Cardiac function and microsphere blood flow distribution in the brain-dead dog

The mechanisms for the deterioration of the brain-dead organ donor are not clearly defined. We measured myocardial blood flow and function during the 4 hours after the induction of brain death in dogs. Brain death was induced by elevating and maintaining intracranial pressure above systolic arterial pressure and effectively stopping central nervous system blood flow. Multiorgan blood flow and systemic arteriovenous shunting were measured using radioactive microspheres. The mean arterial pressure was found to decrease markedly with the induction of brain death. The initial changes in mean arterial pressure were attributed to a decrease of systemic vascular resistance, with the more terminal changes due to a decrease in cardiac index. There was a marked decrease of left ventricular dP/dt with the induction of brain death and a gradual decrease of stroke volume despite no change in pulmonary capillary wedge pressure. The microsphere calculated blood flows to the left ventricle and septum of the myocardium were significantly lower at the 1- and 4-hour time points relative to control. However, the coronary sinus oxygen extraction ratio was not statistically different from control at 4 hours. Systemic arteriovenous shunts increased after the induction of brain death but remained below 10%. We conclude that despite brain death-induced hypotension, there is little evidence to suggest that marked myocardial hypoxic ischemic changes initiated the deterioration in this model.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29990/1/0000357.pd

Core-shell graphene oxide-polymer hollow fibers as water filters with enhanced performance and selectivity

Commercial hollow fiber filters for micro-and ultrafiltration are based on size exclusion and do not allow the removal of small molecules such as antibiotics. Here, we demonstrate that a graphene oxide (GO) layer can be firmly immobilized either inside or outside polyethersulfone-polyvinylpyrrolidone hollow fiber (Versatile PES®, hereafter PES) modules and that the resulting core-shell fibers inherits the microfiltration ability of the pristine PES fibers and the adsorption selectivity of GO. GO nanosheets were deposited on the fiber surface by filtration of a GO suspension through a PES cartridge (cut-off 0.1-0.2 μm), then fixed by thermal annealing at 80 °C, rendering the GO coating stably fixed and unsoluble. The filtration cut-off, retention selectivity and efficiency of the resulting inner and outer modified hollow fibers (HF-GO) were tested by performing filtration on water and bovine plasma spiked with bovine serum albumin (BSA, 66 kDa, ≈15 nm size), monodisperse polystyrene nanoparticles (52 nm and 303 nm sizes), with two quinolonic antibiotics (ciprofloxacin and ofloxacin) and rhodamine B (RhB). These tests showed that the microfiltration capability of PES was retained by HF-GO, and in addition the GO coating can capture the molecular contaminants while letting through BSA and smaller polystyrene nanoparticles. Combined XRD, molecular modelling and adsorption experiments show that the separation mechanism does not rely only on physical size exclusion, but involves intercalation of solute molecules between the GO layers

Ageing test of the ATLAS RPCs at X5-GIF

An ageing test of three ATLAS production RPC stations is in course at X5-GIF, the CERN irradiation facility. The chamber efficiencies are monitored using cosmic rays triggered by a scintillator hodoscope. Higher statistics measurements are made when the X5 muon beam is available. We report here the measurements of the efficiency versus operating voltage at different source intensities, up to a maximum counting rate of about 700Hz/cm^2. We describe the performance of the chambers during the test up to an overall ageing of 4 ATLAS equivalent years corresponding to an integrated charge of 0.12C/cm^2, including a safety factor of 5.Comment: 4 pages. Presented at the VII Workshop on Resistive Plate Chambers and Related Detectors; Clermont-Ferrand October 20th-22nd, 200

High-rate tests on Resistive Plate Chambers operated with eco-friendly gas mixtures

