Biomedical subjects

Yao-Horng Wang

Publications and source records attributed to Yao-Horng Wang.

8 recordsLinked to original sources

PubMed2007

Injecting partially digested cartilage fragments into a biphasic scaffold to generate osteochondral composites in a nude mice model.

This study proposed a novel scaffold with heterogeneous morphology that mimics the natural tissue. Its upper part contains a hollow cavity surrounded by a wall of poly(L-lactic-co-glycolic acid) (PLGA) porous membrane for injecting cartilage tissue and cells. An interconnecting porous structure located under the hollow cavity was made of composite materials that combined PLGA and beta-tricalcium phosphate (beta-TCP) to simulate the subchondral bone. Adult pig articular cartilage was cut and sieved into small fragments. The tissue fragments was partially digested by 0.1% collagenase for 0, 2, 4, and 6 h and injected into the hollow cavity of the biphasic scaffold. The biphasic scaffolds were then implanted into the subcutaneous pocket of nude mice for 4 weeks. No tissue bonding or new cartilaginous tissue formation was identified in the cartilage fragment without enzymatic treatment. The cartilage fragments digested with 2 h of collagenase digestion were partially integrated after implantation. The integrative properties of the cartilage fragment depended on the extent of enzymatic digestion. Releasing cells at the tissue surface enhanced confluence and bonding of the cartilage fragment matrix. Complete integration of the cartilage fragments and cartilage remodeling were achieved by digestion of the tissue fragments with 4 h of enzymatic treatment. The neocartilage grew from the upper hollow cavity into the lower PLGA/beta-TCP porous structure, forming an interface similar to that formed between cartilage and subchondral bone. This study combined the osteochondral scaffold and limited cartilage tissues to generate cartilage tissue in vivo intending for repairing full-thickness articular cartilage defects.

Animals↗

PubMed2006

Propolis extracts exhibit an immunoregulatory activity in an OVA-sensitized airway inflammatory animal model.

Propolis, which has been used widely in folk medicine, has been shown to exhibit various biological activities but its immunoregulatory and anti-inflammatory activities in intact animals have not been well studied. We investigated these activities of propolis using an ovalbumin-induced asthma animal model. Mice were immunized and sensitized by exposure to ovalbumin (OVA) antigen and administered with low- (65 mg/kg body weight) and high-dose (325 mg/kg body weight) propolis water extracts by tube feeding. The serum OVA-specific IgE titer and cytokine profiles in cultured splenocytes and bronchoalveolar lavage fluids (BALF) were analyzed. The number of eosinophils in BALF was counted. Here we demonstrate that propolis extracts can suppress the serum levels of OVA-specific IgE and IgG(1), and airway hyperresponsiveness (AHR) in OVA-sensitized mice. There are no significant differences in the concentration of eotaxin or the number of eosinophils in BALF among the four groups. However, the higher dose of propolis extracts decreases the level of IL-5 in BALF. The splenocytes from mice administered with propolis extracts (low- and high-dose groups) exhibit a strong inhibition of IL-10 secretion and up-regulation of IFN-gamma secretion in splenocytes stimulated with concanavalin A (ConA). In addition, cytokine (IFN-gamma, IL-6, and IL-10) secretion in OVA-stimulated splenocytes from the propolis groups was significantly lower than that in the control group. These results suggest that propolis extracts may be a potential novel therapeutic agent for asthma.

Animals↗

PubMed2006

The effects of epithelial viability on stromal keratocyte apoptosis in porcine corneas stored in Optisol-GS.

PURPOSE: To investigate the effect of corneal epithelium on the viability of corneal stromal keratocytes in Optisol-GS. METHODS: After sterilization, corneoscleral buttons were excised and stored in Optisol-GS for various time periods. Group 1 corneas (n = 40) underwent mechanical corneal epithelial debridement before storage while group 2 corneas (n = 40) were stored with intact epithelium. Changes in corneal thickness, keratocyte density, and keratocyte apoptosis were investigated immediately, at 4 hours, and on days 1, 2, 3, 5, 7, and 14 in the preservation medium. The differences between group 1 and 2 corneas were analyzed. RESULTS: Corneal thickness increased significantly in the second week of preservation in both groups, though more substantially in group 1. Significant corneal epithelial apoptosis was noticed in the first week in group 2 corneas. Corneal stromal keratocyte density decreased with prolonged preservation time. DNA laddering was detected by ligation-mediated polymerase chain reaction throughout the experiment periods in both groups, but the increase of keratocyte apoptosis was more significant after 5 days of preservation, especially in group 1. CONCLUSIONS: Stromal keratocytes underwent apoptosis in Optisol-GS. The absence of corneal epithelium during preservation further increased the stromal keratocyte apoptosis.

Animals↗

PubMed2006

Ethanol treatment induces significant cell death in porcine corneal fibroblasts.

