Evaluating patient perspectives of endovascular created arteriovenous fistulas for dialysis access (EndoAVF).

BACKGROUND: Patient reported experience measures are contemporary quality indicators that focus on evaluation of healthcare delivery processes. While surgical arteriovenous fistulas (otherAVF) are preferred for haemodialysis vascular access, fears about surgery and complications often result in refusal/delays. A new technique of endovascular arteriovenous fistula creation (EndoAVF) has been developed and as part of it's ongoing introduction into our unit, the patient perspective was felt critical to its evaluation. The Vascular Access Questionnaire (VAQ) provides a mechanism for identifying and scoring perceptions in this setting. METHOD: Patients who had previously undergone EndoAVF formation were approached to undertake the VAQ as part of a service evaluation of their experience. In addition to the components of the VAQ, data questions relating to the patient's perception of their access were gathered. Results were compared with a matched historical cohort of surgically created fistulas (otherAVF) patients. RESULTS: Patient satisfaction and self-reported ease of use with EndoAVF were high. Overall VAQ scores were similar between the EndoAVF and the surgically created cohort. Functionally, there was no significant difference in perception of their fistula by patients, irrespective of them being created surgically or radiologically. CONCLUSION: Although numbers in this report are small limiting exploration of preserved inherent heterogeneity, we provide a useful initial patient reported experience and perspectives on comparative functional use of radiologically and surgically created AVFs. As real world experience gathers, future larger cohorts with adequate sampling may allow exploration of patient reported experiences and outcome measures.

A Review on the Hemodialysis Reliable Outflow (HeRO) Graft for Haemodialysis Vascular Access.

OBJECTIVES: With improved dialysis survival there are increasing numbers of patients who have exhausted definitive access options due to central venous stenosis and are maintaining dialysis on a central venous catheter. The Hemodialysis Reliable Outflow (HeRO) allows an alternative by providing a definitive access solution. The aim of this study is to systematically review the published outcomes of the HeRO graft and discuss the role in complex haemodialysis patients. METHODS: Electronic databases were searched for studies assessing the use of the HeRO graft for dialysis in accordance with PRISMA published up to December 31 2014. The primary outcomes for this study were 1-year primary and secondary patency rates. Secondary outcomes were rates of dialysis access associated steal syndrome, HeRO-related bacteraemia rates and rates of interventions. RESULTS: Following strict inclusion/exclusion criteria, eight studies including 409 patients were included in our review. Primary and secondary pooled patency rates in this complex cohort of dialysis patients were found to be 21.9% (9.6-37.2%) and 59.4% (39.4-78%). The rate of dialysis access associated steal syndrome was low at 6.3% (1-14.7%) as was the range of HeRO-related bacteraemia (0.13-0.7 events per 1000 days). CONCLUSIONS: This literature review shows that the HeRO graft is an acceptable option for complex dialysis patients who are catheter dependent. Owing to device availability, published data are predominantly North American and further longer-term studies in other populations may be necessary. In this challenging patient group, randomized controlled trials are required to allow comparisons with alternative access options.

Emergency treatment of haemorrhaging coeliac or mesenteric artery aneurysms and pseudoaneurysms in the era of endovascular management.

OBJECTIVES: Patients requiring emergency treatment of visceral artery aneurysms (VAAs) can be treated by endovascular or surgical techniques. Outcomes after failed attempts at endovascular control are unclear as is the present role of surgery. This study reviewed treatment and outcomes of a contemporary cohort of patients with symptomatic VAAs at a tertiary referral centre. METHODS: Patients undergoing emergency treatment of a VAA of the coeliac, mesenteric arteries, or their branches were identified over a 5-year period. Patient variables, treatments, and outcomes were assessed. RESULTS: Forty-eight patients underwent 65 radiological and two surgical procedures. Pseuodaneuryms were present in 45 (94%) of patients. Interventional radiology procedures were the initial treatment in every patient. The initial success was 40 out of 48 (83%). Patients requiring more than one procedure were all successfully treated. Regarding initial failures, if the VAA sac could not be accessed at angiography an alternative procedure to control the VAA was required in every case. If initial endovascular treatment failed, repeating the same procedure was successful in half of the patients. Ultrasound-guided percutaneous VAA embolisation was used in four patients. The 30-day mortality was eight out of 48 (17%). There were four recorded complications including one death directly attributable to VAA treatment. CONCLUSIONS: Patients needing emergency treatment of a VAA could be well served by non-surgical management. When the initial attempt at control of bleeding is unsuccessful it is important to consider non-conventional means of accessing these arteries. The need for surgery, in selected centres, may exist for a small group of patients after initial failed radiological treatment only.

