Biomedical subjects

Hui Chen

Publications and source records attributed to Hui Chen.

At least 199 records · Page 11Linked to original sources

PubMed2002

Dynamics of 95Zr in the rice/water/soil system.

In order to get a better understanding of the environmental behavior of 95Zr and to generate fundamental data for evaluation of its ecological risk, an experiment was conducted to study 95Zr dynamics in a simulated rice/water/soil system. The results showed that the concentration of 95Zr in surface water decreased rapidly with time due to precipitation, adsorption to soil and uptake by rice, and most of 95Zr in soil was found concentrated in the surface layer (0-8 cm from surface). The 95Zr could not readily move downwards with percolating water and remained in surface soil. The 95Zr taken up from surface water and surface soil mainly concentrated in roots and lower parts of stem. The concentration of 95Zr in upper part of stem and leaves were relatively lower, which were only slightly greater than the detection limit. The 95Zr concentration in tassel was near the detection limit. The dynamics of 95Zr concentrations in rice, water and soil can be described with exponential function.

Environmental Monitoring↗

PubMed2002

Deficiency of KIT-positive cells in the colon of patients with diabetes mellitus.

BACKGROUND: Diabetes mellitus is a well-known cause of gastrointestinal dysmotility. The pathogenesis of diabetic gastroenteropathy is mainly considered to be a neuropathy, but the cause of dysmotility remains unknown. Interstitial cells of Cajal (ICC), which express c-kit receptor tyrosine kinase (KIT), are considered to be pacemaker cells for the gastrointestinal movement. Therefore, we investigated a possible involvement of ICC in the pathogenesis of diabetic gastroenteropathy in humans. METHODS: The KIT-positive cells in the proper muscle layer of the colon were detected by immunohistochemistry in patients with diabetes mellitus and normal control subjects. Mast cells, which are also known to express KIT, were detected by staining with Alcian blue. The numbers of KIT-positive cells and Alcian blue-positive cells in the proper muscle layer were counted under the microscope and the number of KIT-positive cells apart from Alcian blue-positive cells was calculated. RESULTS: In the normal control subjects, KIT-positive cells were located at the myenteric plexus region and in the circular muscle layer of the colon. Their distribution pattern was similar to that of ICC. The average number of KIT-positive cells, apart from mast cells (which reflects the number of ICC), in patients with diabetes mellitus was approximately 40% of that found in normal subjects. CONCLUSIONS: Deficiency of ICC might be related to the pathogenesis of diabetic gastroenteropathy in humans.

Adult↗

PubMed2002

Familial gastrointestinal stromal tumors associated with dysphagia and novel type germline mutation of KIT gene.

A family with multiple gastrointestinal stromal tumors (GISTs), a new type of germline mutation of KIT gene, and dysphagia is reported. The mutation was observed at Asp-820 in tyrosine kinase (TK) II domain. Mutations in TK II domain have been found in mast cell and germ cell tumors but not in GISTs, and the present family members are the first reported cases of GISTs with TK II domain mutations, including sporadic GISTs. Because interleukin 3-dependent Ba/F3 murine lymphoid cells transfected with the mutant KIT complementary DNA grew autonomously without any growth factors and formed tumors in nude mice, the mutation was considered to be gain-of-function type. Family members with the germline KIT mutation reported dysphagia, but those without the mutation did not. The mechanism of dysphagia was examined with gastrointestinal fiberscopy, endoscopic ultrasonography, and esophageal manometry. No mechanical obstruction was found, and the esophagus was not remarkably dilated. In the family members with dysphagia, endoscopic ultrasonography at the esophagocardiac junction showed a thickened hyperechoic layer between the circular and longitudinal muscle layers, suggesting hyperplasia of interstitial cells of Cajal at the myenteric plexus layer. Manometry showed low resting lower esophageal sphincter pressure and abnormal simultaneous contractions of the esophagus without normal peristalsis. These findings indicate that the dysphagia of the present family is different from typical achalasia. This is the first report of familial dysphagia caused by germline gain-of-function mutation of the KIT gene at the TK II domain.

Aged↗

PubMed2002

Long-term outcome and quality of life after the Swenson procedure for Hirschsprung's disease.

