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Biomedical subjects

Wei Sun

Publications and source records attributed to Wei Sun.

180 records · Page 10Linked to original sources
PubMed2002

Chronic and acute effects of dronedarone on the action potential of rabbit atrial muscle preparations: comparison with amiodarone.

Dronedarone, a noniodinated derivative of amiodarone, is under evaluation as a potentially less toxic anti-arrhythmic alternative to amiodarone. The acute and chronic electrophysiologic effects of dronedarone and amiodarone were compared in isolated rabbit atrial muscle by microelectrode techniques. Four-week PO treatment with dronedarone or amiodarone increased action potential duration (APD90) (58 +/- 4 ms control versus 69 +/- 2 ms dronedarone, p < 0.01; 68 +/- 3 ms amiodarone, p < 0.01 for a 100-mg/kg/d dose) and effective refractory period (49 +/- 6 ms control versus 68 +/- 4 ms dronedarone, p < 0.01; 63 +/- 3 ms amiodarone, p < 0.01). The APD90 prolonged reverse rate-dependency. In contrast, acute superfusion with 10 microM dronedarone or amiodarone decreased APD90 (61 +/- 6 ms control versus 53 +/- 4 ms dronedarone, p < 0.05; 52 +/- 6 ms amiodarone, p < 0.05), effective refractory period (50 +/- 5 ms control versus 44 +/- 4 ms dronedarone, p < 0.05; 43 +/- 6 ms amiodarone, p < 0.05), and the maximum upstroke slope of the action potential (Vmax) (188 +/- 9 V/s control versus 182 +/- 11 V/s dronedarone p < 0.05; 182 +/- 11 V/s amiodarone, p < 0.05). Thus, chronic and acute electrophysiologic effects of dronedarone on rabbit atrial muscle are similar to those of amiodarone, suggesting a similar potential against atrial arrhythmias.

Action Potentials↗
PubMed2002

p53 protein and Ki-67 overexpression in urothelial dysplasia of bladder.

Mutated tumor suppression gene p53 is a common genetic abnormality in most papillary or invasive transitional cell carcinomas (TCC). In these cases, overexpression of p53 protein is detectable in nuclei by immunohistochemical methods. Nuclear antigen Ki-67, a marker of cellular proliferation, has been shown to correlate with the growth of many human neoplasms, including TCC. Since overexpression of p53 protein and increased Ki-67 proliferative activity have been a consistent finding in TCC, p53 and Ki-67 expression may be used as markers of urothelial cells with significant genetic alterations. In this study, the authors have investigated whether there is increased p53 and Ki-67 expression in varying grades of urothelial dysplasia. Staining for p53 and Ki-67 using formalin-fixed, paraffin-embedded sections was performed using a Dako Autostainer, followed by counting positive cells using an automatic cellular imaging system (ACIS). The high-grade dysplasia/CIS group (n = 16) had a similar high percentage and intensity of p53 staining (45.3 +/- 4.3%; 28.2 +/- 6.1 arbitrary units [AU]) as the TCC group (n = 16. 53.6 +/- 3.9%; 36.8 +/- 5.7 AU), but revealed a significantly higher percentage and intensity of p53 staining than the low-grade dysplasia (n = 14, 25.6 +/- 3.3%; 12.2 +/- 2.0 AU) and benign group (n = 10, 10.0 +/- 3.3%; 5.8 +/- 1.7 AU). Percentage of p53-positive cells counted by ACIS was similar to that obtained by manual counting. In addition, expression of Ki-67 in all four groups paralleled p53 expression. The authors' data showing overexpression of p53 and Ki-67 in high-grade urothelial dysplasia/CIS similar to that observed in TCC support the notion that high-grade urothelial dysplasia/CIS is a precursor of invasive TCC.

Carcinoma in Situ↗
PubMed2002

Simultaneous differentiation and typing of Entamoeba histolytica and Entamoeba dispar.

Sequences corresponding to some of the polymorphic loci previously reported from Entamoeba histolytica have been detected in Entamoeba dispar. Comparison of nucleotide sequences of two loci between E. dispar strain SAW760 and E. histolytica strain HM-1:IMSS revealed significant differences in both repeat and flanking regions. The tandem repeat units varied not only in sequence but also in number and arrangement between the two species at both the loci. Using the sequences obtained, primer pairs aimed at amplifying species-specific products were designed and tested on a variety of E. histolytica and E. dispar samples. Amplification results were in complete agreement with the original species classification in all cases, and the PCR products displayed discernible size and pattern variations among the isolates.

Animals↗
PubMed2002

The caudal pressor area of the rat: its precise location and projections to the ventrolateral medulla.

