ResearchPad - veins https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Is transjugular insertion of a temporary pacemaker a safe and effective approach?]]> https://www.researchpad.co/article/elastic_article_13814 Temporary pacemakers (TPMs) are usually inserted in an emergency situation. However, there are few reports available regarding which route of access is best or what the most preferred approach is currently in tertiary hospitals. This study aimed to compare procedure times, complication rates, and indications for temporary pacing between the transjugular and transfemoral approaches to TPM placement. We analyzed consecutive patients who underwent TPM placement. Indications; procedure times; and rates of complications including localized infection, any bleeding, and pacing wire repositioning rates were analyzed. A total of 732 patients (361 treated via the transjugular approach and 371 treated via the transfemoral approach) were included. Complete atrioventricular block was the most common cause of TPM placement in both groups, but sick sinus syndrome was especially common in the transjugular approach group. Separately, procedure time was significantly shorter in the transjugular approach group (9.0 ± 8.0 minutes vs. 11.9 ± 9.7 minutes; P < 0.001). Overall complication rates were not significantly different between the two groups, and longer duration of temporary pacing was a risk factor for repositioning. The risk of reposition was significantly increased when the temporary pacing was continued more than 5 days and 3 days in the transjugular approach group and the transfemoral approach group, respectively. The transjugular approach should be considered if the TPM is required for more than 3 days.

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<![CDATA[Serum levels of bone sialoprotein correlate with portal pressure in patients with liver cirrhosis]]> https://www.researchpad.co/article/Nd170950f-0b0f-46af-a42d-6b06a3bc49ed

Liver cirrhosis represents the common end-stage of chronic liver diseases regardless of its etiology. Patients with compensated disease are mostly asymptomatic, however, progression to a decompensated disease stage is common. The available stratification strategies are often unsuitable to identify patients with a higher risk for disease progression and a limited prognosis. SIBLINGs, soluble glycophosphoproteins, are secreted into the blood by immune-cells. While osteopontin, the most prominent member of the SIBLINGs family, has been repeatedly associated with liver cirrhosis, data on the diagnostic and/or prognostic value of bone sialoprotein (BSP) are scarce and partly inconclusive. In this study, we analyzed the diagnostic and prognostic potential of circulating BSP in comparison to other standard laboratory markers in a large cohort of patients with liver cirrhosis receiving transjugular intrahepatic portosystemic shunt (TIPS). Serum levels of BSP were similar in patients with different disease stages and were not indicative for prognosis. Interestingly, BSP serum levels did correlate inversely with portal pressure, as well as its surrogates such as platelet count, the portal vein cross-sectional area and correlated positively with the portal venous velocity. In summary, our data highlight that BSP might represent a previously unrecognized marker for portal hypertension in patients with liver cirrhosis.

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<![CDATA[MRI, CT and high resolution macro-anatomical images with cryosectioning of a Beagle brain: Creating the base of a multimodal imaging atlas]]> https://www.researchpad.co/article/5c8acc89d5eed0c48498f996

Most common methods that directly show macro- or microscopic anatomy of the brain usually require the removal of the organ from the neurocranium. However, the brain can be revealed in situ by using proper sectioning techniques. Our aim was to both improve the cryosectioning method, test its limits and create a high-resolution macro-anatomical image series of a Beagle brain, which at the time of the study did not exist. A two-year-old female Beagle has been scanned with CT and MRI ante and post mortem, then the arteries of the head were filled with red resin. After freezing to -80°C, a neurocranium block was created and was embedded into a water-gelatin mix. Using a special milling device and a DSLR camera, 1112 consecutive RGB-color cryosections were made with a 100 μm layer thickness and captured in high resolution (300 dpi, 24-bit color, and pixel size was 19.5 x 19.5 μm). Image post-processing was done with Adobe Photoshop CS3 and Thermo Scientific Amira 6.0 softwares, and as a result of the proper alignment and coregistration, visualization and comparing was possible with all the applied imaging modalities (CT, MRI, cryosectioning) in any arbitrary plane. Surface models from the arteries, veins, brain and skull were also generated after segmentation in the same coordinate system, giving a unique opportunity for comparing the two-dimensional and three-dimensional anatomy. This is the first study which focuses directly to this high-definition multimodal visualization of the canine brain, and it provides the most accurate results compared to previous cryosectioning studies, as using an improved method, higher image quality, more detailed image, proper color fidelity and lower artefact formation were achieved. Based on the methodology we described, it can serve as a base for future multimodal (CT, MR, augmented- or virtual reality) imaging atlases for medical, educational and scientific purposes.

