Biomedical subjects

D Chen

Publications and source records attributed to D Chen.

At least 145 records · Page 8Linked to original sources

PubMed2001

Removal of color substances using photocatalytic oxidation for membrane filtration processes.

This study aims to remove the color substances, which normally cause difficulties in membrane filtration processes due to fouling using heterogeneous UV/TiO2/H2O2 reactor. It is confirmed that the technique used in this study was effective to remove TOC at 38% and color400 at 89% within 150-min irradiation. The experiment results showed that low concentrations of hydrogen peroxide dosage (less than 0.016 M) to UV/TiO2 system accelerated the TOC and Color400 removal rate from 9% to 38% and 40% to 89% respectively, while over-dosage made this positive effect decline. The humic acid solution treated by photo catalytic oxidation in UV/TiO2/H2O2 reactor did not change the zeta potential on membrane surface and membrane rejection rate.

Coloring Agents↗

PubMed2001

[The cytotoxic effects of the adriamycin magnetic albumin microspheres combined with external magnetic fields on the malignant tumor cells].

This study sought to assess the inhibitory effects of the adriamycin magnetic albumin microspheres (ADM-MAMs) on Walker-256 malignant tumor cells in vitro induced by the permanent magnetic fields. The cultured Walker-256 cells were divided into three groups; the group of ADM-MAMs combined with magnetic fields, the group of AMD-MAMs without magnetic fields, and ADM group. The growth states of the cells were observed and photographed under the inverted microscope. The inhibitory rates(IR) were assayed by the modified MTT colorimetric method. The results showed that the IR of the ADM-MAMs group were similar to those of the ADM group (P > 0.05), but the group of ADM-MAMs combined with magnetic fields had obviously higher IR and significant changes of the cells' shapes. These findings indicate that the anticancer effect of ADM-MAMs on malignant tumor cells is similar to that of ADM, and such effect can be increased by the combined use of ADM-MAMs and external magnetic fields.

Albumins↗

PubMed2001

Joint action of chemicals in algal toxicity tests: influence of response level and dose-response regression model.

The joint toxicity of nonylamine and decylamine and of atrazine and decylamine was evaluated in assays with the green alga Selenastrum capricornutum based on an isobologram method. In this method, curves of constant response, isoboles, are plotted versus concentrations of two toxicants. The response parameter was growth rate based on biomass, and several response levels were used. Dose-response curves were developed for dilution series using fixed ratios between concentrations in toxic units of the compounds. Probit and Weibull dose-response curves were then determined by nonlinear regression. A model for isoboles for partially similar action was used when applicable. The no-effect concentration (NEC or EC0) was estimated based on a newly proposed model containing median effective concentration (EC50) and EC0 as explicit variables. Results show that nonylamine and decylamine are nearly concentration additive at EC50 and EC10 (similarity parameter lambda = 0.70-0.76) and to a lesser extent at EC0. By contrast, the mixtures of atrazine and decylamine show antagonism in that atrazine acts as an antidote to decylamine. The shapes of these isoboles are independent of response level. The EC50 values (mg/L) for chemicals acting singly were 0.090 (nonylamine), 0.039 to 0.044 (decylamine), and 0.225 (atrazine). In order to determine NEC effectively, the level of inhibition must be fairly low, with observed growth rates between 0.6 and 1.0 times the average growth rate of the controls.

Amines↗

PubMed2001

[Cytotoxicity of the strontium-substituted hydroxyapatite evaluated by MTT colorimetry].

This study was conducted to evaluate the cytotoxicity of strontium-substituted hydroxyapatite by methyl thiazolyl tetrazolium (MTT) colorimetry. We used the MTT method to assay the cytotoxicity of the strontium-substituted hydroxyapatite containing different strontium concentrations (1%, 5%, 10%, 100% Sr2+) and the pure hydroxyapatite. The results showed that the cytotoxicity scores of the different materials were grade 0 or grade 1. These led us to the conclusion that strontium-substituted hydroxyapatite has good biocompatibility.

Animals↗

PubMed2001

Control of secretion from rat stomach ECL cells in situ and in primary culture.

