Biomedical subjects

X Y Wu

Publications and source records attributed to X Y Wu.

At least 19 recordsLinked to original sources

PubMed2006

Characterization of Cryptocaryon irritans isolates from marine fishes in Mainland China by ITS ribosomal DNA sequences.

Seven isolates of Cryptocaryon irritans from different host species and geographical locations in Mainland China were characterized by the first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA) using two isolates of Ichthyophthirius multifiliis for comparative purposes. The rDNA region including the ITS-1, 5.8S, ITS-2, and flanking 18S and 28S sequences were amplified by polymerase chain reaction and the amplicons were sequenced directly. The ITS-1, 5.8S, and ITS-2 sequences were 129, 160, and 190 bp in length, respectively, for all seven C. irritans isolates, whereas the corresponding sequences for the two I. multifiliis isolates were 142, 153, and 194 bp, respectively. While sequence variation among the seven C. irritans isolates ranged from 0 to 1.6% in both the ITS-1 and ITS-2, and the two I. multifiliis isolates differed by 1.4% in the ITS-1 and 1.0% in the ITS-2; C. irritans differed from I. multifiliis by 57.1-60.9% in the ITS-1 and 79.4-83.0% in the ITS-2, indicating that ITS sequences provide reliable genetic markers for the identification and differentiation of the two species. Phylogenetic analysis using the sequence pairwise-distance data using the neighbor-joining method inferred that the seven C. irritans isolates from Mainland China and two other isolates (T.A and Aus.C) from other countries clustered together to show monophyly, which could be readily distinguished from the other monophyletic group all from other regions. Therefore, ITS sequence data and phylogenetic analysis provided strong support that C. irritans isolates from Mainland China represent a single species. The definition of genetic markers in the ITS rDNA provide opportunities for studying the ecology and population genetic structures of the C. irritans from Mainland China and elsewhere and is also relevant to the diagnosis and control of fish diseases they cause.

Animals↗

PubMed2006

The radiation of Haliotrema (Monogenea: Dactylogyridae: Ancyrocephalinae): molecular evidence and explanation inferred from LSU rDNA sequences.

The D1-D2 domains of LSU rDNA were used to reconstruct the phylogenetic relationships within the Ancyrocephalinae (Monogenea: Dactylogyridae) utilizing maximum-parsimony (MP), maximum-likelihood (ML), minimum evolution (ME) and neighbour-joining (NJ) methods. A total of 32 monogenean taxa were examined in the present study, including 9 Haliotrema species and 13 other species representing the Ancyrocephalinae, 4 Thaparocleidus species representing the Ancylodiscoididae, and 6 species representing the Diplectanidae which were used as multiple outgroups. All 4 analyses (i.e. MP, ML, ME and NJ) inferred the same interrelationship pattern: (Diplectanidae, (Ancylodiscoididae, Dactylogyridae)) with high bootstrap support. However, 9 Haliotrema species were dispersed to form 4 clades together with species from other genera, indicating the apparent non-monophyly of Haliotrema. Three major groups were defined based on reconstructed phylogenetic trees to explain the radiation of Haliotrema species. The morphology of the reproductive organ, particularly the male copulatory organ (MCO), was discussed to further understand the formation of each group. (1) Results of the present study indicated an intimate relationship among Metahaliotrema (2 species), Protogyrodactylus (4 species) and Haliotrema (2 of 9 species), and notably, all these species share vagina-absence. (2) Based on the present molecular analyses and the morphological characters of the MCO, we propose to transfer H. spirotubiforum and the undetermined Haliotrema sp. ZHDDb to Euryhaliotrema as new combinations. (3) We propose to erect a new genus to accommodate the Haliotrema species with horn-like shaped MCO. Taxonomic implications of the present molecular phylogenetic analyses are discussed. A wider range of taxa and more DNA markers displaying various evolutionary rates should be used to estimate phylogenetic relationships among species within the Ancyrocephalinae and Ancylodiscoididae in further studies.

Animals↗

PubMed2006

Verapamil modulates LPS-induced cytokine production via inhibition of NF-kappa B activation in the liver.

