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Biomedical subjects

R Li

Publications and source records attributed to R Li.

At least 253 records · Page 14Linked to original sources
PubMed1999

Antipeptide antibodies reveal interrelationships of MBP 200 and MBP 235: unique apoB-specific receptors for triglyceride-rich lipoproteins on human monocyte-macrophages.

Two human monocyte-macrophage (HMM) membrane binding proteins, (MBP) 200 and 235, are receptor candidates that bind to the apolipoprotein (apo)B-48 domain in triglyceride-rich lipoproteins for uptake independent of apoE. Microsequence analysis of the purified reduced MBP 200R characterized tryptic peptides of MBP 200R. A synthetic peptide mimicking a unique, unambiguous 10-residue sequence (AEGLMVTGGR) induced antipeptide antibodies that specifically recognized MBP 200, 235 and 200R, in 1- and 2-dimensional analyses, indicating 1) the ligand binding protein was sequenced and 2) MBP 200 and 235 yielded MBP 200R upon reduction. These antibodies identified the MBPs in human blood-borne, THP-1, U937 MMs, and endothelial cells (EC) but not in human fibroblasts or Chinese hamster ovary (CHO) cells. Fluorescence activated cell sorting (FACS) analysis located the MBPs on the MM surface as necessary for receptor function. The 10-residue, unambiguous MBP 200-derived sequence is unique, with no matches in extant protein databases. Antipeptide antibodies bind to the MBPs in reticuloendothelial cells that have this receptor activity, but not to proteins in cells that lack this receptor activity. These studies provide the first direct protein sequence and immunochemical data that a new, unique apoB receptor for triglyceride-rich lipoproteins exists in human monocytes, macrophages, and endothelial cells.

Amino Acid Sequence↗
PubMed1999

l-S.R-daurisoline protects cultured hippocampal neurons against glutamate neurotoxicity by reducing nitric oxide production.

AIM: To explore mechanisms of l-S.R-daurisoline (DS)-mediated protection of cultured hippocampal neurons from sodium glutamate (Glu) cytotoxicity. METHODS: Cultured neurons obtained from rat hippocampus were used to examine the protective effect of DS against Glu neurotoxicity. Cell viability was estimated using trypan blue dye exclusion method and [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay. Release of nitric oxide (NO) from the hippocampus was assayed using rat thoracic aorta in vitro. RESULTS: DS 0.01-10 mumol.L-1 concentration-dependently inhibited Glu cytotoxicity and increased cell viability with 50% prevention of cell death 2.8 mumol.L-1 (95% confidence limit 1.2-5.9 mumol.L-1). This protection was mostly attenuated by L-arginine (Arg) 1 mmol.L-1. DS 0.01-10 mumol.L-1 did not prevent sodium nitropusside (SNP) 500 mumol.L-1-induced cytotoxicity. DS 10 mumol.L-1 blocked Glu-elicited relaxation of the endothelium-denued rat aortic rings contracted by norepinephrine (NE) 10 mumol.L-1 in the presence of hippocampal tissue, but did not affect that induced by SNP. This indicated that DS inhibited Glu-triggered NO generation but did not prevent the effects of NO. CONCLUSION: DS prevented neurons from Glu neurotoxicity by inhibiting Glu-triggered NO generation.

Alkaloids↗
PubMed1999

Nimodipine inhibits calcium-independent nitric oxide synthase activity in transient focal cerebral ischemia rats and cultured mouse astroglial cells.

The effect of nimodipine on nitric oxide synthase (NOS) activities in brains in transient focal cerebral ischemia rats, in cultured mouse neurons and astroglial cells and bovine brain capillary endothelial cells (BCECs) was investigated. The administration of nimodipine (3 mg.kg(-1), p.o., twice a day, for 3 days) before middle cerebral artery (MCA) occlusion significantly reduced infarct size, decreased nitrite/nitrate (NOx) content and inhibited Ca2+-independent NOS activity in the infarct area. Nimodipine inhibited the Ca2+-independent NOS activity induced by lipopolysaccharide (LPS) + tumor necrosis factor alpha (TNF alpha) in mouse astroglial cells with an IC50 value of 0.036+/-0.003 mM and Ca2+-dependent NOS activity in mouse neurons with an IC50 value of 0.047+/-0.003 mM, but did not affect Ca2+-dependent NOS activity in BCECs. The inhibition of Ca2+-independent NOS activity by nimodipine in astroglial cells was competitive with respect to L-arginine. Nimodipine also inhibited the induction of Ca2+-independent NOS activity in vitro. These results suggest that nimodipine in addition to its cerebral vasodilating effect may protect brain from ischemic neuronal damage through modifying NOS activity.

