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Biomedical subjects

L Xu

Publications and source records attributed to L Xu.

At least 181 records · Page 10Linked to original sources
PubMed2001

[Changes in the activity of platelet L-arginine/nitric oxide pathway in hypercholesterolemia patients].

OBJECTIVE: To investigate the changes of the platelet L-arginine (L-Arg)/nitric oxide (NO) pathway in hypercholesterolemia patients. METHODS: The platelet NO production in 21 hypercholesterolemia (HC) patients and 26 normal individuals was assayed by spectrum, the NOS activity and the transportation of L-Arg were determined by (3)H-labelled L-Arg. RESULTS: The NO production in hypercholesterolemic platelets [(24.06 +/- 3.70) nmol/10(8) platelets] was decreased significantly as compared with normal controls [(28.39 +/- 4.45) nmol/10(8) platelets] (P < 0.01), and so did the NOS activity [(1.46 +/- 0.47) pmol/10(8) platelets] vs (1.81 +/- 0.50) pmol/10(8) platelets]. The transportation of L-Arg by hypercholesterolemia platelets also decreased significantly than that by normal controls. The Vmax in the former [(46.84 +/- 3.39) pmol x (10(7) platelets)(-1) x min(-1)] was significantly lower than that in the latter [(53.89 +/- 3.45) pmol x (10(7) platelets)(-1) x min(-1)]. There was no difference between the two groups in K(d) (P > 0.05). CONCLUSIONS: The activity of the L-arg/NO pathway in hypercholesterolemia platelets is decreased significantly as compared with normal controls, implying that it is probably one of the reasons for the hyperactivity of hypercholesterolemia platelets.

Adult↗
PubMed2001

[Trends of underline diseases of pulmonary embolism from Peking Union Medical College Hospital].

OBJECTIVE: To highlight the understanding of pulmonary embolism(PE), and analyze the trends of underline diseases of PE from Peking Union Medical College(PUMC) Hospital in the last half century. METHODS: 239 cases of PE were reviewed retrospectively from 1950 to 2000 in PUMC Hospital. RESULTS: In the first and second periods (1950-1982, 1983-1990), about 3 cases of PE were diagnosed annually, but in the third (1991-1997) and fourth periods (1998-2000), 8 cases and 20.6 cases of PE were found annually. The incidence of underline diseases of PE, such as deep venous thrombosis (DVT), cardiac disease, malignancy and connective tissue disease varied in different periods. The morbidity of DVT with PE was dramatically enhanced recently. CONCLUSION: There is an increasing trend of incidence of PE in the last half century. DVT events become the most common underline disease or risk factor of PE.

Adolescent↗
PubMed2001

[A computer-aid study on the craniofacial features of Archang race in Yunnan province of China].

OBJECTIVE: Archang race is one of special minoritis in Yunnan province of China. However, there is not former report about overall craniofacial features in Archang race, therefore a computerized measurement on craniofacial features of Archang race was established in this study. METHODS: On the basis of the principles of random sampling, the craniofacial features of 196 normal adults of Archang race coming from Longchuan County, Dehong Dai Jingpo nationality autonomous prefecture in Yunnan province of China were investigated using the craniofacial video-computerized measurement system which was developed by us. RESULTS: Totally 41 measured items and 17 indexes of craniofacial features were obtained from male and female adults of Archang race. On the basis of 5 indexes, the people were classified according to the head, facial, and nose forms. CONCLUSION: The results of this study are of great importance in terms of that the reference is not only significant for anthropology, ethnology, but also for medicine and industry.

Aged↗
PubMed2001

[The influence of palatoplasty and tympanotomy on middle ear function in cleft palate patients].

OBJECTIVE: The aim of this study is to explore the influence of palatoplasty and tympanotomy on middle ear function or hearing condition in cleft palate patients. METHODS: A total of 22 ears with otitis media with effusion in cleft palate patients were inserted with PE tubes, and Pre- and post-operative hearing level and middle ear function in these patients were tested and compared respectively, in order to demonstrate the action of tympanotomy and PE insertion on hearing and middle ear function. Another 38 patients with cleft palate were operated in their early age with the proper operation method, and pre- and post-operative middle ear function were examined and compared to show the influence of the operation on the middle ear function. RESULTS: PE Tube insertion and tympanotomy changed the pressure condition of middle ear cavity and raised the hearing level about 17 dB in the middle-ear-diseased cleft palate patients, and patients with palatoplasty did not show obvious changes in middle ear function in the short-term trail. CONCLUSION: Early and active tympanotomy do help in improving the function of the middle ear, and it is suggested to improve patients' hearing and middle ear function as early as possible. Palatoplasty did not affect the function of middle ear.

