Biomedical subjects

S Sun

Publications and source records attributed to S Sun.

At least 91 records · Page 5Linked to original sources

PubMed2000

International Quit and Win 1996: comparative evaluation study in China and Finland.

OBJECTIVES: To compare background and process variables, as well as follow up status, of the participants in the International Quit and Win '96 contests of China and Finland, and analyse factors contributing to sustained maintenance. DESIGN: A standardised 12 month follow up was conducted in both countries with random samples of participants. The sample sizes were 3119 in China and 1448 in Finland, with response rates of 91.2% and 65.2%, respectively. INTERVENTIONS: The International Quit and Win '96 contest was the second coordinated, multinational smoking cessation campaign targeted at adult daily smokers. Altogether 25 countries participated, including China with 15 000 and Finland with 6000 smokers registered. MAIN OUTCOME MEASURES: Conservative (considering all non-respondents relapsed) and non-conservative (based on respondents only) estimates were calculated for one month abstinence, 12 month continuous abstinence, and point abstinence at the time point of follow up. RESULTS: Great differences were found in the background and process variables, as well as in the outcome measures. At one year follow up, the conservative continuous abstinence rates show that the Chinese participants maintained their abstinence better (38%) compared to the Finnish ones (12%). In China women reached higher abstinence rate (50%) than men (36%), whereas in Finland men achieved a better result (14%) than women (9%). CONCLUSIONS: The Quit and Win contest is a mass smoking cessation method feasible in countries showing great variance in smoking habits and rates. However, in countries with different stages of anti-smoking development, such as China and Finland, different practical implementation strategies may be needed.

Adolescent↗

PubMed2000

K(ATP) channel activation reduces the severity of postresuscitation myocardial dysfunction.

Postresuscitation myocardial dysfunction has been recognized as a leading cause of the high postresuscitation mortality rate. We investigated the effects of ischemic preconditioning and activation of ATP-sensitive K(+) (K(ATP)) channels on postresuscitation myocardial function. Ventricular fibrillation (VF) was induced in 25 Sprague-Dawley rats. Cardiopulmonary resuscitation (CPR), including mechanical ventilation and precordial compression, was initiated after 4 min of untreated VF. Defibrillation was attempted after 6 min of CPR. The animals were randomized to five groups treated with 1) ischemic preconditioning, 2) K(ATP) channel opener, 3) ischemic preconditioning with K(ATP) channel blocker administered 1 min after VF, 4) K(ATP) channel blocker administered 45 min before induction of ischemic preconditioning, and 5) placebo. Postresuscitation myocardial function, as measured by the rate of left ventricular pressure increase at 40 mmHg, the rate of left ventricular decline, cardiac index, and duration of survival, was significantly improved in both preconditioned and K(ATP) channel opener-treated animals. K(ATP) channel blocker administered 45 min before induction of ischemic preconditioning completely abolished the myocardial protective effects of preconditioning. We conclude that ischemic preconditioning significantly improved post-CPR myocardial function and survival. These results also provide evidence that the myocardial protective effects of ischemic preconditioning are mediated by K(ATP) channel activation.

Adenosine Triphosphate↗

PubMed2000

Antitumor activity of astaxanthin and its mode of action.

Astaxanthin, a carotenoid without vitamin A activity, may exert antitumor activity through the enhancement of immune responses. Here, we determined the effects of dietary astaxanthin on tumor growth and tumor immunity against transplantable methylcholanthrene-induced fibrosarcoma (Meth-A tumor) cells. These tumor cells express a tumor antigen that induces T cell-mediated immune responses in syngenic mice. BALB/c mice were fed astaxanthin (0.02%, 40 micrograms/kg body wt/day in a beadlet form) mixed in a chemically defined diet starting zero, one, and three weeks before subcutaneous inoculation with tumor cells (3 x 10(5) cells, 2 times the minimal tumorigenic dose). Three weeks after inoculation, tumor size and weight were determined. We also determined cytotoxic T lymphocyte (CTL) activity and interferon-gamma (IFN-gamma) production by tumor-draining lymph node (TDLN) and spleen cells by restimulating cells with Meth-A tumor cells in culture. The astaxanthin-fed mice had significantly lower tumor size and weight than controls when supplementation was started one and three weeks before tumor inoculation. This antitumor activity was paralleled with higher CTL activity and IFN-gamma production by TDLN and spleen cells in the astaxanthin-fed mice. CTL activity by TDLN cells was highest in mice fed astaxanthin for three weeks before inoculation. When the astaxanthin-supplemented diet was started at the same time as tumor inoculation, none of these parameters were altered by dietary astaxanthin, except IFN-gamma production by spleen cells. Total serum astaxanthin concentrations were approximately 1.2 mumol/l when mice were fed astaxanthin (0.02%) for four weeks and appeared to increase in correlation with the length of astaxanthin supplementation. Our results indicate that dietary astaxanthin suppressed Meth-A tumor cell growth and stimulated immunity against Meth-A tumor antigen.