Central venous obstruction in the thorax.

Central venous stenosis and occlusion can occur secondary to a spectrum of conditions ranging from aggressive malignancy to benign extrinsic anatomical compression in otherwise healthy individuals. Irrespective of aetiology, significant morbidity in the acute setting and long term can occur unless prompt accurate diagnosis and appropriate management is initiated, the radiologist being central to both. The present review will provide radiologists with a thorough illustration and explanation of the range of central venous conditions in the thorax (including deep vein thrombosis, thoracic outlet syndrome, haemodialysis, and malignancy related causes), the salient imaging findings and interventional management using case examples from the authors' practice.

The TGF-ß-Smad3 pathway inhibits CD28-dependent cell growth and proliferation of CD4 T cells.

Transforming growth factor-ß (TGF-ß) maintains self-tolerance through a constitutive inhibitory effect on T-cell reactivity. In most physiological situations, the tolerogenic effects of TGF-ß depend on the canonical signaling molecule Smad3. To characterize how TGF-ß/Smad3 signaling contributes to maintenance of T-cell tolerance, we characterized the transcriptional landscape downstream of TGF-ß/Smad3 signaling in resting or activated CD4 T cells. We report that in the presence of TGF-ß, Smad3 modulates the expression of >400 transcripts. Notably, we identified 40 transcripts whose expression showed Smad3 dependence in both resting and activated cells. This 'signature' confirmed the non-redundant role of Smad3 in TGF-ß biology and identified both known and putative immunoregulatory genes. Moreover, we provide genomic and functional evidence that the TGF-ß/Smad3 pathway regulates T-cell activation and metabolism. In particular, we show that TGF-ß/Smad3 signaling dampens the effect of CD28 stimulation on T-cell growth and proliferation. The impact of TGF-ß/Smad3 signals on T-cell activation was similar to that of the mTOR inhibitor Rapamycin. Considering the importance of co-stimulation on the outcome of T-cell activation, we propose that TGF-ß-Smad3 signaling may maintain T-cell tolerance by suppressing co-stimulation-dependent mobilization of anabolic pathways.

Inferior vena cava filters: what radiologists need to know.

Inferior vena cava (IVC) filters are a controversial mechanical adjunct in the prevention of pulmonary embolism, the most serious result of venous thromboembolism. Despite modern IVC filters being in clinical use for more than 45 years, there is still uncertainty amongst many radiologists about the indications for IVC filter placement and their removal, particularly the more recent prophylactic use in patients without confirmed deep vein thrombosis (DVT) or pulmonary embolism (PE). Recently published guidelines on filter use from the National Institute of Health and Clinical Excellence (NICE) and other professional bodies are discussed. The vast majority of IVC filters in the UK are inserted by interventional radiologists, so radiologists may be the first point of contact for information requested by other clinicians. The increasing use of filters means that radiologists will encounter filters increasingly often during abdominal cross-sectional imaging. Awareness of common filter-related complications, such as tilting, thrombosis, and caval perforation, is useful to reassure or alert other clinicians. The potential role of filters in upper extremity DVT and requirement for concomitant anticoagulation is discussed.

Congenital anomalies of the inferior vena cava.

Congenital anomalies of the inferior vena cava (IVC) and its tributaries are increasingly recognized in asymptomatic patients due to the more frequent use of cross-sectional imaging and computed tomography (CT) in particular. IVC development is a complex process involving formation of anastomoses between three pairs of embryonic veins in the 4th to 8th week of gestation. Various permutations occur in the basic venous plan of the abdomen and pelvis resulting in variants such as isolated left IVC, double IVC, and retroaortic left renal vein. The majority of these anomalies are asymptomatic but occasionally present clinically with thromboembolic complications. However, awareness of their existence is important to avoid important diagnostic pitfalls and in preoperative surgical and interventional radiological planning.

