Influence of Inflammatory Mediators and Cytokines on Human Melanocyte Function

The fully differentiated human melanocyte functions as a necessary and integral part of the epidermis, synthesizing melanin in intracellular organelles and transferring these pigment-containing organelles to surrounding keratino-cytes. The epidermal environment contains multiple inflammatory mediators, cytokines, and growth factors that may alter constitutive melanocyte function. Constitutive melanocyte function can also be markedly altered by release of such mediators in inflammatory dermatoses. Many of the same factors can also be released by ultraviolet radiation and psoralen + ultraviolet A treatment. These inflammatory mediators and cytokines affect not only melanocyte pigment production, but also proliferation, differentiation, immunologic susceptibility and cytotoxicity, inflammatory mediator, cytokine and matrix protein production, and cell movement. The effect of inflammatory mediators and cytokines on melanocytes and the regulation of these effects are an active area of investigation. J Invest Dermatol 100:191S–195S, 199

Split Udder Comparison of Teat Disinfectants on Skin Toleration During Winter and Spring

The purpose this trial was to evaluate the skin toleration of a new experimental acidified sodium chlorite (ASC) barrier teat disinfectant compared to a standard nonbarrier chlorhexidine product with emollients (winter) and a high emollient, iodine barrier (spring) using a split-udder study to focus on the disinfectant effects as well as barrier teat dip issues in winter. Teat skin and end scores were similar between dips as long as the experimental dip was removed with good udder preparation prior to milking. Failure to remove the barrier dip resulted in poorer teat skin and end scores. This points out the necessity for good proper udder preparation premilking when barrier dips are used post milking

Making of the market: Oligopolistic business in Britain, 1945-c.1960.

The theory of the firm and transaction cost analysis provide the starting point of this institutional study of business co-operation in the aftermath of World War Two. It is suggested that the market is an institution which is subject to the visible hand of business. The aim of business in this process is to control information flows and reduce uncertainty. Utilising business history case studies, of the oil industry through the Anglo-Iranian Oil Co., the electrical engineering industry through General Electric Co. and the grocery retailing trade through J.Sainsbury, the hypothesis that the firm aims to create market governance procedures in order to alter the structure of the market is tested. The study finds that inter-firm co-operation is central to understanding the development of markets and that co-operation is a dynamic process, which responds to changes in market conditions and government competition policy. The growth of government as a consumer is considered to be a significant factor affecting the development of co-operative agreements between firms. The study also finds that collusion and co-operation between firms, leading to a reduction of competitive pressures, was central to the development of organisational capabilities in the oil and grocery retailing industries, but hindered the emergence of organisational capabilities within the electrical engineering industry. Finally, the study finds that the internalisation of market transactions occurs when market governance procedures break down and competition becomes intense. The study concludes that firms are not primarily transaction cost minimisers but are maximisers of market power. It is suggested that the maximising of market power is the rationale behind the creation of organisational capabilities and the development of the division of labour under conditions of supervision and discipline

Melanocyte Mitogens Induce Both Melanocyte Chemokinesis and Chemotaxis

It is believed that during repigmentation of vitiligo, inactive melanocytes in the outer root sheath of the hair follicle become activated, proliferate, and migrate into the depigmented skin. However, the mechanisms controlling melanocyte migration remain to be elucidated. In this study, we investigated the effects of well-described melanocyte growth factors on melanocyte migration. Using time-lapse photography, we demonstrated that melanocyte chemokinetic movement was induced by basic fibroblast growth factor, stem cell factor, and endothelin-1, with the greatest effect noted using 100 nM endothelin-1. Similar results were reported previously with leukotriene C4. When surrounded by these stimuli, melanocytes moved in a random, nonlinear fashion and showed no desensitization at the concentrations studied.In Boyden chamber checkerboard analysis, basic fibroblast growth factor, leukotriene C4 and endothelin-1 were chemotactic. They produced directional migration and showed desensitization at higher concentrations. The greatest effect again was seen with 100 nM endothelin-1. Stem cell factor showed no effect in this assay system at the concentrations tested.The four melanocyte mitogens-leukotriene C4, endothelin-1, basic fibroblast growth factor, and stem cell factor-stimulate melanocyte migration, and this migration may be either chemokinetic (activated random movement) or chemotactic (requiring a gradient, directional, and showing desensitization), depending on the conditions used. We believe that these factors may be effective in stimulating vitiligo repigmentation by inducing proliferation and migration of hair-follicle outer-root-sheath melanocytes into the depigmented epidermis

