Search PubMed⌕ Search

Biomedical subjects

Y Huang

Publications and source records attributed to Y Huang.

At least 289 records · Page 16Linked to original sources
PubMed2001

[Value of regional intra-arterial induction chemotherapy for locally advanced nasopharyngeal carcinoma].

OBJECTIVE: To define the value of regional intra-arterial induction chemotherapy for locally advanced nasopharyngeal carcinoma (NPC). METHODS: 121 locally advanced NPC(stage III-IV) patients confirmed by pathology were randomly divided into two groups before radiation, and the two groups were given two different methods of chemotherapy: regional intra-arterial chemotherapy (IACT) and systemic chemotherapy (SCT). After radiation the effect of two methods was compared. RESULTS: The complete response rates were 27.9% in the IACT and 11.7% in the SCT, and 5 years survival rates were 63.9% in the IACT and 45.0% in the SCT respectively. The differences of two groups were significant. CONCLUSION: IACT is more reasonable than SCT as induction chemotherapy for these locally advanced NPC.

Adolescent↗
PubMed2001

[Important prognostic factors in patients with skull base erosion from nasopharyngeal carcinoma after radiotherapy].

OBJECTIVE: To evaluate the long-term outcome and prognostic factors in patients with skull base erosion from nasopharyngeal carcinoma (NPC) after initial radiation therapy. METHODS: From January 1985 to December 1986, 100 patients (71 male, 29 female) with the diagnosis of NPC were found to have skull base erosion from computed tomography (CT). The mean age was 41 (16-66) years. Ninety-six patients had World Health Organization (WHO) type III undifferentiated carcinoma while four had type I carcinomas. Metastatic workup including chest radiography, liver ultrasound and liver function test were negative. All patients underwent external beam radiotherapy alone to 66-80 Gy over 6-8 weeks. Daily fraction size of 2 Gy was delivered utilizing cobalt-60 or linear accelerator. No patient received chemotherapy. All patients were followed up at regular intervals after irradiation. Median follow-up was 22.3 months (2 months-174 months). Overall survival of the cohort was computed by the Kaplan-Meier method. Potential prognostic factors on survival were examined. Multivariate analyses was performed using Cox regression model. RESULTS: One, three, five, and ten year overall survival rates for the cohort were 79%, 38%, 27% and 13%, respectively. However, in the sub-group of patients with both anterior cranial nerves (I-VIII) and posterior cranial nerve (IX-XII) involvement had a five-year survival of only 7.7%. Causes of death included local recurrence (59 patients), distant metastases (21 patients), both local recurrence and distant metastases (1 patient) and unrelated causes (5 patients). After multivariate analysis, complete recovery of cranial nerve involvement, cranial nerves palsy and recovery of headache after irradiation were found to be independent prognostic factors in this cohort. CONCLUSION: This report presents one of the longest follow-ups of patients with nasopharyngeal carcinoma invading skill base. It demonstrates the importance of cranial nerves involvement as well as recovery of headache and cranial nerve palsy. These factors should be evaluated carefully from history and physical examination as well as imaging studies. Currently available magnetic resonance imaging (MRI) is highly recommended as an additional test. A subgroup of patients with skull base involvement had long-term survival after radiotherapy alone. More aggressive strategy such as combined chemo-radiotherapy and altered fractionation radiotherapy may improve outcome in patients with poor prognostic factors.

Adolescent↗
PubMed2001

[New applications of FTIR micro-spectroscopy in the field of forensic science].

The new applications of FTIR micro-spectroscopy in the field of forensic science are presented, and the process and results of infrared spectra measurements of many kinds of samples, such as paint, fiber, dye, plastic, rubber, ink and drug have been discussed in detail, including two real cases. Various sampling accessories (Diamond cell, Attenuated total reflection and Micro manipulator system) and different determination modes (transmission and reflectance) are used according to the properties of samples.

Coloring Agents↗
PubMed2001

[The Raman vibrational characteristics and assignments of three Schiff bases].

The Raman vibrational characteristics of three asymmetric Schiff bases were studied in this paper. By referring to the characteristic Raman spectra of substituent benzene and oxamidoxime compounds, the Raman vibrational modes of three Schiff bases were analyzed and assigned, respectively. The difference of their Raman spectra mainly arises from their different vibrational energy level resulting from the C-OH group to most extents. This result is of importance for further investigating the properties of these three new-type Schiff bases.

Benzene↗
PubMed2001

[The charge transferring between silver nanoparticles and R6G].

In this paper, we studied the charge transferring between silver nanoparticles and R6G molecules by UV-Vis absorption spectra, SERS and fluorescence spectra. The results indicate that the charge transferring process can be completed by forming complex between silver nanoparticles and R6G molecules. As a result, the absorption band of complex can be seen in the absorption spectra, the Raman modes of R6G are largely enhanced and the fluorescence of R6G is effectively quenched.

