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Biomedical subjects

C Han

Publications and source records attributed to C Han.

At least 91 records · Page 5Linked to original sources
PubMed1999

[A study on the reserve capacity of endothelial tissue plasminogen activator in patients with acute coronary syndrome].

OBJECTIVE: To study the changes of the endothelial tissue plasminogen activator (tPA) reserve capacity in patients with acute coronary syndromes (ACS). METHODS: Veinous blood was sampled for determination of markers of the fibrinolytic system and hypercoagulability at admission and on the 10th day in patients with acute coronary syndrome (ACS), including acute myocardial infarction (AMI) in 15 and unstable angina pectoris (UAP) in 20. An occlusion test to determine the maximal endothelial tPA release was performed in order to evaluate the endothelial tPA reserve capacity. 20 patients with stable angina pectoris (SAP) and 12 normal subjects served as control. RESULTS: Patients with ACS had higher levels of tPA mass concentration, PAI-1 activity, D-dimers mass concentration and TAT mass concentration at admission and on the 10th day as compared with those in SAP and normal subjects. Maximal endothelial tPA release was initially reduced to (2.2 +/- 0.8) microg/L (P < 0.01, vs patients with SAP), but the levels recovered on the 10th day of follow-up to (4.5 +/- 1.2) microg/L (P > 0.05, vs patients with SAP). CONCLUSION: Endothelial tPA reserve capacity is reduced only during the acute phase and becomes normalized during follow-up. The alterations of plasma markers of systemic fibrinolysis persist longer in patients with ACS. The results demonstrated that the intravascular thrombus formation may relate more to the disturbance of endothelial fibrinolysis than to markers of the systemic fibrinolytic system. It is very important to correct the disturbances of endothelial fibrinolysis during the acute phase of ACS.

Acute Disease↗
PubMed1999

[Experimental studies on the cancer chemoprevention of tea pigments].

A batch of short-term tests were used to examine the effects of tea pigments on three stages of carcinogenesis, i.e. initiation, promotion and progression. Forward gene mutation test and micronuclei test were used to study the initiation stage of carcinogenesis; metabolic cooperation test and mice ear test to study the promotion stage. Viability and growth ability of Hela cells in soft agar and S180 solid tumor test in mice were used to examine the effect of tea pigments on the third stage of carcinogenesis. The results showed that both tea pigments and tea polyphenols had significantly protective effects on initiation, promotion and progression stages in carcinogenesis. In vitro study showed that tea pigments and tea polyphenols could induce QR and GST activity in Hep G2 cells. Oral administration of 0.1% tea polyphenols and 0.1% tea pigments could increase GST activity in rat liver by 25% and 18% respectively, and this increase was accompanied by the significant increase of GST 1-1, 1-2 and 3-3 protein expression level in rat liver. Our results suggested that the anticancer effect of tea pigments was the same as that of tea polyphenols, and the anticancer properties of tea pigments might be mediated by activating the enzymes such as QR and GST, which play important roles in the detoxification and exclusion of carcinogen.

3T3 Cells↗
PubMed1999

[Molecular cloning of rat OB gene and its expression in Escherichia coli].

In order to provide rat OB gene product for studying the relationship between obesity and noninfectious diseases, rat OB cDNA was amplified by RT-PCR technique. 460 bp fragment of OB cDNA was subcloned into EcoRI/BamHI site of plasmid pUC 19. Sequence analysis of OB cDNA revealed that the translation reading frame was identical with that reported in the literature. Thereby plasmid pBV220-rOB was constructed and the specific expression of OB gene in E. coli identified by SDS-PAGE electrophoresis was obtained.

Amino Acid Sequence↗
PubMed1999

[Experimental study on anti-oxygen and promoting intelligence development of Codonopsis lanceolata in old mice].

