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Biomedical subjects

N Li

Publications and source records attributed to N Li.

At least 289 records · Page 16Linked to original sources
PubMed1998

[Study on the preventive effect of tea on DNA damage of the buccal mucosa cells in oral leukoplakias induce by cigarette smoking].

In order to study the preventive effect of tea on DNA damage induced by cigarette smoking and to provide further evidence on the protective effects of tea in human cancer, a 6-month, double-blind and randomized placebo-controlled intervention trial was carried out. The effect of tea on micronuclei frequency in exfoliated oral buccal mucosa cells in 36 oral leukoplakias of smokers was investigated. A kind of mixed tea given in an oral dose of 3 g/day and a concentration of 0.1% smeared on mucosa lession three times a day for 3 months and 6 months, significantly decreased the micronuclei formation in exfoliated oral buccal mucosa cells in subjects with oral leukoplakias. In contrast, there was no change in the micronuclei frequency after 6 months in the placebo group. The results indicate that mixed tea may reduce the oral cancer risk by preventing DNA damage in oral leukopiakias induced by cigarette smoking.

Adult↗
PubMed1998

[A clinical and pathological study of cerebellar medulloblastoma in adult patients].

OBJECTIVE: In order to study the clinicopathological characteristics, histogenesis and prognosis of medulloblastoma in the adult patients. METHODS: Altogether 27 patients of medulloblastoma admitted form 1974-1995 were reviewed. RESULTS: In all of the cases, age ranged from 16 to 55, (average 25.8 years) with 21 tumors localized in the cerebellar vermis, and 6 tumors in the cerebellum. Among them, 12 cases were completely while 14 cases were subtotally removed and biopsy was done in only one case. In the 21 patients to be followed up, 7 survived for 2.5-17 years after the operation, and 14 died. The average survival period was 41.6 months. One year survival rate was 71.4%, five years and ten years survival rates were 14.3% respectively. Regarding to the histological types, 14 cases were considered to be classic and 13 cases were desmoplastic by histological classification. CONCLUSION: Medulloblastoma keeps still the ability of differentiation to neurons and astrocytes confirmed by electronmicroscopy and immunohistochemical staining for Syn, NSE and GFAP. Factors considered responsible to the prognosis included age, tumor location, various therapeutic measurements and the histological classification.

Adolescent↗
PubMed1998

[The effect of tissue inhibitor of metalloproteinase-2 gene (TIMP-2 gene) on gastric carcinoma cells in vitro and in vivo].

OBJECTIVE: To study the effect of TIMP-2 gene on the invasive behavior of gastric carcinoma cells and to explore the possibility of blocking tumor metastasis. METHODS: TIMP-2 gene was transferred into human gastric cancer cell line SGC-7901 by lipofection technology. The ability of tumor cell invasion was detected by Boyden chamber in vitro and tumor invasion animal model in vivo. Type IV collagen and type IV collagenase were detected by immunohistochemical technique. RESULTS: The invasive ability of gastric cancer cells SGC-7901 transfected with TIMP-2 gene was significantly inhibited in vivo and in vitro. The expression of type IV collagenase in the untransfected group was higher than in the transfected group. CONCLUSIONS: TIMP-2 gene transfection can reduce the ability of gastric cancer cell invasion in vitro and in vivo.

Adenocarcinoma↗
PubMed1998

[Radioimmunoimaging of bladder tumor with the intravesical administration of technetium -99m labelled monoclonal antibody].

