METHODS: The Bovine Corneal Opacity and Permeability test method (BCOP), OECD Test Guideline 437, was used as an initial step to study the inducing effect of palm-based MES on irreversible eye damage. The second assessment involved the use of reconstructed human corneal-like epithelium test method, OECD Test Guideline 492 using SkinEthic™ Human Corneal Epithelium to study the potential effect of palm-based MES on eye irritancy. The palm-based MES were prepared in 10% solution (w/v) in deionized water and tested as a liquid and surfactant test substances whereby both test conducted according to the liquid/surfactant treatment protocol.
RESULTS: The preliminary BCOP results showed that palm-based MES; C12, C14, C16, C16:18 were not classified as severe eye irritants test substances with in vitro irritancy score between 3 and the threshold level of 55. The second evaluation using SkinEthic™ HCE model showed that palm-based MES; C12, C14, C16, C16:18 and three commercial samples were potentially irritants to the eyes with mean tissue viability ≤ 60% and classified as Category 2 according to United Nations Globally Harmonized System of Classification and Labelling of Chemicals. However, there are some limitations of the proposed ocular irritation classification of palm-based MES due to insolubility of long chain MES in 10% solution (w/v) in deionized water.
CONCLUSION: Therefore, future studies to clarify the eye irritation potential of the palm-based MES will be needed, and could include; methods to improve the test substance solubility, use of test protocol for solids, and/or inclusion of a benchmark anionic surfactant, such as sodium dodecyl sulphate within the study design.
METHODS: 15wt% of zirconia (ZrO2) as well as 30, 35, and 40wt% of beta-tricalcium phosphate (β-TCP) were compounded with PA 12, followed by the fabrication of filament feedstocks using a single screw extruder. The fabricated filament feedstocks were used to print the impact specimens. The melt flow rate, tensile properties of fabricated filament feedstocks, and 3D printed impact properties of the specimens were assessed using melt flow indexer, universal testing machine, and Izod pendulum tester, respectively. The microstructure of selected filament feedstocks and broken impact specimens were analysed using a field emission scanning electron microscope and universal testing machine. Human periodontal ligament fibroblast cells (HPdLF) were used to evaluate the cytotoxicity of the materials by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid) (MTT) assay.
RESULTS: Hybrid ceramics filled PA 12 indicated sufficient flowability for FDM 3D printing. The tensile strength of hybrid ceramics filled PA 12 filament feedstocks slightly reduced as compared to unfilled PA 12. However, the tensile modulus and impact strength of hybrid ceramics filled PA 12 increased by 8%-31% and 98%-181%, respectively. A significant increase was also detected in the cell viability of the developed composites at concentrations of 12.5, 25, 50 and 100mg/ml.
SIGNIFICANCE: The newly developed hybrid ceramics filled PA 12 filament feedstock with improved properties is suitable for an FDM-based 3D printer, which enables the creation of patient-specific craniofacial implant at a lower cost to serve low-income patients.
OBJECTIVES: To develop a novel in vitro skin glycation model as a screening tool for topical formulations with antiglycation properties and to further characterize, at the molecular level, the glycation stress-driven skin ageing mechanism.
METHODS: The glycation model was developed using human reconstituted full-thickness skin; the presence of N(ε) -(carboxymethyl) lysine (CML) was used as evidence of the degree of glycation. Topical application of emulsion containing a well-known antiglycation compound (aminoguanidine) was used to verify the sensitivity and robustness of the model. Cytokine immunoassay, quantitative real-time polymerase chain reaction and histological analysis were further implemented to characterize the molecular mechanisms of skin ageing in the skin glycation model.
RESULTS: Transcriptomic and cytokine profiling analyses in the skin glycation model demonstrated multiple biological changes, including extracellular matrix catabolism, skin barrier function impairment, oxidative stress and subsequently the inflammatory response. Darkness and yellowness of skin tone observed in the in vitro skin glycation model correlated well with the degree of glycation stress.
CONCLUSIONS: The newly developed skin glycation model in this study has provided a new technological dimension in screening antiglycation properties of topical pharmaceutical or cosmeceutical formulations. This study concomitantly provides insights into skin ageing mechanisms driven by glycation stress, which could be useful in formulating skin antiageing therapy in future studies.
MATERIALS AND METHODS: Tincture of the roots was concentrated to dryness by evaporating the ethanol in vacuo. This ethanolic extract was partitioned into 5 fractions sequentially with hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The corpus cavernosum relaxant activity of each fraction was investigated. The DCM fraction which showed the highest potency in relaxing phenylephrine-precontracted corpora cavernosa was purified by column chromatography. The effects of the most potent DCM subfraction in relaxing phenylephrine-precontracted corpora cavernosa, DCM-I, on angiotensin I- or angiotensin II-induced contractions in corpora cavernosa were investigated. The effects of DCM-I pretreatment on the responses of phenylephrine-precontracted corpora cavernosa to angiotensin II or bradykinin were also studied. An in vitro assay was conducted to evaluate the effect of DCM-I on angiotensin-converting enzyme activity.
RESULTS: Fraction DCM-I decreased the maximal contractions (100%) evoked by angiotensin I and angiotensin II to 30 ± 14% and 26 ± 16% (p < 0.001), respectively. In phenylephrine-precontracted corpora cavernosa, DCM-I pretreatment caused angiotensin II to induce 82 ± 27% relaxation of maximal contraction (p < 0.01) and enhanced (p < 0.001) bradykinin-induced relaxations from 47 ± 8% to 100 ± 5%. In vitro, DCM-I was able to reduce (p < 0.001) the maximal angiotensin-converting enzyme activity to 78 ± 0.24%.
CONCLUSION: Fraction DCM-I was able to antagonize angiotensin II-induced contraction to cause corpus cavernosum relaxation via inhibition of angiotensin II type 1 receptor and enhance bradykinin-induced relaxation through inhibition of angiotensin-converting enzyme.
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.
METHODS: Thirty-six mandibular premolar teeth with an average surface area of 64.49 mm2 were prepared to receive CAM/CAM fabricated endocrowns. Samples were divided randomly and equally into groups of lithium disilicate with 2 mm intracoronal depth (LD2), lithium disilicate with 4 mm intracoronal depth (LD4), polymer infiltrated ceramic network with 2 mm intracoronal depth (PICN2) and polymer infiltrated ceramic network with 4 mm intracoronal depth (PICN4). All endocrowns were cemented using ParaCore resin cement with 14N pressure and cured for 20 seconds. Fifty measurements of absolute marginal discrepancy (AMD) were done using a stereomicroscope after cementation. After 24 hours, all samples were subjected to thermocycling before the retention test. This involved using a universal testing machine with a crosshead speed of 0.5 mm/min and applying a load of 500N. The maximum force to detach the crown was recorded in newtons and the mode of failure was identified.
RESULTS: Two-way ANOVA revealed that the AMD for PICN was statistically significantly better than lithium disilicate (p=0.01). No statistically significant difference was detected in the AMD between the two intracoronal depths (p=0.72). PICN and endocrowns with 4 mm intracoronal depth had statistically significant better retention (p<0.05). 72.22% of the sample suffered from cohesive failures and 10 LD endocrowns suffered adhesive failures.
CONCLUSIONS: Within the limitations of this study, we found that different materials and intracoronal depths can indeed influence the retention of CAD/CAM fabricated endocrowns. Based on the controlled setting findings, PICN was found to have better retention and better marginal adaptation than similar lithium disilicate premolar endocrowns.