Hardware prototyping and validation of a W-ΔDOR digital signal processor

Microwave tracking, usually performed by on ground processing of the signals coming from a spacecraft, represents a crucial aspect in every deep-space mission. Various noise sources, including receiver noise, affect these signals, limiting the accuracy of the radiometric measurements obtained from the radio link. There are several methods used for spacecraft tracking, including the Delta-Differential One-Way Ranging (ΔDOR) technique. In the past years, European Space Agency (ESA) missions relied on a narrowband ΔDOR system for navigation in the cruise phase. To limit the adverse effect of nonlinearities in the receiving chain, an innovative wideband approach to ΔDOR measurements has recently been proposed. This work presents the hardware implementation of a new version of the ESA X/Ka Deep Space Transponder based on the new tracking technique named Wideband ΔDOR (W-ΔDOR). The architecture of the new transponder guarantees backward compatibility with narrowband ΔDOR

Antiphospholipid antibodies in patients with stroke during COVID-19: A role in the signaling pathway leading to platelet activation

Background: Several viral and bacterial infections, including COVID-19, may lead to both thrombotic and hemorrhagic complications. Previously, it has been demonstrated an "in vitro " pathogenic effect of "antiphospholipid " antibodies (aPLs), which are able to activate a proinflammatory and procoagulant phenotype in monocytes, endothelial cells and platelets. This study analyzed the occurrence of aPL IgG in patients with acute ischemic stroke (AIS) during COVID-19, evaluating the effect of Ig fractions from these patients on signaling and functional activation of platelets. Materials and methods: Sera from 10 patients with AIS during COVID-19, 10 non-COVID-19 stroke patients, 20 COVID-19 and 30 healthy donors (HD) were analyzed for anti-cardiolipin, anti-beta 2-GPI, anti-phosphatidylserine/prothrombin and anti-vimentin/CL antibodies by ELISA. Platelets from healthy donors were incubated with Ig fractions from these patients or with polyclonal anti-beta 2-GPI IgG and analyzed for phospho-ERK and phospho-p38 by western blot. Platelet secretion by ATP release dosage was also evaluated. Results: We demonstrated the presence of aPLs IgG in sera of patients with AIS during COVID-19. Treatment with the Ig fractions from these patients or with polyclonal anti-beta 2-GPI IgG induced a significant increase of phospho-ERK and phospho-p38 expression. In the same vein, platelet activation was supported by the increase of adenyl nucleotides release induced by Ig fractions. Conclusions: This study demonstrates the presence of aPLs in a subgroup of COVID-19 patients who presented AIS, suggesting a role in the mechanisms contributing to hypercoagulable state in these patients. Detecting these antibodies as a serological marker to check and monitor COVID-19 may contribute to improve the risk stratification of thromboembolic manifestations in these patients

SARS-CoV-2 infection predicts larger infarct volume in patients with acute ischemic stroke

Background and purpose: Acute ischemic stroke (AIS) is a fearful complication of Coronavirus Disease-2019 (COVID-19). Aims of this study were to compare clinical/radiological characteristics, endothelial and coagulation dysfunction between acute ischemic stroke (AIS) patients with and without COVID-19 and to investigate if and how the SARS-CoV-2 spike protein (SP) was implicated in triggering platelet activation. Methods: We enrolled AIS patients with COVID-19 within 12 h from onset and compared them with an age- and sex-matched cohort of AIS controls without COVID-19. Neuroimaging studies were performed within 24 h. Blood samples were collected in a subset of 10 patients. Results: Of 39 AIS patients, 22 had COVID-19 and 17 did not. Admission levels of Factor VIII and von Willebrand factor antigen were significantly higher in COVID-19 patients and positively correlated with the infarct volume. In multivariate linear regression analyses, COVID-19 was an independent predictor of infarct volume (B 20.318, Beta 0.576, 95%CI 6.077-34.559; p = 0.011). SP was found in serum of 2 of the 10 examined COVID-19 patients. Platelets from healthy donors showed a similar degree of procoagulant activation induced by COVID-19 and non-COVID-19 patients' sera. The anti-SP and anti-FcγRIIA blocking antibodies had no effect in modulating platelet activity in both groups. Conclusions: SARS-CoV-2 infection seems to play a major role in endothelium activation and infarct volume extension during AIS

'Aspirin resistance' or treatment non-compliance: Which is to blame for cardiovascular complications?

