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Biomedical subjects

S Li

Publications and source records attributed to S Li.

At least 325 records · Page 18Linked to original sources
PubMed2001

[Effect of plastic film mulching on crop yield and nitrogen efficiency in semiarid areas].

The effect of plastic film mulching, water storage in soil profile before sowing, and nitrogen fertilization on crop yield and nitrogen efficiency was examined in this paper. The study site was on the cultivated lossial soil in semiarid areas with 415 mm of annual rainfall and the test crop was spring wheat, Triticum aestivum. In order to study the effect of plastic film mulching, 4 levels of mulching were designed, including mulching of 0, 30 and 60 days after sowing and mulching over the whole growing period. The results showed that increase of soil water storage, plastic film mulching and nitrogen fertilization increased crop yield significantly(alpha < 0.01), and their effect followed in the order of nitrogen fertilization > increase of water storage > plastic film mulching. The effect of mulching on crop yield varied with water storage, nitrogen fertilization and mulching periods. When the water storage was low, there was no significant difference in crop yield between mulching and no mulching, although mulching increased crop yield slightly, and the nitrogen efficiency was higher for no mulching and mulching 30 days. When the water storage was high, the difference between the yield of mulching 60 days and no mulching was significant, but no difference in nitrogen efficiency was found for mulching 30 days, 60 days and over whole growing period. It was suggested that mulching over whole growing period was of less significance in practice.

Crops, Agricultural↗
PubMed2001

[A study on beta-lactamase activity of biofilm Escherichia coli].

OBJECTIVE: To investigate the mechanism of drug resistance of biofilm escherichia coli. METHODS: The model of escherichia coli biofilm was established with the flat-board method. And the biofilm was confirmed by scanning electron microscopy. The beta-lactamase activities were quantitated, in escherichia coli, biofilm escherichia coli, biofilm escherichia coli induced by impenem or cefoxitin. RESULTS: The beta-lactamase activity of biofilm escherichia coli was 2.16 times as much as that of escherichia coli planctonically, and the beta-lactamase activities of biofilm escherichia coli induceded by impenem or cefoxitin were 1.30 and 1.05 times as much as those of biofilm escherichia coli, respectively. CONCLUSION: The drug resistance to antibiotics of biofilm escherichia coli was related to the production of beta-lactamase.

Anti-Bacterial Agents↗
PubMed2001

[Antitumor effects of cytosine deaminase and HSV-tk double suicide gene with adenovirus mediation on rectal cancer cells].

OBJECTIVE: To study antitumor effects of cytosine deaminase (CD) gene/5-fluorocytosine (5-FC) and herpes simplex virus thymidine kinase(HSV-tk) gene/ganciclovir (GCV) systems on rectal cancer cells with adenovirus mediation. METHODS: CD and HSV-tk double suicide genes were transinfected into HR-8348 rectal cancer cells with recombinant adenovirus mediation. The expression of CD and HSV-tk genes was detected with RT-PCR. Plating efficiency and MTT method were used to evaluate the antitumor effect of CD and 5-FC, HSV-tk and GCV systems. RESULTS: Adenovirus was recombined with pAdCMV-Link1(CD + tk), pAdCMV-Link1(-), pAdCMV-Link1(CD), and pAdCMV-Link1(tk) plasmids respectively. HR-8348 cells were infected with the recombined adenovirus and the high expression of CD and (or) HSV-tk genes was found in the corresponding group of tumor cells. Before use of prodrug 5-FC and GCV, the plating efficiency and survival rate of the cells in each group were without significantly different (P > 0.05). But the plating efficiency and survival rate of the tumor cells in pAdCMV-Link1(CD + tk) transinfection group were more highly inhibited than in control, pAdCMV-Link1(-) (P < 0.01) and single suicide gene transinfection groups (P < 0.05) after use of 5-FC and GCV. Combined of use CD and 5-FC, HSV-tk and GCV systems remarkably inhibited the plating efficiency and growth of tumor cells transinfected with double suicide genes. CONCLUSION: Transinfection of CD and HSV-tk double suicide genes has a powerful antitumor effect.

Adenoviridae↗
PubMed2001

[Muscle pigment epithelium-derived factor gene associating with tumorigenesis of B16 melanoma].

