Search PubMed⌕ Search

Biomedical subjects

C Wu

Publications and source records attributed to C Wu.

At least 379 records · Page 21Linked to original sources
PubMed1997

Protective effect of green tea extract and tea polyphenols against the cytotoxicity of 1,4-naphthoquinone in isolated rat hepatocytes.

The cytoprotective effect of green tea extract and its phenolic compounds against 1,4-naphthoquinone-induced hepatotoxicity was evaluated in primary cultured rat hepatocytes. After exposure to 1,4-naphthoquinone, lactate dehydrogenase (LDH) leakage and cell viability were both improved by the presence of the tea extract and tea polyphenols. This cytoprotective effect was related to the structure of tea polyphenols, the galloyl group of (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate being particularly effective. The production of liquid peroxidation by 1,4-naphthoquinone was not inhibited by the tea extract nor by tea polyphenol addition. After 2 h of incubation, the protein thiol concentration was reduced by 1,4-naphthoquinone, but this reduction was prevented by the tea extract and tea polyphenols. The reduction in protein thiol content of the cells closely paralleled the LDH leakage and loss of cell viability. These results suggest that the mechanism of protection by tea polyphenols against 1,4-naphthoquinone-induced toxicity to rat hepatocytes was due to the maintenance of protein thiol levels.

Animals↗
PubMed1997

Asian, American, and deaf: a framework for professionals.

The authors present a multicultural framework for thinking about, assessing, and working with Deaf people from Asian and Asian Deaf backgrounds. Emphasis is placed on cultural awareness and cultural competence for professionals and on building bridges across cultural networks.

Asian↗
PubMed1997

A preliminary evaluation of the lunar expert-XL for bone densitometry and vertebral morphometry.

We have evaluated the Lunar Expert-XL for standard bone mineral densitometry (BMD) and for morphometric imaging of the spine in the lateral projection. The short-term precision in vitro of the Expert-XL for BMD measurements was 0.7% for the Hologic and European spine phantoms, and the long-term stability (15-month) measurements had a 1.1% coefficient of variation. The precision in vivo for three operators examining a group of 10 premenopausal women was 0.9-1.5% for lumbar spine (L2-L4), 1.7-2.2% for the femoral neck, and 0.9% for the total hip region of interest. For a group of nine postmenopausal women, the lumbar spine, femoral neck, and total femur precision ranges were 2.0-2.4, 1.2-2.9, and 1.6-1.7% respectively. For L2-L4, BMD comparison between the Expert-XL and DPX-L yielded a correlation coefficient of r = 0.98, a slope of 0.86, and an intercept of 0.139 g/cm2. The femoral neck results were r = 0.92, slope = 1.00, and intercept = 0.03 g/cm2. In an evaluation of the Expert-XL for lateral morphometry, we employed a group of 16 postmenopausal women. Comparison of vertebral dimensions between the Expert-XL and radiographic morphometry showed strong agreement (r = 0.97), but the interobserver variability for vertebral height was higher for the Expert-XL than for radiographs (3-5% vs. 1-2%). In a subset of four women who had repeat scans, the interscan precision for measuring vertebral dimensions was 1.9, 4.1, and 43% for the L1-L4, T12-T8, and T7-T5 levels respectively. In the Expert-XL images, it was possible to identify clearly L4-T4 in 10 of 16 patients and L4-T6 in 15 of 16, indicating potential utility for vertebral fracture prescreening.

Absorptiometry, Photon↗
PubMed1997

[DNA content correlation with the prognosis of pheochromocytoma: 10 cases report].

We investigated the relationship between DNA ploidy and the prognosis of pheochromocytoma. DNA ploidy studies on paraffin-embedded archival specimens from ten cases of pheochromocytoma were performed by flow cytometry according to Hedley's method. Clinical features and pathological results were investigated and follow-up was made. The values of DNA content in assessment of the prognosis of the tumor were discussed. Flow cytometry examination showed that seven cases had aneuploid, two deploid and one tetraploid. The malignent case was tetraploid, and died from matastasis to the bone. The other cases had a benign process. The examination of DNA content is of value in the assessment of the prognosis of pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1997

[The effect of recombinant human growth hormone on thyroid function in patients with growth hormone deficiency].

