Biomedical subjects

Mi Yan

Publications and source records attributed to Mi Yan.

14 recordsLinked to original sources

PubMed2006

"Sleepiness" is serious in adolescence: two surveys of 3235 Canadian students.

BACKGROUND: Evidence is growing that sleep problems in adolescents are significant impediments to learning and negatively affect behaviour, attainment of social competence and quality of life. The objectives of the study were to determine the level of sleepiness among students in high school, to identify factors to explain it, and to determine the association between sleepiness and performance in both academic and extracurricular activities METHODS: A cross-sectional survey of 2201 high school students in the Hamilton Wentworth District School Board and the Near North District School Board in Ontario was conducted in 1998/9. A similar survey was done three years later involving 1034 students in the Grand Erie District School Board in the same Province. The Epworth Sleepiness Scale (ESS) was used to measure sleepiness and we also assessed the reliability of this tool for this population. Descriptive analysis of the cohort and information on various measures of performance and demographic data were included. Regression analysis, using the generalised estimating equation (GEE), was utilized to investigate factors associated with risk of sleepiness (ESS>10). RESULTS: Seventy per cent of the students had less than 8.5 hours weeknight sleep. Bedtime habits such as a consistent bedtime routine, staying up late or drinking caffeinated beverages before bed were statistically significantly associated with ESS, as were weeknight sleep quantity and gender. As ESS increased there was an increase in the proportion of students who felt their grades had dropped because of sleepiness, were late for school, were often extremely sleepy at school, and were involved in fewer extracurricular activities. These performance measures were statistically significantly associated with ESS. Twenty-three percent of the students felt their grades had dropped because of sleepiness. Most students (58-68%) reported that they were "really sleepy" between 8 and 10 A.M. CONCLUSION: Sleep deprivation and excessive daytime sleepiness were common in two samples of Ontario high school students and were associated with a decrease in academic achievement and extracurricular activity. There is a need to increase awareness of this problem in the education and health communities and to translate knowledge already available to strategies to address it.

Adolescent↗

PubMed2006

[Expression and role of endostatin in the retina of oxygen-induced retinopathy mouse model].

OBJECTIVE: To investigate the effect of endostatin on the pathogenesis and development of retinal neovascula animal model of oxygen-induced retinopathy. METHODS: The animal model of oxygen-induced retinopathy was made by subjecting postnatal mice to hyperoxic conditions (5 days) followed by normoxic conditions. Retinal angiogram was taken by using high molecular weight fluorescein-dextran. The degree of hyperoxia-induced neovascularization in serial paraffin cross-sections was quantified by counting the number of vascular cell nuclei on vitreal side of the internal limiting membrane. The expression of ES and VEGF in the oxygen-induced retina was observed by immunohistochemistry. RESULTS: We successfully constructed the oxygen-induced retinopathy mouse model. FITC-dextran retinal angiography indicated that hyperoxia could produce constriction of retinal vasculature and vaso-obliteration or irreversible closure of many capillary channels and eventually result in non-perfused area in the post-area of retina surrounding the optic disk. Relatively, hypoxia could lead to dilation and torsion of retinal vessels. There were averagely 22 neovascular nuclei per cross-section of eyes in the hyperoxia group and less than 3 nuclei per cross-section of eyes in the control group (P < 0.05). The expressions of ES and VEGF in the retina under hyperoxia were stronger than those under normoxia, expecially the expression of VEGF. CONCLUSION: Taking measures to up-regulate the expression of endogenetic endostatin may have the potential for effective treatment of retinal ischemic neovascularization.

Animals↗

PubMed2006

[Enzyme activities in Paeonia ostii rhizosphere and non-rhizosphere soil of Tongling copper mining].

The study on the calatase, polyphenol-oxidase, invertase, urease and phosphatase activities in Paeonia ostii rhizosphere and non-rhizosphere soil of Tongling copper mining showed that all test enzyme activities were higher in rhizosphere than in non-rhizosphere soil. Soil calatase, urease and phosphatase were sensitive to heavy metals pollution, and their activities could be used as the indicators of heavy metals' joint pollution. The effects of rhizosphere environment on the soil enzyme activities were in the sequence of phosphatase > urease > calatase > invertase > polyphenol-oxidase, and the affecting rate was 131.562%, 92.492%, 87.557%, 59.673% and 34.076%, respectively. The test enzyme activities were negatively correlated with soil heavy metals pollution, and the correlation coefficients were all higher than -0.898, suggesting the inhibitory effects of heavy metals' joint pollution on soil enzyme activities. P. ostii could effectively improve soil environment, and thus, enhance the activities of soil enzymes.