BACKGROUND/PURPOSE: The aim of this study was to investigate long-term outcome and quality of life after the Swenson operation for rectosigmoid Hirschsprung's Disease (HD). METHODS: Forty-five patients who underwent the Swenson procedure for HD underwent follow-up for 8 to 16 years. Long-term outcome and quality of life were assessed by interviews and questionnaires including scoring systems. Forty-four healthy children with similar age, sex, and education level distributions used as controls. RESULTS: In 45 patients, 23 (51.1%) had bowel dysfunction. Seventeen patients (37.8%) suffered from fecal soiling. According to the clinical bowel function scoring system, the patients' scores (7.6 +/- 2.1) were significantly lower than those of the controls (11.4 +/- 0.6; P <.05). Because of poor fecal continence, 25 patients (55.7%) had to restrict their foods. School absence occurred in 6 (13.3%) patients. Seven patients (15.6%) had problems in peer relationships. According to the Quality-of-Life Scoring Criteria, 86.7% patients had good or fair quality of life. The patients' scores (7.7 +/- 2.9) were significantly lower than those of the controls (11.6 +/- 0.7; P <.05). And the scores of patients who had fecal soiling and incontinence (6.3 +/- 2.7) were significantly lower than those of patients without fecal soiling and incontinence (8.4 +/- 2.6; P <.05). CONCLUSIONS: Although most patients had good or fair quality of life after surgical correction for HD, the long-term outcome and quality of life are not as good as surgeons expected. The bowel function and quality of life of the patients were poorer than those of healthy children. Fecal soiling is very common and affects patients' quality of life. Long-term regular follow-up is indispensable. Close attention should be paid to minimizing bowel dysfunction for patients with HD postoperatively to improve their quality of life.

Adolescent↗

PubMed2002

Optimization of single-phase, unidirectional transducers using three fingers per period.

Electrode width controlled (EWC) single-phase, unidirectional transducers (SPUDT) is widely used for low loss surface acoustic wave (SAW) filters. The insertion loss and fractional bandwidth of the filters are strongly related to the reflectivity of EWC cells. In order to achieve wide band and low loss simultaneously, it is necessary to obtain higher reflectivity. The relationship between geometrical configuration of EWC cells and reflection coefficient, (and transduction coefficient as well) is studied. Simulation results indicate that the reflectivity of the EWC SPUDT cell could exceed 5% on a 128 degrees Y-X lithium niobate (LiNbO3) substrate. Using such structure, low loss SPUDT test filters without weighting are fabricated. The measured 3 dB bandwidth is 3.9% and the insertion loss is 2.9 dB. The theoretical calculation is verified by the experiment.

Acoustics↗

PubMed2002

Fast, precise, and full extraction of the COM parameters for multielectrode-type gratings by periodic Green's function method.

It is very important to extract all four coupling-of-modes (COM) parameters of the electrode cells for the simulation and optimal design of a low loss surface acoustic wave (SAW) filter. A new approach for fast and full extraction of the COM parameters for multielectrode-type grating is proposed. The field distribution of the wave under the periodic shorted grating is calculated by periodic Green's function method. The phase of the reflection is determined from the positions of the standing wave node. The transduction coefficient and its phase are determined by the charge distribution at low frequency. The COM parameters of the commonly used electrode width controlled (EWC) single phase unidirectional transducer (SPUDT) is computed. It shows that this is a simple and direct way to extract all the COM parameters for SPUDT and, accordingly, is a powerful tool for the optimization of the filter structure.

Acoustics↗

PubMed2002

Smad3 deficiency attenuates bleomycin-induced pulmonary fibrosis in mice.

Transforming growth factor-beta (TGF-beta) signaling plays an important regulatory role during lung fibrogenesis. Smad3 was identified in the pathway for transducing TGF-beta signals from the cell membrane to the nucleus. Using mice without Smad3 gene expression, we investigated whether Smad3 could regulate bleomycin-induced pulmonary fibrosis in vivo. Mice deficient in Smad3 demonstrated suppressed type I procollagen mRNA expression and reduced hydroxyproline content in the lungs compared with wild-type mice treated with bleomycin. Furthermore, loss of Smad3 greatly attenuated morphological fibrotic responses to bleomycin in the mouse lungs, suggesting that Smad3 is implicated in the pathogenesis of pulmonary fibrosis. These results show that Smad3 contributes to bleomycin-induced lung injury and that Smad3 may serve as a novel target for potential therapeutic treatment of lung fibrosis.