OBJECTIVE: To make radioimmunoimaging of bladder tumor simple, safe and reliable. METHODS: Anti-human bladder carcinoma cell line BIU-87 monoclonal antibody-BDI-1 was labelled with technetium -99m by direct mercaptoethanol reducing method. RESULTS: The labelling rate was 69.6% and the radiochemistry pruity was higher than 95%. 33 patients received radioimmunoimaging of bladder tumor with the intravesical administration of technetium -99m labelled monoclonal antibody. The false positive rate was zero. 88.5% of all 29 bladder cancer patients had got positive immunoscintigraphy results, and 65.2% of them were confirmed by cystoscopic results. Both primary and recurrent tumor could be detected clearly and the smallest tumor detected was 0.5 cm in diameter. There were some differences between the radioimmunoimaging and cystoscopic results in 7 of 11 multitumor cases, which included tumor size, number and location. CONCLUSION: It is required to use more suitable isotopes and/or monoclonal antibodies to increase its sensitivity.

Administration, Intravesical↗
PubMed1998

[Studies on Epstein-Barr virus in patients with primary sinonasal non-Hodgkin's lymphoma].

OBJECTIVE: To study the relationship between Epstein-Barr virus (EBV) infection and primary sinonasal non-Hodgkin's lymphoma. METHODS: Using polymerase chain reaction (PCR) method, 22 patients with primary sinonasal non-Hodgkin's lymphoma (NHL), including 13 tumours of T cell type and 9 of B cell type, and mucosa from twenty cases of nasonasosinusitis were tested for the presence of Epstein-Barr virus (EBV) DNA. RESULTS: The results showed that 14 of 22 non-Hodgkin's lymphoma (63.6%) and 4 of 20 nasonasosinusitis mucosa (20%) were EBV-DNAase gene positive (9 T cell type and 5 B cell type). The difference between non-Hodgkin's lymphoma and nasal mucosa was statistically significant (P < 0.005). CONCLUSION: These results suggest that EBV is not only present in B lymphocyte lymphomas but also in T lymphocyte lymphomas.

Adolescent↗
PubMed1998

[The use of nasopharyngeal fiberoscope and obturator for treating velopharngeal incompetence].

OBJECTIVE: Using NPF and obturator to treat velopharyngeal incompetence. METHODS: Obturator was made based on the size of the velopharyngeal aperture determined with NPF. RESULTS: All of 45 cases was better in the velopharyngeal function, 15 cases (33%) had normal speech when the obturator was taken away after 2 years. CONCLUSION: This is a good conservative method for treating VPI of cleft palate postsurgery.

Adolescent↗
PubMed1998

[The reconstruction of mandible and soft tissue defects with the osteocutaneous free fibula flap].

OBJECTIVE: To find a new material to reconstruct the defects involving mandible and the surrounding soft tissues with the donor site morbidity mild and transient. METHODS: Ten consecutive fibula free flaps were used to reconstruct composite defect of mandible and soft tissue. The average length of the fibular graft was 9.1 cm, and the average size of the cutaneous-flap was 4.5 cm x 6.2 cm. RESULTS: 99mTcO4- scan demonstrated that 9 flaps were survivial (9/10) 2 weeks postsurgery. The function and the contour of the mandible were excellent. The donor site morbidity was mild and transient. CONCLUSION: Fibula has a high density of cortical bone. There is enough bone available to reconstruct mandible defect. The osteocutaneous fibula flap is a new material to reconstruct the composite mandible and soft tissue defects.

Adult↗
PubMed1998

[The experimental research of free calcium of the lens epithelial cells in galactose cataract].

OBJECTIVE: To study the changes of free calcium in the lens epithelial cells (LECs) of galactose cataract. METHODS: Wistar rats, 28 days old, were fed with 50% galactose forage to form cataract models. Then the concentration of free calcium of LECs was measured at the 1st, 3rd, 7th, 10th, 14th, 19th days after the galactose diet was given. RESULT: The concentrations of free calcium in LECs of galactose cataract increased apparently and reached the maximum at the 10th day after galactose diet. The maximum was 4 - 5 times higher than that of the normal group. CONCLUSION: The calcium concentration of LECs in galactose cataract increases but the degrees at different phases are not the same. The maximal concentration is at the phase when the cortex is opacified.

Animals↗
PubMed1998

[Problems and solutions in the use of RAPD to the identification of the Chinese drugs "xi-xin" (Herba asari) and its substitutes].

