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Biomedical subjects

Y Du

Publications and source records attributed to Y Du.

At least 19 recordsLinked to original sources
PubMed2006

cDNA microarray analysis of gene expression in Brassica napus treated with oligochitosan elicitor.

An oilseed rape (Brassica napus H) cDNA microarray containing 8095 expressed sequence tags (ESTs) was used to analyze the B. napus gene expression changes elicited by oligochitosan. Transcript levels for 393 genes were altered twofold or more in oligochitosan-treated seedlings compared to control seedlings. Of the 393 genes, 257 were repressed and 136 were induced. Semi quantification RT-PCR of eight of these 393 genes confirmed the microarray results. These 393 genes were involved in different processes and had different functions including defense, primary metabolism, transcription, and signal transduction etc. Some of these genes were elicited by various pathogen-related or stress stimuli, and others were regulated by plant growth regulators like auxin and gibberellin. These manifested complicated interactions of oligochitosan and phytohormones. An important jasmonic acid (JA) synthase (2-oxophytodienoate-10,11-reductase) gene, a JA-mediated defense required kinase ATMPK4-homolog gene, an ethylene receptor gene, and two ethylene responsive element binding protein (EREBP) genes were induced by oligochitosan, suggesting that oligochitosan activated the plant self-defense through JA/ET signaling pathway.

Brassica napus↗
PubMed2006

Isolation of a novel Ser/Thr protein kinase gene from oligochitosan-induced tobacco and its role in resistance against tobacco mosaic virus.

Oligochitosan induces defense responses to pathogenic microbes in a wide variety of plants by acting as an elicitor. In the present study, mRNA differential display was used to investigate oligochitosan-induced transcriptional activation of defense-related genes. Accordingly, a novel Ser/Thr protein kinase gene was isolated and designated as oligochitosan-induced protein kinase (oipk). Molecular cloning showed that oipk contains six introns interrupted by seven exons. The open reading frame (ORF) of the gene is 1848 bp, which encodes a putative protein of 615 amino acids with the predicted molecular mass of 70.96 kDa and a pI of 6.32. A plant oipk antisense expression vector was constructed and transformed into tobacco by Agrobacterium tumefaciens. Decreased phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) activity and decreased resistance to tobacco mosaic virus (TMV) were observed in transgenic tobacco. RT-PCR analysis revealed that oipk was expressed at high levels after oligochitosan induction in wild-type tobacco, but not in transgenic tobacco. These results indicated that oipk is involved in the signal pathway of oligochitosan-induced resistance in tobacco.

Amino Acid Sequence↗
PubMed2006

A characteristic pharmacological action of 'Yang-invigorating' Chinese tonifying herbs: enhancement of myocardial ATP-generation capacity.

In order to investigate the pharmacological basis of 'Yang-invigorating' action, the effect of oral treatment with the methanolic extract of 'Yang-invigorating' herbs on ATP-generation capacity was examined, using heart homogenates prepared from herb-pretreated mice. Tonifying (i.e., health-promoting) herbs of other functional categories were also included for comparison. The results indicated that 'Yang-invigorating' Chinese tonifying herbs could invariably enhance myocardial ATP-generation capacity, with the extent of stimulation varying among the herbs. In contrast, 'Yin-nourishing' herbs either did not stimulate or even decreased myocardial ATP-generation capacity. While 'Qi-invigorating' herbs produced variable effects on myocardial ATP-generation capacity, most of the 'blood-enriching' herbs did not cause any significant changes. The results obtained from studies using myocardial mitochondrial fractions isolated from herb-pretreated mice suggest that 'Yang-invigorating' herbs might speed up ATP generation by increasing mitochondrial electron transport. The ensemble of results has provided evidence for the first time to support the pharmacological basis of 'Yang invigoration' in Chinese medicine.

Adenosine Triphosphate↗
PubMed2006

Photodynamic therapy increases brain edema and intracranial pressure in a rabbit brain tumor model.