Animals↗

PubMed2002

Insulin receptor substrate-1 and phosphoinositide-dependent kinase-1 are required for insulin-stimulated production of nitric oxide in endothelial cells.

Vasodilator actions of insulin are mediated by signaling pathways involving phosphatidylinositol 3-kinase (PI 3-kinase) and Akt that lead to activation of endothelial nitric oxide synthase (eNOS) in endothelium. Signaling molecules immediately upstream and downstream from PI 3-kinase involved with production of NO in response to insulin have not been previously identified. In this study, we evaluated roles of insulin receptor substrate 1 (IRS-1) and phosphoinositide-dependent kinase 1 (PDK-1) in production of NO. The fluorescent dye 4,5-diamine fluorescein diacetate was used to directly measure NO in NIH-3T3(IR) cells transiently cotransfected with eNOS and various IRS-1 or PDK-1 constructs. In control cells, transfected with only eNOS, insulin stimulated a rapid dose-dependent increase in NO. Overexpression of wild-type IRS-1 increased the maximal insulin response 3-fold. Overexpression of IRS1-F6 (mutant that does not bind PI 3-kinase) or an antisense ribozyme against IRS-1 substantially inhibited insulin-stimulated production of NO. Likewise, overexpression of wild-type PDK-1 enhanced insulin-stimulated production of NO, whereas a kinase-inactive mutant PDK-1 inhibited this action of insulin. Qualitatively similar results were observed in vascular endothelial cells. Production of NO by a calcium-dependent mechanism in response to lysophosphatidic acid was unaffected by either wild-type or mutant IRS-1 and PDK-1. We conclude that IRS-1 and PDK-1 play necessary roles in insulin-signaling pathways leading to activation of eNOS. Furthermore, classical Ca2+-mediated pathways for activation of eNOS are separable from IRS-1- and PDK-1-dependent insulin-signaling pathways.

3-Phosphoinositide-Dependent Protein Kinases↗

PubMed2002

[Influence of different DNA extractions on the identification of streptococcus sanguis group by arbitrary primed polymerase chain reaction]

OBJECTIVE: To assess the influence of different DNA extractions on the identification of streptococcus sanguis group (SSG) species by arbitrary primed polymerase chain reaction (AP-PCR). METHODS: AP-PCR was used to distinguish SSG species by designing 25bp arbitrary primer 5'AAG AGA GGA GCT AGC TCT TCT TGG A 3', and the genomic DNA was extracted by 3 methods. RESULTS: There were great differences in the main band of DNA polymorphism among SSG species. The similar band could be got from the different DNA extractions in the same species. CONCLUSION: Different DNA extractions have no influence on the identification of SSG.

Journal Article↗

PubMed2002

[Basis of art phonetics in biomedical engineering].

Art phonetics' medicine, a new branch of traditional medicine, has not been developed perfectly, especially in the aspects of objective and scientific study. In this paper, the acoustical and anatiomical basis of art phonetics in viewpoint of biomedical engineering is explored, and then our work of quantitative measurement and analysis of art phonetic is introduced. The experiment data show further that quantitative measurement and analysis plays an important role in art phonetic medicine.

Acoustics↗

PubMed2002

[Levels and clinical significance of CD44 (intron 9) and CD44v6 in malignant cerebroma].

