Biomedical subjects

Yi-Ping Wang

Publications and source records attributed to Yi-Ping Wang.

26 records · Page 2Linked to original sources

PubMed2004

Tetrahydroacridine inhibits voltage-dependent Na(+) current in guinea-pig ventricular myocytes.

AIM: To study the effects of tetrahydroacridine (tacrine) on voltage-gated Na(+) channels in cardiac tissues. METHODS: Single ventricular myocytes were enzymatically dissociated from adult guinea-pig heart. Voltage-dependent Na(+) current was recorded using whole cell voltage-clamp technique. RESULTS: (1) Tacrine reversibly inhibited Na(+) current with an IC(50) value of 120 micromol/L (95 % confidence range: 108-133 micromol/L). (2) The inhibitory effects of tacrine on Na(+) current exhibited both a tonic nature and use-dependence. (3) Tacrine at 100 micromol/L caused a negative shift (about 10 mV) in the voltage-dependence of steady-state inactivation of Na(+) current, and retarded its recovery from inactivation, but did not affect its activation curve. (4) Intracellular application of tacrine significantly inhibited Na(+) current. CONCLUSION: In addition to blocking other voltage-gated ion channels, tacrine blocked Na(+) channels in guinea-pig ventricular myocytes. Tacrine acted as inactivation stabilizer of Na(+) channels in cardiac tissues.

Animals↗

PubMed2003

Characteristics of calcifying odontogenic cyst in Taiwanese.

BACKGROUND AND PURPOSE: Calcifying odontogenic cyst (COC) is a rare type of odontogenic cyst. This retrospective study analyzed the clinical, radiographic, and histopathologic features of COC in Taiwanese. METHODS: Ten cases of COC in 2 male and 8 female patients with a mean age of 29 years (range, 11 to 48 years) treated from January 1985 to December 2002 were included. Microscopic slides, clinical histories, and radiographic features of these 10 COC cases were reviewed and analyzed. RESULTS: COCs occurred in the maxilla in 3 cases and in the mandible in 7 cases. COCs were associated with impacted teeth in 6 cases and with odontomas in 3 cases. All COCs appeared as either unilocular (9 cases) or multilocular (1 case) radiolucencies. In 7 cases, spotty radiopaque materials were scattered throughout the radiolucency. Histologically, all of the lesions were at least partially lined by epithelium with cuboidal to columnar basal cells and stellate reticulum-like suprabasal cells. Variable numbers of ghost cells, some of which were calcified, were observed in the lining epithelium or in the fibrous connective tissue wall of all 10 cases. Juxta-epithelial dentinoid was also found in all cases. However, proliferation of ameloblastoma-like tumor nests was observed in only 1 case. Based on the above histologic findings, 6 COC lesions were classified as simple unicystic type, 3 as unicystic odontoma-producing type, and 1 as unicystic ameloblastomatous proliferating type. CONCLUSIONS: COC occurs frequently in the second and third decades and is commonly associated with an impacted tooth or an odontoma. It usually appears as a mixed radiolucent and radiopaque lesion radiographically. Simple unicystic type is the most common type of COC. No recurrences were found after conservative surgical removal in this series.

Adolescent↗

PubMed2003

Odontoma: a clinicopathologic study of 81 cases.

BACKGROUND AND PURPOSE: Odontoma is the most common odontogenic tumor. It includes 2 types, the compound and complex odontomas. There has not been a series study of the clinical and histologic features of odontomas from Taiwan. This study evaluated the clinicopathologic features of odontoma in Taiwanese. METHODS: Cases of odontoma treated from 1998 to 2002 identified from medical records were included. The microscopic features, radiographic features, and clinical history of the patients were reviewed and analyzed. RESULTS: A total of 81 odontomas in 81 patients (36 males and 45 females) were included. There were 62 compound and 19 complex odontomas. The mean age of the patients was 18 years with the majority of odontomas occurring in the first (32%) and second decade (38%) of life. Odontomas had a marked predilection for the maxilla (70%) and for the anterior region of the jaw (83%), particularly for the anterior maxilla (62%). Sixty four (79%) of the 81 odontomas were associated with 80 impacted teeth, including 71 permanent teeth, 2 deciduous teeth, and 7 supernumerary teeth. Of the 71 impacted permanent teeth, the maxillary central incisor (27%) was most commonly affected, followed by the maxillary canine (26%) and mandibular canine (24%). Histologic examination revealed enamel matrix in 90%, dentin in 100%, cementum in 88%, pulp tissue in 96%, fibrous capsule in 93%, ghost cells in 83%, reduced enamel epithelium in 86%, and nests of odontogenic epithelium in 58% of odontomas. Dentigerous cyst was associated with 9% of odontomas. CONCLUSIONS: In this series, odontomas occurred most often in the first and second decade of life. Although complex odontomas are usually found in the posterior jaw, in this Taiwanese series they were most commonly found in the anterior maxilla. Odontoma is frequently associated with an impacted tooth and occasionally with a dentigerous cyst. No recurrence of odontomas was found after surgical excision with follow-up of 1 to 15 years.