The acid-producing part of the stomach is rich in peptide-hormone-producing endocrine/paracrine cells of different types. In birds and all mammals studied, ECL cells constitute the quantitatively predominant endocrine cell population in this location. They produce histamine and an as yet unidentified peptide hormone. The paracrine action of the ECL cells is to provide histamine to mediate the stimulating effect of gastrin on the acid-secreting parietal cells: the gastrin-ECL cell-parietal cell axis. Secretion of histamine from the ECL cells was studied in intact conscious rats subjected to gastric submucosal microdialysis and using isolated cells in primary culture. The microdialysis experiments revealed that ECL-cell histamine can be mobilized by the local infusion of gastrin, pituitary adenylate cyclase-activating peptide (PACAP), vasoactive intestinal peptide (VIP), peptide YY (PYY), met-enkephalin, endothelin and noradrenaline/adrenaline. While gastrin and met-enkephalin induced a sustained elevation of the submucosal histamine concentration, endothelin, PYY, PACAP, VIP, and noradrenaline/adrenaline induced a transient elevation. Somatostatin, galanin and the prostanoid, misoprostol, inhibited gastrin-stimulated histamine mobilization. Studies of isolated ECL cells (80-90% purity) showed gastrin, PACAP and VIP to stimulate histamine secretion and somatostatin, galanin and misoprostol to inhibit gastrin-stimulated secretion. At present, it seems unlikely that metenkephalin, endothelin, adrenaline and PYY act directly on the ECL cells in situ since the effects could not be reproduced with isolated ECL cells. Clearly, the ECL cells operate under the multifactorial control of circulating hormones, local hormones, catecholamines, neuropeptides and inflammatory mediators.

Animals↗

PubMed2001

[Therapeutic effects of nitroglycerin on pregnancy induced hypertension].

OBJECTIVE: To evaluate the effects and possibility of nitroglycerin on Pregnancy induced hypertension (PIH) treatment. METHODS: In comparison with the third trimester normal pregnant women (Normal group) (n = 11), 34 moderate/severe PIH cases were divided into three groups: PIH treated only with magnesium sulfate (Mg group) (n = 11); PIH treated only with nitroglycerin (Ng group) (n = 11); and PIH treated with Mg + Ng (Combination group) (n = 12). The endothelial nitric oxide synthase (eNOS) in placenta was investigated immunohistochemically and quantitatively. Data such as platelet aggregation (PAg), umbilical artery of S/D ratio and resistance index (RI) with color Doppler and the effect of decrement of blood pressure on PHI groups were evaluated. RESULTS: In comparision with Normal group, (1) the quantity of eNOS of PIH cases was significantly lower (P < 0.01). (2) umbilical artery S/D ratio and RI in Ng group were significantly lower after introvascular drip of Ng (P < 0.05). (3) Pag in Ng group and Combination group decreased significantly after treatment (P < 0.01), but no difference in Mg group. (4) the decrement of blood pressure on PIH groups, compared with Mg group, was significant in Ng group and Combination groups (P < 0.05). CONCLUSIONS: Ng can reduce blood pressure, fetal-placenta circulation resistance, and inhibit PAg. It probably play a role on intrauterine growth retardation (IUGR) caused by PIH.

Adult↗

PubMed2001

Eye irritation caused by formaldehyde as an indoor air pollution--a controlled human exposure experiment.

OBJECTIVE: The present study focuses on health assessment of wood based panels which are widely used in interior decoration practices over the recent years in China. Formaldehyde has been identified as chemical indicator of (IAO) and an indoor air pollutant. To test its health effects experiment was undertaken. METHOD: A small environmental test chamber (60/L) was used as the generator of emission gas from new panels, and was operating at a temperature of 22.7 +/- 0.6 degrees C and a humidity of 44.4 +/- 2.5% with an air exchange rate of 1.0 +/- 0.15 h-1. On the three experimental days the values of product loading in chamber were 4, 2 and 6 m2/m3, respectively. Eight people were selected randomly from the students and employees of Wuhan Health and Anti-epidemic Station as subjects, with an average age of 21.9 +/- 5.9 years, and a gender ratio of 1:1, and two of them were smokers (one male and one female). The subjects' eyes were exposed to formaldehyde through a pair of goggles. Each goggle had its flow inlet and outlet, and connected to chamber exhaust of emission gas and to an exhaust from the room. The exposure time was very short, just 5 minutes and the formaldehyde doses were at 1.65 +/- 0.01, 2.99 +/- 0.07 and 4.31 +/- 0.02 ppm. A 60-mm linear visual analogue rating scales was used to measure the intensity of sensory eye irritation and a video tape recorder was used to record eye blinking frequency. RESULTS: The results demonstrated that tests of sensory eye irritation and eye blinking can be used for materials testing, and that a dose-effect as well as a time-variance of the effect can be measured. CONCLUSION: The tests showed that eye irritation was perceived at all of the three levels.

Adolescent↗

PubMed2001

[Expression of human leucocyte antigen in ectopic endometrial tissue of endometriosis].

