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Perylene derivatives are industrially important pigments used not only as colorants, but also as materials for optical disks and photoconductors for electrophotographic photoreceptors. These pigments cover a variety of shades in the solid state from vivid red, via maroon to black, although their molecular absorption spectra are quite similar in solution. The color generation mechanism has therefore been investigated in three representative pigments (PR149, PR179, and PB31) with special attention to the crystal structure and intermolecular interactions. The color in the solid state is mostly determined by two absorption bands in the visible region:  one is of molecular character and is due to nonresonance interactions, whereas the other is caused by interactions between transition dipoles. The red color (PR149) appears as a result of insignificant resonance interactions, whereas the colors of maroon (PR179) and black (PB31) are characterized by medium and strong interactions, respectively.

Bone morphogenetic protein (BMP)-6 is a member of the transforming growth factor (TGF)-(β) superfamily, and is most similar to BMP-5, osteogenic protein (OP)-1/BMP-7, and OP-2/BMP-8. In the present study, we characterized the endogenous BMP-6 signaling pathway during osteoblast differentiation. BMP-6 strongly induced alkaline phosphatase (ALP) activity in cells of osteoblast lineage, including C2C12 cells, MC3T3-E1 cells, and ROB-C26 cells. The profile of binding of BMP-6 to type I and type II receptors was similar to that of OP-1/BMP-7 in C2C12 cells and MC3T3-E1 cells; BMP-6 strongly bound to activin receptor-like kinase (ALK)-2 (also termed ActR-I), together with type II receptors, i.e. BMP type II receptor (BMPR-II) and activin type II receptor (ActR-II). In addition, BMP-6 weakly bound to BMPR-IA (ALK-3), to which BMP-2 also bound. In contrast, binding of BMP-6 to BMPR-IB (ALK-6), and less efficiently to ALK-2 and BMPR-IA, together with BMPR-II was detected in ROB-C26 cells. Intracellular signalling was further studied using C2C12 and MC3T3-E1 cells. Among the receptor-regulated Smads activated by BMP receptors, BMP-6 strongly induced phosphorylation and nuclear accumulation of Smad5, and less efficiently those of Smad1. However, Smad8 was constitutively phosphorylated, and no further phosphorylation or nuclear accumulation of Smad8 by BMP-6 was observed. These findings indicate that in the process of differentiation to osteoblasts, BMP-6 binds to ALK-2 as well as other type I receptors, and transduces signals mainly through Smad5 and possibly through Smad1.

The objective of this investigation was to quantitate the effect of binding on the iontophoretic transport of a series of amino acids. The diffusivity and concentration in the stratum corneum and viable skin were estimated from the passive permeation profiles through whole and stripped skin. Using these parameters and the Langmuir binding parameters from equilibrium binding studies, the passive permeation and desorption profiles were simulated using a bilayer skin permeation model. The parameters were adjusted until convergence with experimental data was achieved. Then the iontophoretic profiles were simulated, using the parameters from the simulated passive permeation studies, an estimate of convective flow from the flux of tritiated water, and measurement of the potential across the skin. The overall effect of binding on the iontophoretic profiles was found to dampen the effect of the iontophoresis treatment; the profiles appear flatter, and the transition to passive diffusion less distinct compared to profiles which do not include the binding parameters. It also appears that the degree of skin hydration has a substantial effect on the shape of the iontophoretic profile, such that approximately 50% of the enhancement in the iontophoretic profile of freshly excised skin continues after treatment.