Investigators have demonstrated pressor areas in the medullas of various species. The present study precisely localized the pressor area in the caudal medulla of the rat and determined its projections to the caudal and rostral ventrolateral medulla. The caudal medulla first was mapped grossly in rats with injections (30 nl) of glutamate (30-, 15-, and 7.5-nmol doses) placed 0.5, 1.0, and 1.5 mm caudal to the calamus scriptorius, 1.0, 1.5, and 2.0 mm lateral to the midline, and 1.8, 1.7, and 1.6 mm ventral to the dorsal medullary surface, respectively, and their arterial pressures were recorded. One of these nine injections showed significant increases in arterial pressure. We micromapped this area with a total of 27 injections of glutamate (10 nl; 5 nmol) placed 300 microm apart at 3 different dorsoventral levels. This micromapping study pinpointed the precise location of caudal pressor area (CPA) neurons in a restricted region lateral to the caudal end of the lateral reticular nucleus and ventromedial to the medullary dorsal horn near the level of the pyramidal decussation. Injections of glutamate into this spot, 1.0 mm caudal to the calamus scriptorius, 2.0 mm lateral to the midline, and 1.7 mm ventral from the dorsal surface of the medulla, induced significant increases in arterial pressure. The neuroanatomic connections of neurons in the CPA to the ventrolateral medulla were then investigated with iontophoretic injections of either the anterograde tracer biotinylated dextran amine (BDA) made into the CPA or the retrograde tracer FluoroGold (FG) injected into either the caudal or rostral ventrolateral medulla. BDA injections resulted in bouton-laden fibers throughout both caudal and rostral portions of the ventrolateral medulla. Either of the FG injections resulted in numerous spindle-shaped neurons interspersed between the longitudinal fiber bundles running through the CPA area. The proximity of the CPA neurons to the A1 catecholaminergic cell group is discussed.

Animals↗
PubMed2002

Azimilide inhibits multiple cardiac potassium currents in human atrial myocytes.

BACKGROUND: Studies in animal cell preparations suggest that azimilide may produce a more desirable rate-dependent profile of class III action as a result of its effects on both the slowly (I(Ks)) and rapidly (I(Kr)) activating components of potassium current (I(K)). However, relatively little is known about the effects of azimilide on K(+) currents in human atrial cells. The present study investigated the effect of azimilide on the inward rectifier potassium current (I(K1)), delayed rectifier potassium current (I(K)), ultrarapid delayed rectifier current (I(Kur)), and transient outward potassium current (I(to)) in isolated single human atrial myocytes. METHODS: The tight-seal, whole-cell voltage clamp technique was used to investigate the acute effects of azimilide on K(+) currents in single human atrial myocytes. The cells were isolated enzymatically from atrial tissues that were obtained from patients undergoing open-heart surgeries, with the approval of the local Institutional Review Board. RESULTS: The average cell capacitance of the human atrial myocytes was 77.5 +/- 2.8 pF (Mean +/- standard error of mean, total 28 cells from 17 patients). We found that 100 microM of azimilide in the extracellular solution significantly inhibited the inward rectifier potassium current (12.3 +/- 3.1 vs 6.7 +/- 2.0 pA/pF, n = 12, P < 0.05) at the testing potential of -100 mV. Superfusion with 100 microM of azimilide for 10 minutes inhibited I(K) by 51.7 +/- 5.1% (from 3.4 +/- 0.5 to 1.6 +/- 0.2 pA/pF, n = 9, P < 0.01) at the clamping membrane potential of +40 mV. Human atrial cell I(Kur) was inhibited with 100 microM of azimilide by 38.6 +/- 4.4% (from 3.9 +/- 0.5 to 2.3 +/- 0.2 pA/pF, n = 9, P < 0.01, test potential = 40 mV). We also found that the average peak current amplitude of I(to) in these cells was significantly inhibited with 100 microM of azimilide by 60.3 +/- 5.9% (from 10.3 +/- 1.5 to 3.6 +/- 0.3 pA/pF, n = 6, P < 0.01, test potential = 50 mV). CONCLUSION: The present study provides direct evidence that azimilide inhibits multiple cellular transmembrane K(+) currents in freshly isolated human atrial myocytes. Inhibition of these K(+) currents by azimilide, especially of I(Ks) and I(Kur) is likely to be the electrophysiologic basis for the prolongation of the action potential duration in the human atria which mediates its known antifibrillatory effects in atrial fibrillation and flutter.

Analysis of Variance↗
PubMed2002

Pancreatic microcirculatory impairment in experimental acute pancreatitis in rats.