OBJECTIVE: To investigate the effect of verapamil on Lipopolysaccharide (LPS)-induced cytokines [tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-10 (IL-10)] and nuclear factor kappa B (NF-kappa B) in the liver. METHODS AND MATERIALS: Adult male Sprague-Dawley rats were randomly divided into seven groups of eight rats each: control rats treated with saline (0.9 % NaCl); rats treated with saline and then challenged intraperitoneally with LPS (10 mg/kg); rats treated intraperitoneally with different levels of verapamil (1, 2.5, 5, 10 mg/kg) and then challenged with LPS (10 mg/kg); and rats treated only with verapamil (10 mg/kg). TNF-alpha, IL-6, IL-10 and NF-kappa B in the liver tissues were investigated as well as the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) one hour after LPS injection. RESULTS: LPS alone stimulated production of TNF-alpha, IL-6 and IL-10, and activated NF-kappa B in the liver. Pretreatment with verapamil before LPS challenge reduced acute liver injury, down-regulated production of LPS-induced pro-inflammatory cytokines (TNF-alpha and IL-6), up-regulated production of anti-inflammatory cytokines (IL-10) and inhibited NF-kappa B activation in the liver in a dose-dependent manner. CONCLUSION: Verapamil can attenuate acute liver injury by down-regulating the production of TNF-alpha and IL-6 and up-regulating IL-10 in the liver, possibly via inhibition of NF-kappa B.

Animals↗

PubMed2005

Expression of survivin and bax/bcl-2 in peroxisome proliferator activated receptor-gamma ligands induces apoptosis on human myeloid leukemia cells in vitro.

The present study was undertaken to investigate the mechanisms of peroxisome proliferator activated receptor-gamma (PPAR-gamma) ligand-induced apoptosis on human myeloid leukemia K562 and HL-60 cell lines. The results revealed that both 15-deoxy-delta(12,14)-prostaglandin J2 (15d-PGJ2) and troglitazone (TGZ) have significant anti-proliferation- and apoptosis-inducing effects on these two kinds of leukemia cells. Marked morphological changes of cell apoptosis including condensation of chromatin and nuclear fragmentation were observed clearly using Wright's and Hoechst 33258 staining. Reverse transcription-PCR and western blot analyses demonstrated that both survivin and bcl-2 expression were downregulated markedly, while bax expression was upregulated concurrently when apoptosis occurred. We therefore conclude that 15d-PGJ2 and TGZ have significant apoptosis effects on K562 and HL-60 cells in vitro, and that upregulation of bax as well as downregulation of survivin and bcl-2 expression may be the important apoptosis-inducing mechanisms. The results suggest that PPAR-gamma ligands may serve as potential therapeutic agents for both acute and chronic myeloid leukemia.

Antineoplastic Agents↗

PubMed2005

Modeling of dispersed-drug release from two-dimensional matrix tablets.

A mathematical model was developed and analytical solutions were obtained for dispersed-drug release from two-dimensional matrix tablets in a perfect sink. This model can be used to describe kinetics of solute release from matrices with isotropic or anisotropic properties. Moving boundaries of dispersed-drug in both radial and axial directions and release kinetics were predicted by the model. Various factors influencing release kinetics were analyzed including the ratio of initial solute loading (C0) to solute solubility (Cs), the anisotropy of the matrix and the aspect ratio of tablet radius to the half-thickness. The model is also applicable to 1-D planar or 1-D cylindrical geometries when R/H is larger than 100 or smaller than 0.01.

Data Interpretation, Statistical↗

PubMed2005

Neurochemical phenotype of vagal afferent neurons activated to express C-FOS in response to luminal stimulation in the rat.

