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Biomedical subjects

H Xie

Publications and source records attributed to H Xie.

At least 109 records · Page 6Linked to original sources
PubMed2000

[Effects of methylmercury on intracellular free calcium content in cerebral cortical neurons].

OBJECTIVE: This study was conducted to explore effects and potential mechanism of methylmercury on concentration of intracellular free calcium (Ca(2+)) in the acutely isolated cerebral cortical neurons. METHODS: Calcium ion indicator Fura-2 two wave-length fluorophotometry was used to measure concentration of Ca(2+). RESULTS: (0.10 - 5.00) x 10(-6) mol/L of methylmercury could increase level of free intracellular Ca(2+) in cerebral cortical neurons significantly (P < 0.01), in a dose-response manner. Increase in intracellular free Ca(2+) of neurons caused by methylmercury associated with large influx of Ca(2+) outside cells and release of stored Ca(2+) inside cells, especially by influx of Ca(2+) outside cells. Influx of Ca(2+) outside cells associated with Ca(2+) channels regulated by receptor gate and potential gate, but not associated with sodium-dependent channel. CONCLUSION: Methylmercury lead to abnormal increase of intracellular free Ca(2+) in neurons, which is closely related to Ca(2+) channel.

Animals↗
PubMed2000

[The modulation of type I collagen and its receptor system on biological characteristics of osteoblasts].

This paper addresses the question whether type I collagen-receptor system is necessary for the functional activity of osteoblasts. Through blocking type I collagen-receptor system by type I collagen antibody or integrin alpha 2 beta 1 antibody, the proliferation of osteoblasts was studied by cell count, the apoptosis was studied by flow cytometry, and the mRNA expressions of type I collagen, integrin alpha 2 beta 1 and osteocalcin were also detected by RT-PCR techniques. When type I collagen-receptor system was blocked, osteoblasts showed high apoptosis rate, lower growth kinetics and weak mRNA expression of type I collagen, integrin alpha 2 beta 1 and osteocalcin; the blocking effect was reversible. It suggests that type I collagen-receptor system is necessary for osteoblastic phenotype. The biomaterials for bone tissue engineering should be constructed according to the extracellular matrix of osteoblasts, which supply normal extracellular environment for osteoblasts.

Apoptosis↗
PubMed2000

[Studies on antiplatelet aggregation and anticoagulant action of Curcuma phaeocaulis].

OBJECTIVE: To study the effects of Curcuma phaeocaulis Valeton on platelet aggregation and anticoagulant action. METHODS: Antiplatelet aggregation and anticoagulant action of Curcuma phaeocaulis Valeton of mice is observed in platelet aggregation and coagulant time. RESULTS: The experimental results show that Curcuma phaeocaulis Valeton can inhibit platelet aggregation, prolong time of mice coagulation. CONCLUSION: Antiplatelet aggregation and anticoagulant action of processed products with vinegar is the most powerful.

Animals↗
PubMed2000

Microsurgical treatment of Mooren's ulcer.

OBJECTIVE: To evaluate effect of microsurgery of lamellar keratoplasty (LKP) on Mooren's corneal ulcer. METHODS: The effect, postoperative astigmatism, postoperative vision, ulcer recurrence of postoperation, and surgical complications of two groups of consecutive Mooren's ulcer inpatients treated respectively by non-microsurgery of LKP and microsurgery of LKP were analyzed. RESULTS: There were significant differences of the effect, postoperative astigmatism, postoperative vision, ulcer recurrence of postoperation, and surgical complications between the two groups. The effect and postoperative vision of the microsurgery-treated group were better than those of the non-microsurgery-treated group. The postoperative astigmatism, ulcer recurrence of postoperation, and surgical complications of the microsurgery-treated group were less than those of the nonmicrosurgery-treated group. CONCLUSION: Microsurgery of LKP of Mooren's corneal ulcer can greatly improve the ulcer healing and postoperative vision, and reduce the surgical complication and the ulcer recurrence of postoperation.

Adolescent↗
PubMed2000

[A histochemical and immunohistochemical study of cornea and adjacent bulbar conjunctiva in Mooren's ulcer].