Chemical Phenomena↗
PubMed2001

[Study on the energy transfer fluorescence quenching among combination of acridine yellow-PAR determination of trace iron].

An energy transfers technique between 4-(2-Pyridylazo) resorcinol(PAR) and acridine yellow is studied, and optimum experimental conditions of energy transfer is done as well. It is found that in the aqueous solution of sodium lauryl sulfate, NH3.H2O-NH4Cl buffer solution at pH = 9.2, the energy transfers from acridine yellow to iron(II)-PAR complexes. So a new method of fluorometric energy transfers determination of trace iron(II) by acridine yellow--PAR was described. The range of determination of iron is 0-10 micrograms.L-1. The detection limit for iron is 0.06 microgram.L-1. The method has been applied to the determination of iron in water sample and hair with satisfactory results.

Aminoacridines↗
PubMed2001

Neurological disease: listening to gene silencers.

Neurons regulate the expression of genes essential to individual neuron function through elegant combinatorial interactions among a limited number of transcription factors. In addition, an economy of regulatory control is practiced within the nucleus that belies conceptual divisions of transcription factors into "repressors" and "activators." Studies of the neural restrictive silencer element (NRSE, also known as RE1) and its repressor protein have revealed a multitude of mechanisms by which transcriptional regulation is not only elaborated in normal neuronal development, but perverted in disease states.

Animals↗
PubMed2000

Genomic organization and alternative transcripts of the human PQBP-1 gene.

PQBP-1 has been identified as a protein that binds to huntingtin, androgen receptor and transcription factor Brain-2 through their homopolymeric glutamine repeats. We here report the genomic organization of the human PQBP-1 gene and its multiple alternative transcripts. The coding region of PQBP-1 comprises six exons and five introns, and four types of alternative transcript, designated PQBP-1a to PQBP-1d, were found in addition to the PQBP-1 transcript reported originally. All of the PQBP-1 transcripts retain the WW domain in the N-terminal region, a potent transactivator domain. On the other hand, there is a wide variation in their C-terminal regions. Importantly, PQBP-1a and PQBP-1d lack the domain responsible for the interaction with homopolymeric glutamine repeats and a nuclear localization signal.

Alternative Splicing↗
PubMed2000

Characterization of (125)I-IABN, a novel azabicyclononane benzamide selective for D2-like dopamine receptors.

The properties of an (125)I-labeled structural analog of 2, 3-dimethoxy-N-[9-(4-fluorobenzyl)-9-azabicyclo[3.3. 1]nonan-3beta-yl]benzamide (MABN), (125)I-IABN, are described. (125)I-IABN was developed as a high-affinity radioligand selective for the D2-like (D2, D3, and D4) dopamine receptor subtypes. (125)I-IABN binds with picomolar affinity and nonselectively to rat D2 and D3 dopamine receptors expressed in Sf9 and HEK 293 cells. (125)I-IABN binds with 7- to 25-fold lower affinity to human D4.4 dopamine receptors expressed in HEK 293 cells. Dissociation constants (Kd) calculated from kinetic experiments were in agreement with equilibrium Kd values obtained from saturation binding studies. Saturation plots of the binding of (125)I-IABN with rat caudate membrane preparations were monophasic and exhibited low nonspecific binding. The pharmacologic profile of the binding of (125)I-IABN to rat caudate was consistent with a D2-like receptor, suggesting that the ligand binds primarily to D2 dopamine receptors. In addition, IABN was found to bind with low affinity to D1 dopamine receptors, as well as to the sigma1 and sigma2 receptor subtypes. Quantitative autoradiographic studies using rat brain slices indicate that (125)I-IABN selectively labels the striatum and the olfactory tubercle area, which is consistent with the labeling of D2-like receptors. IABN blocks dopamine-dependent inhibition of adenylyl cyclase activity at D2 or D4.4 receptors expressed in HEK cells. Therefore, (125)I-IABN appears to be a high-affinity, selective antagonist at D2-like dopamine receptors. Finally, a unique property of the azabicyclononane benzamide (125)I-IABN compared to previously studied substituted benzamides is that the binding of this radioligand is not effected by variations in Na(+) concentration.

Animals↗
PubMed2000

Taxol from Tubercularia sp. strain TF5, an endophytic fungus of Taxus mairei.