OBJECTIVE: To investigate the human leucocyte antigen (HLA) expression of ectopic endometrial epithelial cells in cases with endometriosis and its role in pathogenesis of endometriosis. METHODS: By immunohistochemical analysis, HLA expression was observed in ectopic endometrial epithelial cells of 25 endometriosis patients. Ectopic endometrial cells were cultured in vitro successfully and the expression of HLA were analyzed by flow cytometry in 10 out of the 25 patients. Eutopic endometrium of 15 normal women were taken as control. RESULTS: (1) Expression of HLA class I molecule on ectopic endometrial epithelial cells of endometriosis measured by the immunohistochemical analysis was lower than those of controls, (4.0 +/- 0.5) score and (1.2 +/- 0.8) score respectively. So was the expression rate by flow cytometry in vitro culture (63.38 +/- 11.88)% and (5.27 +/- 2.88)% respectively (P < 0.01). (2) The expression of HLA class II molecule on ectopic endometrial epithelial cells of endometriosis was significantly increased. The outcome by immunohistochemical analysis was (0.2 +/- 0.1) score (control group) and (4.1 +/- 0.7) score (case group) and by flow cytometry was (7.19 +/- 2.43)% and (58.57 +/- 14.99)% respectively (P < 0.01). CONCLUSIONS: The abnormal HLA expression could play a role in the pathogenesis of endometriosis.

Adult↗

PubMed2001

[Immunological regulations of dendritic cell in abnormal scarring tissue].

OBJECTIVE: To investigate the relationship between dendritic cell(DC) and pathogenesis of abnormal scar. METHODS: The content of HLA-DR and CD1a molecules of DC, in 6 samples of hypertrophic scar (HS), keloid (K) and normal skin, were determined with the stain of avidin-biotin-peroxidase complex method (ABC). The effect of Triamcinolone Acetonide was evaluated with the measurement of the HLA-DR and CD1a molecules of DC in the epidermis of the HS. RESULTS: 1. The amounts of HLA-DR molecules of the positive DC were 806.67 +/- 101.72 and 870.00 +/- 134.24 in the HS and the K respectively, significantly higher than the controlled normal skin (510.01 +/- 45.17, P < 0.05). HLA-DR molecules showed an abnormal expression in the Kerationcytes and fibroblasts. 2. The amounts of CD1a molecules of the positive DC were 700.00 +/- 97.23 and 780.00 +/- 104.47 in the HS and the K respectively, significantly higher than the controlled normal skin (521.24 +/- 57.87)(P < 0.05). 3. The amounts of the HLA-DR molecules positive DC, in the positive kerationcytes and fibroblasts of hypertrophic scar, treated by Triamcinolone Acetonide, were 476.67 +/- 70.02 and 447.76 +/- 90.03 (P < 0.05) for 3 days and 7 days treatment respectively, significantly lower than the control. The amounts of CD1a molecules positive DC in the epidermis of hypertrophic scar with the injection of Triamcinolone Acetonide were significantly lower in 3 days and 7 days treatment (456.36 +/- 82.88 and 397.18 +/- 99.36, P < 0.05). CONCLUSION: 1. The results, with the high expression of HLA-DR and CD1a molecules, indicate that the HS and the K may have strong immune reactions. 2. Triamcinolone Acetonide may decrease the immune reactions of the HS, through the inhibition of the expressions of HLA-DR and CD1a molecules in the dendritric cell.

Cicatrix, Hypertrophic↗

PubMed2001

Diagnosis and treatment of bronchial rupture from blunt thoracic trauma.

OBJECTIVE: To evaluate the diagnosis and management of bronchial rutpture from blunt thoracic trauma. METHODS: A group of 31 patients with bronchial rupture was involved. Chest roentgenography, tomography and bronchoscopy were performed on all patients. The surgical technique and complications were described. RESULTS: Diagnosis was confirmed by tomography and bronchoscopy in all the patients. End to end anastomosis was used in 26 patients. Four patients were operated with total pneumonectomy. One patient was repaired with an intercostal muscle and rib flap with blood supply. Of the 31 patients, one died of adult respiratory distress syndrome after operation. Most patients had excellent surgical outcomes. 81% (25/31) of the bronchial rupture were delayed in diagnosis and treatment. The classic symptoms and signs of bronchial rupture included subcutaneous emphysema, dyspnea and an intermediate coma interval. The roentgenogram showed mediastinal emphysema, pneumothorax, "drop lung" sign and marked radiodensity of hilum widened mediastinum. CONCLUSION: Bronchoscopy is a useful and accurate method to diagnose and treat the bronchial rupture, with which surgeons can easily locate the rupture site during surgery. Surgical treatment could restore pulmonary function in most patients.