The water labyrinth test and determining lipid peroxide (LPO) contents were used to assay the effects of Codonopsis lanceolata on promoting intelligence development and lipid peroxide. The results showed that latent period of old mice in water labyrinth was statistically shorten and the number of mistake of old mice was visibly reduced by drinking extraction of Codonopsis lanceolate 4 g/kg and 8 g/kg. These indicated that mice drinking extraction of Codonopsis lanceloata learned faster that those of drinking water. The contents of LPO in red blood cell and brain of mice and rate drinking extraction of Codonopsis lanceolata were significantly reduced, the activities of superoxide dismutase (SOD) in serum of rat drinking extraction of Codonopsis lanceolata were visibly increased. These presents that the extraction of Codonopsis lanceolata has the role of promoting learning and memory of old animal, its mechanism might be increasing SOD activity and decreasing LPO level.

Animals↗
PubMed1999

[Monitoring glucoamylase fermentation with infrared spectroscopy].

The glucoamylase fermentation was investigated with Fourier transform infrared spectroscopy. During the cultivation, the variation of carbon and nitrogen source can be reflected from the infrared spectra. In most cases, the complex media are used to cultivate cells or bacteria. It is difficult to construct calibration samples with synthetic mixtures which can represent the composition of real broth. The infrared spectral data of the real broth and off-line chemical analysis results were used to establish the calibration model. The model is successfully used to predict the concentrations of total sugar, reduced sugar, and nitrogen in real broth. The correlation coefficients between the infrared analysis results and chemical analysis are 0.999, 0.990 and 0.974 for total sugar, reduced sugar and nitrogen, respectively. The bacteria, culture and operating condition are relatively stable during the practical productive processes. The method can be used to monitor the industrial processes.

Aspergillus niger↗
PubMed1998

Mechanisms of stretch-induced changes in [Ca2+]i in rat atrial myocytes: role of increased troponin C affinity and stretch-activated ion channels.

To study the effects of stretch on the function of rat left atrium, we recorded contraction force, calcium transients, and intracellular action potentials (APs) during stretch manipulations. The stretch of the atrium was controlled by intra-atrial pressure. The Frank-Starling behavior of the atrium was manifested as a biphasic increase of the contraction force after increasing the stretch level. The development of the contraction force after step increase of the stretch (intra-atrial pressure from 1 to 3 mm Hg) was accompanied by the increase in the amplitude of the calcium transients (P<0.05, n=4) and decrease in the time constant of the Ca2+ transient decay. The APs of the individual myocytes were also affected by stretch; the duration of the AP was decreased at positive voltages (AP duration at 15% repolarization level, P<0.001; n=13) and increased at negative voltages (AP duration at 90% repolarization level, P<0. 01; n=13). To study the mechanisms causing these changes we developed a mathematical model describing [Ca2+]i and electrical behavior of single rat atrial myocytes. Stretch was simulated in the model by increasing the troponin (TnC) sensitivity and/or applying a stretch-activated (SA) calcium influx. We mimicked the Ca2+ influx by introducing a nonselective cationic conductance, the SA channels, into the membrane. Neither of the 2 plausible mechanosensors (TnC or SA channels) alone could produce similar changes in the Ca2+ transients or APs as seen in the experiments. The model simulated the effects of stretch seen in experiments best when both the TnC affinity and the SA conductance activation were applied simultaneously. The SA channel activation led to gradual augmentation of Ca2+ transients, which modulated the APs through increased Na+/Ca2+-exchanger inward current. The role of TnC affinity change was to modulate the Ca2+ transients, stabilize the diastolic [Ca2+]i, and presumably to produce the immediate increase of the contraction force after stretch seen in experiments. Furthermore, we found that the same mechanism that caused the normal physiological responses to stretch could also generate arrhythmogenic afterpotentials at high stretch levels in the model.

Action Potentials↗
PubMed1998

[Induction of NAD(P)H: quinone reductase by anticarcinogenic ingredients of tea].

By assaying the activity of NAD(P)H: quinone reductase (QR) in Hep G2 cells exposed to inducing agents, a variety of ingredients in tea, we compared their abilities on inducing QR and preventing cancer. The results showed that tea polyphenols, tea pigments and mixed tea were all able to induce the activity of QR significantly. The single-component ingredients of tea polyphenols and tea pigments, including thearubigens, EGCG and ECG, also enhanced the activity of QR. But EGC, EC, theaflavins, tea polysaccharide and tea caffeine, showed no apparent induction of QR. We found that among those tea ingredients studied, the multi-component ingredients were more effective than the single-component ones. So we thought that the abilities of antioxidation and cancer prevention of tea depended on the combined effects of several kinds of active ingredients, which mainly include tea polyphenols and tea pigments.

