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This paper describes the synthesis, solution-phase biophysical studies, and X-ray crystallographic structures of hexamers formed by macrocyclic β-hairpin peptides derived from the central and C-terminal regions of Aβ, which bear tails derived from the N-terminus of Aβ. Soluble oligomers of the β-amyloid peptide, Aβ, are thought to be the synaptotoxic species responsible for neurodegeneration in Alzheimers disease. Over the last 20 years, evidence has accumulated that implicates the N-terminus of Aβ as a region that may initiate the formation of damaging oligomeric species. We previously studied, in our laboratory, macrocyclic β-hairpin peptides derived from Aβ16-22 and Aβ30-36, capable of forming hexamers that can be observed by X-ray crystallography and SDS-PAGE. To better mimic oligomers of full length Aβ, we use an orthogonal protecting group strategy during the synthesis to append residues from Aβ1-14 to the parent macrocyclic β-hairpin peptide 1, which comprises Aβ16-22 and Aβ30-36. The N-terminally extended peptides N+1, N+2, N+4, N+6, N+8, N+10, N+12, and N+14 assemble to form dimers, trimers, and hexamers in solution-phase studies. X-ray crystallography reveals that peptide N+1 assembles to form a hexamer that is composed of dimers and trimers. These observations are consistent with a model in which the assembly of Aβ oligomers is driven by hydrogen bonding and hydrophobic packing of the residues from the central and C-terminal regions, with the N-terminus of Aβ accommodated by the oligomers as an unstructured tail.

Despite decades of effort aimed at developing clinically effective cell therapies, including mixed population mononuclear cells, to revascularize the ischemic limb, there remains a paucity of patient-based studies that inform the function and fate of candidate cell types. In this study, we showed that circulating proangiogenic/arteriogenic monocytes (PAMs) expressing the FcγIIIA receptor CD16 were elevated in patients with chronic limb-threatening ischemia (CLTI), and these amounts decreased after revascularization. Unlike CD16-negative monocytes, PAMs showed large vessel remodeling properties in vitro when cultured with endothelial cells and smooth muscle cells and promoted salvage of the ischemic limb in vivo in a mouse model of hindlimb ischemia. PAMs showed a propensity to migrate toward and bind to ischemic muscle and to secrete angiogenic/arteriogenic factors, vascular endothelial growth factor A (VEGF-A) and heparin-binding epidermal growth factor. We instigated a first-in-human single-arm cohort study in which autologous PAMs were injected into the ischemic limbs of five patients with CLTI. Greater than 25% of injected cells were retained in the leg for at least 72 hours, of which greater than 80% were viable, with evidence of enhanced large vessel remodeling in the injected muscle area. In summary, we identified up-regulation of a circulatory PAM subpopulation as an endogenous response to limb ischemia in CLTI and tested a potentially clinically relevant therapeutic strategy. Editor's summary: Peripheral vascular disease can cause chronic limb-threatening ischemia (CLTI), which decreases quality of life and can lead to amputation. Patel et al. found that a specific population of proangiogenic/arteriogenic monocytes (PAMs) are increased in circulation in response to CLTI. PAMs from patients with CLTI secreted growth factors that led to increased vascular cell proliferation in vitro. Markers of angiogenesis and arteriogenesis were increased in mice with hindlimb ischemia treated with PAMs from patients. PAMs adhered to ischemic human muscle more than other monocytes. In a clinical study, PAMs injected into human ischemic limb muscle were partially retained around the injection site for up to 72 hours. These results suggest that using patient-derived PAMs could be a therapeutic approach for treating CLTI. —Brandon Berry [ABSTRACT FROM AUTHOR]

Peripheral arterial stenoses (PAS) are commonly investigated with duplex ultrasound (DUS) and angiography, but these are not functional tests. Fractional flow reserve (FFR), a pressure based index, functionally assesses the ischaemic potential of coronary stenoses, but its utility in PAS is unknown. FFR in the peripheral vasculature in patients with limb ischaemia was investigated. Patients scheduled for angioplasty and or stenting of isolated iliac and superficial femoral artery stenoses were recruited. Resting trans-lesional pressure gradient (P d / P a) and FFR were measured after adenosine provoked hyperaemia using an intra-arterial 0.014 inch flow and pressure sensing wire (ComboWire XT, Philips). Prior to revascularisation, exercise ABPI (eABPI) and DUS derived peak systolic velocity ratio (PSVR) of the index lesion were determined. Calf muscle oxygenation was measured using blood oxygenation level dependent cardiovascular magnetic resonance prior to and after revascularisation. Forty-one patients (32, 78%, male, mean age 65 ± 11 years) with 61 stenoses (iliac 32; femoral 29) were studied. For lesions < 80% stenosis, resting P d / P a was not influenced by the degree of stenosis (p =.074); however, FFR was discriminatory, decreasing as the severity of stenosis increased (p =.019). An FFR of < 0.60 was associated with critical limb threatening ischaemia (area under the curve [AUC] 0.87; 95% CI 0.75 – 0.95), in this study performing better than angiographic % stenosis (0.79; 0.63 – 0.89), eABPI (0.72; 0.57 – 0.83), and PSVR (0.65; 0.51 – 0.78). FFR correlated strongly with calf oxygenation (rho, 0.76; p <.001). A greater increase in FFR signalled resolution of symptoms and signs (ΔFFR 0.25 ± 0.15 vs. 0.13 ± 0.09; p =.009) and a post-angioplasty and stenting FFR of > 0.74 predicted successful revascularisation (combined sensitivity and specificity of 95%; AUC 0.98; 0.91 – 1.00). This pilot study demonstrates that FFR can objectively measure the functional significance of PAS that compares favourably with visual and DUS based assessments. Its role as a quality control adjunct that confirms optimal vessel patency after angioplasty and or stenting also merits further investigation. [ABSTRACT FROM AUTHOR]