Adjuvants, Immunologic↗

PubMed2000

Atrial function during cardiac arrest caused by ventricular fibrillation.

OBJECTIVES: To report observations on preserved regular atrial electrical and mechanical systole during ventricular fibrillation (VF) and to quantitate blood flow generated by atrial contractions in this setting. METHODS: In 10 rats, right atrial pressure pulses were continuously recorded before and for an interval of 8 min after inducing VF. In 3 isolated, perfused rat hearts, epicardial right atrial electrograms were recorded after inducing VF. In 15 pigs, transesophageal echo-Doppler measurements were obtained with pulsed and color-Doppler visualization of flow across the mitral valve after onset of VF. RESULTS: In each rat, regular right atrial pressure pulses were documented during VF. These persisted over an average interval of 7.5 min. In isolated, perfused hearts, right atrial contractions were accompanied by regular atrial depolarizations. In pigs, regular atrial contractions generated atrial stroke volumes of approximately 12 mL, or 25% of prearrest values during the first minute after onset of VF, but those declined to approximately 6 mL after 10 min of untreated cardiac arrest. Blood flow from the left atrium into the left ventricle failed to advance significantly into the systemic circuit. During atrial diastole, we observed reversal of flow into the left atrium. CONCLUSIONS: Atrial contractions are preserved during the initial 8 min or more after cardiac arrest due to VF. Substantial forward flow into the left ventricle failed to advance through the outflow tract but regurgitated into the atrium during atrial diastole.

Animals↗

PubMed2000

Technology evaluation: SELEX, Gilead Sciences Inc.

Systematic evolution of ligands by exponential enrichment (SELEX) technology has been under development for a decade, and is a general method for identification of oligonucleotide ligands as potential drugs. A pool of randomized RNA or single stranded DNA sequences were selected against certain targets. The sequences of tighter binding with the targets were isolated and amplified. The selection was repeated using the enriched pool derived from the first round selection. Several rounds of this process lead to winning sequences that are called 'aptamers' or 'ligands'. This technology has been applied to a wide range of targets including various enzymes of HIV, growth factors and inflammation-inducing enzymes. The first aptamer that has proceeded to phase I clinical studies is NX-1838, an injectable angiogenesis inhibitor that can be potentially used to treat macular degeneration-induced blindness.

Animals↗

PubMed2000

Mechanism of free radicals on the molecular fluidity and chemical structure of the red cell membrane damage.

This paper investigated the mechanism for the rheological dysfunction of red blood cell (RBC) caused by free radicals. Normal RBCs were collected from healthy volunteers. Fenton system was added to the RBCs and allowed to react for 30 minutes in vitro. The RBC membrane molecules were damaged due to the free radicals reaction. It was found that: (1) The protein configurations changed such as the ratio decreasing in alpha-helix and increasing in both of beta-sheet and coiled-coil; (2) -P=O/-P-O chemical group ratio in phospholipids increases; (3) the molecular rotational correlation times of proteins and lipids were extremely elevated; (4) the membrane shear elastic modulus was significantly enhanced. The present results support that the chemical structure changes led by free radicals are ultimately responsible for the reduction in molecular fluidity of RBC membrane.

Elasticity↗

PubMed2000

[Effects of excessive iodine on activity of enolase in hippocampus of developing mice].