To evaluate the effect of growth hormone treatment on thyroid function of growth hormone deficient children, 19 (18M/1F) euthyroid children of growth hormone deficiency (GHD) were treated with Genotropin, a recombinant human growth hormone (rhGH) for 12 months. rhGH was injected subcutaneously with a daily dosage of 0.1 IU/kg. All the patients were diagnosed by two GH provocative stimulating tests with the serum GH peak level < 7 micrograms/L. During the treatment, blood was drawn before or 6 and 12 months after the initiation of therapy to measure serum T3, T4, FT3, FT4, rT3 and thyroid-stimulating hormone (TSH) levels. In the meantime, thyrotropin releasing hormone (TRH) stimulating test was performed by an i.v. injection of 200 micrograms synthetic TRH. The results showed that (1) the average serum levels of T4 and FT4 decreased significantly 6 at the 6th and 12th month (P < 0.001), while the serum FT3 level decreased only at the 6th month (P < 0.05). The serum T3, rT3 and TSH concentrations remained unchanged. (2) 8 euthyroid patients (45%) became subclinical hypothyroidism after 12 months' treatment with rhGH for their serum FT4 levels fell to below the normal range. The 19 patients were divided into thyroid function normal (n = 11) and subnormal group (n = 8) according to their posttreatment thyroid functions. (3) The TSH response to TRH was evaluated by the area under the curve (AUC) of serum TSH. The average AUC was greater in the subnormal group than in the normal group whether before or 6 and 12 months after the treatment. The greater TSH response to TRH among patients with decreased posttreatmental FT4 levels suggests that latent TRH deficiency has already existed, which may be the pathogenetic basis of the hypothyroidism developped after rhGH treatment. Thus the thyroid function of GHD patients should be monitored during rhGH treatment in order that the thyroxine replacement therapy can be given in time.

Child↗
PubMed1997

[The use of enthalpy-entropy compensation in the study of retention mechanism of aromatic positional isomers].

In this paper, the thermodynamic parameters of the separation process of six groups of aromatic positional isomers on nine crown ether polysiloxane, OV-1701 and Carbowax-20M capillary chromatographic columns have been investigated systematically. The Gibbs free energies for every compound at harmonic mean temperature, calculated were given. The enthalpy-entropy compensation effect of these chromatographic process was examined by using of Krug's ANOVA method. In the light of the axiom of extrathermodynamic relationship, the retention mechanisms of these aromatic compounds on each crown ether stationary phase have been expounded. We come to conclusion that, as a whole, the separation of various aromatic isomers on crown ether stationary phase is governed by multiple retention mechanisms, but the separation of some groups of aromatic isomer on the same crown ether phase can be led to single interaction mechanism since the phenomena of enthalpy-entropy compensation is observed. It may be that a kind of interaction parameter, which varies with the configuration of solutes, plays the main role in retention process of these isomers.

English Abstract↗
PubMed1997

A new calixcrown polysiloxane stationary phase for capillary gas chromatography.

A new calixcrown polysiloxane gas stationary phase (M-C[4]C-5PSO) in which calixcrown monomers lie in the main chain of polysiloxane was first synthesized. The calixcrown polysiloxane exhibits high thermostability and good separation abilities for nitro, chloro- and methyl substituted benzene or phenol isomers. The application of M-C[4]C-5PSO and the separation mechanism will be further studied.

Journal Article↗
PubMed1997

[Quantitative determination of 7-ketocholesterol in human fetal liver cell supernatant and lysate by high performance liquid chromatography].

7-Ketocholesterol (7-KC), which is a major oxidation product of cholesterol and is selective cytotoxic to tumour cells, was isolated from human fetal liver. A fast, sensitive method of high performance liquid chromatography for the quantitation of 7-KC has been developed and applied to the determination of 7-KC in human fetal liver cell suspension. In this procedure a mixture of 2 : 1 chloroform-methanol (V/V) was used as extraction solvent. The extract was washed with distilled water and then evaporated to dryness under N2. An adsorption liquid chromatographic system used included mu-Porasil SiO2 column, hexane : iso-propanol (91 : 9) mobile phase and UV detector at 233nm. It was found that the level of 7-KC in human fetal liver cell supernatant was higher than in liver lysate.

Chromatography, High Pressure Liquid↗
PubMed1997

[Gas chromatographic analysis of methyl methacrylate and methanol in its esterification mixture].

A fast, simple and accurate gas chromatographic method is established for determining the content of methyl methacrylate (MMA) and methanol in the esterification mixture of methacrylic acid with methanol in the presence of sulfuric acid. In the measurement, polyethylene glycol-20M/sodium hydroxide was adopted as liquid phase, coated on the acid-washed 201 pink support. n-Heptane was used as the internal standard and the correction factors of MMA and methanol obtained were 1.65 and 4.10, respectively. It is significant for this method to be used to control MMA production by acetone cyanohydrin method and to improve the production technology.

English Abstract↗
PubMed1997

A case of sulfhemoglobinemia and emergency measurement of sulfhemoglobin with an OSM3 CO-oximeter.