Animals↗
PubMed1999

[The epidemiological study on limb deformities among children in Guangdong Province].

OBJECTIVE: To study the incidence of limb deformities of children in Guangdong province. METHODS: Physical examination on lined-up students and looked over one by one. Detailed examinations of orthopaedics or related subjects were performed on those with susceptive deformity. RESULTS: Results showed that there were 655 cases of limb deformities (0.64%) in 102,313 pupils of 7 to 14 years old, in which 550 cases (83.97%) needed surgical intervention. The incidence of deformity in economically poor areas was 2.88 times higher than those in advanced areas. CONCLUSION: Prevention and cure of limb deformities of children, especially those in rural area, should be addressed and emphasized.

Adolescent↗
PubMed1999

Transgenic potato plants expressing osmotin gene inhibits fungal development in inoculated leaves.

Osmotin, a 24-KD protein isolated from Nicotiana tabacum 'Xanthi nc' was very toxic to Phytophthora infestans in vitro assay. Transgenic potato plants expressing wild osmotin protein delayed the emergence of symptoms of disease. Two osmotin mutants have been produced by PCR mutagenesis. One mutant, delta C18 osmotin, had a nonsense mutation near the C-terminus that deleted the carboxyl terminal prepropeptide (CTPP) of 18 amino acids. Another mutant, osmotin-P, had amber mutation at 96th amino acid. Both mutant genes driven by CaMV d35S promoter were introduced in potato by Agrobacterium mediated genetic transformation. The expression and osmotin protein accumulation in transgenic potato were detected by Southern, Northern, and Dot-blot ELISA assay. Disease resistance test using P.infestens complex race showed that expression of both osmotin mutants in transgenic potato reduced the lesion growth rate in inoculated leaves. The results showed that accumulation of osmotin protein in intercellular spaces (delta C18osmotin) inhibited the development of fungal disease in inoculated leaves. Based on the results we suggest that antifungal activity was possibly located at N end of osmotin protein (osmotin-P).

Blotting, Northern↗
PubMed1999

[The evaluation of 156 cycles of intracytoplasmic sperm injection in the management of male infertility and idiopathic infertility].

OBJECTIVE: The aim of this study was to examine, retrospectively, the efficacy of intracytoplasmic sperm injection (ICSI) in the treatment of male infertility and idiopathic infertility. METHODS: From November 1995 to January 1998, 140 couples (156 cycles) received ICSI because of severe male factor infertility or idiopathic infertility in our assisted reproductive technology center. The treatment cycles were divided into two groups, group I included 74 cycles done before May 1997, group II included 82 cycles done after May 1997. Mature oocytes were selected for microinjection. RESULTS: No differences were observed between the two groups in the number of mature oocyte and the total cleavage rate. Oocyte survival rate, normal fertilization rate, embryos of good morphology rate and clinical pregnancy rate were significantly higher in group II than that in group I. CONCLUSION: ICSI procedure does affect the quality of embryos. With the improvement of ICSI technique, ICSI should be the treatment of choice for male infertility and idiopathic infertility.

Adult↗
PubMed1999

[Gonadotropin releasing hormone agonists in the treatment of adenomyosis with infertility].

OBJECTIVE: To Study the role of gonadotropin releasing hormone agonists (GnRH-alpha) in the treatment of adenomyosis with infertility. METHODS: Adenomyosis was diagnosed under lapososcopy in 4 infertile cases. Meanwhile coexsting endometriosis, pelvic adhesion and adenomyoma were treated by surgery and endocoagulator in 4 and 2 cases respectively. GnRH-alpha (triptorelin or goserelin) therapy was given for six months before laparoscopic surgery in 1 case and after laparoscopic surgery in 3 cases. Their fecundity outcome were followed-up after cessation of GnRH-alpha treatment. RESULTS: All cases became amenorrheic during GnRH-alpha therapy. The enlarged uteri all decreased to normal or near normal size. Menstruation returned in 80-90 days after cessation of treatment. Three cases conceived within four menstrual periods. One of them resulted in the birth of a healthy 3 150 g male at 38 weeks gestation by cesarean section. The second pregnancy resulting after adenomyomectomy was terminated by emergent cesarean section at 30 weeks gestation because of threatened rupture of uterus. The third is now normal at 28 weeks pregnancy. The fourth has had 2 menstrual periods and is still being followed up. CONCLUSION: (1) GnRH-alpha thus used is efficient in reducing the adenomyotic uterine size, and may facilitate fertility. (2) For ademyomata associated with infertility, GnRH-alpha therapy may avoid the risk of rupture of uterus which may occur after adenomyomectomy pregnancy. (3) For infertility, GnRH-alpha treatment before laparoscopic surgery greatly decreases surgical difficulties and blood loss in certain cases.