OBJECTIVE: To study the effects of excessive intake of iodine for a long term on activity of enolase in hippocampal tissues of young mice. METHODS: A hyperiodine goiter animal model was replicated with drinking water with high level of iodine. Activity of neuron specific enolase (NSE) in hippocampal tissues was determined with enzyme-linked immunosorbent assay (ELISA) for young offspring of the first and the second generations of mice with hyperiodine goiter on the 7th, 14th and 21st day of age, respectively. RESULTS: Activity of enolase in young offspring of the first and second generation of mice with hyperiodine goiter was all lower than that in controls from the day of their birth to the 30th day after birth, and that at hippocampal tissues in young mice of the second generation was significantly lower than that of the first generation on the 14th day of age. CONCLUSION: Hyperiodine can decrease activity of NSE in the brain of mice. It suggests that hyperiodine can affect NSE, and thus interfere energy supply in the brain, resulting in disturbance of neuron development and brain function.

Animals↗

PubMed2000

[Abnormal infrared effects (AIREs) of nm-Ru/GC electrode towards CO adsorption in alkaline solutions].

The adsorption of CO on electrode of nanometer thin film of Ru in 0.1 mol.L-1 NaOH solution was studied by using in-situ FTIR spectroscopy. The results revealed that the adsorbed CO in alkaline solutions is mainly in linear bonded from that yields IR absorption at around 1,960 cm-1, and a small portion of bridge bonded CO was also determined near 1,780 cm-1. The band centers of COL and COB have been red-shifted respectively about 50 and 60 cm-1 in comparison with the values measured in acid medium. The enhancement factor of IR absorption of CO on nm-Ru/GC electrode has been measured at 33 in 0.1 mol.L-1 NaOH solution, which is more than 2 times larger than the value determined in a 0.1 MH2SO4 solution.

English Abstract↗

PubMed2000

[In situ time-resolved FTIR studies of HCOOH oxidation on Pt(100)/Sb electrodes].

The electrocatalytic oxidation of formic acid on Pt(100)/Sb electrodes of different coverage of Sb was investigated by using electrochemical techniques and in situ time-resolve FTIRS. The results demonstrated that the dissociative adsorption of formic acid was inhibited by the presence of Sbad on Pt(100) surface, as a consequence HCOOH can be oxidized directly into CO2 via reactive intermediates. The rate of oxidation of formic acid varied with the coverage of Sbad. It was revealed that at a Sbad coverage of 0.24 the Pt(100)/Sb electrode exhibited the highest electrocatalytic activity for HCOOH oxidation.

English Abstract↗

PubMed2000

[In-situ FTIR spectroscopic studies of electro oxidation of ethanol in alkaline media at a nm-Pt/GC electrode].

The electro-oxidation of ethanol on a nm-Pt/GC electrode in alkaline solutions was investigated by using cyclic Voltammetry and in-situ FTIR spectroscopy. The results demonstrated that the main product of ethanol oxidation was CH3COO-, only small quantity of CH3CHO was determined simultaneously. In contrast with the dual path reaction mechanism for the oxidation of ethanol in acid media, the oxidation of ethanol in alkaline media was revealed via the intermediate process of dissociative adsorption.

English Abstract↗

PubMed2000

[The analysis of linseed oil by FTIR and FT-Raman].

Linseed oil is an important natural sanitarian oil. To qualitative analyses the linseed oil, FTIR and FT-Raman were used to identify the contents of it. It is indicated that each component has characteristic frequency, and can be discriminated from others by IR and Raman spectroscopy. This is useful for the further on-line quantitative analysis and quality control of linseed oil.

Fourier Analysis↗

PubMed2000

[Study on thermal unfolding process of trichosanthin by FTIR spectroscopy].

Fourier-transform infared spectroscopy, combined with resolution-enhancement techniques including second-derivative spectroscopy, Fourier self-deconvolution and curvefitting technique, was used to investigate the thermally induced unfolding process of anti-HIV-I toxin protein trichosanthin. During heating from 25 degrees C to 85 degrees C, the peak of Amide I shifted to 1618 cm-1 while the secondary structural contents change with the temperature. Upon cooling the protein from 85 degrees C to 25 degrees C, the contour of the Amide I do not change. All these show that the thermal unfolding of trichosanthin is an irreversible intermolecular aggregation process between 25 degrees C and 85 degrees C. The changes of secondary structures with temperature suggest the presence of folding intermediates.

Hot Temperature↗

PubMed2000

[Quantitative analysis of rutin and vitamin C by NIR FTIR].