Animals↗
PubMed1998

Alteration of alpha1-adrenoceptor subtypes in aortas of 12-month-old spontaneously hypertensive rats.

Alterations in alpha1-adrenoceptor subtypes in aortas from 12-month-old spontaneously hypertensive rats (SHR) were studied in functional studies and RNase protection assays. The norepinephrine-induced contraction, including maximum response and pD2 values, was not significantly different between the SHR and age-matched Kyoto Wistar (WKY) rats. The pA2 values of the alpha1D-adrenoceptor subtype-selective antagonist BMY7378 (8-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-8-azaspiro(4.5)dec ane-7,9-dionedihydrochloride) were increased from 8.10 +/- 0.12 in WKY rats to 8.45 +/- 0.13 in SHR (P < 0.05). The pA2 values of the alpha1A-adrenoceptor subtype-selective antagonist RS-17053 (N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dim ethyl-1H-indole-3-ethanamine hydrochloride) were reduced from 8.52 +/- 0.20 in WKY rats to 7.82 +/- 0.18 in SHR (P < 0.05), whereas the pA2 values of the alpha1A/alpha1D-adrenoceptor subtype-selective antagonist WB4101 (2-(2,6-dimethoxphenoxyethyl)-aminomethyl-1,4 benzodioxane) were not significantly different between WKY rats and SHR (9.05 +/- 0.22 versus 9.27 +/- 0.15, P > 0.05). Preincubation of preparations in 50 microM chloroethylclonidine for 30 min irreversibly inhibited the norepinephrine-induced response more profoundly in aortas from SHR than in aortas from WKY rats. The results of RNase protection assays showed that mRNAs for alpha1A- and alpha1B-adrenoceptor subtypes were decreased and that mRNA for the alpha1D-adrenoceptor subtype was increased in aortas from SHR compared with WKY rats. The results suggested that the alpha1A-adrenoceptor subtype was decreased and the alpha1D-adrenoceptor subtype was increased in aortas of 12-month-old SHR.

Adrenergic alpha-Antagonists↗
PubMed1998

Effects of micromolar concentrations of Mn, Mo, and Si on alpha1-adrenoceptor-mediated contraction in porcine coronary artery.

We studied the effects of trace elements, Mn, Mo, and Si, on vasoconstriction induced by norepinephrine (NE) or electrical field stimulation in isolated porcine right coronary arteries. Alpha1-adrenoceptor (AR) antagonist prazosin dose-despondently suppressed vasoconstriction in response to NE or field stimulation indicating an alpha1-AR mediated response. Mn, Mo, and Si at 0.3-3 micromol/L dose-despondently inhibited NE mediated contraction (all p < 0.05). In contrast, Mn, Mo, and Si at the same concentrations (0.3-3 micromol/L) enhanced the maximal contractile response to field stimulation in a dose-dependent manner (all p < 0.05), but these elements at 10 micromol/L suppressed the vasoconstrictive response. The results indicate that in porcine right coronary arteries, the alpha1-AR-mediated vasoconstriction by NE or electrical field stimulation was affected differently by micromolar concentrations of Mn, Mo, and Si and that the elements might facilitate NE release presynaptically but inhibit the contractile response postsynaptically.

Adrenergic alpha-Antagonists↗
PubMed1998

Ca2+-dependence of vasoconstriction mediated by alpha1A-adrenoceptors in perfused rat hindlimb: a pharmacological approach.

We investigated the source of Ca2+ for the vasoconstriction mediated by alpha1a-adrenoceptors in perfused rat hindlimb in functional studies. The noradrenaline (NA)-induced maximum response was decreased by 92% following perfusion with Ca2+-free medium. Depletion of intracellular Ca2+-stores with repeatedly application of caffeine and NA in Ca2+-free medium resulted in complete abolishment of NA-response. Nifedipine concentration-dependently inhibited NA-contraction with a maximum inhibition of 65%. The residual nifedipine-insensitive response was further inhibited by Cd2+. Following depletion of Ca2+ stores with cyclopiazonic acid in Ca2+ free medium for 30 min, the NA-response obtained by re-admission of Ca2+ was decreased by 80%. However, re-introduction of Ca2+ to NA-treated tissues in Ca2+-free medium without prior treatment with cyclopiazonic acid normalizes the NA-response. These results suggest that the NA-contraction in this preparation is mediated largely via an influx of extracellular Ca2+, of which the majority utilizes L-type calcium channels. Only a small portion of the contractile response to NA is derived from intracellular stores, which probably also play a modulatory role on Ca2+ influx.

