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H X Yu

Publications and source records attributed to H X Yu.

13 recordsLinked to original sources
PubMed2005

Three-dimensional quantitative structure activity relationship (3D-QSAR) analysis for in vitro toxicity of chlorophenols to HepG2 cells.

In the present paper, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were applied to investigate two 3D-QSAR models for the cytotoxicity of chlorophenols. These models have evaluated the intensity of chlorophenols' toxicity on HepG2 cells in vitro. The CoMFA model has both high consistency and predictability. The contribution of the electrostatic field to biological activity is greater than that of the steric field. The CoMSIA model used in this study includes two fields, one is hydrophobic field, and the other is electrostatic field. The relative contribution of them is 0.789:0.211. Consisted with the CoMFA model, the CoMSIA electrostatic filed also plays a dominant role. The CoMFA and CoMSIA contour maps significantly elucidated that the electrostatic field is more important than the other fields and might be one of the reasons resulting in potential reactive mechanism involved in cell proliferation inhibition.

Cell Line, Tumor↗
PubMed2005

A11 Tetramer-assisted characterization of Rta-specific CD8+ T-cell responses in healthy virus carriers.

HLA Class I-restricted CD8(+) T-cell responses are believed to play an important role in controlling Epstein-Barr virus (EBV) infection, which has been consistently associated with nasopharyngeal carcinoma (NPC). Immediate early transactivator Rta of EBV has been shown to be associated with the reactivation of EBV from latency and drive the lytic cascade of EBV and comprise an important target for EBV-specific cellular cytotoxicity. Furthermore, BRLF1 is specifically expressed in NPC tumor cells. The protein product of BRLF1, Rta, could then be considered as a NPC tumor antigen. Therefore, cellular immunity against Rta represents a very important part of the immunity against NPC, as they should prevent the replication of EBV. In the present study, Rta-specific CD8(+) T-cell responses in healthy virus carriers were characterized by using A1101 tetramer containing the known Rta epitope ATIGTAMYK (134-142). We clearly showed A1101/ATIGTAMYK tetramer-reactive CD8(+) T cells in the circulation of healthy virus carriers, ranging from 2.13 to 9.03%. We then studied the expression of perforin and interferon-gamma (IFN-gamma) secretion in these Rta-specific T cells. Our study demonstrated that Rta-specific T cells are capable of IFN-gamma production and nearly 90% of the Rta-specific CD8(+) T cells expressed perforin. Presumably, these are the cells that play an important role in determining the initiation of the lytic cycle or the clearance of EBV.

Antigens, Neoplasm↗
PubMed2003

Associations of HLA microsatellites with rheumatoid arthritis in Singaporean Chinese.

Rheumatoid arthritis in Singaporean Chinese has previously been shown to be associated with the DRB1*0405, DRB1*1001 haplotypes and to the DRB1*0901 haplotype when the former two were removed. The present paper focused on eight HLA associated microsatellite markers (TNFa, TNFd, D6S273, TAP1CA, DQCAR, DQCARII, D6S2222, D6S2223) and their allelic associations with Chinese RA. 60 RA patients and 75 healthy controls were studied. It appeared that DQCARII*194/DRB1*0405/TNFa*117 was part of the extended haplotype predisposed to RA, whereas DRB1*0901/D6S273*128 contributed to susceptibility to RA to a lesser degree in Singaporean Chinese. Additionally, a negative association with DQCAR*186/DRB1*0301/D6S273*122/TNFd*124 was observed. No association with disease development was observed in this study.

Arthritis, Rheumatoid↗
PubMed2001

Development of quantitative structure activity relationships in toxicity prediction of complex mixtures.

AIM: To predict the toxicity of mixtures of halogenated benzenes (narcotics). METHODS: Acute toxicity test of single chemicals and mixtures was performed using Photobacterium phosphoreum. Partition coefficients of mixtures were calculated by a special equation. Quantitative structure-activity relationship (QSAR) studies were carried out based on results of toxicity tests, n-octanol/water partition coefficient (Kow), and partition coefficient of mixtures (Kmix). RESULTS: 1) There was a good relationship between toxicity and lgKow for single compounds. 2) QSAR analysis showed a perfect correlation between the calculated Kmix and the mixture toxicity for binary mixtures. 3) Using the QSAR model of binary mixtures, the toxicity of other related mixtures containing different composition and fraction was predicted very well. CONCLUSION: The toxicity of halogenated benzene mixtures (narcotics) was predicted by QSAR. This kind of study is helpful for assessing the toxicity of narcotic mixtures.

