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Biomedical subjects

X Chen

Publications and source records attributed to X Chen.

At least 613 records · Page 34Linked to original sources
PubMed2000

[Bacillus subtilis undergoes natural genetic transformation on agar plates].

This paper conducted preliminary investigation on natural genetic transformation of Bacillus subtilis on agar plates. The results showed that, under same conditions, the natural transformation of the strain on agar plate was much more efficient than that of standard liquid method, and the transformation system could sustain higher DNase concentration. In addition, that the LB culture, which usually did not support the strain acquire competency, could undergo transformation as soon as it being spread on agar plate, suggested that the natural genetic transformation of Bacillus subtilis on solid plates may be different form the standard liquid transformation method. The cell-to-cell transformation between strains having different genetic makers could also be observed on agar plates.

Agar↗
PubMed2000

[Production and some properties of a thermophilic protease from Bacillus stearothermophilus WF146].

The factors affecting Bacillus stearothermophilus WF146 for thermophilic protease producing have been investigated, more than 600 units of enzyme in 1 mL of fermented culture could be achieved under suitable condition. The protease had a molecular weight around 34 kD estimated by SDS-PAGE, and functioned optimally at pH 8.0 and 80 degrees C, respectively. In addition, the enzyme exhibited high temperature tolerance and was stable at a wide range of pH, and Ca2+ played a key role for the stability of the enzyme. While the protease activity of the enzyme was strongly inhibited by PMSF, DFP and IAA, and was not affected by DTT.

Endopeptidases↗
PubMed2000

[Development of a system for Polymyxa graminis infection and transmission of wheat yellow mosaic virus].

In growth chambers, a system was developed for infection of Polymyxa graminis to wheat(Triticum aestivum L.), which is an obligate parasite. By the system, the fungus could be propagated in large quantity rapidly and the life cycle of P. graminis in wheat was observed in a period of 13 to 15 days. The methods for separating P. graminis as single cystosori from cultured wheat roots or dried roots were simplified. By tests for the factors affecting on P. graminis infection, including inocula types, seedling age of host plants, temperatures, pH value and nutrient contents etc., the system was modified to more perfection. With an integration of optimal temperature and other elements in the system, which affect on infection and development of P. graminis, wheat yellow mosaic virus (WYMV) was transmitted constantly and efficiently by the fungal vector. In average, 70% of wheat plants inoculated by the viruliferous fungi could infected by WYMV and the typical symptom of wheat mosaic disease would appear at 30 days post-inoculation mechanically.

Ascomycota↗
PubMed2000

[Overproduction and partial characterization of the Ssh7a and Ssh7b proteins from Sulfolobus shibatae].

The Sulfolobus shibatae Ssh7a and Ssh7b proteins have been separately overproduced in Escherichia coli and purified using a simple procedure which includes a heat treatment step. The recombinant and native Ssh7 proteins are similar in the ability to bind both negatively supercoiled and relaxed DNAs. In addition, the recombinant Ssh7a resembles the native Ssh7 protein in constraining negative DNA supercoils. Our data suggest that the two isoforms of Ssh7 interact with DNA in a similar fashion, and the methylation state of Ssh7 interact with DNA in a similar fashion, and the methylation state of Ssh7 does not affect DNA binding and supercoil constraining by the protein.

Archaeal Proteins↗
PubMed2000

[Effect of qiongyugao on the action of DDP in inhibiting the division of GLC-82 cell strain in vitro].

OBJECTIVE: To observe the effect of Qiongyugao (QYG) on the action of DDP in inhibiting the division of GLC-82 cell strain in vitro. METHODS: The method of serum pharmacology was used in observing the morphological change of the cancer cells. By accounting the number of the live cells of each day during 6 days respectively, the growth curve was drawn up. The effects of the three groups on the cancer cells apoptosis of GLC-82 cell strain were analysed by FACS. RESULLTS: The growth of the cancer cells in control group (normal saline) was much better than the other two groups; in chemical therapy group (DDP), the number of the live cells almost kept steady; the number of the live cells in combined group(DDP plus QYG) became even lower. QYG could enhance the action of DDP in inducing the apoptosis of GLC-82 cells strain remarkably. CONCLUSION: QYG can enhance the effects of chemotherapy in inhibiting cancer cells division and inducing their apoptosis.

