Biomedical subjects

G Xu

Publications and source records attributed to G Xu.

At least 235 records · Page 13Linked to original sources

PubMed1999

[The genotype of vac A gene of Helicobacter pylori (Hp) and its correlation with the gastroduodenal diseases associated with Hp].

OBJECTIVE: To analyze the expression of vac A gene of Helicobacter pylori (Hp) isolated from Chinese patients and to find out the relationship between the genotype of Hp vac A and the gastroduodenal diseases associated with Hp. METHODS: Clones of Hp obtained from patients with gastroduodenal diseases were cultured and mRNA extraction was performed with reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: 92% of the strains isolated in Shanghai (China) was found to be s1/m2. Strains expressing s1/m1 forms were obtained in 4 cases. s2 form was not found. CONCLUSION: The overwhelming majority of strains isolated from Shanghai patients expresses s1/m2 from. The s1/m2 genotype is dispersed in all of the gastroduodenal diseases associated with Hp.

Adolescent↗

PubMed1999

[Morphological cure of cerebral arteriovenous malformations by endovascular therapeutics].

OBJECTIVE: To sum up the clinical characteristics and typical manifestation by analysing clinical materials from total embolized cerebral arteriovenous malformations (AVM) via endovascular embolization. METHODS: We reviewed clinical and image materials of 50 patients whose cerebral AVM were embolized entirely and found the cerebral AVM morphological cure by endovascular embolization after studying the size, position, artery supply, therapeutics and follow-up. RESULTS: 50 patients with cerebral AVM were embolized by endovascular therapy, accounting for 17% of all patients. Malformation lesions were medium or small type, with a diameter less than 3 cm, 95% of them were located in the tentorium superior. Terminal end blood supply was common to AVM and especially medium cerebral artery (MCA) or its branches. 97% of the patients were graded III or below by spectzler grading system. 70% of them had a history of intracranial hemorrhage and were cured by one therapy. CONCLUSIONS: It is a reliable and feasible method for morphological cure in cerebral AVM via endovascular therapeutics only, but case selection is important, that is, medium or small AVM with single branch terminal end blood supply in the tentorium superior.

Adolescent↗

PubMed1999

[HPLC determination of uracil xanthine, hypoxanthine and uridine in species of animal drugs].

OBJECTIVE: To make further studies on the water-soluble components in animal drugs by determining the contents of uracil, xanthine, hypoxanthine and uridine from ten species of animal drugs. METHOD: The determination was affected by RP-HPLC, using Shim-pack CLC-ODS column(150 mm x 6 mm), 0.05 mol/L dibasic ammonium phosphate solution as mobile phase, flow rate 0.8 ml/min and detection at 254 nm. RESULTS: This method is accurate, rapid and reproducible. Analytical data for Hirudo nipponia, Eupolyphaga sinensis, Scolopendra subspinipes mutilans, Buthus martensii, Bombyx mori, Mylabris cicorri, Aspongopus chinensis, Lytta caraganae, Tabanus bivittatus and Huechys sanguinea are given. CONCLUSION: There are marked discrepancies in the contents of the four components as shown on the chromatograms, a point that may be helpful in identifying the above-cited ten species of animal drugs.

Animals↗

PubMed1999

[The basic model and its peculiarity of relaxation theory in chromatography].

According to the basic idea of relaxation theory in chemical dynamics and the moving character of the sample molecules in a chromatographic column, a new transfer model was established. It was supposed that solute molecules were in equilibrium between the stationary phase and mobile phase, and transferred in the mobile phase by a way of jumping. The generating function was used to investigate the non-continuous dynamic transfer differential equations, and the basic profile of solute's distribution in the column is gained [formula: see text] Based on this equation, the effect of transfer coefficient on the profile had been explained. The results show that relaxation time is an important factor which is related to the capacity factor and diffusion coefficient, and the number of jumping is a similar parameter to the plate number. The digital calculation method was used to study the influence of different physical parameters on the profile. The continuous form of the profile was also compared with the one from other methods.

