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Biomedical subjects

Yan Wang

Publications and source records attributed to Yan Wang.

At least 433 records · Page 24Linked to original sources
PubMed2004

[Established prolonged selenium deficiency of the SD rat animal model breed third generation in series].

OBJECTIVE: To establish selenium deficiency of the breed third generation SD rats animal model in series. METHODS: A Se-deficient diet mainly based on Se-deficient yeast. Groups of six female and six male SD rats original generation (F0) were fed on one of the five diets: (1) selenium- and iodine-adequate control group (Se+I+ group. Selenium: 0.1-0.3 microg/g, iodine > or = 0.2 microg/g), (2) selenium-deficient iodine-adequate group 1 (Se-I+ group. Selenium: 0.02 microg/g, iodine > or = 0.2 microg/g), (3) selenium-deficient iodine-adequate group 2 (Se-I+ group2. Selenium: 0.005 microg/g, iodine > or = 0.2 microg/g), (4) selenium-adequate iodine-deficient group (Se+I- group. Selenium: 0.1-0.3 microg/g, iodine: 0.04 microg/g), (5) selenium- and iodine-deficient group (Se-I- group. Selenium: 0.01 microg/g, iodine: 0.04 microg/g). Selenium-deficient iodine-adequate group2 had been deled since generation 1 (F1). Serum Se and thyroid hormone concentrations, whole blood glutathione peroxidase (GSH-Px) activities, the weight, childbearing and livability were examined. RESULTS: There were durative lower Se concentrations in serum and lower GSH-Px activities in blood, and the weight, childbearing and livability reduced in Se- group and Se-I- group from F0 to F3. CONCLUSION: We have established prolonged selenium deficiency of the SD rat animal model breed third generation in series successfully.

Animals↗
PubMed2004

[Investigation on the detection of pesticide residue in vegetable based on infrared spectroscopy].

In this paper, the mid-infrared Attenuated Total Reflection (ATR) spectra of two slathered pesticides dichlorvos and trichlorfon in vegetable juice solution have been investigated. It can be concluded that within characteristic absorption region of the two pesticides in the mid-infrared range, the pigments inside the vegetable have no effect on the pesticide' s absorbance; pesticides in standard solution and vegetable juice solution share almost the same absorbance characteristics. These results indicate that: the authors can use the model built by the absorbance data of pesticides in water solution to simulate their absorbance in vegetable solution, then based upon infrared spectroscopy, the direct detection of pesticide residue on the vegetable can be achieved; it also provides a possible way of rapid detection on vegetable in the future.

Carbon Dioxide↗
PubMed2004

[Measurement of borneol based on near infrared spectroscopy].

Infrared spectroscopy can provide integrated information of samples, and is easy to be applied to on-line control. So quality control specification of Chinese drugs can be improved by utilizing this method for the production of Chinese drugs. This method can accelerate the modernization process of Chinese drugs. Borneol is an effective constituent in lots of active Chinese drugs. The spectral characteristics of borneol in near infrared region were investigated in this paper. The characteristic absorption peaks of bomeol were found by measuring its spectra in near infrared band. There are five absorption peaks of borneol close to 4828, 5003, 5736, 7044 and 8387 cm(-1), respectively. Establishing a partial least square (PLS) model can get optimal results in model building experiment. The predictive results show that the linear relationship between twenty-five samples' predicted values and real values is good with regard to the content of borneol. In calibration model, the root mean square error of prediction (RMSEP) of the content of borneol is 0.28 mg x mL(-1) and the number of the principal components is equal to two. The experimental results show that infrared spectroscopy can be used as a means in the field of quality control of Chinese drugs and the measurement of effective constituents of Chinese drugs.

Calibration↗
PubMed2004

[The relationship between hypertension and cerebral hemodynamic scores of vascular function accumulative].

OBJECTIVE: To probe into the relationship between hypertension and hemodynamic score of cerebral vascular accumulative function by though studying the history of hypertension and level of blood pressure. METHODS: The database of blood pressure and cerebral vascular hemodynamic indexes (CVHI) were from baseline data and measurement in a cohort. 18,512 participants who met the included criteria were enlisted in the study. The function scores were estimated using uniform methods according to CVHI. Participants were grouped by age, years of having hypertension and level of blood pressure. Differences of the function score between different groups were compared. RESULTS: The function score in hypertension group was significantly lower than that of normal tension group, which decreased by 13.3 points. Within 5 years of hypertension history, the function score decreased as course of hypertension prolonged. The same trend was found between the score and level of both systolic and diastolic blood pressure. When systolic blood pressure elevated to 140 mmHg or diastolic blood pressure elevated to 95 mmHg, the function score was below 75 points. CONCLUSION: There were significant relationship between decrease of the function scores and medical history, course of hypertension as well as level of blood pressure.