Cleft Palate↗
PubMed2001

[Determination of the point of gene mutation in two types of tissue from the aminoglycoside antibiotics induced deaf patients].

OBJECTIVE: To elucidate the gene mutation presents in hair follicle cells, just as blood cells, in the aminoglycoside antibiotics induced deaf patients(AAID). METHOD: Mitochondrial DNA of blood cells and/or hair follicle cells from 8 members of 3 aminoglycoside antibiotics induced deafness families were analysed using PCR-SSCP and Alw 26 I digestian. RESULT: Our result showed that a gene mutation at nucleotide 1555 in 12 S rRNA of mitochondrial DNA appeared in blood cells and/or hair follicle cells of 7 subjects among those 8 members. Only a father with normal hearing did't exhibit such a mutation. CONCLUSION: This indicated that hairs could be used as a sample instead of blood to perform gene examination for AAID.

Aminoglycosides↗
PubMed2001

[The therapy of children with secretory otitis media by myringotomy with grommet insertion and the relevant management].

OBJECTIVE: To improve the diagnosis and treatment level of secretory otitis media (SOM) of children. METHOD: Clinical information of 80 children with SOM were collected and analysed. All of the 80 cases (144 ears) were treated by myringotomy with Grommet insertion. Among them 30 cases by adenotonsillectomy. 10 cases by palatoplasty. Secretions of 54 ears were carded out by bacterial culture. RESULT: 80 cases were followed up for 6 to 12 months. 120 ears of 144 were cured(83%), with hearing improved. The tympanograms and hearing threshold of pure tone were found to be normal. The Gram's positive and negative germs of bacterial culture were 20.7% (6/29 samples) and 24% (6/25 samples) respectively. CONCLUSION: Children with secretory otitis media should be treated as early as possible to improve the patients' hearing and develope their speech.

Child↗
PubMed2001

[Study of the adsorption properties in chromatographic separation of the citric acid].

A new method studying the change of thermodynamic properties at different temperatures to screen suitable stationary phases for chromatographic separation of the citric acid (CA) on an analytical column has been developed. The applied method is mainly based on using CA with a series of solute concentrations (0 g/L-250 g/L) as mobile phase to seriously overpass the unloaded stationary phase to find the breakthrough curves of CA. The adsorption isotherms were calculated from the retention times of breakthrough curve. The bed porosity of column was calculated from the elution time of a peak of the blue dextran as non-adsorbed tracer. The stationary phase, which has been selected through this method, for the separation of CA from fermentation broth, showed a very high adsorption capacity for CA, even under very low concentrations, so it can even be used in the separation and purification process of minute amounts of CA. The separation effect of this stationary phase for citric acid can be greatly enhanced through the technique of change of temperature. This new separation process can shorten the old process path, improve the yield of finished products more than 10%, and reduce the cost more than 10%. At the same time, the pollution of the production of citric acid can be reduced. It turned out that this method will play an important role in the synthesis of stationary phase for the separation of citric acid and the study of its structure.

Adsorption↗
PubMed2001

[Advancement in mechanisms of long-term potentiation].

Synaptic plasticity in mammalian brain is one of the most widely studied topics in neuroscience over the last decade. Long-term potentiation (LTP), mainly involving post-synaptic mechanisms, is a reflection of neural plasticity. Study on the mechanisms of LTP was formerly focused on the properties of NMDA receptor and the intracellular cascade of reaction after activation of the receptor. However, the definition of "silent synapses" with only NMDA receptors without AMPA receptors was frequently referred in LTP study, showing the importance of AMPA receptor in post-synaptic mechanism of LTP.

Animals↗
PubMed2001

[Study on the application of quantitative analysis of cell-wall amino acids in actinomycetes classification].