Benzene Derivatives↗
PubMed2000

[Isolation and cytological identification of a desynaptic variant in rice].

A sterile variant was found from the population of a japonica rice variety Lunhui 422. Cytological investigation was conducted in meiosis. It is showed that the sterility was caused by desynapsis. As there were 8.69 bivalents in average occurred to be desynaptic, moreover, the most number of the desynaptic bivalents reached 12 at post diakinsis. It can be considered that the desynaptic variation is a complete desynapsis found in rice so far.

Mutation↗
PubMed1999

HLA microsatellite associations with insulin-dependent diabetes mellitus in Singaporean Chinese.

Singaporean Chinese with insulin-dependent diabetes mellitus (IDDM) have previously been shown to be associated with the DRB1*0301 haplotype and the joint occurrence of DRB1*0301/*0901 and DRB1*0301/*04. The present study extended previous HLA associations by investigating the HLA region using four microsatellites (TNFa, D6S273, TAP1, DQCARII). Seventy-five IDDM patients and 80 healthy controls were studied. TNFa*3 (RR = 2.26), TNFa*12 (RR = 3.30), TAP1*9 (RR = 2.55) showed increased frequencies while TNFa*11 (RR = 0.29), TAP1*4 (RR = 0.50) showed decreased frequencies in patients compared to controls. Linkage analysis suggested that the positive associations of TNFa*3 and TAP1*9 were secondary to that of DRB1*0301. However, TNFa*12 appeared to provide additional risks to IDDM besides the DRB1*0301 haplotype, whereas TNFa*11 and TAP1*4 conferred an independent protective effect against IDDM. Our findings reinforce the notion that susceptibility to and protection against IDDM may include TNF region. In the present study, TNFa*12 seemed to be the primary association in the DRB1*0405 haplotype and may play an independent role in the pathogenesis of IDDM through TNF-alpha function.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Cytological identification of an isotetrasomic in rice and its application to centromere mapping.

The aneuploid with isochromosome or telochromosome is ideal material for exploring the position of centromere in lingkage map. For obtaining these aneuploids in rice, the primary trisomics from triplo-1 to triplo-12 and the aneuploids derived from a triploid of indica rice variety Zhongxian 3037 were carefully investigated. From the offsprings of triplo-10, a primary trisomic of chromosome 10 of the variety, an isotetrasomic "triplo-10-1" was obtained. Cytological investigation revealed that a pair of extra isochromosomes of triplo-10-1 were come from the short arm of chromosome 10. In the offsprings of the isotetrasomic, a secondary trisomic "triplo-10-2", in which the extra- chromosome was an isochromosome derived from the short arm of chromosome 10, was identified. With the isotetrasomic, secondary trisomic, primary trisomic and diploid of variety Zhongxian 3037, different molecular markers were used for exploring the position of the centromere of chromosome 10. Based on the DNA dosage effect, it was verified that the molecular markers G1125, G333 and L169 were located on the short arm, G1084 and other 16 available molecular markers were on the long arm of chromosome 10. So the centromere of chromosome 10 was located somewhere between G1125 and G1084 according to the RFLP linkage map given by Kurata et al[1]. The distance from G1125 to G1084 was about 3.2 cM.

Aneuploidy↗
PubMed1992

Protective effect of puerarin against myocardial reperfusion injury. Myocardial metabolism and ultrastructure.

To ascertain the beneficial effect of puerarin on the myocardium against reperfusion injury, studies on myocardial metabolism and ultrastructure were made. Twelve dogs divided into two equal groups were placed on moderate hypothermic cardiopulmonary bypass, and their hearts were subjected to 140 minutes cold cardioplegic arrest and 60 minute reperfusion. In the control group, the hearts were perfused with crystalloid cardioplegic solution (CPS) every 20 minutes during arrest. In the treated group, the hearts received CPS containing puerarin (2 mg/kg). Myocardial oxygen consumption, lactate production, creatine phosphokinase (CPK) release, water content and ultrastructural alterations were determined before ischemia, during cardiac arrest and at reperfusion. The results showed that intermittent infusion of CPS containing puerarin significantly decreased myocardial lactate production during ischemia, as well as myocardial oxygen consumption, CPK release and water content during reperfusion. Under electronmicroscopy, the degree of ischemic damage judged by a scoring method was less pronounced in the puerarin group than in the control. The authors conclude that puerarin has protective effects on the function of hearts that have undergone long periods of arrest and reperfusion.

