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Biomedical subjects

C Zhao

Publications and source records attributed to C Zhao.

At least 91 records · Page 5Linked to original sources
PubMed2001

[Studies on the synthesis and bioactivity of alpha-alkylaminobenzyl-phosphonic acids].

AIM: To search for some substituted benzyl phosphonic acids as leading compounds with inhibiting effect on osteoclast formation. METHODS: Target compounds were prepared from aromatic aldehydes, primary amine and phosphorous acid using tetramethylenesulfone as solvent via Arbuzov type reaction. The effect on inhibiting the formation of osteoclast-like cells (OLC) of related compounds was studied by incubating the extract of rat femur marrow. RESULTS: Ten compounds of alpha-alkylaminobenzyl phosphonic acids have been synthesized and identified by MS or 1HNMR analysis. Three (2, 8 and 9) of them were found to have notable effect on the inhibition of OLC formation (P < 0.01). CONCLUSION: Among the present substituted benzyl phosphonic acids, the increased aromaticity and hydrophobicity (such as compound 9) can remarkably enhance the ability to inhibit OLC formation.

Animals↗
PubMed2001

[Flow injection biamperometric analysis of isoniazid].

AIM: To establish a simple, rapid, and accurate electrochemical method for on-line determination of isoniazid. METHODS: Based on the flow injection biamperometry for irreversible couple system, and using two preanodized platinum electrodes with the applied potential difference of 0 V, the biamperometric method for the determination of isoniazid has been proposed by coupling the catalytic oxidation of isoniazid and the reduction of platinum oxide. RESULTS: Common excipients, inorganic ions, amino acids, vitamins and proteins do not interfere with the determination. Linear relationship between current and the concentration of isoniazid is obtained in the range of 1.0 x 10(-6)-1.0 x 10(-4) mol.L-1 (gamma = 0.998, n = 11). The RSD of 1.8% was obtained for 8 successive determinations of 1.0 x 10(-5) mol.L-1 isoniazid. CONCLUSION: The proposed method has been shown to be sensitive, selective, rapid (120 samples.h-1), and suitable for the on-line direct determination of isoniazid.

Antitubercular Agents↗
PubMed2001

[Study of Newcastle disease virus in the treatment of human laryngeal squamous carcinoma].

OBJECTIVE: To explore the biological value of newcastle disease virus in the therapy of human laryngocarcinoma. METHODS: Nude mice model bearing laryngocarcinoma were established using human laryngeal squamous carcinoma cell line (Hep-2). Large amounts of Newcastle disease virus(NDV) were injected into the tumor. Changes in carcinoma administrated with the NDV were observed under light and electron microscopes. Isolation of NDV was attempted and sera were examined using the method of enzyme-linked immunosorbent assay (ELISA). RESULTS: The difference between experimental and control groups was statistically significant, including the average weight of the mice: t' = 2.397 (P < 0.05), the average weight of the tumor tissue: t' = 2.852 (P < 0.05) and the average volume of the tumor tissue: t' = 6.058 (P < 0.01). In the experimental group, the NDV was isolated in the tumor tissue and ELISA was positive. The necrosis of the tumor cell and inflammatory cellular infiltration were found under light and electron microscopes. CONCLUSION: These results indicated that NDV was effective in the treatment of laryngocarcinoma and had no damage to normal tissue.

Animals↗
PubMed2000

Simultaneous evanescent wave imaging of insulin vesicle membrane and cargo during a single exocytotic event.

