The mechanism by which ultraviolet radiation induces melanogenesis in epidermal melanocytes is unknown. Previous observations that in cultured human melanocytes 1-oleoyl-2-acetylglycerol augmented both basal and ultraviolet radiation-induced melanogenesis, suggested that the responses were mediated via protein kinase C. However, paradoxically the phorbol ester TPA was without effect. Therefore,...

Target inactivation analysis was used to determine the functional size of the charybdotoxin (ChTX) receptor in aortic and tracheal sarcolemmal membrane vesicles. This receptor has previously been shown to be an integral component of the high-conductance Ca2+-activated K+ (Maxi-K) channel in these smooth muscles. Exposure of either bovine aortic or bovine tracheal sarcolemma to high-energy irrad...

Recent investigations provided evidence that the sphingomyelin signal transduction pathway mediates apoptosis for tumor necrosis factor alpha (TNF-alpha) in several hematopoietic and nonhematopoietic cells. In this pathway, TNF-receptor interaction initiates sphingomyelin hydrolysis to ceramide by a sphingomyelinase. Ceramide acts as a second messenger stimulating a ceramide-activated serine/th...

Background: The threat of a terrorist-precipitated nuclear event places humans at risk for

This paper describes the construction and calibration of the NIST large area x-ray counting system. 238Pu sources 8 in (20.32 cm) by 5 in (12.70 cm) thick, emitting L x rays in the range of 12-20 keV are calibrated for total emission rate and also for rate through a centrally located 3 in (7.63 cm) diameter aperture. Alpha particle emission rates are obtained using the known x-ray to alpha part...

Manganous superoxide dismutase (MnSOD) scavenges potentially toxic superoxide radicals produced in the mitochondria. Tumor necrosis factor-alpha (TNF-alpha) was found to induce the messenger RNA for MnSOD, but not the mRNAs for other antioxidant or mitochondrial enzymes tested. The increase in MnSOD mRNA occurred rapidly and was blocked by actinomycin D, but not by cycloheximide. Induction of M...