Suburban non-motorized access to transit : a framework for evaluation

Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 1998.Includes bibliographical references (p. 181-185).by Claude J. Morelli.M.C.P

Mendelian breeding units <i>versus</i> standard sampling strategies: mitochondrial DNA variation in southwest Sardinia

We report a sampling strategy based on Mendelian Breeding Units (MBUs), representing an interbreeding group of individuals sharing a common gene pool. The identification of MBUs is crucial for case-control experimental design in association studies. The aim of this work was to evaluate the possible existence of bias in terms of genetic variability and haplogroup frequencies in the MBU sample, due to severe sample selection. In order to reach this goal, the MBU sampling strategy was compared to a standard selection of individuals according to their surname and place of birth. We analysed mitochondrial DNA variation (first hypervariable segment and coding region) in unrelated healthy subjects from two different areas of Sardinia: the area around the town of Cabras and the western Campidano area. No statistically significant differences were observed when the two sampling methods were compared, indicating that the stringent sample selection needed to establish a MBU does not alter original genetic variability and haplogroup distribution. Therefore, the MBU sampling strategy can be considered a useful tool in association studies of complex traits

Identification of Functional Platelet-Activating Factor Receptors on Human Keratinocytes

Platelet-activating factor (PAP) is a potent inflammatory mediator that has been shown to be produced by human keratinocytes and is thought to play a role in cutaneous inflammation, Immunofluorescence and radioligand binding studies were used to characterize PAP receptors (PAF-R) on human keratinocytes and the human epidermoid cell lines A-431 and HaCaT. Indirect immunofluorescence studies demonstrated anti-PAF-R staining of primary cultures of human keratinocytes, A-431 cells, and HaCaT cells, Primary cultures of human fibroblasts and the melanoma cell line SK-30 failed to show immunostaining above that seen with control antiserum. With indirect immunofluorescence studies of sections of normal human skin, a granular anti-PAF-R staining pattern was noted on the keratinocyte cell membranes. A-431 cells readily metabolized PAF by deacetylationreacylation at 37°C, but not at 4°C. Binding studies on crude membrane preparations of A-431 cells conducted at 4°C demonstrated specific binding that reached saturation by 120 min. Scatchard analysis of PAF binding data revealed a single class of high-affinity (KD = 6.3 ± 0.3 nM) PAP binding sites, The immunofluorescence and radioligand binding sites were shown to be functional PAF-Rs, as 10 pM to 1 μM PAF increased intracellular calcium in primary cultures of human keratinocytes, A-.431 cells, and HaCaT cells, whereas PAF treatment of primary cultures of human fibroblasts or the melanoma cell line SK-30 did not result in changes in the intracellular calcium concentration. The structurally dissimilar PAF-R antagonists CV-6209, Ro19-3704, and alprazolam all inhibited the PAF-induced calcium changes in A-431 cells, The CV-6209 inhibition was seen at doses that competed with the PAF binding to these cells. These studies provide the first evidence for the presence of a functional PAF-R expressed on human keratinocytes, suggesting that this lipid mediator may play an important role in normal keratinocytes or in inflammatory dermatology

Full-Scale Prop-Rotor Stability Tests on the XV3 at High Advance Ratios

Tests in the 40-by-80 foot wind tunnel were made at airspeeds from 40 to 195 knots. The aircraft was mounted with and without roll freedom. Rotor pylon configuration variables included the following: swashplate stabilization by mechanically coupling the swashplate to the wing or fuselage; pylon restraint stiffness and damping; hub restraint; and delta-three combined with swashplate retardation. Time histories were recorded of pylon motions and rotor loads following pulse-type excitations of the pylon. It was found that damping of the low frequency whirl mode increased with swashplate stabilization, pylon stiffness, and hub restraint