OBJECTIVE: Random amplified polymorphic DNA (RAPD) analysis was used to detect the genomic variant in B16 melanoma, and to seek the tumor related DNA fragments. METHODS: Genomic DNA from B16 melanoma and C57BL/6J mouse normal tissues were amplified by RAPD with 105 random primers, the significantly different DNA fragments were isolated, cloned and sequenced. DNA sequences were analyzed with GenBank data. RESULTS: 24 of the 105 primers generated polymorphic profiles when the B16 melanoma RAPD profile was compared to that of its normal tissue DNA. By amplification of the primer AB8-5, a tumor band showing loss with respect to normal band was detected and this DNA fragment was designated as B8-5. B8-5 was a 610 bp fragment, the sequencing result of B8-5 showed 99% homology with muscle pigment epithelium-derived factor (PEDF) gene, and 100% homology with muscle pigment epithelium-derived factor mRNA. B8-5 was therefore regarded as PEDF gene. CONCLUSION: Our result found that allelic losses exist in PEDF gene, and therefore suggest that PEDF is associated with tumorigenesis of B16 melanoma.

Alleles↗
PubMed2001

[The assay of beta-lactamase activity in Pseudomonas aeruginosa biofilm].

OBJECTIVE: To analyze the resistance mechanism of Pseudomonas aeruginosa biofilm bacteria. METHODS: An in vitro model of Pseudomonas aeruginosa bacterial biofilm was established in silicon disk with modified flat-board method and a rapid staining procedure of AgNO3 was used to verify it. Biofilm was observed under scanning electron microscopy. The test was carried out in three groups. Group A was planktonic bacteria of Pseudomonas aeruginosa, group B biofilm bacteria of Pseudomonas aeruginosa and group C biofilm bacteria induced by imipenem. The activity of beta-lactamase was quantitated with a spectrophotometric assay method and beta-lactamase quantitation was determined by using Bio-Rad protein assay. RESULTS: The activity and protein content of beta-lactamase in group B was higher than that in group A by 4.67 and 2.09 times. The activity of group C was 21.86 times as much as that in group A and 4.68 times as much as that in group B. The quantitation in group C was 6.28 times as much as that in group A and 3.00 times as much as that in group B. The activity and quantitation of the three groups were different significantly from each other (P < 0.01). CONCLUSION: The production of beta-lactamase in Pseudomonas aeruginosa biofilm bacteria is one of the main reasons of its resistance.

Anti-Bacterial Agents↗
PubMed2001

[The window parascapular free flap for the treatment of severe facial scar contracture].

OBJECTIVE: To present the clinical application of the window parascapular free flap. METHOD: The window parascapular free flap was used in 6 cases of serious facial burn scar contracture. The age of the patients ranged from 5 to 17 years. Based on circumflex scapular vessels, small windows were made on the flap for the palpebral fissure, the oral fissure, the nostrils or the external auditory meatus. The flap size ranged from 15 cm x 8 cm to 17 cm x 17 cm. All the free flaps were successful. RESULTS: With the survival of the free flap, the nose, the lids, the lips, etc. were reconstructed at the same time and obtained good appearance. CONCLUSION: For repair of serious facial burn scar contracture, the window parascapular free flap was successfully used to reconstruct the eye, the mouth, the nose and the ear. The method is safe and reliable because the blood supply of the scapular free flap was not affected by the opening.

Adolescent↗
PubMed2001

[Applied anatomic study of the pudendal-thigh flap and establishment of flap model].

OBJECTIVE: To investigate the anatomic base of the pudendal-thigh flap and establish flap model. METHODS: Skin dissection of pudendal-thigh regions was performed on 10 cadavers (20 sides). All afferent and efferent vessels were measured and recorded. RESULTS: There exist multiple blood supplies of pudendal-thigh flap. Anterior cutaneous branches of obturator artery spread out on middle portion of flap. Piercing site of it is (3.0 +/- 0.5) cm apart from middle line of perineum, (1.7 +/- 0.4) cm from anterior margin of vaginal introitus, (0.6 +/- 0.2) cm from outer fringe of lower pubic rami and (0.8 +/- 0.1) mm in diameter. Posterior labial arteries mainly supply the major labia and constantly anastomose with superficial external pudendal arteries in direct vascular anastomosis in subcutis of major labia. The main stems send out 2-3 lateral branches of posterior labial arteries which distribute to posterior portion of the pudendal-thigh flap. CONCLUSION: The major vessels of pudendal-thigh flaps used to form a neovagina are lateral branches of posterior labial arteries and not the main stem itself. Flaps pedicled on the anterior cutaneous branches of obturator arteries may be elevated to repair rectovaginal fistula or small skin defects of perineum and not suited to reconstruct a neovagina as its piercing point of blood vessels is much higher and the location of pedicle is more fixed.