The use of random amplified polymorphic DNAs (RAPD) on the identification of crude drugs has a few special problems, e.g., the influence of the degree of degradation of DNA templates on the amplified products, the reliability of results by one or two primers and the application range of RAPD, etc., so the problems were discussed through researches on Herba Asari. In this experiment, the DNA of twenty-one samples from different locations and collected at different time were extracted. The suitable concentrations of DNA templates and the suitable primers were selected. After this, the DNA of these samples were amplified by RAPD. The results showed that the concentration and the degree of degradation of DNA templates, and the different sources of crude drugs affected the result of RAPD assay. Some suggestions were made to solve these problems, such as the selection of DNA templates concentration, the screening of suitable primers, and the use of contrast groups and cluster analysis. Furthermore, the application range of RAPD to the identification of crude drugs was discussed. All of these will provide the guide to the use of RAPD for the identification of crude drugs.

Asarum↗
PubMed1998

[Monitoring calcium in outer hair cells with confocal microscopy and fluorescence ratios of fluo-3 and fura-red].

Calcium distribution and mobilization during mechanical stimulation in outer hair cells of the guinea pig were monitored using laser scanning confocal microscopy and co-loaded fluo-3 and fura-red fluorescent probes. Spatial calcium gradients were revealed among various subcellular areas. The ratios of the fluorescence intensity of fluo-3 and fura-red were 1.71 +/- 0.85, 1.61 +/- 0.75, 1.47 +/- 0.65 and 1.39 +/- 0.66 for the cytoplasm, the cytoplasmic membrane, the cuticular plate and the nucleus respectively, indicating that free calcium ion concentrations are the highest in the cytoplasm and the lowest in the nucleus. While the calcium concentration remained relatively constant under resting conditions, it increased during mechanical stimulation. The results show that confocal ratio imaging of fluo-3 and fura-red enables us to determine more accurately the subcellular calcium distribution and that the calcium ions make a contribution to the mechanic-electrical transduction in hair cells.

Aniline Compounds↗
PubMed1998

[Effects of biomaterials on immunoglobulins and biochemistry in serum of extracoporal circulation].

The polyvinyl chloride(PVC) tube coated with cellulose acetate(CA), polyether suffone(PES), polyurethane(PU), silicon rubber(SR) and polyester fibre(PETF) were put in contact with circular serum at 37 degrees C. According to different time-periods of exposure, the immunoglobulins (G.A.M), albumin(ALB), total protein (TP) and total cholesteral(Tch) in serum were measured by an IL-Monarch biomedical analyser. The results showed that the levels of immunoglobutins significantly decreased after the serum came in contact with CA, PETF, SR and that the levels of ALB, TP and Tch were significantly lower in the serum exposed to PETF while those in the serum exposed to other materials were normal. These changes may relate to the complement activation induced by different materials.

Biocompatible Materials↗
PubMed1998

Gene array and expression of mouse retina guanylate cyclase activating proteins 1 and 2.

PURPOSE: To identify gene arrangement, chromosomal localization, and expression pattern of mouse guanylate cyclase activating proteins GCAP1 and GCAP2, retina-specific Ca2+-binding proteins, and photoreceptor guanylate cyclase activators. METHODS: The GCAP1 and GCAP2 genes were cloned from genomic libraries and sequenced. The chromosomal localization of the GCAP array was determined using fluorescent in situ hybridization. The expression of GCAP1 and GCAP2 in mouse retinal tissue was determined by immunocytochemistry. RESULTS: In this study, the mouse GCAP1 and GCAP2 gene array, its chromosomal localization, RNA transcripts, and immunolocalization of the gene products were fully characterized. The GCAP tail-to-tail array is located at the D band of chromosome 17. Each gene is transcribed into a single transcript of 0.8 kb (GCAP1) and 2 kb (GCAP2). Immunocytochemistry showed that both GCAP genes are expressed in retinal photoreceptor cells, but GCAP2 was nearly undetectable in cones. GCAP2 was also found in amacrine and ganglion cells of the inner retina. Light-adapted and dark-adapted retinas showed no significant difference in the distribution of the most intense GCAP2 staining within the outer segment and outer plexiform layers. CONCLUSIONS: Identical GCAP gene structures and the existence of the tail-to-tail gene array in mouse and human suggest an ancient gene duplication-inversion event preceding mammalian diversification. Identification of both GCAPs in synaptic regions, and of GCAP2 in the inner retina suggest roles of these Ca-binding proteins in addition to regulation of phototransduction.