Adenocarcinoma↗
PubMed2000

New management of angle-closure glaucoma by phacoemulsification with foldable posterior chamber intraocular lens implantation.

OBJECTIVE: To investigate the management of angle-closure glaucoma by phacoemulsification with foldable posterior chamber intraocular lens (PC-IOL) implantation. DESIGN: Retrospective, noncontrolled interventional case series. PARTICIPANTS: In 36 eyes with angle-closure glaucoma (ACG), there were 18 eyes with primary acute angle-closure glaucoma (PACG), 14 eyes with primary chronic angle-closure glaucoma (PCCG), 3 eyes with secondary acute angle-closure glaucoma (SACG) and 1 eye with secondary chronic angle-closure glaucoma (SCCG). INTERVENTION: Phacoemulsification with posterior chamber intraocular lens implantation. MAIN OUTCOME MEASURES: Postoperative visual acuity, IOP, axial anterior chamber depth. RESULTS: After a mean postoperative follow-up time of 8.81 +/- 7.45 months, intraocular pressure was reduced from a preoperative mean of 23.81 +/- 17.84 mmHg to a postoperative mean of 12.54 +/- 4.73 mmHg (P = 0.001). Mean anterior chamber depth was 1.75 +/- 0.48 mm preoperatively and 2.29 +/- 0.38 mm postoperatively (P = 0.000). Best spectacle-corrected visual acuity in 36 eyes ranged from 0.01 to 0.7 (20/200 to 20/30) postoperatively, which was better than preoperative VA ranging from hand movement to 0.4 (20/50) (P = 0.000). CONCLUSION: Phacoemulsification with posterior chamber foldable intraocular lens implantation can be a good alternative in treating angle-closure glaucoma.

Aged↗
PubMed2000

[Clinical observation on the effect of 4% pilocarpine gel used one dose per day in the treatment of glaucoma].

PURPOSE: To compare the efficacy and safety of 4% pilocarpine gel(PG) and 1% pilocarpine solution(PS). METHODS: Twenty cases(40 eyes) with ocular hypertension or primary open angle glaucoma(POAG) in early stage were treated by 4% PG(once per night) and PS(4 times per day). We compared the side-effects and the changes in the intraocular pressure (IOP), pupil size and diopter of 2 groups after medication. Self-control was chosen. RESULTS: The effect of 4% PG on IOP can last 20 hours. The IOP decreasing range of the PG group was from 9.3% to 13.8%, while the PS group was from 12.4% to 16.2%. The decreasing range at 10 AM for four weeks of the PG group was from 11.3% to 17.6% while the PS group was from 17.4% to 19.7%. There is no statistically significant difference between two groups. There are more obvious changes in the pupil size and diopter in the PS group and less complain of blurred vision in the PG group. CONCLUSION: The IOP decreasing effect of 4% PG is comparable with that of 1% PS, but the 4% PG is better than 1% PS as concerning the patient compliance and the side effects. So the 4% PG can be used as a substitute for the 1% PS in the clinic.

Adolescent↗
PubMed2000

[The relationship between tracheotomy and intra-tracheal papilloma progression in children].

OBJECTIVE: To clarify the relationship between tracheotomy and intra-tracheal papilloma progression and introduce the experience of managing dyspnea in the hospital. METHODS: Children who were treated in ENT department of Tongren Hospital between 1992 and 1997 were reviewed in this essay. There were totally sixty-two children (thirty-two boys and thirty girls) with laryngeal papilloma and recurrent respiratory papillomatosis enroled in the series. RESULTS: Among 33 non-tracheotomied children the intra-tracheal lesions were found in only 2 cases (6.1%). There were 17 (80.9%) cases presented intra-tracheal lesions in 21 tracheotomied cases, and it showed great statistical difference (chi 2 = 27.4, P < 0.005). There were no difference of onset age, sex and the first sites of papilloma lesions between the non-tracheotomied and tracheotomied groups(P > 0.05). CONCLUSION: We found papilloma has a week potential to progress into trachea. Tracheotomy is the most important factor of intra-tracheal papilloma progression in many cases. The tracheotomy can be avoided.

