Somatostatin Inhibits Cell Migration and Reduces Cell Counts of Human Keratinocytes and Delays Epidermal Wound Healing in an Ex Vivo Wound Model

The peptide hormone somatostatin (SST) and its five G protein-coupled receptors (SSTR1-5) were described to be present in the skin, but their cutaneous function(s) and skin-specific signalling mechanisms are widely unknown. By using receptor specific agonists we show here that the SSTRs expressed in keratinocytes are functionally coupled to the inhibition of adenylate cyclase. In addition, treatment with SSTR4 and SSTR5/1 specific agonists significantly influences the MAP kinase signalling pathway. As epidermal hormone receptors in general are known to regulate re-epithelialization following skin injury, we investigated the effect of SST on cell counts and migration of human keratinocytes. Our results demonstrate a significant inhibition of cell migration and reduction of cell counts by SST. We do not observe an effect on apoptosis and necrosis. Analysis of signalling pathways showed that somatostatin inhibits cell migration independent of its effect on cAMP. Migrating keratinocytes treated with SST show altered cytoskeleton dynamics with delayed lamellipodia formation. Furthermore, the activity of the small GTPase Rac1 is diminished, providing evidence for the control of the actin cytoskeleton by somatostatin receptors in keratinocytes. While activation of all receptors leads to redundant effects on cell migration, only treatment with a SSTR5/1 specific agonist resulted in decreased cell counts. In accordance with reduced cell counts and impaired migration we observe delayed re-epithelialization in an ex vivo wound healing model. Consequently, our experiments suggest SST as a negative regulator of epidermal wound healing

Are Retailers’ Private Labels Always Detrimental to National Brand Manufacturers? A Differential Game Perspective

We study the competition between national and private brands (or private labels) in a vertical channel structure. Our main objective is to analyze the impacts of the private label’s existence on strategies, sales, and profits of the members and the whole channel. We use a differential game, where the control variables are price and non-price marketing decisions, and investigate two scenarios. The first one, used as a benchmark, considers an exclusive retailer that distributes only a national brand provided by a manufacturer. The latter invests in national advertising to build its brand’s goodwill. In the second scenario, the retailer owns a private label that competes with the national brand. By computing the results under both scenarios, we provide answers to the following research questions: (1) What should the price and the non-price marketing strategies be, with and without the private label? (2) How do they compare? (3) Is the presence of a private label always profitable for the retailer and harmful to the manufacturer? One of our main results indicates that the manufacturer is not necessarily always hurt by the private label, as the existing literature suggests

Dynamic models of the firm with green energy and goodwill with a constant size of the output market

This paper analyzes a dynamic model of the firm. We focus on the effect of investment in green energy. We explicitly take into account that green energy has a positive side effect, namely that it contributes to the goodwill of the firm and thus increases demand. Different models are proposed and the solutions range from monotonic saddle point convergence to history-dependent Skiba behavior