppressor genes absence of deletion were observed in the 12 specimens of cervical carcinoma investigated. As mentioned above, the study on alteration and carcinogenic mechanism of multiple genes indicated that 3 oncogenes and HPV16 viral gene were activated or integrated throygh different mechanisms and they played roles in co-carcinogenesis. The integration of HPV16 gene might promote the c-myc gene at the early stage in carcinogenesis of cervical carcinoma, while the alteration of Ha-ras and c-erb B2 gene might be middle-late event. As for the roles of the p53 and Rb tumor suppresor gene in cervical carcinogenesis need further researches.

Carcinoma, Squamous Cell↗
PubMed1996

[The immuno-pathological damage of placenta and its types in pregnancy induced hypertension].

OBJECTIVE: To study the immuno-pathological damage to placenta and its types in pregnancy induced hypertension (PIH). METHODS: Using immunohistochemical technique (PAP method), authors studied the expression and localization of IgG, IgE, C3, C4, 5-HT on the villous vessels wall in PIH patients (n = 22) and normal pregnant women (n = 10), and observed the pathological changes of placenta with mast cell and connective tissue stain. RESULTS: The immunostaining of IgG, IgE, C3, C4, and 5-HT were seen in the wall of villous vessels in PIH patients, the strong positive rate were 100%, 90%, 100%, 100%, 90% in severe PIH patients respectively, accompanied by aggregation of mast cells and lesions of villi and villous arterioles. CONCLUSION: The immunological compound reaction and types 1, N of anaphylactic reactions took place in the placenta of PIH patients. It showed that the immunological factors were closely related to PIH.

Antigen-Antibody Complex↗