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<![CDATA[Hepatocellular carcinoma with extrahepatic metastasis: Are there still candidates for transarterial chemoembolization as an initial treatment?]]> https://www.researchpad.co/article/5c99029ed5eed0c484b98241

Background and aim

Currently, sorafenib is indicated for hepatocellular carcinoma (HCC) with extrahepatic metastasis (EHM), and many other systemic agents are becoming available. However, a few HCC patients with EHM still undergo transarterial chemoembolization (TACE) for intrahepatic tumor control. We aimed to investigate whether TACE is appropriate for patients with EHM, and if so, which subgroup may benefit from TACE.

Methods

A total of 186 consecutive HCC patients (median: 55 years, male: 86.0%, hepatitis B virus: 81.7%, Child-Pugh Class A: 83.3%) with EHM (nodal metastasis: 60.8%, distant metastasis: 39.2%) between 2010 and 2014 were analyzed. Initial treatment included sorafenib in 69 patients, and TACE in 117 patients.

Results

During a median follow-up of 6.6 months (range: 0.2–94.6 months), mortality was observed in 90.3% (168/186). The median survival was better for patients who received TACE than those treated with sorafenib (8.2 months vs. 4.6 months, p < 0.001). However, baseline characteristics varied between patients initially treated with TACE and sorafenib, and the treatment modality was not an independent factor associated with overall survival (hazard ratio: 1.19, 95% confidence interval: 0.81–1.75, p = 0.36). In sub-group analysis, TACE was associated with better survival only among younger patients and those with segmental/lobar portal vein invasion.

Conclusion

In HCC patients with EHM, TACE was not an independent favorable prognostic factor compared to sorafenib. The concept of intrahepatic control in HCC patients with EHM may need to be reevaluated in the era of promising systemic therapies, although there can be specific subgroups who still benefit from TACE.

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<![CDATA[Patency rates of arteriovenous fistulas created before versus after hemodialysis initiation]]> https://www.researchpad.co/article/5c58d614d5eed0c484031566

In an incident hemodialysis (HD) population, we aimed to investigate whether arteriovenous fistula (AVF) creation before HD initiation was associated with improved AVF patency compared with AVF creation from a central venous catheter (CVC), and also to compare patient survival between these patients. Between January 2011 and December 2013, 524 incident HD patients with identified first predialysis vascular access with an AVF (pre-HD group, n = 191) or an AVF from a CVC (on-HD group, n = 333) were included and analyzed retrospectively. The study outcome was defined as AVF patency and all-cause mortality (time to death). On Kaplan–Meier survival analysis, primary and secondary AVF patency rates did not differ significantly between the two groups (P = 0.812 and P = 0.586, respectively), although the overall survival rate was significantly higher in the pre-HD group compared with the on-HD group (P = 0.013). On multivariate analysis, well-known patient factors were associated with decreased primary (older age and diabetes mellitus [DM]) and secondary (DM and peripheral arterial occlusive disease) AVF patency, whereas use of a CVC as the initial predialysis access (hazard ratios, 1.84; 95% confidence intervals, 1.20–2.75; P = 0.005) was significantly associated with worse survival in addition to well-known patient factors (older age, diabetes mellitus, and peripheral arterial occlusive disease). Worse survival in the on-HD group was likely confounded by selection bias because of the retrospective nature of our study. Therefore, the observed lower mortality associated with AVF creation before HD initiation is not fully attributable to CVC use, but rather, affected by other patient-level prognostic factors. There were no CVC-related complications in the pre-HD group, whereas 10.2% of CVC-related complications were noted in the on-HD group. In conclusion, among incident HD patients, compared with patients who underwent creation of an AVF from a CVC, initial AVF creation showed similar primary and secondary AVF patency rates, but lower mortality risk. We also observed that an initial CVC use was an independent risk factor associated with worse survival. A fistula-first strategy might be the best option for incident HD patients who are good candidates for AVF creation.