UNLABELLED: The vagus nerve conveys meal-induced primary afferent responses to the brainstem. Electrophysiological studies indicate that luminal stimuli such as osmolarity and the digestion products of carbohydrates elicit powerful vagal nodose neuronal responses by activating serotonin 3 (5-hydroxytryptamine-3, 5-HT3) receptors on intestinal mucosal afferent fibers. To characterize the neurochemical phenotype of neurotransmitters in vagal nodose neurons that are activated by luminal stimulation, we examined c-fos protein (c-Fos) expression in response to luminal stimulation in conscious rats. A double-labeling technique using antisera to glutamate (Glu), substance P (SP), calcitonin gene-related peptide (CGRP), and somatostatin (SS) was used to determine the neurochemical profile of c-Fos-positive neurons. c-Fos immunoreactivity was insignificant in vehicle-treated rats. Luminal perfusions of NaCl (500 mOsm), tap water (5 mOsm), maltose (300 mmol/l), and 5-HT (10(-5) mol/l) each elicited a significant increase in the number of cells expressing c-Fos. Chronic vagotomy eliminated an increase in nodose neuronal c-Fos expression, and the 5-HT3 receptor antagonist granisetron significantly reduced it. Glu-, SP-, and CGRP-containing neurons represented 28%, 53%, and 19%, respectively, of the total population of nodose neurons. Few neurons contained SS. Double-labeling studies revealed that of the c-Fos-positive neurons responsive to hypertonic NaCl, 52%, 41%, and 3% exhibited immunoreactivity for Glu, SP, and CGRP, respectively. Of those responsive to tap water, 47%, 50%, and 4% exhibited immunoreactivity for Glu-, SP- and CGRP, respectively. In addition, 44%, 38%, and 8% of 5-HT-stimulated and 30%, 32%, and 5% of maltose-stimulated c-Fos-positive neurons exhibited, respectively, Glu, SP, and CGRP immunoreactivity. The few neurons that contained SS did not express c-Fos. CONCLUSIONS: Vagal primary afferent neurons that respond to 5-HT-dependent luminal stimuli, such as hyperosmolarity and maltose, contain mainly Glu and SP. These neurons appear to play an important role in the mediation of the vago-vagal reflex elicited by luminal stimuli.

Animals↗

PubMed2005

Molecular and morphological evidence indicates that Pseudorhabdosynochus lantauensis (Monogenea: Diplectanidae) represents two species.

Sequences of the first internal transcribed spacer (ITS-1) and the D1-D3 domains of the large subunit (LSU) of the ribosomal DNA (rDNA) were determined for multiple specimens of 4 operational taxonomic units (OTUs) of the monogenean, Pseudorhabdosynochus lantauensis. OTUs were defined based on their collecting localities, host and/or morphological characteristics. All P. lantauensis specimens of one group (OTUs 1 and 3) differed in their sequences of the ITS-1 and partial LSU rDNA when compared with specimens of a second group (OTUs 2 and 4) by 12% and 2%, respectively. Results of the phylogenetic analyses of the LSU rDNA sequence data showed total (100%) bootstrap support for the separation of P. lantauensis into 2 distinct clades. At least 11 of the 18 nucleotide differences in the LSU sequence between the two P. lantauensis clades were derived (i.e. autapomorphic) characters when the morphologically distinct species, P. epinepheli and P. coioidesis, were used as outgroups. Furthermore, there were several autapomorphic character states for each P. lantauensis clade. This provides sufficient evidence to reject the null hypothesis that P. lantauensis represents a single species. Morphological and morphometric differences between these two clades provided additional strong support for the separation of P. lantauensis into two species. These two parasite species were found to co-exist on one of the two species of serranid fish (i.e. Epinephelus coioides) examined in the South China Sea (Guangdong Province, China).

Animals↗

PubMed2005

Oridonin-induced apoptosis in leukemia K562 cells and its mechanism.

Oridonin, an extract from the Chinese herb Rabdosia rubescens, is currently one of the most important traditional Chinese herbal medicines. Recently oridonin has been reported to have anti- tumor effects in a large variety of malignant diseases. In this study, we investigated the apoptotic inducing effect of oridonin in leukemia K562 cells and its mechanism. Cell growth inhibition was measured using a microculture tetrazolium assay, apoptosis was measured by flow cytometry and electron microscopy as well as by DNA fragmentation analysis. Telomerase activity was measured by TRAP-enzyme- linked immunosorbent assay, and the expression of Bcl-2 and Bax proteins was detected by western blot analysis. The results showed that oridonin could inhibit the proliferation and induce apoptosis on leukemia K562 cells remarkably. Telomerase activity as well as Bcl-2 expression was down- regulated, while Bax expression was up-regulated concurrently, when apoptosis ocurred. We therefore conclude that oridonin demonstrated anti-proliferative and apoptosis-inducing effects on K562 cells in vitro, and that changes in bcl-2 and bax protein levels as well as telomerase activity may play an important role in its mechanism of action.

