Bronchoconstrictor effect of thrombin and thrombin receptor activating peptide in guinea-pigs in vivo

1. Several thrombin cellular effects are dependent upon stimulation of proteinase activated receptor-1 (PAR-1) localized over the cellular surface. Following activation by thrombin, a new N-terminus peptide is unmasked on PAR-1 receptor, which functions as a tethered ligand for the receptor itself. Synthetic peptides called thrombin receptor activating peptides (TRAPs), corresponding to the N-terminus residue unmasked, reproduce several thrombin cellular effects, but are devoid of catalytic activity. We have evaluated the bronchial response to intravenous administration of human alpha-thrombin or a thrombin receptor activating peptide (TRAP-9) in anaesthetized, artificially ventilated guinea-pigs. 2. Intravenous injection of thrombin (100 microkg(-1)) caused bronchoconstriction that was recapitulated by injection of TRAP-9 (1 mg kg(-1)). Animal pretreatment with the thrombin inhibitor Hirulog (10 mg kg(-1) i.v.) prevented thrombin-induced bronchoconstriction, but did not affect bronchoconstriction induced by TRAP-9. Both agents did not induce bronchoconstriction when injected intravenously to rats. 3. The bronchoconstrictor effect of thrombin and TRAP-9 was subjected to tolerance; however, in animals desensitized to thrombin effect, TRAP-9 was still capable of inducing bronchoconstriction, but not vice versa. 4. Depleting animals of circulating platelets prevented bronchoconstriction induced by both thrombin and TRAP-9. 5. Bronchoconstriction was paralleled by a biphasic change in arterial blood pressure, characterized by a hypotensive phase followed by a hypertensive phase. Thrombin-induced hypotension was not subject to tolerance and was inhibited by Hirulog; conversely, hypertension was subject to tolerance and was not inhibited by Hirulog. Hypotension and hypertension induced by TRAP-9 were neither subject to tolerance nor inhibited by Hirulog. 6. Our results indicate that thrombin causes bronchoconstriction in guinea-pigs through a mechanism that requires proteolytic activation of its receptor and the exposure of the tethered ligand peptide. Platelet activation might be triggered by the thrombin effect.     

Pharmacological tools for hydrogen sulphide research: a brief,introductory guide for beginners

The purpose of this brief review is to help researchers in their initial approach to the H₂S field and to provide answers for the most frequently posed questions by newcomers to the topic related to H₂S donors and inhibitors of H₂S synthesis, as well as methods to measure H₂S production. Here the reader will find a practical guide that provides fast and to the point information on how to (i) deliver H₂S to cells; (ii) modulate its endogenous production; and (iii) measure its levels in fluids, cells and tissues in order to gain an understanding of its role in health and disease.

Linked Articles

This article is part of a themed section on Pharmacology of the Gasotransmitters. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-6     

Porphyromonas gingivalis HmuY‐Induced Production of Interleukin‐6 and IL‐6 Polymorphism in Chronic Periodontitis

Background: In chronic periodontitis (CP), the gene polymorphism of interleukin‐6 (IL‐6) to 174C/G has been associated with the altered production of this cytokine. The aim of this pilot study is to compare the allelic and genotypic frequencies in patients with CP with control individuals without periodontitis (NP) and to measure the production of IL‐6 by whole blood cells stimulated with Porphyromonas gingivalis HmuY protein. Methods: DNA was isolated from peripheral blood cells of 49 patients with CP and 60 control individuals classified as NP, and genotyping was performed by polymerase chain reaction using sequence‐specific primers. Whole blood cells from 29 patients with CP and 30 control individuals were stimulated for 48 hours with HmuY, and IL‐6 levels were measured using enzyme‐linked immunosorbent assay. Results: The proportion of individuals carrying the G allele at position –174 of the IL‐6 gene was higher in the group with CP (85.7%) than in the normal control group (73.3%; P <0.03). P. gingivalis HmuY‐induced production of IL‐6 was higher in the group with CP (P <0.05). Conclusions: Our findings suggest that P. gingivalis HmuY may be associated with increased IL‐6 production during CP. Furthermore, patients with periodontitis and individuals with higher HmuY‐induced production of IL‐6 show a high frequency of the G allele at position –174.     