The diterpenoid taxol is an important anticancer agent used widely in the clinic. The purpose of this work was to identify a taxol-producing endophytic fungus (strain TF5) isolated from Taxus mairei and study its anticancer activities. Strain TF5 was identified as a Tubercularia sp. according to the morphology of the fungal culture, the mechanism of spore production and the characteristics of the spores. Strain TF5 produced taxol, when grown in potato dextrose liquid medium and analyzed by thin layer chromatography, high performance liquid chromatography, ultraviolet and mass spectrometry. The fungal taxol, which was isolated from the organic extract of the TF5 culture, had strong cytotoxic activity towards KB and P388 cancer cells in vitro, tested by the MTT assay. Observed with immunofluorescence and electron microscopy, the fungal taxol enhanced microtubule stability and bundling in culture cells and induced tubulin polymerization in vitro similar to the authentic taxol.

Animals↗
PubMed2000

Effect of resveratrol on intimal hyperplasia after endothelial denudation in an experimental rabbit model.

The ability of resveratrol to inhibit vascular intimal thickening was tested in an experimental model in which endothelial denudation was performed in the normal rabbit iliac artery. Resveratrol (2 approximately 4mg/ kg/d) was administered intragastrically for 5 weeks beginning 1 week before denudation. At the higher concentration of resveratrol, the intimal hyperplasia of injured vascular wall was effectively inhibited; the intimal proliferation index also was significantly less than that in the untreated control group (0.28 +/- 0.07 vs 0.41 +/- 0.13, respectively, p<0.01); the relative luminal area increased from 0.38 +/- 0.06 in the untreated control group to 0.53 +/- 0.10 in the resveratrol treatment group (p < 0.001); and the count of smooth muscle cells in the thickened intima was statistically significantly reduced in the high dose resveratrol treatment group than that in the untreated group (1,115 +/- 510 vs 1,796 +/- 963, respectively, p < 0.05). Resveratrol added to the culture media of cultured rabbit vascular smooth muscle cells inhibited DNA synthesis in a dose-dependent manner. These results showing that resveratrol is capable of inhibiting intimal hyperplasia of injured artery raise the possibility that this polyphenol might have clinical potential in prevention and treatment of restenosis after angioplasty.

Animals↗
PubMed2000

Low chloride stimulation of prostaglandin E2 release and cyclooxygenase-2 expression in a mouse macula densa cell line.

Reducing luminal NaCl concentration in the macula densa region of the nephron stimulates renin secretion, and this response is blocked by a specific inhibitor of cyclooxygenase-2 (COX-2) (Traynor, T. R., Smart, A., Briggs, J. P., and Schnermann, J. (1999) Am. J. Physiol. Renal Physiol. 277, F706-710). To study whether low NaCl activates COX-2 activity or expression we clonally derived a macula densa cell line (MMDD1 cells) from SV-40 transgenic mice using fluorescence-activated cell sorting of renal tubular cells labeled with segment-specific fluorescent lectins. MMDD1 cells express COX-2, bNOS, NKCC2, and ROMK, but not Tamm-Horsfall protein, and showed rapid (86)Rb(+) uptake that was inhibited by a reduction in NaCl concentration and by bumetanide or furosemide. Isosmotic exposure of MMDD1 cells to low NaCl (60 mm) caused a prompt and time-dependent stimulation of prostaglandin E(2) (PGE(2)) release that was prevented by the COX-2 specific inhibitor NS-398 (10 microm). Reducing NaCl to 60 and 6 mm for 16 h increased COX-2 expression in a chloride-dependent fashion. Low NaCl phosphorylated p38 kinase within 30 min and ERK1/2 kinases within 15 min without changing total MAP kinase levels. Low NaCl-stimulated PGE(2) release and COX-2 expression was inhibited by SB 203580 and PD 98059 (10 microm), inhibitors of p38 and ERK kinase pathways. We conclude that low chloride stimulates PGE(2) release and COX-2 expression in MMDD1 cells through activation of MAP kinases.

Animals↗
PubMed2000

Induction of apoptosis in prostate cancer cell lines by a flavonoid, baicalin.

The flavonoid baicalin (baicalein 7-D-beta-glucuronate), isolated from the dried root of Scutellaria baicalensis Georgi (Huang Qin), is widely used in the traditional Chinese herbal medicine for its anti-inflammatory, anti-pyretic and anti-hypersensitivity effects. In the present study, we investigated the in vitro effects of baicalin on the growth, viability, and induction of apoptosis in several human prostate cancer cell lines, including DU145, PC-3, LNCaP and CA-HPV-10. The cell viability after treating with baicalin for 2-4 days was quantified by a colorimetric 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-s ulfophenyl)- 2H-tetrazolium (MTS) assay. The results showed that baicalin could inhibit the proliferation of prostate cancer cells. The responses to baicalin were different among different cell lines, with DU145 cells being the most sensitive and LNCaP cells the most resistant. Baicalin caused a 50% inhibition of DU145 cells at concentrations of 150 microM or above. The inhibition of proliferation of prostate cancer cells after a short period of exposure to baicalin was associated with induction by apoptosis, as evidenced by the typical nuclear fragmentation using Hoechst 33258 staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) labeling, DNA fragmentation, activation of caspase-3 and cleavage of poly-ADP-ribose polymerase (PARP). The results indicate that baicalin has direct anti-tumor effects on human prostate cancer cells.