The vapour of imidazolium-based ionic liquids: a mass spectrometry study.

Eight common dialkylimidazolium-based ionic liquids have been successfully evaporated in ultra-high vacuum and their vapours analysed by line of sight mass spectrometry using electron ionisation. The ionic liquids investigated were 1-alkyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide, [C(n)C(1)Im][Tf(2)N] (where n = 2, 4, 6, 8), 1-alkyl-3-methylimidazolium tetrafluoroborate, [C(n)C(1)Im][BF(4)] (where n = 4, 8), 1-butyl-3-methylimidazolium octylsulfate, [C(4)C(1)Im][C(8)OSO(3)] and 1-butyl-3-methylimidazolium tetrachloroferrate, [C(4)C(1)Im][FeCl(4)]. All ionic liquids studied here evaporated as neutral ion pairs; no evidence of decomposition products in the vapour phase were observed. Key fragment cations of the ionised vapour of the ionic liquids are identified. The appearance energies, E(app), of the parent cation were measured and used to estimate the ionisation energies, E(i), for the vapour phase neutral ion pairs. Measured ionisation energies ranged from 10.5 eV to 13.0 eV. Using both the identity and E(app) values, the fragmentation pathways for a number of fragment cations are postulated. It will be shown that the enthalpy of vaporisation, Δ(vap)H, can successfully be measured using more than one fragment cation, although caution is required as many fragment cations can also be formed by ionisation of decomposition products.

Imaging and management of vascular malformations.

Vascular malformations are a diffuse collection of abnormalities that are usually present at birth but may present any time during childhood or as an adult. Historically terminology has been complicated and used interchangeably causing confusion to patients and clinicians alike; however, a structured internationally agreed classification system exists. It is not uncommon for patients with vascular malformations to be referred to various specialties without obtaining a correct diagnosis and appropriate treatment. Vascular malformations can occur anywhere within the body and all patients will require imaging at some stage; therefore, it is important for all radiologists to be aware of the correct terminology and imaging characteristics. This review discusses classification and illustrates salient imaging findings and the modern approach to treatment of vascular malformations.

Protein kinase B regulates T lymphocyte survival, nuclear factor kappaB activation, and Bcl-X(L) levels in vivo.

The serine/threonine kinase protein kinase B (PKB)/Akt mediates cell survival in a variety of systems. We have generated transgenic mice expressing a constitutively active form of PKB (gag-PKB) to examine the effects of PKB activity on T lymphocyte survival. Thymocytes and mature T cells overexpressing gag-PKB displayed increased active PKB, enhanced viability in culture, and resistance to a variety of apoptotic stimuli. PKB activity prolonged the survival of CD4(+)CD8(+) double positive (DP) thymocytes in fetal thymic organ culture, but was unable to prevent antigen-induced clonal deletion of thymocytes expressing the major histocompatibility complex class I-restricted P14 T cell receptor (TCR). In mature T lymphocytes, PKB can be activated in response to TCR stimulation, and peptide-antigen-specific proliferation is enhanced in T cells expressing the gag-PKB transgene. Both thymocytes and T cells overexpressing gag-PKB displayed elevated levels of the antiapoptotic molecule Bcl-X(L). In addition, the activation of peripheral T cells led to enhanced nuclear factor (NF)-kappaB activation via accelerated degradation of the NF-kappaB inhibitory protein IkappaBalpha. Our data highlight a physiological role for PKB in promoting survival of DP thymocytes and mature T cells, and provide evidence for the direct association of three major survival molecules (PKB, Bcl-X(L), and NF-kappaB) in vivo in T lymphocytes.

Negative regulation of T cell proliferation and interleukin 2 production by the serine threonine kinase GSK-3.