Results obtained by the RPC ECOgas@GIF++ Collaboration, using Resistive Plate Chambers operated with new, eco-friendly gas mixtures, based on Tetrafluoropropene and carbon dioxide, are shown and discussed in this paper. Tests aimed to assess the performance of this kind of detectors in high-irradiation conditions, analogous to the ones foreseen for the coming years at the Large Hadron Collider experiments, were performed, and demonstrate a performance basically similar to the one obtained with the gas mixtures currently in use, based on Tetrafluoroethane, which is being progressively phased out for its possible contribution to the greenhouse effect. Long term aging tests are also being carried out, with the goal to demonstrate the possibility of using these eco-friendly gas mixtures during the whole High Luminosity phase of the Large Hadron Collider.Comment: Submitted to European Physical Journal C on October 24, 2023, 15 pages, 14 figure

Preliminary results on the long term operation of RPCs with eco-friendly gas mixtures under irradiation at the CERN Gamma Irradiation Facility

Since 2019 a collaboration between researchers from various institutes and experiments (i.e. ATLAS, CMS, ALICE, LHCb/SHiP and the CERN EP-DT group), has been operating several RPCs with diverse electronics, gas gap thicknesses and detector layouts at the CERN Gamma Irradiation Facility (GIF++). The studies aim at assessing the performance of RPCs when filled with new eco-friendly gas mixtures in avalanche mode and in view of evaluating possible ageing effects after long high background irradiation periods, e.g. High-Luminosity LHC phase. This challenging research is also part of a task of the European AidaInnova project. A promising eco-friendly gas identified for RPC operation is the tetrafluoruropropene (C$_{3}$H$_{2}$F$_{4}$, commercially known as HFO-1234ze) that has been studied at the CERN GIF++ in combination with different percentages of CO$_2$. Between the end of 2021 and 2022 several beam tests have been carried out to establish the performance of RPCs operated with such mixtures before starting the irradiation campaign for the ageing study. Results of these tests for different RPCs layouts and different gas mixtures, under increasing background rates are presented here, together with the preliminary outcome of the detector ageing tests

Regulation of Septin Dynamics by the Saccharomyces cerevisiae Lysine Acetyltransferase NuA4

In the budding yeast Saccharomyces cerevisiae, the lysine acetyltransferase NuA4 has been linked to a host of cellular processes through the acetylation of histone and non-histone targets. To discover proteins regulated by NuA4-dependent acetylation, we performed genome-wide synthetic dosage lethal screens to identify genes whose overexpression is toxic to non-essential NuA4 deletion mutants. The resulting genetic network identified a novel link between NuA4 and septin proteins, a group of highly conserved GTP-binding proteins that function in cytokinesis. We show that acetyltransferase-deficient NuA4 mutants have defects in septin collar formation resulting in the development of elongated buds through the Swe1-dependent morphogenesis checkpoint. We have discovered multiple sites of acetylation on four of the five yeast mitotic septins, Cdc3, Cdc10, Cdc12 and Shs1, and determined that NuA4 can acetylate three of the four in vitro. In vivo we find that acetylation levels of both Shs1 and Cdc10 are reduced in a catalytically inactive esa1 mutant. Finally, we determine that cells expressing a Shs1 protein with decreased acetylation in vivo have defects in septin localization that are similar to those observed in NuA4 mutants. These findings provide the first evidence that yeast septin proteins are acetylated and that NuA4 impacts septin dynamics

Dermoscopy for early detection of facial lentigo maligna

Up until now, only lesions selected on the basis of their clinical atypia or which appear equivocal on naked eye examination have been shown to benefit from the use of dermoscopy. In our experience, dermoscopic evaluation of lesions located on the face may require a different approach, as a histopathological diagnosis of malignancy is not uncommon in clinically trivial lesions (i.e. lesions lacking the ABCD criteria for clinical suspicion). Moreover, at this site dermoscopy reveals specific criteria according to the particular histological architecture shown by sun-damaged skin. We report four cases of lentigo maligna (LM) of the face whose identification depended on dermoscopic examination which was performed routinely on all facial lesions, as the lesions did not show ABCD clinical criteria for malignancy. In our experience, the identification of early signs of malignancy by dermoscopy may indicate the excision of LM at an early phase, before the lesion is associated with the ABCD signs of melanoma. Dermatologists should avoid the mistake of immediately excluding a diagnosis of malignancy when examining an ABCD-negative pigmented skin lesion of the face. © 2005 British Association of Dermatologists