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<![CDATA[Liver regeneration therapy through the hepatic artery-infusion of cultured bone marrow cells in a canine liver fibrosis model]]> https://www.researchpad.co/article/5c521890d5eed0c484798f50

Background

We previously reported regenerative therapies for decompensated cirrhosis based on peripheral venous drip infusion using non-cultured whole bone marrow (BM) cells, or the less invasive cultured BM-derived mesenchymal stem cells (BMSCs). Here, we assessed the efficacy and safety of hepatic arterial infusion using cultured autologous BMSCs, comparing it with peripheral infusion, using our established canine liver fibrosis model.

Methods

Canine BM cells were harvested and cultured, and the resultant BMSCs were returned to carbon tetrachloride (CCl4)-induced liver cirrhosis model canines via either a peripheral vein (Vein group) or hepatic artery (Artery group). A variety of assays were performed before and 4, 8, and 12 weeks after BMSC infusion, and liver fibrosis and indocyanine green (ICG) half-life (t1/2) were compared to those in a control group that received CCl4 but not BMSCs. The safety of this approach was evaluated by contrast-enhanced computed tomography (CT) and serial blood examinations after infusion.

Results

Four weeks after infusing BMSCs, a significant improvement was observed in the Vein group (n = 8) compared to outcome in the Control group (n = 10), along with a decrease in ICG t1/2. In the Artery group (n = 4), ICG t1/2 was significantly shorter than that in the Vein group at 8 weeks (Δt1/2: −3.8 ± 1.7 min vs. +0.4 ± 2.4 min; p < 0.01) and 12 weeks (Δt1/2: −4.2 ± 1.7 min vs. +0.4 ± 2.7 min; p < 0.01) after BMSC administration. Post-infusion contrast-enhanced CT showed no liver infarction, and blood tests showed no elevations in either serum lactate dehydrogenase concentrations or hypercoagulability.

Conclusions

We confirmed the efficacy and safety of the hepatic arterial infusion of cultured autologous BMSCs using a canine model, thereby providing non-clinical proof-of-concept.

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<![CDATA[The axillary vein and its tributaries are not in the mirror image of the axillary artery and its branches]]> https://www.researchpad.co/article/5c40f76dd5eed0c484386118

Introduction

The axillary and cephalic veins are used for various clinical purposes but their anatomy is not fully understood. Increased knowledge and information about them as well as superficial veins in the upper arm would be useful.

Objective

The aim of this study is to contribute to the literature regarding the anatomy of the venous drainage of the upper extremity.

Methods

The veins of forty upper extremities from twenty one adult cadavers were injected and their axillary regions dissected. The course and pattern of drainage of the venous tributaries in the axillary region were identified and recorded.

Results

The basilic, brachial, subscapular, lateral thoracic and superior thoracic veins drained mainly into the axillary vein, in common with most textbook descriptions. However, the thoracoacromial veins were observed to drain into the cephalic vein in 70.0% of upper limbs. In addition, a venous channel connecting the distal part and proximal part of the axilla was found along the posterolateral wall of the axilla in 77.5% of the upper limbs. In 95.0% of upper limbs, we discovered a superficial vein which ran from the axillary base and drained directly into the axillary vein.

Conclusion

The veins from the inferomedial part of the axilla drain into the axillary vein, whereas the veins from the superolateral part of the axilla drain into the cephalic vein. The venous drainage of the axilla is variable and in common with venous drainage elsewhere, does not necessarily follow the pattern of the arterial supply.

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<![CDATA[Borderline-resectable pancreatic adenocarcinoma: Contour irregularity of the venous confluence in pre-operative computed tomography predicts histopathological infiltration]]> https://www.researchpad.co/article/5c3667fcd5eed0c4841a6c6c

Purpose

The purpose of the current study was to compare CT-signs of portal venous confluence infiltration for actual histopathological infiltration of the vein or the tumor/vein interface (TVI) in borderline resectable pancreatic ductal adenocarcinoma (PDAC).

Methods and materials

101 patients with therapy-naïve, primarily resected PDAC of the pancreatic head without arterial involvement were evaluated. The portal venous confluence was assessed for contour irregularity (defined as infiltration) and degree of contact. The sensitivity and specificity of contour irregularity versus tumor to vein contact >180° as well as the combination of the signs for tumor cell infiltration of the vessel wall or TVI was calculated. Overall survival (OS) was compared between groups.