Antineoplastic Agents↗

PubMed2004

Serotonin and cholecystokinin synergistically stimulate rat vagal primary afferent neurones.

Recent studies indicate that cholecystokinin (CCK) and serotonin (5-hydroxytryptamine, 5-HT) act via vagal afferent fibres to mediate gastrointestinal functions. In the present study, we characterized the interaction between CCK and 5-HT in the vagal primary afferent neurones. Single neuronal discharges of vagal primary afferent neurones innervating the duodenum were recorded from rat nodose ganglia. Two groups of nodose ganglia neurones were identified: group A neurones responded to intra-arterial injection of low doses of cholecystokinin octapeptide (CCK-8; 10-60 pmol); group B neurones responded only to high doses of CCK-8 (120-240 pmol), and were also activated by duodenal distention. CCK-JMV-180, which acts as an agonist in high-affinity states and as an antagonist in low-affinity states, dose dependently stimulated group A neurones, but inhibited the effect of the high doses of CCK-8 on group B neurones. Duodenal perfusion of 5-HT evoked dose-dependent increases in nodose neuronal discharges. Some neurones that responded to 5-HT showed no response to either high or low doses of CCK-8. A separate group of nodose neurones that possessed high-affinity CCK type A (CCK-A) receptors also responded to luminal infusion of 5-HT. Further, a subthreshold dose of CCK-8 (i.e. 5 pmol) produced no measurable electrophysiological effects but it augmented the neuronal responses to 5-HT. This potentiation effect of CCK-8 was eliminated by CR 1409. From these results we concluded that the vagal nodose ganglion contains neurones that may possess only high- or low-affinity CCK-A receptors or 5-HT3 receptors. Some neurones that express high-affinity CCK-A receptors also express 5-HT3 receptors. Pre-exposure to luminal 5-HT may augment the subsequent response to a subthreshold dose of CCK.

Action Potentials↗

PubMed2004

Theoretical analysis of drug release into a finite medium from sphere ensembles with various size and concentration distributions.

Release kinetics for heterogeneous sphere ensembles with a dissolved drug, i.e., initial drug loading below or equal to the drug solubility in the matrix, in a finite external medium was modeled with consideration of heterogeneity among and within spheres. Numerical solutions were obtained using the finite element method for sphere ensemble with normal or log-normal distribution of particle size or initial drug loading among spheres. Exact series solutions were derived for ensembles with various initial loading distributions within spheres, namely linear, quadratic, sigmoidal and uniform distribution, using their mean or average radii. Simplified solutions retaining only one term of the series for non-uniform distributions and three terms for uniform distribution were suggested because of their good approximation to the exact solution. The results of finite element analysis showed that the release rate of an ensemble decreased with increasing standard deviation of particle size. Using weight-average radii in the exact solution gave a prediction of release profile closer to that from the actual size distribution than using mean radii. The three non-uniform loading patterns within spheres all showed reduced initial burst and release rate, leading to more steady release rates than uniform loading, among which the sigmoidal distribution offered the best near-zero order release. Non-uniform initial loading among spheres seemed to have insignificant influence on the release profiles. The volume ratio of liquid to a sphere ensemble played an important role in release kinetics. The derived analytical solutions are applicable to multiple spheres or a single sphere in a finite medium or in a perfect sink.

Algorithms↗

PubMed2004

Assessment of perfusion by dynamic contrast-enhanced imaging using a deconvolution approach based on regression and singular value decomposition.

The assessment of tissue perfusion by dynamic contrast-enhanced (DCE) imaging involves a deconvolution process. For analysis of DCE imaging data, we implemented a regression approach to select appropriate regularization parameters for deconvolution using the standard and generalized singular value decomposition methods. Monte Carlo simulation experiments were carried out to study the performance and to compare with other existing methods used for deconvolution analysis of DCE imaging data. The present approach is found to be robust and reliable at the levels of noise commonly encountered in DCE imaging, and for different models of the underlying tissue vasculature. The advantages of the present method, as compared with previous methods, include its efficiency of computation, ability to achieve adequate regularization to reproduce less noisy solutions, and that it does not require prior knowledge of the noise condition. The proposed method is applied on actual patient study cases with brain tumors and ischemic stroke, to illustrate its applicability as a clinical tool for diagnosis and assessment of treatment response.

