Biomedical subjects

C Han

Publications and source records attributed to C Han.

At least 37 records · Page 2Linked to original sources

PubMed2001

VEGF-B expression in human primary breast cancers is associated with lymph node metastasis but not angiogenesis.

Angiogenesis is essential for tumour growth and metastasis. It is regulated by numerous angiogenic factors, one of the most important being vascular endothelial growth factor (VEGF). Recently VEGF-B, a new VEGF family member that binds to the tyrosine kinase receptor flt-1, has been identified. Although the importance of VEGF has been shown in many human tumour types, the contribution of VEGF-B to tumour neovascularization is unknown in any tumour type. This study therefore measured the mRNA level of VEGF-B and its receptor flt-1 by ribonuclease protection assay and the pattern of VEGF-B expression by immunohistochemistry in 13 normal breast samples and 68 invasive breast cancers. Flt-1 expression was significantly higher in tumours than in normal breast (p=0.02) but no significant difference was seen in VEGF-B between normal and neoplastic breast (p=0.3). There was a significant association between VEGF-B and node status (p=0.02) and the number of involved nodes (p=0.01), but not with age (p=0.7), size (p=0.6), oestrogen receptor (ER) (p=0.2), grade (p=0.5) or vascular invasion (p=0.16). No significant relationship was present between VEGF-B and flt-1 (p=0.2) or tumour vascularity (p=0.4). VEGF-B was expressed mostly in the cytoplasm of tumour cells, although occasional stromal components including fibroblasts and endothelial cells were also positive. No difference in VEGF-B expression was observed adjacent to regions of necrosis, in keeping with this VEGF family member not being hypoxically regulated. These findings suggest that VEGF-B may contribute to tumour progression by a non-angiogenic mechanism, possibly by increasing plasminogen activators and hence metastasis, as has been described in vitro. Measurement of VEGF-B together with other angiogenic factors may identify a poor prognostic patient group, which may benefit from anti-VEGF receptor therapy targeted to flt-1 (VEGFR1) as well as kdr (VEGFR2).

Adult↗

PubMed2001

High-throughput analysis in drug discovery: application of liquid chromatography/ion-trap mass spectrometry for simultaneous cassette analysis of alpha-1a antagonists and their metabolites in mouse plasma.

The application of liquid chromatography/ion-trap mass spectrometry for simultaneous quantification of multiple drugs and detection of their metabolites for in vitro experiments was reported recently. In the current study, the use of these techniques was extended to in vivo pharmacokinetic (PK) studies of alpha-1a antagonists. In combination with limited time-point PK, greatly increased throughput was demonstrated for the in vivo screening and investigation of in vivo-in vitro correlation. In addition to quantitative analyses, the technique allowed simultaneous detection of major in vivo metabolites without having to reanalyze the plasma samples. The drugs were individually dosed in mice intravenously via tail vein injection and the blood samples were collected 5 min and 2 h after dosing. After the plasma samples for the different drugs had been prepared separately, they were pooled for cassette analysis. The concentrations of five test compounds in the plasma samples at 2 h ranged from 36-1062 ng/mL, whereas their 5-min plasma levels were similar. From the same cassette analysis, major metabolites in the samples were also detected simultaneously through the interpretation of full-scan mass spectra. The metabolite identification confirmed the results from a previous report that the major sites of metabolism are hydroxylation of the phenyl ring not bearing the alkylsulfonamide substitutent, piperidine N-dealkylation, and N-demethylation of the alkylsulfonamide group.

Adrenergic alpha-Antagonists↗

PubMed2001

Identification of rice black-streaked dwarf fijivirus in maize with rough dwarf disease in China.

Three virus isolates from maize with rough dwarf in different provinces in China were analyzed at the molecular level. When compared to an isolate from diseased rice plants in Hubei Province, all four isolates had identical genomic RNA electrophoretic profiles, which were composed of ten double-stranded (ds) RNAs. Full-length cDNAs of segment 10 (S10) from each of the four isolates were cloned by RT-PCR and the complete sequences were determined. Analysis of the sequences revealed that each consisted of 1801 nucleotides and contained a single open reading frame (ORF) which potentially encoded a protein with 558 amino acids. Further, the sequences showed more than 97.0% and 98.0% identity at nucleotide and amino acid levels, respectively. In addition, their identities to rice black-streaked dwarf virus S10 were significantly higher than those to maize rough dwarf virus S10. Based on these results, it is suggested that the virus which causes this maize disease in China is rice black-streaked dwarf virus.