The classical model of secretory vesicle recycling after exocytosis involves the retrieval of membrane (the omega figure) at a different site. An alternative model involves secretory vesicles transiently fusing with the plasma membrane (the 'kiss and run' mechanism) [1,2]. No continuous observation of the fate of a single secretory vesicle after exocytosis has been made to date. To study the dynamics of fusion immediately following exocytosis of insulin-containing vesicles, enhanced green fluorescent protein (EGFP) fused to the vesicle membrane protein phogrin [3] was delivered to the secretory vesicle membrane of INS-1 beta-cells using an adenoviral vector. The behaviour of the vesicle membrane during single exocytotic events was then examined using evanescent wave microscopy [4-6]. In unstimulated cells, secretory vesicles showed only slow Brownian movement. After a depolarizing pulse, most vesicles showed a small decrease in phogrin-EGFP fluorescence, and some moved laterally over the plasma membrane for approximately 1 microm. In contrast, secretory vesicles loaded with acridine orange all showed a transient (33-100 ms) increase in fluorescence intensity followed by rapid disappearance. Simultaneous observations of phogrin-EGFP and acridine orange indicated that the decrease in EGFP fluorescence occurred at the time of the acridine orange release, and that the lateral movement of EGFP-expressing vesicles occurred after this. Post-exocytotic retrieval of the vesicle membrane in INS-1 cells is thus slow, and can involve the movement of empty vesicles under the plasma membrane ('kiss and glide').

Acridine Orange↗
PubMed2000

A novel method for measurement of submembrane ATP concentration.

There has been considerable debate as to whether adenosine triphosphate (ATP) is compartmentalized within cells and, in particular, whether the ATP concentration directly beneath the plasma membrane, experienced by membrane proteins, is the same as that of the bulk cytoplasm. This issue has been difficult to address because there is no indicator of cytosolic ATP, such as those available for Ca(2+), capable of resolving the submembrane ATP concentration ([ATP](sm)) in real time within a single cell. We show here that mutant ATP-sensitive K(+) channels can be used to measure [ATP](sm) by comparing the increase in current amplitude on patch excision with the ATP dose-response curve. In Xenopus oocytes, [ATP](sm) was 4.6 +/- 0.3 mm (n = 29) under resting conditions, slightly higher than that measured for the bulk cytoplasm (2.3 mm). In mammalian (COSm6) cells, [ATP](sm) was slightly lower and averaged 1.4 +/- 0.1 mm (n = 66). Metabolic poisoning (10 min of 3 mm azide) produced a significant fall in [ATP](sm) in both types of cells: to 1.2 +/- 0.1 mm (n = 24) in oocytes and 0.8 +/- 0.11 mm for COSm6 cells. We conclude that [ATP](sm) lies in the low millimolar range and that there is no gradient between bulk cytosolic and submembrane [ATP].

Adenosine Triphosphate↗
PubMed2000

alpha-fluoromethylhistidine depletes histamine from secreting but not from non-secreting rat stomach ECL cells.

Histamine in the oxyntic mucosa of the rat stomach occurs in mast cells (10%) and ECL cells (90%). Unlike the mast cells, the ECL cells operate under the control of gastrin. alpha-Fluoromethylhistidine, an irreversible inhibitor of the histamine-forming enzyme, histidine decarboxylase depletes ECL-cell but not mast-cell histamine. This report shows that the effectiveness by which histidine decarboxylase inhibition depletes ECL-cell histamine depends on the rate of histamine secretion. Rats received alpha-fluoromethylhistidine by continuous subcutaneous infusion for 24 h. Maximally effective doses (>/=3 mg/kg/h) inhibited histidine decarboxylase and reduced oxyntic mucosal histamine in fed rats by 80-90%. In fasted rats, the reduction was 50%. alpha-Fluoromethylhistidine greatly reduced the number of histamine-immunoreactive ECL cells (immunocytochemistry) and of secretory vesicles in the ECL cells (electron microscopy) in fed but not in fasted rats. The half-life of oxyntic mucosal histamine (determined upon histidine decarboxylase inhibition) was 2.6 h in fed rats and 19.4 h in fasted rats. The amount of histamine secreted in response to gastrin (monitored by gastric submucosal microdialysis) was greatly reduced by alpha-fluoromethylhistidine in fed rats but not in fasted rats. ECL cells were isolated from rat stomach by elutriation (80% purity). Their histamine content was determined after culture, with or without alpha-fluoromethylhistidine, in the presence of varying concentrations of gastrin. In a medium containing 10 nM gastrin, ECL cells responded to a maximally effective concentration of alpha-fluoromethylhistidine (0.1 nM) with 80% reduction in histamine content. In the absence of gastrin, ECL cells responded to alpha-fluoromethylhistidine with 45% reduction of histamine; the releasable histamine pool was unaffected. In conclusion, the combination of histidine decarboxylase inhibition and a high rate of histamine secretion will promptly exhaust the ECL-cell histamine pool, while histidine decarboxylase inhibition and a low secretion rate will affect the histamine pool much less.