Adult↗
PubMed1999

[Study on decidual and villous cells apoptosis and its control gene in medical abortion].

OBJECTIVE: To study relationship of decidual and villous cells apoptosis and its control gene B-cell lymphoma/leukemia-2(bcl-2), bcl-2 associated X protein (bax) with medical abortion. METHODS: Forty four women who volunteered to terminate their pregnancy were divided into 3 group: mifepristone group (exp. 1, n = 15), mifepristone with misoprostol group (exp. II, n = 14) and control group (n = 15). The cell cycles of DNA of the decidual and villous cells stained with Propidium Iodide (PI) were analyzed and bcl-2 and bax gene protein labeled with immuno-fluorescence were detected by flow cytometry. RESULTS: The percentage of decidual cells apoptosis were (14.0 +/- 3.9)%, (22.9 +/- 6.3)%, (5.3 +/- 9.3)% and of villous apoptosis were (10.9 +/- 2.8)%, (13.9 +/- 4.7)%, (4.6 +/- 3.0)% in exp. I, exp. II and control group respectively. The apoptotic percentages in decidual and villous cells of exp. I and exp. II groups were significantly higher than that of control (P < 0.01-0.001). On DNA histogram, apoptosis peaks appeared in all the groups. The decidual cell apoptosis of exp. II groups was significantly higher than that of exp. I group (P < 0.01). Both decidual apoptotic percentages of exp. I and exp. II groups were significantly higher than that of villous (P < 0.01). Decidual bcl-2/bax ratio were 1.4 +/- 0.7, 0.9 +/- 0.3, 1.4 +/- 0.7 and villous bcl-2/bax ratio were 1.0 +/- 0.4, 0.8 +/- 0.3, 1.4 +/- 0.6 in the 3 groups respectively. Both decidual and villous bcl-2/bax ratio of exp. II group was significantly lower than that of control (P < 0.05-0.01) which was in consistent with apoptosis. CONCLUSIONS: These data indicated that mifepristone with misocprostol for terminating human early pregnancy might be realized by inducing decidual and villous cells excessive apoptosis. The descent of bcl-2/bax ratio could be one of the factors of inducing decidual and villous apoptosis.

Abortifacient Agents, Nonsteroidal↗
PubMed1999

[Expression of focal adhesion kinase in lymphatic endothelial cells of metastasis].

This study was directed at the expression of focal adhesion kinase (pp125FAK) which is located together with vinculin and talin in the spot of cellular adhesion. The authors' intention was to collect reliable data on this important kinase in the signal pathways so as to provide in-depth materials for exploring the mechanism of tumor metastasis to lymphatic vessels. The immunohistochemical method was used to study the expression of FAK in lymphatic endothelial cells of metastaltci adenocarcinoma of rectum and its adjacent lymph-nodes. The result demonstrated that lymphatic endothelial cells expressed pp125FAK when lymphatic vessels were invaded by cancer cells. Reaction production was located in the cytoplasm. This study provides that there was a strong correlation between the expression of FAK in lymphatic endothelial cells and the metastasis of cancer to lymphatic vessels.

Adenocarcinoma↗
PubMed1999

[Apoptosis and necrosis of neuron after focal ischemia in brain of rats].

This article reports the apoptosis and necrosis of neurons following ischemia-reperfusion in the brain of rats. The focal ischemia model was established by occluding the middle cerebral artery for 2 h and reperfusing for 0.5-48 h. The neuronal changes were investigated by HE staining, TUNEL and agarose gel-electrophoresis. The foci of ischemia were in the preoptic area, striatum and cortex. At 0.5 h of reperfusion, there were quite a few apoptotic neurons in the preoptic ischemic focus, but only a few scattered apoptotic cells were seen in the striatum and cortex. During 3-6 h of reperfusion, the number of apoptotic cells increased and the necrotic cells appeared. The number of apoptotic cells reached a peak at 12-24 h and the in morphology varied, and they were mainly located in the inner boundary of infarct. At 48 h, the apoptotic cells decreased; and the necrotic cells increased. Agarose gel-electrophoresis showed the dense smear and ladder pattern of DNA fragments, the apoptosis and necrosis of neurons coexisted, and apoptosis contributed to the enlargement of the ischemic infarct.

Animals↗
PubMed1999

[Expression of transferrin receptor and ferrochelatase mRNAs in MEL cells].