Adult↗
PubMed2004

Thiocyanate elution measurement of relative affinity of phage antibodies.

Human antibodies generated by phage antibody technology have been widely used in the immunotherapy of various diseases. Among the characteristics of these therapeutic antibodies, affinity is one of the most important determinants of their biological efficacy. The binding of an antibody and its corresponding antigen could be disrupted by thiocyanate solution of different concentrations, depend upon the affinity of the antibody. This mechanism has been adopted to determine the relative affinity of monoclonal or polyclonal antibodies in routine immunological practice. Correlation between the elution method and other techniques that measure the affinity such as equilibrium dialysis and biospecific interaction analysis (BIA) has been established. Here we describe the applications of the thiocyanate elution method in the determination of the relative affinity index (RAI) of phage antibodies (Phabs). Five clone antibodies, including 3 clones of anti-keratin antibodies (AK1, AK2 and AK3) and 2 clones of anti-HBsAg antibodies (HB1 and HB2) were selected to express Phabs and Fabs, and the RAI were determined by ELISA after thiocyanate elution. A HRP-conjugated anti-M13 was used as secondary antibody for Phabs and HRP-goat-anti-human Fab was used for Fabs. The affinity ranks of the Phabs were compared with that of the Fab fragments. The results showed that all the Phabs tested were tolerant to thiocyanate treatment. The relative affinity rank of 5 Phabs coincided well with that of their corresponding Fabs. We conclude that the thiocyanate elution can be used as an easy and rapid method to measure and compare the relative affinity of Phabs.

Antibodies↗
PubMed2003

Semi-quantitative expression analysis of ephrin mRNAs in the deafferented hippocampus.

To search for gene expression changes probably responsible for deafferentation-induced reorganization in the brain, we have analyzed the expression of mRNAs for ephrin-A1, -A2, -A3, -A5 and -B1 in the rat hippocampus following transection of the entorhinal afferents by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). We found that their expression in the deafferented hippocampus increased significantly by 7 days, reached the maximum at 14 days and almost recovered to control levels by 60 days post-lesion. It is notable that the up-regulation of ephrin mRNAs occurs during the reorganization in the deafferented hippocampus, suggesting that ephrins may be involved in the plasticity events of the adult brain after lesion.

Analysis of Variance↗
PubMed2003

The Arabidopsis homeobox gene, ATHB16, regulates leaf development and the sensitivity to photoperiod in Arabidopsis.

This report describes the characterisation of ATHB16, a novel Arabidopsis thaliana homeobox gene, which encodes a homeodomain-leucine zipper class I (HDZip I) protein. We demonstrate that ATHB16 functions as a growth regulator, potentially as a component in the light-sensing mechanism of the plant. Endogenous ATHB16 mRNA was detected in all organs of Arabidopsis, at highest abundance in rosette leaves. Reduced levels of ATHB16 expression in transgenic Arabidopsis plants caused an increase in leaf cell expansion and consequently an increased size of the leaves, whereas leaf shape was unaffected. Transgenic plants with increased ATHB16 mRNA levels developed leaves that were smaller than wild-type leaves. Therefore, we suggest ATHB16 to act as a negative regulator of leaf cell expansion. Furthermore, the flowering time response to photoperiod was increased in plants with reduced ATHB16 levels but reduced in plants with elevated ATHB16 levels, indicating that ATHB16 has an additional role as a suppressor of the flowering time sensitivity to photoperiod in wild-type Arabidopsis. As deduced from the response of transgenic plants with altered levels of ATHB16 expression in hypocotyl elongation assays, the gene may act to regulate plant development as a mediator of a blue light response.

Amino Acid Sequence↗
PubMed2003

Phosphoinositide 3-kinase-mediated activation of cofilin phosphatase Slingshot and its role for insulin-induced membrane protrusion.