AIM: To study the feature of pancreatic microcirculatory impairment, especially the initial changes, in caerulein-induced experimental acute pancreatitis (AP). METHODS: The pancreatic microcirculation of caerulein-induced AP model was studied by intravital fluorescence microscopy with FITC-labeled erythrocytes (FITC-RBC), scanning electron microscopy of vascular corrosion casts, and light microscopy of Chinese ink-injected/cleared tissues. RESULTS: Animals in caerulein-treated group showed hyperamylemia (X2), pancreatic oedema, infiltration of inflammatory cells in pancreas. Constrictions of intralobular arteriolar sphincters, presence of vacuoles in all layers of sphincter, and gross irregularity in capillary network of acini were found in the AP specimens. The decrease of pancreatic capillary blood flow (0.34+/-0.10 nl x min(-1) vs 0.91+/-0.06 nl x min(-1) of control, P<0.001), reduction of functional capillary density(277+/-13 cm(-1) vs 349+/-8 cm(-1) of control, P<0.001), and irregular intermittent perfusion were observed in caerulein-induced groups. CONCLUSION: Impairment and constriction of pancreatic intralobular arteriolar sphincter are the initial microcirculatory lesions in the early phase of acute pancreatitis, and play a key role in the pancreatic ischaemia and pancreatic microvascular failure in acute pancreatitis.

Acute Disease↗
PubMed2002

[Investigation on development potential of blastomeres isolated from 4-cell human embryos].

OBJECTIVE: To investigate the development potential of blastomeres isolated from 4-cell human embryos. METHODS: Human oocytes were collected after controlled ovarian hyperstimulation and fertilized in vitro. The zona pellucida of 4-cell stage embryos were removed and the embryos were separated to single blastomeres and cultured in vitro. The development and differentiation of the blastomeres were observed. RESULTS: 83 blastomeres were isolated from 20 4-cell and 2 3-cell human embryos. Of those, 35 developed to expanded blastocyst. CONCLUSION: Blastomeres isolated from the 4-cell human embryos have the competence to develop to expanded blastocyst.

Blastocyst↗
PubMed2002

[Analysis on competition and coexistence patterns of Aneurolepidium chinense and its main companion species].

In this study, transects were set in areas where Aneurolepidium chinense and its companion species grew together. Competition and coexistence patterns of these species in the ecotone were analyzed using the following measures:frequency distribution, spatial pattern, and pattern intensity. Patterns of A. chinense and its main companion species were diverse. Aggregation was the tactics for A. chinense to defend the foreign species' invading or disperse itself. There existed competition and coexistence between A. chinense and its main companion species. A. chinense and Phragmite communis competed and coexisted through suppression. A. chinense and Kalimeris interifolia coexisted through competition. Hierochloe glabra and Puccinellia tenuiflora competed with A. chinense through clonal growth. Calamagrostis epigeios was suppressed by A. chinense.

China↗
PubMed2002

[Malignant tumor and hyperfibrinogenemia].

OBJECTIVE: To investigate the blood fibrinogen (FIB) content before and after chemotherapy or radiotherapy in 43 malignant tumor patients. METHODS: COULTER ACL-200 automated coagulation analyzer was used in monitoring FIB in the patients. RESULTS: The FIB content was significantly higher in malignant tumor patients than that in benign disease patients. Significant reduction was observed after treatment which became elevated again when there was recurrence or metastasis. CONCLUSION: Assessment of FIB not only helps to diagnose cancers but evaluate the therapeutic effect and prognosis also.

Biomarkers, Tumor↗
PubMed2002

[Comparison of leaf tissue turnover for Leymus chinensis and Phragmites communis after grazing].

Leaf tissue turnover of Leymus chinensis and Phragmites communis after grazing was studied by application of theory and method of tissue turnover in this paper. The results showed that the number of living leaf of P. communis was larger than that of L. chinensis, but the length of living leaf of L. chinensis was larger than that of P. communis during the whole growth period. Both of the leaf appearance rate and the leaf elongation rate of L. chinensis and P. communis were largest at first, and then they decreased gradually. The rate of leaf wither and leaf senescence were in the converse trend. The leaf lifespan of P. communis was shorter than that of L. chinensis. The velocity of leaf tissue turnover of P. communis was faster than that of L. chinensis. There would be a great loss if the leaf tissue of L. chinensis were not used in time. The quality of grasslands could be improved by different utilization ways and periods.

Animals↗
PubMed2002

[A comparative study on photosynthesis and transpiration of Kelimeris integrifolia in summer and autumn on Songnen grasslands of China].

