Endothelium‐dependent and endothelium‐independent effects of 1‐nitro‐2‐propylbenzene on rat aorta

A group of nitro compounds contains a benzene ring in a short aliphatic chain with the NO₂ group, property that supposedly favors its vasodilator profile. In this study, we evaluated in isolated rat aorta the effects of 1‐nitro‐2‐propylbenzene (NPB), a nitro compound containing the NO₂ in the aromatic ring. In aorta precontracted with KCl, NPB (1‐3000 μm ) induced full endothelium‐independent relaxation. In endothelium‐intact preparations, phenylephrine‐induced contractions were fully relaxed by NPB, effect unaltered by N(ω)‐nitro‐L‐arginine methyl ester (L‐NAME) or 1H‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ). In the concentration range of 30–300 μm , NPB slightly but significantly potentiated the phenylephrine‐induced contraction. Such potentiation was unaltered by the thromboxane‐prostanoid receptor antagonist seratrodast, but was abolished by endothelium removal or by preincubation of endothelium‐intact preparations with L‐NAME, ODQ or by ruthenium red and HC‐030031, blockers of subtype 1 of ankyrin transient receptor potential (TRPA₁) channels. Verapamil exacerbated the potentiating effect of NPB. The potentiating effect was undetectable in preparations precontracted by 9,11‐dideoxy‐11α,9α‐epoxymethanoprostaglandin F2α (U‐46619). Relaxation was reduced by ruthenium red while it was enhanced by HC‐030031. In conclusion, NPB has vasodilator properties but with a mechanism of action distinct from its analogues. Contrary to other nitro compounds, its relaxing effects did not involve recruitment of the guanylyl cyclase pathway. NPB has also endothelium‐dependent potentiating properties on phenylephrine‐induced contractions, a phenomenon that putatively required a role of endothelial TRPA₁ channels. The present findings reinforce the notion that the functional group NO₂ in the aliphatic chain of these nitro compounds determines favorably their vasodilator properties.     

Spray‐ and laser‐assisted biomaterial processing for fast and efficient autologous cell‐plus‐matrix tissue engineering

At present, intensive investigation aims at the creation of optimal valvular prostheses. We introduced and tested the applicability and functionality of two advanced cell‐plus‐matrix seeding technologies, spray‐assisted bioprocessing (SaBP) and laser‐assisted bioprocessing (LaBP), for autologous tissue engineering (TE) of bioresorbable artificial grafts. For SaBP, human mesenchymal stem cells (HMSCs), umbilical cord vein endothelial cells (HUVECs) and fibrin were simultaneously spray‐administered on poly(ε‐caprolactone) (PCL) substrates. For LaBP, HUVECs and HMSCs were separately laser‐printed in stripes, followed by fibrin sealing. Three‐leaflet valves were manufactured following TE of electrospun PCL tissue equivalents. Grafts were monitored in vitro under static and dynamic conditions in bioreactors. SaBP and LaBP resulted in TE of grafts with homogeneous cell distribution and accurate cell pattern, respectively. The engineered valves demonstrated immediate sufficient performance, complete cell coating, proliferation, engraftment, HUVEC‐mediated invasion, HMSC differentiation and extracellular matrix deposition. SaBP revealed higher efficiency, with at least 12‐fold shorter processing time than the applied LaBP set‐up. LaBP realized coating with higher cell density and minimal cell–scaffold distance. Fibrin and PCL stability remain issues for improvement. The introduced TE technologies resulted in complete valvular cell‐plus‐matrix coating, excellent engraftment and HMSCs differentiation. SaBP might have potential for intraoperative table‐side TE considering the procedural duration and ease of implementation. LaBP might accelerate engraftment with precise patterns. Copyright © 2012 John Wiley & Sons, Ltd.     