Animals↗
PubMed2000

Expression profiling of pancreatic beta cells: glucose regulation of secretory and metabolic pathway genes.

Pancreatic beta cells respond to changes in blood glucose by secreting insulin and increasing insulin synthesis. To identify genes used in these responses, we have carried out expression profiling of beta cells exposed to high (25 mM) or low (5.5 mM) glucose by using oligonucleotide microarrays. Functional clustering of genes that averaged a 2.2-fold or greater change revealed large groups of secretory pathway components, enzymes of intermediary metabolism, cell-signaling components, and transcription factors. Many secretory pathway genes were up-regulated in high glucose, including seven members of the endoplasmic reticulum (ER) translocon. In agreement with array analysis, protein levels of translocon components were increased by high glucose. Most dramatically, the alpha subunit of the signal recognition particle receptor was increased over 20-fold. These data indicate that the translocon and ribosome docking are major regulatory targets of glucose in the beta cell. Analysis of genes encoding enzymes of intermediary metabolism indicated that low glucose brought about greater utilization of amino acids as an energy source. This conclusion was supported by observations of increased urea production under low-glucose conditions. The above results demonstrate genome-wide integration of beta-cell functions at the level of transcript abundance and validate the efficacy of expression profiling in identifying genes involved in the beta-cell glucose response.

Animals↗
PubMed2000

Ornithine decarboxylase activity and its gene expression are increased in benign hyperplastic prostate.

BACKGROUND: Ornithine decarboxylase (ODC) is the first key enzyme in the polyamine biosynthesis pathway. Polyamine is believed to participate in cellular proliferation and differentiation. To study the relationship between ODC and the pathogenesis of benign prostatic hyperplasia (BPH), the polyamine levels, ODC activities, and expression of ODC mRNA in benign hyperplastic and normal human prostates were assayed. METHODS: Polyamine contents and ODC activities in tissue extracts were determined by reverse-phase high-performance liquid chromatography and spectrophotometric procedures, respectively. The ODC mRNA levels were assayed by Northern blot analysis. RESULTS: The contents of putrescine, spermidine, and spermine in BPH tissues were 2.2, 3.4, and 6.0 times higher than those in normal tissues, respectively; the ODC activity of BPH tissue was about 3.2 times higher than in normal tissue; the expression level of ODC mRNA in the BPH tissues was greater than that of normal tissues. CONCLUSIONS: The findings imply that 1) the increased ODC activity and polyamine content in prostatic tissue may correlate with the pathogenesis of BPH, and 2) the high level of ODC activity is induced by the overexpression of ODC mRNA.

Adult↗
PubMed2000

The effect of knot location, suture material, and suture size on the gliding resistance of flexor tendons.

The effect of knot location, suture material, and suture size on gliding resistance between the pulley and flexor tendon was investigated in a canine model. Different suture materials [monofilament nylon (Ethilon), braided polyester suture coated with silicone (Ticron) and uncoated braided polyester suture (Mersilene)] and suture sizes (4-0, 5-0) were tested. A knot was made on either the volar surface, on one lateral side, or on both lateral sides of canine hind-paw tendons, and gliding resistance was measured. In addition, the frictional coefficient between three suture materials (4-0 nylon, 4-0 Ticron, 4-0 Mersilene) and a nylon rod were measured. The gliding resistance of the tendon with knots on both sides was highest, while tendons with one lateral knot had the lowest resistance (p < 0.01). The gliding resistance of 4-0 suture size was higher than that of 5-0 size (p < 0.0001). The coefficient of friction of nylon was lower than that of braided polyester suture (Ticron or Mersilene) (p < 0.001). The placement of knots and choice of suture material affect gliding resistance after tendon repair, and may, therefore, have an effect on the result of tendon repair.

Animals↗
PubMed2000

Dna adducts, mutations, and cancer 2000.