OBJECTIVE: To investigate the changes of transferrin receptor (TfR) mRNA and ferrochelatase mRNA levels under different iron status of DMSO induced or non-induced MEL cells. METHODS: MEL cells were induced with 1.5% DMSO. TfR mRNA and ferrochelatase mRNA were assayed by Northern blot after adding transferrin, deferrioxamine, anti-TfR monoclonal antibody (McAb) or Epo, respectively. RESULTS AND CONCLUSION: 1. TfR mRNA level increased with cell proliferation in non-induced MEL cells, while in the induced MEL cells, although the proliferating capacity was losing with cell maturation, TfR mRNA level increased with hemoglobin synthesis and its amplitude was higher than that in non-induced cells. 2. In both non-induced and induced MEL cells, TfR mRNA levels increased when intracellular iron level decreased; and vice versa. 3. Stimulation of erythropoiesis by Epo increased the expression of TfR mRNA, indicating that its expression in erythroid cells was regulated by the level of intracellular iron and the synthesis of heme. 4. The expression of ferrochelatase mRNA had no change in non-induced MEL cells, but increased significantly in induced MEL cells. 5. The level of intracellular iron in non-induced and induced MEL cells had less effects on the expression of ferrochelatase mRNA.

Animals↗
PubMed1999

[Reconstruction of perforating defects of the maxillofacial region with double flaps].

OBJECTIVE: To solve the problems in restoration of perforating (full thickness) defects in the maxillofacial region. METHODS: Double flaps have been used to reconstruct the defects. Forty-five patients with full thickness defects on the maxillofacial region were treated with 90 flaps, including 58 (64%) deltopectoral flaps, the platysma myocutaneous flap, pectoralis major myocutaneous flap, sternomastoid myocutaneous flap, forehead flap and latissimus myocutaneous flap. RESULTS: The operation results were satisfactory. Of the 90 flaps, 87 flaps survived completely or subtotally with a successful rate of 97%. Three flaps sustained total or large necrosis. CONCLUSION: A number of flaps can be used for repairing the full thickness defects of the maxillofacial region, especially the deltopectoral flap, the platysma myocutaneous flap and the pectoralis major myocutaneous flap. They can provide excellent external cover or internal lining. They are well vascularized, hairless and colour-matched.

Adolescent↗
PubMed1999

Resistant mechanisms of Candida albicans to fluconazole.

OBJECTIVE: To detect the resistant mechanisms of Candida albicans to fluconazole (FCZ) at molecular biology level, since the resistance mechanisms of azole antifungal agents have been the focus of attention these years. METHODS: Thirty-two FCZ-resistant C. albicans were selected as our test strains (MICs > or = 64 micrograms/ml). With 14-alpha-demethylase gene (ERG16 gene, target enzyme encoding gene of azoles) as our object, we chose six sets of primers from the ERG16 gene to amplify the interested fragments, and conducted Southern blot hybridization, restriction fragment length polymorphism (RFLP), and single strand conformation polymorphism (SSCP) analysis for the fragments which were amplified by the six sets of primers, and pre-resistant sensitive strains were used as controls. Three representative fragments, A66, D66 and E78, were selected to be cloned and sequenced. RESULTS: The polymerase chain reaction (PCR) amplification showed that several tested strains were negative for some primers. However, our Southern blot analysis reminded that their resistance did not result from the lack of target enzyme coding gene. SSCP analysis showed that differences were noted between the resistant and sensitive strains and inter-resistant strains. Statistical analysis showed that the most variable sequence lied in the amplifier of the sixth pair of primer, and all the tested 32 strains showed positive results. In the 11 mutation points we found, five resulted in amino acid alterations. It is likely that one or more mutational alterations (alone or in combination) might lead to the expression of an enzyme highly resistant to the inhibitory action of FCZ which in turn is responsible for the FCZ resistant trait in these strains. CONCLUSION: One or more mutational alterations might lead to the azole resistant trait in this strains.

Acquired Immunodeficiency Syndrome↗
PubMed1999

In vitro activities of five antifungal agents against pathogenic Exophiala species.