Child↗
PubMed2000

[Cholesteatoma of the cerebellopontine angle presented as trigeminal neuralgia].

OBJECTIVE: To explore the effective methods of diagnosis and treatment for cholesteatoma of the cerebellopontine angle presented as trigeminal neuralgia. METHODS: The Clinical data of 13 patients were studied retrospectively. RESULTS: Only 1 case of Cholesteatoma in cerebellopontine and suprasellar cistern was detected with cranial CT scans among 13 patients. Prolonged latency of Wave V and interpeak peak latencies of I-V Wave were recorded in 1 case on auditory brainstem response(ABR). But 9 patients had abnormality in ENG (2 paralysis, 2 paresis). During the operations, we found that cholesteatoma tissue or its capsule wrapped the roots of trigeminal nerves. The cholesteatoma were removed through post-sigmoid sinus approach without partial amputation of trigeminal posterior root. All the patients were clinically cured by extraction of cholesteatoma with following up period of 3 years (10 cases) and half of a year(3 cases). Cholesteatoma extended above tentorium was completely resected with post-sigmoid sinus approach in one case. CONCLUSIONS: ENG is more sensitive than cranial CT and ABR for diagnosis of cholesteatoma in the cerebellopontine angle. The post-sigmoid sinus approach is the best operative approach. It is unnecessary to have the partial amputation of trigeminal posterior root if cholesteatoma can be completely removed. When cholesteatoma extends above tentorium, it can be removed simultaneously by post-sigmoid sinus approach.

Adult↗
PubMed2000

[Determination of the immune function of the erythrocyte and leucocyte and the activity of IL-4 and IFN-gamma in patients with allergic rhinitis].

OBJECTIVE: To investigate the immune function of erythrocyte (RBC) and leucocyte (WBC), and variety of the interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) among patients with allergic rhinitis. METHODS: IL-4 and IFN-gamma secreted by peripheral blood mononuclear cells (PBMC) were measured and compared with immune adhesive and BA-ELISA method. RESULTS: Results showed the RBC and WBC immune adhesive function and IFN-gamma were significantly decreased than of the control, and IL-4 activity were significantly higher than the controls (P < 0.01) in patients with perennial allergic rhinitis. CONCLUSION: These results suggest that RBC and WBC the immune function and IL-4 and IFN-gamma may play an important role in allergic rhinitis.

Adolescent↗
PubMed2000

[Value of preservation of uvula in uvulopalatopharyngoplasty].

OBJECTIVE: To explore the effect of the modified Uvulopalatopharyngoplasty (UPPP) where uvula is preserved in the operation, and whether the postoperative complications are diminished. METHODS: Thirty consecutive patients with the obstructive sleep apnea syndrome (29 men, 1 woman) were analyzed by questionnaire, polysomnography and oral cavity measurement before and 6 months after uvulopalatopharyngoplasty to assess the surgical outcome and value of preservation of uvula in the operation. RESULTS: Eighty-seven percent of patients reported improvement of snoring and daytime sleepiness. Fifty-three percent of patients showed a decrease of at least 50% in the apnea and hypopnea indices. Among the mild and moderate obstructive sleep apnea (AHI < 50), 73.3% of them showed a decrease of at least 50% in the AHI. No velopalatal insufficiency occurred. The result of oral cavity measurement showed that the uvula, which was preserved completely during the operation, began to contract 2 weeks after the operation. Three to six month after operation, uvula contracted to the normal length and the anatomical shape of the pharyngeal cavity became normal. CONCLUSIONS: The results of the uvula preserving UPPP indicate that this approach not only improves the effect of the UPPP, but also avoids the postoperative complications. The uvula that preserved completely during the operation will contract to the normal length progressively.

Adult↗
PubMed2000

[Liver sinusoidal endothelial cell damage during normothermic ischemia and reperfusion of rat].