Adaptation, Ocular↗
PubMed1997

The safety and pharmacokinetics of single-agent and combination therapy with megestrol acetate and dronabinol for the treatment of HIV wasting syndrome. The DATRI 004 Study Group. Division of AIDS Treatment Research Initiative.

This randomized, open-labeled, multicenter study was designed to assess safety and pharmacokinetics of dronabinol (Marinol) tablets and megestrol acetate (Megace) micronized tablets, alone and in combination, for treatment of HIV wasting syndrome. Weight and quality of life data were also collected. Fifty-two patients (mean CD4+ count, 59 cells/microliter) were randomized to one of four treatment arms: dronabinol 2.5 mg twice/day (D); megestrol acetate 750 mg/day (M750); megestrol acetate 750 mg/day+dronabinol 2.5 mg twice/day (M750+D); or megestrol acetate 250 mg/day+dronabinol 2.5 mg twice/day (M250+D). After therapy initiation, 47 patients returned for at least one visit, and 39 completed the planned 12 weeks of study visits. Occurrence of adverse events, drug discontinuation, new AIDS-defining conditions, or CD4+ T lymphocyte changes were not statistically significantly different among arms. Serious adverse events assessed as related to dronabinol included CNS events (e.g., confusion, anxiety, emotional lability, euphoria, hallucinations) and those assessed as related to megestrol acetate included dyspnea, liver enzyme changes, and hyperglycemia. The mean weight change +/- SE over 12 weeks was as follows: D, -2.0 +/- 1.3 kg; M750, +6.5 +/- 1.1 kg; M750+D, +6.0 +/- 1.0 kg; and M250+D, -0.3 +/- 1.0 kg (difference among treatment arms, p = 0.0001). Pharmacokinetic parameters measured after 2 weeks of therapy for M750 were Cmax = 985 ng/ml and AUC = 22,487 ng x hr/ml, and for dronabinol and its active metabolite (HO-THC), respectively, were Cmax = 2.01; 4.61 ng/ml and AUC = 5.3; 23.7 ng x hr/ml. For megestrol acetate, but not dronabinol, there was a positive correlation at week 2 between both Cmax and AUC with each of the following: (1) weight change, (2) breakfast visual analog scale for hunger (VASH) score, and (3) dinner VASH score.

Adolescent↗
PubMed1997

Structure-activity studies of the inhibition of serine beta-lactamases by phosphonate monoesters.

A new series of phosphonyl derivatives has been prepared and tested for inhibition of serine (class A and C) beta-lactamases. Variations of the leaving group in a series of methyl phosphonates showed that leaving groups better than the previously employed p-nitrophenoxide could give more effective inhibitors. Inclusion of a negative charge in the leaving group did not, per se, lead to better inhibitors. Aryl phosphonates appeared more effective than those with electronically comparable but smaller leaving groups. The combination of a good leaving group, 2,4-dinitrophenoxide, with an amido side-chain, phenylmethylsulfonamido--the latter rather than phenylacetamido in order to increase the stability of the compound with respect to intramolecular nucleophilic catalysis of hydrolysis by the amide group--did not yield overall a better inhibitor than previously employed p-nitrophenyl phosphonates. These results give the first indication of specific interactions between a beta-lactamase and the leaving group of a phosphonate inhibitor. Only one enantiomer of a chiral thiophosphonate, presumably the Rp isomer, was an effective inhibitor. Addition of either a D- or a L-methyl group to the methylene group of a p-nitrophenyl amidomethylphosphonate did not enhance the inhibitory ability of the phosphonate. Class A beta-lactamases remain refractory to phosphonates.