Algorithms↗

PubMed2003

Modeling and analysis of dispersed-drug release into a finite medium from sphere ensembles with a boundary layer.

Mathematical models were developed and analytical solutions were derived for describing kinetics of dispersed-drug release into a finite external medium from multi-particulate systems, such as ensembles of matrix spheres and microcapsules with a diffusion boundary layer. The solutions can be used to compute profiles of the moving boundary of a dispersed drug and the amount of drug released for multiparticulate ensembles with various ratios of initial drug loading (C(0)) to drug solubility (C(s)) in a finite to infinite medium. They are also applicable to a single sphere without a boundary layer in a perfect sink. The determinants of release kinetics, such as the liquid volume, the initial drug loading, the boundary layer thickness, and the number of spheres in a population, were analyzed using the derived solutions. The effect of coating thickness and material on the release profiles of microcapsules was studied as well. Criteria were established for finding the conditions when drug release would stall due to saturation of the medium, which can be used to determine suitable liquid volume and time for refreshing the medium.

Capsules↗

PubMed2003

Simulation study of the effects of hypovolaemia on cardiovascular response to orthostatic stress.

To investigate the role played by hypovolaemia in the mechanism of orthostatic intolerance, a mathematical model was developed. The model consisted of seven sub-models that describe: the redistribution of blood induced by lower body negative pressure (LBNP); filling of the left ventricle; contracting of the left ventricle; interaction between the left ventricle and peripheral circulation; and baroreflex regulation. The model was evaluated using experimental data. Using the model, computer simulations were performed to investigate the effects of hypovolaemia on the cardiovascular response to LBNP. The simulation results indicated that, first, when the blood loss is less than 5%, blood pressure can be maintained in the normal range by the baroreflex regulatory mechanism, even with high LBNP application; secondly, when the blood loss is between 15 and 20%, heart rate and blood pressure can be kept in the normal range if LBNP is not applied, but blood pressure falls sharply with LBNP application; and, thirdly, when the blood loss is 25%, the cardiovascular system is in an unstable state (heart rate: 116 beat min (-1), systolic blood pressure: 97 mmHg; diastolic blood pressure: 77 mmHg), even without any LBNP, and becomes more unstable with LBNP. The simulation results support the hypothesis that hypovolaemia is a cause of orthostatic intolerance.

Adult↗

PubMed2002

Theoretical analyses of dispersed-drug release from planar matrices with a boundary layer in a finite medium.

Analytical solutions for the kinetics of dispersed-drug release from planar matrices with a boundary layer in a well-stirred finite external medium were derived in a general and a simplified form. The general solutions are applicable for a broad range of the ratio of initial drug loading to drug solubility (e.g. C(0)/C(s)> or =3) till all dispersed drug is dissolved, while the simplified solutions describe the entire release process for higher C(0)/C(s) ratios (e.g. C(0)/C(s)> or =10). As the C(0)/C(s) ratio increased, the general solutions approached the exact solution from the lower bound, and the simplified solution from the upper bound. This property could be useful to find the lower and upper bound of an exact solution for the sink condition without a boundary layer when it is unknown. The current solutions can cover more scenarios than the existing analytical and approximate solutions. The formulas, with explicit expressions, can be readily applied to analyze determinants of release kinetics, including volume of external medium, initial drug loading, and boundary layer thickness. With the criterion established for finding the conditions of drug saturation in a medium, minimal liquid volume and maximal time for refreshing the medium can be determined.

Algorithms↗

PubMed2001

[Analysis on three-year follow-up results of excimer laser photorefractive keratectomy in treatment for myopia and myopic astigmatism].

