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Biomedical subjects

M Chen

Publications and source records attributed to M Chen.

At least 181 records · Page 10Linked to original sources
PubMed2001

[The value of number connection test in the diagnosis of subclinical hepatic encephalopathy].

OBJECTIVE: To explore the influencing factors and diagnostic values of number connection test (NCT) in detection of subclinical hepatic encephalopathy (SHE). METHODS: NCT was carried out in four hundred and fifty healthy volunteers to explore the influencing factors and to work out a reference value. Then forty patients with liver cirrhosis were studied with NCT, intelligence quotient (IQ) and evoked potentials(EP) to determine the value of NCT in the diagnosis of SHE. RESULTS: (1) NCT results were influenced by age and educational background. The older the age and the lower the educational level, the longer the NCT time (P < 0.001); (2) The abnormal rate of NCT was 30% (12/40), being lower than the IQ abnormal rate of 58% (23/40) (P < 0.01). (3) IQ or/and EP were abnormal in 85%. (4) The combination of four tests i.e. block design, picture arrangement, object assembly and NCT were abnormal in 53% of the patients. Comparing with the abnormal rate (58%) of full set of IQ test, the sensitivity and specificity were 87% and 94%, respectively. CONCLUSIONS: NCT result was influenced by age and educational background and the sensitivity was low for the scanning of SHE. Combination of four psychometric tests: block design test, picture arrangement, object assembly and NCT was recommended to substitute full set of IQ test in the diagnosis of SHE.

Adult↗
PubMed2001

[Estimation of insulin secretion rate in multiple sampled intravenous glucose tolerance test].

OBJECTIVE: To measure and calculate insulin secretion rate(ISR) in multiple sampled intravenous glucose tolerance test (FSIVGTT) according to the two compartment model and standard parameters of the kinetics of connecting peptide (C-P) in vivo. METHODS: 15 subjects with normal glucose tolerance and 11 type 2 diabetic patients took part in the study. Oral glucose tolerance test (OGTT) and FSIVGTT were performed. Glucose concentrations were measured by hexokinase method. Insulin (INS) and C-P concentrations were measured by radioimmunoassay. A computer procedure devised by our laboratory was used to calculate the value of ISR at each time point. RESULTS: In the control group, serum INS and C-P concentrations reached the peak at 4 min, the second peak was not obvious. In type 2 diabetes, only 5 subjects had a small peak within 4 min, two curves reached its peak between 60 and 80 min. In the control group, ISR reached its peak 2 min after injection of glucose, that was earlier than INS and C-P curves in time sequence (P = 0.000), the second obvious peak was shown at 22 min. In type 2 diabetes, an obvious but small peak of ISR was shown at 2 min and all the patients had this peak. CONCLUSIONS: It is necessary to take the process of metabolic clearance of INS and C-P into consideration, when blood concentration of INS and C-P were used as indexes to evaluate the secretion function of beta-cells. The ISR profile is more sensitive for investigation of the second phase of insulin secretion in the control group and the first phase in type 2 diabetes group.

Blood Glucose↗
PubMed2001

[Response of lithium fluoride detector to charged particle LET].

Response of LiF thermoluminescence (TL) detector to charged particle is dependent on particles' LET. High LET can cause reduction of detector response and underestimation of radiation dose. This paper summarized the response of LiF detector to charged particles' LET, and suggested a new approach to solve the dose contribution of high LET charged particles.

Extraterrestrial Environment↗
PubMed2001

[Effects of soil water condition and microclimate on transpiration rate of rice].

The transpiration rate and water use efficiency (WUE) of rice were studied under high, moderate and low soil water conditions (treatments A, B and C) in the red soil area of southern China. Diurnal variation of transpiration showed that rice transpiration rate was influenced by several microclimatic factors in the field. Correlation analysis and stepping multi-regression analysis suggested that the difference of relative humidity between leaf and air, and the leaf temperature were the two main factors affecting the transpiration rate of rice. The results also showed that WUE was and yield were increased significantly in treatment B. While in treatment C, the WUE increased, but the yield of late rice decreased. The transpiration rate of early rice was decreased under moderate and low soil water treatments, but this did not happen to late rice.

Ecosystem↗
PubMed2001

[Pathogen detection in the myocardial lesion using in situ RT-PCR in mice induced by experimental CoxB(3m) virus infection].