Catalase↗

PubMed2006

[Coercion and damage of Cu pollution on Artemisia lavandulaefolia growth].

By the method of solution culture, this paper studied the coercion and damage of Cu pollution on the growth of Artemisia lavandulaefolia. The Cu concentration was set as 2.5, 5, 10, 20 and 40 mg x L(-1), experimental duration was 14 days, and the growth and physiological indices of plants were tested. The results showed that the growth of A. lavandulaefolia was stimulated at low Cu concentration (2.5 mg x L(-1)), while inhibited at higher Cu concentrations (5 to approximately 40 mg x L(-1)). There was a significant negative correlation between each growth index and Cu concentration, and pigments contents had the similar trend. The sensibility of various photosynthetic pigments to Cu was in the order of chlorophyll a > chlorophyll a + b > chlorophyll b > carotenoid. Cell membrane permeability, O2 generation rate, and MDA content decreased slightly at 2.5 mg Cu x L(- 1) and then increased with increasing Cu concentration. The activities of POD, SOD and CAT increased first but decreased then with the increasing Cu concentration, and the endurance index of root showed the same trend, being > 0.5 at the Cu concentration less than 20 mg x L(-1) while decreased to 0.36 at 40 mg Cu x L(-1).

Artemisia↗

PubMed2006

[Study on crossed and uncrossed disparity evoked potential of dynamic random dot stereogram].

OBJECTIVE: To analyze the disparity evoked potentials (DEP) of fine disparities, coarse disparities, crossed disparities and uncrossed disparities and provide parameters of impersonal examining stereopsis. METHODS: A software package for generating dynamic random dot stereogram (DRDS) was developed as a visual stimulus to elicit DEP in 30 normal subjects. The DEP of every subject was recorded in different crossed and uncrossed disparity stimuli (4', 8', 15', 23', 30', 45', 53', 60', 72', 87', 102', 124', 150' of arc). RESULTS: (1) the constant negative-positive complex wave was observed in different disparity stimuli. (2) The N wave's latency of -45' was the longest, the N wave's latency of -150' was the shortest among crossed disparities. The N wave's latency of 4', 23' was the longest, the N wave's latency of 124' was the shortest among uncrossed disparities. (3) The amplitude peak of P wave occurred at -23', -60', -150' among crossed disparities. The amplitude peak of P wave occurred at 15', 45', 72' among uncrossed disparities. (4) All characteristic crossed disparities were smaller than the uncrossed disparities. The change orderliness of small crossed disparities was different from that of small uncrossed disparities. CONCLUSIONS: The N wave's latency and the P wave's amplitude can be used as parameters to impersonally examine stereopsis. These results suggest that stereopsis can be divided into fine crossed stereopsis, fine uncrossed stereopsis, coarse crossed stereopsis, and coarse uncrossed stereopsis.

Adolescent↗

PubMed2005

Downregulation of vascular endothelial growth factor and integrinbeta3 by endostatin in a mouse model of retinal neovascularization.

Retinal neovascularization is among the leading causes of vision impairment throughout the world. Intraocular expression of vascular endothelial growth factor (VEGF), an angiogenic protein, and integrins, a group of cell adhesion molecules, is closely correlated with neovascularization in such neovascular diseases. The purpose of this study is to determine the effect of endostatin, a potent anti-angiogenic factor, on gene expression of vascular endothelial growth factor (VEGF) and integrinbeta3 in a mouse model of oxygen-induced retinopathy. C57BL/6 mice were given intravitreous injections of 1.0 microg endostatin at P12. At P17, retinal VEGF and integrinbeta3 mRNA levels were measured by real-time quantitative PCR in the hyperoxia mice and in the endostatin-treated mice. Analysis of 12 separate experiments revealed a 3.5-fold decrease in VEGF levels between hyperoxia mice and endostatin-treated mice (p<0.01) and a 2.5-fold decrease in integrinbeta3 levels between hyperoxia mice and endostatin-treated mice (p<0.01). These data suggest that intraocular expression of VEGF and integrinbeta3 mRNA is down-regulated by endostatin, which may provide a new therapeutic approach for ocular neovascularization.

