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Biomedical subjects

L Xu

Publications and source records attributed to L Xu.

At least 307 records · Page 17Linked to original sources
PubMed2000

[Purification of soluble egg antigen (SEA) 38 kDa molecule of Schistosoma japonicum and preliminary evaluation of its immunodiagnostic efficacy].

OBJECTIVE: To study the applicability of soluble egg antigen (SEA) 38 kDa molecule of Schistosoma japonicum in the immunodiagnosis of schistosomiasis. METHODS: The target immunodiagnositic antigen SEA 38 kDa molecule was separated and purified by SDS-PAGE and electroelution technique and evaluated by SDS-PAGE and Western blotting. To compare their immunodiagnostic efficacy, the purified SEA 38 kDa and SEA were used to examine the sera from 182 cases including 31 acute schistosomiasis patients, 31 chronic schistosomiasis patients, 60 normal human controls, 30 paragonimiasis patients and 30 clonorchiasis patients. RESULTS: The positive rates of purified SEA 38 kDa and SEA for acute schistosomiasis patients, chronic schistosomiasis patients, normal human controls, paragonimiasis patients and clonorchiasis patients were 90.3%, 90.3%, 1.7%, 0, 0 and 90.3%, 83.9%, 3.3%, 0, 0, respectively. The P/N ratio of purified SEA 38 kDa and SEA in immunodiagnosis of schistosomiasis by ELISA had been compared by two-sample t-test. It was demonstrated that there existed significant differences between purified SEA 38 kDa and SEA in the three groups of acute and chronic schistosomiasis patients and normal persons(P < 0.001). The P/N ratio of SEA 38 kDa in detecting the sera from schistosomiasis patients was obviously higher than that of SEA, but when SEA 38 kDa was used to examine normal human sera, the result was converse. CONCLUSION: The purified SEA 38 kDa has higher sensitivity and specificity and immunodiagnostic potential.

Animals↗
PubMed2000

[Pharmacognostical studies on the roots of Stellera chamaejasme and S. chamaejasme f. chrysantha].

Morphological and histological characters of the roots of Stellera chamaejasme L. and S. chamaejasme L. f. chrysantha S. C. Huang, used as the origins of the Chinese medicine Langdu, were described and illustrated with line drawings. TLC analyses of the above two drugs were also undertaken. These studies provide referencial informations for the quality control, development and identification of these two drugs.

Chromatography, Thin Layer↗
PubMed2000

[Pharmacognostical studies on the roots of Euphorbia fischeriana].

Morphological and histological characters of the roots of Euphorbia fischeriana Steud., used as one of the origins of traditional Chinese medicine Langdu, 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↗
PubMed2000

[The study on Rhizoma Alpiniae officinarum and other herbs as penetration enhancer for the permeation of 5-fluorouacil].

OBJECTIVE: To study the effects of volatile oils from Rhizoma Alpiniae Officinarum, Pericarpium Zanthoxyli, Herba Asari, cineaol and ethanol extracts on the percutaneous pentration of 5-fluorouracil. METHODS: By Valia-Chienhorizontal diffusion cell and HPLC, the effects of volatile oils from Rhizoma Alpiniae Officinarum, Pericarpium Zanthoxyli, Herba Asari, cineol and ethanol extracts on the percutaneous penetration of 5-fluorouracil were observed and compared with azone. RESULT: 1%, 3% volatile oils from Rhizoma Alpiniae Officinarum, Pericarpium Zanthoxyli and cineol possessed strong promoting action on percutaneous absorption of 5-fluorouracil. The effects of volatile oils from Rhizoma Alpiniae Officinarum was stronger than that of azone; the effects of volatile oils from Pericarpium Zanthoxyli was the same as that of azone. CONDUSION: The volatile oils from Rhizoma Alpiniae Officinarum, Pericarpium Zanthoxyli, Herba Asari can enhance effectively the skin permeation of 5-fluorouracil. They deserved to be researched and developed further.

Administration, Cutaneous↗
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

[Effect of reperfusion after local ischaemia on the M receptor density in rat brains].

OBJECTIVE: To study the dynamic changes in the density of muscarinic acetylcholine receptor in different areas of rat brains during reperfusion after local ischaemia. METHODS: The rat cerebral focal ischemia/reperfusion model after middle cerebral artery occlusion was made by the intraluminal suture method. Using 3H-QNB as radioligand, after binding with M receptor on the brain slice of the rat model, the brain samples were exposed on the hypersensitive film [H-3] to complete autoradiography, and the density of M receptor in different areas on the film of autoradiography was measured. RESULTS: There were no changes in the M receptor density in 2 hours' ischaemia group and 2 hours' reperfusion group, M receptor densities in the area of occipital cortex (OC) and temporal cortex (TC) were observed to decrease significantly in 8 hours' reperfusion group, but the degree of decrease was lower than 24 hours' and 72 hours' reperfusion groups, there was significant decrease in the density of M receptor in the areas of caudate putamen (CP), frontal cortex (FC), TC, OC of the 24 hours' and 72 hours' reperfusion groups and no difference was found between these two groups, and the imaging of M receptor in the domains with decreased receptor was obvious. CONCLUSIONS: The quantity of M receptor did not change right after ischaemia or reperfusion. It decreased gradually after an interval of time; Imaging of the M receptor could assess the changes of the density of viable cholinergic neurons and be a marker of diagnosis, therapy, and prognosis of brain ischaemia.