Cofilin plays an essential role in actin filament dynamics and membrane protrusion in motile cells. Cofilin is inactivated by phosphorylation at Ser-3 by LIM kinase and reactivated by dephosphorylation by cofilin-phosphatase Slingshot (SSH). Although cofilin is dephosphorylated in response to various extracellular stimuli, signaling pathways regulating SSH activation and cofilin dephosphorylation have remained to be elucidated. Here we show that insulin stimulates the phosphatase activity of Slingshot-1L (SSH1L) and cofilin dephosphorylation in cultured cells, in a manner dependent on phosphoinositide 3-kinase (PI3K) activity. Consistent with this, the level of Ser-3-phosphorylated cofilin is increased in PTEN (phosphatase and tensin homolog deleted in chromosome 10)-overexpressing cells and decreased in PTEN-deficient cells. Insulin induced the accumulation of SSH1L and active Akt (a downstream effector of PI3K), together with a PI3K product phosphatidylinositol 3,4,5-trisphosphate, onto membrane protrusions. Cofilin, but not Ser-3-phosphorylated cofilin, accumulated in membrane protrusions in insulin-stimulated cells, indicating that cofilin is dephosphorylated in these areas. Finally, suppression of SSH1L expression by RNA interference abolished insulin-induced cofilin dephosphorylation and the membrane protrusion. These findings suggest that SSH1L is activated downstream of PI3K and plays a critical role in insulin-induced membrane protrusion by dephosphorylating and activating cofilin.

Actin Depolymerizing Factors↗
PubMed2003

Simple and rapid catalytic spectrophotometric determination of superoxide anion radical and superoxide dismutase activity in natural medical vegetables using phenol as the substrate for horseradish peroxidase.

The coupling reaction of 4-aminoantipyrine (4-AAP) with phenol using the superoxide anion radical (O2-*) as oxidizing agent under the catalysis of horseradish peroxidase (HRP) was studied. Based on the reaction, O2-* produced by irradiating vitamin B2 (VB2) was spectrophotometrically determined at 510 nm. Under the optimum experimental conditions, the relationship between A510 and O2-* concentration was linear in the range 9.14x10(-6)-1.2x10(-4) mol L(-1). The detection limit was determined to be 1.37x10(-6) mol L(-1). A possible reaction mechanism was discussed. The effect of interferences and surfactants on the determination of O2-* was also investigated. The proposed method was applied to determine superoxide dismutase activity in garlic, scallion, and onion with satisfactory results.

Catalysis↗
PubMed2003

Progress in the development of a recombinant vaccine for human hookworm disease: the Human Hookworm Vaccine Initiative.

Hookworm infection is one of the most important parasitic infections of humans, possibly outranked only by malaria as a cause of misery and suffering. An estimated 1.2 billion people are infected with hookworm in areas of rural poverty in the tropics and subtropics. Epidemiological data collected in China, Southeast Asia and Brazil indicate that, unlike other soil-transmitted helminth infections, the highest hookworm burdens typically occur in adult populations, including the elderly. Emerging data on the host cellular immune responses of chronically infected populations suggest that hookworms induce a state of host anergy and immune hyporesponsiveness. These features account for the high rates of hookworm reinfection following treatment with anthelminthic drugs and therefore, the failure of anthelminthics to control hookworm. Despite the inability of the human host to develop naturally acquired immune responses to hookworm, there is evidence for the feasibility of developing a vaccine based on the successes of immunising laboratory animals with either attenuated larval vaccines or antigens extracted from the alimentary canal of adult blood-feeding stages. The major antigens associated with each of these larval and adult hookworm vaccines have been cloned and expressed in prokaryotic and eukaryotic systems. However, only eukaryotic expression systems (e.g., yeast, baculovirus, and insect cells) produce recombinant proteins that immunologically resemble the corresponding native antigens. A challenge for vaccinologists is to formulate selected eukaryotic antigens with appropriate adjuvants in order to elicit high antibody titres. In some cases, antigen-specific IgE responses are required to mediate protection. Another challenge will be to produce anti-hookworm vaccine antigens at high yield low cost suitable for immunising large impoverished populations living in the developing nations of the tropics.

Adolescent↗
PubMed2003

Tris[diphenyl(2-pyridyl)phosphine]-micro(3)-iodo-tri-micro(3)-sulfido-sulfidotrisilvertungsten dichloromethane hemisolvate.

The title compound, [Ag(3)WIS(4)(C(17)H(14)NP)(3)].0.5CH(2)Cl(2), is a cubane-type heterometallic cluster containing diphenyl(2-pyridyl)phosphine (Ph(2)PPy). The pyridyl group of Ph(2)PPy remains uncoordinated, so the Ph(2)PPy ligand is monodentate and coordinates to one Ag atom. The W atom and three Ag atoms form a distorted tetrahedral geometry, capped by one I atom and three S atoms.

Journal Article↗
PubMed2003

Up-regulation of endothelial nitric-oxide synthase by endothelium-derived hyperpolarizing factor involves mitogen-activated protein kinase and protein kinase C signaling pathways.