The objective of this study was to evaluate the effect of a single photodynamic therapy (PDT) on brain edema and intracranial pressure (ICP) in a rabbit model of brain tumor. A total of 57 adult New Zealand rabbits were assigned to 3 groups: the PDT group, the tumor group, and the tumor plus PDT group. Rabbits in the PDT group (n = 9) received PDT but no tumor implantation; rabbits in the tumor group (n = 18) received VX2 carcinoma implantation but no PDT; rabbits in the tumor plus PDT group (n = 30) received tumor implantation with subsequent PDT 16 days later. Brain edema and ICP levels were then evaluated. We found that ICP in the PDT group was 7.43 +/- 0.50 mmHg. After tumor implantation, ICP increased rapidly (18.43 +/- 1.10 mmHg, 21 days later). PDT alone did not increase ICP, but compared with that in the tumor group, ICP increased significantly in the tumor plus PDT group (9.55 +/- 1.32 vs. 13.31 +/- 1.13 mmHg, p < 0.01) 24 hours after treatment. Brain water content in the tumor group increased rapidly after tumor implantation. PDT again increased perineoplastic brain edema 24 hours after treatment (81.09 +/- 0.97% vs. 78.32 +/- 0.49%, p < 0.01). It should be noted that PDT alone did not induce brain edema. In conclusion, PDT causes transient brain edema and increases ICP in a rabbit brain tumor model.

Animals↗
PubMed2006

An apparatus for studying the response of cultured endothelial cells to stresses.

In order to simulate the hemodynamic environment of human arteries in vivo, we designed a laminar flow apparatus which can precisely simulate the normal stress and shear stress to which cultured endothelial cells are exposed. Under both normal and abnormal physiological conditions, this apparatus can accurately control and adjust the values of normal stress and shear stress and the frequency of pulse waves, as well as the amplitude of pulsatile flow. This in vitro apparatus provides an experimental platform for studying the response of the biological characteristics of cultured endothelial cells in a hemodynamic environment.

Blood Flow Velocity↗
PubMed2006

Chemically assisted handmade enucleation of porcine oocytes.

The purpose of our work was to find an efficient and reliable chemically assisted procedure for enucleation of porcine oocytes connected to the handmade cloning (HMC) technique without the potentially harmful chromatin staining and ultraviolet (UV) irradiation for cytoplast selection. After 41-42 h in vitro maturation, porcine oocytes were incubated with 0.4 microg/mL demecolcine for 45 min. Subsequently, the cumulus cells were removed and zonae pellucidae were partially digested. Oocytes with extrusion cones or oocytes only with polar body (PB) were subjected to oriented bisection. Less than half of the cytoplasm with the extrusion cone or adjacent to the PB was removed with a microblade. The remaining putative cytoplasts, containing the major part of the cytoplasm, were used as recipients for reconstruction with porcine fetal fibroblasts as nuclear donors. The overall efficiency achieved with chemically assisted enucleation was higher compared to oriented bisection without demecolcine incubation (90 +/- 3% vs. 81 +/- 4%, respectively; mean +/- absolute deviation [AD]). Reconstructed and activated embryos were cultured in vitro for 7 days. Fusion, cleavage and blastocyst rates were 87 +/- 7%, 97 +/- 6%, and 28 +/- 9%, respectively. These rates are at least as good as those achieved with normal HMC (81 +/- 4%, 87 +/- 8%, and 21 +/- 9%, respectively). For traditional, micromanipulator-based cloning, fusion and blastocyst rates were similar (81 +/- 10% and 21 +/- 6%, respectively), but the cleavage rate was lower (69 +/- 9%). In conclusion, chemically assisted handmade enucleation seems to be a simpler and potentially superior alternative to more conventional methods used for somatic cell nuclear transfer in pigs.

Animals↗
PubMed2006

Synthetic oligosaccharide stimulates and stabilizes angiogenesis: structure-function relationships and potential mechanisms.

To determine the proangiogenesis effect of series of saccharides and a synthetic oligosaccharide and potential mechanisms, an in vitro 3-dimensional endothelial cell sprouting (3D-ECS) assay and the chick chorioallantoic membrane (CAM) model were used. We demonstrated that a sulfated oligosaccharide significantly promotes the endothelial capillary network initiated by vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF). Furthermore, although the capillary network initiated by VEGF and b-FGF lasts no more than 7 days, addition of a sulfated oligosaccharide significantly amplifies angiogenesis and stabilizes the capillary network of new blood vessels. In the CAM model, sulfated oligosaccharide also stimulated angiogenesis. In both the CAM and the 3D-ECS assay, structure-function studies reveal that increased saccharide chain length up to the hexa- to decasaccharide show optimal proangiogenesis efficacy. In addition, the sulfation and molecular shape (branched vs linear) of oligosaccharide are important for sustained proangiogenesis efficacy. Data indicate that chemically defined synthetic oligosaccharides can play an important role in regulation of capillary structure and stability, which may contribute to future advances in therapeutic angiogenesis. The proangiogenesis efficacy of an oligosaccharide is mediated via integrin alphavbeta3 and involves mitogen-activated protein kinase signaling mechanisms.