PURPOSE: To explore the effect of ethanol treatment on corneal stromal cells. METHODS: Primary porcine corneal fibroblasts from passages 3 to 5 were treated with ethanol at concentrations of 10%, 15%, 20%, and 50% for 30 seconds. A control group was treated with phosphate-buffered saline (PBS) for 30 seconds. Morphologic changes were documented with phase-contrast microscopy, and the growth curves were examined with a PicoGreen assay. Cellular viability was examined with an ethidium homodimer and calcein-AM stain, whereas cellular apoptosis and/or necrosis were analyzed by a YO-PRO-1 dye/propidium iodide apoptosis assay coupled with flow cytometry and further confirmed with a genomic DNA pattern assay. Cellular toxicity was examined with a lactate dehydrogenase (LDH) assay. RESULTS: Significant cell rounding and detachment from the culture dish were noticed after 20% ethanol treatment of 30 seconds, despite that the cell morphology remained unchanged in the PBS and 10% and 15% ethanol groups. Twenty percent ethanol induced significant cellular toxicity, causing cell death as shown by ethidium homodimer and calcein-AM stain, YO-PRO-1 dye/propidium iodide apoptosis assay, and LDH assay, although 10% and 15% ethanol caused minimal changes to corneal fibroblasts. Cellular death was most significant 6 hours after the 20% ethanol treatment. The genomic DNA pattern revealed intact DNA in the control, 10% ethanol, and 15% ethanol groups at all times, whereas DNA smearing was noticed at 48 hours after the 20% ethanol treatment. However, none of the DNA examined revealed significant DNA laddering patterns of apoptosis. Fifty percent ethanol treatment of 30 seconds resulted in cell fixation and cell death. CONCLUSION: Treatment with 20% ethanol for 30 seconds induced significant porcine corneal fibroblast cell death, whereas 10% and 15% ethanol treatment of 30 seconds caused minimal changes. We propose that, when applied for 30 seconds, 20% ethanol is the threshold level that causes cell death in cultured porcine corneal fibroblasts.

Animals↗

PubMed2004

Lethal quercetin-digoxin interaction in pigs.

Digoxin is a popular cardiac glycoside with very narrow therapeutic range. Quercetin is an ubiquitous antioxidant flavonoid. Digoxin is a substrate of P-glycoprotein (P-gp), a multi-drug efflux transporter, and quercetin was reported to be a modulator of P-gp. The aim of this study was to investigate the effect of quercetin on the absorption and disposition of digoxin in pigs. Pigs were orally given digoxin (0.02 mg/kg) with and without quercetin in crossover designs. The blood was collected via jugular vein and fluorescence polarization immunoassay was used to determine the serum concentration of digoxin. The pharmacokinetic parameters were calculated using WINNONLIN. The paired Student's t-test was used for statistical comparison. The coadministration of 50 mg/kg quercetin unexpectedly resulted in sudden death of two among three pigs within 30 min after digoxin administration. The coadministration of 40 mg/kg quercetin significantly elevated the Cmax of digoxin by 413% and increased the AUC0-t by 170%. The results indicated that a very serious pharmacokinetic interaction occurred between quercetin and digoxin. The concomitant administration of digoxin and quercetin or quercetin-containing herbs and dietary supplement should be avoided.

Animals↗

PubMed2002

Quercetin significantly decreased cyclosporin oral bioavailability in pigs and rats.

Cyclosporin, an immunosuppressant with a narrow therapeutic window, is a substrate for both CYP3A4 and P-glycoprotein (Pgp). Quercetin is an inhibitor of CYP3A4 and a modulator of Pgp. This study aimed to measure the effect of quercetin on the absorption and disposition of cyclosporin in pigs and rats. Cyclosporin (Sandimmune, 10 mg/kg) was orally administered with and without a concomitant dose of quercetin (50 mg/kg) to pigs and rats. Cyclosporin concentrations in blood samples were determined by a specific monoclonal fluorescence polarization immunoassay. The pharmacokinetic parameters were calculated by noncompartmental analysis using WINNONLIN. A paired Student's t-test was conducted for statistical comparison. A study using the everted intestinal sac was carried out to evaluate the effect of quercetin on the function of intestinal Pgp. The coadministration of quercetin significantly decreased cyclosporin AUC(0-3) (area under the concentration-time curve from time zero to 3 h) by 56% and AUC(0-t) (area under the concentration-time curve from time zero to the last point) by 43% in pigs and rats, respectively, indicating that the coadministration of quercetin significantly decreased cyclosporin oral bioavailability. However, the inverted sac study showed that quercetin significantly inhibited the function of intestinal Pgp. It is suggested that concurrent use of quercetin or quercetin-containing dietary supplement or herbs with cyclosporin or other medications whose absorption and metabolism are mediated by Pgp and/or CYP3A4 should require close monitoring.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2002

Synthetic TGF-beta antagonist accelerates wound healing and reduces scarring.

Wound healing consists of re-epithelialization, contraction and formation of granulation and scar tissue. TGF-b is involved in these events, but its exact roles are not well understood. Here we demonstrate that topical application of a synthetic TGF-b antagonist accelerates re-epithelialization in pig burn wounds (100% re-epithelialization in antagonist-treated wounds vs. approximately 70% re-epithelialization in control wounds on postburn day 26) and reduces wound contraction and scarring in standard pig skin burn, pig skin excision and rabbit skin excision wounds. These results support the distinct roles of TGF-b in the complex process of wound healing and demonstrate the feasibility of manipulating wound healing by TGF-b antagonist.

Animals↗

PubMedDate not supplied

Effect of Surgecel coverage with topical electrocauterization for preventing and sealing pulmonary air leakage.

Pleural tears usually occur after pneumolysis for dense adhesion or after cone biopsy of lung parenchyma. Repair of the tears is sometimes very difficult. Herein we compared different methods on a pig lung air leak model. Twenty pigs with pleural tears by surgical manipulation through sternotomy were not treated (n = 5) or treated by simple electroablation (n = 5), pleural coverage (n = 5), or Surgecel coverage with surface electroablation (n = 5). We evaluated their immediate and delayed treatment effect by measuring the critical leak pressure, degree of air leakage, and air leakage period and histological examination. It was found that Surgecel coverage with surface electrocauterization had similar early and delayed effects in sealing air leakage to pleural coverage and was much better than the other two groups (P < 0.05). We conclude that coverage with Surgicel with local electroablation can significantly decrease immediate and late air leakage from pleural tears.

Analysis of Variance↗