OBJECTIVE: To investigate immunopathologic changes of cornea and adjacent bulbar conjunctiva in Mooren's ulcer, and roles of macrophage, T lymphocyte, and VCAM-1 in the pathogeny of Mooren's ulcer. METHODS: The specimens of the cornea lesions and their adjacent bulbar conjunctiva taken from 18 active Mooren's ulcer cases who received resection of conjunctiva and lamellar keratoplasty surgery were studied with histochemical and labelled streptavidin biotin (LSAB) immunohistochemical techniques to investigate the expressions of CD68, CD3, CD4, CD8, CD1a, VCAM-1, HSP70, and TNF in the affected cornea and adjacent conjunctiva. RESULTS: Under the histochemical examination, infiltration of neutrophils, plasma cells, lymphocytes, and eosinophils were found in the affected cornea and conjunctiva. Degeneration and necrosis of corneal epithelium, Bowman's layer, collageneous fiber in stromal layer, and edema of conjunctiva were shown. Infiltration of a large number of macrophages and T lymphocytes in the affected cornea and adjacent conjunctiva were shown in LSAB immunohistochemical staining. The main infiltrating T lymphocytes were the CD4 positive cells. The CD4/CD8 ratio was significantly higher than that of normal contrals (P < 0.01). VCAM-1 was strongly expressed in the affected corneal and conjunctival epithelium. There were no significant differences for expressions of CD1a, HSP70, and TNF between the pathological specimens and normal contrals. CONCLUSION: The large number of infiltrating macrophages are responsible for the immunopathological damage caused by T lymphocyte infiltration, aberrant production of cytokikens and aberrant expression of HLA-DR antigen of Mooren's ulcer. There is an aberrant expression of VCAM-1 in the affected corneal and conjunctival epithelium. The role of VCAM-1 in the immunopathogenesis of Mooren's ulcer needs to be studied.

Adult↗
PubMed2000

[Determination of trace Pb and Cd in water treatment reagent by graphite furnace atomic absorption spectrometry].

The optimum conditions for the determination of trace Pb and Cd in water treatment reagent by graphite furnace atomic absorption spectrometry were studied in detail in this paper. The results show that the long and tedious pretreatment process was cut down by calibrating background with D2 lamp and NH4H2PO4 as matrix modifier. The determination limits were 0.65 microgram.L-1 and 0.12 microgram.L-1 for (Pb and Cd) and linear ranges were 0-50 micrograms.L-1, 0-20 micrograms.L-1 for Pb and Cd, respectively. Rate of recovery was 90%-110%. This method is accurate, quick and simple, and can be used successfully to determine actual samples.

Cadmium↗
PubMed1999

[Toxic effects of cooking oil fumes on testis of rats].

To investigate the toxic effects of inhaling cooking oil fumes (COF), 30 male SD rats were submitted to inhaling COF at a constant concentration and duration (35-53 mg/m3, 30 min/d) for different length of time (20, 40 and 60 days), and examined for change in body weight, spermtogenesis and content of trace elements in their testes. The results indicated that the body weight and the ratio of gonad to body weight in rats inhaling COF for 40 and 60 days were lower than those in the controls (P < 0.05). Fewer alive sperms and more malformed or dead sperms were fond in the epididymis of rats exposed to COF for 40 and 60 days. Among the four trace elements(Zn, Mn, Cu, Fe) studied, the content of Zn in the testis was found to be significantly decreased and that of Mn significantly increased in the rats exposed to COF for longer periods. There existed a time-effect relationship in all of the above findings. The results suggested that inhaling COF was significantly toxic to male gonads, and the imbalance of Zn, Mn might be contributive to the damage of testis.

Animals↗
PubMed1999

Acquisition of selectin binding and peripheral homing properties by CD4(+) and CD8(+) T cells.