OBJECTIVES: To examine the in vitro activities of five antifungal agents against common pathogenic Exophiala species; to detect the minimum inhibitory concentration (MIC) discrepancies among different drugs and different species; to evaluate the role of the influence factors in MIC determination; and to establish a standard method for the antifungal susceptibility testing of Exophiala spp. METHODS: MICs of itraconazole (ICZ), fluconazole, ketoconazole, amphotericin B (AmB) and 5-flucytosine against 5 species (57 strains) of Exophiala spp were determined by modified NCCLS M27-A broth microdilution method. Two inoculum sizes (0.5 x 10(3)-2.5 x 10(3) CFU/ml and 0.5 x 10(4)-2.5 x 10(4) CFU/ml) and three incubation times (4, 7 and 10 days) were evaluated. The minimum fungicidal concentrations (MFC) of itraconazole against 20 Exophiala strains were also detected. RESULTS: All the tested Exophiala species were sensitive to AmB and ICZ. MICs varied among different species and drugs. Resistant strains to different drugs existed in this genus. The proper inoculum density was about 0.5 x 10(3) CFU/ml to 2.5 x 10(3) CFU/ml, and the 4-day incubation time was suitable for more than 90% of the strains. CONCLUSIONS: AmB or ICZ may serve as the first choice in treatment of phaeohyphomycosis. A standard microdilution procedure for MIC detection of Exophiala species is established in this experiment. The inoculum size and incubation time are the essential factors in the standardization of antifungal susceptibility testing of filamentous fungi. We hope this experiment may correlate well with the clinical treatment of phaeohyphomycosis caused by Exophiala species.

Amphotericin B↗
PubMed1999

[Detection of human immunodeficiency virus infection in tuberculosis patients].

OBJECTIVE: Combined infection of human immunodeficiency virus (HIV) and Mycobacterium tuberculosis (MTB) has attracted wide attention. This study was to find out infection of HIV and occurrence of AIDS in tuberculosis patients. METHODS: Primary screening was conducted in 2 973 inpatients with pulmonary tuberculosis by gelatin particle agglutination assay or rapid gold-labeled HIV 1 + 2 antibody assay. The HIV positive cases were sent to Beijing Municipal Center Laboratory for verification. RESULTS: Three HIV positive cases were detected among 2,973 pulmonary tuberculosis patients with the positive rate of 1.01 per thousand. Two were male and 1 female with average age of 30 years (23, 27, and 40 years respectively) accounting for 2.86 per thousand of the 21 - 41 age group, among which 1 infected through intravenous drug injection, 2 by heterosexual behavior. And all the 3 HIV positive cases had developed to be AIDS. CONCLUSIONS: Enough knowledge of the risk of combined HIV/MTB infection and high-degree alert should be emphasized in medical professionals involving in diagnosis, treatment and management of tuberculosis. Routine HIV antibody detection in high-risk tuberculosis patients for HIV infection, especially in young and middle-age tuberculosis patients, is helpful for early diagnosis and treatment of AIDS and avoiding its spreading.

Adult↗
PubMed1999

[The level of expression of adhesion molecules CD44v6 and E-cadherin in colorectal cancer and analysis of correlates with metastasis].

OBJECTIVE: To determine the expression of adhesion molecules CD44v6 and E cadherin in colorectal cancer and its relation with metastasis. METHODS: The expression of CD44v6 and E-cadherin in 32 patients with colorectal carcinoma was investigated using immunohistochemical staining, which was performed on surgical specimens. RESULTS: No significant correlation with CD44v6 and histologic type, TNM and Dukes staging was noted, but it was significantly correlated with lymph node and hematogenous metastasis. E-cadherin was strongly expressed in normal epithelium examined. However, E-cadherin expression in colorectal carcinoma was reduced (positive rate 46.9%). Metastatic colorectal carcinoma showed significant reduction (positive rate 20%). CONCLUSION: CD44v6, E-cadherin immunoreactivity are significantly correlated with lymph node and hematogenous metastasis.

Cadherins↗
PubMed1999

[Studies on immunization strategies for hepatitis B in different endemic areas of China].

OBJECTIVE: To compare the cost-benefit of immunization with hepatitis B (HB) vaccine in different endemic areas of HB and to explore the optimal strategy for it. METHODS: Cost-benefit analysis and comprehensive weighted score analysis (CWSA) were used to screen the optimal immunization strategy for low, medium and heavy endemic areas of HB. RESULTS: Significant economic benefit was obtained in Long-An County, Guangxi Zhuang Autonomous Region, Shanghai and Jinan, Shandong Province from HB immunization programs for infants. The greatest benefit cost ratio (BCR) was provided by the low-dose immunization strategy, which was 49.91, 54.53 and 37.68, respectively for heavy, medium and low endemic areas of HB. The maximal net benefit could be obtained by the high-dose immunization strategy with better immune protective efficacy. CWSA showed that the low-dose immunization strategy was the optimal one for HB immunization. CONCLUSION: It is suggested that the low-dose immunization strategy be implemented in undeveloped areas to obtain a greater BCR, and the high-dose one be implemented in more developed areas to obtain more net benefit and lower prevalence of hepatitis B surface antigen carriage.

China↗