This paper has collected 70 recognized type strains of actinomycete from home and abroad Microbiological culture collection centers. Adopting thin-layer chromatography and thin-layer chromatogram scanner methods to quantitatively analyze the composition of cell-wall amino acids in actinomycete. It has made comparison between quantitative results and qualitative ones. After a thorough discussion, a revision is made on the standard of dividing cell-wall types in actinomycete chemical classification, which has provided some original suggestion in hope of improving the research of actinomycete chemical classification.

Actinobacteria↗
PubMed2001

[Studies on transference of hydrogenase genes of Rhizobium arachis].

The hydrogen-uptake genes were transferred into wild Rhizobium arachis Ra strains (Hup-, Nif+, Apr) by triparental mating using pRK2013 as help plasmid. A transconjugant R. arachis Rz34-2(Hup+, Nif+, Apr, Tcr) which expressed high activities of hydrogenase and nitrogenase under free-living and symbiotic state was screened. Peanut inoculation test with recipient R. arachis Ra34, transcojugant Rz34-2 and control strain R. arachis L8-3 (Hup+, Nif+) was carried out respectively. The results showed that, compare to treatment without inoculation, inoculation with R. arachis Ra34 and R. arachis L8-3, the dry weight of leaf inoculated with transconjuant Rz34-2 increased 6.2%, 7.6% and 6.3% respectively; the N-content of seed increased 8.8%, 10.0% and 6.0%; the output increased 18.8%, 10.5% and 10.7%. This suggested that legume plants inoculated with Rhizobium strains (Hup+) were more efficient to accumulate N and to increase its output.

Arachis↗
PubMed2001

A study on the preservation of fresh amniotic membrane.

OBJECTIVE: To establish the standard preservation methods of fresh amniotic membrane for clinical use. METHODS: Human placentas were collected aseptically from selective caesarean sections in normal women in time. Amniotic or placental membrane were peeled and preserved in N. S, P. B. S or DMEM at 4 degrees C or cultured in DMEM at 37 degrees C, 5% CO2. Trypan-blue staining, light and electronic microscopy were observed every six hours after preservation. RESULTS: Seventy percent of amniotic epithelial cells survived after preservation in N.S for 6 hours, PBS 12 hours, DMEM 24 hours and 1 week in tissue culture. The amount of living epithelial cells maintained in placental membrane preservation was less than that in amniotic membrane preservation at the same time (t-test, P < 0.01). No collagen degeneration was found during preservation. CONCLUSION: Preservative solution and time will affect the maintenance time of fresh amniotic membrane greatly. Fresh amniotic membrane should be preserved within 6 hours in N. S, 12 hours in P. B. S, 24 hours in DMEM at 4 degrees C and 1 week in tissue culture for clinical use.

Adult↗
PubMed2001

[Comparing cryopreserved with fresh corneas on clinical application in penetrating keratoplasty].

PURPOSE: To evaluate the role of cryopreserved corneas on penetrating keratoplasty (PKP) by comparing them with fresh corneas on clinical application. METHODS: Third-six excellent condition patients were chosen and randomly divided into two groups. They were performed PKP by using fresh and cryopreserved corneas respectively. The graft transparency, epithelial healing speed of graft, tear membrane, graft thickness, endothelium density and visual acurity were emphasized respectively. RESULTS: When fresh and cryopreserved corneas were used on PKP as the donor respectively, postoperative time to recover normal break-up time (BUT) was two to six months average (4.7 +/- 0.3) months and two to eight months, average (5.6 +/- 0.4) months and time to recover normal Schirmer's test was one to four months average (2.1 +/- 0.3) months and 1-3.5 months, average (1.7 +/- 0.5) months. The graft's thickness, stabilized visual acurity and graft's rejective rate were 0.56-0.68 mm (average 0.62 mm) vs 0.54-0.62 mm (average 0.59 mm), (0.46 +/- 0.03) vs (0.44 +/- 0.05) and 20% vs 19% respectively when fresh vs cryoperserved corneas. No statistical significance between fresh and cryopreserved corneas (P > 0.05). But the grafts behaved intact epithelium and continuing transparency when fresh corneas as donors, while the graft's epithelial defects healed after three to five days of the operation and edematous grafts were reclear after two to three weeks of the operation when cryopreserved corneas as donors. Graft's endothelium density in fresh corneas group 2,043-2,210 cells/mm2 (average 2,135 cells/mm2) was high than in cryopreserved corneas 1,240-1,860 cells/mm2 (average 1,672 cells/mm2) (P < 0.01). CONCLUSION: There were no statistical significance on the transparent rate of grafts, grafts thickness, visual acurity and graft's rejective rate between fresh and cryopreserved corneas. But graft's epithelium healing was delayed and endothelium density was lower when cryopreserved corneas as donors.