Adolescent↗

PubMed2002

Superoxide anion impairs contractility in cultured aortic smooth muscle cells.

We examined the effects of superoxide anion (O) generated by xanthine plus xanthine oxidase (X/XO) on the intracellular Ca(2+) concentration ([Ca(2+)](i)) and muscle contractility in cultured bovine aortic smooth muscle cells (BASMC). Cells were grown on collagen-coated dish for the measurement of [Ca(2+)](i). Pretreatment with X/XO inhibited ATP-induced Ca(2+) transient and Ca(2+) release-activated Ca(2+) entry (CRAC) after thapsigargin-induced store depletion, both of which were reversed by superoxide dismutase (SOD). In contrast, Ca(2+) transients induced by high-K(+) solution and Ca(2+) ionophore A-23187 were not affected by X/XO. BASMC-embedded collagen gel lattice, which was pretreated with xanthine alone, showed contraction in response to ATP, thapsigargin, high-K(+) solution, and A-23187. Pretreatment of the gel with X/XO impaired gel contraction not only by ATP and thapsigargin, but also by high-K(+) solution and A-23187. The X/XO-treated gel showed normal contraction; however, when SOD was present during the pretreatment period. These results indicate that O(2)(-) attenuates smooth muscle contraction by impairing CRAC, ATP-induced Ca(2+) transient, and Ca(2+) sensitivity in BASMC.

Adenosine Triphosphate↗

PubMed2002

Effects of the tyrosine protein kinase inhibitor genistein on the proliferation, activation of cultured rat hepatic stellate cells.

AIM: Hepatic stellate cell (HSC) plays a pivotal role in liver fibrosis and is considered as the therapeutic target for the treatment of hepatic fibrosis. Tyrosine protein kinase plays an important role in the proliferation, activation of HSC. The purpose of the study is to investigate the effects of the tyrosine protein kinase inhibitor genistein on the proliferation and activation of cultured rat HSC. METHODS: Rat HSC were isolated from Wistar rats by in situ perfusion of collagenase and pronase and single-step density Nycodenz gradient. Culture-activated HSC were serum-starved and incubated with 10(-9) to 10(-5) mol/L concentration of genistein for 24, 48 or 72 h. In PDGF-induced HSC proliferation, HSC were stimulated with 10 microg.L(-1) PDGF-BB for 15 min, and then treated with genistein for the same time. Cell proliferation was measured by MTT assay and based on flow cytometric analysis of cell cycle. The a-smooth muscle actin (alpha-SMA) expression in HSC was studied with confocal laser microscopy and flow cytometry. c-fos, c-jun and cyclin D(1) expression in HSC was also detected by flow cytometry. RESULTS: Genistein inhibited basal and PDGF-induced proliferation of HSC at the concentration of 10(-8) to 10(-5)mol/L, and treatment with 10(-7) mol/L concentration of genistein for 48 h inhibited the HSC proliferation significantly (the inhibition rate was 70.3 %, P<0.05). Immunofluorescence detected by confocal laser microscopy and flow cytometry showed that treatment with 10(-7) mol/L genistein for 48 h suppressed the expression of alpha-SMA significantly in HSC (the specific fluorescence intensity were 60.2+/-21.5 vs 35.3+/-11.6 and 12.8+/-10.4 vs 9.54+/-6.39, respectively, both P<0.05). The intensity of c-fos, c-jun and cyclin D(1) expression of HSCs treated with 10(-7)mol/L genistein for 48 h was also significantly decreased compared with the controls. CONCLUSION: Genistein influences proliferation of HSC, suppresses the expression of alpha-SMA in HSC and t inhibits the intensity of c-fos, c-jun and cyclin D(1) expression of HSCs. Genistein has therapeutic potential against liver fibrosis.

Actins↗

PubMed2002

Effect of magnesium lithospermate B on calcium and nitric oxide in endothelial cells upon hypoxia/reoxygenation.