Precision and accuracy of point‐of‐care testing coagulometers used for self‐testing and self‐management of oral anticoagulation therapy

Summary. Background: Oral anticoagulation therapy is monitored by the use of the International Normalized Ratio (INR). Patients who perform self‐testing or self‐management use a point‐of‐care testing (POCT) coagulometer (INR monitor) to estimate their INRs. A precondition for a correct dosage of coumarins is a correct INR estimation, and the method and apparatus used for providing the INR measurements are crucial in this context. Several studies have been published regarding the precision and accuracy of these POCT coagulometers, and have led to diverse conclusions. It is difficult and challenging to perform an overview of the literature, owing to the vast amount of papers, with differences in design, statistical analysis, etc. Objectives: The aim of this systematic review was to analyze the current literature, especially regarding the precision and accuracy of the POCT coagulometers, to provide recommendations for clinical use and quality control, and to point out areas for future research. Methods: We included a total of 22 studies, of which four were characterized as high‐quality studies. Results: The precision of the POCT coagulometers was generally adequate for clinical use. Their performance in terms of accuracy has to be viewed in the context of the inherent inaccuracies of INR measurements. Conclusions: The accuracy of POCT coagulometers seems, in this respect, to be generally acceptable, and they can be used in a clinical setting.     

Two‐ and three‐dimensional prenatal sonographic diagnosis of prune‐belly syndrome

We report the prenatal diagnosis of 6 cases of Prune‐belly syndrome in the 2^nd trimester. The sonographic diagnosis was based on the findings of oligohydramnios, renal anomalies, and a lower abdominal cystic mass representing the abnormal dilatation of the bladder on conventional 2‐dimensional sonographic examination. We discuss the role of Doppler imaging and 3‐dimensional sonography as complementary methods to conventional sonography. Four of our 6 cases were confirmed with associated defects. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2010     

Activation of PAR‐2 Elicits NO‐Dependent and CGRP‐Independent Dilation of the Dural Artery

(Headache 2010;50:1017‐1030) Objectives.— The goal of this study was to determine the vascular effects of protease‐activated receptor‐2 (PAR‐2) activation in the rat cranial vasculature. Background.— The role of PAR‐2 in pain and inflammatory conditions has been established but the information available on its effects and receptor distribution in the trigeminal vascular axis is limited. We studied the dilatory function and expression of PAR‐2 in the neuro‐vascular circuit, critical in migraine pathogenesis. We also investigated the interaction of PAR‐2 with calcitonin gene‐related peptide (CGRP) and dural mast cells. Methods.— We used an improved model of intravital microscopy on the closed cranial window in rats to study the vascular effects of PAR‐2 activating peptides (PAR‐2 APs; SLIGRL‐NH₂, 2‐Furoyl‐LIGRLO‐NH₂) in the dural vasculature. Measurement of immunoreactive CGRP in skull halves and in trigeminal nucleus caudalis was done by using an enzyme‐linked immunosorbent assay. We also analyzed the presence of PAR‐2 in different migraine relevant tissues by quantitative real‐time PCR and Western blot analysis. Results.— PAR‐2 APs and trypsin induced a dose‐dependent increase in dural artery diameter. The topical application of a nonspecific nitric oxide synthase (NOS) inhibitor, L‐N^G‐Nitroarginine methyl ester, attenuated SLIGRL‐NH₂ responses. Olcegepant, a CGRP receptor antagonist, did not a have significant effect on the SLIGRL‐NH₂ responses, though exogenous CGRP responses were completely blocked. There was no significant release of CGRP from skull halves incubated with SLIGRL‐NH₂ as compared with those incubated with the corresponding negative peptide. Chronic mast cell degranulation did not change the vascular effects of PAR‐2 APs. mRNA and protein expression of PAR‐2 were found throughout trigeminovasuclar axis. Conclusion.— PAR‐2 activation leads to vasodilation of dural arteries and these responses are partially mediated by nitric oxide. As PAR‐2 is present throughout trigeminovasuclar axis, it may have a role in migraine pathogenesis, independent of CGRP and mast cell mediated mechanism.     

18F‐Fluorine‐18‐l‐dihydroxyphenylalanine (18F‐DOPA) positive isolated peritoneal carcinomatosis from a MENII‐related medullary thyroid carcinoma. About an atypical metastatic site and utility of 18F‐FDOPA

A patient, operated for a medullary thyroid carcinoma (MTC) with a positive RET mutation, showed several peritoneal nodes on a computed tomography (CT), with increased Thyrocalcitonine. A ¹⁸F‐Fluorine‐18‐l ‐dihydroxyphenylalanine (18‐F‐FDOPA) positron emission tomography (PET/CT) showed isolated tracer uptake on the nodes. A biopsy confirmed that it was from the MTC, with the same RET mutation as in blood.     