Different T cell subsets exhibit distinct capacities to migrate into peripheral sites of inflammation, and this may in part reflect differential expression of homing receptors and chemokine receptors. Using an adoptive transfer approach, we examined the ability of functionally distinct subsets of T cells to home to a peripheral inflammatory site. The data directly demonstrate the inability of naive T cells and the ability of effector cells to home to inflamed peritoneum. Furthermore, interleukin (IL)-12 directs the differentiation of either CD4(+) or CD8(+) T cells into effector populations that expresses functional E- and P-selectin ligand and that are preferentially recruited into the inflamed peritoneum compared with T cells differentiated in the presence of IL-4. Recruitment can be blocked by anti-E- and -P-selectin antibodies. The presence of antigen in the peritoneum promotes local proliferation of recruited T cells, and significantly amplifies the Th1 polarization of the lymphocytic infiltrate. Preferential recruitment of Th1 cells into the peritoneum is also seen when cytokine response gene 2 (CRG-2)/interferon gamma-inducible protein 10 (IP-10) is used as the sole inflammatory stimulus. We have also found that P-selectin binds only to antigen-specific T cells in draining lymph nodes after immunization, implying that both antigen- and cytokine-mediated signals are required for expression of functional selectin-ligand.

Adoptive Transfer↗
PubMed1999

Acetylcholinesterase clustering at the neuromuscular junction involves perlecan and dystroglycan.

Formation of the synaptic basal lamina at vertebrate neuromuscular junction involves the accumulation of numerous specialized extracellular matrix molecules including a specific form of acetylcholinesterase (AChE), the collagenic-tailed form. The mechanisms responsible for its localization at sites of nerve- muscle contact are not well understood. To understand synaptic AChE localization, we synthesized a fluorescent conjugate of fasciculin 2, a snake alpha-neurotoxin that tightly binds to the catalytic subunit. Prelabeling AChE on the surface of Xenopus muscle cells revealed that preexisting AChE molecules could be recruited to form clusters that colocalize with acetylcholine receptors at sites of nerve-muscle contact. Likewise, purified avian AChE with collagen-like tail, when transplanted to Xenopus muscle cells before the addition of nerves, also accumulated at sites of nerve-muscle contact. Using exogenous avian AChE as a marker, we show that the collagenic-tailed form of the enzyme binds to the heparan-sulfate proteoglycan perlecan, which in turn binds to the dystroglycan complex through alpha-dystroglycan. Therefore, the dystroglycan-perlecan complex serves as a cell surface acceptor for AChE, enabling it to be clustered at the synapse by lateral migration within the plane of the membrane. A similar mechanism may underlie the initial formation of all specialized basal lamina interposed between other cell types.

Acetylcholinesterase↗
PubMed1999

Characterization of the mammalian septin H5: distinct patterns of cytoskeletal and membrane association from other septin proteins.

The mechanisms controlling cytokinesis during yeast budding and animal cell fission appear quite different, yet both require members of the septin protein family. Mammalian homologs of this novel family of GTPases have been identified but little is known about their properties or functions. Using an antibody specific for the mammalian septin H5, we show that this protein is expressed at distinct levels in a variety of tissues. Tissue expression levels in different tissues did not coincide with those of the only previously characterized mammalian septin Nedd5. H5, like Nedd5, localizes to the cleavage furrow in mitotic fibroblast cells but in non-mitotic cells these proteins associate with actin filaments in different ways. Nedd5 predominantly localizes with stress fibers, but only associates with central portions of the microfilament bundles. In contrast, H5 associates with the entire length of the stress fibers and the cortical actin network. Conditions that disrupt the actin cytoskeleton also disrupt the filamentous patterns of both Nedd5 and H5, resulting in a punctate cytoplasmic pattern. Cell fractionation revealed that H5 co-fractionated with actin, while Nedd5 was predominantly restricted to the membrane fraction. Co-immunoprecipitation experiments revealed that although H5 will co-precipitate with Nedd5, the precipitation is not quantitative. Taken together, these results not only show that H5 behaves like a septin, but also demonstrate that individual septin proteins have distinct properties, suggesting that they may play different roles in cytokinesis and in other stages of the cell cycle.

3T3 Cells↗
PubMed1999

Color Doppler energy and related quantitative analysis of gestational trophoblastic tumors.