Cytochrome P450 (P450)-dependent metabolites of arachidonic acid, the epoxyeicosatrienoic acids (EETs), are proposed to be endothelium-derived hyperpolarizing factors (EDHF) that affect vascular tone; however, the effects of EDHF on endothelial-derived nitric oxide biosynthesis remain unknown. We examined the regulation of endothelial nitric-oxide synthase (eNOS) by EDHF and investigated the relevant signaling pathways involved. The P450 epoxygenases CYP102 F87V mutant, CYP2C11-CYPOR, and CYP2J2 were transfected into cultured bovine aortic endothelial cells, and the effects of endogenously formed or exogenously applied EETs on eNOS expression and activity were assessed. Transfection with the P450 epoxygenases led to increased eNOS protein expression, an effect that was attenuated by cotreatment with the P450 inhibitor 17-ODYA. Northern analysis demonstrated that P450 transfection led to increased eNOS mRNA levels consistent with an effect at the pretranslational level. P450 epoxygenase transfection resulted in increased eNOS activity as measured by the conversion of L-arginine to L-citrulline. Addition of synthetic EETs (50-200 nM) to the culture media also increased eNOS expression and activity. Treatment with mitogen-activated protein kinase (MAPK), MAPK kinase, and protein kinase C inhibitors apigenin, 2'-amino-3'-methoxyflavone (PD98059), and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), respectively, significantly inhibited the effects of P450 transfection on eNOS expression. Overexpression of P450 epoxygenases or addition of synthetic EETs increased Thr495 phosphorylation of eNOS, an effect that was inhibited by both apigenin and PD98059. Overexpression of P450 epoxygenases in rats resulted in increased aortic eNOS expression, providing direct evidence that EDHF can influence vascular eNOS levels in vivo. Based on this data, we conclude that EDHF up-regulates eNOS via activation of MAPK and protein kinase C signaling pathways.

Animals↗
PubMed2003

Prenatal exposure of rats to Ginkgo biloba extract (EGb 761) increases neuronal survival/growth and alters gene expression in the developing fetal hippocampus.

Hippocampal neuron survival/growth and gene expression have been examined after prenatal (in utero) exposure of rats to EGb 761, a leaf extract of Ginkgo biloba. Oral administration of EGb 761 (100 or 300 mg/kg/day) to pregnant dams for 5 days increased the number of hippocampal neurons (maintained in culture) of their fetuses, indicating a neurotrophic effect of the extract. Using large-scale oligonucleotide microarrays containing over 8000 combined rat genes and expressed sequence tag clusters, it was shown that treatment of pregnant dams with EGb 761 (25, 50 or 100 mg/kg/day for 5 days) altered the expression of 187 genes in the hippocampi of male fetuses and 160 genes in those of female fetuses. Using gene-cluster analysis, these genes were grouped into 18 distinct clusters for males and 17 distinct clusters for females. Among these clusters, 35 genes shared a common expression pattern in male and female hippocampal development. Of these genes, the changes observed in insulin growth factor II, insulin growth factor binding protein 2, testosterone repressed prostate message-2, glutathione-dependent dehydroascorbate reductase, lipoprotein lipase, guanylate cyclase and DNA binding protein Brn-2 were confirmed by real-time quantitative polymerase chain reaction. These findings, which have provided the first genetic profile of the effects of EGb 761 on the developing rat hippocampus, increase our understanding of the molecular and genetic programs that are activated by the extract. These effects of EGb 761 may underlie its neuroprotective properties.

Animals↗
PubMed2003

MX1013, a dipeptide caspase inhibitor with potent in vivo antiapoptotic activity.

1. Caspases play a critical role in apoptosis, and are considered to be key targets for the design of cytoprotective drugs. As part of our antiapoptotic drug-discovery effort, we have synthesized and characterized Z-VD-fmk, MX1013, as a potent, irreversible dipeptide caspase inhibitor. 2. MX1013 inhibits caspases 1, 3, 6, 7, 8, and 9, with IC50 values ranging from 5 to 20 nm. MX1013 is selective for caspases, and is a poor inhibitor of noncaspase proteases, such as cathepsin B, calpain I, or Factor Xa (IC50 values >10 microm). 3. In several cell culture models of apoptosis, including caspase 3 processing, PARP cleavage, and DNA fragmentation, MX1013 is more active than tetrapeptide- and tripeptide-based caspase inhibitors, and blocked apoptosis at concentrations as low as 0.5 microm. 4. MX1013 is more aqueous soluble than tripeptide-based caspase inhibitors such as Z-VAD-fmk. 5. At a dose of 1 mg kg-1 i.v., MX1013 prevented liver damage and the lethality caused by Fas death receptor activation in the anti-Fas mouse-liver apoptosis model, a widely used model of liver failure. 6. At a dose of 20 mg kg-1 (i.v. bolus) followed by i.v. infusion for 6 or 12 h, MX1013 reduced cortical damage by approximately 50% in a model of brain ischemia/reperfusion injury. 7. At a dose of 20 mg kg-1 (i.v. bolus) followed by i.v. infusion for 12 h, MX1013 reduced heart damage by approximately 50% in a model of acute myocardial infarction. 8. Based on these studies, we conclude that MX1013, a dipeptide pan-caspase inhibitor, has a good combination of in vitro and in vivo properties. It has the ability to protect cells from a variety of apoptotic insults, and is systemically active in three animal models of apoptosis, including brain ischemia.