OBJECTIVE: To detect the location of pathogens in myocardium using in situ RT-PCR technique in order to study the pathogenetic course of the myocardial lesion induced by CoxB(3m) virus infection in mice. METHODS: (1) Thirty and fifty Balb/c mice were used respectively to establish the acute and chronic CoxB(3m) infected models, with another 25 healthy mice as the controls; (2) KS400 image analysis system (Germany) was used to measure the cardiac chamber area and the left ventricular wall thickness of the chronic infected mice and the controls; (3) CoxB(3m) virus in myocardial tissue was detected using in situ RT-PCR by direct incorporated technique which employed nucleotide labeling by anti-digoxin antibody and bonded with alkaline phosphatase (anti-dig-AKP method). RESULTS: Picture analysis indicated that the left ventricular chamber area was enlarged and the left ventricular wall was thinner in the chronic repeated virus infected models than those of the controls. With in situ RT-PCR, positive signals for Coxsackie virus B(3m) RNA were detected not only in the myocardium of the acute Balb/c mice models but also in the myocardium of the chronic mice models. CONCLUSION: Coxsackie virus B(3m) is able to induce pathologic lesions by exhibiting positive CVB-RNA signals in both acute and chronic models in mice. In the chronic experimental models, the cardiac chamber is enlarged while the ventricular wall is thinned which demonstrates the association with persistent infection of Coxsackie virus B(3m) virus.

Animals↗
PubMed2001

[The effects of sodium butyrate on proliferation, differentiation and apoptosis in immortalized esophageal epithelial cells].

OBJECTIVE: To study the effects of sodium butyrate on proliferation, differentiation and apoptosis of immortalized esophagus epithelial cells. METHODS: SHEE, an immortalized human fetal esophageal epithelial cell line induced by HPV18 E6E7, was cultivated in culture flasks and 24-well plates. Two experiment groups of cultured cells were treated with 1 and 5 mmol/L of sodium butyrate respectively for 4 days, and one group of untreated cells set aside as control. The numbers of cloned cells were calculated. The ultra-structure of SHEE cells was examined by transmission electron microscopy (TEM). The cell cycle and number of apoptotic cells were measured by flow cytometry, Ki-67 and cytokeratin of cells were detected by immunohistochemistry method and F-actin of cells labeled with phalloidin was examined by laser confocal scanning microscopy. RESULTS: Colony formations showed a significant decrease in the 2 experiment groups after 4 days of culture (P < 0.01). In the 1 mmol/L group, the cells at S phase were diminished and arrested at G(0)/G(1) phase. Compared with control group, Ki-67 positive cells were found decreased, while F-actin and cytokeratin were increased. Apoptotic cells in 5 mmol/L group were increased markedly. CONCLUSIONS: Sodium butyrate may induce SHEE cells growth arrest, differentiation and apoptosis. The effects depend on sodium butyrate concentration and time of exposure. Whether it can be used in combination with other anticancer drugs should be further studied.

Actins↗
PubMed2001

[Jīvaka's recipes in Indian ancient medical texts].

Jīvaka was very important in the history of Indian Buddhist medicine, and Indian āyurvedic classics yet ascribed some recipes to him. Jīvaka's four recipes from Nāvanītaka, Carkadatta, and Bodhisattva - garbhastha - sūtra etc. were handed down, reflecting his medical achievements.

Buddhism↗
PubMed2001

[Pharmacodynamics study of suanzaoren decoction extracted by different technological process].

OBJECTIVE: To select the optimal technological process for Suanzaoren decoction. METHOD: The effects of extracts from different technological processes on spontaneous motion and sleep time in mice induced by pentobarbital sodium (subthreshold dosage) were studied. RESULTS: Both the decoction and 95% alcohol extract of Suanzaoren possess sedative and hypnotic effects. CONCLUSION: Suanzaoren aqueous decoction was selected as the optimal technological process.

Animals↗
PubMed2001

Study on detecting antibodies to Toxoplasma gondii in pooled serum of blood donors by Dot-IGSS.

To prevent post-transfusion toxoplasmosis, the sera of blood donors, per six of which were mixed as a pool, were examined for anti-Toxoplasma gondii antibiodies by Dot-immunogold silver staining (Dot-IGSS) with the single serum specimens examined simultaneously. The results showed that the sensitivity and specificity of serum pool method were 92.31% and 99.96% respectively. The consistent rate between the two methods was 99.73% and kappa value was 0.947 (p<0.01). Considering the mean infection rate of Toxoplasma gondii being 4.86% in China, if the serum pool method be adoped, with pool size k=5, a 57% reduction in the number of tests, as well as the cost of the screen, can be expected. Beside the social benefit, consequent upon the interruption of the Toxoplasma gondii infection spread through blood transfusion also can be expected.

Animals↗
PubMed2001

[Purification of conjugated bilirubin from human urine].