Female↗
PubMed2001

Intracranial aneurysms: experience in treating 500 patients.

OBJECTIVE: To summarize the experience in surgical treatment of patients with intracranial aneurysms. METHODS: The measures used in the treatment of 500 patients with intracranial aneurysms were retrospectively reviewed with regard to timing of surgery, induced-hypotensive anesthesia, brain protection combined with temporal occlusion of the feeding artery, dynamically monitoring of transcranial Doppler ultrasound, antivasospasm treatment, techniques of direct surgery, and endovascular embolization. RESULTS: In 465 patients undergoing surgery, intraoperative rupture was observed in 27(6.2%), postoperative death in 13 (2.7%), hemipalsy in 8(2.2%), and vegetative state in 2 (5.0%). The operative mortality was 3.8% in 210 patients before 1990, while 1.9% in 255 patients after 1990. CONCLUSION: The outcome of patients with intracranial aneurysms can be markedly improved by comprehensive measures.

Adult↗
PubMed2001

[Penetrance of Leber hereditary optic neuropathy in Chinese individuals with mitochondrial DNA 11778 mutation].

OBJECTIVE: To analyze the penetrance of Leber hereditary optic neuropathy (LHON) in families with homoplasmic mitochondrial DNA (mtDNA) 11778 mutation. METHODS: Maternal relatives of 16 families were analyzed based on ocular phenotype and primary mtDNA mutation analysis. RESULTS: One hundred and thirty individuals from the 16 families harbored the 11778 mutation. Of the 130 individuals, 65 were male and 65 female. Forty-three individuals (34 male and 9 female) were affected with LHON. The penetrance of LHON in the 16 families ranged from 13.3% to 66.7%, with an average penetrance of 33.1%. Males, with an average penetrance of 52.3%, were more affected than females who had an average penetrance of 13.8%. About 79% of the affected individuals were male with a male to female ratio of 3.8: 1. The number of affected females found in the families analysis is greater than that in the probands analysis where only 3 of 41 probands with LHON and mtDNA11778 mutation were female(male to female ratio =12.7:1). CONCLUSION: The penetrance of LHON in Chinese individuals with homoplasmic mtDNA11778 mutation is about one third,which is within the range of that in Caucasion.

DNA Mutational Analysis↗
PubMed2001

Gene-CYP11B2 expression in rat liver in hepatic fibrogenesis induced by CCl4.

OBJECTIVE: To identify aldosterone synthase gene-CYP11B2 mRNA expression in normal and fibrotic liver in rats and evaluate the curative effect of antisterone. METHODS: 160 Wistar rats weighing about 250 g were divided into 4 groups. In the model group (n = 40), the rats were injected with 40% CCl4 (0.25 ml/100 g) subcutaneously three times a week. In the antisterone group (n = 40), the rats were injected with 40% CCl4 (0.25 ml/100 g) subcutaneously three times a week. Antisterone equivalent to 20 mg.kg-1.d-1 was given intragastrically (ig). In the malotilate group (n = 40), the rats were injected with 40% CCl4 (0.25 ml/100 g) subcutaneously three times a week. Malotilate equivalent to 50 mg/kg-1.d-1 was given ig. In the control group (n = 40), the rats were injected with olive oil only. After 2, 4, 6, 8 and 10 weeks, animals were sacrificed, and morphological examination was carried out. The area of collagen was examined with an Image Analyse System. Expression of the aldosterone synthase gene, CYP11B2 mRNA, in fibrotic and normal liver was detected by means of reverse transcriptase polymerase chain reaction (RT-PCR) and in situ hybridization. RESULTS: In situ hybridization and RT-PCR showed that the expression of CYP11B2 mRNA, which localized in the endoplasm of hepatic stellate cells (HSCs), was up regulated when fibrogenesis occurred. Histological observation indicated that the grade of fibrosis and the area of collagen in the antisterone group were less than those in model group before 6 weeks (P < 0.05). There was no significant difference between the antisterone and malotilate groups (P > 0.05). After that, however, the grade of fibrosis and the area of collagen in the antisterone group were higher than those in the malotilate group (P < 0.05). There was no significant difference between the antisterone and model groups (P > 0.05). CONCLUSIONS: The expression of CYP11B2 mRNA is up regulated in fibrotic liver. Antisterone can have a partial fibrogenesis-inhibiting effect in the early stages.