Aspirin is one of the 'cornerstone' drugs in our current management of cardiovascular disorders. However, despite the prescription of aspirin recurrent vascular events still occur in 10–20% of patients. These, data together with the observations of diminished antiaggregatory response to aspirin in some subjects have provided the basis of the current debate on the existence of so-called "aspirin resistance". Unfortunately, many of the tests employed to define 'aspirin resistance' lack sufficient sensitivity, specificity, and reproducibility. The prevalence of 'aspirin resistance' as defined by each test varies widely, and furthermore, the value of a single point estimate measure of aspirin resistance is questionable. The rate of 'aspirin resistance' is law if patients observed to ingest aspirin, with large proportion of patients to be pseudo-'aspirin resistant', due to non-compliance. What are the implications for clinical practice? Possible non-adherence to aspirin prescription should also be carefully considered before changing to higher aspirin doses, other antiplatelet drugs (e.g. clopidogrel) or even combination antiplatelet drug therapy. Given the multifactorial nature of atherothrombotic disease, it is not surprising that only about 25% of all cardiovascular complications can usually be prevented by any single medication. We would advocate against routine testing of platelet sensitivity to aspirin (as an attempt to look for 'aspirin resistance') but rather, to highlight the importance of clinicians and public attention to the problem of treatment non-compliance

Parathyroidectomy and survival in a cohort of Italian dialysis patients: results of a multicenter, observational, prospective study

Background: Severe secondary hyperparathyroidism (SHPT) is associated with mortality in end stage kidney disease (ESKD). Parathyroidectomy (PTX) becomes necessary when medical therapy fails, thus highlighting the interest to compare biochemical and clinical outcomes of patients receiving either medical treatment or surgery. Methods: We aimed to compare overall survival and biochemical control of hemodialysis patients with severe hyperparathyroidism, treated by surgery or medical therapy followed-up for 36 months. Inclusion criteria were age older than 18 years, renal failure requiring dialysis treatment (hemodialysis or peritoneal dialysis) and ability to sign the consent form. A control group of 418 patients treated in the same centers, who did not undergo parathyroidectomy was selected after matching for age, sex, and dialysis vintage. Results: From 82 Dialysis units in Italy, we prospectively collected data of 257 prevalent patients who underwent parathyroidectomy (age 58.2 ± 12.8 years; M/F: 44%/56%, dialysis vintage: 15.5 ± 8.4 years) and of 418 control patients who did not undergo parathyroidectomy (age 60.3 ± 14.4 years; M/F 44%/56%; dialysis vintage 11.2 ± 7.6 y). The survival rate was higher in the group that underwent parathyroidectomy (Kaplan–Meier log rank test = 0.002). Univariable analysis (HR 0.556, CI: 0.387–0.800, p = 0.002) and multivariable analysis (HR 0.671, CI:0.465–0.970, p = 0.034), identified parathyroidectomy as a protective factor of overall survival. The prevalence of patients at KDOQI targets for PTH was lower in patients who underwent parathyroidectomy compared to controls (PTX vs non-PTX: PTH < 150 pg/ml: 59% vs 21%, p = 0.001; PTH at target: 18% vs 37% p = 0.001; PTH > 300 pg/ml 23% vs 42% p = 0.001). The control group received more intensive medical treatment with higher prevalence of vitamin D (65% vs 41%, p = 0.0001), calcimimetics (34% vs 14%, p = 0.0001) and phosphate binders (77% vs 66%, p = 0.002). Conclusions: Our data suggest that parathyroidectomy is associated with survival rate at 36 months, independently of biochemical control. Lower exposure to high PTH levels could represent an advantage in the long term. Graphical abstract: [Figure not available: see fulltext.]

Dual Antiplatelet Therapy in Neuroendovascular Procedures

Dual antiplatelet therapy is currently used in clinical practice to prevent thrombotic events during and after neuroendovascular procedures. </p><p> Despite antiplatelet therapy, a significant number of patients show insufficient platelet inhibition, as measured by laboratory tests. These patients are at greater risk of developing thrombotic events than are patients sensitive to the treatment. This phenomenon is known as "antiplatelet drug resistance". The mechanisms that influence the individual response to antiplatelet therapy are not completely understood and are likely to be multifactorial. </p><p> Several platelet function tests have been developed to monitor antiplatelet therapy and may assist in adjusting it to improve outcomes in patients with antiplatelet drug resistance. Nevertheless, the optimal management for these patients has not yet been established. This chapter summarizes information on the available antiplatelet drugs currently used in neuroendovascular procedures, the commonly used tools for platelet function testing and the potential mechanisms underlying suboptimal platelet inhibition by aspirin and clopidogrel

Transparent and conductive ZnO : Al thin films prepared by sol-gel dip-coating

Aluminum doped zinc oxide polycrystalline thin films (AZO) were prepared by sol-gel dip-coating process. The sol was prepared from an ethanolic solution of zinc acetate using lithium hydroxide or succinic acid as hydrolytic catalyst. The quantity of aluminum in the sol was varied from 1 to 10 mol%. The structural characteristics studied by X-ray diffractometry were complemented by resistivity measurements and UV-Vis-NIR spectroscopy. The films are transparent from the near ultraviolet to the near infrared, presenting an absorption cut-off at almost 290 nm, irrespective of the nature of the catalyst and doping level. The best conductors were obtained for the AZO films containing 3 mol% of aluminum, prepared under acidic and basic catalysis and sintered at 450 degreesC. Their optical band-gap of 4.4 eV calculated from the absorption cut-off is larger than the values for band-gap widening predicted by the standard model for polar semiconductors. These polycrystalline films are textured with preferential orientation of grains along the wurtzite c-axis or the (100) direction. (C) 2003 Elsevier Ltd. All rights reserved