Melanogenic Regulatory Factors in Coated Vesicles from Melanoma Cells

Coated vesicles have been found to contain much higher tyrosinase and γ-glutamyl transpeptidase activities than pre-melanosomes. This indicates that similar to tyrosinase, γ-glutamyl transpeptidase, an enzyme responsible for pheomelanogenesis, is highly concentrated in coated vesicles after its maturation in Golgi associated endoplasmic reticulum (GERL). Furthermore, in the pre- and post-dopaquinone melanogenic pathway, coated vesicles convert dopachrome to colorless indole compounds mere quickly than in premelanosomes because of their higher dopachrome conversion factor activity. Melanosomes have been found to exhibit indole conversion factor activity, while coated vesicles show indole blocking factor activity. In moderately tyrosinase-rich premelanosomes, the levels of dopachrome conversion factor and indole blocking factor are lower than in coated vesicles or melanosomes. High levels of indole blocking factor in coated vesicles may indicate why melanin polymer formation does not occur there in vivo despite their high tyrosinase activity

Expression of Proopiomelanocortin, Corticotropin-Releasing Hormone (CRH), and CRH Receptor in Melanoma Cells, Nevus Cells, and Normal Human Melanocytes

Proopiomelanocortin (POMC) is a 31kDa prohormone that is processed to various bioactive peptides, including adrenocorticotropin (ACTH), melanotropins (α, β, γ-MSH), lipotropins, and endorphins. POMC is expressed not only in the pituitary gland but also in a variety of nonpituitary organs and tumors, including melanomas. We previously showed that normal human melanocytes produce and secrete α-MSH and ACTH, and furthermore, that advanced melanoma cells generally produce higher amounts of POMC peptides that correlate with tumor progression. To elucidate the mechanism of this upregulation, the expression of genes encoding corticotropin-releasing hormone (CRH) and its receptor, CRHR, as well as POMC and the MSH receptor (MC1-R), was evaluated by reverse transcriptase-polymerase chain reaction using cultured human melanoma cells, nevus cells, and normal melanocytes. Our results show that all melanocytic cells express CRH, CRH-R, POMC, and MC1-R, with highest intensities in melanoma cells. Furthermore, immunohistochemistry shows that CRH as well as POMC is strongly expressed in advanced melanomas, such as vertically growing lesions of acral lentiginous, nodular and metastatic melanomas, in contrast to negative expression in nevus cells. These results indicate that tumor progression accentuates CRH, CRH-R, and POMC expression by melanoma cells

Hemodynamic characteristics in aorta-pulmonary artery system

The child patients of hypoplastic left heart syndrome undergoes major operations such as the Norwood procedure, the Bidirectional Glenn procedure and the Fontan procedure. Patent Ductus Arteriosus (PDA) stenting, which is instead of these procedures, is recently performed to prevent closure of ductus arteriosus and to alleviate the burden for the patient. This study clarified that hemodynamics in aorta-pulmonary artery system and mechanism of thrombus formation using Computational Fluid Dynamics (CFD) analysis and Particle Imaging Velocimetry (PIV) measurement. As a result of CFD analysis, low wall shear stress was observed at neighborhood of PDA stent. From results of CFD analysis and PIV measurement, the main blood flow was formed toward from aorta to pulmonary artery and there is no blood stagnation region in PDA

Excitation and relaxation in atom-cluster collisions

Electronic and vibrational degrees of freedom in atom-cluster collisions are treated simultaneously and self-consistently by combining time-dependent density functional theory with classical molecular dynamics. The gradual change of the excitation mechanisms (electronic and vibrational) as well as the related relaxation phenomena (phase transitions and fragmentation) are studied in a common framework as a function of the impact energy (eV...MeV). Cluster "transparency" characterized by practically undisturbed atom-cluster penetration is predicted to be an important reaction mechanism within a particular window of impact energies.Comment: RevTeX (4 pages, 4 figures included with epsf