Androgens↗
PubMed2000

Hetero Diels-Alder reactions of 1-amino-3-siloxy-1,3-butadienes under strictly thermal conditions.

The hetero Diels-Alder reaction of 1-amino-3-siloxy-1,3-butadiene (1a) with a range of unactivated aldehydes proceeds readily under remarkably mild conditions: at room temperature and in the absence of Lewis acid catalysts. The cycloadducts are formed in good yields and can be converted directly to the corresponding dihydro-4-pyrones using acetyl chloride. Ketones and imines are also reactive in hetero Diels-Alder reactions with this diene.

Butadienes↗
PubMed2000

Effects of site-directed mutagenesis on structure and function of recombinant rat liver S-adenosylhomocysteine hydrolase. Crystal structure of D244E mutant enzyme.

A site-directed mutagenesis, D244E, of S-adenosylhomocysteine hydrolase (AdoHcyase) changes drastically the nature of the protein, especially the NAD(+) binding affinity. The mutant enzyme contained NADH rather than NAD(+) (Gomi, T., Takata, Y., Date, T., Fujioka, M., Aksamit, R. R., Backlund, P. S., and Cantoni, G. L. (1990) J. Biol. Chem. 265, 16102-16107). In contrast to the site-directed mutagenesis study, the crystal structures of human and rat AdoHcyase recently determined have shown that the carboxyl group of Asp-244 points in a direction opposite to the bound NAD molecule and does not participate in any hydrogen bonds with the NAD molecule. To explain the discrepancy between the mutagenesis study and the x-ray studies, we have determined the crystal structure of the recombinant rat-liver D244E mutant enzyme to 2.8-A resolution. The D244E mutation changes the enzyme structure from the open to the closed conformation by means of a approximately 17 degrees rotation of the individual catalytic domains around the molecular hinge sections. The D244E mutation shifts the catalytic reaction from a reversible to an irreversible fashion. The large affinity difference between NAD(+) and NADH is mainly due to the enzyme conformation, but not to the binding-site geometry; an NAD(+) in the open conformation is readily released from the enzyme, whereas an NADH in the closed conformation is trapped and cannot leave the enzyme. A catalytic mechanism of AdoHcyase has been proposed on the basis of the crystal structures of the wild-type and D244E enzymes.

Adenosylhomocysteinase↗
PubMed2000

Isolation and cloning of four subunits of a fission yeast TFIIIC complex that includes an ortholog of the human regulatory protein TFIIICbeta.

Eukaryotic tRNA genes are controlled by proximal and downstream elements that direct transcription by RNA polymerase (pol) III. Transcription factors (TFs) that reside near the initiation site are related in Saccharomyces cerevisiae and humans, while those that reside at or downstream of the B box share no recognizable sequence relatedness. Human TFIIICbeta is a transcriptional regulator that exhibits no homology to S. cerevisiae sequences on its own. We cloned an essential Schizosaccharomyces pombe gene that encodes a protein, Sfc6p, with homology to the S. cerevisiae TFIIIC subunit, TFC6p, that extends to human TFIIICbeta. We also isolated and cloned S. pombe homologs of three other TFIIIC subunits, Sfc3p, Sfc4p, and Sfc1p, the latter two of which are conserved from S. cerevisiae to humans, while the former shares homology with the S. cerevisiae B box-binding homolog only. Sfc6p is a component of a sequence-specific DNA-binding complex that also contains the B box-binding homolog, Sfc3p. Immunoprecipitation of Sfc3p further revealed that Sfc1p, Sfc3p, Sfc4p, and Sfc6p are associated in vivo and that the isolated Sfc3p complex is active for pol III-mediated transcription of a S. pombe tRNA gene in vitro. These results establish a link between the downstream pol III TFs in yeast and humans.

Alleles↗
PubMed2000

Vibrational promotion of electron transfer.

By using laser methods to prepare specific quantum states of gas-phase nitric oxide molecules, we examined the role of vibrational motion in electron transfer to a molecule from a metal surface free from the complicating influence of solvation effects. The signature of the electron transfer process is a highly efficient multiquantum vibrational relaxation event, where the nitrogen oxide loses hundreds of kilojoules per mole of energy on a subpicosecond time scale. These results cannot be explained simply on the basis of Franck-Condon factors. The large-amplitude vibrational motion associated with molecules in high vibrational states strongly modulates the energetic driving force of the electron transfer reaction. These results show the importance of molecular vibration in promoting electron transfer reactions, a class of chemistry important to molecular electronics devices, solar energy conversion, and many biological processes.

Journal Article↗