Results

Sensitivity and specificity of contour irregularity for identification of tumor infiltration of the portal venous confluence or the TVI was higher compared to tumor to vessel contact >180° for tumor cell infiltration (96%/79% vs. 91%/38% respectively, p<0.001). The combination of the signs increased specificity to 92% (sensitivity 88%). Patients with contour irregularity/ tumor to vein contact >180°/ both signs had significantly worse overall survival (16.2 vs. 26.5 months/ 17.9 vs. 37.4 months/ 18.5 vs. 26.5 months respectively, all p<0.05).

Conclusion

Portal venous confluence contour irregularity is a strong predictor of actual tumor cell infiltration of the vessel wall or the TVI and should be noted as such in radiological reports.

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<![CDATA[Inside the horn of plenty: Leaf-mining micromoth manipulates its host plant to obtain unending food provisioning]]> https://www.researchpad.co/article/5c269738d5eed0c48470ef63

Leaves represent the main resource for herbivorous insects and their performances are mainly a function of leaf nutritional quality. Two feeding strategies are known to optimize the exploitation of leaf resources: leaf-miners that selectively feed on tissues of high nutritional quality and gall-inducers that induce the development of a new tissue showing an enhanced nutritional value. Some leaf-miners are known to also manipulate their nutritional environment, but do not affect plant development. Cases of callus proliferation in leaf-mines have been reported, however, the direct role of the insect in the formation of additional plant cells and the nutritional function of this tissue have never been established. Using an experimental approach, we show that leaf-mining larvae of micromoth, Borboryctis euryae (Lepidoptera: Gracillariidae), that grow on Eurya japonica (Pentaphylacaceae), actively induce callus proliferation within their leaf-mine at the fourth instar. We experimentally demonstrated that, at this developmental stage, the larva feeds exclusively on this newly formed tissue and feeding of the tissue is essential for completing larval stage. Phenological census revealed considerable expansion and variation of fourth instar duration caused by the continuous production of callus. We propose here the “cornucopia” hypothesis which states that the newly produced callus induced by the leaf-mining larvae provides virtually unending nourishment, which in turn allows flexible larval development time. This represents the first example of a leaf-miner manipulating plant development to its benefit, like a gall-inducer. We propose to name this life style “mine-galler”.

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<![CDATA[Morphological variations of the interatrial septum in ovine heart]]> https://www.researchpad.co/article/5c23f280d5eed0c484047051

Smooth septum interatrial septum, patent foramen ovale (PFO) channel and atrial septal pouches (SPs) are commonly described variants in humans. Recent discoveries on the clinical significance of left-sided SP may encourage the creation of new strategies and devices for the management of SPs. However, these strategies may first be tested in the ovine model before implementation in humans. Unfortunately, little is known about the presence of SPs in ovine. In this study a total of 60 ovine (Ovis aries) hearts were examined. The interatrial septum morphology was assessed and the PFO channel and SPs were measured. The most commonly occurring variant were PFO channels (25.0%) with channel lengths of 5.4±2.3 mm. Smooth septums were observed in 18.3% of hearts. In the remaining cases, septums had a left septal ridge (15.0%), left SP (11.7%), left septal bridge (10.0%), right SP (10.0%), or had both a right SP and left septal ridge (10.0%). No double SPs were observed. The mean right SP depth was 3.4 ± 1.2 mm, and its mean ostium width and height were 7.9±1.8 mm and 2.8±1.0, respectively. For the left SP, the mean depth was 6.0±1.7mm, the ostium width was 7.9±2.4mm, and the ostium height was 4.1±1.6mm (range: 2.3–6.4mm). In conclusion the interatrial septum of ovine hearts exhibit morphologies that are more similar to humans than they are to swine, which should be taken into account during experimental studies. The presence of a left SP in sheep hearts make ovine models a promising alternative to the human heart for developing left-sided SP management devices and techniques.