In this paper, near-infrared diffuse reflectance spectroscopy(NIRDRS) method was used as a quantitative tool to measure the solid mixture of rutin and vitamin C by collecting NIR spectra in the range 7,000-3,900 cm-1. The quantitative mathematics model was established with partial least squares(PLS) method. The correlation coefficient was 99.75%, the standard error of Rutin was 0.363%, and the standard error of Vitamin C was 1.078%. The methods are rapid, exact and nondestructive to samples. The components of the samples can be individually analyzed with high accuracy and precision, so NIRDRS can be a useful method of quality control of pharmaceuticals in the future.

Ascorbic Acid↗

PubMed2000

[Study on unfolding process of neo-trichosanthin in the presence of GdnHCl].

Fluorescence spectroscopy and circular dichroism are effective instruments to determine the chemical unfolding process of protein solution. In this paper, both of them were selected to investigate the unfolding processes of neo-trichosanthin in the presence of GdnHCl. One GdnHCl is added, both spectra of fluorescence and circular dichroism changed remarkedly. The denaturation curve of CD ellipticity meets that of fluorescence intensive excitation at 295 nm very well. The result shows that, in the presence of GdnHCl, the unfolding of neo-trichosantin matches the two-state process well. The model is different from the model of trichosanthin that others reported previously. The mechanism will be further probed later.

Circular Dichroism↗

PubMed2000

[In situ FTIR spectrocopic studies of CO and CN- adsorbed on electrode of nanometer thin film of palladium in alkaline solutions].

The adsorption and coadsorption of CO and CN- on electrode of nanometer thin film of palladium (nm-Pd/GC) was studied by using in situ FTIR spectroscopy. The results demonstrated that the nm-Pd/GC electrode exhibited abnormal infrared effects (AIREs) in alkaline solutions as in acid solutions. The characters of AIREs, i.e., the inversion of the direction of IR band, the augmentation of FWHM and the significant enhancement of IR absorption by adsorbed species were observed in all cases of adsorption and coadsorption of CO and CN-. It has been illustrated that strong interaction is existed between adsorbed CO and CN- on nm-Pd/GC surface. The study has contributed towards understanding the surface processes of chemisorption as well as to reveal the origin of nanometer size-effects of thin film materials.

English Abstract↗

PubMed2000

[In situ FTIRS studies of CO2 reduction on thin film alloy electrodes].

The nanometer thin film alloy electrode (Sb-Pb-Pt/GC) was prepared by electrochemical methods. Excellent catalytic effect was observed on these film alloy material in the electro-reduction of carbon dioxide (CO2). The reduction can take place at potentials as high as -0.4 V. The oxidation of reduced products of CO2 on Sb-Pb-Pt/GC yielded current peaks at arrowed -0.08, 0.2 and 0.3 V, while the oxidation of reduction products on a nm-Pt/GC electrode gave rise a current peak near 0.4 V. The in situ FTIR spectroscopic studies confirmed at a molecule level that the products of CO2 reduction on Sb-Pb-Pt/GC are mainly organic acid and alcoholic compounds, while on a nm-Pt/GC electrode the production of CO2 is mainly CO species.

Alloys↗

PubMed2000

[In situ FTIR spectrocopic investigations of 1,3-butanediol oxidation on Sb and S modified Pt electrodes].

In the present paper, we studied the surface structure effect of Pt electrode modified with antimony and sulfur adatoms towards 1,3-Butanediol oxidation. The results demonstrated that the modification of Sb and S both inhibited the dissociative adsorption of 1,3-Butanediol into CO, which is the main source of self-poisoning in electrocatalysis of small organic molecules. At lower potentials, the principal oxidation pathway of 1,3-Butanediol on Pt/Sbad electrode is towards the production of C=O. However, at higher potentials, the products of CO2 increased. The presence of S(ad) inhibited the oxidation of 1,3-BD at low potentials(< 0.8 V), and yield mainly acid species as products at higher potentials(> 0.8 V).

Antimony↗

PubMed2000

[In situ FTIR studies of CO adsorption on palladium loading zeolite electrode].

Adsorption of CO on palladium loading zeolite electrode supported on Pt or GC substrate was studied by in situ MSFTIR spectroscopy. The results demonstrated that the geometry of faujasite supercages favors the formation of bridge-bonded CO species. The enhanced IR adsorption of CO adsorbed on Pd clusters located in the supercages of zeolite has been observed for the first time, which is a new phenomenon and differs from the abnormal infrared effects discovered by our group and the surface enhanced infrared absorption phenomenon reported in the literature.

English Abstract↗