China↗

PubMed2001

Sexual and aggressive interactions in a visible burrow system with provisioned burrows.

The visible burrow system (VBS) is a habitat providing burrows and an open area for mixed-set rat colonies. Provisioning of food and water in the burrows makes it unnecessary for potentially defensive animals to leave the burrows to eat/drink on the surface, and enables evaluation of new types of agonistic interactions that may emerge when this necessity is removed. In such colonies, subordinate males showed high magnitude tunnel guarding behavior, occupying a tunnel opening onto the surface and confronting the dominant. Dominants, in response, made lunges into the tunnels, but quickly retreated without gaining entry, apparently stopped by contact with the defender's vibrissae. Dominants also made and continued to make lateral attacks to the wall adjacent to the tunnels guarded by subordinates, although these were useless in terms of affording contact with the subordinate. Dominant-female agonistic interactions were more frequent than those of dominants and subordinates. These were largely initiated by the male, and involved female defensive behavior. Nonetheless, females, unlike subordinates, failed to show tunnel guarding and continued to utilize the surface freely. They also spent more time in the vicinity of the dominant over days of colony formation. This apparent paradox may reflect that females were seldom wounded, and that the initial site of male contact with females was the female's anogenital area, findings suggesting that interactions of males and females often reflect male sexual advances, countered by female defenses that effectively protect nonestrus females from mounting and copulation.

Aggression↗

PubMed2001

Comparison of carotid vessel wall area measurements using three different contrast-weighted black blood MR imaging techniques.

Measuring carotid artery plaque burden from MRI is a reliable method for monitoring regression and progression of atherosclerosis. However, to measure all available images would be very time consuming, and in practice the image quality (IQ) of these images may be inconsistent, which can directly impact the quality of measurement. It is hypothesized that if IQ is comparable among different contrast weighted images, then carotid artery area measurements obtained from different contrast images of the same location will produce identical results. To test this, T1, proton density and T2 weighted images were acquired from ten patients (51 +/- 7 years old). Carotid lumen and vessel wall area was measured using a custom designed software program. The results showed strong agreement evidenced with only small differences on both lumen (mean: 40.5 mm(2)) and wall (mean: 52.6 mm(2)) area measurement among different weighted images. The maximum absolute mean differences are less than 2.7 mm(2) and 4.4 mm(2), and 90(th) percentile of the absolute differences are 5.6 mm(2) and 8.2 mm(2) respectively. In conclusion, different contrast weighted images with high and comparable IQ will yield similar results in lumen and vessel wall area measurement. At each matched location, it is recommended that the image with the highest IQ be used for area measurement.

Carotid Arteries↗

PubMed2001

In vivo drug target discovery: identifying the best targets from the genome.

A vast number of genes of unknown function threaten to clog drug discovery pipelines. To develop therapeutic products from novel genomic targets, it will be necessary to correlate biology with gene sequence information. Industrialized mouse reverse genetics is being used to determine gene function in the context of mammalian physiology and to identify the best targets for drug development.

Animals↗

PubMed2001

Effects of green tea on colonic aberrant crypt foci and proliferative indexes in rats.

The present study was designed to investigate the effect of green tea on 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) formation in Wistar rats. Forty-five male weanling Wistar rats were randomly divided into three groups. Rats in Group 1 were injected with DMH (20 mg/kg s.c.) once a week for 10 weeks. Animals in Group 2 received 2% green tea water extract as the sole source of drinking fluid in addition to the same treatment used for Group 1. Group 3 was the negative control group. Animals were killed at the end of Week 16 after the first DMH treatment. ACF were formed in animals in their DMH-treated groups at the end of Week 16. Group 2 had fewer ACF than Group 1. Compared with the positive control group, proliferating cell nuclear antigen labeling index, silver-stained nucleolar organizer regions, and ras-p21 expression were significantly reduced in Group 2. It was concluded that green tea drinking inhibited ACF formation in rats, and such effects may be related to the suppression of cell proliferation in the intestinal crypts.

1,2-Dimethylhydrazine↗

PubMed2001

Water acquisition and partitioning in Drosophila melanogaster: effects of selection for desiccation-resistance.