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<![CDATA[Beyond interferon side effects: What residual barriers exist to DAA hepatitis C treatment for people who inject drugs?]]> https://www.researchpad.co/article/5c0ae476d5eed0c484589c12

Recent advances in the efficacy and tolerability of hepatitis C treatments and the introduction of a universal access scheme for the new Direct Acting Antiviral (DAA) therapies in March 2016, has resulted in a rapid increase in the uptake of hepatitis C treatment in Australia. Despite these positive developments, recent data suggest a plateauing of treatment numbers, indicating that more work may need to be done to identify and address ongoing barriers to hepatitis C treatment access and uptake. This paper aims to contribute to our understanding of the ongoing barriers to DAA therapies, with a focus on people who inject drugs. The paper draws on participant interview data from a qualitative research study based on a participatory research design that included a peer researcher with direct experience of both hepatitis C DAA treatment and injecting drug use at all stages of the research process. The study’s findings show that residual barriers to DAA treatment exist at personal, provider and system levels and include poor venous access, DAA treatments not considered ‘core-business’ by opioid substitution treatment (OST) providers, and patients having to manage multiple health and social priorities that interfere with keeping medical appointments such as childcare and poor access to transport services. Further, efforts to increase access to and uptake of DAA hepatitis C treatment over time will require a focus on reducing stigma and discrimination towards people who inject drugs as this remains as a major barrier to care for many people.

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<![CDATA[Anatomic measurements of cerebral venous sinuses in idiopathic intracranial hypertension patients]]> https://www.researchpad.co/article/5b28b404463d7e129299938f

Purpose

Magnetic resonance venography (MRV) has not been validated in pre-operative planning of the dural venous sinus stenting (VSS) among idiopathic intracranial hypertension (IIH) patients. We aim to prospectively evaluate dural venous sinus measurement in IIH patient population on two-dimensional time-of-flight (2D-TOF) MRV and Three-dimensional contrast-enhanced (3D-CE) MRV acquisitions and compare them against real-time endoluminal measurements with intravascular ultrasound (IVUS), served as the reference.

Materials and methods

The study has been approved by the Weill Cornell Medicine institutional review board. All patients signed written informed consent approved by IRB. Prospective evaluation of forty-five consecutive IIH patients treated with VSS at our institution were evaluated. Patients with pre-stent magnetic resonance venography (MRV) ≤ 6-months of VSS and intravascular ultrasound (IVUS) during VSS constituted the study population. Maximum diameter (in mm), Area (in cm2) and Perimeter (in cm) were measured at posterior 1/3rd of superior sagittal sinus (SSS), proximal transverse sinus (PTS), proximal sigmoid sinus (PSS) and mid sigmoid sinus (MSS) on 2D-TOF-MRV, 3D-CE-MRV and IVUS. Statistical analysis performed using box and whisker plots, Bland-Altman analysis and paired sample t-test.

Results

Twenty (n = 20) patients constituted our study population. The mean age was 30±11 years (7–59 years) and 18 out of 20 were female patients. Mean weight and BMI (range) were 86.3±18.3 kilograms (30.8–107.5 kgs) and 32.9±6.8 kg/M2 (16.4–48.3kg/M2) respectively. The CE-MRV significantly oversized the cerebral venous sinuses compared to TOF-MRV (Dmax: +2.0±1.35 mm, p<0.001; Area: +13.31±10.92 mm2, p<0.001 and Perimeter: +4.79±3.4 mm, p<0.001) and IVUS (Dmax: +1.52±2.16 mm, p<0.001; Area: +10.03±21.5 mm2, p<0.001 and Perimeter: +4.15±3.27 mm, p<0.001). The TOF-MRV sinus measurements were in good agreement with the IVUS measurements with no significant variation (Dmax: +.21±2.23 mm, p = 0.49; Area: +2.51±20.41mm2, p = 0.347 and Perimeter: +.001±1.11 mm, p = 0.991).

Conclusion

We report baseline cerebral venous sinus measurements (maximum diameter, area and perimeter) in patients with idiopathic intracranial hypertension. In our experience, TOF-MRV is a reliable representation of endoluminal cerebral venous sinus dimensions, and CE-MRV measurements reflected an overestimation of the endoluminal sinus dimensions when compared against the real time IVUS measurements.

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<![CDATA[Impact of positive end expiratory pressure on cerebral hemodynamic in paediatric patients with post-traumatic brain swelling treated by surgical decompression]]> https://www.researchpad.co/article/5b03d274463d7e6e6b5b7908

Introduction

The objective of our present study is to evaluate the impact of different PEEP levels on cerebral hemodynamic, gas exchanges and respiratory system mechanics in paediatric patients with post-traumatic brain swelling treated with decompressive craniectomy (DC).

Materials and methods

A prospective physiologic study was carried out on 14 paediatric patients presenting with severe traumatic brain swelling treated with DC. Transcranial Doppler ultrasonography was performed on the middle cerebral artery bilaterally after DC. After assessment at ZEEP, intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean arterial pressure (MAP), central venous pressure (CVP) and gas exchanges were recorded at PEEP 4 and PEEP 8.

