328 research outputs found

    Micromixing and microchannel design: Vortex shape and entropy

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    This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.In very recent years microdevices, due to their potency in replacing large-scale conventional laboratory instrumentation, are becoming a fast and low cost technology for the treatment of several chemical and biological processes. In particular microfluidics has been massively investigated, aiming at improving the performance of chemical reactors. This is because of the fact that reaction is often an interface phenomenon where the greater the surface to volume ratio, the higher the reaction speed, and microscale mixing increases the interfacial area (in terms of mixing-induced-by-vortices generation). However, microfluidic systems suffer from the limitation that they are characterized mostly by very low Reynolds numbers, with the consequence that (i) they cannot take advantage from the turbulence mixing support, and (ii) viscosity hampers proper vortex detection. Therefore, the proper design of micro-channels (MCs) becomes essential. In this framework, several geometries have been proposed to induce mixing vortices in MCs. However a quantitative comparison between proposed geometries in terms of their passive mixing potency can be done only after proper definition of vortex formation (topology, size) and mixing performance. The objective of this study is to test the ability of different fluid dynamic metrics in vortex detection and mixing effectiveness in micromixers. This is done numerically solving different conditions for the flow in a classic passive mixer, a ring shaped MC. We speculate that MCs design could take advantage from fluidic metrics able to rank properly flow related mixing

    Multifocal gastrointestinal angiosarcoma: A challenging diagnosis?

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    Angiosarcoma rarely involves the gastrointestinal tract. Herein, we describe the case of a 68-year-old man with haemoptysis and melena who was eventually diagnosed with multifocal angiosarcoma of the stomach, small bowel, lungs, and thyroid. The peculiarity was that the histological feature of the polypoid lesions removed at endoscopy was initially misinterpreted as benign hyperplastic polyps, whilst their neoplastic nature was clinically suspected only when the videocapsule endoscopy revealed the presence of multiple variable-sized nodules with apical erosion or active bleeding in the small bowel. Based on the very low incidence, diagnosis of angiosarcoma involving the gastrointestinal tract may be misinterpreted by both the endoscopist and pathologist

    Hypoalbuminaemia and heart failure: A practical review of current evidence

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    Hypoalbuminaemia (serum albumin levels <= 3.5 g/dl) is associated with poor outcomes among patients with heart failure (HF). This narrative review includes original articles and reviews published over the past 20 years and retrieved from PubMed using the following search terms (or their combination): 'heart failure', 'hypoalbuminaemia', 'heart failure with reduced ejection fraction', 'heart failure with preserved ejection fraction', 'all-cause mortality', 'in-hospital mortality', 'hospitalization', 'prognosis'. The aims of this review are to provide an overview on the prevalence of hypoalbuminaemia in HF, its impact on clinical outcomes, and potential mechanisms that may suggest future therapeutic strategies. Hypoalbuminaemia is frequent in HF patients, especially among the elderly. However, data about the exact epidemiology of hypoalbuminaemia are scant due to different definitions, and prevalence is estimated between 5% and 70% across the whole spectrum of ejection fraction. Current evidence points to hypoalbuminaemia as a marker of poor outcomes in HF, irrespective of the ejection fraction, and in other cardiovascular diseases. Among patients who suffered from acute coronary syndrome, those with hypoalbuminaemia had an increased risk of new-onset HF and in-hospital mortality. Albumin, however, might also play a role in the natural history of such diseases due to its antioxidant, anti-inflammatory, and antithrombotic properties. Whether albumin supplementation or nutritional support in general would be beneficial in improving clinical outcomes in HF is not completely clear and should be evaluated in adequately designed studies

    Genomic changes of chromosomes 8p23.1 and 1q21: Novel mutations in malignant mesothelioma

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    Introduction: Malignant mesothelioma is an aggressive malignancy of the thoracic cavity caused by prior asbestos exposure. In the peritoneum the mesothelioma is an extremely rare condition. In the present preliminary study, high-resolution array-comparative genomic hybridization (a-CGH) was performed to identify genetic imbalances in a series of malignant peritoneal mesothelioma cases. Materials and methods: Between 1990 and 2008, among the cases recorded in the Apulia Mesothelioma Register, we found 22 peritoneal mesothelioma cases. CGH-array was performed on samples from all patients. Results: The CGH-array analysis revealed multiple chromosomal imbalances. Interestingly, deletion at 8p23.1 was observed in 12 cases. Furthermore, another novel deletion at 1q21 was present in 11. Often, 1q21 and 8p23.1 losses were present in the same patient (7 cases). Losses of BAP1 and CDKN2A loci were not detected. Discussion: The region at 8p23.1 contains the beta-defensin gene cluster (DEF) and 1q21 contains ubiquitin conjugating enzyme E2 (UBE2Q1). We hypotesized that the loss of function of ubiquitination, as well as of the defensins, could play an important role in the initial development and subsequent progression of mesothelioma