We examined physiological features related to water balance in five replicate populations of Drosophila melanogaster that have undergone selection for enhanced resistance to desiccation (D populations) and in five replicate control (C) populations. Adult D flies contain 34 % more water than the control flies. We examined two hypotheses for increased water acquisition in the D flies: (i) that they accumulate more water early in development and (ii) that they have a reduced post-eclosion diuretic water loss. We found no evidence of differential water or dry mass acquisition between the C and D populations prior to adulthood. We also found no evidence of differential post-eclosion diuresis, i.e. both C and D groups showed insignificant changes in water volume in the 4 h period immediately after eclosion. In addition, we quantified water content in the intra- and extracellular compartments of the C and D populations and were able to identify the hemolymph as the primary storage site of the 'extra' water carried by the desiccation-resistant flies. We estimated that 68 % of the increased water volume observed in the D flies was contained in the hemolymph. Desiccation-resistance was strongly correlated with hemolymph volume and only weakly with intracellular water volume. Survival during desiccation was also strongly related to the carbohydrate content of the D flies. It has been presumed that the D flies accumulate carbohydrate primarily as intracellular glycogen, which would result in a significant increase in intracellular water volume. We found that carbohydrate content was weakly correlated with intracellular water volume and more strongly with hemolymph volume. The carbohydrate pool in the D flies may, therefore, be contained in the extracellular compartment as well as in cells. These results are suggestive of the importance of modifications in hemolymph volume and hemolymph solute concentrations in the evolution of enhanced desiccation-tolerance in populations of Drosophila melanogaster.

Animals↗

PubMed2001

[Study on the inhibition of tea pigments on the adhesion between monocyte and endothelial cells].

In order to study the effects of tea pigments (TP) on the adhesion between monocyte and endothelial cells induced by oxidized low density lipoprotein(Ox-LDL), the fluorescence activated cell sorter (FACS) and the cell ELISA were applied. The results showed that TP could inhibit the adhesion between monocyte and endothelial cells(P < 0.05), and the expression of inter cell adhesion molecule(ICAM-1) and vascular cell adhesion molecule (VCAM-1) proteins in a dose dependent manner(P < 0.05). The results suggested that the inhibition of TP on ICAM-1 and VCAM-1 expression was one of the mechanisms of its antiadhesion between monocyte and vascular endothelial cells, as well as that of its antiatherosclerosis.

Cell Adhesion↗

PubMed2001

Angiopoietin-1 is inversely related to thymidine phosphorylase expression in human breast cancer, indicating a role in vascular remodeling.

PURPOSE: Angiogenesis is essential for tumor growth and metastasis. It is a complex, dynamic process that is coordinated by several classes of angiogenic factors. One candidate family is the Tie2 tyrosine kinase, whose expression is restricted largely to endothelial cells. Tie2 has three known ligands, angiopoietin (Ang)-1, Ang-2, and Ang-4, that have different functional effects but play a requisite role in embryonic vessel remodeling. Because there are only limited data on the Tie2 pathway in human breast cancer, and our previous data have suggested that breast tumors establish a blood supply by vascular remodeling, we have investigated the expression of Ang-1, Ang-2, Ang-4, and Tie2 in a series of normal and neoplastic human breast tissues. EXPERIMENTAL DESIGN: We examined mRNA expression by reverse transcription-PCR in 6 normal and 52 malignant breast tissues and correlated expression with clinicopathological and angiogenic variables. We also examined the effect of physiological levels of estrogen on Ang expression. RESULTS: Ang-1, Ang-2, Ang-4, and Tie2 were detected in 19%, 52%, 35%, and 65%, respectively, of tumor samples. There was a significant reduction in expression of tumor Ang-1 (P = 0.04), Ang-2 (P = 0.01), Ang-4 (P = 0.004), and Tie2 (P = 0.02) compared with that in normal breast tissues. There was a significant relationship in tumors between all Angs and between each ligand and Tie2. In a multivariate analysis, there were significant positive correlations between Ang-4 and estrogen receptor (P = 0.016) and a significant inverse correlation between Ang-1 and thymidine phosphorylase expression (P = 0.01). No significant associations were observed between the other members of the Ang/Tie2 gene family and patient age, tumor size, lymph node status, tumor grade, vascular invasion, tumor vascularity, vascular maturation, thymidine phosphorylase, or vascular endothelial growth factor A expression (P > 0.05 for all). The potential regulation of Ang-4 by estrogen was further investigated in vitro. Addition of physiological concentrations of 17beta-estradiol (1 nM) to hormone-free media caused no significant change in Ang-4 mRNA abundance (P = 0.75) in the estrogen receptor-positive cell line MCF-7 after either 2 or 18 h, despite demonstrating induction for the estrogen response gene pS2. CONCLUSIONS: These findings suggest that the Ang/Tie2 pathway plays a significant role in human breast tumor angiogenesis but provide no initial evidence for direct regulation of the pathway by estrogen.