Angiogenesis Inhibitors↗

PubMed2005

Preparation of high-permeability NiCuZn ferrite.

Appropriate addition of CuO/V2O5 and the reduction of the granularity of the raw materials particle decrease the sintering temperature of NiZn ferrite from 1200 degrees C to 930 degrees C. Furthermore, the magnetic properties of the NiZn ferrite prepared at low temperature of 930 degrees C is superior to that of the NiZn ferrite prepared by sintering at high temperature of 1200 degrees C because the microstructure of the NiZn ferrite sintered at 930 degrees C is more uniform and compact than that of the NiZn ferrite sintered at 1200 degrees C. The high permeability of 1700 and relative loss coefficient tandelta/mu(i) of 9.0x10(-6) at 100 kHz was achieved in the (Ni0.17Zn0.63Cu0.20)Fe1.915O4 ferrite.

Copper↗

PubMed2005

[The effect of blue light on mitochondrial membrane potential and cytochrome C of cultured human retinal pigment epithelium cells].

OBJECTIVE: To answer the question whether mitochondrial permeability transition (MPT) participates in blue light-induced damage to human retinal pigment epithelium (RPE) cells, this study was directed at assessing the effect of blue light on mitochondrial membrane potential (delta psi(m)) and cytochrome C (Cyt C) of cultured human RPE cells. METHODS: Human RPE cells were exposed to blue light (wave length 470-490 nm); delta psi(m) was measured by rhodamine 123 staining and subsequent flow cytometry. Three groups were investigated: Group A (exposure to different intensity of blue light); group B (exposure to identical intensity for different duration); group C (exposure to identical intensity and duration, different prolongation of post-exposure culture). Cyt C activity was assayed by ELISA. Caspase-3 was detected by colorimetric assay. In these aspects, two groups were investigated: Group I [(2000+/-500) 1x for 6 h]; Group II [(2000+/-500) 1x for 12 h]. RESULTS: When human RPE cells were exposed to blue light, the more pronounced decrease of delta psi(m) was consistent with the increase of light intensity in group A. Pronounced decrease of delta psi(m) was seen at 6 h and 12 h of exposure duration in group B. At 6 h prolongation of post-exposure culture in group C, the decrease of delta psi(m) was observed, lasting 48 h. The concentration of Cyt C was detected; no significant changes were found at 6 h and 12 h prolongation of post-exposure culture, but a significant increase was found at 24 h and 36 h post-exposure in the two groups. The increase was more significant in Group II than in Group I at 24 h post-exposure. The activity change of caspase-3 was not found in the two groups. CONCLUSION: Blue light exposure over threshold can induce damage to human RPE cells, probably by triggering the mitochondrial permeability transition, which results in the decrease of delta psi(m) and the release of cytochrome C.

Caspase 3↗

PubMed2005

[Heavy metals pollution of Paeonia ostii land at copper-tailings reservoir of Tongling city: a preliminary study].

The study on the soil and Paeonia ostii Cu, Cd, Pb and Zn at the copper-tailings reservoir of Tongling City, Anhui Province showed that the forms and contents of test heavy metals were differed in Paeonia ostii-planted and control soils. The Cu and Cd contents in control soil were 4.36-14.43 and 3.67-3.86 times of the 2nd national standard for soil environmental quality, respectively, and the composite pollution index of the heavy metals in Paeonia ostii-planted soil was up to 5.607. The heavy metals content in Paeonia ostii leaf and root-stem was in order of Cu>Zn>Pb>Cd, and that in Paeonia ostii stem and root- peel was Zn>Cu>Pb>Cd. The comparison of the heavy metals contents in Paeonia ostii with the criterion about herbal medicine showed that the Cu content in Paeonia ostii was 1.43-2.53 times of the criterion, and the Cd content was 1.17-3.17 times of the criterion.

Cadmium↗

PubMed2004

Perspectives on the metallic interconnects for solid oxide fuel cells.