Glycogen synthase kinase (GSK)-3 is a protein serine/threonine kinase that regulates differentiation and cell fate in a variety of organisms. This study examined the role of GSK-3 in antigen-specific T cell responses. Using resting T cells from P14 T cell receptor (TCR)-transgenic mice (specific for the lymphocytic choriomeningitis virus and H-2D(b)), we demonstrated that GSK-3beta was inactivated by serine phosphorylation after viral peptide-specific stimulation in vitro. To further investigate the role of GSK-3, we have generated a retroviral vector that expresses a constitutively active form of GSK-3beta that has an alanine substitution at the regulatory amino acid, serine 9 (GSK-3betaA9). Retroviral transduction of P14 TCR-transgenic bone marrow stem cells, followed by reconstitution, led to the expression of GSK-3betaA9 in bone marrow chimeric mice. T cells from chimeric mice demonstrate a reduction in proliferation and interleukin (IL)-2 production. In contrast, in vitro assays done in the presence of the GSK-3 inhibitor lithium led to dramatically prolonged T cell proliferation and increased IL-2 production. Furthermore, in the presence of lithium, we show that nuclear factor of activated T cells (NF-AT)c remains in the nucleus after antigen-specific stimulation of T cells. Together, these data demonstrate that GSK-3 negatively regulates the duration of T cell responses.

X-ray crystal structure of C3d: a C3 fragment and ligand for complement receptor 2.

Activation and covalent attachment of complement component C3 to pathogens is the key step in complement-mediated host defense. Additionally, the antigen-bound C3d fragment interacts with complement receptor 2 (CR2; also known as CD21) on B cells and thereby contributes to the initiation of an acquired humoral response. The x-ray crystal structure of human C3d solved at 2.0 angstroms resolution reveals an alpha-alpha barrel with the residues responsible for thioester formation and covalent attachment at one end and an acidic pocket at the other. The structure supports a model whereby the transition of native C3 to its functionally active state involves the disruption of a complementary domain interface and provides insight into the basis for the interaction between C3d and CR2.

Function of PI3Kgamma in thymocyte development, T cell activation, and neutrophil migration.

Phosphoinositide 3-kinases (PI3Ks) regulate fundamental cellular responses such as proliferation, apoptosis, cell motility, and adhesion. Viable gene-targeted mice lacking the p110 catalytic subunit of PI3Kgamma were generated. We show that PI3Kgamma controls thymocyte survival and activation of mature T cells but has no role in the development or function of B cells. PI3Kgamma-deficient neutrophils exhibited severe defects in migration and respiratory burst in response to heterotrimeric GTP-binding protein (G protein)-coupled receptor (GPCR) agonists and chemotactic agents. PI3Kgamma links GPCR stimulation to the formation of phosphatidylinositol 3,4,5-triphosphate and the activation of protein kinase B, ribosomal protein S6 kinase, and extracellular signal-regulated kinases 1 and 2. Thus, PI3Kgamma regulates thymocyte development, T cell activation, neutrophil migration, and the oxidative burst.

Measurement of botulinum types A, B and E neurotoxicity using the phrenic nerve-hemidiaphragm: improved precision with in-bred mice.

Botulinum neurotoxins induce a prolonged muscle paralysis by specifically blocking the release of neuronal transmitters from peripheral nerve junctions. The current method for assessing the potency of botulinum toxin and antitoxins is the mouse LD50 assay. The mouse phrenic nerve-diaphragm assay is an in vitro assay that closely mimics in vivo respiratory paralysis. In this study, we have further improved the assay by using gelatin as a non-frothing alternative to albumin and investigated the effects of botulinum toxin serotypes A, B and E on phrenic nerve-hemidiaphragms from out-bred MF1 and in-bred Balb/c mice. Improved reproducibility was found with in-bred mice. Balb/c mice were also found to be much less sensitive to type B toxin perhaps indicating differences in the expression of receptor components. Hemidiaphragm preparations from Balb/c mice were approximately 7 times more sensitive to type A toxin and 7-12 times more sensitive to type E toxin relative to type B toxin. These findings indicate that when fully optimised the mouse nerve-diaphragm preparation can provide a functional in vitro model for accurate and reproducible assessment of toxin activity.

