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Biomedical subjects

J Y Zhao

Publications and source records attributed to J Y Zhao.

At least 19 recordsLinked to original sources
PubMed2005

Anharmonic motions of Kr in the clathrate hydrate.

The anomalous glass-like thermal conductivity of crystalline clathrates has been suggested to be the result of the scattering of thermal phonons of the framework by 'rattling' motions of the guests in the clathrate cages. Using the site-specific (83)Kr nuclear resonant inelastic scattering spectroscopy in combination with conventional incoherent inelastic neutron scattering and molecular-dynamics simulations, we provide unambiguous evidence and characterization of the effects on these guest-host interactions in a structure-II Kr clathrate hydrate. The resonant scattering of phonons led to unprecedented large anharmonic motions of the guest atoms. The anharmonic interaction underlies the anomalous thermal transport in this system. Clathrates are prototypical models for a class of crystalline framework materials with glass-like thermal conductivity. The explanation of the unusual molecular dynamics has a wide implication for the understanding of the thermal properties of disordered solids and structural glasses.

Computer Simulation↗
PubMed2004

An autosomal genomic scan for loci linked to type 2 diabetes in northern Han Chinese.

We report the results of a genome-wide scan conducted in 219 individuals from 34 large multiplex nuclear pedigrees from the northern Han Chinese population at an average resolution of about 10 cM. Nonparametric two-point and multipoint linkage analyses were performed to detect evidence of linkage with type 2 diabetes in this study. On chromosome 1 four regions showed evidence of linkage with type 2 diabetes in northern Han Chinese. Of these regions a marker D1S193 (73 cM) showed evidence of linkage (two-point nonparametric linkage 2.409), and another region (around 190 cM) was a replication of several other studies performed in different ethnic populations. Evidences of linkage have been confirmed by typing additional markers (average distance 1-5 cM) flanking these two positive regions on chromosome 1. We also found indication of linkage with type 2 diabetes on chromosomes 2, 10, 12, 18, 20, and 22 by two-point linkage analyses.

Adult↗
PubMed2001

Potential of capillary electrophoresis, tandem mass spectrometry and coupled capillary electrophoresis-tandem mass spectrometry as diagnostic tools.

Urine and blood samples from patients with known metabolic disorders have been analyzed by CE, MS-MS and CE-MS-MS. For the identification of defects in acylcarnitine metabolism, blood spots on filter paper were analyzed using an MS-MS "neonatal screening" approach. Direct CE-MS-MS analysis was used for the analysis of urine samples from patients with different metabolic disorders, including galactosemia, neuroblastoma, Zellweger syndrome, propionic acidemia and alcaptonuria. The sensitivity of the CE-MS-MS method was increased by use of multiple reaction monitoring.

Electrophoresis, Capillary↗
PubMed2001

Analysis of tamoxifen and its metabolites in synthetic gastric fluid digests and urine samples using high-performance liquid chromatography with electrospray mass spectrometry.

We report on the transformation of tamoxifen at 37 degrees C in synthetic gastric fluid as studied by high-performance liquid chromatography with triple quadrupole mass spectrometry. The major transformation products detected were (E)-isomer of tamoxifen, metabolite D, and several unidentified components having m/z 404. Addition of pepsin to the gastric fluid inhibited formation of all of these products. We analyzed several urine samples from breast cancer patients undergoing tamoxifen treatment. Metabolite D was identified in the urine samples and in the gastric fluid digest at a retention time of 22.0 min eluting from a reversed-phase HPLC column. Although several metabolites were found in all the urine samples of patients, some metabolites were detected in one sample but not others, suggesting tamoxifen metabolism varies in patients.

Breast Neoplasms↗
PubMed2001

Forbidden X-ray wavefields of three-beam Bragg reflections from thick crystals.

A detailed analysis of a three-beam diffraction dispersion surface is performed to study the forbidden wavefields of thick-crystal Bragg reflections. From the asymptotic transition between two- and three-beam diffraction, it is found that the excitation state of each wavefield can be accurately determined with the two-beam criterion. Consequently, Bragg-case three-beam diffraction from thick crystals is either a four-mode diffraction process for the Bragg-Laue geometry or a two-mode process for the Bragg-Bragg geometry, and the amplitudes of the excited wavefields can be completely determined by the entrance boundary conditions. Based on this picture, the intrinsic mechanisms underlying three-beam Bragg reflections are clearly illustrated.

