Factors affecting adhesion of polymers during coinjection

The co-injection moulding process was studied. The experimental work from several tools, such a square plaque plate moulding has led to an understanding of the mechanism of dual injection mould filling. Emphasis has been focussed the relationships between the rheological property of the polymers and the relevant moulding parameters. The skin-core formations, which cot-relate to these relationships, were also studied. Many factors were introduced for understanding the effect on the skin-core adhesion where the two polymers are incompatible. In this case a compatibiliser was found to be one of the most important factors. In the presence of compatibiliser, the chemical reaction between active functional groups of skill and compatibiliser in the core occurred. Suitable conditions were necessary to produce good bonding between skin and core. The greater thickness of skin layer and greater . simultaneous injection times led to more probability for the skin and core active functional groups to react with each other before the skin became no-flow layer. Methods available to achieve these thicknesses and simultaneous injection times were possible by controlling the moulding parameters, such as melt temperature, tool temperature, injection speeds, and lengths of simultaneous phase-, these parameters could affect the skin-core thickness formations and their adhesion to different degrees

Curcumin improves prostanoid ratio in diabetic mesenteric arteries associated with cyclooxygenase-2 and NF-κB suppression

Sirada Rungseesantivanon1, Naris Thengchaisri4, Preecha Ruangvejvorachai2, Suthiluk Patumraj31Interdepartment of Physiology, Graduate School, 2Department of Pathology, 3Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; 4Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, ThailandBackground: Curcumin, the active ingredient from turmeric rhizomes, has been shown to have a wide range of pharmacological properties including antioxidant and anti-inflammatory effects. Curcumin has been reviewed for its multiple molecular action on inhibiting tumor angiogenesis via its mechanisms of cyclooxygenase (COX)-2, and vascular endothelial growth factor (VEGF) inhibition. In this present study, we aimed to assess the effects of curcumin on preventing diabetes-induced vascular dysfunction in association with COX-2, nuclear factor-κB (NF-κB) expression, and prostanoid production.Methods: Twelve-week-old male Wistar rats were separated into five groups: 1) diabetes with 0.9% normal saline (DM-NSS; n = 10), 2) diabetes treated with curcumin 30 mg/kg (n = 10), 3) diabetes treated with curcumin 300 mg/kg (n = 10), 4) the control with 0.9% normal saline (n = 10), and 5) the control treated with 300 mg/kg (n = 10). Daily oral feeding of curcumin was started at 6 weeks after the streptozotocin injection. Levels of 6-keto prostaglandin (PG) F1α and thromboxane (TX) B2 were determined from mesenteric perfusates using enzyme immunoassay kits. Protein kinase C (PKC)-ßII and COX-2 with NF-κB levels were analyzed in the mesenteric arteries by immunofluorescent staining and immunohistochemistry, respectively.Results: The ratio of 6-keto-PGF1α and TXB2 was significantly decreased in DM-NSS compared with the control (P < 0.05). Double-immunofluorescent staining with specific antibodies for PKC-βII and a-smooth muscle actins showed that the diabetic mesenteric arteries contained increased of PKC-βII within the vascular wall. Also, COX-2 expression and activated NF-κB in the small mesenteric artery of diabetes mellitus rats were markedly increased when compared with the control. Interestingly, curcumin could inhibit the upregulation of all of these biomarkers.Conclusion: These findings show that curcumin can attenuate diabetes-induced vascular dysfunction in association with its potential for COX-2 and NF-κB suppression, PKC inhibition, and improving the ratio of prostanoid products PGI2/TXA2.Keywords: diabetes, endothelial dysfunction, COX-2, prostanoid

Curcumin supplementation could improve diabetes-induced endothelial dysfunction associated with decreased vascular superoxide production and PKC inhibition