Analysis of protease-activated receptor-1 and -2 in human scar formation

Protease-activated receptor (PAR)-1 and PAR-2 are reported to contribute to the fibrotic process in a number of organs, including lung, liver, pancreas, and kidney. The aim of this study was to localize expression and biological activity of PAR-1 and PAR-2 in normal and pathological cutaneous scars. First, we investigated the immunohistochemical expression of PAR-1 and PAR-2 proteins in a series of human normal scars (NS, n = 10), hypertrophic scars (HS, n = 10), and keloids (K, n = 10). Expression of PAR-1 and PAR-2 was observed in all types of scar. Specifically, in HS and K, diffuse PAR-1 and PAR-2 positivity was found in dermal cellular areas composed of myofibroblasts, while no or minor staining was observed in the scattered fibroblasts embedded in abundant extracellular matrix in the context of the more collagenous nodules, irrespective of the type of scar. The hyperplastic epidermis overlying K was also found to be strongly PAR-1 and PAR-2 positive, whilst in most NS and HS the epidermis was faintly to moderately stained. Second, ribonuclease protection assay on paraffin-embedded specimens showed overexpression of PAR-1 and PAR-2 mRNA in K compared to NS and HS. Third, cultured human fibroblasts exposed to TGF-beta1 expressed a myofibroblast phenotype associated with overexpression of PAR-2, while PAR-1 expression was unaffected. Intracellular Ca(2+) mobilization by PAR-2 agonists in myofibroblasts was increased as compared to fibroblasts, whereas the effect of PAR-1 agonists was unchanged. Our in vivo study indicates that PAR-1 and PAR-2 are expressed in cells involved in physiological and pathological scar formation and suggests that in vitro overexpression and exaggerated functional response of PAR-2 may play a role in the function of myofibroblasts in scar evolution from a physiological repair process to a pathological tissue response.     

Spatial distribution of specialized cardiac care units in the state of Santa Catarina

OBJECTIVE

To analyze the methodology used for assessing the spatial distribution of specialized cardiac care units.

METHODS

A modeling and simulation method was adopted for the practical application of cardiac care service in the state of Santa Catarina, Southern Brazil, using the p-median model. As the state is divided into 21 health care regions, a methodology which suggests an arrangement of eight intermediate cardiac care units was analyzed, comparing the results obtained using data from 1996 and 2012.

RESULTS

Results obtained using data from 2012 indicated significant changes in the state, particularly in relation to the increased population density in the coastal regions. The current study provided a satisfactory response, indicated by the homogeneity of the results regarding the location of the intermediate cardiac care units and their respective regional administrations, thereby decreasing the average distance traveled by users to health care units, located in higher population density areas. The validity of the model was corroborated through the analysis of the allocation of the median vertices proposed in 1996 and 2012.

CONCLUSIONS

The current spatial distribution of specialized cardiac care units is more homogeneous and reflects the demographic changes that have occurred in the state over the last 17 years. The comparison between the two simulations and the current configuration showed the validity of the proposed model as an aid in decision making for system expansion.     

Inhibition of hydrogen sulfide generation contributes to gastric injury caused by anti-inflammatory nonsteroidal drugs

BACKGROUND & AIMS: Hydrogen sulfide (H(2)S), an endogenous gaseous mediator that causes vasodilation, is generated in mammalian tissues by cystathionine beta-synthase (CBS) and cystathionine-gamma-lyase (CSE). Here, we have investigated the role of H(2)S in a rodent model of nonsteroidal anti-inflammatory drug (NSAID) gastropathy. METHODS: Rats were given acetyl salycilic acid (ASA) or an NSAID alone or in combination with NaHS, an H(2)S donor, and killed 3 hours later. Gastric blood flow was measured by laser-Doppler flowmetry, whereas intravital microscopy was used to quantify adhesion of leukocytes to mesenteric postcapillary endothelium. RESULTS: At a dose of 100 micromol/kg, NaHS attenuated by 60%-70% the gastric mucosal injury, and tumor necrosis factor (TNF)-alpha, intercellular adhesion molecule (ICAM)-1, and lymphocyte function-associated antigen (LFA)-1 mRNA up-regulation induced by NSAIDs (P < .05) NaHS administration prevented the associated reduction of gastric mucosal blood flow (P < .05) and reduced ASA-induced leukocyte adherence in mesenteric venules. NaHS did not affect suppression of prostaglandin E(2) (PGE(2)) synthesis by NSAIDs. Glibenclamide, a K(ATP) channel inhibitor, and DL-propargylglycine, a CSE inhibitor, exacerbated, whereas pinacidil, a K(ATP) opener, attenuated gastric injury caused by ASA. Exposure to NSAIDs reduced H(2)S formation and CSE expression (mRNA and protein) and activity by 60%-70%. By promoter deletion and mutation analysis, an Sp1 consensus site was identified in the CSE promoter. Exposure to NSAIDs inhibits Sp1 binding to its promoter and abrogates CSE expression in HEK-293 cells transfected with a vector containing the core CSE promoter. Exposure to NSAIDs inhibits Sp1 and ERK phosphorylation. CONCLUSIONS: These data establish a physiologic role for H(2)S in regulating the gastric microcirculation and identify CSE as a novel target for ASA/NSAIDs.     