OBJECTIVES: To develop a simple, practical method with fine yield and purity for separating conjugated bilirubin(Bc) from a sustainable and facile material in order that it could serve as a calibrator for total and direct bilirubin determination. METHODS: Isolating Bc from urine of patients with obstructive jaundice by CHCl3: CH3CH2OH(1:1, V/V) followed by CNBr activated Sepharose 4B-HAS affinity chromatography, we analyzed the products by the use of Doumas J-G diazo method and HPLC, respectively. RESULTS: Determined by J-G diazo method, the crude product extracted by CHCl3: CH3CH2OH(1:1, V/V) yields 90.2 +/- 5.4%(n = 3) of urine Bc, the ratio of Bc to total dry weight being 67.9 +/- 6.4%(n = 3). The final product purified by affinity chromatography with the ratio of separation of 1.5, 1.737 and analyzed by HPLC has the yield of 46.9% and purity of 94.7%(BDG of 76.2%, BMG of 18.5%). CONCLUSION: The above data demonstrate that urine conjugated bilirubin can be successfully purified by CHCl3: CH3CH2OH extraction followed by Sephrose-HSA affinity chromatography with sufficient purity and output.

Bilirubin↗
PubMed2001

[The detection of phenol degrading strain in environment with specific primer of phenol hydroxylase gene].

A 684 bp oligonucleotide fragment was produced by PCR amplification from phenol-degrading strain Acinetobacter calcoaceticus PHEA-2 with the specific primers of gene encoding phenol hydroxylase. The nucleotide sequence of this fragment and its deduced amino acid sequence share 84% and 98% homology with the phenol hydroxylase gene and its deduced amino acid sequences of phenol-degrading strain Acinetobacter calcoaceticus NCIB8250. Sets of different aromatic compounds degrading strains were used to test this specific prime. The 684 bp-fragments were amplified only from phenol-degrading strains by PCR. When using this pair of primers to detect the bacterial isolates from wastewater discharged from coking plant, all the tested strains, which possess 684 bp characteristic fragment, showed the ability to degrade phenol in this study.

Acinetobacter calcoaceticus↗
PubMed2001

[Isolation and characterization of a plasmid pTS50, which encodes nisin resistance determinant in Lactococcus lactis TS1640].

Three nisin-resistant Lactococcus lactis strains were screened from 197 samples of fresh milk on a selective medium (M17) supplemented with nisin, lactose and bromocresol purple, and were confirmed to have the nisin resistance determinant (nsr) by PCR amplification. Physiological and biochemical tests as well as Lactococcus lactis specific 16S rDNA sequence analysis revealed that the three strains all belong to Lactococcus lactis subsp. lactis. A large plasmid, pTS50, was identified in L. lactis subsp. lactis TS1640 which encodes resistance to nisin following electroporation of the total plasmids DNA into L. lactis MG1363. The molecular weight of plasmid pTS50 was estimated to be 47 kb by restriction analysis of BamHI, EcoRI, HindIII, NcoI, PstI and nsr was localized on a 1.9 kb EcoRI fragment by Southern hybridization.

Animals↗
PubMed2001

[Isolation and identification of the broad spectrum antimicrobial peptide AP311 produced by Lactobacillus acidophilus].

The heat stable antimicrobial peptide (AP311) produced by Lactobacillus acidophilus was isolated and identified. The AP311 has broad spectrum of inhibition including many Gram-positive and Gram-negative bacteria. The inhibition activity of AP311 was lost upon treatment with trypsin, subtilisin, proteanase K, chymotrypsin and pepsin. Inhibition activity of AP311 was decreased with pH increasing. The AP311 is very stable at acidic condition (pH2-4) even if heating at 100 degrees C for 30 min. But it was inactivated at basic pH (pH12) and the activity was restored completely upon reversion to acidic. The AP311 was not precipitated and inactivated by various organic solvents, except n-butanol. When the precipitate was redissolved in 0.02 mol/L HC1, its activity was restored. Based on its proteinaceous nature, broad spectrum of inhibition, we propose that AP311 should be considered the broad spectrum antimicrobial peptide.

Anti-Bacterial Agents↗
PubMed2001

[An abzyme to catalytize the deiodination of thyroxine].

AIM: To mimic an important family of selenoenzymes in organism-thyroxine (T4) deiodinases and prepare a selenium-containing abzyme catalyzing deiodination of T4. METHODS: A anti-T4 monoclonal antibody was generated by hybridoma methodology and converted into a selenium-containing abzyme by the method of chemical modification. The catalytic activity of the enzyme was measured by RIA method. RESULTS: The abzyme displayed a marked activity of catalyzing deiodination of T4 and a higher specificity to the substrate T4 than that of natural enzyme, and the double reciprocal plots of the initial rates of T3 formation vs. T4 concentration yielded a family of parallel lines. The catalytic activity could be sensitively inhibited by 6-propyl-2-thiouracil (PTU), a competitive inhibitor for dithiothreitol (DTT). CONCLUSION: An abzyme with the diodination activity was first prepared and the reaction mechanism of the enzyme was bisubstrate ping-pong one.