English Abstract↗

PubMed1999

Two approaches for determining the urinary excretion patterns of nucleosides--HPLC and CE.

Cancer patients excrete in their urine increased amounts of modified purines and pyrimidines. These modified mucleosides are primary constituents of RNA and are synthesized at the macromolecular level. When RNA is catabolized, most of these modified nucleosides cannot be reutilized; consequently, they are excreted. Due to their increased urinary excretion in conjunction with altered RNA turnover in carcinogenesis, they have been proposed as tumour markers. We developed both reversed-phase high performance liquid chromatographic and capillary electrophoretic approaches to determine normal and modified nucleosides in urine. Data obtained with CE are in good accordance with those from HPLC. The reference excretion levels of urinary nucleosides from healthy volunteers were established, and elevated ones of modified nucleosides from 34 patients with different kinds of cancer were observed. The developed methods are suitable for the analysis of large series of samples for clinical studies.

Biomarkers, Tumor↗

PubMed1999

[Development of column switching systems in industrial gas chromatography].

According to the home-made requirement of column switching systems in 23 industrial gas chromatographs in 300,000 Tons of olefin plant, based on the research work of the expert system on gas chromatography and movement laws of compounds of interest in columns, the suitable stationary phases were defined, and the column switching systems were designed by using combined cutting techniques which consist of backflushing, fore-flushing and heart cutting, and by controlling column lengths, flows, flow directions and temperatures. The practical applications showed the column systems satisfy the on-line monitoring requirement of the production process and can be used continually for 1-3 years.

English Abstract↗

PubMed1999

[The effect of organic modifier on the capacity factor of the solute in the micellar electrokinetic capillary chromatography].

In this paper the mass action law has been used to study the relationship of solute, organic modifier and micelle in the micellar electrokinetic capillary chromatography. A series of equations were given showing the relationship of capacity factor(k) of the solute, equivalent constant, concentration of solute and migration speed under the condition of using only one organic modifier. The results showed that the organic modifier can, to some extent, be dissolved in micelles. It has almost no effect on micellar actual migration speed, but, the organic modifier influences the CMC of surfactants and the distribution of solutes between two phases and results in the change of the capacity factors of the solutes. No simple equations like those in HPLC can be used to show the effect of organic modifier and surfactants on k. At the first approximation, they have the following equation, lnk approximately a + bCB + clnCB where, CB is the total concentration of organic modifier, a, b and c are constants.

English Abstract↗

PubMed1999

[Determination of 2,4-dinitrophenol by solid-phase microextraction coupled to GC/MS].

Solid-phase microextraction coupled GC/MS was investigated for the determination of 2,4-dinitrophenol in aqueous sample. Analytes were extracted by a 85 microns polyacrylate coated fiber. The fiber was then transferred into the injector of GC. Analytes were thermally desorbed and detected by GC/MS. The influences of several parameters on SPME procedure have been studied. The optimization condition was obtained: directly sampling in the water sample with the extraction period was 30 min and the desorption time 3 min at 270 degrees C. Acidification by hydrochloric acid (pH 2) and saturated salt were necessary for the best sensitivity. The precision of SPME is better than that of liquid-liquid extraction. This method is a fast, simple, and pre-concentration-free technique, which is suitable for detecting 2,4-dinitrophenol in water sample.

2,4-Dinitrophenol↗

PubMed1999

[Separation and analysis of amino acids in secretion of psylla chinesis yang et li].

We used ion-exchange resin column chromatography to separate amino acids in secretion of Psylla Chinese Yang et Li and used capillary gas chromatography to analysis n-butyl-N-trifluoracetyl derivatives of the amino acids. Qualitative analysis was done by comparing with the standard amino acids and quantitative analysis by internal standard method. We determined thirteen amino acids in the secretion.

