"Direct" grafting of linear macromolecular "wedges" to the edge of pristine graphite to prepare edge-functionalized graphene-based polymer composites

The edges of pristine graphite were covalently grafted with para-poly(ether-ketone) (pPEK) in a mildly acidic polyphosphoric acid (PPA)/phosphorus pentoxide (P(2)O(5)) medium. The resulting pPEK grafted graphite (pPEK-g-graphite) showed that the pristine graphite had been exfoliated into a few layers of graphene platelets (graphene-like sheets), which were uniformly dispersed into a pPEK matrix. As a result, the tensile properties of pPEK-g-graphite films were greatly improved compared to those of controlled pPEK films. The origins of these enhanced mechanical properties were deduced from scanning electron microscope (SEM) images of fracture surfaces. Upon tracing wide-angle X-ray scattering (WAXS) patterns of the film under strain, the graphene-like sheets were further exfoliated by an applied shear force, suggesting that a toughening mechanism for the pPEK-g-graphite film occurred. This approach envisions that the "direct'' edge grafting of pristine graphite without pre-treatments such as corrosive oxidation and/or destructive sonication is a simple and efficient method to prepare graphene-based polymer composites with enhanced mechanical properties.close161

Pharmacokinetics of Amitriptyline Demethylation;A Crossover Study with Single Doses of Amitriptyline and Nortriptyline

A single dose crossover pharmacokinetic study of amitriptyline and nortriptyline was done to find out the extent of first-pass metabolism to nortriptyline after amitripyline administration, and the contribution of nortriptyline during amitriptyline therapy. Six healthy male volunteers took part in this study and were given single doses (50 mg) of amitriptyline and nortriptyline at more than three-week intervals. Plasma concentrations of the drugs were measured up to 48 hours. Total area under the plasma concentration-time curve (AUe) of amitriptyline (744.6±258.4 ng/ml·hl was smaller than that of nortriptyline (l497.3±589.8 ng/ml'h), and the mean terminal half-life of amitriptyline (21.8±3.9 hr) was shorter than that of nortriptyline (36.8±5.9 h). The total area under the plasma concentration-time curve of nortriptyline produced by amitriptyline administration was 498.1 ±274.5 ng/ml·h, and the fraction produced by the first-pass of amitriptyline was 33.7 ± 10.5%. From this data, it can be estimated that the average nortriptyline concentration could be about 40% of the total tricyclic antidepressants present in the plasma of patients taking multiple amitriptyline therapy at steady state. About 34% of nortriptyline is produced by first- pass effect during gastrointestinal absorption of amitriptyline to systemic circulation resulting from N-demethylation of amitriptyline in the liver. Then, the rest of the nortriptyline is formed continuously at a rate proportional to the rate of amitriptyline elimination

Results of immediate loading for implant restoration in partially edentulous patients: a 6-month preliminary prospective study using SinusQuick™ EB implant system

STATEMENT OF PROBLEM. Many dental clinicians are concerned about immediate loading of inserted implants. However, there have been few clinical studies surveying the success rates of immediate loading, based on Korean implant systems. PURPOSE. The aim of this study was to evaluate the outcome of immediate functional loading of the implant (SinusQuickTM EB, Neobiotech Co., Seoul, Korea) in partially edentulous maxilla or mandible. MATERIAL AND METHODS. Total 15 implants were placed. Within 2 weeks after implant insertion, provisional implant-supported fixed partial dentures were delivered to the patients. Quantitatively, marginal bone loss was measured at the time of immediate loading, after 3-months of continued loading and at the last follow-up. The mean follow-up period was 4.8 months. RESULTS. Mean marginal bone loss from implant surgery to early loading, 3-months follow-up and last follow-up was 0.03 ± 0.07 mm, 0.16 ± 0.17 mm and 0.29 ± 0.19 mm. No implant failed up to 6 months after insertion, resulting in a 100% survival rate. CONCLUSION. Immediate loading exhibited high success rate in partial edentulism for up to 6 months. Well-controlled long term clinical studies with large sample size are necessary to confirm this finding