Animals↗
PubMed2005

Efficient in vitro production of porcine blastocysts by handmade cloning with a combined electrical and chemical activation.

The purpose of our work was to establish an efficient protocol for activation of porcine cytoplast-fibroblast constructs produced by the handmade cloning technique. Firstly, we investigated a combined electrical and chemical activation protocol for parthenogenetic development of in vitro matured zona-free oocytes. Oocytes were activated by one 80 micros pulse and subsequently cultured in cytochalasin B and cycloheximide. Developmental rates of blastocysts from activated oocytes were 49+/-1 and 40+/-2%, when using one 80 micros pulse of 0.85 or 1.25 kV/cm, respectively. The activation procedure was further confirmed by a simultaneous re-fusion and activation of bisected oocytes, resulting in a blastocyst rate of 41+/-8%. Secondly, the activation protocol was applied in the handmade cloning technique. In vitro matured zona-free porcine oocytes were bisected and halves containing no chromatin, i.e. the cytoplasts, were selected. Reconstructed embryos were produced by a two-step fusion procedure. At the first step, one cytoplast was fused to one fibroblast by one 80 micros pulse of 1.25 kV/cm. After 1h, the cytoplast-fibroblast pair and another cytoplast were fused and activated simultaneously by one 80 micros pulse of 0.85 kV/cm, and subsequently cultured in cytochalasin B and cycloheximide. The development of reconstructed embryos to the blastocyst stage was in average 21+/-4%, and total blastocyst cell counts were in average 48+/-3. Thus, the combined electrical and chemical activation procedure resulted in efficient blastocyst development in the handmade cloning technique.

Animals↗
PubMed2005

Protection against Helicobacter pylori infection in the Mongolian gerbil after prophylactic vaccination.

Vaccines against Helicobacter pylori could circumvent the problem of increasing antibiotic resistance. They would be particularly useful in developing countries, where re-infection rates are high following standard eradication regimes. The Mongolian gerbil is a good model for H. pylori infection, as the gastric pathology induced by infection is similar to that in humans. The H. pylori-induced inflammatory response in gerbils is considerably greater than in murine models. The aim of this study was to determine if gerbils could be vaccinated against H. pylori. Mongolian gerbils were vaccinated orally with an H. pylori whole cell sonicate preparation and cholera toxin adjuvant. Vaccinated gerbils and controls were challenged with the autologous H. pylori strain 42GX. All infection, and cholera toxin, control gerbils were H. pylori positive 6 weeks post-challenge. By contrast, a significant degree of protection was demonstrated in vaccinated gerbils. Only two of 10 of gerbils were H. pylori positive (P<0.001). Protection was associated with increased serum H. pylori IgG antibodies. Protected gerbils had histologically normal gastric mucosa and, in contrast to mice, no post-immunisation gastritis was evident. In the control groups, the degree of inflammation was variable, with some of the animals having corpus gastritis and corpus mucous metaplasia. The levels of gastric IL-12p40 and IFNgamma transcripts were significantly decreased in vaccinated animals compared to infection and cholera toxin controls (P<0.01). Gastric IL-10 and TGFbeta transcripts were found only at relatively low levels. These results demonstrate that Mongolian gerbils can be successfully vaccinated against H. pylori and protected from H. pylori-induced pathology.

Animals↗
PubMed2005

Obstruction identification in branching compliant tubes with application to airway passages.

A feasibility study for occlusion identification in a branched tube-like structure using the frequency spectrum of the acoustic input impedance determined at the main entrance to the network is presented. The frequency spectra for one- and two-generation models are generated to study the effect of an occlusion in one of the branches on the spectra with an application to the trachea and the first two generations of the airways. The result demonstrates that the input impedance resonant frequencies can map the location, severity and degree of an obstruction in any of the considered branches.