Animals↗
PubMed1998

Phase II study of liarozole in advanced non-small cell lung cancer.

The aim of this phase II study was to investigate the efficacy and tolerability of liarozole, a novel benzimidazole derivative, in non-small cell lung cancer (NSCLC). Liarozole 300 mg twice daily orally was evaluated in 14 patients with stage IIIB and IV NSCLC. 8 patients had received prior treatment with chemotherapy and/or radiotherapy. WHO toxicity grading and response criteria were used. Liarozole was well tolerated. Grade 2 toxicities included alopecia (1 patient), dermatological toxicity (5 patients), dry mouth (2 patients) and nausea and vomiting (2 patients). Leukocytosis was seen in 5 patients, including 2 cases with an elevated white cell count pretreatment. Liarozole was discontinued in 1 patient who developed intolerable progressive pruritus associated with an erythematous rash. No objective tumour response was seen, all 14 patients developing progressive disease within 4 months of commencing treatment. Liarozole was well tolerated but was ineffective as single agent therapy in the management of NSCLC. The side-effect profile was compatible with inhibition of retinoic acid degradation.

Administration, Oral↗
PubMed1998

Functional assessment of alpha 1-adrenoceptor subtypes in porcine coronary artery.

1. alpha 1-Adrenoceptors are known to play an important role in vasoconstriction in response to adrenergic stimulation. However, the functional importance of alpha 1-adrenoceptor subtypes at the epicardial coronary artery remains unclear. We examined alpha 1-adrenoceptor subtypes by comparing functional affinities for alpha-adrenoceptor antagonists on noradrenaline (NA)-induced vasoconstriction in porcine denuded right coronary arteries. 2. Noradrenaline induced a dose-dependent vasoconstriction in incubated vessel rings. Prazosin and phentolamine were potent and competitive antagonists for NA-induced contraction (pA2 10.27 and 9.03, respectively). In contrast, the selective alpha 2-adrenoceptor antagonist yohimbine had a low affinity (pA2 6.13). Two selective alpha 1A-adrenoceptor antagonists, WB 4101 and 5-methyl urapidil, were potent and competitive antagonists of alpha 1-adrenoceptor-induced contraction (pA2 10.67 and 8.90, respectively) and the selective alpha 1D-adrenoceptor antagonist BMY 7378 had a low affinity (pA2 6.06). Noradrenaline-induced contraction was insensitive to the alkylating effects of chlorethylclonidine. These observations indicate that the vasoconstriction is predominantly mediated by the alpha 1A-adrenoceptor subtype. This was also supported by a good correlation between pA2 values from the present study and reported binding affinities (pKi) of various alpha-adrenoceptor antagonists with cloned human alpha 1A-adrenoceptors (r = 0.98), but not for alpha 1B- or alpha 1D-adrenoceptor subtypes (r = 0.77 and 0.41, respectively). 3. Our results indicate that the alpha 1A-adrenoceptor is the main functional receptor subtype in porcine denuded coronary arteries.

Adrenergic alpha-Agonists↗
PubMed1998

[Relationship of serum trace elements to lung cancer and its clinical application].

