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This work evaluates the effect of carbon nanotube (CNT) addition to plasma-sprayed hydroxyapatite (HA) coating on its tribological behavior, biocompatibility of the coating, and cytotoxicity of CNT-containing wear debris. Biological response of the CNT-containing wear debris is critical for osteoblasts, the bone-forming cells, and macrophages, the cells that clear up wear debris from blood stream. The addition of 4 wt % CNTs to HA coating reduces the volume of wear debris generation by 80% because of the improved elastic modulus and fracture toughness. CNT reinforcement has a pronounced effect on the particle size in the wear debris and subsequent biological response. There was a slight increase in the numbers and viability of osteoblasts grown on HA-CNT compared with HA alone. The cytotoxic effect of HA and HA-CNT debris to macrophages and osteoblasts was similar, demonstrating that loose CNT does not pose a problem to these cells. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. [ABSTRACT FROM AUTHOR]

Exercise is a mechanism for maintenance of body weight in humans. Morbidly obese human patients have been shown to possess single nucleotide polymorphisms in the melanocortin-4 receptor (MCAR). MC4R knockout mice have been well characterized as genetic: model that possesses phenotypic metabolic disorders, including obesity, hyperphagia, hyperinsulinemia, and hyperleptinemia, similar to those observed in humans possessing dysfunctional hMC4Rs. Using this model, we examined the effect of voluntary exercise MC4R knockout mice that were allowed access to running wheel for a duration of 8 wk. Physiological parameters that were measured included body weight, body composition of fat and lean mass, food consumption, body length, and blood levels of cholesterol and nonfasted glucose, insulin, and leptin. At the termination of the experiment, hypothalamic mRNA expression levels of neuropeptide Y (NPY), agouti-related protein (AGRP), proopiomelanocorlin (POMC), cocaine- and amphetamine-regulated transcript (CART), orexin, brain-derived neurotropic factor (BDNF), phosphatase with tensin homology (Pten), melanocortin-3 receptor (MC3R), and NPY-Y1R were determined. In addition, islet cell distribution and function in the pancreas were examined. In the exercising MC4R knockout mice, the pancreatic islet cell morphology and other physiological parameters resembled those observed in the wild-type littermate controls. Gene expression profiles identified exercise as having a significant effect on hypothalamic POMC, orexin, and MC3R levels. Genotype had a significant effect on AGRP, POMC, CART, and NPY-Y1R, with an exercise and genotype interaction effect on NPY gene expression. These data support the hypothesis that voluntary exercise can prevent the genetic predisposition of melanocortin-4 receptor-associated obesity and diabetes. [ABSTRACT FROM AUTHOR]

ATP-binding cassette (ABC) transporters play a pivotal role in physiology and pathology. We identified and cloned two novel mRNA isoforms (ABCB 5α andABCB 5β) of the ABC transporterABCB 5 in human melanoma cells. The deducedABCB 5α protein appears to be an altered splice variant containing only a putative ABC, whereas theABCB 5β isoform shares approximately 70% similarity withABCB1 (MDR1) and has a deduced topological arrangement similar to that of the whole carboxyl terminal half of theABCB1 gene product, P-glycoprotein, including an intact ABC. Northern blot, real-time PCR, and conventional RT-PCR were used to verify the expression profiles ofABCB 5α/β. We found that the melanomas included among the NCI-60 panel of cell lines preferentially expressed bothABCB 5α andABCB 5β. However,ABCB 5α/β expression was undetectable in two amelanotic melanomas (M14 and LOX-IMVI). The expression profile ofABCB 5α/β in all of the other melanomas of the panel was confirmed both by RT-PCR and by sequencing. NeitherABCB 5α norABCB 5β expression was found in normal tissues such as liver, spleen, thymus, kidney, lung, colon, small intestines or placenta.ABCB 5α/β mRNAs were also expressed in normal melanocytes and in retinal pigment epithelial cells, suggesting thatABCB 5α/β expression is pigment cell-specific and might be involved in melanogenesis. Our findings indicate that expression ofABCB 5α/β might possibly provide two novel molecular markers for differential diagnosis of melanomas and constitute potential molecular targets for therapy of melanomas. [ABSTRACT FROM AUTHOR]