English Abstract↗

PubMed1999

[The isolation of microbe producing biosurfactants].

Microorganisms capable of producing biosurfactants can be isolated by a series of steps including hydrocarbon enrichment culture, hemolytic activity assay on blood agar plates and oil displacement activity assay etc. Ten strains(including bacteria, yeasts and fungi) were isolated with higher surface activity from 1000 samples from soil, sludge, waste water etc. Two strains of bacteria produced rhamnolipids and trehaloselipids respectively. One strain of bacterium produced long chain unsaturated carboxylic acid and another produced azelaic acid. Two strains of yeasts produced lipopolysaccharides with excellent emulsification property.

Bacteria↗

PubMed1999

[The comparison of contents of uracil, xanthine and hypoxanthine in five species of leech].

Three constituents(uracil, xanthine, hypoxanthine) were isolated from five species of leech and determined by reversed phase HPLC. The column employed was Shim-pack CLC-ODS C18(150 mm x 6 mm). The mobile phase was 0.05 mol/l ammonium phophate dibasic solution(pH = 8.4). The flow rate was 0.8 ml/min and detection was effected at 254 nm. This method is accurate, rapid and reproducible. Analytical data for five species and Whitmania pigra samples from different places were given.

Animals↗

PubMed1999

[Pharmacognostical studies on the roots of Euphorbia prolifera].

Morphological and histological characters of the roots of Euphorbia prolifera Buch.-Han., a traditional Chinese medicine, were described and illustrated with line drawings. TLC analysis of the above drug was also undertaken. These studies provide referencial informations for clinics, quality control, development and identification of this crude drug.

Chromatography, Thin Layer↗

PubMed1999

[Pharmacognostical studies on radix Glehniae (Glehnia littoralis)].

OBJECT: To identify the roots of Glehnia littoralis Fr. Schmidt ex Miq., and compare the chemical constituents of the root skin and the roots with no skin. METHODS: The roots were identified by morphological and microscopic identification and TLC. RESULTS: The characteristics of the secretory canal, ray and starch grain can be used to identify the histology and powder of the roots. The chemical constituents of the root skin and the roots with no skin are similar. CONCLUSION: The characteristics of the morphology, histology and powder can be used to identify the roots of Glehnia littoralis (Radix Glehniae).

Apiaceae↗

PubMed1999

[Possibility and clinical significance of reservation middle turbinate in endoscopic sinus surgery].

OBJECTIVE: To study the possibility and significance or reservation of the middle turbinate in endoscopic sinus surgery for sinusitis and/or nasal polyps. METHODS: (1) The morphology and mucosal ultrastructure of middle turbinate were observed preoperatively and postoperatively by nasal endoscopy and scanning electron microscopy in 20 cases; (2) The proportions of the septal turbinate formation and the closure of ethmoid sinus cavity were investigated postoperatively by nasal endoscopy in 60 cases with middle turbinate reserved and 60 cases with middle turbinate resected. RESULTS: (1) The morphology and mucosal ultrastructures of reserved middle turbinate were observed to have recovered postoperatively; (2) The proportions of the septal formation and the closure of ethmoid sinus cavity in the groups with middle turbinates reserved and resected were 13.3%, 18.3% and 58.3%, 51.7%, respectively (P < 0.01). CONCLUSION: It is possible that the structure of reserved middle turbinate may return to normal and it is important to save the middle turbinates to improve clinical cure rate.

Adolescent↗

PubMed1999

[Anatomic variations of the ostiomeatal complex and their correlation with chronic sinusitis: CT evaluation].