OBJECTIVE: To evaluate the efficacy of excimer laser photorefractive keratectomy(PRK) on myopia and myopia astigmatism. METHODS: PRK was performed with VISXC20/20 on 377 eyes of 209 patients. Treated eyes were divided into two groups, according to their conditions before operation: Group I included 238 eyes (-1.50 to -6.00 D); Group II, 139 eyes (-6.25 to -16.00 D). All patients were followed-up for more than three years. RESULTS: Percentages of uncorrected visual acuity (UCVA) > or = 10/20 and 20/20 were 99.6% and 85.3% in Group I, and 79.9% and 48.2% in Group II respectively. Percentage of diopter < +/- 1.00 in Group I was 94.5%, and 61.9% in Group II. The rate of corneal haze of grade 0 was 100% in Group I, and 98.6% in Group II, but corneal haze of grade 2 was found in 1.2% of eyes in Group II. The postoperative intraocular pressure (IOP) of all operated eyes was normal. CONCLUSION: The results suggest that excimer laser PRK is an effective method for treating myopia and myopic astigmatism, especially for low and moderate myopia.

Adolescent↗

PubMed2001

A study of doxorubicin loading onto and release from sulfopropyl dextran ion-exchange microspheres.

The objective of this study was to investigate various factors that influence doxorubicin (Dox) loading onto and release from sulfopropyl dextran ion-exchange microspheres (MS), and to evaluate the anticancer activity of the released drug in vitro. Dox was incorporated into the MS by incubating the MS with aqueous solutions of Dox at room temperature. The drug release was carried out at 37 degrees C in aqueous solutions containing NaCl with or without CaCl2. The kinetics of drug absorption and release, the amount of Dox released, and the stability of Dox after loading, freeze-drying, and release were determined by spectrophotometry. The cytotoxicity of Dox (the original drug or that released from MS) against murine EMT6 breast cancer cells was assessed using a clonogenic assay. An increase in the MS to drug ratio resulted in a higher absorption rate and a higher fraction of the drug extracted from the solution. The release rate and the equilibrium fraction of Dox released increased with a decrease in the initial amount of Dox loaded or an increase in the salt concentration. The addition of divalent ions (Ca2+) promoted drug release compared to NaCl alone. The percent loss of colony forming ability of the cells, a measure of cytotoxicity of the released Dox, was the same as parent Dox solutions, indicating that the drug bioactivity was fully preserved after the drug loading and release cycle. This work demonstrated that various drug release rates were achieved by varying the drug loading and that the MS-delivered Dox was effective against the cancer cells in vitro.

Animals↗

PubMed2001

[Ultrastructural observation and analysis of thin basement membrane nephropathy].

In order to improve the diagnosis of thin basement membrane nephropathy, we observed the ultrastructure of renal biopsy specimens from five cases with thin basement membrane nephropathy, and selectively measured the thickness of the basement membrane. The result showed: 1. The thickness of the basement membrane of five patients was less than 250 nm. 2. The thickness of the basement membrane was positively related to the course of disease (r = 0.65), While negatively related to the grade of haematuria (r = -0.39). The results suggest that hypoplasia may be the cause of extensively thinning of the basement membrane.

Adult↗

PubMed2001

[Changes of ultrastructure and function of the aortic endothelium in streptozotocin-diabetic rats and effect of perindopril].

UNLABELLED: To investigate the alteration of ultrastructure and function of the aortic endothelium in streptozotocin (STZ)-diabetic rats and the effect of perindopril, male SD rats were randomly divided into normal group (NC), diabetes control group (DC), diabetes group treated with perindopril (2 mg.kg-1.d-1) which was administered after 4 weeks. At 4, 8, 16 weeks after injecting STZ, glucose, plasma endothelin-1 and angiotensin II were respectively measured, and we also observed aortic endothelial cell under the electron microscope. RESULTS: In DC group, there were mitochondrial edema and vacuolization obviously in aortic endothelial cells at 8 weeks, and extensive endothelial cell necrosis and exfoliation were observed at 16 weeks, while pathological changes in the DP group were abated significantly. Plasma Ang II levels were increased significantly at different times in DC group, and plasma ET-1 levels were obviously increased at 8 weeks and greatly decreased at 16 weeks. In DP groups, plasma Ang II levels obviously decreased, ET-1 levels declined at 8 weeks and statistically elevated at 16 weeks. CONCLUSION: There are changes of ultrastructure and function in aortic endothelial cell in different durations of diabetes. Plasma ET-1 level may be a marker of aortic endothelial cell injury, perindopril may have protective effect on aortic endothelial cell in diabetic rats.

Angiotensin II↗