Journal Article↗
PubMed2000

[Effects on fiber regeneration following facial nerve transection treated with NOS antagonist].

OBJECTIVE: To elucidate the role of nitric oxide synthase antagonist, N-Nitro-L-Arginine Methyl Ester (L-NAME) in the regeneration of facial nerve following facial nerve transection. METHOD: The facial nerves of 40 guinea pigs were exposed and a segment of the nerve at 3 mm length were excided. The two ends of the transected nerve were sutured and enveloped in a silicone tubule to form a regeneration chamber. L-NAME and saline were respectively injected into the regeneration chambers just after transection. The experiments were observed quantificational by the means of axon and myelin staining under light microscope. RESULT: The findings in the work indicate that inhibition of NOS with L-NAME substantially better myelinated facial nerve regeneration than that associated with administration of saline. CONCLUSION: L-NAME improve the regeneration of myelinated fibers. The mechanism seems to be related to the blockade of NO's neurotoxicity.

Animals↗
PubMed1998

A high-temperature environmental chamber for nuclear-resonant Bragg scattering studies.

A compact environmental chamber with a furnace operating in the range from room temperature to about 900 K has been built for a high-temperature nuclear-resonant Bragg scattering study. The compact size (75 mm diameter and 70 mm depth) allows an external magnetic field to be applied from outside permanent Nd-Fe-B alloy magnets; a magnetic field up to 1000 G has been obtained. The chamber can be mounted on a precise theta-2theta goniometer so that in situ observations of X-ray diffraction from a single crystal can be carried out. The temperature is measured by two thermocouples placed at the top and back of the sample and controlled by a PID controller. The temperature fluctuation of the chamber is less than +/-1 K.

Journal Article↗
PubMed1997

Analysis of domoic acid and isomers in seafood by capillary electrophoresis.

Methods for the analysis of domoic acid (DA) based upon capillary electrophoresis (CE) combined with UV absorbance detection were investigated. DA could be analyzed using bare fused-silica capillaries in either the cationic or anionic mode with acidic or basic buffer systems, respectively. Highest performance, in terms of both separation efficiency and analysis time, was achieved with phosphate or borate buffers at a pH of approximately 9. The addition of beta-cyclodextrin to the borate buffer permitted a separation of DA and several of its isomers (isodomoic acids) that was superior to that achieved with liquid chromatography (LC). The optimum background electrolyte for the separation was 22.5 mM sodium tetraborate at pH 9.2 with mM beta-cyclodextrin. In addition, an extraction and clean-up procedure was developed and tested with mussels, clams and anchovies. Aqueous methanol extraction of samples followed by a tandem strong anion and strong cation exchange clean-up provided an extract that was completely compatible with CE analysis. A mass detection limit of 3 pg of DA injected and a method detection limit of 150 ng/g in tissues could be achieved. Comparison with LC showed that comparable precision and accuracy could be attained by the two techniques.

Animals↗
PubMed1996

[Relationship between lipid peroxidase and superoxide dismutase in bronchoalveolar lavage fluid and pulmonary qi deficiency syndrome].

Investigating the levels of lipid peroxidase (LPO) and superoxide dismutase (SOD) in serum, bronchoalveolar lavage fluid (BALF) and alveolar macrophage (AM) were determined in 40 chronic bronchitis patients with Pulmonary Qi Deficiency (PQD) Syndrome and 36 normal subjects. Results showed: (1) No significant differences were found between PQD syndrome and normal subjects on serum SOD or LPO levels. (2) Patients with PQD Syndrome. LPO level in BALF was significantly higher, and SOD significantly lower, when compared with normal subjects. (3) Through correlation analysis, it was found in BALF that SOD level was markedly correlated with AM, while LPO was significantly correlated with neutrophil. In short, SOD and LPO in BALF play an important role in the development of the PQD Syndrome, and are good indications in evaluating the PQD Syndrome.

Adult↗
PubMed1995

Fibronectin and hyaluronan in bronchoalveolar lavage fluid from young patients with chronic obstructive pulmonary diseases.