AIM: To investigate the effect of magnesium lithospermate B (MLB) on hypoxia/ reoxygenation (H/R)-induced elevation of intracellular calcium concentration ([Ca2+]i) and nitric oxide (NO) release in endothelial cells. METHODS: The cultured human umbilical vein endothelial cells (ECV304) were exposed to hypoxia for 30 min under 95 % N2 and 5 % CO2, then reoxygenation for 30 min under air and 5 % CO2. Cell injury was evaluated by dye exclusion test, superoxide dismutase (SOD) assay, and molondialdehyde (MDA) assay. [Ca2+]i was determined by Fura 2-AM. NO content was examined by a NO assay kit. Endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) mRNA expressions were measured by semi-quantitative RT-PCR. RESULTS: Cell viability was decreased from (93.1+/-1.2) % in normoxia to (88+/-3) % in H/R (P < 0.01), and SOD activity was also decreased from (0.24+/-0.07) kNU/L to (0.18+/-0.03) kNU/L in H/R (P >0.05), but MDA production was increased from (1.12+/-0.06) mmol/L in normoxia to (3.78+/-0.03) mmol/L in H/R (P < 0.01) in ECV304 cultured under calcium conditions. MLB 2.5, 5, and 10 mg/L increased cell viability and SOD activity, and inhibited MDA formation in ECV304. H/R increased [Ca2+]i (F340/F380 from 1.65+/-0.16 to 1.89+/-0.28), NO release [from (7.5+/-1.3) micromol/L to (16+/-5) micromol/L], and eNOS mRNA expression, but decreased iNOS mRNA expression in ECV304 (P <0.05). However, it did not affect them under calcium-free conditions. MLB inhibited H/R-induced increases in [Ca2+]i and eNOS mRNA expression, stimulated NO release and iNOS mRNA expression (P <0.05). CONCLUSION: MLB attenuates H/R-induced cell injury and increases NO release in ECV304. This increase of NO production is possibly associated with preventing cell injury induced by H/R in MLB-treated ECV304.

Calcium↗

PubMed2002

[Studies on production, purification and partial characteristics of the extracellular laccase from Armilliria mellea].

The production conditions of extracellular laccase from Armilliria mellea and the characteristics of the enzyme were studied. The experiment proved that initial pH5.5 of the culture medium and temperature at 25 degrees C were favorable for laccase synthesis. As carbon resources, cellobiose and raffinose were better in terms of productivity than maltose, sorbose and galactose. Organic nitrogen source was more suitable for Armilliria mellea to synthesize laccase than inorganic nitrogen source. Peat extract (PE) enhanced notably the yield of laccase; the maximal yield was 7 times as much as that of the control when PE concentration was 50%. Three isozymes were detected in culture supernatant named A, B and C respectively after their mobility on PAGE. After concentrated by (NH4)2SO4 precipitation, laccase A was further purified to homogeneity by preparative native PAGE and anion exchange column chromatography. The native enzyme was a single polypeptide with a molecular mass of approximately 59 kD estimated by SDS-PAGE, while 58 kD by gel filtration chromatography under non-denaturing conditions. Determined by IEF its isoelectric point was 4.0. The optimal pH value and temperature were 5.6 and 60 degrees C respectively in catalytic reaction of oxidizing guaiacol. At 60 degrees C and 65 degrees C, half-lives of laccase A were 45 min and 36.8 min, respectively. Enzyme activity was inhibited with 100 mmol/L Cl-, but was activated with 1 mmol/L SO4(2-). However, if the concentration of NaN3 was only 1 mmol/L, laccase A lost its activity completely. 10 mmol/L EDTA had no effect on laccase A, while 1 mmol/L Cu2+ could enhance its activity. Laccase A showed a good stability when the pH of the buffer varied from 5.2 to 7.2. Using guaiacol as the substrate, the Km was 1.026 mmol/L and the Vmax was 5 mumol/(min.mg); using ABTS instead, the Km was 0.22 mmol/L and Vmax was 69 mumol/(min.mg).

Agaricales↗

PubMed2002

[Molecular mapping of QTLs for rice milling yield traits].

QTLs of three milling yield traits, including brown rice (BR,%), milled rice (MR,%) and head milled rice (HR,%), were mapped using a set of 212 Lemont/Teqing RI population, an RFLP linkage map with 182 markers and a mixed model approach(QTLMapper V1.0). The population showed continuous distributions with transgressive segregation on both sides for all traits while HR had a wider variation than BR and MR. One and four main effect QTLs were detected for MR and HR. Two QTLs for HR(QHr6 and QHr7) had large additive effects. Twelve, five and sixteen pairs of digenic epistatic loci were associated with BR, MR and HR respectively. Epistasis was more important than main effect QTLs according to the mapping result. A complex relationship was observed for epistatic pairs mapped in same trait or among different traits by sharing intervals.

Chromosome Mapping↗