Animals↗
PubMed2005

Fast modelling of the collimator-detector response in Monte Carlo simulation of SPECT imaging using the angular response function.

Interactions of incident photons with the collimator and detector, including septal penetration, scatter and x-ray fluorescence, are significant sources of image degradation in applications of SPECT including dual isotope imaging and imaging using radioisotopes that emit high- or medium-energy photons. Modelling these interactions using full Monte Carlo (MC) simulations is computationally very demanding. We present a new method based on the use of angular response functions (ARFs). The ARF is a function of the incident photon's direction and energy and represents the probability that a photon will either interact with or pass through the collimator, and be detected at the intersection of the photon's direction vector and the detection plane in an energy window of interest. The ARFs were pre-computed using full MC simulations of point sources that include propagation through the collimator-detector system. We have implemented the ARF method for use in conjunction with the SimSET/PHG MC code to provide fast modelling of both interactions in the patient and in the collimator-detector system. Validation results in the three cases studied show that there was good agreement between the projections generated using the ARF method and those from previously validated full MC simulations, but with hundred to thousand fold reductions in simulation time.

Algorithms↗
PubMed2005

Minocycline prevents gentamicin-induced ototoxicity by inhibiting p38 MAP kinase phosphorylation and caspase 3 activation.

Aminoglycosides are commonly used antibiotics that often induce ototoxicity leading to permanent hair cell loss and hearing impairment. We hereby examined whether minocycline protects hair cells from gentamicin-induced hair cell damage. Two millimolar gentamicin significantly induced outer hair cell damage and the addition of minocycline to gentamicin-treated explants significantly increased hair cell survival in a dose-dependent manner. Additionally, we demonstrated that gentamicin induced p38 MAPK phosphorylation, cytochrome c release, and caspase 3 activation in these cells and these remarkable changes were blocked by minocycline treatments. Furthermore, we showed that the inhibitor of p38 MAPK or the inhibitor of caspase 3 only partially blocked gentamicin-induced hair cell damage, and the pretreatment of explants with the inhibitor of p38 MAPK and the inhibitor of caspase 3 together exerted a synergic protective effect against gentamicin-induced hair cell damage. Our results suggest that minocycline blocks gentamicin-induced hair cell loss possibly by inhibition of three mechanisms: p38 MAPK phosphorylation, cytochrome c release, and caspase 3 activation. This finding may explain why minocycline has protective activity in a variety of apoptotic models. Therapeutic intervention by using minocycline or related drugs may be a novel means for preventing inner ear injury following the use of aminoglycoside.

Animals↗
PubMed2005

High overall in vitro efficiency of porcine handmade cloning (HMC) combining partial zona digestion and oocyte trisection with sequential culture.

We investigated the in vitro developmental competence of porcine embryos produced from in vitro matured (IVM) oocytes by improved HMC and parthenogenetic activation (PA). Embryos were cultured in a modified North Carolina State University (NCSU37) medium. Firstly, we compared the developmental competence between oocytes from sows and gilts by zona-intact (ZI) and zona-free (ZF) PA. Significantly higher (p < 0.05) blastocyst rates were obtained from sow oocytes (42 +/- 4% for ZF and 55 +/- 6% for ZI) than gilt oocytes (20 +/- 2% for ZF and 26 +/- 5% for ZI). Secondly, sow oocytes were used to establish the modified HMC that was based on a modified enucleation with partial zona digestion and trisection of porcine oocytes and the use of three cytoplasts and one somatic cell for embryo reconstruction. In vitro fertilization (IVF) and in parallel ZF PA were used as the control systems. After oocyte trisection, >90% of oocyte fragments were recovered, resulting in an average of 37 reconstructed embryos from 100 oocytes. Blastocyst rates of HMC, IVF, and ZF PA embryos were 17 +/- 4%, 30 +/- 6%, and 47 +/- 4%, respectively. Our results prove that HMC in pigs may result in high in vitro efficiency up until the blastocyst stage. In vivo developmental competence will be confirmed in embryo transfer experiments.

Animals↗
PubMed2004

Pharmacological basis of 'Yin-nourishing' and 'Yang-invigorating' actions of Cordyceps, a Chinese tonifying herb.