Angiopoietin-1↗

PubMed2001

[Effects of yinchenhao decoction on normal animals and animal models of diabetes mellitus].

OBJECT: To study the effects of yinchenhao Decoction on the blood glucose level in a variety of animal models and its mechanism. METHODS: Normal mice, rats model of ailoxan (ALX)-induced diabetes mellitus (DM), mice model of ALX-DM and rats model of dexamethasone (DX)-induced insulin resistance (IR) were used. RESULTS: yinchenhao Decoction was able to inhibit the hyperglycemia by ALX-induced mice(P < 0.01), significantly reduce level of FBG in normal mice, ALX-DM mice and rats (P < 0.05-0.01), improve IGT and lower 2hBG (P < 0.01) after OGTT in DX-induced insulin-resistant rats. CONCLUSIONS: The results suggest that yinchenhao Decoction possesses similar hypoglycemic action to meftormin and gliclazied.

Animals↗

PubMed2001

[Treatment of the ocular burn with hormone].

OBJECTIVE: To explore new ways of the management of ocular burn with the use of hormones (human growth hormone and corticosteroid). METHODS: Twenty-one patients (30 eyes) with ocular burn were enrolled in the study. Nine cases (12 eyes) were treated with routine methods, while in 12 cases (18 eyes) corticosteroid and recombinant human growth hormone (rhGH) were used. The corticosteroid was applied immediately postburn both systemically and topically and continued for 2-4 weeks. But the rhGH was applied after 1 week postburn and continued for 2 weeks. The results in the above two groups were compared. RESULTS: Compared with those in control group, all the 18 eyes in the 12 patients with ocular burn were saved and cured with the treatments of hormones. There was significantly less incidence of corneal ulceration and perforation and better visual recovery in those treated with the hormones. CONCLUSION: Combined application of corticosteroid and rhGH might be beneficial to the management of patients with ocular burn.

Adrenal Cortex Hormones↗

PubMed2001

[Observation on the effect of disinfection to HBsAg by electrolyzed oxidizing water].

OBJECTIVE: Observation on the effect of disinfection on gastroscope, contaminated by hepatitis B surface antigen (HBsAg) in the electrolyzed oxidizing water (EOW). METHODS: Contaminated gastric juice and serum was added to EOW for 1 minute. Positive control samples were treated with PBS instead of EOW in the same way. Gastroscopes used for hepatitis patients were immersed in the EOW for 1 minute after cleaning. Samples were collected before and after treatment. ELISA was used to test HBsAg. RESULTS: With mixed samples (average S/N = 42.16) of EOW, HBsAg became negative when diluted in 100 times. However, the HBsAg of positive control samples remained positive. After cleaning the gastroscope (average S/N = 5.99) immersed in EOW, HBsAg became negative. CONCLUSION: EOW was effective in destroying HBsAg which could be used for gastroscope disinfection.

Disinfection↗

PubMed2001

[A study on mechanism for cytotoxicity of nitrobenzene to hepatocarcinoma cell line].

OBJECTIVE: To study the mechanism for cytotoxicity of nitrobenzene to hepatocarcinoma cell line. METHODS: Cytotoxicity was determined with MTT assay in SMMC-7721 cell strain, human hepatocarcinoma cell, incubated with nitrobenzene at varied concentrations in vitro for 24 hours. The effect of an agent to clear reactive oxygen on protection from cell death was observed. Cell cycle of hepatocytes was also observed using flow cytometry and their DNA damage was detected with single-cell gel electrophoresis assay. RESULTS: Nitrobenzene at concentration of 8 mmol/L or over could induce death of hepatocytes obviously with a survival rate of less than 82%, and addition of superoxide dismutase, hydrogen peroxidase or mannitol to the incubation media could inhibit its cytotoxicity partly, with survival rates of 93.7%, 96.6% and 93.2%, respectively. Nitrobenzene could affect cell cycle of hepatocytes, showing a decreased fraction of G(1) phase and increased fraction of S and G(2)/M phase, but could not induce DNA strand breaks in them. CONCLUSIONS: Nitrobenzene had cytotoxicity to hepatocytes cultured in vitro, in which reactive oxygen species may play a certain role. Nitrobenzene was a non-genotoxicant and could cause cancer by promotion of cell proliferation.