OBJECTIVE: To observe the damage to liver sinusoidal endothelial cells during normothermic ischemia and reperfusion. METHODS: The afferent vessels of rat liver were clamped for 20, 40, 60 and 90 min respectively. The blood flow to the liver then was restored by removing the clamp. Ultrastructural changes in the sinusoidal endothelial cells in various periods were observed. RESULTS: After 20 or 40 min ischemia, fenestrations of the endothelial cells were enlarged and became mesh-like, but reperfusion for 120 min, led to recovery. After 60 or 90 min ischemia, the sieve plates and cytoplasmic processes of the endothelial cells were destroyed and the perikaryon tended to be desquamated. Reperfusion for 120 min led to no recovery, but resulted in the aggravation of injury and irreversible damage. The liver sinusoids were filled with numerous blood cells and blebs derived from hepatocytes, resulting in circulatory disturbance. CONCLUSIONS: Warm ischemia results in severe endothelial cell destruction. Endothelial cell damages may have unfavorable effects on the microcirculation of the reperfusion liver after prolonged ischemia.

Animals↗
PubMed2000

[Detection of proteolytic activity of hepatitis C virus NS3-4A protease using enzymelinked immunosorbent assay].

OBJECTIVE: To establish an ELISA method for detecting proteolytic activity of HCV serine protease for screening inhibitors against HCV. METHODS: HCV recombinant plasmid pMAL-c2/NS3-4A was transformed into the E. coli strain K12 TB1. Maltose-binding-protein (MBP)-NS3/NS3-4A fusion protein expression were induced by adding isopropyl-beta-D-thiogalacto-pyranoside (IPTG) and purified by affinity chromatography. The immunological activities of the fusion protein were analyzed by Western blot. A peptide substrate was used to analyze the biological activity of the fusion protein. The hydrolyzed product was treated with sodium iodacetate and labeled with digoxigenin, then adding immunological anti-digoxigenin-alkaline phosphatase conjugate to detect the protease activity by colorimeteric reaction. RESULTS: The purified MBP-NS3 and MBP-NS3-4A proteases were identified as 112,000 u and 116,000 u protein by Western blot. HCV NS3/NS3-4A protease showed substrate cleavage activities by ELISA. Coefficients of variation (CV) of ELISA in a lot and among the lots were 4.16% and 7.52% respectively, the P/N was 3.63 under the best experimental conditions determined by L9 (3(4)) factorial design. The method confirmed that 8.36 mumol/L 1,4-naphthoquinone had 50% inhibitive activity on HCV serine protease. CONCLUSIONS: We have established a simple and rapid ELISA method with stable repeatability for detecting proteolytic activities of HCV NS3-4A protease, which might be used for screening and studying of specific inhibitors of HCV serine protease NS3-4A.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

Final report about Stage II Collaboration Project on Leprosy Rehabilitation.

OBJECTIVE: To undertake the pilot experiments of prevention of disability (POD) in 14 different geographical areas to serve as examples for future development of rehabilitation work in China and in Asia. METHODS: According to the principles and national criterion, 27 000 people affected by leprosy were selected and assessed using disability record forms at beginning and followed up regularly for observing changes of different indicators. RESULTS: A total of 197 neuritis cases were detected and treated with prednisolone out of 1 407 new or active cases. Self-care training of eyes, hands and feet were conducted for 10 500 disabled people affected by leprosy. Comprehensive therapy was given to 1 804 cases having complicated ulcers of which 1 055 cases have got their ulcers healed. Out of 706 prostheses, 613 were given to patients with satisfactory results. Surgical treatment was given to 269 cases and 251 have shown good progress. CONCLUSION: Most of patients have got benefit from the project in function or appearance which is very helpful for their going back to the society and agreed by foreign experts during the final evaluation. The experiences from the project can be implemented in the whole country.

China↗
PubMed2000

[Determination of nickel based on the fluorescence quenching of phenanthroline].

A new selective and sensitive spectrofluorimetric method for the determination of trace amounts of nickel in industrial waste water has been developed. This method is based on the quenching of fluorescence of phenanthroline due to the formation of complex Ni (II)-Phen. The exitation and emission wavelengths were found to be 272 and 366 nm, respectively. There was a linear relationship in the range of 10.0-120 ng.mL-1 for Ni. This method is simple and rapid, and has been applied to the determination of nickel in industrial waste water.

Nickel↗