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Biomedical subjects

X Guo

Publications and source records attributed to X Guo.

At least 235 records · Page 13Linked to original sources
PubMed1999

[Isolation and identification of two flavonoids from Taraxacum mongolicum Hand.-Mazz].

OBJECTIVE: To study the chemical constituents of Taraxacum mongolicum. METHOD: Compounds were separated by column chromatography on silica gel and polyamide, and their structures were determined by spectral analysis and chemical evidence. RESULT: Two flavonoid compounds were separated and elucidated as isoquercitrin and hyperin. CONCLUSION: These two compounds were isolated from the plant for the first time.

Flavonoids↗
PubMed1999

[The detection and clinical significance of telomerase activity in supraglottic carcinomas].

OBJECTIVE: To study the expression and significance of telomerase activity in laryngeal carcinoma. METHOD: We detected telomerase activity of HEP-2 cell line, 26 cases of supraglottic carcinoma tissues and 15 cases of peri-carcinoma tissues with PCR-based assay designated TRAP (for telomeric repeat amplification protocol). RESULT: The telomerase positive rate of supraglottic carcinoma 84.6% (22/26) was obvious higher than that of peri-carcinoma 40% (6/15), P < 0.01. No significant differences in positive rates were found among different groups divided according to clinical stage or metastasis of cervical lymph node, P > 0.05. CONCLUSION: Telomerase activation is related to immortalization process, though not much helpful in diagnosis of supraglottic carcinoma.

Adult↗
PubMed1999

[Biocompatibility of self-designed absorbable hydroxyapatite/poly (DL-lactide) composites].

The biocompatibility of self-designed hydroxyapatite/poly (DL-lactide) rods was evaluated both in vitro and in vivo including Ames test, micronucleus test, acute and subacute systemic toxicity test, hemolysis test, hemopexis test and long-term muscle and bone implant test. The results indicate that the material has no toxicity, no stimulation and mutation, and it does not cause hemolysis and hemopexis. Consequently, the biocompatibility of the composite was good.

Absorbable Implants↗
PubMed1999

[The properties of new affinity adsorbent for adsorbing the cycle immune complex in blood].

This study was designed to select an affinity adsorbent from 5 kinds of adsorbents available. The adsorbent AA3 was found being specific to the adsorption of pathologic cycle immune complex (CIC). The physical properties such as specific surface area, proe volume and average pore diameter of adsorbents were determined. A discussion on the factors that affect the adsorption of CIC is also presented in this paper.

Adsorption↗
PubMed1999

[Breeding of yeast for beer manufacturing by inactivated protoplast fusion].

QSB-XI6, one of fusants, was obtained by PEG-induced fusion between UV-inactivated protoplasts of Saccharomyces cerevisiae LQ16 (Ile-, Datr) and heat-inactivated protoplasts of S. cerevisiae QSB7(Ala-, H2S-). The cell volume, bicmass, genotype and DNA content of the fusant were measured in comparison with of its parents and the results showed that QSB-XI6 was a fusant. The fermentation ability and the flocculent capacity of this fusant were higher than those of its parents. The diacetyl content of the beer produced by the fusant was measured and some other compositions of the beer was also analysed by gas chromatography. The sensory evaluation of the beer was much better and the flavour was distinctive. The results of many production trials in succession showed that all good characteristics of QSB-XI6 were stable.

Cell Fusion↗
PubMed1999

[Light-dependent incorporation of selenite into selenocysteine by isolated chromatophore of Chromatium vinosum].

Illiminated intact chromatophore of chromatium vinosum in the presence of O-acetylserine(OAS) catalysed incorporation of SeO3(2-) into selenocysteine at rate of 359 nmol.mgBchl-1.h-1. Sonicated chromatophore catalysed SeO3(2-) incorporation at 1.1% of the rate of intact chromatophore. Addition of GSH and NADPH increased the rate to 88.3% of intact rate, but SeO3(2-) incorporation under these conditions was essentially light dependent. The purified GSH reductase from Chromatium vinosum in the presence of cysteine synthase OAs and NADPH catalysed incorporation of SeO3(2-) into selenocysteine. It is proposed that SeO3(2-) is reduced by light-coupled GSH reductase and that Se2- produced is incorporated into selenocysteine by cysteine synthase.

Catalysis↗
PubMed1999

[Establishment of a rabbit model of Acanthamoeba keratitis].

AIM: To establish an animal model of Acanthamoeba keratitis. METHODS: Six New Zealand white rabbits were each injected intrastromally with Acanthamoeba suspension 3 days after subconjunctival injection with dexamethasone. RESULTS: All of the 6 rabbits developed keratitis. Acanthamoeba protozoa were identified by the methods of corneal scraping with 10% potassium hydroxide wet mount examined under microscope, corneal protozoa culture and pathological section examination. CONCLUSION: A rabbit model of Acanthamoeba keratitis was established.

Acanthamoeba Keratitis↗
PubMed1999

[GC-MS analysis of volatile oil of herba Pogostemonis collected from Gaoyao county].

The chemical constituents of the volatile oil of the stems and leaves of Pogostemon cablin collected from Gaoyao county, Guangdong province, have been studied by means of GC-MS. Sixty four compounds have been identified. The main constituents are pogostone (30.99% in stems, 21.31% in leaves, the same below), patchouli alcohol (10.26%, 37.53%), transcaryophyllene (4.92%, 6.75%), alpha-guaiene (2.27%, 6.18%) and seychellene (1.56%, 1.99%), etc.

China↗
PubMed1999

Differential gene expression in retina of myopic chicken eyes using mRNA differential display.

