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Biomedical subjects

X Chen

Publications and source records attributed to X Chen.

At least 595 records · Page 33Linked to original sources
PubMed2000

[Relationship between folate, vitamin B12, total plasma homocysteine and mutation of reductase].

OBJECTIVE: To study relationship between serum and red blood cell (RBC) folate, serum vitamin B(12) (VB(12)), total plasma homocysteine (tHcy), thermolabile genotypes, and activity of methylene-tetrahydrofolate reductase (MTHFR). METHODS: Thirty-four non-pregnant and healthy mothers who gave birth to babies with neural tube defects (NTDs) and 42 mothers to normal babies previously were chosen. Plasma tHcy, RBC and serum folate, serum VB(12), activity of MTHFR and thermolabile genotypes were determined for all of them. RESULTS: There was no significant difference in plasma tHcy, RBC and serun folate between case and control groups. Serum VB(12) was significantly lower in mothers of babies with NTDs than in those with normal ones. Plasma tHcy correlated with RBC folate inversely (P < 0.05). Mean plasma tHcy for thermolabile homozygous mutation of MTHFR was significantly higher than that for either heterozygous mutation or wild homozygous mutation (P < 0.001). There was no significant difference in serum folate between groups with varied MTHFR genotypes. Plasma tHcy was slightly greater in those with lower serum folate than in those with higher one, and correlated inversely with activity of MTHFR. CONCLUSIONS: Increase in plasma tHcy correlates with homozygous mutation of thermolabile MTHFR and decrease in activity of MTHFR. Higher level of folate in the body can interfere the relationship between plasma tHcy and activity of MTHFR.

Adult↗
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

[A report of 115 cases of amputation after electric injury].

OBJECTIVE: To analyze the main features of amputation subsequent to electric injury. METHODS: One hundred and fifteen cases of amputation were analyzed with the purpose to define the indication, the optimal level, operational methods and the prognosis. RESULTS: The incidences of amputation in this group were 45.4% for upper and 14.9% for lower extremities, respectively. The indications were total necrosis of the extremities, secondary necrosis of the extremities due to the thrombosis, bleeding and rupture of the major supplying arteries and failure to restore severely injured tissue. The commonest amputation levels were the mid third and the upper third of the forearms. The primary healing rate was 63.5%. CONCLUSION: It was very important to identify the optimal indications, the proper levels and operational methods for the amputation after electric injury, so as to make stumps more suitable for the installation of artificial limbs to restore better function.

Amputation, Surgical↗
PubMed2000

[The mechanisms of inhibitory effect of bufalin on human leukemia cells].

OBJECTIVE: To study the mechanism of bufalin on human leukemia cell inhibition. METHODS: HL-60 cells were treated with bufalin at different concentrations. The growth inhibition was analysed by MTT assay, cell apoptosis by light microscopy, transmission electron microscopy, flow cytometry, TUNEL labeling method and agarose gel electrophoresis. RESULTS: (1) Treatment of HL-60 cells with bufalin remarkably inhibited the cell growth, the IC(50) value of bufalin for HL-60 cells was 0.025 micromol/L. (2) Apoptosis of HL-60 cells could be efficiently induced by bufalin at concentration of 0.010 micromol/L or higher. (3) Bufalin induced apoptosis of HL-60 cells in a dose- and time-dependent manner. (4) With G(1) phase cells decreasing, S phase cells increased, and then apoptotic cells increased with a diminution of S phase cells. (5) Bufalin-induced apoptosis of HL-60 cells was inhibited by ZnCl(2), an inhibitor of endonuclease, but not by cycloheximide, an inhibitor of protein synthesis. CONCLUSION: Bufalin could efficiently induce apoptosis of HL-60 cells, especially the S phase cells.

Apoptosis↗
PubMed2000

[Effects of yanggan xifeng recipe on changes of neurological behavior of rat of Parkinson's model].