Hemorrhagic Transformation of Ischemic Stroke: Severe Complications of Prosthetic Valve Endocarditis

Ischemic stroke is a common complication of infective endocarditis (IE), occurring in 20-40% of left side IE cases. In these subsets, anticoagulation therapy may provoke hemorrhagic transformation (HT) of ischemic stroke, and complications of this magnitude deteriorate the clinical course for IE patients. However, in cases of IE complicated with a mechanical prosthetic valve, the physician can be concerned over the maintenance of anticoagulation due to the risk of thrombotic complication. According to our retrospective review, HT of ischemic stroke in prosthetic valve endocarditis occurred 13.8% (4/29) of the time in a variety of situations. Some of these even arose in patients with a subtherapeutic range of prothrombin time

Improved blastocyst development of single cow OPU-derived presumptive zygotes by group culture with agarose-embedded helper embryos

<p>Abstract</p> <p>Background</p> <p>The <it>in vitro </it>culture of presumed zygotes derived from single cow ovum pick-up (OPU) is important for the production of quality blastocysts maintaining pedigree. The aim of the present study was to evaluate the agar chip-embedded helper embryo coculture system for single cow OPU-derived zygotes by assessing embryo quality.</p> <p>Methods</p> <p>Cumulus oocyte complexes (COCs) were collected from Hanwoo cows with high genetic merit twice a week using the ultra-sound guided OPU technique and from slaughterhouse ovaries. The Hanwoo cow COCs and slaughterhouse ovaries were matured <it>in vitro</it>, fertilized <it>in vitro </it>with thawed Hanwoo sperm and cultured for 24 h. The presumed zygotes were subsequently placed in three different culture systems: (1) control OPU (controlOPU) with single cow OPU-derived presumed zygotes (2~8); (2) agar chip-embedded slaughterhouse helper embryo coculture (agarOPU) with ten presumed zygotes including all presumed zygotes from a cow (2~8) and the rest from agar chip-embedded slaughterhouse presumed zygotes (8~2); and (3) slaughterhouse <it>in vitro </it>embryo production (sIVP) with ten slaughterhouse ovary-derived presumed zygotes, each in 50 μL droplets. Day 8 blastocysts were assayed for apoptosis and gene expression using real time PCR.</p> <p>Results</p> <p>The coculture system promoted higher blastocyst development in OPU zygotes compared to control OPU zygotes cultured alone (35.2 vs. 13.9%; P < 0.01). Genes predicted to be involved in implantation failure and/or embryo resorption were down-regulated (P < 0.05) in control OPU zygotes (<it>CD9</it>, 0.4-fold; <it>AKRAB</it>1, 0.3-fold) and in cocultured zygotes (<it>CD9</it>, 0.3-fold; <it>AKRAB</it>1, 0.3-fold) compared to sIVP blastocysts (1.0-fold). Moreover, genes involved in implantation and/or normal calf delivery were up-regulated (P < 0.05 to P < 0.01) in control OPU zygotes (<it>PGSH</it>2, 5.0-fold; <it>TXN</it>, 4.3-fold; <it>PLAU</it>, 1.7-fold) and cocultured zygotes (<it>PGSH</it>2, 14.5-fold; <it>TXN</it>, 3.2-fold; <it>PLAU</it>, 6.8-fold) compared to sIVP (1.0-fold) blastocysts. However, the expression of <it>PLAC8, TGF-β1, ODC1</it>, <it>ATP5A1 </it>and <it>CASP3 </it>did not differ between the three culture groups.</p> <p>Conclusions</p> <p>Results show that the agar chip-embedded helper embryo coculture system enhances developmental competence and embryo quality in cultures of limited numbers of high pedigree single cow OPU presumed zygotes.</p