Cell Cycle↗

PubMed2001

[Studies on the inhibitory effects of tea polyphenols and tea pigments on liver precancerous lesion in rats].

The chemopreventive effects of tea polyphenols and tea pigments on liver precancerous lesion in rats were investigated. The results showed that the density and area of GST-P in the tea-treated groups were significantly reduced as compared with the positive control group. Furthermore, tea polyphenols and tea pigments induced the expression of p21WAF1 protein, inhibited the expression of Bcl-2 protein and induced the expression of Bax protein. It is concluded that GST-P was significantly inhibited by tea polyphenols and tea pigments and inhibition of cell proliferation and induction of apoptosis may be the two important mechanisms.

Animals↗

PubMed2001

[Auricular cartilage palisade technique for repairing tympanic membrane perforation].

OBJECTIVE: To study the auricular cartilage palisade technique for repairing tympanic membrane perforation. METHOD: Sixty-six cases of large tympanic membrane perforation were treated with auricular cartilage. The results were compared with that of temporal fascia repairing in 60 ears. RESULTS: The closure rates of tympanic membrane perforation were 92.4% in cartilage group and 80% in temporal fascia group, respectively. There was no significant difference between two groups in hearing improvement. The cartilage is quite suitable for repairing large perforation of the tympanic membrane and for treating adhesive otitis media. CONCLUSION: The auricular cartilage palisade technique is an ideal method for repairing tympanic membrane perforation.

Adult↗

PubMed2000

[Effect of tea polyphenols and tea pigments on inducing the activity of phase II detoxicating enzymes and on the chemoprevention of liver precancerous lesions].

In order to elucidate the chemoprevention mechanism of tea, the regulative effect of tea polyphenols and tea pigments on phase II enzyme, glutathions S-transferase (GST) activity and its isoenzymes in Wistar rat were studied. Rat liver precancerous lesions were initiated with diethylnitrosamine (DEN), promoted with partial hepatectomy and carbon tetrachloride. The rats were killed after 8 weeks of treatment. Liver cytosol GST activities were tested. The GST 1-1, 1-2, 3-3 and Pi isoenzymes were detected with Western Blot method. The results showed that the activities of GST increased greatly in the tea polyphenol and tea pigment groups, while the activities were decreased in positive control group. Both tea polyphenold and tea pigments increased the activities of classes GST alpha (GST1-1, 1-2) and GST mu(GST3-3). The increase of GST alpha was more in tea polyphenol group, and the increase of GST mu was more in tea pigment group. Both tea polyphenols and tea pigments inhibited the over expression of GST Pi in the rats treated with DEN/PH/CCl4. The study indicated that tea polyphenols and tea pigments modulated phase II enzymes effectively, thus inhibited the occurrence and development of the precancerous lesions of rat liver.

Animals↗

PubMed2000

Molecular cloning of a soybean class III beta-1,3-glucanase gene that is regulated both developmentally and in response to pathogen infection.

We isolated and characterized a soybean gene (SGN1) encoding a basic beta-1,3-glucanase that is a plant class III isoform of beta-1,3-glucanase. The deduced amino acid sequence of the SGN1 gene is similar to that of the PR-Q'b gene, the basic class III beta-1,3-glucanase of tomato. Based on RNA blot hybridization, SGN1 gene expression was detected in all tissues of 4-day old seedlings, but it was present only in root tissue of 30-day old plants. GUS expression analysis carried out in transgenic tobacco plants harboring a SGN1::GUS reporter gene revealed the same expression pattern. Furthermore, the expression of SGN1 was strongly induced by a variety of defense-related signals, such as treatment with H(2)O(2), wounding, or treatment with fungal elicitor prepared from Phytophthora spp as well as inoculation with Pseudomonas syringae. However, the expression level of SGN1 was hardly induced with jasmonate, ethephon and salicylate. Overall the results suggest that the SGN1 may play a role in both plant development and plant defense against pathogen attack.

Journal Article↗