Amino Acid Chloromethyl Ketones↗
PubMed2003

[Prevalence of low vision and blindness in defined populations in rural and urban areas in Beijing].

OBJECTIVE: To investigate the prevalence and causes of low vision and blindness in Beijing residents aged 40 and over. METHODS: 4,451 residents aged 40 and over in 3 rural communities and 5 urban communities in Beijing underwent eye examination, including examination of distant and near visual acuity (VA), best corrected distant and near VA, pinhole VA, and visual field, slit lamp biomicroscopy, and dilated ocular examination in the form of in-home survey by defined population-based sampling. The medical history was surveyed too. The data were analyzed based on the criteria of the World Health Organization. RESULTS: The general prevalence rates of low vision and blindness were 0.99% (95% CI: 0.70-1.28) and 0.39% (95% CI: 0.21-0.57) respectively. The prevalence rate of low vision in females was 1.45%, 2.23 times that of males (0.65%) (OR: 1.97, 95% CI: 1.00-3.95). The prevalence rate of low vision of rural residents was 1.76%, 2.89 times that of urban residents (0.61%) (OR: 2.93, 95% CI: 1.43-6.11). The prevalence rate of blindness in females was 0.64% and 0.37% in males. The prevalence rate of blindness of rural residents was 1.06%, 2.04 times that of the urban residents (0.52%) (OR: 3.77, 95% CI: 1.41-10.62). The 3 major causes of blindness were cataract (37.50%), glaucoma (29.20%), and high myopic macular degeneration (8.30%). The prevalence of blindness increased with age. CONCLUSION: The prevalence rates of low vision and blindness are higher in the rural areas. Cataract, glaucoma, and high myopic macular degeneration are the major causes of blindness. The prevalence of low vision and blindness are influenced by age, sex; area, health care level, educational level, and environmental factors.

Adult↗
PubMed2003

Extraction of carotenoids from feces, enabling the bioavailability of beta-carotene to be studied in Indonesian children.

Previously, we have presented a method for quantifying beta-carotene bioavailability based on analysis in serum, following administration of (13)C-labeled beta-carotene. Because stool samples can be collected noninvasively, we have now extended the method to measure the bioavailability based on measurements in feces. An extraction method was developed to enable measurement of concentrations and degree of isotopic enrichment of retinol, retinyl palmitate and carotenoids in feces. Relative bioavailability of beta-carotene from pumpkin (n = 6) was found to be 1.8 times (interval, 0.6, 5.5) greater than that from spinach (n = 8), based on data from feces compared with 1.7 times (interval, 0.9, 3.1) based on data from serum.

Biological Availability↗
PubMed2003

Fast electrical lysis of cells for capillary electrophoresis.

In the past decade, capillary electrophoresis has demonstrated increasing utility for the quantitative analysis of single cells. New applications for the analysis of dynamic cellular properties demand sampling methods with sufficient temporal resolution to accurately measure these processes. In particular, intracellular signaling pathways involving many enzymes can be modulated on subsecond time scales. We have developed a technique to rapidly lyse an adherent mammalian cell using a single electrical pulse followed by efficient loading of the cellular contents into a capillary. Microfabricated electrodes were designed to create a maximum voltage drop across the flattened cell's plasma membrane at a minimum interelectrode voltage. The influence of the interelectrode distance, pulse duration, and pulse strength on the rate of cell lysis was determined. The ability to rapidly lyse a cell and collect and separate the cellular contents was demonstrated by loading cells with Oregon Green and two isomers of carboxyfluorescein. All three fluorophores were detected with a separation efficiency comparable to that of standards. Parallel comparison of electrical lysis to that produced by a laser-based lysis system revealed that the sampling efficiencies of the two techniques were comparable. Rapid cell lysis by an electrical pulse may increase the application of capillary electrophoresis to the study of cellular dynamics requiring fast sampling times.

Animals↗