Fibronectin (FN) and hyaluronan (HA) in bronchoalveolar lavage fluid (BALF) and FN released by alveolar macrophages (AM) were examined in 7 nonsmoking healthy control subjects, and 20 smoking patients with chronic obstructive pulmonary diseases (COPD). All patients and subjects were no more than 40 years old. According to the 95% confidence limits of HA and FN in BALF from nonsmoking healthy control subjects, the smoking patients were divided into two groups, those who had HA and FN levels within the limits for nonsmoking controls were classified as the first group (group 1) and those with levels above the control limits were classified as the second group (group 2). Our data showed that the concentrations of HA and FN in BALF and FN released by AM were significantly higher in group 2 than in group 1 patients. There were also significant differences between the two groups in pulmonary function measurements (DLco, FEV1, and FEV1/FVC) which were lower in group 2. HA levels in group 2 patients correlated directly with counts of inflammatory cells in BALF (BALF cells/ml, and numbers/ml of total cells, macrophages, neutrophils and lymphocytes), and the concentration of FN released by AM, and showed an inverse correlation with pulmonary function (DLco and FEV1/FVC). Our results suggest that the inflammatory repair response and fibrosis may play a role in the development of emphysema in young patients with COPD.

Adult↗
PubMed1994

Separation of aminated monosaccharides by capillary zone electrophoresis with laser-induced fluorescence detection.

The six most abundant hexoses found in mammalian carbohydrates were derivatized to serve as standards for an oligosaccharide sequencing project. Glucose, galactose, mannose, and fucose were reductively aminated to produce 1-amino-1-deoxy alditols. Standards for N-acetylglucosamine and N-acetylgalactosamine were synthesized by reducing glucosamine and galactosamine to 2-amino-2-deoxy alditols. The monosaccharides were labeled with 5-carboxytetramethylrhodamine succinimidyl ester. By carefully adjusting the separation buffer, we have separated the sugar derivatives completely. The detection limit is 100 molecules of labeled sugar with a post-column laser-induced fluorescence detection in a sheath flow cuvette.

Amination↗
PubMed1994

Detection of 100 molecules of product formed in a fucosyltransferase reaction.

We present the detection of 100 molecules of enzyme substrate and product. A fucosyltransferase and a fucosidase were used to add and remove, respectively, a monosaccharide from a synthetic oligosaccharide fluorescently labelled with tetramethylrhodamine. The reaction was followed by use of capillary zone electrophoresis, to separate the product and reactant, with laser-induced fluorescence detection. These are the most sensitive enzyme assays reported to date and six orders of magnitude more sensitive than any reported for these two enzymes. This simple technology allows high-sensitivity determination of the activity of any enzyme for which a fluorescent substrate can be synthesized, and brings within reach the ability to assay glycosyltransferase activities in single cells.

Carbohydrate Conformation↗
PubMed1994

Two multidrug-resistant Friend leukemic cell lines selected with different drugs exhibit overproduction of different P-glycoproteins.

Two Friend leukemic multidrug-resistance (MDR) cell lines were established by exposure to stepwise increased concentrations of rhodamine-123 (RHO) (cell line RR-30) or Adriamycin (ADR) (cell line ARN-15). RR-30 displays preferential resistance to RHO, whereas ARN-15 is more resistant to ADR. The levels of resistance to other MDR drugs and reversibility by verapamil between these two MDR cell lines were somewhat different. Southern blot, RNase protection, and Western blot analysis using gene-specific probes demonstrated that RR-30 and ARN-15 cells preferentially amplified the mdr1 and mdr3 genes, respectively, leading to overexpression of the corresponding P-glycoproteins (p-gp). Our results suggest that members of the mdr gene family can be amplified independently by using different selecting agents, which could be responsible for the differences in the sensitivities to these selecting agents as well as to these MDR drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

[Relationship between local effect of cortisol used by chronic bronchitis patients and syndrome differentiation in TCM].

