Endothelium-dependent vasodilation in human mesenteric artery is primarily mediated by myoendothelial gap junctions intermediate conductance calcium-activated K+ channel and nitric oxide

Myoendothelial microdomain signaling via localized calcium-activated potassium channel (K(Ca)) and gap junction connexins (Cx) is critical for endothelium-dependent vasodilation in rat mesenteric artery. The present study determines the relative contribution of NO and gap junction-K(Ca) mediated microdomain signaling to endothelium-dependent vasodilation in human mesenteric artery. The hypothesis tested was that such activity is due to NO and localized K(Ca) and Cx activity. In mesenteric arteries from intestinal surgery patients, endothelium-dependent vasodilation was characterized using pressure myography with pharmacological intervention. Vessel morphology was examined using immunohistochemical and ultrastructural techniques. In vessel segments at 80 mm Hg, the intermediate (I)K(Ca) blocker 1-[(2-chlorophenyl)diphenyl-methyl]-1H-pyrazole (TRAM-34; 1 μM) inhibited bradykinin (0.1 nM-3 μM)-induced vasodilation, whereas the small (S) K(Ca) blocker apamin (50 and 100 nM) had no effect. Direct IK(Ca) activation with 1-ethyl-2-benzimidazolinone (1-EBIO; 10-300 μM) induced vasodilation, whereas cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine (1-30 μM), the SK(Ca) activator, failed to dilate arteries, whereas dilation induced by 1-EBIO (10-100 μM) was blocked by TRAM-34. Bradykinin-mediated vasodilation was attenuated by putative gap junction block with carbenoxolone (100 μM), with remaining dilation blocked by N-nitro l-arginine methyl ester (100 μM) and [1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one] (10 μM), NO synthase and soluble guanylate cyclase blockers, respectively. In human mesenteric artery, myoendothelial gap junction and IK(Ca) activity are consistent with Cx37 and IK(Ca) microdomain expression and distribution. Data suggest that endothelium-dependent vasodilation is primarily mediated by NO, IK(Ca), and gap junction Cx37 in this vessel. Myoendothelial microdomain signaling sites are present in human mesenteric artery and are likely to contribute to endothelium-dependent vasodilation via a mechanism that is conserved between species.     

Optimizing primary PCI beyond “door to intervention time”—are we there yet?

AimTo assess the effects of shortened door-to-intervention (DTI) time on appropriate clinical decisions regarding the four most critical and costly decisions during primary percutaneous coronary intervention (PCI): cath-lab activation (CLA), use of glycoprotein IIb/IIIa inhibitors (GPI), use of PCI, and deployment of drug-eluting stent (DES).BackgroundSTEMI PCI patients are frequently subject to decision making based on abbreviated medical encounter and limited medical information.MethodsClinical data were prospectively collected in a STEMI registry over 19 months. Retrospective chart reviews were conducted to determine the level of appropriateness of the above-mentioned decisions.ResultsBetween June 2006 and December 2007, 200 EKGs with suspected STEMI were transmitted; 88 (44%) resulted in CLA. Compared to prior year, DTI times decreased from 145.7 to 69.9 min (P=.00001). DTI was longer during nights and weekends (87.5 vs. 51.8 min, P=.001) and the initial 6 months of the registry (86.8 vs. 66.8 min, P=.07). Nineteen (21.6%) of the patients undergoing angiography did not require revascularization, 56 (63.6%) received GPIs, and 65 patients (73.8%) underwent at least one vessel PCI, and at least one DES was used in 39 patients (60% of PCI cohort).When assessed for appropriateness, CLA was appropriate in 81.8% of the time and rendered borderline or inappropriate in 5.7% and 12.5%, respectively. GPI use was appropriate in 66% of the patients but seemed borderline or inappropriate in 28.5% and 5.4%, respectively. PCI was appropriate in 90% of the lesions treated, and borderline or inappropriate in 7.1% and 2.9%, respectively. DES use was viewed appropriate in 38.4%, and borderline or inappropriate in 51% and 10.2% of the DES deployments, respectively.Conclusions(1) In view of expedited care, certain information required for decision-making process is either not available or ignored during primary PCI. (2) Appropriate use of resources in primary PCI needs to be better defined. (3) Measures of extracting patients' previous medical records and imaging studies along with in-lab immediate blood work and echocardiography and establishing new “time-out” protocols for STEMI patients may improve resource utilization and patient care and outcome.     

Anatomic classification of the endoscopic appearance of the normal appendiceal orifice: a novel tool for recognition and documentation of cecal intubation

Complete colonoscopy for cancer screening requires cecal intubation. Failure to reach and examine the cecum may result in missed right colon pathology. We developed and validated a novel classification scheme for the endoscopic appearance of the normal appendiceal orifice (AO). We analyzed 1,456 AO images and grouped them into four categories based on distinguishing features: "diverticuloid," "umbilicoid," "crescent," and "linear." An expert panel classified the images and modified these categories, combining crescent and linear categories into "curvilinear." A 100-image subset was classified twice by a validation cohort consisting of gastroenterology faculty and fellows. Inter-observer agreement among the expert panel, and intra- and inter-observer agreement among the validation cohort were analyzed using Fleiss' kappa statistic. The distribution of AO images was 67% curvilinear, 19% umbilicoid, and 10% diverticuloid; 85 images (4%) were not classifiable. There was substantial inter-observer agreement among the expert panel (κ, 0.72). Inter-observer agreement among the validation cohort was moderate (κ, 0.53 and 0.55 for the first and second viewing, respectively). Intra-observer κ values among the validation cohort were 0.69 for the overall classification, 0.65 for diverticuloid, 0.70 for umbilicoid, and 0.70 for curvilinear, indicating substantial agreement. This simple, validated classification scheme for the endoscopic appearance of the normal AO can be used both as a research and clinical tool to measure endoscopic quality, improve cecal examination, and document successful cecal intubation.     

Cannabinoid receptor CB2 modulates the CXCL12/CXCR4-mediated chemotaxis of T lymphocytes

Cannabinoids have been shown to influence the immune system. However, their immunomodulatory effects have not been extensively studied. In this investigation, we have observed that both primary and Jurkat T cells express a functional cannabinoid receptor 2 (CB₂). Furthermore, both the synthetic cannabinoids CP55,940 and WIN55,212-2, as well as the CB₂-selective agonist JWH-015, caused a significant inhibition of the chemokine CXCL12-induced and CXCR4-mediated chemotaxis of Jurkat T cells, as well as their transendothelial migration. Involvement of the CB₂ receptor was further confirmed by partial reversal of the inhibition using the CB₂-specific antagonist, AM630. Similarly, CP55,940 and JWH-015 inhibited the CXCL12-induced chemotaxis of primary CD4⁺ and CD8⁺ T lymphocytes. Further investigation of signaling studies to delineate the mechanism of inhibition revealed that cannabinoids enhance CXCL12-induced p44/42 MAP kinase activity. However, enhanced MAP kinase activity was not responsible for the inhibition of chemotaxis. This suggests that cannabinoids differentially regulate CXCR4-mediated migration and MAP kinase activation in T cells. Cannabinoids were also found to downregulate the PMA-enhanced enzyme activity of matrix metalloproteinase-9, which is known to play an important role in transendothelial migration. This study provides novel information regarding cannabinoid modulation of functional effects in T cells.