Results

From ZEEP to PEEP 8, the compliance of respiratory system indexed to the weight of the patient significantly increased (P = 0.02) without ICP modifications. No significant variation of the MAP, CPP, Vmed, the total resistance of respiratory system and ohmic resistance of the respiratory system indexed to the weight of the patients was observed. CVP significantly increased between ZEEP and PEEP 8 (P = 0.005), and between PEEP 4 and PEEP 8 (P = 0.05).

Conclusions

PEEP values up to 8 cmH20 seem to be safe in paediatric patients with a severe post-traumatic brain swelling treated with DC.

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<![CDATA[Macrophage Depletion Attenuates Extracellular Matrix Deposition and Ductular Reaction in a Mouse Model of Chronic Cholangiopathies]]> https://www.researchpad.co/article/5989da20ab0ee8fa60b7e798

Chronic cholangiopathies, such as primary and secondary sclerosing cholangitis, are progressive disease entities, associated with periportal accumulation of inflammatory cells, encompassing monocytes and macrophages, peribiliary extracellular matrix (ECM) deposition and ductular reaction (DR). This study aimed to elucidate the relevance of macrophages in the progression of chronic cholangiopathies through macrophage depletion in a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) mouse model. One group of mice received a single i.p. injection of Clodronate encapsulated liposomes (CLOLipo) at day 7 of a 14 day DDC treatment, while control animals were co-treated with PBSLipo instead. Mice were sacrificed after 7 or respectively 14 days of treatment for immunohistochemical assessment of macrophage recruitment (F4/80), ECM deposition (Sirius Red, Laminin) and DR (CK19). Macrophage depletion during a 14 day DDC treatment resulted in a significant inhibition of ECM deposition. Porto-lobular migration patterns of laminin-rich ECM and ductular structures were significantly attenuated and a progression of DR was effectively inhibited by macrophage depletion. CLOLipo co-treatment resulted in a confined DR to portal regions without amorphous cell clusters. This study suggests that therapeutic options selectively directed towards macrophages might represent a feasible treatment for chronic cholestatic liver diseases.

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<![CDATA[Novel Rat Model of Repetitive Portal Venous Embolization Mimicking Human Non-Cirrhotic Idiopathic Portal Hypertension]]> https://www.researchpad.co/article/5989d9e3ab0ee8fa60b6a506

Background

Non-cirrhotic idiopathic portal hypertension (NCIPH) is characterized by splenomegaly, anemia and portal hypertension, while liver function is preserved. However, no animal models have been established yet. This study assessed a rat model of NCIPH and characterized the hemodynamics, and compared it to human NCIPH.

Methods

Portal pressure (PP) was measured invasively and coloured microspheres were injected in the ileocecal vein in rats. This procedure was performed weekly for 3 weeks (weekly embolization). Rats without and with single embolization served as controls. After four weeks (one week after last embolization), hemodynamics were investigated, hepatic fibrosis and accumulation of myofibroblasts were analysed. General characteristics, laboratory analyses and liver histology were collected in patients with NCIPH.

Results

Weekly embolization induced a hyperdynamic circulation, with increased PP. The mesenteric flow and hepatic hydroxyproline content was significantly higher in weekly embolized compared to single embolized rats (mesenteric flow +54.1%, hydroxyproline +41.7%). Mesenteric blood flow and shunt volumes increased, whereas splanchnic vascular resistance was decreased in the weekly embolization group. Fibrotic markers αSMA and Desmin were upregulated in weekly embolized rats.

Discussion

This study establishes a model using repetitive embolization via portal veins, comparable with human NCIPH and may serve to test new therapies.

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<![CDATA[4D flow MRI assessment of right atrial flow patterns in the normal heart – influence of caval vein arrangement and implications for the patent foramen ovale]]> https://www.researchpad.co/article/5989db50ab0ee8fa60bdbdb1

Aim

To investigate atrial flow patterns in the normal adult heart, to explore whether caval vein arrangement and patency of the foramen ovale (PFO) may be associated with flow pattern.