Advances in techniques in molecular biology have facilitated the research into endogenous opioids and related peptides in several ways. The organization and expression of genes and the primary structure of three precursor proteins of opioid peptides have been elucidated. These studies predicted the presence of potentially bioactive peptides, which has been confirmed by later studies. Advances in techniques in protein chemistry have helped to elucidate the distribution and molecular forms of endogenous opioids and related peptides in the body, and the processing of precursor proteins. Studies on the function of these peptides have shown a broad spectrum of actions. Leumorphin, a newly identified peptide, has been shown to exhibit unique biological activities. In spite of extensive studies, the physiological and pathophysiological significance of opioid peptide systems are not yet completely understood. This is mainly due to the paucity of our knowledge about opioid receptors. Further studies on the subtypes of opioid receptors will help to elucidate all aspects of the function of endogenous opioids and related peptides.J. Endocr.(1985) 107,147–157

The release kinetics of lipophilic drug from hydrophobic polymer-based matrix-type drug delivery system was studied. Using the "intrinsic formula", several experimental problems can be analyzed and solved. The results reveal that intrinsic release, calculated from the model, shows the true properties of the drug delivery system, which might have been disguised by the boundary layer effect. The results also demonstrated the needs of maintaining sink condition and uniform distribution of dispersed phase in studying the matrix diffusion-controlled drug release.

A theoretical non-steady-state treatment was developed to analyze the kinetics of metabolism during the course of dermal uptake or skin permeation of estradiol esters across the hairless mouse skin. The first-order rate constants for the metabolism reaction of estradiol acetate → estradiol and estradiol diacetate → estradiol acetate → estradiol were determined. The theoretical drug concentration profile calculated from the present model was found to be agreed reasonably well with the experimental data determined in the early stage of skin uptake/metabolism studies (<24 hr). For the skin permeation of estradiol acetate and diacetate and their concurrent metabolism, the experimental Q vs. t profiles were also observed to agree well with the theoretical results for a period of up to 28 hr. A deviation was observed at later phase of experiments, which can be attributed to the reduction in enzyme activity during the permeation studies, possibly due to the result of skin aging.

The mixing time required to achieve 99.5% of homogeneous concentration in a vibratory disk tank has been measured by a pulse injection method of NaCI solution. The mixing time, tm has been well correlated bywhere D is the tank inside diameter, Pw, the power requirement per unit volume, V the tank volume, A the amplitude of disk vibration, f the frequency, p the liquid density and d the disk diameter. It is also found that liquid mixing in the vibratory disk tank is mainly controlled by turbulent mixing phenomena rather than by convective flow.

The hydrophilicity of progesterone, a lipophilic steroid itself, was progressively increased by incorporating one or more hydroxy substituents at different positions on the steroidal skeleton. Effects of these hydrophilic substituents on the permeation of progesterone across the intact skin and stripped skin of the hairless mouse were studied using a hydrodynamically well-calibrated in vitro skin permeation system. The steady-state rate of permeation across the intact skin and stripped skin was found to be approximately proportional to the solubility of drugs in the stratum corneum or in the viable skin, respectively. Furthermore, the solubility of progesterone and its hydroxyl derivatives in the stratum corneum was noted to decrease gradually as the hydrophilicity of the penetrant increased. This finding was similar to that of a previously reported study of drug permeation across the lipophilic silicone membrane. However, the solubility of these progestins in the viable skin was observed to be dependent not only on the penetrant hydrophilicity but also on the position of the OH group on the penetrant molecule. The diffusivity of progesterone and its hydroxyl derivatives across the stratum corneum and viable skin was almost independent of the hydrophilicity of the drugs.

Small fatigue crack growth in 7075-T651 aluminum is periodically monitored with an ultrasonic Rayleigh wave technique. The wideband reflection signals are digitized and stored in the computer memory to permit the signal processing in the frequency domain. With the help of the constructed three-dimensional (3-D) reflection coefficient, the reflection amplitude spectra yield the measurements of the crack depth, if larger than 0.062 mm, and the crack closure stress. Acoustically obtainedda/dN-ΔKeffrelations describe the anomalous growth behavior of small surface crack, extending from the late small crack regime to the large crack regime passing through the minimum growth rate. The split spectrum processing proves to be useful in removing the grain noises to illuminate the target echoes, which is necessary to detect the nucleation and characterize the cracks smaller than 0.1 mm in depth. Discussions on the computer-controlled, automated,in situmonitoring system are provided.