The diurnal changes in photosynthesis and transpiration of Kelimeris integrifolia in Summer and Autumn on Songnen grasslands were characterized as a two-peak curve, but with some differences between two seasons. It was shown that environmental conditions and plant internal factors had a strong effects on plant photosynthesis and transpiration. The net photosynthetic and transpiration rates of the leaves were positively correlated to photosynthetically active radiation (P < 0.01), and negatively correlated to stomatal resistance as well as intercellular CO2 concentration (P < 0.05). The transpiration rate was positively correlated to leaf temperature and water saturation deficit of the air. Among the above factors, photosynthesis active radiation was the dominant factor, and stomatal resistance also played an important role in plant photosynthesis and transpiration.

China↗
PubMed2001

Gene Expression Changes in Chinchilla Cochlea from Noise-Induced Temporary Threshold Shift.

Acoustic overstimulation produces many anatomical, biochemical and physiological changes in the inner ear. However, the changes in gene expression that underlie these biological changes are poorly understood. Our approach to investigating this problem is to use gene microarrays to measure the changes in gene expression in the chinchilla inner ear following a 3 h or 6 h noise exposure (95 dB SPL, 707-1414 Hz). This noise exposure causes a temporary threshold shift (~40 dB) and a temporary reduction in distortion product otoacoustic emissions (DPOAE), but no permanent hearing loss or hair cell loss. Here, we present data showing (1) the suitability of mouse and human complementary DNA (cDNA) clones for detecting chinchilla cochlear gene transcripts, and (2) the change in cochlear gene transcripts in noise exposed chinchillas. Chinchilla cochlear transcript probes exhibited strong and discrete signals on both mouse and human cDNA filter arrays. Since the strongest hybridization occurred with mouse clones, mouse cDNA microarrays were used to study noise-induced changes in gene expression. Chinchilla cDNA probes were differentially labelled with Cy3 (control) or Cy5 (noise exposed) by random primed synthesis, hybridized to 8750 mouse cDNAs arrayed on microscope slides and analysed by laser fluorescent microscopy. Several classes of genes exhibited time-dependent up regulation of transcription, including those involved in protein synthesis, metabolism, cytoskeletal proteins, and calcium binding proteins. The results are discussed in relationship to previous studies showing noise-induced changes in structural proteins, calcium binding proteins, metabolic enzymes and membrane bound vesicles.

Journal Article↗
PubMedDate not supplied

Linear sweep voltammetric studies on the interaction of brilliant cresyl blue with nucleic acids and its analytical application.

In this paper, the interaction of brilliant cresyl blue (BCB) with nucleic acids was studied and further applied for the microdetermination of nucleic acids. In aqueous Britton-Robinson (B-R) buffer solution, BCB can be easily reduced on the hanging mercury drop electrode (HMDE) and had a sensitive voltammetric reduction peak at -0.09 V (vs. SCE). The reduction peak current of BCB could be greatly decreased by the addition of DNA. The results of voltammetric measurements had indicated that a binding reaction was occurred between BCB and DNA and a new supramolecular complex was formed, which resulted in the decrease of the diffusion coefficient of the reaction solution and the decrease of the reduction peak current correspondingly. The conditions of interaction and the electrochemical detection were carefully investigated. Under the selected conditions, the calibration curves for the detection of fish sperm (fs)DNA, calf thymus (ct)DNA and yeast (y)RNA were established. The linear range of this assay was 1.0-30.0 microg/mL for fsDNA, 1.0-45.0 microg/mL for ctDNA and 1.0-25.0 microg/mL for yRNA, respectively. The detection limits were 0.38 microg/mL fsDNA, 0.43 microg/mL ctDNA, 0.64 microg/mL yRNA. The interaction parameters such as the equilibrium constant and the binding number were calculated by electrochemical method. The results showed that the 2:3 type of complex was formed in the fsDNA-BCB complex with the binding constant as 2.51 x 10(7). The proposed method was further applied to the synthetic samples determination with satisfactory results.

Animals↗
PubMedDate not supplied

Circadian rhythms of heart rate and locomotion after treatment with low-dose acetylcholinesterase inhibitors.