Cordyceps sinensis (Berk.) Sacc. (Cordyceps), a popular Chinese tonifying herb, was revered for being both 'Yin-nourishing' and 'Yang-invigorating' in Chinese medicine. In order to establish the pharmacological basis for the 'Yin-nourishing' and 'Yang-invigorating' action of Cordyceps, the effects of wild and cultured Cordyceps on concanavalin A (Con A)-stimulated splenocytes, an in vitro bioassay for 'Yin-nourishment', and myocardial ATP generation capacity, an ex vivo bioassay for 'Yang-invigoration', were investigated in mice. The results indicated that methanolic extracts of wild and cultured Cordyceps enhanced both the Con A-stimulated splenocyte proliferation in vitro and myocardial mitochondrial ATP generation ex vivo in mice, with no significant difference in potency of action between the two types of Cordyceps. While the immuno-potentiating effect was associated with the increase in interleukin II production, the stimulation of myocardial ATP generation was paralleled by an enhancement in mitochondrial electron transport. When compared with typical 'Yin' and 'Yang' tonifying Chinese herbs, Cordyceps was found to possess both 'Yin-nourishing' and 'Yang-invigorating' activities, with a lower potency in both modes of action. The pharmacological characterization of Cordyceps by means of contemporary bioassays is consistent with the time-honored clinical observation from Chinese herbalists.

Adenosine Triphosphate↗
PubMed2004

Correlating lamotrigine serum concentrations with tolerability in patients with epilepsy.

OBJECTIVE: To correlate lamotrigine (LTG) serum concentrations (levels) with tolerability in patients with epilepsy. METHODS: The charts of 811 outpatients with epilepsy who had received LTG and were seen at the Columbia Comprehensive Epilepsy Center after January 1, 2000, were reviewed. Data gathered included levels, dosage, duration of use, concomitant antiepileptic drugs (AEDs), clinical toxicity, specific side effects, and efficacy. Rates of toxicity, specific side effects, and efficacy were calculated and correlated with serum levels. RESULTS: In total, 3,731 LTG levels were recorded. A regimen was categorized as toxic if the patient experienced side effects that led to a dosage change or discontinuation of LTG. Of 3,919 AED regimens, 9.4% were toxic and 30.7% of patients had at least one toxic regimen. Toxicity increased with increasing LTG levels (p < 0.0001): With levels <5.0 microg/mL, 7% of patients were toxic; with levels of 5 to 10 microg/mL, 14%; with 10 to 15 microg/mL, 24%; with 15 to 20 microg/mL, 34%; and with >20 microg/mL, 59%. The correlation between levels and tolerability was independent of concurrent medication. Increasing efficacy, as measured by seizure freedom for a 6-month period, occurred up to levels of >20 microg/mL. CONCLUSIONS: There is a correlation between LTG serum level and tolerability, independent of the use of other AEDs. Adverse effects requiring a dose change are uncommon with the most frequently encountered LTG concentrations (<10 microg/mL) and occur in only 7.4% of patients at levels obtained during the majority of clinical trials (<5 microg/mL). An initial target range of 1.5 to 10 microg/mL is suggested, though higher levels, up to >20 microg/mL, are often tolerated and can lead to additional efficacy in refractory patients.

Anticonvulsants↗
PubMed2004

A yang-promoting Chinese herbal suppository preparation enhances the antioxidant status of red cells in male human subjects.

In the 16-week pilot study, the effect of a Yang-promoting Chinese herbal suppository preparation (VI-28) on the red cell antioxidant status was examined in 31 healthy male subjects aged 41-66 years old. VI-28 treatment for 12 weeks (one suppository (0.3 g) daily for week 1-4; one every 2 days for week 5-8; one every 3 days for week 9-12) produced a time/dose-dependent alteration in red cell antioxidant status. The VI-28-induced change is characterized by a slight depletion in cellular reduced glutathione (GSH) level and a decrease in susceptibility to peroxide-induced lipid peroxidation as well as increases in catalase (CAT) and Cu-Zn-superoxide dismutase (SOD) activities. While a reversal trend of change was observed in cellular GSH level, the susceptibility to lipid peroxidation as well as the CAT activity after the cessation of treatment for 4 weeks, the SOD activity exhibited a protracted increase. The results indicate that VI-28 treatment enhances red cell antioxidant status in male subjects. The beneficial effect of VI-28 treatment on red cells may re fl ect a corresponding change in antioxidant status of peripheral tissues.

Adult↗