Adolescent↗
PubMed2001

[Clinical study on effect of qihuang oral liquid to enteric flora disturbance and serum endotoxin level in patients of liver cirrhosis].

OBJECTIVE: To study the effect of Qihuang oral liquid (QHOL) in treating enteric flora disturbance and serum endotoxin level of liver cirrhosis patients. METHODS: Seventy patients suffering from liver cirrhosis were randomized into the control group and the QHOL treated group. The symptomatic changes, quantitative determination of anaerobic and aerobic flora in feces as well as serum endotoxin level were observed before and after treatment. RESULTS: In comparison with the control group, the treated group revealed a significantly better effects (P < 0.05) in the following parameters: (1) reduction in aerobic and increase in anaerobic flora, thus to improve the ratio of enteric flora; (2) improvement in clinical symptoms; (3) lowering in serum endotoxin level. CONCLUSION: QHOL might alter the ratio of enteric flora by increasing anaerobics, a significant lowering of enterogenic endotoxin production and absorption, hence obviously reduced serum endotoxin level was induced which might correlate to the improvement in symptoms and liver damage.

Adult↗
PubMed2001

[Synthesis and anticancer activity of 3-[(3'-methyl-4'-(substituted phenyl)-1',3'-butadienyl] indole derivatives].

AIM: To study the synthesis and anticancer activity of 3-[(3'-methyl-4'-(substituted phenyl)-1',3'-butadienyl] indole derivatives. METHODS: Electrophilic-substitution, aldol-condensation, selective-reduction, phase-transfer Wittig reaction and hydrolysis reaction were used in the synthesis of the title compounds. RESULTS: Eleven compounds of 3-[(3'-methyl-4'-(substituted phenyl)-1',3'-butadienyl] indole were synthesized. They are new compounds. Compound 8 showed different inhibitory effects on HL-60, HCT-8 and Bel7402 cell lines in vitro, and its inhibitory rate of antiinflammation was 100% at 10(-5) mol.L-1 concentration. CONCLUSION: Compound 8 showed high anticancer and antiinflammatory activities, and is worth further studying.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

[Synthesis and biological activity of 2-[(substituted phenyl)vinyl] indole derivatives].

AIM: To synthesize derivatives of 2-[substituted phenyl)vinyl] indole and find compounds with biological activities by screening in vitro. METHODS: Twenty-one compounds of 2-[(substituted phenyl) vinyl] indole were synthesized by reduction, oxidation and Witting reaction. MS, 1HNMR and elemental analysis were used to determine the structures of the new compounds. RESULTS: These compounds are new ones. CONCLUSION: Six compounds (3, 9, 11, 13, 18 and 20) showed effects on some different receptors, such as alpha 2, D2 and H1, and is worth further studying.

Animals↗
PubMed2001

[Effect and mechanism of securinine on synaptic transmission in the dentate gyrus of anesthetized rats].

AIM: To study the effects of (+) and (-) securinine on the basic synaptic transmission and long-term potentiation (LTP) induced by high-frequency stimulation in the dentate gyrus of anesthetized rats and its possible mechanism. METHODS: The population spike (PS) was recorded by electrophysiological techniques. RESULTS: The results showed that at the concentration of 2 x 10(-9) mol.L-1, (+), (-) securinine showed no effect on either the basal PS or LTP. At high cocentrations (2 x 10(-8), 2 x 10(-7) mol.L-1), (+), (-) securinine not only potentiated the basal PS but also enhanced the magnitude of LTP. (+), (-) Securinine showed similar effects; and the effects were completely inhibited by the inhibitory amino acid GABA. CONCLUSION: These results suggest that the effects of (+), (-) securinine on induction and maintenance of LTP may be related to its blockade of GABA receptor.

Alkaloids↗