The main achievements in the DNA adduct field in the 1990s have been technical innovations of methods for specific adducts reaching sensitivities required for low levels encountered in humans. Over 20 specific adducts or closely related groups of adducts have been determined in humans. The sources of the DNA-binding agents are endogenous and exogenous or both. In some of these studies adduct levels have been correlated to metabolic or DNA repair genotypes. An example of DNA adduct studies in human target tissue is taken on UV photoproducts in skin in situ. Adduct-induced mutations, specific mutation spectra, and their relationship to cancer are discussed. The quantitative adduct techniques will enable comparisons of endogenous and exogenous adduct levels and will give important clues to the etiology of human cancer. Furthermore, adducts will provide an intermediary tool for genotyping studies, both for metabolic enzyme and for DNA repair system genotypes. As the common polymorphisms are likely to cause at most moderate increases in the risk of cancer, the intermediary adduct endpoint is a necessary proof of causal relationships. The present and future biomonitoring studies will cover many endpoints to link the mechanistic steps from DNA adducts to cancer via mutations and modulating host susceptibility factors.

Animals↗
PubMed2000

Two cases of ectopic hamartomatous thymoma.

Ectopic hamartomatous thymoma (EHT) is a rare benign neoplasm. Since it was named by Rosai et al. in 1984, 24 cases have been reported. We herein report two cases of EHT, one of which presented with massive myoid cells, and review the literature related to EHT. Both of our cases displayed the typical features of EHT: (1) nests of epithelial cells, including solid, cystic, or glandular epithelial islands; (2) spindle cells dominating the microscopic picture; and (3) adipose cells which intermingle haphazardly to impart a hamartomatous quality to the tumor. In this paper, we observed massive myoid cells and the transition from spindle epithelial cell to myoid cell in one of our cases. Immunohistochemical examinations showed that the main component of EHT, spindle cells, was positive for cytokeratin and epithelial membrane antigen (EMA). Intriguingly, the myoid cells simultaneously expressed cytokeratin, EMA, myoglobin, and creatine kinase-mm, suggesting that myoid cells may originate from epithelial cells and are an intermediate state between epithelial cells and muscular cells.

Adipocytes↗
PubMed2000

Solubilization of substituted indole compounds by beta-cyclodextrin in water.

The solubilization of four pairs of substituted indole compounds (SICs) by beta-cyclodextrin (beta-CD) in water was investigated. The results show that 1,2,3,4-tetrahydrocarbazole and N-methyl-1,2,3,4-tetrahydrocarbazole form 1:1 inclusion complexes with beta-CD, while the other six SICs form 1:2 inclusion complexes, respectively. To each pair of SICs with similar structures, the differences between their solubilization in beta-CD/water solutions has been explained by the difference of their contact area within the beta-CD cavity, the difference of their molecule polarity, or the presence of hydrogen bond between SIC molecule and beta-CD molecule.

Carbazoles↗
PubMed2000

Individual variability of dopamine release from nucleus accumbens induced by nicotine.

Effects of subcutaneous administration of vehicle, amphetamine (1 mg/kg) or nicotine (0.4 mg/kg, injected twice, 90 min apart) on extracellular dopamine (DA) concentration in the nucleus accumbens (ACC) and ventral tegmental area (VTA) of the Sprague-Dawley rat were studied using microdialysis. Experiments were conducted at least 10 days following implantation of guide cannulae, and at least 2 h following insertion of microdialysis probes into the guides on the morning of each experiment. Probes were perfused at 2.5 microl/min and several fractions were collected every 10 min before and after the two test injections. Samples were analyzed by high-performance liquid chromatography with electrochemical detection for the major neurotransmitters and their metabolites. Significant DA release following nicotine administration was observed in ACC but not in VTA. By classifying ACC DA responses of individual rats, three major subgroups were identified which exhibited more robust responses. Nicotine appeared to be acting as a modulator of ACC DA, increasing DA output if baseline was <5 nM, but slowing release when the baseline exceeded 5 nM. These data are consistent with previous reports of modulation of arousal level by nicotine via DA.

Animals↗
PubMed2000

Plant proteolytic enzymes: possible roles during programmed cell death.