Animals↗
PubMed2001

Construction and primary characterization of Echinococcus multilocularis protoscolex cDNA expression library.

OBJECTIVE: To construct a lambda gt11 cDNA expression library of Echinococcus multilocularis protoscolex isolated in China. METHODS: Echinococcus multilocularis protoscolex mRNA was extracted using a Quickprep MicromRNA purification kit based on combining of the disruptive and protective properties of guanidinium thiocyanate (GTC) with the speed and selectivity of oligo (dT)-cellulose chromatography in a spum-column with some modification. Purified mRNA (1.8 micrograms) was submitted to reverse transcription using random hexamers [pd(N6)]. The double-strand blunt-ended cDNAs were ligated with an EcoRI/Notl adaptor to form a cohesive EcoRI end. Subsequently the synthesized cDNA was inserted into vector lambda gt11 EcoRI arms. After being packaged in vitro, lambda gt11 was put to an infectious bacteria Echinococcus coli (E. coli) strain Y1090; the recombinants were screened by color selection. PCR amplification was performed to evaluate the size of insertion DNA fragments. RESULTS: The recombinant ratio was nearly 100% and approximately 1 x 10(6) clones could be derived from this lambda gt11 cDNA library. PCR results indicated that the insertion DNAs were about 1.48 kb. CONCLUSIONS: A lambda gt11 cDNA expression library consisting of a million recombinant clones has been constructed from Echinococcus multicularis protoscolex mRNA. Further studies on this library are deserved.

Animals↗
PubMed2001

Management of hemangiopericytomas in the central nervous system.

OBJECTIVE: To elucidate the clinical features and treatment of Hemangiopericytomas (HPCs) in the central nervous system. METHODS: Twenty-six HPC operations performed at Huashan Hospital from January 1993 to June 1999 were analyzed retrospectively, and a review of relevant literatures was done. RESULTS: Among the 26 cases, total tumor removal was achieved in 24 cases, and subtotal removal in 2 cases. Postoperatively, neurological symptoms were improved or unchanged in 21 cases, worsened in 4 cases, and pneumonia caused death in 1 case. Eighteen patients received postoperative radiotherapy. Eighteen patients were followed up from 1 month to 58 months (average, 22 months). During the follow-up period, 2 patients presented one or more distant metastasis, and one patient died of recurrence. CONCLUSION: Surgical management is the best choice for treatment of patients with HPCs. Postoperative radiotherapy can postpone the risk of tumor recurrence.

Adolescent↗
PubMed2001

Regeneration of nNOS-containing nerve fibers in rat corpus cavernosum.

OBJECTIVE: To investigate the effect of cavernous nerve injury on the nNOS-containing nerve fibers in corpus cavernosum. METHODS: Thirty-three male Sprague Dawley (SD) rats were randomly divided into 3 groups: sham-operated controls (n = 5) underwent pelvic exploration without transection of the cavernous nerve; unilateral injury group (n = 14) had their cavernous nerve cut on one side; and bilateral injury group (n = 14) underwent neurotomy on both sides. Corpora cavernosa were harvested at the 3rd week and 6th month after surgery. nNOS-positive nerve fibers were examined with streptavidin-peroxidase immunohistochemistry techniques (SP method). RESULTS: After bilateral ablation, the nNOS-positive nerve fibers were significantly decreased at the 3rd week (17 +/- 4) and remained so at the 6th month (16 +/- 4). For the unilateral injury group, the nNOS-positive nerve fibers were similarly decreased on the side of the neurotomy at the 3rd week (18 +/- 6), but by the 6th month, the number increased significantly (61 +/- 9) and approximated the level on the contralateral side (81 +/- 13). CONCLUSION: Following unilateral cavernous nerve ablation in rats, nNOS-containing nerve fibers regenerate 6 months after surgery. This regeneration process does not occur in animals with bilateral cavernous nerve injury, suggesting that during radical pelvic surgery, the cavernous nerve has to be preserved at least on one side in order to maintain the capacity for penile erection.

Animals↗
PubMed2001

[Transrectal ultrasound examination of the prostate in 100 cases of prostate cancer].