OBJECTIVE: To investigate the effect of Yanggan Xifeng Recipe (YGXFR) for nourishing Liver to calm down endogenous Wind on neurological behavior of Parkinson's disease (PD) rat model. METHODS: PD rat model was established by destroying the substantia nigra condense area (SNc) and ventral tegmental area (VTA) unilaterally with 6-hydroxy dopamine (6-OHDA). The rats for control were injected in the same site with the same dose of normal saline. The animals were randomly divided into 3 groups (7 in each group), the control group, the model group and the TCM treated group. Staircase test and rotation test induced by apomorphine were performed in all groups and compared. RESULTS: The staircase test demonstrated that, after being treated with YGXFR, the food pellets intake were increased compared to model group (P < 0.05), and their rotation induced by apomorphine was lessened (P < 0.01). CONCLUSION: YGXFR could recover the neurological behavior deficits of PD rat models.

Animals↗
PubMed2000

[Study on mechanism of Shenle and Fragmin in preventing and treating glomerulosclerosis in rats].

OBJECTIVE: To study the effects of Shenle and Fragmin on the degradation of extracellular matrix metalloproteinase-9 (MMP-9) and tissue inhibitors of metalloproteinase-1 (TIMP-1) in the remnant kidneys of 5/6 nephrectomized rats treated with Shenle and Fragmin. METHODS: The model of focal and segmental glomerulosclerosis was made by 5/6 nephrectomy in Wistar rats. After being treated with Shenle (4 g.kg-1.d-1) or Fragmin (1000 IU.kg-1.d-1) for 20 weeks, the blood pressure, proteinuria, serum creatinine, lipids, renal pathological change of remnant kidney of the model animals were examined, and the mRNA expression of MMP-9, TIMP-1 and type IV collagen in the remnant kidney were also detected. RESULTS: Shenle and Fragmin could significantly reduce the blood pressure, proteinuria, serum creatinine and lipids, alleviate the pathologic change of kidney tissue, decrease the type IV collagen, MMP-9 deposition. Shenle and Fragmin down-regulated the mRNA expression of MMP-9 by 30.0% and 28.5% and TIMP-1 expression by 59.3% and 55.0% in the remnant kidney of the 5/6 nephrectomized rats respectively. CONCLUSION: Shenle and Fragmin might ameliorate glomerulosclerosis through modulating MMP-9/TIMP-1 gene expression, alleviate the abnormal metabolism and accumulation, promote extracellular matrix degradation in glomeruli remodeling, it might be the important mechanism of Shenle and Fragmin in treating glomerulosclerosis.

Animals↗
PubMed2000

[Observation of the modulatiny effect of histamine on intestinal barrier function].

The model of CaCo2 cell monolayer system has been generally accepted as a standard method for in vitro study of the relationship between the epithelium and microbial invasion. In this study, we set up the model with a simplified method and used it to observe if histamine, which is an important inflammatory factor in gastroenteric tract, can offer some barrier protection from E. coli invasion. After two weeks' routine incubation, the established CaCo2 cells monolayer systems were co-cultured with 1 x 10(-8) mmol/L, 1 x 10(-7) mmol/L and 1 x 10(-6) mmol/L histamine DMEM for 2 hours, and with frank DMEM as control for the same length of the time. For observation on time course effect of histamine, the co-cultures with 1 x 10(-6) mmol/L histamine DMEM were kept up for 0.5, 1.0, 2.0, 4.0 and 18.0 hours. Bacterial invasion ws assessed by quantitating the number of E. coli within the coultured epithelial cells. The results showed that histamine significantly inhibited the invasion of E. coli to epithelial cells(P < 0.05). The colony counts in co-cultures with 1 x 10(-7) mmol/L and 1 x 10(-8) mmol/L histamine DMEM were 52.5, 30.3 and 91.3 respectively, compared with 563 in control group. In the study of the time course effect of histamine, the colony conuts of co-culture with histamine DMEM for 0.5, 1.0, 2.0, 4.0 and 18.0 hours were 135.5, 64.0, 29.5, 36.0 and 22.5 respectively. It was concluded that histamine can enhance the protective barrier function of intestinal epithelium against E. coli invasion.

Bacterial Translocation↗
PubMed2000

[A study on the changes of blood levels of type III procollagen and type IV collagen in relation to artery blood gas and lung function in patients with cor pulmonale].