PURPOSE: To study differentially expressed genes in retina of experimental myopic chicken. METHODS: Experimental myopia in chicken was induced by form-deprivation. The mRNA in chicken retina was analyzed by using differential display. RESULTS: Experimental myopia was successfully induced in chicken through form-deprivation. Differentially expressed gene fragments were detected in retina of chicken with myopic development and recovery as compared with normal controls. CONCLUSION: The differential display of mRNA may be a useful way in cloning myopic-related genes.

Animals↗
PubMed1999

[Long-term follow-up result of partial laryngectomy in senile patients with laryngeal carcinoma].

OBJECTIVE: To study the long-term follow-up result of laryngectomy with reservation of laryngeal function in senile patients. METHODS: Ninety-nine patients who were above 65 years old and underwent partial laryngectomies from 1986 to 1990 were summarized. Among them, 14 cases underwent vocal cord resection, 31 vertical hemilaryngectomy, 15 horizontal supraglottic hemilaryngectomy, 2 horizontal glottic laryngectomy, 22 horizontovertical (3/4) laryngectomy, 5 subtotal laryngectomy, 10 total laryngectomy with cricopharyngeal anastomosis. RESULTS: All patients had their phonation and respiration restored. Decannulation rate was 91.9%. No death occurred during the operation. No severe postoperative complications were found. 3.5-year survival rates were 76.7% and 75.5% respectively. CONCLUSION: Senility is not a contraindication for laryngectomy with reservation of laryngeal function. The key points are that surgeons should master indications correctly and improve surgical skill to decrease postoperative complications.

Aged↗
PubMed1999

[Photocurrent spectra of undoped LECSIGaAs].

Extrinsic photocurrent spectra of undoped LECSIGaAs have been measured to investigate the deep levels in this material. A broad photocurrent response band M1 ranging from 0.40 to 0.70 eV has been observed. M1 band reveals five peaks at 0.46, 0.49, 0.56, 0.65 and 0.69 eV, respectively. The onset thresholds for the 0.46, 0.49, 0.56 and 0.69 eV peaks are 0.44, 0.47, 0.51 and 0.67 eV, respectively. It is likely that M1 band is due to different deep levels and each of these deep levels has a concentration larger than 10(14) cm(-3). The origin of M1 band is discussed and possible associations of the 0.44, 0.47 and 0.51 eV thresholds with copper acceptor, EL3 and oxygen donor are presented. The relationship between M1 band and the photoresponse behavior of drain current of GaAs field effect transistor was also investigated.

English Abstract↗
PubMed1999

[Study on the determination of aluminum in soil samples by air-acetylene flame atomic absorption spectrometry].

This paper reported a method for the direct determination of aluminum in soil samples by air-acetylene flame atomic absorption spectrometry. The enhancement effect on aluminum of adding tetramethylammonium chloride was studied. 43 microg/mL/1% of characteristic concentration was reached. This method is simple, rapid and useful, and has been applied to the determination of aluminum in standard soil samples, and a good agreement was achieved.

Acetylene↗
PubMed1999

[Determination of trace amounts of zinc in nickel electrolyte by flow injection on-line enrichment].

A method for the determination of trace amount of zinc in nickel electrolyte utilizing the flow injection on-line enrichment technique is reported in this paper. Atomic absorption spectrometer was used as detector. Zinc was separated from large amounts of nickel andother components in the electrolyte by absorption its chlorocomplex on a mini-column packed with strongly basic anion exchangers. It was found that sodium chloride containing in the electrolyte offered a sufficient chloride concentration needed for the formation of the zinc chlorocomplex and thus no additional reagent was required for the determination. The throughput of the method is 30 determinations per hour. The detection limit of the method is 0.002 microg x mL(-1) and the precision is 1.9% (RSD). The proposed method is rapid and cost-effective. It has been used for almost three years in the quality control of the electrolyte in the factory with great success.

English Abstract↗
PubMed1998

nm23-H1 expression in nasopharyngeal carcinoma: correlation with clinical outcome.

The expression levels of nm23-H1 mRNA and its protein in human nasopharyngeal carcinoma (NPC) were detected to clarify the relationship between nm23-H1 and metastasis and prognosis of patients with NPC. nm23-H1 mRNA expression in fresh tissues from 78 patients with NPC was investigated by in situ hybridization and RT-PCR. Routine labeling streptavidin-biotin immuno-histochemistry with the nm23-H1 murine monoclonal antibody was employed to study the expression of nm23-H1 protein in paraffin-embedded specimens from 231 patients with NPC treated in our hospital. The clinical pathologic data and results of follow-up were collected. Comparisons between expression of nm23-H1 protein or mRNA and clinical outcome were performed using the chi2 test. Multivariate prognostic analyses were performed by the Cox regression model. We found that nm23-H1-negative tumors were associated with a higher incidence of lymph-node metastasis (84.2%) than nm23-H1-positive ones (32.8%, p < 0.01). The distant metastasis and loco-regional recurrence rates in the nm23-H1-negative group were 55.8% and 31.68%, respectively but only 17.2% and 11.5%, respectively, in the nm23-H1-positive group (p < 0.01). A significant association was found between expression of nm23-H1 protein and prognosis (p < 0.01). Expression of nm23-H1 protein indicated favorable prognosis, suggesting that the absence of nm23-H1 protein expression was significantly associated with lymph-node metastasis, recurrence and distant metastasis in NPC. Expression of the nm23-H1 gene may be valuable for assessing the prognosis of NPC.

Adolescent↗