Adolescent↗

PubMed2001

[Relationship between follicular development and insulin like growth factor I receptor in stimulated cycles].

OBJECTIVE: To investigate the number of follicles and insulin-like growth factor I receptor (IGF-I R) in stimulated cycles. METHOD: IGF-I R mRNA and IGF-I R in granulosa cells obtained during oocyte retrieval were respectively measured by reverse transcript polymerase chain reaction (RT-PCR) and Western blot technique. RESULTS: The expression of IGF-I R mRNA in poor responders (follicles < or = 3) was much lower than in normal responders (follicles 4-13) and high responders (follicles > or = 14) (1.70 +/- 0.23, 2.92 +/- 0.49, 4.22 +/- 1.50 respectively). Similar results were obtained for IGF-I R (1.32 +/- 0.31, 2.01 +/- 0.72, 4.39 +/- 2.31 respectively). CONCLUSION: The expression of IGF-I R correlated with the effects of gonadotropin hormone on follicular development.

Adult↗

PubMed2001

[Pre- and post-contrast multiphase helical CT in the diagnosis of hepatic focal nodular hyperplasia].

OBJECTIVE: To analyse the pre- and post-contrast CT findings of liver focal nodular hyperplasia (FNH), so as to improve its diagnostic accuracy. METHODS: Pre-contrast scan and post-contrast tri-phase scan (arterial phase, portal venous phase and delayed phase) were performed in 21 patients with FNH which were proved surgically and pathologically. Transcatheter arterial angiography was performed in 2 patients. RESULTS: On pre-contrast scans, 16 of 21 lesions were hypodense, 5 of 21 were isodense. Twelve of 21 lesions showed punctate, streak and radial scar. On the arterial phase scans, all the lesions were markedly and homogeneously enhanced, except for the central scar. Nine of 21 lesions showed dilated and tortuous arteries at the central or peripheral area. On the portal venous phase scans, focal density was decreased, but still showing hyperdense or slightly hyperdense relative to the normal liver. On the delay phase scans, the lesions changed to isodense or slightly hypodense. Enhanced capsule was observed in 3 patients. On the angiography images, dilated arteries and drainage veins were seen. CONCLUSION: FNH has its special characteristics on the multiphasic helical CT scan. It is of great value in diagnosing the FNH and in choosing the appropriate therapy.

Adolescent↗

PubMed2001

[Relation between transcatheter arterial chemoembolization and time of death in patients with hepatic carcinoma].

OBJECTIVE: To evaluate the relationship between transcatheter arterial chemoembolization (TACE) and time of death in hepatic carcinoma patients. METHODS: One hundred and ninety-five patients (male 188, female 7) with liver cancer underwent TACE with patients dying at different intervals after treatment. Dose of antitumor drugs, amount of iodized oil, liver function, size, recurrence of surgical resection, pattern of tumor, metastasis, presence of portal vein thrombosis, post TACE relapse, post TACE liver function and AFP, etc, altogether 15 variables were subjected to statistical analysis with the Cox's hazard proportional model. RESULTS: According to univariate and forward stepwise regression analysis, factors associated with significantly worse survival were diffused type, multi-nodular growth of tumor, and tumor embolus in the portal vein (P < 0.0001). Before death, most patients had symptoms of chest oppression, shortness of breath, ascites, abdominal distension, jaundice, hepatic failure and hematemesis. Causes of death were hepatic coma (27.2%, n = 53), hepatic failure (23.1%, n = 45), hemorrhage from the digestive tract (36.9%, n = 72), multiple organ failure (5.1%, n = 10) and others (7.2%, n = 14). CONCLUSION: Several factors of TACE may lead to failure in liver function and death. TACE may hasten death in patients with severe liver functional embarrassment. Before instituting TACE, careful weighing the pros and cons of the general condition and liver function is important for patients with portal vein embolism, multiple tumors or diffused lesions. Tolerance of liver to the drug, time, dose and method of treatment should be meticulously and carefully planned. Post TACE protection of liver is also very important.

Adolescent↗

PubMed2001

[Clinical comparison between intraoperative local arterial infusion chemotherapy and systemic venous chemotherapy of gastric cancer].

OBJECTIVE: To evaluate the effect of intraoperative local arterial infusion chemotherapy for gastric cancer. METHODS: The effects of intraoperative local arterial infusion chemotherapy in 40 patients with gastric cancer were assessed. Twenty-four patients with gastric cancers who underwent the intraoperative systemic chemotherapy were taken as controls. The removed specimens were examined microscopically to show the degeneration and necrosis of the tumour cell. RESULTS: After the treatment of the tumour cells, all of the cases in the study group showed various degrees of degeneration and necrosis. The immediate effective rate was 95% for the the study group but only 41.67% for the control group (P < 0.05). CONCLUSION: Intraoperative local arterial infusion chemotherapy for gastric cancer has good immediate effect and little side effect; it prevents the intraoperative iatrogenic metastases and implantation and decreases the postoperative recurrence of gastric cancer.