Materials and Methods

Time-resolved, three-dimensional velocity encoded magnetic resonance imaging (4D flow) was employed to assess atrial flow patterns in thirteen healthy subjects (6 male, 40 years, range 25–50) and thirteen subjects (6 male, 40 years, range 21–50) with cryptogenic stroke and patent foramen ovale (CS-PFO). Right atrial flow was defined as vortical, helico-vortical, helical and multiple vortices. Time-averaged and peak systolic and diastolic flows in the caval and pulmonary veins and their anatomical arrangement were compared.

Results

A spectrum of right atrial flow was observed across the four defined categories. The right atrial flow patterns were strongly associated with the relative position of the caval veins. Right atrial flow patterns other than vortical were more common (p = 0.015) and the separation between the superior and inferior vena cava greater (10±5mm versus 3±3mm, p = 0.002) in the CS-PFO group. In the left atrium all subjects except one had counter-clockwise vortical flow. Vortex size varied and was associated with left lower pulmonary vein flow (systolic r = 0.61, p = 0.001, diastolic r = 0.63 p = 0.002). A diastolic vortex was less common and time-averaged left atrial velocity was greater in the CS-PFO group (17±2cm/sec versus 15±1, p = 0.048). One CS-PFO subject demonstrated vortical retrograde flow in the descending aortic arch; all other subjects had laminar descending aortic flow.

Conclusion

Right atrial flow patterns in the normal heart are heterogeneous and are associated with the relative position of the caval veins. Patterns, other than ‘typical’ vortical flow, are more prevalent in the right atrium of those with cryptogenic stroke in the context of PFO. Left atrial flow patterns are more homogenous in normal hearts and show a relationship with flow arising from the left pulmonary veins.

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<![CDATA[Papaverine Prevents Vasospasm by Regulation of Myosin Light Chain Phosphorylation and Actin Polymerization in Human Saphenous Vein]]> https://www.researchpad.co/article/5989dad6ab0ee8fa60bb7eee

Objective

Papaverine is used to prevent vasospasm in human saphenous veins (HSV) during vein graft preparation prior to implantation as a bypass conduit. Papaverine is a nonspecific inhibitor of phosphodiesterases, leading to increases in both intracellular cGMP and cAMP. We hypothesized that papaverine reduces force by decreasing intracellular calcium concentrations ([Ca2+]i) and myosin light chain phosphorylation, and increasing actin depolymerization via regulation of actin regulatory protein phosphorylation.

Approach and Results

HSV was equilibrated in a muscle bath, pre-treated with 1 mM papaverine followed by 5 μM norepinephrine, and force along with [Ca2+]i levels were concurrently measured. Filamentous actin (F-actin) level was measured by an in vitro actin assay. Tissue was snap frozen to measure myosin light chain and actin regulatory protein phosphorylation. Pre-treatment with papaverine completely inhibited norepinephrine-induced force generation, blocked increases in [Ca2+]i and led to a decrease in the phosphorylation of myosin light chain. Papaverine pre-treatment also led to increased phosphorylation of the heat shock-related protein 20 (HSPB6) and the vasodilator stimulated phosphoprotein (VASP), as well as decreased filamentous actin (F-actin) levels suggesting depolymerization of actin.

Conclusions

These results suggest that papaverine-induced force inhibition of HSV involves [Ca2+]i-mediated inhibition of myosin light chain phosphorylation and actin regulatory protein phosphorylation-mediated actin depolymerization. Thus, papaverine induces sustained inhibition of contraction of HSV by the modulation of both myosin cross-bridge formation and actin cytoskeletal dynamics and is a pharmacological alternative to high pressure distention to prevent vasospasm.

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<![CDATA[Increased Inlet Blood Flow Velocity Predicts Low Wall Shear Stress in the Cephalic Arch of Patients with Brachiocephalic Fistula Access]]> https://www.researchpad.co/article/5989dacbab0ee8fa60bb43fd

Background

An autogenous arteriovenous fistula is the optimal vascular access for hemodialysis. In the case of brachiocephalic fistula, cephalic arch stenosis commonly develops leading to access failure. We have hypothesized that a contribution to fistula failure is low wall shear stress resulting from post-fistula creation hemodynamic changes that occur in the cephalic arch.

Methods

Twenty-two subjects with advanced renal failure had brachiocephalic fistulae placed. The following procedures were performed at mapping (pre-operative) and at fistula maturation (8–32 weeks post-operative): venogram, Doppler to measure venous blood flow velocity, and whole blood viscosity. Geometric and computational modeling was performed to determine wall shear stress and other geometric parameters. The relationship between hemodynamic parameters and clinical findings was examined using univariate analysis and linear regression.