Esters↗
PubMed1997

Biodistribution of model 105Rh-labeled tetradentate thiamacrocycles in rats.

105Rh(III)Cl2 complexes with a limited series of [14]ane- and [16]ane- thia macrocycles were prepared and their biodistributions in Sprague-Dawley rats studied. These studies demonstrate that modifications in the structure and composition of the 105Rh-thia macrocycle complexes produce significant differences in their uptake and retention in both the liver and kidneys. The results indicate that the cis-Rh(III)Cl2-[14]ane thiamacrocycles exhibit less kidney retention than the corresponding trans-Rh(III)Cl2-[16]ane thiamacrocycles. In addition, the presence of a side chain containing a carboxylate group will produce decreased retention of activity in the kidneys. HPLC analysis of urine from these animals indicates no observable in vivo metabolism or dissociation of these chelates in the blood stream.

Animals↗
PubMed1997

In vitro and in vivo characterization of novel water-soluble dithio-bisphosphine 99mTc complexes.

The water-soluble dithio-bis(hydroxymethyl)phosphine ligands (HOH2C)2P(CH2)2 S(CH2)3S(CH2)2P(CH2OH)2 and (HOH2C)2P(CH2)3S(CH2)3S(CH2)3P(CH2OH)2 were complexed with 99mTc. The 99mTc-P2S2 complexes were formed in high radiochemical purity by simple mixing of 99mTcO-4 with the ligands or by transchelation from 99mTc-citrate. The 99mTc-P2S2 complexes were stable over a wide range of pHs and did not undergo in vitro decomposition for < or = 24 h. High performance liquid chromatographic analysis indicated the formation of singular chemical species. Retention times for each of the new 99mTc-P2S2 complexes are identical to those of corresponding Re(V) complexes, suggesting similar chemical species at the tracer level. Results of this study suggest that the combination of thioether and (hydroxymethyl)phosphine donor centers in new, multidentate ligand frameworks might aid in the development of new bifunctional chelating agents for the use of radiolabeling specific biomolecules.

Animals↗
PubMed1997

A sensitive flow cytometric assay for circulating platelet-leucocyte aggregates.

A whole blood flow cytometric method for studies of platelet-leucocyte aggregates (PLAs) in vivo, involving neither fixation nor centrifugation, is described. With this method, PLAs in the total leucocyte population (PLA/L) were 15.3 +/- 8.5% in 36 healthy volunteers. Blocking antibodies had little effect on PLAs in the absence of in vitro stimulation, suggesting that the aggregates were preformed in vivo. Fixation with formaldehyde or paraformaldehyde increased PLA/L significantly. Similarly, prefixation of the blood or red blood cell lysis, with repeated washing and centrifugation, caused artefactual 3-5-fold increases in PLAs (P<0.05). ADP, thrombin, platelet activating factor (PAF) or N-formyl-methionyl-leucyl-phenylalanine (fMLP) each increased PLA formation in unfixed whole blood dose-dependently: additive effects were found when they were combined. Experiments with blocking MAbs suggested that different ligand-receptor systems mediate PLA formation by different agonists. PLA formation by the platelet agonist ADP was inhibited by P-selectin blockade, but enhanced by GPIIb/IIIa blockade (which inhibits platelet-platelet interactions). PLA formation by the leucocyte agonist fMLP was inhibited by GPIIb/IIIa blockade, suggesting linking via fibrinogen. Platelet-leucocyte aggregate analysis by this whole blood method appears to reflect in vivo conditions, and enables investigations of the mechanisms involved in their formation.

Adenosine Diphosphate↗