Animals↗
PubMed2001

[Isolation of a kind of endophytic fungus which can produce taxol compounds].

OBJECTIVE: To isolate a kind of endophytic fungus which can produce taxol compounds from the bark of Taxus Cuspidata Sieb et Zucc. METHODS: Endophytic fungus was isolated from the bark of Taxus Cuspidata Sieb et Zucc by aseptic techniques and the analysis of the culture fluid from the fermentation of fungus was carried out by high performance liquid chromatography (HPLC). RESULTS: Endophytic fungus was obtained from the bark of Taxus Cuspidata Sieb et Zucc and the chemical analysis showed that the culture of fungus contain taxol compounds. CONCLUSION: Endophytic fungus which can produce taxol compounds exists in the bark of Taxus Cuspidata Sieb et Zucc.

Chromatography, High Pressure Liquid↗
PubMed2000

Prenatal exposure to high levels of glucocorticoids increases the susceptibility of cerebellar granule cells to oxidative stress-induced cell death.

There is growing concern that prenatal exposure to excessive glucocorticoids may have deleterious effects on the development of various organs, including the nervous system. This study aimed at evaluating whether prenatal exposure to high levels of glucocorticoids might produce long-term effects on neuronal cell survival. Pregnant rats were injected i.p. with 0.1 mg/kg dexamethasone (DEX) from day 14 postconception, and cerebellar granule cells (CGC) were prepared from 1-week-old rats from DEX-treated and control dams. After 7 days in culture, cells were exposed to H(2)O(2), methylmercury, or colchicine at concentrations known to induce apoptotic cell death. After exposure to H(2)O(2) or methylmercury, both inducing oxidative stress, the number of apoptotic cells was significantly higher in DEX- than in control-CGC. Because mitochondria play a key role in apoptosis, mitochondrial function was investigated, and a decrease in the threshold level of Ca(2+) necessary for induction of mitochondrial permeability transition, in Ca(2+) accumulation rate, and in oxygen consumption was detected in DEX-CGC. Moreover, the activity of the antioxidant enzyme catalase was significantly decreased in DEX-CGC. A similar decrease in catalase activity was observed in cerebellar homogenate from newborn and 40-day-old DEX-rats. In conclusion, these results indicate that prenatal exposure to high levels of glucocorticoids induces long-lasting changes in CGC rendering them more sensitive to oxidative stress. With the increasing use of multiple doses of glucocorticoids in preterm infants, the possibility that prenatal exposure to excess glucocorticoids may lead to long-term neurological consequences becomes a relevant issue.

Animals↗
PubMed2000

Mechanisms of immunomodulation by glatiramer acetate.

OBJECTIVE: To define the mechanism of action of glatiramer acetate (GA; formerly known as copolymer-1) as an immunomodulatory treatment for MS. BACKGROUND: The proposed mechanisms of action of GA include 1) functional inhibition of myelin-reactive T cells by human leukocyte antigen (HLA) blocking, 2) T-cell receptor (TCR) antagonism, and 3) induction of T helper 2 (Th2) immunomodulatory cells. In this report, the authors examined the effects of GA on the functional activation of human T-cell clones (TCC) specific for myelin basic protein (MBP) and for foreign antigens. Several questions were addressed: Is the inhibitory effect of GA specific for autoantigens? Is it mediated by blocking the interaction between peptide and HLA molecule? Is GA a partial agonist or TCR antagonist, or does it induce anergy? Does it induce Th2 modulatory T cells? METHODS: The effects of GA on antigen-induced activation of human TCC specific for MBP, influenza virus hemagglutinin, and Borrelia burgdorferi were studied by proliferation and cytokine measurements, TCR downmodulation, and anergy assays. GA-specific TCC were generated in vitro from the peripheral blood of patients and healthy controls by limiting dilution. RESULTS: GA more strongly inhibited the proliferation of MBP, as compared with foreign antigen-specific TCC; in some MBP-specific TCC, the production of Th1-type cytokines was preferentially inhibited. In addition to HLA competition, the induction of anergy, but not direct TCR antagonism, was observed. Numerous GA-specific TCC were generated from the peripheral blood of both MS patients and normal controls, and a fraction of these showed a Th2 phenotype. CONCLUSIONS: This study confirms a preferential inhibitory effect of GA on autoreactive TCC. With respect to cellular mechanisms, although HLA competition appears to play the most important role in functional inhibition in vitro, a direct effect on the TCR may be involved at least in some autoreactive T cells as shown by anergy induction. Although not confirmed at the clonal level, it is demonstrated further that GA induces T cells that crossreact with myelin proteins. GA-specific, Th2-modulatory cells may play an important role in mediating the effect of the drug in vivo.

Adjuvants, Immunologic↗