OBJECTIVE: To assess the reliability of color Doppler energy (CDE) and a related quantitative analysis for detection and follow-up of uterine involvement in gestational trophoblastic tumor. METHOD: CDE was performed in 19 patients with trophoblastic tumor, in 25 women in early pregnancy and 25 non-pregnant women. The blood flow area ratio (BFAR) in CDE was used as an index representing uterine involvement. In nine of the 19 patients, BFAR was measured before, during and at termination of chemotherapy. RESULT: The BFAR (mean +/- S.D.) of uterine profiles in 19 patients (39.9 +/- 1.3%) was significantly higher than that in 25 pregnant women (24.6 +/- 10.1%, P = 0.002) and in 25 non-pregnant women (14.8 +/- 5.7%, P = 0.001). In the follow-up of nine patients, when beta-hCG was less than 3.1 ng/ml during the treatment, the BFAR (38.7 +/- 11.9%) decreased below that (44.2 +/- 14.6%) seen prior to treatment (P = 0.009) and was much lower at termination of treatment (27.5 +/- 12.3%, P = 0.048). CONCLUSION: These data support the use of CDE and the related quantitative analysis as a new method for detecting and follow-up of uterine involvement in patients with trophoblastic tumors.

Adult↗
PubMed1999

Alpha-fetoprotein enhances the proliferation of human hepatoma cells in vitro.

Although the biological functions of alpha-fetoprotein ( AFP ) have been extensively studied, little is known about its effect on tumor cell growth. Our previous work has found that human AFP significantly stimulates the growth of mouse hepatoma cells in vitro. The purpose of the present study is to observe the effect of AFP on the proliferation of human hepatoma cells in vitro. Using a MTT- microculture tetrazolium assay, we found that the proliferation of human hepatoma cells was enhanced by in vitro treatment of AFP. However, the same concentrations of AFP had no effect on HL - 60 human leukemia cell proliferation, indicating that the human hepatoma cell proliferation - promoting role of AFP was not simply due to non-specific addition of exogenous protein and the proliferation enhancement of AFP showed certain tumor cell specificity. On the other hand, the growth stimulation of AFP could be diminished by rabbit anti - human AFP antibody. The anti- AFP antibody alone suppressed the growth of BEL - 7404 human hepatoma cells, not affecting HL - 60 cell proliferation. BEL - 7404 cell proliferation was not inhibited by normal rabbit immunoglobulins to demonstrate the specificity of anti-AFP effect. Taken together, it is concluded that AFP enhances the proliferation of human hepatoma cells in vitro, and this effect is seemingly mediated by an AFP/receptor autocrine pathway.

Antibodies↗
PubMed1999

The septin CDCrel-1 binds syntaxin and inhibits exocytosis.

Septins are GTPases required for the completion of cytokinesis in diverse organisms, yet their roles in cytokinesis or other cellular processes remain unknown. Here we describe studies of a newly identified septin, CDCrel-1, which is predominantly expressed in the nervous system. This protein was associated with membrane fractions, and a significant fraction of the protein copurified and coprecipitated with synaptic vesicles. In detergent extracts, CDCrel-1 and another septin, Nedd5, immunoprecipitated with the SNARE protein syntaxin by directly binding to syntaxin via the SNARE interaction domain. Transfection of HIT-T15 cells with wild-type CDCrel-1 inhibited secretion, whereas GTPase dominant-negative mutants enhanced secretion. These data suggest that septins may regulate vesicle dynamics through interactions with syntaxin.

Animals↗
PubMed1999

The pharmacokinetics of lamivudine in healthy Chinese subjects.

AIMS: The purpose of this study was to investigate the pharmacokinetics of daily oral doses of lamivudine administered to healthy Chinese subjects for 1 week. METHODS: Twenty-four subjects were enrolled, 12 males and 12 females, all between the ages of 18 and 40 years. After an overnight fast, all subjects received a single oral dose of 100 mg lamivudine. Blood was obtained before lamivudine administration and at regular intervals to 24 h post dose. Subsequent doses were given once daily for a total of 7 days. On the last day another full pharmacokinetic profile was obtained to 24 h postdose. Timed urine collections were performed for all subjects on day 1 only. Pharmacokinetic parameters were calculated by using standard non compartmental techniques. RESULTS: Lamivudine was well absorbed in all subjects (tmax 1 h). On day 1 and day 7 the overall geometric mean Cmax was 1304 and 1385 ng ml-1, and AUC(0,24h) was 4357 and 4353 ng ml-1 h, respectively. On average 78% of the lamivudine dose was recovered in urine as parent compound. Pharmacokinetic parameters were very similar between male and female subjects, between day 1 and day 7 and in comparison with data obtained in many other pharmacokinetic studies. CONCLUSIONS: This study demonstrated that the pharmacokinetics of lamivudine are essentially identical between Chinese and Caucasian subjects, and between males and females. It confirms 100 mg lamivudine is an appropriate dose for use in Chinese patients, providing adequate exposure for optimal antiviral effect.