OBJECTIVE: To evaluate the clinical value of transrectal ultrasound (TRUS) examination of the prostate in the diagnosis of prostate cancer (PCA). METHODS: The sonographic and clinical data of 100 patients with PCA were analyzed retrospectively. RESULTS: There was single lesion in 59 patients, diffuse lesion in 17 patients. The size of tumor in 35 patients was < or = 1.5 cm. TRUS in the diagnosis of PCA had an accuracy of 76.0%, specificity of 89.4%, false positive rate of 10.6% and negative predictive value of 88.9%. The level of prostate specific antigen (PSA) increased with the increase in the size of the tumor (P < 0.05). The PSA level of patients with poorly differentiated PCA was significantly higher than that in patients with well differentiated PCA. CONCLUSION: TRUS examination is a convenient procedure for the diagnosis of PCA in its early stage.

Aged↗
PubMed2001

[Biocompatibility of HA/TCP biphasic ceramics with co-cultured human osteoblasts in vitro].

The biocompatibility of HA/TCP ceramic was evaluated by investigation of attachment and growth of osteoblasts on biomaterial, as well as monitoring the effects of biomaterial on expression of functional phenotypes of co-cultured osteoblasts in vitro. When co-cultured with HA/TCP ceramics, osteoblasts firstly attached to the surface of HA/TCP disk, then attached to notches and grew into the micropores of biomaterial during further culture period. At last, the ceramics were almost packed with osteoblasts. Additionally, osteoblasts co-cultured with HA/TCP were similar to osteoblasts cultured under normal condition in osteoblastic phenotypes; the secreted lots of collagen type I, possess strong activity of Alkaline Phosphatase and mineralized extracellular matrix. The fact that osteoblasts could grow well on HA/TCP ceramics and the biomaterial did not affect their physiological function suggest that HA/TCP ceramic is biocompatible with human osteoblasts.

Biocompatible Materials↗
PubMed2001

[Preparation and analysis of pure type II collagen from porcine articular cartilage].

This investigation was aimed at the preparation of pure type II collagen from porcine articular cartilage and the feasible method for producing type II collagen in bulk. After dispersal of the porcine articular cartilage, the proteoglycans were extracted by guanidinium hydrochloride and dissolved by pepsin in acid solvent. The contaminants including denatured and degraded protein and other collagen was removed via the repeated procedure of purification. For obtaining the purer type II collagen, the chromatography with sepharose H. P. Column was also used. The purity of the sample was compared with the type II collagen produced by Sigma Company. Both type II collagens were characterized by SDS-PAGE electrophoresis, amino acid analysis and maximal violet chromatography, and all of the results accorded with the standard photograph in the references. The purity of the sample was higher than that of the product of Sigma Company. This prepared collagen of type II is a product of high purity. The raw materials are the common porcine articular cartilage, which is rich in resource and low in cost. Therefore, it is suitable to produce type II collagen in batches.

Amino Acids↗
PubMed2001

Expression of hHR21sp gene by peripheral blood and hematopoietic cells of normal subjects and Fanconi anemia patients.

OBJECTIVE: The radiation sensitive gene rad 21 of Schizosaccharomyces pombe is involved in the repair of double-stranded breaks in DNA and is essential for mitotic growth. The hHR21sp gene is its human homologue. In an attempt to investigate the role of hHR21sp in DNA repair, we studied the effects of UV and gamma-ray irradiation on hHR21sp gene expression in normal human peripheral blood cells, and non-iradiated peripheral and bone marrow cells from Fanconi anemia (FA) patients who have shown DNA repair deficiency. METHODS: Total steady state RNA was extracted from peripheral blood cells and bone marrow. RNA transcripts were quantified after RT-PCR and Southern blot, phosphoimmage and autoradiogram analysis. The results were compared with control groups. RESULTS: hHR21sp expression was significantly increased from 3 h to 9 h after UV irradiation in peripheral blood cells from normal subjects at doses of 40-80 j/m2 (P < 0.05). hHR21sp was also up-regulated by gamma-ray irradiation at 6 h to 9 h at dose of 1 to 5 Gy (P < 0.01), which was more significant than the UV irradiation. In the non-irradiated FA patient group, hHR21sp expression was decreased in bone marrow hematopoietic cells (P < 0.05). After activation by PHA and IL-2, there was still a significant depression in expression by the FA patients peripheral blood cells compared with control groups (P < 0.05). CONCLUSION: hHR21sp was up-regulated at doses and times irradiated at the range tested in normal peripheral blood cells, and is more affected by gamma-ray irradiation than UV irradiation. FA patient bone marrow hematopoietic cells and peripheral blood mononuclear cells showed down-regulation of hHR21sp expression. The results imply that defects in DNA repair via hHR21sp expression may play an important role in the pathogenesis of FA syndrome.

Adolescent↗