Results

The percent low wall shear stress was linearly related to the increase in blood flow velocity (p < 0.01). This relationship was more significant in non-diabetic patients (p < 0.01) than diabetic patients. The change in global measures of arch curvature and asymmetry also evolve with time to maturation (p < 0.05).

Conclusions

The curvature and hemodynamic changes during fistula maturation increase the percentage of low wall shear stress regions within the cephalic arch. Low wall shear stress may contribute to subsequent neointimal hyperplasia and resultant cephalic arch stenosis. If this hypothesis remains tenable with further studies, ways of protecting the arch through control of blood flow velocity may need to be developed.

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<![CDATA[Cranial Morphology of the Late Oligocene Patagonian Notohippid Rhynchippus equinus Ameghino, 1897 (Mammalia, Notoungulata) with Emphases in Basicranial and Auditory Region]]> https://www.researchpad.co/article/5989daafab0ee8fa60baa992

“Notohippidae” is a probably paraphyletic family of medium sized notoungulates with complete dentition and early tendency to hypsodonty. They have been recorded from early Eocene to early Miocene, being particularly diverse by the late Oligocene. Although Rhynchippus equinus Ameghino is one of the most frequent notohippids in the fossil record, there are scarce data about cranial osteology other than the classical descriptions which date back to the early last century. In this context, we describe the exceptionally preserved specimen MPEF PV 695 (based on CT scanning technique and 3D reconstruction) with the aim of improving our knowledge of the species, especially regarding auditory region (petrosal, tympanic and surrounding elements), sphenoidal and occipital complexes. Besides a modular description of the whole skull, osteological correlates identified on the basicranium are used to infer some soft-tissue elements, especially those associated with vessels that supply the head, mainly intracranially. One of the most informative elements was the petrosal bone, whose general morphology matches that expected for a toxodont. The endocranial surface, together with the surrounding parietal, basisphenoid, occipital, and squamosal, enabled us to propose the location and communication of main venous sinuses of the lateral head wall (temporal, inferior and sigmoid sinuses), whereas the tympanic aspect and the identification of a posterior carotid artery canal provided strong evidence in support of an intratympanic course of the internal carotid artery, a controversial issue among notoungulates. Regarding the arrangement of tympanic and paratympanic spaces, the preservation of the specimen allowed us to appreciate the three connected spaces that constitute a heavily pneumatized middle ear; the epitympanic sinus, the tympanic cavity itself, and the ventral expansion of the tympanic cavity through the notably inflated bullae. We hope this study stimulates further inquires and provides potentially informative data for future research involving other representatives of the order.

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<![CDATA[Prognostic value of cerebral tissue oxygen saturation during neonatal extracorporeal membrane oxygenation]]> https://www.researchpad.co/article/5989db51ab0ee8fa60bdc4d5

Objectives

Extracorporeal membrane oxygenation support is indicated in severe and refractory respiratory or circulatory failures. Neurological complications are typically represented by acute ischemic or hemorrhagic lesions, which induce higher morbidity and mortality. The primary goal of this study was to assess the prognostic value of cerebral tissue oxygen saturation (StcO2) on mortality in neonates and young infants treated with ECMO. A secondary objective was to evaluate the association between StcO2 and the occurrence of cerebral lesions.

Study design

This was a prospective study in infants < 3 months of age admitted to a pediatric intensive care unit and requiring ECMO support.

Measurements

The assessment of cerebral perfusion was made by continuous StcO2 monitoring using near-infrared spectroscopy (NIRS) sensors placed on the two temporo-parietal regions. Neurological lesions were identified by MRI or transfontanellar echography.

Results

Thirty-four infants <3 months of age were included in the study over a period of 18 months. The ECMO duration was 10±7 days. The survival rate was 50% (17/34 patients), and the proportion of brain injuries was 20% (7/34 patients). The mean StcO2 during ECMO in the non-survivors was reduced in both hemispheres (p = 0.0008 right, p = 0.03 left) compared to the survivors. StcO2 was also reduced in deceased or brain-injured patients compared to the survivors without brain injury (p = 0.002).

Conclusion

StcO2 appears to be a strong prognostic factor of survival and of the presence of cerebral lesions in young infants during ECMO.

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