Inferior vena cava (IVC) stenting may provide benefit to patients with symptomatic obstruction; however, there are no devices currently licensed for use in the IVC and systematic reviews on the topic are lacking. The aim of this study was to carry out a systematic review of the literature and meta-analysis to investigate the safety and efficacy of IVC stenting in all adult patient groups. The Medline and Embase databases were searched for studies reporting outcomes for safety and effectiveness of IVC stenting for any indication in series of 10 or more patients. A systematic review of the literature was carried out according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Thirty-three studies were included describing 1 575 patients. Indications for stenting were malignant IVC syndrome (229 patients), thrombotic disease (807 patients), Budd–Chiari syndrome (501 patients), and IVC stenosis post liver transplantation (47 patients). The male:female ratio was 2:1 and the median age ranged from 30 to 61 years. The studies included were not suitable for formal meta-analysis as 30/33 were single centre retrospective studies with no control groups and there was considerable inconsistency in outcome reporting. There was significant risk of bias in 94% of studies. Median reported technical success was 100% (range 78 – 100%), primary patency was 75% (38 – 98%), and secondary patency was 91.5% (77 – 100%). Major complications were pulmonary embolism (three cases), stent migration (12 cases), and major bleeding (15 cases), and there were three deaths in the immediate post-operative period. Most studies reported improvement in clinical symptoms but formal reporting tools were not used consistently. The evidence base for IVC stenting consists of predominantly single centre, retrospective, observational studies that have a high risk of bias. Nonetheless the procedure appears safe with few major adverse events, and studies that reported clinical outcomes demonstrate improvement in symptoms and quality of life. Randomised controlled trials and prospective registry based studies with larger patient numbers and standardised outcome are required to improve the evidence base for this procedure. [ABSTRACT FROM AUTHOR]

Chronic venous disease and venous hypertension are common consequences of valve insufficiency, yet the molecular mechanisms regulating the formation and maintenance of venous valves have not been studied. Here, we provide what we believe to be the first description of venous valve morphogenesis and identify signaling pathways required for the process. The initial stages of valve development were found to involve induction of ephrin-B2, a key marker of arterial identity, by venous endothelial cells. Intriguingly, developing and mature venous valves also expressed a repertoire of proteins, including prospero-related homeobox 1 (Prox1), Vegfr3, and integrin-α9, previously characterized as specific and critical regulators of lymphangiogenesis. Using global and venous valve-selective knockout mice, we further demonstrate the requirement of ephrin-B2 and integrin-α9 signaling for the development and maintenance of venous valves. Our findings therefore identified molecular regulators of venous valve development and maintenance and highlighted the involvement of common morphogenetic processes and signaling pathways in controlling valve formation in veins and lymphatic vessels. Unexpectedly, we found that venous valve endothelial cells closely resemble lymphatic (valve) endothelia at the molecular level, suggesting plasticity in the ability of a terminally differentiated endothelial cell to take on a different phenotypic identity., Introduction Luminal valves are required in the heart, veins, and lymphatic vessels to ensure unidirectional flow of blood and lymph. In addition, specialized intraluminal valves at the connections of the [...]

Atherosclerosis and its consequences remain the main cause of mortality in industrialized and developing nations. Plaque burden and progression have been shown to be independent predictors for future cardiac events by intravascular ultrasound. Routine prospective imaging is hampered by the invasive nature of intravascular ultrasound. A noninvasive technique would therefore be more suitable for screening of atherosclerosis in large populations. Here we introduce an elastin-specific magnetic resonance contrast agent (ESMA) for noninvasive quantification of plaque burden in a mouse model of atherosclerosis. The strong signal provided by ESMA allows for imaging with high spatial resolution, resulting in accurate assessment of plaque burden. Additionally, plaque characterization by quantifying intraplaque elastin content using signal intensity measurements is possible. Changes in elastin content and the high abundance of elastin during plaque development, in combination with the imaging properties of ESMA, provide potential for noninvasive assessment of plaque burden by molecular magnetic resonance imaging (MRI)., Cardiovascular imaging has been used for several decades to investigate vessel wall changes associated with atherosclerosis. Assessment of plaque burden, progression of disease and the evaluation of response to therapies [...]