We describe a case of sulfhemoglobinemia associated with toxic paint ingestion. Blood gases, oxygen content, and fractional hemoglobin derivatives were assayed with Radiometer 520 and OSM3 instruments. Although the CO-oximeters indicated the presence of sulfhemoglobin (SulfHb), the results were not quantitative. An OSM3 service software program was activated to obtain the actual concentrations of the hemoglobin fractions. Subsequently, we evaluated the performance of the OSM3 service program for the analysis of SulfHb by performing precision studies and comparing OSM3 results with those of an AVL 912 CO-oximeter. Retrospectively, we determined that the patient's specimens contained 6% SulfHb. There was an obvious deviation between standard OSM3 oxyhemoglobin fraction measurements and those obtained by using its service program-the effect of a high SulfHb content.

Adult↗
PubMed1997

Roles of integrins in fibronectin matrix assembly.

Fibronectin (Fn) matrix assembly is a dynamic cellular process in which the soluble dimeric Fn molecules are assembled into insoluble, disulfide bond stabilized fibrillar polymeric matrix. Fn matrix assembly requires specific Fn binding integrins. Several Fn binding integrins that are capable of mediating Fn matrix assembly have been identified. They include alpha5beta1, alphaIIb(beta3) and alpha(v)beta3 integrins. Cells regulate the matrix assembly process not only by controlling cell surface expression level of the Fn binding integrins but also by modulating Fn binding and cytoskeleton binding activities of the integrins. A major challenge of future studies is to delineate the signal transduction pathway that regulates Fn matrix assembly.

Amino Acid Sequence↗
PubMed1997

Factors influencing the in vivo pharmacokinetics of peptides and antibody fragments: the pharmacokinetics of two PET-labeled low molecular weight proteins.

Monoclonal antibodies (MoAbs) were proposed as candidates for selective tumor targeting based on their high binding affinity for tumors and the absence of binding by normal tissue. However, the exclusive and complete transport of the drug have been found lacking in the use of intact MoAbs, especially in the case of solid tumors. Smaller fragments that maintained the desiderable tumor targeting characteristics appear to have an advantage because of the increase in whole body clearance and the shorter time to maximum target to non-target ratio. But the binding to normal tissue increases as the molecular weight or size decreases, especially in the kidney, because the glomerular sieving coefficient increases. We have used two approaches to overcome the normal tissue binding: a) the use of lysine to block the uptake of the Low Molecular Weight Proteins (LMWP) in the proximal tubules and b) the labeling of different amino acids in the LMWP to alter the residence time in the kidney. The combination of these two methods, blocking the uptake with lysine and shortening the residence time of the radioactive compound produced in the kidney, can lead to substantially decreased normal kidney targeting. The lysine paradigm was effectively demonstrated using 18F-labeled anti-Tac dsFv. Shortening the residence time was illustred by comparing the kinetics of the lysine catabolite versus the methionine metabolite. Furthermore, the rapid pharmacokinetics of the LMWP are consistent with the use of the shorter half-lives of PET radionuclides and the concomitant increase in quantitation and sensitivity afforded by PET.

Animals↗
PubMed1997

Transposon tagging in rice.

To develop an efficient gene isolation method for rice we introduced the maize Ac/Ds system into rice. Extensive analysis of their behavior in rice for several generations indicated that Ac and Ds in the presence of Ac transposase gene actively transpose in rice. A wide spectrum of mutations affecting growth, morphogenesis, flowering time and disease resistance have been obtained in the population carrying Ac/Ds and some of them were genetically analyzed. Main efforts are currently being made to isolate genes responsible these mutations. In addition, a number of Ac/Ds were mapped on chromosomes and mapped elements will be used in the future for directed tagging of genes with known chromosomal positions.

Cloning, Molecular↗
PubMed1997

Radioimmunotherapy targeting of HER2/neu oncoprotein on ovarian tumor using lead-212-DOTA-AE1.

