Using permeabilized, arterial smooth muscle strips where membrane-associated pathways remain intact but intracellular Ca 2؉ stores are depleted, we investigated mechanism(s) for the Ca 2؉ desensitization of contractile force by cGMP. The nonhydrolyzable analog 8-bromo-cGMP, when applied to these strips with submaximal Ca 2؉ levels clamped, dramatically and reversibly reduced the steady state levels of phosphorylation at 20-kDa myosin light chain and contractile force, with a nanomolar concentration required to obtain 50% reduction. Supramaximal concentrations of 8-bromocGMP (10 M), however, did not change the steady state relationship between phosphorylation and force. When light chain phosphatase activity was blocked at pCa 6.7, 10 M 8-bromo-cGMP did not affect the rates of rise of light chain phosphorylation and contractile force. When light chain kinase activity was blocked, 10 M 8-bromocGMP significantly accelerated light chain dephosphorylation and force relaxation from the maximal contraction steady state. The light chain phosphorylation time course of a pCa 6.0-induced contraction in the presence of 8-bromo-cGMP exhibited kinetics that are predictable from a mathematical model in which only light chain phosphatase activity is increased. The results of this study strongly suggest that cGMP indirectly activates light chain phosphatase, the first proposed mechanism for cGMP-induced Ca 2؉ desensitization in vasodilatation.The primary mechanisms that regulate smooth muscle contraction and relaxation are, respectively, phosphorylation of the regulatory 20-kDa myosin light chain (MLC 20 ) 1 at Ser-19 by MLC 20 kinase (MLCK) and its dephosphorylation by MLC 20 phosphatase (MLCP) (1, 2). Typically, intracellular Ca 2ϩ levels modulate the MLCK to MLCP activity ratio and ultimately the degree of contractile force because MLCK activity depends on the amount of the Ca 2ϩ -calmodulin complex, which itself hinges on cytosolic Ca 2ϩ levels. In many cases, however, the sensitivity of force to Ca 2ϩ can be changed by physiological modulation of the Ca 2ϩ dependence of MLC 20 phosphorylation (3, 4) or by other mechanisms such as thin filament disinhibition (5, 6).The nucleotide cyclic GMP has emerged as a potent, physiological second messenger involved in both vasodilator action and failure of vasoconstrictor activity. The neighboring endothelium, endogenous circulating hormones, as well as clinically administered nitrovasodilators all function to widen the lumen of vessels by stimulating guanylyl cyclase in vascular smooth muscle to produce cGMP (7). To date, cGMP has been implicated in lowering intracellular Ca 2ϩ (8, 9) and in decreasing sensitivity of the contractile force to Ca 2ϩ (10,11). A myriad of Ca 2ϩ lowering mechanisms have since been reportedly shown (see Ref. 9 for references): increased Ca 2ϩ sequestration, increased Ca 2ϩ efflux, decreased Ca 2ϩ influx through decreased Ca 2ϩ channel activity and through hyperpolarization via increased K ϩ channel activity, and decreased Ca 2ϩ release through antagonism of ...

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The Chilean salmon industry has undergone a rapid development making the country the world’s second largest producer of farmed salmon, but this growth has been accompanied by an intensive use of antibiotics. This overuse has become so significant that Chilean salmon aquaculture currently has one of the highest rates of antibiotic consumption per ton of harvested fish in the world. This review has focused on discussing use of antibiotics and current status of scientific knowledge regarding to incidence of antimicrobial resistance and associated genes in the Chilean salmonid farms. Over recent years there has been a consistent increase in the amount of antimicrobials used by Chilean salmonid farms, from 143.2 tons in 2010 to 382.5 tons in 2016. During 2016, Chilean companies utilized approximately 0.53 kg of antibiotics per ton of harvested salmon, 363.4 tons (95%) were used in marine farms, and 19.1 tons (5%) in freshwater farms dedicated to smolt production. Florfenicol and oxytetracycline were by far the most frequently used antibiotics during 2016 (82.5 and 16.8%, respectively), mainly being used to treat Piscirickettsia salmonis, currently considered the main bacterial threat to this industry. However, the increasing development of this industry in Chile, as well as the intensive use of antimicrobials, has not been accompanied by the necessary scientific research needed to understand the impact of the intensive use of antibiotics in this industry. Over the last two decades several studies assessing antimicrobial resistance and the resistome in the freshwater and marine environment impacted by salmon farming have been conducted, but information on the ecological and environmental consequences of antibiotic use in fish farming is still scarce. In addition, studies reporting the antimicrobial susceptibility of bacterial pathogens, mainly P. salmonis, have been developed, but a high number of these studies were aimed at setting their epidemiological cut-off values. In conclusion, further studies are urgently required, mainly focused on understanding the evolution and epidemiology of resistance genes in Chilean salmonid farming, and to investigate the feasibility of a link between these genes among bacteria from salmonid farms and human and fish pathogens.

Mitogen-activated protein kinase p38 is a serine/threonine kinase originally isolated from lipopolysaccharide (LPS) stimulated monocytes. There are four isoforms p38alpha p38beta, p38gamma, and p38delta. The most thoroughly studied isoform is p38alpha, whose activation has been observed in many hematopoietic and non-hematopoietic cell types upon appropriate stimuli. Subsequently, p38alpha kinase has been shown to be involved in the biosynthesis of TNFalpha and IL-1beta at the translational and transcriptional level. MAP kinase p38alpha represents a point of convergence for multiple signaling processes that are activated in inflammation and thus a key potential target for the modulation of cytokine production. The discovery and publication of p38alpha and the pyridinyl-imidazole inhibitor initiated a huge effort by many companies to develop p38alpha inhibitors as potential treatment for inflammatory diseases. Herein we provide a brief overview of recent reported clinical results for AMG 548, BIRB 796, VX 702, SCIO 469, and SCIO 323. However, our focus will be on the binding modes of these inhibitors and other p38 inhibitors in the recent literature.

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