OBJECTIVE: To explore the relationship between anatomic variations in the ostiomeatal complex (OMC) and chronic sinusitis. METHODS: Coronal plane CT scans of the paranasal sinuses showing the ostiomeatal complex including the middle turbinate, uncinate, ethmoid bulla, agger nasi and Haller cell were analyzed in 297 individuals (594 sides). Statistical analyses were carried out with SPSS 5.0. RESULTS: There were 81.14% of OMC noted to have at least one variation. The anatomic variations included paradoxical curvature of the middle turbinate (13.97%), the pneumatized middle turbinate (34.85%), uncinate hyperplasia(19.36%), deviation of uncinate (45.27%), large ethmoidal bulla (30.30%), large agger nasi (0.70%) and Haller cell (1.00%). The correlation between variations and chronic sinusitis was significant (P < 0.01). CONCLUSION: The occurrence of OMC variation is common. The variations may be one of the causes of chronic sinusitis. Therefore, properly handling the variations was important in the endoscopic sinus surgery.

Adolescent↗

PubMed1999

[Staging of mucous membrane outcome in operative cavity after functional endoscopic sinus surgery].

OBJECTIVE: To investigate the character of transitionary process of mucosa in sinu cavity after functional endoscopic sinus surgery (FESS) and divide it into different stages. METHOD: The morphological character of mucosa in sinus cavity after FESS was surveyed continuously. RESULTS: Over 90% of nasal and sinus cavity got clean within 1 to 2 weeks postoperatively. About 80% of patients had the De-mucous reaction from the 3rd to 10th week, such as mucous edema, vesicles, granulation tissue, mini-polyps, fibrous hyperplasia, and adhesion or regenerated diseases may appear in this stage. All of these diseases competed with mucous epithelization. There were 90% of nasal and sinuous cavity brought to stage of complete epithelization, 11 to 14 weeks were need in about 60% of them. CONCLUSION: Three stages were divided after FESS. They are stage of clean operative cavity, stage of mucous competition and stage of complete epithelization. Proper local care in each stage is essential to the whole curable effect of FESS.

Adolescent↗

PubMed1998

Artificial neural network classification based on capillary electrophoresis of urinary nucleosides for the clinical diagnosis of tumors.

Nucleosides in human urine have been studied frequently as a possible biomedical marker for cancers, acquired immune deficiency syndrome (AIDS) and the whole-body turnover of RNAs. A capillary electrophoretic method that can quantitatively analyze urinary normal and modified nucleosides in less than 40 min with a good resolution and sufficient sensitivity has been developed. Twelve kinds of normal and modified nucleosides were determined in urine samples from 25 healthy persons and 25 cancer patients of 14 kinds of cancers. Artificial neural networks have been used as a powerful pattern recognition tool to distinguish cancer patients from healthy persons. The recognition rate for the training set reached to 100% and above 85% of the members in the predicting set were correctly classified. In addition, the neural network technique was compared with methods of the principal component analysis and the canonical discriminant analysis. The results demonstrate that the predictive ability of the artificial neural network is stronger than the others in this study.

Biomarkers, Tumor↗

PubMed1998

Thymic positive selection and peripheral activation of islet antigen-specific T cells: separation of two diabetogenic steps by an I-A(g7) class II MHC beta-chain mutant.

The diabetes-susceptible class II MHC genes (in human and mouse) share unique nonaspartic acid residues at position 57 of the class II beta-chain. Transgenic expression of a mutant I-A(g7), substituting histidine and serine at position 56 and 57 of beta-chain with proline and aspartic acid (I-A(g7)PD), respectively, inhibits diabetes development in the nonobese diabetic mouse model. Here, we demonstrate that immature thymocytes expressing a diabetogenic islet Ag-specific transgenic TCR are positively selected by I-A(g7)PD class II MHC to give rise to mature CD4+ T cells. However, splenic APCs expressing the same I-A(g7)PD fail to present pancreatic islet Ag to mature T cells bearing this diabetogenic TCR. These results indicate that nonaspartic acid residues at position 57 of class II MHC beta-chain is important for diabetogenic CD4+ T cell activation in the periphery but is not essential for the formation of a diabetogenic T cell repertoire in the thymus.

Amino Acid Substitution↗