MATERIALS AND METHODS: A single dose of 30 Gy of linear electron beam radiation was applied to the hind limb of nude mice before creating the skin lesion (area of 78.6 mm). Monolayer tissue-engineered skin substitutes (MTESSs) were prepared by entrapping cultured keratinocytes in fibrin matrix, and bilayer tissue-engineered skin substitutes (BTESSs) were prepared by entrapping keratinocytes and fibroblasts in separate layers. Bilayer tissue-engineered skin substitute and MTESS were implanted to the wound area. Gross appearance and wound area were analyzed to evaluate wound healing efficiency. Skin regeneration and morphological appearance were observed via histological and electron microscopy. Protein expressions of transforming growth factor β1 (TGF-β1), platelet-derived growth factor BB (PDGF-BB), and vascular endothelial growth factor (VEGF) in skin regeneration were evaluated by immunohistochemistry (IHC).
RESULTS: Macroscopic observation revealed that at day 13, treatments with BTESS completely healed the irradiated wound, whereas wound sizes of 1.1 ± 0.05 and 6.8 ± 0.14 mm were measured in the MTESS-treated and untreated control groups, respectively. Hematoxylin-eosin (H&E) analysis showed formation of compact and organized epidermal and dermal layers in the BTESS-treated group, as compared with MTESS-treated and untreated control groups. Ultrastructural analysis indicates maturation of skin in BTESS-treated wound evidenced by formation of intermediate filament bundles in the dermal layer and low intercellular space in the epidermal layer. Expressions of TGF-β1, PDGF-BB, and VEGF were also higher in BTESS-treated wounds, compared with MTESS-treated wounds.
CONCLUSIONS: These results indicate that BTESS is the preferred treatment for irradiated wound ulcers.
OBJECTIVE: The objective of this study was to determine the effects of T3 derivatives, σ-T3, γ-T3 and α-T3 on insulin secretion of rat pancreatic islets in a dynamic culture.
METHOD: Pancreatic islets isolated from male Wistar rats were treated with T3 for 1 h at 37°C in a microfluidic system with continuous operation that provided a stable cell culture environment. Glucose (2.8 mM and 16.7 mM, as basal and stimulant, respectively) and potassium chloride (KCl) (30 mM) were added to the treatment in calcium free medium. The supernatant was collected for insulin measurements.
RESULTS: Short-term exposure (1 h) of σ-T3 to β cells in the stimulant glucose condition significantly potentiated insulin secretion in a dose-dependent manner. γ-T3 and α-T3 also displayed dosedependent effect but were less effective in the activation of insulin secretion. Essentially, KCl, a pancreatic β cell membrane depolarizing agent, added into the treatment further enhanced the insulin secretion of σ-T3, γ-T3 and α-T3 with ED50 values of 504, 511 and 588 µM, respectively.
CONCLUSION: The findings suggest the potential of σ-T3 in regulating glucose-stimulated insulin secretion (GSIS) in response to the intracellular calcium especially in the presence of KCl.
OBJECTIVE: This study investigates the vasorelaxant mechanism of VA ethanol extract (VAE) and analyzes its tri-step FTIR spectroscopy fingerprint.
MATERIALS AND METHODS: Dried VA leaves were extracted with ethanol through maceration and concentrated using rotary evaporator before freeze-dried. The vasorelaxant activity and the underlying mechanisms of VAE using the cumulative concentration (0.01-2.55 mg/mL at 20-min intervals) were evaluated on aortic rings isolated from Sprague Dawley rats in the presence of antagonists.
RESULTS: The tri-step FTIR spectroscopy showed that VAE contains alkaloids, flavonoids, and saponins. VAE caused the relaxation of pre-contracted aortic rings in the presence and absence of endothelium with EC50 of 0.057 ± 0.006 and 0.430 ± 0.196 mg/mL, respectively. In the presence of Nω-nitro-l-arginine methyl ester (EC50 0.971 ± 0.459 mg/mL), methylene blue (EC50 1.203 ± 0.426 mg/mL), indomethacin (EC50 2.128 ± 1.218 mg/mL), atropine (EC50 0.470 ± 0.325 mg/mL), and propranolol (EC50 0.314 ± 0.032 mg/mL), relaxation stimulated by VAE was significantly reduced. VAE acted on potassium channels, with its vasorelaxation effects significantly reduced by tetraethylammonium, 4-aminopyridine, barium chloride, and glibenclamide (EC50 0.548 ± 0.184, 0.158 ± 0.012, 0.847 ± 0.342, and 0.304 ± 0.075 mg/mL, respectively). VAE was also found to be active in reducing Ca2+ released from the sarcoplasmic reticulum and blocking calcium channels.
CONCLUSIONS: The vasorelaxation effect of VAE involves upregulation of NO/cGMP and PGI2 signalling pathways, and modulation of calcium/potassium channels, and muscarinic and β2-adrenergic receptor levels.