Animals↗
PubMed2000

[Surgical treatment of malignant esophageal tumors in PUMC Hospital].

OBJECTIVE: To study how to prolong the postoperative survival time of the patients with malignant esophageal tumors. METHODS: The clinical data of 1,098 patients with malignant esophageal tumors from 1961 to 1992 were retrospectively analyzed. The deletion of fragile histamine triplet(FHIT) gene(a tumor suppressor gene) in 30 fresh esophageal samples obtained in 1996 was detected with PCR and RT-PCR. RESULTS: The resectability was raised gradually and the operative morbidity and mortality decreased year-by-year, but there was no significant improvement on the postoperative 5-year survival rate. Delayed diagnosis and ir-radical resection influenced the long term survival. The deletion of cDNA of FHIT gene was 64.2% in esophageal cancer and 20% in the resected margin of the cancer. CONCLUSIONS: High atypical hyperplasia in esophageal epithelium and deletion of FHIT gene in esophageal cancer and its resected margin are pathological and molecular markers for early diagnosis of esophageal cancer respectively, and the latter may be one of the molecular markers for the resection. Early diagnosis and treatment, radical resection, and postoperative nutritional support are essential for the improvement of the postoperative survival time of the patients.

Acid Anhydride Hydrolases↗
PubMed2000

[Chemical constituents of annonaceae plants and their antitumor activities].

This report is the summary of our research on the chemical constitutents and their antitumor activities of Annonaceae plants. Annonaceous acetogenins, polyoxy-cyclohexenoids, and styryl-lactones from Annonaceae are the main constituents of antitumor activities. They are expected to develop a kind of new antitumor medicines.

Annonaceae↗
PubMed2000

[Bone mineral density and exercises: a cross-sectional study on Chinese athletes].

OBJECTIVES: To evaluate the effect of exercise to osteoporosis by bone mineral density (BMD) measurement of athelets comparing normal individuals in general population. METHODS: BMD of radium, lumber spine, and femoral neck were measured by single photon absorptiometry (SPA), quantitative CT (QCT), and dual X-ray absorptiometry (DXA) respectively in athletes (n = 162, male 79, female 83) and age matched non-athletes normal population (n = 204, male 91, female 113) in Beijing. RESULTS: BMD of all sites in all age groups of both male and female athletes are significantly higher comparing with that in non-athletic population. This predominance in athletes is even more distinctive in peak bone mass. Peak bone mass of male athletes is significantly higher than that of female athletes. Bone loss with age is less apparent in athletes than in control. However, there is an accelerated decline of BMD in lumber spine and femoral neck in 30-39 year age group in both male and female athletes, which may be due to the wanting of physical exercise. CONCLUSIONS: Long term regular proper exercise started in adolescence may play a very important role in the prevention of osteoporosis by improving peak bone mass and decreasing bone loss.

Absorptiometry, Photon↗
PubMed2000

[A reflection interference method for determining optical constants and thickness of a thin solid film].

In this paper we report a simple method for deducing optical constants and thickness from the reflection interference spectrum of a thin transparent film which is on a substrate of high reflection coefficient. When a light beam is incident on the surface of the film, the reflection light beams at the front and rear faces are coherent. We calculated the optical constants and thickness of the film from the reflection spectrum. This simple method makes a directly programmable calculation possible.

English Abstract↗
PubMed2000

[Clinical evaluation of the paste of erythromycin ethylsuccinate-metronidazole CP for root canal sterilization].

OBJECTIVE: The infected root canal was sterilized by anti-bacteria compound paste and the efficacy was compared with FC. METHODS: According to the mixed infection in infected root canal of anaerobic bacteria and obligate anaerobe, the paste made of erythromycin ethylsuccinate, metronidazole and CP was selected to seal and sterilize the root canal. RESULTS: The clinical observation of 180 patients with entirely developed root apex of acute and chronic apical periodontitis shown that there was no significant difference comparing erythromycin ethylsuccinate metronidazole-CP with FC in root canal sterilization, therefore, the irritability and poisonousness of the paste can be reduced by using erythromycin ethylsuccinate metronidazole CP instead of FC. CONCLUSION: The root canal sterilization drug of erythromycin ethylsuccinate metronidazole-CP was a safe and effective method to promote the restoration of root apex diseases.