Proteolytic enzymes are known to be associated with developmentally programmed cell death during organ senescence and tracheary element differentiation. Recent evidence also links proteinases with some types of pathogen- and stress-induced cell suicide. The precise roles of proteinases in these and other plant programmed cell death processes are not understood, however. To provide a framework for consideration of the importance of proteinases during plant cell suicide, characteristics of the best-known proteinases from plants including subtilisin-type and papain-type enzymes, phytepsins, metalloproteinases and the 26S proteasome are summarized. Examples of serine, cysteine, aspartic, metallo- and threonine proteinases linked to animal programmed cell death are cited and the potential for plant proteinases to act as mediators of signal transduction and as effectors of programmed cell death is discussed.

Apoptosis↗
PubMed2000

Post-earthquake quality of life and psychological well-being: longitudinal evaluation in a rural community sample in northern China.

This study aims to observe longitudinal change of quality of life (QOL) and psychological well-being in a community sample affected by an earthquake and to examine the relationship between QOL and disaster exposure, post-disaster support and other related variables. The subjects, from two villages at different distances from the epicenter, were assessed using the brief version of the World Health Organization Quality of Life Assessment (WHOQOL-BREF) and three subscales of a symptoms checklist at 3 months (n=335) and 9 months (n=253) after the earthquake, respectively. Exposure to the earthquake was associated with multidimensional impairment in QOL, including physical, psychological and environmental domains at 3 months, and psychological and environmental domains at 9 months. The victims also suffered significantly more psychological distress in terms of depression, somatization and anxiety. At both assessment points the group that experienced lower initial exposure but then received less post-disaster help reported poorer QOL and psychological well-being. The two victim groups also differed significantly in changing trend along time. The group that received more support showed a general improvement in post-disaster well-being from 3 months to 9 months. The results confirm that post-disaster variables could be as important to post-disaster psychosocial outcomes as variables of pre-disaster vulnerability and disaster per se. A comprehensive and prospective assessment of disaster effects is imperative for the better organization of disaster relief programs and psychosocial interventions.

Adolescent↗
PubMed2000

Human DNA adducts of 1,3-butadiene, an important environmental carcinogen.

The N-1-(2,3,4-trihydroxybutyl)adenine (N-1-THB-Ade) adducts induced by 1,3-butadiene (BD) were analysed from lymphocytes of 15 workers occupationally exposed to BD and 11 controls by (32)P-post-labelling using HPLC with radioactivity detection. The difference in the adduct levels between the BD-exposed workers (4.5 +/- 7.7 adducts/10(9) nucleotides) and the controls (0.8 +/- 1.2 adducts/10(9) nucleotides) was statistically significant (Wilcoxon rank sum test, P = 0.038). This study shows for the first time BD-induced DNA adducts in humans and suggests that N-1-THB-Ade adducts may be used to biomonitor human exposure to BD.

Adult↗
PubMed2000

Exploiting secondary growth in Arabidopsis. Construction of xylem and bark cDNA libraries and cloning of three xylem endopeptidases.

The root-hypocotyl of Arabidopsis produces a relatively large amount of secondary vascular tissue when senescence is delayed by the removal of inflorescences, and plants are grown at low population density. Peptidase zymograms prepared from isolated xylem and phloem revealed the existence of distinct proteolytic enzyme profiles within these tissues. cDNA libraries were constructed from isolated xylem and bark of the root-hypocotyl and screened for cDNAs coding for cysteine, serine, and aspartic peptidases. Three cDNAs, two putative papain-type cysteine peptidases (XCP1 and XCP2) and one putative subtilisin-type serine peptidase (XSP1), were identified from the xylem library for further analysis. Using RNA gel blots it was determined that these peptidases were expressed in the xylem and not in the bark. Quantitative reverse transcriptase-polymerase chain reaction confirmed the RNA gel-blot results and revealed high levels of XCP1 and XCP2 mRNA in stems and flowers of the infloresence. A poly-histidine-tagged version of XCP1 was purified from Escherichia coli by denaturing metal-chelate chromatography. Following renaturation, the 40-kD recombinant XCP1 was not proteolytically active. Activation was achieved by incubation of recombinant XCP1 at pH 5.5 and was dependent on proteolytic processing of the 40-kD inactive polypeptide to a 26-kD active peptidase.

Amino Acid Sequence↗