Adult↗
PubMed1999

Promoter architecture of the Porphyromonas gingivalis fimbrillin gene.

Porphyromonas gingivalis fimbriae can mediate adherence to many of the available substrates in the oral cavity. Expression of P. gingivalis fimbriae is regulated at the transcriptional level by environmental signals, such as temperature and hemin concentration. The arrangement of the upstream promoter and regulatory sequences required for transcription and control of the fimbrial structural gene (fimA) was investigated. Primer extension analysis demonstrated that the transcriptional start site of the fimA gene is located 41 bp upstream from the translational start codon. A region (upf) spanning 648 bp upstream of the start codon to 44 bp downstream of the translational start site was cloned upstream of a promoterless lacZ reporter gene. A series of deletion and base substitution mutations were then generated in the upf region. The constructs were introduced into the chromosome of P. gingivalis, and promoter activity measured by assaying levels of beta-galactosidase. The results showed that fimA contains sequences resembling sigma70 promoter consensus sequences, consisting of a -10 region (TATGAC) located at -18 to -23 and a -35 region (TTGTTG) located at -41 to -46 from the transcriptional start point. The AT-rich upstream sequences spanning bases -48 to -85 and bases -90 to -240 were required for full expression of the fimA gene, indicating the existence of positive regulation regions. Moreover, the -48 to -64 region may constitute an UP element, contributing to promoter activity in P. gingivalis. Thus, our data suggest that the P. gingivalis fimA gene has a transcription complex consisting of -10 and -35 sequences, an UP element, and additional AT-rich upstream regulatory sequences.

Bacterial Proteins↗
PubMed1999

Oxidized low-density lipoprotein enhances myogenic tone in the rabbit posterior cerebral artery through the release of endothelin-1.

BACKGROUND AND PURPOSE: Cerebral arteries develop stretch-induced myogenic tone, which plays an important role in the regulation of blood flow to the brain. Although the effect of oxidized LDL (Ox-LDL) on many aspects of the vascular endothelial and smooth muscle cell function have been extensively investigated, its influence on myogenic activity has not been studied. METHODS: The effect of Ox-LDL on the myogenic tone that develops in the perfused rabbit posterior cerebral artery at intramural pressures between 40 and 90 mm Hg was examined. RESULTS: Ox-LDL (10 microg/mL) significantly enhanced myogenic tone by 21.4+/-6.1% to 28.5+/-1.8% at 60 to 90 mm Hg pressure (P<0.05) but had no influence on norepinephrine- (0.5 to 1 micromol/L) and KCl (20 mmol/L)-induced constriction. Ox-LDL was effective whether the artery was exposed to it from the intraluminal or the extraluminal surface. Lysophosphatidylcholine (10 micromol/L), a lipid component of Ox-LDL, had an equivalent potentiating effect. Native LDL (100 microg/mL) was inactive. The myogenic tone-potentiating effect of Ox-LDL was abolished by endothelium removal but was not influenced by the NO synthase inhibitor N(G)-nitro-L-nitro-arginine methyl ester (50 micromol/L). This effect was reversed by the endothelin-1 (ET-1) antagonist BQ-123 (1 micromol/L). This concentration blocked 1 to 3 nmol/L ET-1-induced constriction without altering constriction induced by 40 mmol/L KCl. The potentiating effect was suppressed by the specific protein kinase C inhibitor chelerythrine (1 micromol/L). CONCLUSIONS: Ox-LDL enhances myogenic tone through the release of ET-1 from the endothelium of the rabbit posterior cerebral artery.

Alkaloids↗