<p>Abstract</p> <p>Background</p> <p>Curcumin, an Asian spice and food-coloring agent, is known for its anti-oxidant properties. We propose that curcumin can improve diabetes-induced endothelial dysfunction through superoxide reduction.</p> <p>Methods</p> <p>Diabetes (DM) was induced in rats by streptozotocin (STZ). Daily curcumin oral feeding was started six weeks after the STZ injection. Twelve weeks after STZ injection, mesenteric arteriolar responses were recorded in real time using intravital fluorescence videomicroscopy. Superoxide and vascular protein kinase C (PKC-βII) were examined by hydroethidine and immunofluorescence, respectively.</p> <p>Results</p> <p>The dilatory response to acetylcholine (ACh) significantly decreased in DM arterioles as compared to control arterioles. There was no difference among groups when sodium nitroprusside (SNP) was used. ACh responses were significantly improved by both low and high doses (30 and 300 mg/kg, respectively) of curcumin supplementation. An oxygen radical-sensitive fluorescent probe, hydroethidine, was used to detect intracellular superoxide anion (O₂^●-) production. O₂^●-production was markedly increased in DM arterioles, but it was significantly reduced by supplementation of either low or high doses of curcumin. In addition, with a high dose of curcumin, diabetes-induced vascular PKC-βII expression was diminished.</p> <p>Conclusion</p> <p>Therefore, it is suggested that curcumin supplementation could improve diabetes-induced endothelial dysfunction significantly in relation to its potential to decrease superoxide production and PKC inhibition.</p

Factors affecting adhesion of polymers during coinjection

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Curcumin improves prostanoid ratio in diabetic mesenteric arteries associated with cyclooxygenase-2 and NF-&amp;kappa;B suppression

Sirada Rungseesantivanon1, Naris Thengchaisri4, Preecha Ruangvejvorachai2, Suthiluk Patumraj31Interdepartment of Physiology, Graduate School, 2Department of Pathology, 3Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; 4Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, ThailandBackground: Curcumin, the active ingredient from turmeric rhizomes, has been shown to have a wide range of pharmacological properties including antioxidant and anti-inflammatory effects. Curcumin has been reviewed for its multiple molecular action on inhibiting tumor angiogenesis via its mechanisms of cyclooxygenase (COX)-2, and vascular endothelial growth factor (VEGF) inhibition. In this present study, we aimed to assess the effects of curcumin on preventing diabetes-induced vascular dysfunction in association with COX-2, nuclear factor-&amp;kappa;B (NF-&amp;kappa;B) expression, and prostanoid production.Methods: Twelve-week-old male Wistar rats were separated into five groups: 1) diabetes with 0.9% normal saline (DM-NSS; n = 10), 2) diabetes treated with curcumin 30 mg/kg (n = 10), 3) diabetes treated with curcumin 300 mg/kg (n = 10), 4) the control with 0.9% normal saline (n = 10), and 5) the control treated with 300 mg/kg (n = 10). Daily oral feeding of curcumin was started at 6 weeks after the streptozotocin injection. Levels of 6-keto prostaglandin (PG) F1&amp;alpha; and thromboxane (TX) B2 were determined from mesenteric perfusates using enzyme immunoassay kits. Protein kinase C (PKC)-&amp;szlig;II and COX-2 with NF-&amp;kappa;B levels were analyzed in the mesenteric arteries by immunofluorescent staining and immunohistochemistry, respectively.Results: The ratio of 6-keto-PGF1&amp;alpha; and TXB2 was significantly decreased in DM-NSS compared with the control (P &amp;lt; 0.05). Double-immunofluorescent staining with specific antibodies for PKC-&amp;beta;II and a-smooth muscle actins showed that the diabetic mesenteric arteries contained increased of PKC-&amp;beta;II within the vascular wall. Also, COX-2 expression and activated NF-&amp;kappa;B in the small mesenteric artery of diabetes mellitus rats were markedly increased when compared with the control. Interestingly, curcumin could inhibit the upregulation of all of these biomarkers.Conclusion: These findings show that curcumin can attenuate diabetes-induced vascular dysfunction in association with its potential for COX-2 and NF-&amp;kappa;B suppression, PKC inhibition, and improving the ratio of prostanoid products PGI2/TXA2.Keywords: diabetes, endothelial dysfunction, COX-2, prostanoid