The levels of serum trace elements Cu, Zn, Fe, Mn and Ca were measured by PE3030 atomic absorption spectrophotometer in 300 patients with lung cancer, 50 with nonmalignant pulmonary diseases and 100 healthy subjects. In addition, these trace elements were also measured in 60 cases with lung cancer (40 remitted, 20 non-remitted) before and after treatment. Results showed that the concentrations of serum Cu, Mn and Cu/Zn ratio were significantly higher (P < 0.01) but Zn, Ca were significantly lower (P < 0.05-0.01) in lung cancer and nonmalignant pulmonary diseases than in healthy controls. Within the three groups there has no difference among profession, area and age discovered. In the remitted patients with lung cancer, the levels of serum Cu and Cu/Zn ratio were significantly lower (P < 0.01) but Zn, Ca were significantly higher (P < 0.01) after treatment. In the non-remitted group, only Cu/Zn ratio was significantly higher (P < 0.01) after treatment. Multivariable logistic regression analysis showed that the Odds Ratio (OR) of serum Ca was 0.9950 with 95% Confidence interval (CI) 0.9910-0.9990, and the OR of Cu/Zn was 7.9914 with 95% CI 3.4310-18.6134. It was suggested that Ca might play a protective vole while Cu/Zn ratio a risk factor for lung cancer. Results also showed that if the threshold of Cu/Zn ratio set at 1.10 in the healthy control group, the positive rate of Cu/Zn ratio was 68% which might be important in diagnosis and to assessing the prognosis of lung cancer.

Adult↗
PubMed1998

[The antioxidative mechanisms of tea polyphenols in inhibiting tumor promotion by TPA].

In the mouse study, topical application of green tea polyphenols (GTP) significantly inhibited TPA-induced increasing of epidermal ornithine decarboxylase (ODC) and increased the activities of several antioxidant enzymes (CAT, GR and GST). In another in vitro study, when GTP was incubated with TPA and mice polymorphonuclear leukocytes (PMNs), TPA induced hydrogen peroxide formation was markedly suppressed with a dose-dependent relationship. The results suggest that the antioxidative effect of GTP may play an important role in inhibiting tumor promotion.

Animals↗
PubMed1998

[Short-term screening of anticarcinogenic ingredients of tea by cell biology assays].

By using a panel of short term cell biology assays, several ingredients of tea (tea pigments, caffeine, tea polysaccharide, tea polyphenols tablet and mixed tea) were screened in order to investigate their anticarcinogenic effects. The cytokinesis block micronuclei test in V79 cells induced by mitomycin, the test of metabolic cooperation between V79 and M cells and the test of growth ability of Hela cells in soft agar were used in the screening. The results showed that the six kinds of tea ingredients tested were effective in the test involved in different stages of carcinogenesis, i.e. initiation, promotion and progression. The effects of mixed tea and tea pigments were the strongest among the ingredients tested.

Animals↗
PubMed1998

[Study on the preventive effect of tea on DNA damage of the buccal mucosa cells in oral leukoplakias induce by cigarette smoking].

In order to study the preventive effect of tea on DNA damage induced by cigarette smoking and to provide further evidence on the protective effects of tea in human cancer, a 6-month, double-blind and randomized placebo-controlled intervention trial was carried out. The effect of tea on micronuclei frequency in exfoliated oral buccal mucosa cells in 36 oral leukoplakias of smokers was investigated. A kind of mixed tea given in an oral dose of 3 g/day and a concentration of 0.1% smeared on mucosa lession three times a day for 3 months and 6 months, significantly decreased the micronuclei formation in exfoliated oral buccal mucosa cells in subjects with oral leukoplakias. In contrast, there was no change in the micronuclei frequency after 6 months in the placebo group. The results indicate that mixed tea may reduce the oral cancer risk by preventing DNA damage in oral leukopiakias induced by cigarette smoking.

Adult↗
PubMed1998

[Effects of Curcuma phaeocaulis on learning and memory and lipid peroxide in mice].

Nine months mice were inoculated and the method of water maze test and lipid peroxide determination to study the effects of extract of Curcuma phaeocaulis Valeton on learning and memory ability and retarding of senescence. Results showed that in water maze test the time for the group with Curcuma phaeocaulis Valeton needed from initial position to the end was significantly shortened compared with old control. The error numbers for the group of Curcuma phaeocaulis Valeton were significantly decreased compared with old control after starting experiment for 18 days and 24 days and for 35 days no significance difference was showed between groups. The levels of brain, liver and red blood cells lipid peroxide in the group with Curcuma phaeocaulis Valeton were considerably lower than old control, hemoglobin content was considerably increased than old control.

Aging↗