UNLABELLED: The specificity, toxicity and efficacy of lead (212Pb) radioimmunotherapy were evaluated in nude mice bearing the SK-OV-3 human ovarian tumor cell line expressing the HER2/neu proto-oncogene. METHODS: The therapeutic agent used was the tumor-specific anti-HER2/neu monoclonal antibody AE1 conjugated to 212Pb, 212Bi being the daughter and thus the source of the alpha-particle and beta emissions. A bifunctional derivative of tetraazacyclododecanetetraacetic acid (p-SCN-Bz-DOTA) was used to couple 212Pb to the anti-HER2/neu monoclonal antibody AE1. The chelating agent did not alter the binding affinity to its antigenic target or the pharmacokinetics and tissue distribution of the AE1 antibody. Toxicity and therapeutic efficacy of 212Pb-AE1 were evaluated in nude mouse ascites or solid tumor models, wherein SK-OV-3 cells were administered i.p. or s.c., respectively. RESULTS: The dose-limiting acute toxicity after i.v. administration of 212Pb-AE1 was bone marrow suppression, which was observed at doses above 25 microCi. Therefore, doses of 10 and 20 microCi were used in efficacy trials. The i.p. administration of 212Pb-AE1 3 days after i.p. tumor inoculation led to a significant (P2 = 0.015) prolongation of tumor-free survival. In a second model, i.v. treatment with 212Pb-AE1 3 days after s.c. tumor inoculation prevented subsequent tumor development in all animals treated with 10 or 20 microCi of 212Pb-AE1 (P2 = 0.002 compared to control groups). This efficacy in the adjuvant setting was antibody specific because treatments with equivalently labeled control antibody or unlabeled AE1 antibody or no treatment were less effective. The rate of growth of small (mean tumor volume, 15 mm3) SK-OV-3 tumors was modestly inhibited. However, tumor growth was not inhibited in mice bearing larger (mean tumor volume, 146 mm3) SK-OV-3 tumors by the administration of a single dose of 10 or 20 microCi of 212Pb-AE1. CONCLUSION: Lead-212-AE1 as an intact radiolabeled monoclonal antibody may be of only modest value in the therapy of bulky solid tumors due to the short physical half-life of 212Pb and time required to achieve a useful tumor-to-normal tissue ratio of radionuclide after administration. However, the radiolabeled monoclonal antibody may be useful in therapy of tumors in the adjuvant setting. Furthermore, 212Pb may be of value in select situations, including treatment of leukemia, intercavitary therapy or strategies that target vascular endothelial cells of tumors.

Animals↗
PubMed1997

Serological investigation on human trichinellosis spiralis in Hubei Province of PR China.

PVC-ELISA for detection of human trichinellosis and its value of field application was explored during 1988-1994. Sera of 56 cases of clinically confirmed trichinellosis were tested for serum Trichinella antibodies by way of PVC-ELISA, and the positive rate was 100%. When the sera of 80 cases of healthy persons from non-endemic areas were tested for trichinellosis, they were all negative. For the purpose of exploring the cross-reaction of PVC-ELISA used for detection of trichinellosis, sera from 144 cases of other parasitoses were tested. Among them, the sera of 80 cases of schistosomiasis japonica for trichinellosis were negative; 30 cases of paragonimiasis and 30 cases of clonorchiasis were also negative. Among sera of 4 cases of cysticercosis, there was only one positive. The results showed that PVC-ELISA for trichinellosis had a high sensitivity and specificity. For field application, a population of 800 from endemic areas were examined by PVC-ELISA, 85 (10.63%) were positive. The infected persons were mainly in Xiangfan region of Hubei Province. The percentage of the positive of trichinellosis in Xiangfan region was 64.71% (55/85). The positive rate of males and females was 13.41% (57/425) and 7.47% (28/375), respectively. There was a difference among the age groups, with the highest in those > or = 20 years. The findings of this field investigation suggested that the infection rate of trichinellosis spiralis was high in this province, especially in the Xiangfan region; and that PVC-ELISA was suitable for field application. The emphasis of trichinellosis control and research of this province should be in the Xiangfan region.

China↗
PubMed1997

[Changes in gamma-amino-butyric acid and N-methyl-D-aspartic acid receptor-gated currents from freshly isolated hippocampal CA1 pyramidal neurons of hepatic encephalopathy rats].

OBJECTIVE: To explore the effects of the changes of the amino acid receptor-gated ion-channel currents on the pathogenesis of hepatic encephalopathy (HE). METHODS: Using rapid drug applicating device, we added 50 mumol/L gamma-amino-butyric acid (GABA) or 1 mmol/L N-methyl-D-aspartic acid (NM-DA) + 10 mumol/L Glycine (Gly) to the surrounding of freshly isolated rat hippocampal CA1 pyramidal neurons to induce receptor-gated ion-channel currents, which was recorded by whole-cell voltage-clamp technique. RESULTS: The intensity of the GABAA-receptor mediated inward Cl- current of hippocampal CA1 pyramidal neurons of HE rats (413.3 +/- 436.8 pA, n = 31) was stronger than that of the controls (233.4 +/- 179.7 pA, n = 28, t = 2.1049, P < 0.05), and the appearance of the Cl- current in HE rats was more frequent than that in the controls. The intensity of the NMDA-receptor gated inward current in HE rats (408.5 +/- 317.2 pA, n = 37) was weeker than that in the controls (882.6 +/- 896.5 pA, n = 26, t = 2.5851, P < 0.05), but the difference of their channel opening frequency was not significant. CONCLUSIONS: The changes of the amino acid receptor-gated ion-channel currents play an important role in the pathogenesis of hepatic encephalopathy.

Action Potentials↗