Adenocarcinoma↗

PubMed2001

Epidermal growth factor prevents increased permeability and bacterial translocation in rats with acute pancreatitis.

OBJECTIVE: To evaluate the effects of epidermal growth factor (EGF) on intestinal permeability and bacterial translocation in rats with acute pancreatitis during total parenteral nutrition (TPN). METHODS: Thirty-two male Sprague-Dawley rats that underwent injection of 3.5% sodium taurocholate solution into the pancreatic duct were randomly divided into one of the following two groups: (1) received only TPN (control group) or (2) received TPN with EGF at a dose of 0.2 mg x kg(-1) x day(-1) (Egf group). On fifth day of total parenteral nutrition, samples from mesenteric lymph nodes, pancreas, liver and spleen were harvested for cultures. Water, protein and DNA content in jejunal mucosa were determined. D-xylose and fluorescein isothiocyanate (FTC)-dextran were instilled into the lumen of a ligated segament of small intestine. Thirty minutes later, superior mesenteric vein D-xylose and plasma FITC-dextran concentration were measured. RESULTS: Positive cultures in liver and spleen, as well as FITC-dextran concentration in the Egf group were significantly lower than in the control group. Protein and DNA content in jejunal mucosa in the Egf group were significantly higher than in the control group. CONCLUSION: The results indicate that EGF may prevent increased intestinal permeability and bacterial translocation in rats with acute pancreatitis during TPN.

Acute Disease↗

PubMed2001

[An association analysis of apolipoprotein E genotypes with Alzheimer's disease in Chinese population].

OBJECTIVE: To analyse the association of apolipoprotein E genotypes with Alzheimer's disease in Chinese population. METHODS: Using PCR and restriction enzyme digestion, we have analyzed ApoE allele frequency of Alzheimer's disease (AD) patients and healthy controls. RESULTS: Among the 56 cases of AD, the frequency of ApoE epsilon 2, ApoE epsilon 3, ApoE epsilon 4 are 3 (2.7%), 84 (75.0%), 25 (22.3%) respectively, while in the 67 controls they are 9 (6.7%), 115 (85.8%), 10 (7.5%) respectively. The frequencies of the two groups have significant difference (P < 0.01) and the frequency of ApoE epsilon 4 allele is higher in AD than that in the health controls and the statistical treatment suggest that there is significant difference (chi 2 = 10.99, P < 0.01, OR = 3.59, 95% CI = 1.54-8.41). The frequency of the ApoE epsilon 3 is lower in AD than that in the health controls and the difference is also statistically significant(P < 0.05). CONCLUSIONS: Our results are consistent with previous work in that proving the ApoE epsilon 4 allele is one of the risk factors of AD. The results also provide a support for the protection effect of ApoE epsilon 3 allele in developing AD.

Aged↗

PubMed2001

[Analysis of the lineshape of laser frequency modulation].

In this paper, we analyze the dependence of the output signal spectral lineshape and intensity on the modulation, waveform and modulation index in first- and second-harmonic detection of triangle modulation, square demodulation and saw modulation square demodulation. The signal lineshape in the case of saw modulation, square demodulation is quite different from, whereas the signal lineshape in the case of triangle modulation, square demodulation is similar to that in traditional sine modulation, sine demodulation. Experiments of tunable IR laser frequency modulation absorption spectrum of methane are also done to verify the theoretical analysis. Then we reach a conclusion; the lineshape and intensity of frequency modulation spectrum can be influenced by modulation waveform, demodulation waveform and modulation index. Calculation results can be used to choose better experimental parameters and optimize experimental designs.

Algorithms↗

PubMed2001

[Monte Carlo simulation of FCS in a laser gradient field].

Fluorescence correlation spectroscopy (FCS) is a powerful tool for probing biological process inside living cells. It measures fluorescence fluctuations of small number of molecules and derive information on molecular kinetics and reactions. We have developed a Monte Carlo model to simulate Browning motion of Rayleigh particles in a laser gradient field. The simulation reveals relations between laser field strength and measured parameters from FCS, such as diffusion coefficient and number density of the particles. The simulated results agree qualitatively to the experimental results obtained using fluorescent spheres. Empirical relations from the simulation are also discussed.

Computer Simulation↗