    Structural elements of metal selectivity in metal sensor proteins

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    Staphylococcus aureus CzrA and Mycobacterium tuberculosis NmtR are homologous zinc/cobalt-responsive and nickel/cobalt-responsive transcriptional repressors in vivo, respectively, and members of the ArsR/SmtB superfamily of prokaryotic metal sensor proteins. We show here that Zn(II) is the most potent negative allosteric regulator of czr operator/promoter binding in vitro with the trend Zn(II)>Co(II)≫Ni(II), whereas the opposite holds for the binding of NmtR to the nmt operator/promoter, Ni(II)>Co(II)>Zn(II). Characterization of the metal coordination complexes of CzrA and NmtR by UV/visible and x-ray absorption spectroscopies reveals that metals that form four-coordinate tetrahedral complexes with CzrA [Zn(II) and Co(II)] are potent regulators of DNA binding, whereas metals that form five- or six-coordinate complexes with NmtR [Ni(II) and Co(II)] are the strongest allosteric regulators in this system. Strikingly, the Zn(II) coordination complexes of CzrA and NmtR cannot be distinguished from one another by x-ray absorption spectroscopy, with the best fit a His-3-carboxylate complex in both cases. Inspection of the primary structures of CzrA and NmtR, coupled with previous functional data, suggests that three conserved His and one Asp from the C-terminal α5 helix donate ligands to create a four-coordinate complex in both CzrA and NmtR, with NmtR uniquely capable of expanding its coordination number in the Ni(II) and Co(II) complexes by recruiting additional His ligands from a C-terminal extension of the α5 helix

    Clinical factors affecting short- and long-term mortality in older patients with COVID-19: a retrospective cohort study

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    The majority of fatal cases of SARS-CoV-2 was concentrated among older patients. We aimed at assessing risk factors contributing to mortality in this population. A retrospective study including 584 COVID-19 patients aged >= 80 years hospitalized between October 10th 2020 to May 4th 2021 at Ospedale di Circolo (Varese, Italy) and Ospedale Galmarini (Tradate, Italy) was conducted. Evaluation of risk factors associated with in-hospital mortality was the primary endpoint. 509 patients were considered. Median age was 86 [82-89] years. Almost half of the patients (n=241) suffered from >= 3 comorbidities. Overall in-hospital mortality was 39.7% (n=202). Age, chronic kidney disease (CKD), peripheral oxygen saturation at admission, and high-flow oxygen during hospital stay independently predicted in-hospital mortality. Overall mortality at 6 months was 57.8% (n=294) and increased with increasing age and number of comorbidities (P<0.05). Age, CKD, and dementia independently predicted 6-month mortality. Age and comorbidities predicted short- and long-term mortality in older patients (>= 80 years). Stratification of patients according to age and comorbidities might provide critical information for a better management of elderly patients

    Rapid and High-Throughput pan-Orthopoxvirus Detection and Identification using PCR and Mass Spectrometry

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    The genus Orthopoxvirus contains several species of related viruses, including the causative agent of smallpox (Variola virus). In addition to smallpox, several other members of the genus are capable of causing human infection, including monkeypox, cowpox, and other zoonotic rodent-borne poxviruses. Therefore, a single assay that can accurately identify all orthopoxviruses could provide a valuable tool for rapid broad orthopovirus identification. We have developed a pan-Orthopoxvirus assay for identification of all members of the genus based on four PCR reactions targeting Orthopoxvirus DNA and RNA helicase and polymerase genes. The amplicons are detected using electrospray ionization-mass spectrometry (PCR/ESI-MS) on the Ibis T5000 system. We demonstrate that the assay can detect and identify a diverse collection of orthopoxviruses, provide sub-species information and characterize viruses from the blood of rabbitpox infected rabbits. The assay is sensitive at the stochastic limit of PCR and detected virus in blood containing approximately six plaque-forming units per milliliter from a rabbitpox virus-infected rabbit

    Global Surveillance of Emerging Influenza Virus Genotypes by Mass Spectrometry

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    Effective influenza surveillance requires new methods capable of rapid and inexpensive genomic analysis of evolving viral species for pandemic preparedness, to understand the evolution of circulating viral species, and for vaccine strain selection. We have developed one such approach based on previously described broad-range reverse transcription PCR/electrospray ionization mass spectrometry (RT-PCR/ESI-MS) technology.Analysis of base compositions of RT-PCR amplicons from influenza core gene segments (PB1, PB2, PA, M, NS, NP) are used to provide sub-species identification and infer influenza virus H and N subtypes. Using this approach, we detected and correctly identified 92 mammalian and avian influenza isolates, representing 30 different H and N types, including 29 avian H5N1 isolates. Further, direct analysis of 656 human clinical respiratory specimens collected over a seven-year period (1999-2006) showed correct identification of the viral species and subtypes with >97% sensitivity and specificity. Base composition derived clusters inferred from this analysis showed 100% concordance to previously established clades. Ongoing surveillance of samples from the recent influenza virus seasons (2005-2006) showed evidence for emergence and establishment of new genotypes of circulating H3N2 strains worldwide. Mixed viral quasispecies were found in approximately 1% of these recent samples providing a view into viral evolution.Thus, rapid RT-PCR/ESI-MS analysis can be used to simultaneously identify all species of influenza viruses with clade-level resolution, identify mixed viral populations and monitor global spread and emergence of novel viral genotypes. This high-throughput method promises to become an integral component of influenza surveillance
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