Serum cortisol levels and bronchoalveolar lavage fluid (BALF) from 105 patients with chronic obstructive pulmonary disease (COPD) and 36 normal subjects were examined and the relationship between cortisol inhibiting the TXB2 secreted by alveolar macrophage (AM) and the theory of Syndrome Differentiation in TCM was explored. Results showed: (1) No significant differences were found between chronic bronchitis and normal subjects on cortisol levels in serum, but in BALF, cortisol levels was significantly lower in Lung Qi Deficiency when compared with that in normal subjects. (2) the levels of cortisol inhibiting the TXB2 secreted by AM which were significantly lower in chronic bronchitis when compared with that in control. In short, the amount and function of cortisol in BALF were significantly different in various syndromes in TCM of chronic bronchitis.

Adult↗
PubMed1993

Effects of selenium deficiency on Ca transport function of sarcoplasmic reticulum and lipid peroxidation in rat myocardium.

Two groups of weanling Sprague-Dawley rats were fed a low-selenium basal diet (Se 0.009 mg/kg) and the same diet supplemented with sodium selenite (Se 0.25 mg/kg), respectively, for 1, 2, and 3 months. At each feeding time, the Ca(2+)-ATPase activity, Ca2+ uptake rate and the capacity of Ca2+ uptake in isolated cardiac sacroplasmic reticulum from the Se-deficient rats were decreased significantly compared to those from the Se-supplemented rats, the contents of lipid peroxide in postmitochondrial supernatant and isolated sarcoplasmic reticulum from the Se-deficient rats were significantly higher than that from Se-supplemented rats. Compared to the Se-supplemented rats, the cytosolic glutathione peroxidase activity in Se-deficient rats decreased significantly. In addition, significant linear negative correlations of lipid peroxide in postmitochondrial supernatant to sarcoplasmic reticular Ca(2+)-ATPase activity, Ca2+ uptake rate and to whole blood selenium concentration were observed. The results suggest that the enhancement of lipid peroxidation via the depressed glutathione peroxidase activity might be responsible for the decrease of Ca(2+)-ATPase and Ca2+ uptake activities in sarcoplasmic reticulum in Se-deficient animals.

Animals↗
PubMed1993

Modulation of multidrug resistance gene expression by dexamethasone in cultured hepatoma cells.

Considerable evidence has accumulated indicating that overexpression of P-glycoproteins encoded by the multidrug-resistance (mdr) genes is responsible for the development of collateral resistance to a number of structurally and functionally dissimilar cytotoxic compounds in animal cells. There are three mdr genes (mdr1, mdr2, and mdr3) in the mouse genome and two (MDR1 and MDR2) in the human genome; however, only two mouse genes (mdr1 and mdr3) and one human gene (MDR1) can confer multidrug resistance upon transfection into otherwise drug-sensitive cells. Using RNase protection assay we report here that the steady-state levels of mdr1 and mdr3 messenger RNA were elevated in mouse hepatoma cells treated with dexamethasone (Dex); whereas no induction of mdr2 gene was found. Western blot analyses using anti-mdr1 and anti-mdr3 antibodies revealed that the encoded proteins appeared to be increased, but at much reduced levels. The induction was time and Dex concentration dependent. Nuclear run-on experiments demonstrated that the induction was at least in part by transcriptional control. The induction apparently required new protein synthesis since no increases in mdr1 and mdr3 transcripts was found when cultured cells were simultaneously treated with Dex and cycloheximide. Neither mdr1 nor mdr3 gene was induced in the Dex-treated nonhepatoma cell lines, LMtk- and NIH3T3. Similarly, MDR1 messenger RNA levels were elevated in the Dex-treated human hepatoma line, HepG2, but not in the nonhepatoma, HeLa. This study demonstrated that the hormonal regulation of mdr gene expression is gene and cell type specific.

3T3 Cells↗
PubMed1992

Attachment of a single fluorescent label to peptides for determination by capillary zone electrophoresis.

Complicated electropherograms are produced in the separation of fluorescently labeled peptides. Incomplete labeling of epsilon-amino groups on lysine residues results in the production of 2n-1 reaction products, where n is the number of alpha and epsilon amino groups in the peptide. A single label is attached to the peptide by first taking the peptide through one cycle of the Edman degradation reaction. All epsilon-amino groups are converted to the phenyl thiocarbamyl and the cleavage step exposes one alpha-amino group at the N-terminus of the peptide; the fluorescent label is attached to the N-terminus.

Amino Acid Sequence↗