This study was conducted to explore the changes of PC III (type III procollagen) and C IV (type IV collagen) in the serum in patients with chronic pulmonary heart diseases. The blood levels of PC III and C IV in 25 patients with chronic pulmonary heart diseases and 20 normal subjects were measured by radioimmunoassay and were analysed in relation with the artery blood gas and pulmonary function parameters. The results revealed that the blood levels of PC III and C IV in the patients were significantly higher than those in normal subjects, and were negatively correlated with PaO2, FEV1%, MBC and MMEF (P < 0.05, P < 0.01). The results suggest that the blood levels of PC III and C IV of patients with chronic pulmonary heart diseases are significantly increased and significantly correlated with pulmonary function damage and hypoxia.

Aged↗
PubMed2000

[The effects of mechanical stretching on DNA synthesis of human periodontal ligament fibroblasts].

This study was aimed at the effects of mechanical stretching on DNA synthesis of human periodontal ligament fibroblasts(PDLF). Flow cytometry(FCM) was used to examine the proliferative activities of PDLF grown on the flexible culture dishes subjected to mechanical stretching. The results showed that in the range of 0.5%-8%, mechanical stretching could stimulate DNA synthesis 2 hours after the cells had been subjected to stretches. DNA synthesis reached the peak in the 6 hours. The effect of 2% stretching was more significant. As time went by, the mitogenic effect of stretch was decreased. These findings suggest that mechanical stretching can stimulate DNA synthesis of PDLF.

Cell Cycle↗
PubMed2000

[Study on sensitivity of neuroglioma to chemotherapeutic drugs].

In this study, the chemosensitivity of 36 cases' fresh neuroglioma specimens was examined in vitro with MTT assay. The separation method for single tumor cell, the number of planting of cells, and the dosage and acting time of drugs, which have effects on the results of MTT assay, were studied systematically. On the basis of this experiment, we established a screening method for the chemosensitivity of neuroglioma; it is accurate, rapid, and simple. At the same time, the results showed that neuroglioma was more sensitive to the chemotherapeutic drugs Vm26, DDP and MMC, and the sensitivity varied with not only the drugs but also the individuals.

Antineoplastic Agents↗
PubMed2000

[Effects of selenium and zinc on the DNA damage caused by fluoride in pallium neural cells of rats].

To investigate the effects of fluoride on DNA damage as well as the effects of selenium and zinc against fluoride respectively or jointly in pallium neural cells of rats, single cell gel electrophoresis was used to detect the DNA damage of neural cells prepared in vitro. The results showed that the degree of DNA damage in the fluoride group and the selenium group were significantly greater than that in control group(P < 0.01). The damage in the fluoride group was even more serious. The damage in the fluoride + selenium group and fluoride + zinc group was slighter than that in the fluoride group but with no significant difference. The extent of DNA damage in the fluoride + selenium + zinc group was significantly slighter than that in the fluoride group(P < 0.05). It suggested that fluoride and selenium could induce DNA damage in pallium neural cells of rats respectively. Moreover, the joint antagonistic effect of selenium and zinc against fluoride was more obvious.

Animals↗
PubMed2000

[Domoic acid and glutamate receptors].

Domoic acid is a kind of neurotoxin produced by diatoms and accumulated in food chain, which is harmful to the human health. The N-methyl-D-aspartate receptor and kainic acid/alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor could be activated by domoic acid. The concentration of the intracellular Ca2+ could be elevated, causing a series of physiological and biochemical changes. The possible mechanisms of neurotoxicity induced by domoic acid through glutamate receptors are discussed.

Animals↗
PubMed2000

[Determination of ochratoxin A by ELISA].

The determination of ochratoxin A by Enzyme-linked immunosorbent assay (ELISA), including the method of preparation of antigen and antibody, and the promising of ELISA in mycotoin determinations was introduced.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

[The effect of fibrin sealant on dental pulp for pulp capping in experimental dogs].