English Abstract↗
PubMed1999

Overexpression of bcl-2, bcl-XL or hsp70 in murine cortical astrocytes reduces injury of co-cultured neurons.

Astrocytes perform many functions that protect neurons during stress, including transmitter uptake, metabolic support, and protection from oxidative stress. We asked whether astrocytes overexpressing either the anti-apoptotic genes bcl-2, or bcl-XL, or the inducible heat shock protein hsp70, could better protect neurons grown with them in co-culture than normal astrocytes or astrocytes expressing beta-galactosidase. Retroviral vectors were used to express these genes in primary astrocyte cultures. After antibiotic selection to eliminate untransformed astrocytes, neurons were plated on top of the astrocytes. Overexpression of any of the three genes in astrocytes reduced neuronal injury induced by combined oxygen-glucose deprivation, or glucose deprivation. Hsp70 overexpression reduced glutamate toxicity. As none of the genes studied is thought to be secreted, the likeliest explanation for the protection observed is improved astrocyte function.

Animals↗
PubMed1999

Transferrin-liposome-mediated systemic p53 gene therapy in combination with radiation results in regression of human head and neck cancer xenografts.

The use of cationic liposomes as nonviral vehicles for the delivery of therapeutic molecules is becoming increasingly prevalent in the field of gene therapy. We have previously demonstrated that the use of the transferrin ligand (Tf) to target a cationic liposome delivery system resulted in a significant increase in the transfection efficiency of the complex [Xu, L., Pirollo, K.F., and Chang, E.H. (1997). Hum. Gene Ther. 8, 467-475]. Delivery of wild-type (wt) p53 to a radiation-resistant squamous cell carcinoma of the head and neck (SCCHN) cell line via this ligand-targeted, liposome complex was also able to revert the radiation resistant phenotype of these cells in vitro. Here we optimized the Tf/liposome/DNA ratio of the complex (LipT) for maximum tumor cell targeting, even in the presence of serum. The efficient reestablishment of wtp53 function in these SCCHN tumor cells in vitro, via the LipT complex, restored the apoptotic pathway, resulting in a significant increase in radiation-induced apoptosis that was directly proportional to the level of exogenous wtp53 in the tumor cells. More significantly, intravenous administration of LipT-p53 markedly sensitized established SCCHN nude mouse xenograft tumors to radiotherapy. The combination of systemic LipT-p53 gene therapy and radiation resulted in complete tumor regression and inhibition of their recurrence even 6 months after the end of all treatment. These results indicate that this tumor-specific, ligand-liposome delivery system for p53 gene therapy, when used in concert with conventional radiotherapy, can provide a new and more effective means of cancer treatment.

Animals↗
PubMed1999

Adenosine inhibits a non-inactivating K+ current in bovine adrenal cortical cells by activation of multiple P1 receptors.

1. Bovine adrenal zona fasciculata (AZF) cells express a non-inactivating K+ current (IAC) that sets the resting potential while it is activated by intracellular ATP. In whole-cell patch clamp recordings from bovine AZF cells, we found that adenosine selectively inhibited IAC by a maximum of 78.4 +/- 4.6 % (n = 8) with an IC50 of 71 nM. The non-selective adenosine receptor agonist NECA effectively inhibited IAC by 79.3 +/- 2.9 % (n = 24) at a concentration of 100 nM. 2. Inhibition of IAC was mediated through multiple P1 adenosine receptor subtypes. The A1-selective agonist CCPA (10 nM), the A2A-selective agonist CGS 21680 (100 nM) and the A3-selective agonist IB-MECA (10 nM) inhibited IAC by 64.8 +/- 8.4, 78.4 +/- 4.6 and 69.3 +/- 6.9 %, respectively. 3. Specific adenosine receptor subtype antagonists including DPCPX (A1), ZM 241385 (A2A) and MRS 1191 (A3) effectively blocked inhibition of IAC by adenosine receptor-selective agonists. 4. A mixture of the three adenosine receptor antagonists completely suppressed inhibition of IAC by adenosine, but failed to alter inhibition by external ATP which acts through a separate P2 nucleotide receptor. 5. Inhibition of IAC by adenosine or NECA was eliminated by substituting GDP-beta-S for GTP in the pipette, or by replacing ATP with AMP-PNP or UTP. 6. In addition to inhibiting IAC, adenosine (10 microM) depolarized AZF cells by 46.2 +/- 5.8 mV (n = 6). 7. These results show that bovine AZF cells express at least three adenosine receptor subtypes (A1, A2A, A3), each of which is coupled to the inhibition of IAC K+ channels through a G-protein-dependent mechanism requiring ATP hydrolysis. Adenosine-mediated inhibition of IAC is associated with membrane depolarization. Adenosine and other purines may co-ordinate the stress-induced secretion of corticosteroids and catecholamines from the adrenal gland.

Adenosine↗