Aging and hypertension decrease endothelial NO‐related dilating function and gamma‐glutamyl transferase activity but not S‐nitrosoglutathione‐induced aortic vasodilation

S‐nitrosoglutathione (GSNO), which is involved in the transport and the storage of NO, induces vasorelaxation. It requires gamma‐glutamyl transferase (GGT), an enzyme present on the endothelium, to transfer NO into the cell. We evaluated whether aging and hypertension, which induce NO‐related dilating dysfunction, are associated with decreased vascular GGT activity and modify the vasorelaxant effect of GSNO. Thoracic aortic rings isolated from male spontaneous hypertensive rats (SHR) and Wistar‐Kyoto rats (WKY) aged 20–22 (adult) or 57–60 weeks (mature) were preconstricted with phenylephrine, then submitted to concentration‐vasorelaxant response curves (maximal response: E_max; pD₂) to GSNO and carbachol (the latter to measure NO‐related dilating function). GGT activity was measured using chromogenic substrate. Both aging and hypertension lowered E_max values for carbachol (E_max ?8% in adult SHR, ?42% in mature SHR vs. age‐matched WKY, p_age and p_hypertension < 0.05) demonstrating NO‐related dilating dysfunction. Aortic GGT activity also decreased with aging and hypertension (?22% in adult and ?75%, reaching 3 nmol/min/g of tissue, in mature SHR vs. 12 in age‐matched WKY and 23 in adult WKY, p_age and p_hypertension < 0.05). The pD₂ values of GSNO were similar in mature SHR and WKY but higher in adult SHR (p_interaction < 0.05). Aging in hypertensive rats decreased NO‐related vasorelaxant function and vascular GGT activity, but did not lower the vasorelaxant response to GSNO. This opens perspectives for GSNO‐based therapeutics restoring nitric oxide bioavailability and vascular protection in a context of endothelial dysfunction.     

High‐density lipoprotein from end‐stage renal disease patients exhibits superior cardioprotection and increase in sphingosine‐1‐phosphate

Background

Chronic kidney disease (CKD) exacerbates the risk of death due to cardiovascular disease (CVD). Modifications to blood lipid metabolism which manifest as increases in circulating triglycerides and reductions in high‐density lipoprotein (HDL) cholesterol are thought to contribute to increased risk. In CKD patients, higher HDL cholesterol levels were not associated with reduced mortality risk. Recent research has revealed numerous mechanisms by which HDL could favourably influence CVD risk. In this study, we compared plasma levels of sphingosine‐1‐phosphate (S1P), HDL‐associated S1P (HDL‐S1P) and HDL‐mediated protection against oxidative stress between CKD and control patients.

Methods

High‐density lipoprotein was individually isolated from 20 CKD patients and 20 controls. Plasma S1P, apolipoprotein M (apoM) concentrations, HDL‐S1P content and the capacity of HDL to protect cardiomyocytes against doxorubicin‐induced oxidative stress in vitro were measured.

Results

Chronic kidney disease patients showed a typical profile with significant reductions in plasma HDL cholesterol and albumin and an increase in triglycerides and pro‐inflammatory cytokines (TNF‐alpha and IL‐6). Unexpectedly, HDL‐S1P content (P = .001) and HDL cardioprotective capacity (P = .034) were increased significantly in CKD patients. Linear regression analysis of which factors could influence HDL‐S1P content showed an independent, negative and positive association with plasma albumin and apoM levels, respectively.

Discussion

The novel and unexpected observation in this study is that uremic HDL is more effective than control HDL for protecting cardiomyocytes against oxidative stress. It is explained by its higher S1P content which we previously demonstrated to be the determinant of HDL‐mediated cardioprotective capacity. Interestingly, lower concentrations of albumin in CKD are associated with higher HDL‐S1P.