Animals↗
PubMed1992

The protective effect of puerarin against myocardial reperfusion injury. Study on cardiac function.

In order to find out if puerarin could protect the hearts from myocardial reperfusion injury after cardiac arrest, twelve dogs divided into two equal groups were placed on moderately hypothermic cardiopulmonary bypass and their hearts were subjected to 140 min of cold cardioplegic arrest and 60 min of reperfusion. In the control group, the hearts were perfused with a crystalloid cardioplegic solution (CPS) through the aortic root every 20 min during arrest. In the treated group, the hearts received CPS containing puerarin (2 mg/kg). Cardiac hemodynamic variables were monitored throughout the experiments. Left ventricular function curves were formed before ischemia and after 60 min of reperfusion. The results showed that the recovery of left ventricular function in the treated group was significantly better than that in the controls (81 +/- 11% versus 39 +/- 7%, P less than 0.01). Compared with preischemic values, the increase of coronary blood flow (CBF) at cardiac arrest in the puerarin-treated group was higher than that in the control group (214 +/- 11 versus 177 +/- 4 ml/min, P less than 0.01). The data indicate that puerarin has protective effects on the cardiac function after prolonged arrest and reperfusion.

Animals↗
PubMed1991

Functional studies in the human submandibular duct cell line, HSG-PA, suggest a second salivary gland receptor subtype for nucleotides.

Extracellular nucleotides, acting through P2 purinoceptors, have been implicated in the regulation of ion transporting epithelia, including salivary gland acini. Multiple P2 purinoceptor subtypes have been suggested, including P2X, P2Y and P2U (or nucleotide) subtypes, as well as the P2Z subtype found in rat parotid acinar cells. We investigated responses to ATP, ATP analogs and UTP in transformed human submandibular gland duct cells (HSG-PA), in order to compare duct cell purinoreceptors with those in acinar cells. ATP, UTP and some ATP analogs increased, with different potencies, inositol phosphate accumulation, calcium mobilization and potassium efflux. Nucleotide-stimulated calcium mobilization occurred in the absence of, but was enhanced by, extracellular calcium, and maximal potassium efflux required extracellular calcium. UTP and ATP demonstrated equal potencies of about 1 microM and similar efficacies in eliciting these responses, and identical rank orders of potency for stimulating calcium mobilization and potassium efflux were obtained: UTP = ATP greater than ATP gamma S greater than ADP greater than ADP beta S, with alpha,beta-methylene-ATP and 2-methylthio-ATP having little or no effect. Agents reported to block nucleotide effects in parotid acini were ineffective in HSG-PA cells, and experiments in Mg(++)- and Ca(++)-free medium did not indicate that a form of ATP other than MgATP was the active species at the HSG-PA purinoceptor. The extracellular nucleotide effects were not altered by pertussis toxin. These results indicate the presence of a P2U or nucleotide receptor subtype in HSG-PA submandibular duct cells distinguishable from the P2Z purinoceptor of rat parotid acinar cells, suggesting involvement of multiple nucleotide receptor subtypes in salivary gland regulation.

Adenosine Triphosphate↗
PubMed1990

Rheological properties of the extracellular polysaccharide from Agrobacterium sp.S-1231.

A strain of Agrobacterium sp. S-1231 was isolated from one of the soil samples taken from Beijing area. In 4 days' cultivation it was found to produce extracellular polysaccharide and about 24 grams per liter of sugar-containing substrate. At the same concentrations, the polymer produced higher viscosity than that of xanthan gum (Kelzan). The viscosities of 0.2%, 0.5% and 1.0% solutions of this polymer were found to be 840, 5200 and 15000 cp respectively, measured with a Brookfield LVF viscosimeter at 6 rpm. Besides its pseudoplastic rheological properties and the excellent stability towards pH, it had unusual compatibility with high levels of salts and provided shear thinning properties similar to that in fresh water. Moreover, it is also compatible with cationic dyes without precipitation. Unlike other microbial polysaccharides, the viscosities of this polymer remained constant at different temperatures under 65 degrees C, but it decreased sharply in a narrow range of temperatures between 70-75 degrees C.

Cations↗