Clinical epidemiological profile of vitiligo in children and adolescents

94 children and 25 adolescents, 42% male and 58% female, aged predominantly between six and ten years old (40%) were studied at the Martagão Gesteira Childcare and Pediatrics Institute (Rio de Janeiro Federal University) between 2005 and 2011. The prevalent clinical form of vitiligo was the generalized type (34%). Although the clinical response was similar between the treatment modalities, we decided for low and high power topical steroids in our routine. Halo nevi were found in seven (5.9%) cases. Thirty (25%) patients underwent specialized evaluation and 18 (60%) reported some relevant psychological situation.     

Peripheral relaxant activity of apomorphine and of a D1 selective receptor agonist on human corpus cavernosum strips

Apomorphine is used in the erectile dysfunction therapy and its action has been ascribed to the stimulation of central dopamine receptor. At the present stage, very little is known about the peripheral action of apomorphine on human corpus cavernosum (HCC). We have investigated the peripheral action of apomorphine and the role of dopamine receptors in HCC. We here demonstrate that both D1 and D2 receptors were expressed in the HCC, D1 receptors were two-fold more abundant than D2 and that both receptors were mainly localized on the smooth muscle cell component. Apomorphine in vitro exerted an anti-alpha1 adrenergic activity in human cavernosal strips since it prevented contraction induced by phenylephrine (PE), but not by U46619 or endothelin. Apomorphine elicited endothelium-independent and concentration-dependent relaxation of the strips contracted by PE, U46619 or endothelin. The EC50 values (microM) for apomorphine, in the presence and absence of endothelium, were 51.0+/-16 and 16.0+/-14, 120+/-19 and 150+/-18, 59.0+/-15 and 140+/-50 on PE-, U46619- or endothelin-induced contraction, respectively. Selective dopamine receptor agonist A-68930 (D1-like), but not quinpirole (D2-like), caused concentration-dependent relaxation of the cavernosal strips, which was partially prevented by endothelium removal or by treatment with an inhibitor of nitric oxide (NO) synthase. In conclusion, we show that (1) apomorphine has a peripheral relaxant direct effect as well as an antiadrenergic activity, (2) HCC possesses more D1-like (D1 and D5) than D2-like (D2, D3 and D4) receptors, (3) both D1- and D2-like receptors are mainly localized on smooth muscle cells and (4) the relaxant activity is most probably mediated by D1-like receptor partially through NO release from endothelium.     

Angiopoietin-2 causes inflammation in vivo by promoting vascular leakage

Angiopoietins (Angs) are endothelium-selective ligands that exert most of their actions through the Tie-2 receptor. It is widely accepted that Ang-1 promotes the structural integrity of blood vessels and exhibits anti-inflammatory properties. In contrast, the role of Ang-2 remains less clear because it has been shown to behave as a Tie-2 agonist or antagonist under different experimental conditions. To define the role of Ang-2 in acute inflammation, we studied the effects of recombinant Ang-2 administration in vivo. We show herein that Ang-2, but not Ang-1, induces edema formation in the mouse paw in a dose-dependent manner; the edema seems to be fast-peaking (maximum at 30 min) and resolves within 4 h. The effect of Ang-2 is blocked by the coadministration with a soluble form of the Tie-2 receptor or Ang-1. NO and prostaglandin E(2) levels in mouse paw following the injection of Ang-2 remained unaltered, suggesting that the action of Ang-2 does not involve these mediators. In addition, Ang-2 exerted a weak stimulatory effect on leukocyte migration in the mouse paw. Similarly, Ang-2 injected into the mouse air pouch produced only a modest effect on cell extravasation that peaked at 30 min. However, when cell migration was elicited using zymosan, Ang-2 significantly inhibited leukocyte migration. We conclude that Ang-2 by itself stimulates the extravasation of cell-poor fluid, but in the presence of ongoing inflammation it reduces cellular infiltration in tissues.