Experimental Investigation of the Peel Strength of Artificial Leather and Polypropylene Specimens

This study investigates the surface properties and adhesive strength of polypropylene (PP) in order to enhance the bond between PP injection-molded specimens and polyvinyl chloride (PVC) synthetic artificial leather. Plasma, primer, and flame treatments were applied to the surface of each specimen prepared using the two types of injection molds. The surface morphology, surface roughness, and contact angle were analyzed, and peel-strength analyses and a morphological inspections of the peeled specimens were performed. The peeling strength of the PP injection molding was measured, followed by a morphological examination of the peeled specimens. The plasma and flame treatments improved the peel strength, and the plasma and flame treatments changed the rough exterior to a hydrophilic surface, improving the peel strength. In addition, the primer treatment exhibited a lower peel strength than did the other treatments. This confirmed the low adhesion of the primer to the hydrophobic PP surface. The outcomes of this study can be employed across a multitude of industries that require improved adhesion for PP injection molded products.

Effects of Annealing for Strength Enhancement of FDM 3D-Printed ABS Reinforced with Recycled Carbon Fiber

This study investigates the effect of annealing on the mechanical properties of fused deposition modeling (FDM) 3D-printed recycled carbon fiber (rCF)-reinforced composites. In this study, filaments for FDM 3D printers are self-fabricated from pure acrylonitrile butadiene styrene (ABS) and ABS reinforced with fiber content of 10 wt% and 20 wt% rCF. This study explores the tensile and flexural properties as a function of the annealing temperature and time for the three different fiber content values. In addition, dimensional measurements of the shape changes are performed to determine the suitability of applying annealing in practical manufacturing processes. The results show that annealing improves the mechanical properties by narrowing the voids between the beads, which occur during the FDM process, and by reducing the gaps between the fibers and polymer. Following annealing, the largest tensile and flexural strength improvements are 12.64% and 42.33%, respectively, for the 20 wt% rCF content samples. Moreover, compared with the pure ABS samples, the annealing effect improves the mechanical properties of the rCF-reinforced samples more effectively, and they have higher dimensional stability, indicating their suitability for annealing. These results are expected to expand the application fields of rCF and greatly increase the potential use of FDM-printed parts.

Characterization and optimization of vascular endothelial growth factor(165) (rhVEGF(165)) expression in Escherichia coli

Vascular endothelial growth factors(165) (VEGF(165)) is the most potent and widely used pro-angiogenic factor. Here we determined optimal culture condition of recombinant human VEGF(165) (rhVEGF(165)) in Escherichia coli (E. coli). rhVEGF(165) expression was the highest in 0.25% of L-arabinose induction concentration, at 20 °C induction temperature, and for 5 h induction time under the control of araBAD promoter using pBADHisA vector. In biological activity test, rhVEGF(165) significantly increased the proliferative activity of CPAE cells (p<0.001) and upregulated the expressions of endothelial cell growth-related genes, such as platelet endothelial cell adhesion molecule (PECAM-1), endothelial-specific receptor tyrosine kinase (TEK), kinase insert domain protein receptor (KDR), and tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (TIE1) in calf pulmonary artery endothelial (CPAE) cells.

Comparison of the efficacy of gemcitabine with capecitabine and gemcitabine with erlotinib combination chemotherapy in recurrent or advanced pancreatic cancer as first-line treatment: Single-center experience

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Background: We compared the efficacy and toxicity of gemcitabine with capecitabine (GX), and gemcitabine with erlotinib (GT) chemotherapy for recurrent or advanced pancreatic cancer by retrospective analysis.

Methods: Between October 2006 and June 2010, 44 patients with recurrent or advanced pancreatic cancer, diagnosed at Seoul St. Mary's hospital were enrolled. In GT group, gemcitabine 1000mg/m2 was administered on days 1, 8, 15, 22, 29, 36, 43 followed by a 1-week rest in first treatment cycle (8 weeks), and then D1, 8, 15 followed by a 1-week rest. Erlotinib was taken orally at 150mg daily through the entire cycle. In GX group, gemcitabine 1000mg/m2 was administered on days 1 and 8. Capecitabine was taken orally at 650mg/m2 twice daily on day 1-14 of a 21-day cycle.