OBJECTIVE: To investigate the expression of CD44 (intron 9) and CD44v6 in brain neoplasm. METHODS: CD44 (intron 9) and CD44v6 were detected in malignant meningoma, encephalic glioma, and normal encephalic tissues around the brain noeplasm respectively by using RT-PCR. RESULTS: The positive expression rate of CD44v6 was 92.86% (26/28) in malignant meningoma and 88.0% (22/25) in encephalic glioma. They were significantly higher than 5.0% (1/20) in normal encephalic tissues (P < 0.01). Mass values of malignant meningoma and encephalic glioma were higher than that of normal encephalic tissues (P < 0.01). The expression of CD44 (intron 9) was higher in malignant meningoma and encephalic glioma than in normal encephalic tissues (P < 0.01). CONCLUSIONS: Detection of CD44 (intron 9) and CD44v6 might be helpful to the diagnosis of malignant cerebroma.

Adolescent↗

PubMed2002

[Dynamics of accumulation and disappearance of Zirconium-95 in the maize/soil and soybean/soil ecosystem].

The dynamics of accumulation and disappearance of 95Zr in two kinds crop-soil ecosystem was studied by using isotope-tracer techniques for simulated pollutants, and the fitting equation was confirmed by application of the closed tow-compartment model and nonlinear regression method. The results showed: 1. The Zirconium-95 absorbed from soil main retention in root of the maize and soybean, and the specific activity of 95Zr in root increased with time slowly, then tended dynamics balance gradually after a period of time. The specific activity of rest parts was lower, and biggish parts were background activity level, which indicated that the 95Zr absorbed by roots was difficult of transference and transportation in the maize and soybean. 2. The 95Zr in soil main retention in surface layer soil(0-8 cm), and the rate of it's activity and total activity > 97.5%, which indicated that the 95Zr absorbed by surface soil could not readily move downwards with percolating water. 3. The regression equation of accumulation and disappearance of 95Zr in the maize and soybean were Cm(t) = 3.2067(1 - e-0.1582t) and Cb(t) = 3.0925(1- e -0.1363t) by analyzing the experiment data with exponential regression method. The results of squared deviations analyzing indicated that each regression equation could describe the dynamics of accumulation and disappearance of 95Zr in the maize-soil and soybean-soil ecosystems preferably.

Ecosystem↗

PubMed2002

[Dynamic characteristics of nutrient elements in Castanea henryi plantation at beginning of fructification and its simulation].

The dynamic variation of nutrient elements in Castanea henryi plantation was analysed and simulated by means of a system analysis, and the models of four compartments including aboveground, root, soil and litter were constructed. Evaluation on the nutrient pools of N, P, K, Ca and Mg in the four compartments at the beginning of fructification showed that soil compartment had highest content of N, P, K and Ca which was up to 311.47, 11.64, 218.90 and 87.56 kg.hm-2, respectively. The highest Mg occurred in litter compartment, up to 7.563 kg.hm-2. Based on the compartment model, the fluxes and rates of the five nutrient elements between the compartments were calculated, and their changing trends in compartments in 5 years were forecasted. The results showed that the most suitable amount of annually compensating the five elements was 20(N), 8(P), 5(K), 10 (Ca) and 5 (Mg) kg.hm-2, respectively. This nutrient compensation promoted the nutrient flows, and normalised the growth and metabolism of the tree. The research could provide with important basic data for nutrient management of this type of plantation at this stage.

Calcium↗

PubMed2002

Reversed flow injection spectrophotometric determination of low residuals of chlorine dioxide in water using chlorophenol red.

A novel, simple, rapid, sensitive and highly selective flow injection procedure for the spectrophotometric determination of chlorine dioxide in the presence of other chlorine species, viz, free chlorine, chlorite, chlorate and hypochlorite, is developed. The method is based on the discoloration reaction between chlorine dioxide and chlorophenol red and can overcome the shortcomings existed in direct spectrophotometric determination for chlorine dioxide owing to the serious interference of free and combined chlorine. The procedure gave a linear calibration graph over the range 0-0.71 mg/L of chlorine dioxide. With a detection limit of 0.024 mg/L and a sample throughput of 60 samples/h.

Chlorine Compounds↗

PubMed2002

[Effect of covering with new soil on reducing the accumulation of radio-strontium in plant].