OBJECTIVE: To investigate the pulp tissue reaction and reparative dentine formation of dog pulp capped with Fibrin Sealant (FS). METHODS: The fibrin was from a tisseel Kit (Immuno AG, Vienna, Austria) consisting of solution A (freeze-dried human fibrinogen, factor XIII, Aprotinine) and solution B (thrombin powder, calcium chloride) with 0.02 ml from each for each tooth. The Ca(OH)2 paste (Calar, China) was served as the control. Forty nine cuspid, premolar and molar teeth in 4 adult dogs weighed 11-13 kg were used. Surgical anesthesia was obtained by muscle injection of 3% sodium pentobarbital (1 ml/kg). The pulp were exposed by using sterile high-speed rotary cutting instruments with water-cooling. The pulps were treated with 0.02 ml fibrin or Ca(OH)2 paste respectively. The cavity was filled with zine phosphate cement. The animals were killed at intervals of 1, 4, 6, 9 weeks after surgery and perfused with phosphate-buffered saline followed by 10% formalin in phosphate-buffered saline. The jaws were resected and the samples prepared by removing each experimental tooth in block, further fixing them by immersion in 10% formalin in phosphate-buffered saline. The specimen were processed for histologic examination. Serial sections (5 nm thick) were made, stained with hematoxylin and eosin, examined using a light microscope. RESULTS: 7 days after operation, the samples treated with the FS showed no hemorrhage and degeneration of pulp tissue and a small amount inflammatory cells near the wounds. The samples treated with Ca(OH)2 showed hemorrhage and degeneration (2/6) and a large amount inflammatory cells near the wounds. 28 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was nearly recovered. Dentin bridges were observed in 2 out of 6 cases treated with Ca(OH)2. 42 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was totally recovered. Dentin bridges were observed in 2 out of 7 cases of pulp treated with FS and four out of 6 cases treated with Ca(OH)2. 63 days after operation, pulp health of teeth treated with FS and Ca(OH)2 was soundly resumed. The dentine bridge was observed in 4 out 6 cases of pulp treated with the FS and in all 6 cases treated with Ca(OH)2. CONCLUSION: FS has no dentin inducing activity, but can enhance exposed pulp healing, so FS can be served as a promised pulp capping agent.

Animals↗
PubMed2000

[Oncocytic carcinoma of salivary gland].

OBJECTIVE: To study the histological and immunohistochemical characteristics of oncocytic carcinoma of salivary gland. METHODS: 7 cases of oncocytic carcinoma of salivary gland were investigated by HE, PAS, PTAH staining and immunohistochemistry. RESULTS: Among the cases, 4 were male and 3 were female. The average age was 49 years old. 3 cases occurred in the parotid, 1 cases in submandibular, 1 cases in sublingual and 2 cases in minor salivary gland of palate. Investigated histologically, the tumour cells are characterized by oncocyte. The evidence of cellular atypia, obviously increased mitoses and infiltrative growth pattern are indicative of malignancy. Immunohistochemically, alpha 1-ACT, alpha 1-AT, LF, TF and CEA were all strongly positive in the normal salivary cells and adenolymphoma, while in oncocytic carcinoma, alpha 1-ACT and alpha 1-AT were moderate positive and LF, TF and CEA were light positive. CONCLUSION: 7 cases were characterized by oncocyte and showing infiltrative growth, alpha 1-ACT, alpha 1-AT, LF, TF, CEA were positive in oncocyte.

Adenocarcinoma↗
PubMed2000

[Study on chemosensitivity assay in vitro in the peripheral blood lymphocyte and the tumor cells].

In this study, the MTT method was used to test the sensitivity of the peripheral blood lymphocyte and the tumor cells of 35 patients with neuroglioma to 15 kinds of anti-cancer drugs. The results showed that the peripheral blood lymphocyte and the tumor cells were more sensitive to chemotherapeutic drugs Vm26 and TAX, and sensitive to DDP, Me-CCNU, EADM, ADM, MMC, HCPT, but not sensitive to MTX, ACR, VP-16, VCR and BLM. There were no statistical differences in the rate of sensitivity to the above-mentioned drugs between the peripheral blood lymphocyte and the tumor cells. These results prompt that the chemosensitivity test of the peripheral blood lymphocyte may take the place of the tumor cells for reference to choosing chemotherapeutic drugs in clinical practice.

Antineoplastic Agents↗
PubMed2000

[Construction of genomic library from L. lactis AL2 and isolation of entire nisin biosynthesis gene cluster].

A total DNA library of Lactococcus lactis AL2 with high yield of nisin was successfully constructed using lambda EMBL3 as vector. 3900 plaques were obtained, which is much more than the required number of recombinants that represents an entire L. lactis genome according to Clarke and Carbon formula. Southern hybridization, PCR amplification and DNA sequencing revealed that the entire nisin biosynthesis gene cluster was isolated from the constructed library.

Base Sequence↗