The structure of the Au(111)/methylthiolate interface: new insights from near-edge x-ray absorption spectroscopy and x-ray standing waves.

The local structure of the Au(111)(square root(3) x square root(3))R30 degrees-methylthiolate surface phase has been investigated by S K-edge near-edge s-ray absorption fine structure (NEXAFS) both experimentally and theoretically and by experimental normal-incidence x-ray standing waves (NIXSW) at both the C and S atomic sites. NEXAFS shows not only excitation into the intramolecular sigma(*) S-C resonance but also into a sigma(*) S-Au orbital perpendicular to the surface, clearly identifying the local S headgroup site as atop a Au atom. Simulations show that it is not possible, however, to distinguish between the two possible adatom reconstruction models; a single thiolate species atop a hollow-site Au adatom or a dithiolate moiety comprising two thiolate species bonded to a bridge-bonded Au adatom. Within this dithiolate moiety a second sigma(*) S-Au orbital that lies near parallel to the surface has a higher energy that overlaps that of the sigma(*) S-C resonance. The new NIXSW data show the S-C bond to be tilted by 61 degrees relative to the surface normal, with a preferred azimuthal orientation in <211>, corresponding to the intermolecular nearest-neighbor directions. This azimuthal orientation is consistent with the thiolate being atop a hollow-site Au adatom, but not consistent with the originally proposed Au-adatom-dithiolate moiety. However, internal conformational changes within this species could, perhaps, render this model also consistent with the experimental data.

Development of improved SNAP25 endopeptidase immuno-assays for botulinum type A and E toxins.

Botulinum neurotoxins contain proteases that cleave specific intra-neural proteins essential for neurotransmitter release. Toxin types A, E and C1 intra-cellularly cleave SNAP25 resulting in a flaccid paralysis. As a consequence, various different endopeptidase assays have been developed to specifically detect the toxins enzymatic activity, however, many of these suffer from variability, low sensitivity or unwanted interference exerted by product specific excipients. The current studies utilised solid phase synthesized SNAP25(137-206) peptide substrate, and specific antibody to either the SNAP25(190-197) or (173-180) octapeptide epitopes that become exposed following cleavage by toxin types A or E respectively. Assay sensitivity was increased 50 fold by the use of an optimal 0.5% Tween 20 concentration in tandem to 0.1% albumin together with an improved, simplified assay design without a pre-activation / reduction step. Sensitivities capable of detecting 0.01 LD50/ml (40fg/ml or 0.3fM) of type A toxin was achieved with a linear dose response between 0.1 and 1 LD50/ml. This provides sufficient sensitivity and precision (inter assay GCV of < 2%) for monitoring activity within any current or newly marketed therapeutic products containing less units per vial and may also make it applicable for other applications. Both purified haemagglutinin free and complexed toxins could be detected equally. Unlike type A, type E activity could unexpectedly be detected in the complete absence of reducing conditions and the optimal assay had a limit of detection of 0.2LD50/ml (4.8pg/ml) with a linear dose response between 1 and 10LD50/ml. The principle of using a detecting antibody to a substrate sequence buried within the native substrates alpha-helix may be further expanded to other specific enzyme cleavage reactions in the future.

LKB1 deficiency in T cells promotes the development of gastrointestinal polyposis.

Germline mutations in STK11, which encodes the tumor suppressor liver kinase B1 (LKB1), promote Peutz-Jeghers syndrome (PJS), a cancer predisposition syndrome characterized by the development of gastrointestinal (GI) polyps. Here, we report that heterozygous deletion of Stk11 in T cells (LThet mice) is sufficient to promote GI polyposis. Polyps from LThet mice, Stk11+/- mice, and human PJS patients display hallmarks of chronic inflammation, marked by inflammatory immune-cell infiltration, signal transducer and activator of transcription 3 (STAT3) activation, and increased expression of inflammatory factors associated with cancer progression [interleukin 6 (IL-6), IL-11, and CXCL2]. Targeting either T cells, IL-6, or STAT3 signaling reduced polyp growth in Stk11+/- animals. Our results identify LKB1-mediated inflammation as a tissue-extrinsic regulator of intestinal polyposis in PJS, suggesting possible therapeutic approaches by targeting deregulated inflammation in this disease.