The various stages and progress in the development of interconnect materials for solid oxide fuel cells (SOFCs) over the last two decades are reviewed. The criteria for the application of materials as interconnects are highlighted. In-terconnects based on lanthanum chromite ceramics demonstrate many inherent drawbacks and therefore are only useful for SOFCs operating around 1000 degrees C. The advance in the research of anode-supported flat SOFCs facilitates the replacement of ceramic interconnects with metallic ones due to their significantly lowered working temperature. Besides, interconnects made of metals or alloys offer many advantages as compared to their ceramic counterpart. The oxidation response and thermal expansion behaviors of various prospective metallic interconnects are examined and evaluated. The minimization of contact resistance to achieve desired and reliable stack performance during their projected lifetime still remains a highly challenging issue with metallic interconnects. Inexpensive coating materials and techniques may play a key role in pro-moting the commercialization of SOFC stack whose interconnects are constructed of some current commercially available alloys. Alternatively, development of new metallic materials that are capable of forming stable oxide scales with sluggish growth rate and sufficient electrical conductivity is called for.

Electric Power Supplies↗

PubMed2003

[Stereopsis of the patients after cataract extraction and intraocular lens implantation].

OBJECTIVE: To understand the stereopsis of the patients after cataract extractation and intraocular lens implantation and the related factors. METHODS: In this study were examined the stereopsis of 30 patients who had undergone cataract extraction and intraocular lens implantation and whose post-operative vision acuity measurements were 0.5 or higher. RESULTS: These patients' steroacuity, anisometropia, aniseikonia and scotoma were: 407.67" +/- 390.19", 1.53D +/- 1.96D, 3.93% +/- 3.51%, 3.17" +/- 1.98" respectively. There was no significant correlation between steroacuity anisometropia and aniseikonia. There was siganificant positive correlation between steroacuity and scotoma. CONCLUSIONS: Intraocular lens implantation may ameliorate anisometropia and aniseikonia of the patients after cataract extraction and reduce the damage to stereopsis.

Adult↗

PubMed2003

[The response of bFGF, FGFR1, Bcl-2 and caspase-3 to visible light in cultured human retinal pigment epithelium cells].

OBJECTIVE: To assess the expression of bFGF, FGFR1, Bcl-2 and caspase-3 in human RPE cells exposed to visible light in vitro. METHODS: Cultured human RPE cells were exposed to visible light [(2,000 +/- 500) Lux] for 12 hours. Immunocytochemical staining, enzyme-linked assays and RT-PCR were used to determine the expression of bFGF and its receptor FGFR1, Bcl-2 as well as the activity of caspase-3. RESULTS: (1) Bcl-2 was detected in normal cultured human RPE cells. No significant change was found at 6 or 12 hours after light exposure (P > 0.05). But 24 hours after exposure, a significantly decreasing of Bcl-2 expression was observed (P < 0.01). The changes in expression of Bcl-2 mRNA paralleled to the changes in its protein, except that differences could be detected earlier viz. 12 hours after exposure. (2) The upregulation of bFGF and FGFR1 mRNA expression occurred with longer period of light exposure (P < 0.05). (3) The upregulation of caspase-3 activity was detected 6 hours after light exposure, and was more significant over 6 hours and 12 hours (P < 0.05). No significant difference was found between 12 hours and 24 hours exposure (P > 0.05). CONCLUSIONS: Visible light exposure over threshold causes upregulation of endogenous bFGF and FGFR1, downregulation of Bcl-2 and activation of caspase-3 in human RPE cells.

Apoptosis↗

PubMed2002

[An epidemiological study on senile cataract in urban and rural areas of Chengdu].

OBJECTIVE: To find out the status and distribution characteristics of senile cataract, which is one of the common disease affecting the quality of life of the elderly people. METHODS: One thousand and sixteen people aged 60 or more in the urban and rural areas of Chengdu were included by cluster random sampling and investigated by questionnaire method and medical examination. RESULTS: It was found that the prevalence of senile cataract was 52.3% in urban area and 51.3% in rural area. The prevalence was higher in women than in men, and it increased with age. The prevalence of senile cataract by past diagnosis was lower than that by present medical examination; this difference was found obvious in the rural area. CONCLUSION: The prevention and treatment of senile cataract should be strengthened.

Aged↗

PubMedDate not supplied

A method for predicting critical load evaluating adhesion of coatings in scratch testing.

In this paper based on the experiment principle of evaluating adhesion property by scratch testing, the peeling mechanism of thin films is discussed by applying contact theory and surface physics theory. A mathematical model predicting the critical load is proposed for calculating critical load as determined by scratch testing. The factors for correctly evaluating adhesion of coatings according to the experimental data are discussed.

Ceramics↗