This study tested the hypothesis that repeated exposure to low levels of sarin, pyridostigmine bromide (PB) or their combination, at doses equivalent to those possibly experienced by veterans of the 1991 Persian Gulf War, could lead to persistent or delayed autonomic effects and thus help to explain the cause of clinical findings in this population. Male Sprague-Dawley rats were treated for 3 weeks with: saline injection (0.5 ml kg(-1), s.c., 3 times weekly) with tap drinking water (control); saline injection with PB (80 mg l(-1) in drinking water); sarin injection (62.5 microg kg(-1), s.c., 0.5 x LD(50), 3 times weekly) with tap drinking water (sarin); or sarin injection with PB in drinking water (sarin + PB). At 2, 4 or 16 weeks post-treatment, heart rate (HR) and locomotor activity (LA) were studied by radiotelemetry. Two weeks posttreatment, HR in drug-treated animals was significantly lower than in controls. A decrease in low-frequency HR power spectrum (PS) was found at 00:00 h and 08:00 h with sarin + PB and at 00:00 h with sarin, while total power was enhanced with sarin + PB at 22:00 h. Minimal effects of drug treatments on HR and HR PS were detected at 4 and 16 weeks post-treatment. No significant differences in LA between control and other groups were found. Since no consistent long-term effects were found in any of the variables studied, these experiments do not support the hypothesis that repeated administration of low doses of PB and the nerve agent sarin can induce persistent or delayed alterations in autonomic function.

Animals↗
PubMedDate not supplied

Fine needle aspiration cytology of a low grade myxoid renal epithelial neoplasm: a case report.

BACKGROUND: Recently, several case reports have described a rare but distinct subtype of renal tumor, referred to as a "low grade renal epithelial neoplasm," that appears to have a better prognosis than conventional renal cell carcinoma does. This report describes the cytologic features of this tumor as determined by fine needle aspiration (FNA) biopsy. CASE: A 53-year-old woman with a history of lymphoma had a renal mass incidentally discovered on an abdominal computed tomographic scan performed for lymphoma restaging. Results of an FNA biopsy showed relatively uniform, medium-sized tumor cells with moderate amounts of finely vacuolated or wispy cytoplasm and indistinct cell borders. The nuclei were primarily round with coarse chromatin and had prominent nucleoli. In the cell block preparation, the tumor cells showed a tubular architecture and an abundant myxoid matrix. The patient underwent a partial nephrectomy. The tumor was classified as a low grade myxoid renal epithelial tumor. CONCLUSION: This unusual kidney tumor appears to have distinctive cytomorphologic features, including a uniform population of epithelial cells with round nuclei, an abundant myxoid matrix and tubular architecture.

Biopsy, Fine-Needle↗
PubMedDate not supplied

Grading follicular lymphoma on fine needle aspiration specimens. Comparison with proliferative index by DNA image analysis and Ki-67 labeling index.

OBJECTIVE: To determine whether follicular lymphoma (FL) can be graded on fine needle aspiration (FNA) biopsies by determining the percentage of centroblasts in the neoplastic follicles on the smears. STUDY DESIGN: Eighty-nine cases of histologically confirmed cases of FL, including 31 grade 1, 46 grade 2 and 12 grade 3, were evaluated. Proliferative index (PI) by DNA image analysis (DIA) and Ki-67 labeling index (LI) were obtained on all cases. A minimum of 200 cells were counted per case (range, 200-800 cells) at 40x magnification, and the number of large cells (centroblasts) was expressed as a percentage of the total number of cells counted within the follicles. RESULTS: The percentage of centroblasts in the follicular aggregates was 9.7 +/- 2.9% in grade 1 FLs, 24.7 +/- 5.6% in grade 2 and 48.4 +/- 7.5% in grade 3. These differences were significant (P < .05). DNA image analysis of PI and Ki-67 LI differed significantly between grade 1 FLs and grade 2 and 3 FLs (P < .05), but there were no significant differences between grade 2 and 3 FLs. CONCLUSION: Determining the percentage of centroblasts in the follicular aggregates on FNA specimens is a good method of grading FLs. Using the percentage of centroblasts per follicular structure, FL grades 1, 2 and 3 were adequately distinguished. PI by DIA and Ki-67 LI clearly distinguished FL grade 1 from FL grades 2 and 3; however, it did not clearly distinguish between grades 2 and 3.

Adult↗
PubMedDate not supplied

Pathology case of the month. Abdominal pain and weight loss in a young adult. Anaplastic large cell lymphoma.

A 34-year-old black man presented with a three-month history of abdominal pain, anorexia, and weight loss. Physical examination and radiologic studies revealed diffuse lymphadenopathy. Ascites and bilateral pleural effusions were also evident. The patient's condition deteriorated after admission, and he died prior to initiation of therapy. Histologic sections and special studies performed on a cervical lymph node biopsy performed shortly before the patient's death are shown in Figures 1-4. A bone marrow aspirate and biopsy were also performed and revealed no evidence of disease.

Abdominal Pain↗