Paradoxical enhancement of atherosclerosis by probucol treatment in apolipoprotein E-deficient mice.

Dietary administration of probucol (0.5%, wt/wt) efficiently reduced total plasma cholesterol levels in apolipoprotein E-deficient mice (apoE-/-) by 40%, with decreases in high density lipoprotein (HDL) and apoAI by 70 and 50%, respectively. Paradoxically, however, aortic atherosclerotic plaques in the probucol-treated apoE-/- mice formed more rapidly than in the untreated apoE-/- mice, and the lesions were two to four times larger and more mature regardless of sex, age, and genetic background (P < 10(-)6). Histologically, lesions in probucol-treated mice contained increased fibrous materials and cells other than foam cells, and were commonly associated with focal inflammation and aneurysmal dilatation. Probucol treatment also accelerated lesion development in apoE+/- mice fed an atherogenic diet, indicating that the adverse effect is not dependent on the complete absence of apoE. Furthermore, mice lacking apoE and apoAI have plasma lipoprotein profiles very similar to the probucol-treated apoE-/- mice, but do not have accelerated plaque development. Thus, the enhanced atherosclerosis in the probucol-treated animals is unlikely to be caused by the reduction of HDL and apoAI levels. Our data indicate that a reduction in plasma cholesterol caused by probucol does not necessarily lead to an antiatherogenic effect.

Botulinum type A toxin neutralisation by specific IgG and its fragments: a comparison of mouse systemic toxicity and local flaccid paralysis assays.

In this study, we have compared two in vivo assay methods to measure the type A botulinum toxin neutralising activity of specific immunoglobulin G (IgG) and its fragments (F(ab')(2), Fab', Fab) purified from pentavalent botulinum antisera raised in goats. Each assay method was repeated on three separate occasions in mice and relative potencies calculated with respect to a type A equine reference antitoxin. The conventional assay, which measures the number of mice surviving typically after 72 or 96 h following the intraperitoneal administration of a mixture of toxin and antitoxin, gave the following order of potency IgG>F(ab')(2)>Fab'>Fab (6.8>4.7>3.5>2.6 IU/mg). Differences in potency are likely to be due to differences in the pharmacokinetics of the antitoxins, which are related to their molecular weight. The alternative local flaccid paralysis assay, where toxin and antitoxin are injected subcutaneously into the left inguinocrural region, gave results with a narrower range of activities: IgG>Fab'>F(ab')(2)>Fab (6.0>5.9>5.5>4.6 IU/mg). Comparison of the two assay methods showed no significant differences for IgG, F(ab')(2) or Fab', although the Fab fragment was significantly more potent in the non-lethal assay probably because of the reduced influence of antitoxin pharmacokinetics in this localised assay. These findings show that a local flaccid paralysis assay provides a less time consuming and more humane alternative to the lethal assay for the potency testing of botulinum IgG and F(ab')(2) antitoxins.

Pulsatile insulin has greater hypoglycemic effect than continuous delivery.

The relative hypoglycemic effects of pulsatile versus steadily infused insulin have been examined in six normal subjects in whom pancreatic insulin output was suppressed by somatostatin-14. Soluble insulin was infused continuously overnight on one occasion and on another occasion the same quantity was given in pulses of 2-min duration with a gap of 11 min. The mean plasma glucose concentrations were lower when pulsed insulin was given [mean for the last hour: 4.66 +/- 0.08 mmol/L (+/- SEM) versus 5.53 +/- 0.06 mmol/L (+/- SEM) for steady infusion], diverging significantly (P less than 0.05 paired t test) 7 h after the start of the study. The specific binding of 125I(A14)mono-iodo-insulin to monocytes was greater after pulsed insulin (2.9% with pulsed versus 2.4% with steadily infused insulin at tracer-only point; P less than 0.02 paired t test). Thus, intravenous insulin has greater hypoglycemic effect when pulsed, possibly mediated by greater insulin receptor binding.