Results: In 44 patients, 26 patients were treated with GT, and 18 patients treated with GX. The median age was 56.58 years in GT and 57.67 years in GX. Median number of cycle was 3.04 in GT and 3.57 in GX, and the dose reduction was significantly more common in GX than GT (50% vs. 19%, p=0.031). No complete response was achieved in either group. In GT, partial response and stable disease were achieved in 6 (23.1%) and 8 (30.8%) patients. In GX, partial response and stable disease were shown in 4 (22.2%) and 7 (38.9%) patients, respectively. No significant differences in two patients groups (p=0.442). GX had more favorable clinical outcome of the time to progression (6.1 months vs. 3.0 months, p=0.002) and the overall survival (11.13 months vs. 6.1 months, p=0.012) than GT. The most common grade 3 or 4 toxicity in GT and GX treatment were hematologic toxicity: anemia (8.3%:0%), neutropenia (34.6%:38.8%), thrombocytopenia (15.4%:11.1%). Grade 3 or 4 hand-foot-syndrome of GX was reported in only one patient.

Conclusions: GX showed better time to progression and overall survival outcome than GT, but dose reduction was more common. Although there was no significant difference in response rate, and the less dose intensity, GX regimen may be more effective than GT in advanced pancreatic cancer. Further prospective, randomized trials would be warranted in large scale.

No significant financial relationships to disclose.

Effect of tumor necrosis factor-alpha on experimental otitis media with effusion

OBJECTIVES/HYPOTHESIS

Up to the present, many reports have demonstrated that local immune response is associated with maintenance and persistence of effusion in the middle ear cavity. Resulting retention of inflammatory cells and mediators in the middle ear results in ongoing effusion. The purpose of this study was to clarify the role of tumor necrosis factor in experimental otitis media with effusion, which was induced by transtympanic injection of tumor necrosis factor in the rats.

STUDY DESIGN

Four groups were designed in two experiments. The purpose of experiment 1 was to confirm that transtympanic injection of TNF-alpha produces the middle ear effusion. In experiment 2, TNFsolRI was used to evaluate the possibility as an inhibitor in otitis media with effusion.

METHODS

The histopathological changes were observed under light microscope, and the changes in microvascular permeability were examined using Evans blue vital dye technique.

RESULTS

Middle ear effusion was developed in 70% of specimens, and histopathological changes, such as subepithelial edema and marked infiltration of neutrophils, were present in 100% at 24 hours after administration of tumor necrosis factor-alpha through transtympanic approach. Extravasation of Evans blue dye was found in all specimens injected by tumor necrosis factor-alpha, which was qualified using a fluorescence microscope and quantified using a spectrophotometer. These histopathological findings and changes in microvascular permeability were significantly reduced by tumor necrosis factor soluble receptor type I.

CONCLUSIONS

Neutrophil infiltration, subepithelial edema, increased microvascular permeability, and resultant effusion were indirectly proved to be induced by tumor necrosis factor-alpha. We hope that this study may contribute to understanding the role of tumor necrosis factor-alpha in otitis media with effusion and clarifying the future role of tumor necrosis factor soluble receptor type I in preventing otitis media with effusion.

Metabolism of VLDL is increased in streptozotocin-induced diabetic rat hearts

In streptozotocin (STZ)-induced diabetic rats, we previously showed an increased heparin-releasable (luminal) lipoprotein lipase (LPL) activity from perfused hearts. To study the effect of this enlarged LPL pool on triglyceride (TG)-rich lipoproteins, we examined the metabolism of very-low-density lipoprotein (VLDL) perfused through control and diabetic hearts. Diabetic rats had elevated TG levels compared with control. However, fasting for 16 h abolished this difference. When the plasma lipoprotein fraction of density <1.006 g/ml from fasted control and diabetic rats was incubated in vitro with purified bovine or rat LPL, VLDL from diabetic animals was hydrolyzed as proficiently as VLDL from control animals. Post-heparin plasma lipolytic activity was comparable in control and diabetic animals. However, perfusion of control and diabetic rats with heparinase indicated that diabetic hearts had larger amounts of LPL bound to heparan sulfate proteoglycan-binding sites. [(3)H]VLDL obtained from control rats, when recirculated through the isolated heart, disappeared at a significantly faster rate from diabetic than from control rat hearts. This increased VLDL-TG hydrolysis was essentially abolished by prior perfusion of the diabetic heart with heparin, implicating LPL in this process. These findings suggest that the enlarged LPL pool in the diabetic heart is present at a functionally relevant location (at the capillary lumen) and is capable of hydrolyzing VLDL. This could increase the delivery of free fatty acid to the heart, and the resultant metabolic changes could induce the subsequent cardiomyopathy that is observed in the chronic diabetic rat.