Effects of covering with new soil on reducing the accumulation of 89Sr by soybean and Chinese cabbage (especially in the edible part of crop) were studied on simulated pollutants by using the isotope-tracer techniques. The results showed that the absorption and accumulation of 89Sr in the soybean and Chinese cabbage could be decreased significantly by covering soil polluted 89Sr with new soil. The specific activity of 89Sr in bean hull, bean straw, bean root and Chinese cabbage were reduced by 82.8%, 56.4%, 38.7%, 66.5% and 68.8% respectively when the depth of covering with new soil reached 9 cm. The specific activity of absorption and accumulation 89Sr in the crop decreased with depth of the new soil profile. The specific activity of 89Sr in the crop follows a negative linear relation with depth of the new soil profile by analyzing the experiment data with linear regression method.

Plants↗

PubMed2002

The relativity between Streptococcus sanguis group and coronary heart disease.

OBJECTIVE: To study the relativity between Streptococcus sanguis group (SSG) and coronary heart disease (CHD). METHODS: 41 individuals were diagnosed with CHD and 18 normals served as controls. All of them had undergone coronary angiography. Their social class (including education and wages), smoking, drinking, blood lipids and oral health were also recorded. SSG in saliva and subgingival plaque were cultivated in NAYS-B agar plates and counted. SSG were identified into species with routine biochemical reaction and AP-PCR. RESULTS: In the multiple step regression analysis, the amount of SSG in saliva and subgingival plaque were positively associated with severe coronary atheromatosis after adjusting the classical risk factors of CHD. The average amount of SSG in saliva was (435 +/- 422) x 10(8) CFU/L in CHD group and (358 +/- 540) x 10(8) CFU/L in control group, F = 2.72, P = 0.08; the average amount of SSG in incisor was (331 +/- 484) x 10(7) CFU/L in CHD group and (98 +/- 164) x 10(7) CFU/L in control group, F = 5.54, P = 0.02; the average amount of SSG in molar was (352 +/- 381) x 10(7) CFU/L in CHD group and (185 +/- 232) x 10(7) CFU/L in control group, F = 2.86, P = 0.10. S. sanguis and S. gordonii were more in CHD group than in control group (P < 0.05), whereas S. mitis and S. oralis were the same in two groups (P > 0.05). CONCLUSION: The increase of SSG in oral floras may play an important role in the occurrence of CHD.

Aged↗

PubMed2002

[Studies on enzymatic synthesis of cephalexin by immobilized penicillin acylase by polyacrylonitrile fibres].

The extracellular penicillin acylase from Bacillus megaterium was immobilized by coupling to derivatives of polyacrylonitrile fibres. The apparent activity of the immobilized enzyme was about 153 U/g (wet weight). The optimal pH and temperature were 6.5 and 40 degrees C for synthesis of cephalexin by penicillin acylase, respectively. Whe the concentration of 7-ADCA was 4% and the ratio of PGME and 7-ADCA and 1:2, the average velocity of synthesis reaction was highest. The optimal supplied amount of immobilized penicillin acylase was 1.125 g/g 7-ADCA.. The apparent Michaelis constant for 7-ADCA was 0.162 mol/L and for PGME was 0.364 mol/L, Vmax was 0.0462 mol.L-1.min-1 at 30 degrees C and pH6.5. The remained activity was about 83.9% after operating 50 times.

Acrylic Resins↗

PubMed2002

[Chop technique with lens loop-pad and foldable intraocular lens implantation].

OBJECTIVE: To evaluate the use of chop technique with lens loop-pad and foldable intraocular lens implantation for cataract surgery. METHOD: Chop technique with self-designed lens loop-pad and foldable intraocular lens implantation were performed on 73 eyes of 64 cases with senile cataract. RESULTS: The intraoperative complication was posterior capsular rupture in only 2 cases. All the patients had very mild postoperative reaction and round pupil. The corrected visual acuity was improved to 0.5 or over in 79.5% (58 eyes) at one week postoperatively, and in 89.0% (65 eyes) at three months postoperatively. The mean percentage of endothelial cell loss was 14.1% (t = 17.46, P < 0.001) at the superior area of cornea and 12.2% (t = 17.52, P < 0.001) at the center of cornea. CONCLUSION: It is suggested that the chop technique with lens loop-pad simplify the procedure, and be safer and more reliable, achieving the goals of small incision cataract surgery.

Aged↗