Distance follow-up by a remote medical care centre improves adherence to CPAP in patients with obstructive sleep apnoea over the short and long term.

BACKGROUND: Adherence to continuous positive air pressure (CPAP) in patients with obstructive sleep apnoea (OSA) has remained invariably low over the last decades. Remote monitoring of the nocturnal CPAP treatment, within telemedicine (TM)-based follow-up programs, in these patients has been suggested as a potential tool to improve adherence and release the workload of sleep units. The aim of this study was therefore to assess whether a follow-up program carried out by a Remote Medical Care Centre (RMCC), outside the sleep unit, improves adherence to CPAP in the short and long term in patients with OSA. METHODS: In this pilot protocol, we enrolled 37 patients starting CPAP in our Sleep Centre (SC). After three months of standard care in our SC, patients initiated a six-month remote follow-up carried out by the RMCC, functioning as an intermediary between patients and SC. Monthly reports and indication for face-to-face visits were sent to the SC for six months. After this period patients returned to usual care for one year. Results were compared with those obtained in 38 patients (controls) followed with usual care over the same time range. RESULTS: Mean nightly use of CPAP increased from 3.2 ± 2.4 h pre-RMCC to 5.2 ± 1.9 h post-RMCC (p < 0.0001). Nights/month of CPAP use improved from 19.8 ± 9.2 to 25.2 ± 2.5 (p < 0.05) and nights/month with CPAP use >4 h from 12.5 ± 10 to 21.03 ± 8.9 (p < 0.05). This improvement remained stable after 12 months from the return of patients to usual care. No significant changes in CPAP use were observed in controls over the time. CONCLUSION: A six-month follow-up through a remote facility can significantly improve adherence to CPAP in the short and long term. This pilot study provides a solid base for the design of multicentre randomized trials focusing on new models which are able to increase the long-term efficacy of TM programs.

Events Leading to the Establishment of Pregnancy and Placental Formation: The Need to Fine-Tune the Nomenclature on Pregnancy and Gestation.

Today, there is strong and diversified evidence that in humans at least 50% of early embryos do not proceed beyond the pre-implantation period. This evidence comes from clinical investigations, demography, epidemiology, embryology, immunology, and molecular biology. The purpose of this article is to highlight the steps leading to the establishment of pregnancy and placenta formation. These early events document the existence of a clear distinction between embryonic losses during the first two weeks after conception and those occurring during the subsequent months. This review attempts to highlight the nature of the maternal-embryonic dialogue and the major mechanisms active during the pre-implantation period aimed at "selecting" embryos with the ability to proceed to the formation of the placenta and therefore to the completion of pregnancy. This intense molecular cross-talk between the early embryo and the endometrium starts even before the blastocyst reaches the uterine cavity, substantially initiating and conditioning the process of implantation and the formation of the placenta. Today, several factors involved in this dialogue have been identified, although the best-known and overall, the most important, still remains Chorionic Gonadotrophin, indispensable during the first 8 to 10 weeks after fertilization. In addition, there are other substances acting during the first days following fertilization, the Early Pregnancy Factor, believed to be involved in the suppression of the maternal response, thereby allowing the continued viability of the early embryo. The Pre-Implantation Factor, secreted between 2 and 4 days after fertilization. This linear peptide molecule exhibits a self-protective and antitoxic action, is present in maternal blood as early as 7 days after conception, and is absent in the presence of non-viable embryos. The Embryo-Derived Platelet-activating Factor, produced and released by embryos of all mammalian species studied seems to have a role in the ligand-mediated trophic support of the early embryo. The implantation process is also guided by signals from cells in the decidualized endometrium. Various types of cells are involved, among them epithelial, stromal, and trophoblastic, producing a number of cellular molecules, such as cytokines, chemokines, growth factors, and adhesion molecules. Immune cells are also involved, mainly uterine natural killer cells, macrophages, and T cells. In conclusion, events taking place during the first two weeks after fertilization determine whether pregnancy can proceed and therefore whether placenta's formation can proceed. These events represent the scientific basis for a clear distinction between the first two weeks following fertilization and the rest of gestation. For this reason, we propose that a new nomenclature be adopted specifically separating the two periods. In other words, the period from fertilization and birth should be named "gestation", whereas that from the completion of the process of implantation leading to the formation of the placenta, and birth should be named "pregnancy".

Hypometabolism, Alzheimer's Disease, and Possible Therapeutic Targets: An Overview.

The brain is a highly dynamic organ that requires a constant energy source to function normally. This energy is mostly supplied by glucose, a simple sugar that serves as the brain's principal fuel source. Glucose transport across the blood-brain barrier (BBB) is primarily controlled via sodium-independent facilitated glucose transport, such as by glucose transporter 1 (GLUT1) and 3 (GLUT3). However, other glucose transporters, including GLUT4 and the sodium-dependent transporters SGLT1 and SGLT6, have been reported in vitro and in vivo. When the BBB endothelial layer is crossed, neurons and astrocytes can absorb the glucose using their GLUT1 and GLUT3 transporters. Glucose then enters the glycolytic pathway and is metabolized into adenosine triphosphate (ATP), which supplies the energy to support cellular functions. The transport and metabolism of glucose in the brain are impacted by several medical conditions, which can cause neurological and neuropsychiatric symptoms. Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy, traumatic brain injury (TBI), schizophrenia, etc., are a few of the most prevalent disorders, characterized by a decline in brain metabolism or hypometabolism early in the course of the disease. Indeed, AD is considered a metabolic disorder related to decreased brain glucose metabolism, involving brain insulin resistance and age-dependent mitochondrial dysfunction. Although the conventional view is that reduced cerebral metabolism is an effect of neuronal loss and consequent brain atrophy, a growing body of evidence points to the opposite, where hypometabolism is prodromal or at least precedes the onset of brain atrophy and the manifestation of clinical symptoms. The underlying processes responsible for these glucose transport and metabolic abnormalities are complicated and remain poorly understood. This review article provides a comprehensive overview of the current understanding of hypometabolism in AD and potential therapeutic targets.

Exposure to Stress Alters Cardiac Gene Expression and Exacerbates Myocardial Ischemic Injury in the Female Murine Heart.

Mental stress is a risk factor for myocardial infarction in women. The central hypothesis of this study is that restraint stress induces sex-specific changes in gene expression in the heart, which leads to an intensified response to ischemia/reperfusion injury due to the development of a pro-oxidative environment in female hearts. We challenged male and female C57BL/6 mice in a restraint stress model to mimic the effects of mental stress. Exposure to restraint stress led to sex differences in the expression of genes involved in cardiac hypertrophy, inflammation, and iron-dependent cell death (ferroptosis). Among those genes, we identified tumor protein p53 and cyclin-dependent kinase inhibitor 1A (p21), which have established controversial roles in ferroptosis. The exacerbated response to I/R injury in restraint-stressed females correlated with downregulation of p53 and nuclear factor erythroid 2-related factor 2 (Nrf2, a master regulator of the antioxidant response system-ARE). S-female hearts also showed increased superoxide levels, lipid peroxidation, and prostaglandin-endoperoxide synthase 2 (Ptgs2) expression (a hallmark of ferroptosis) compared with those of their male counterparts. Our study is the first to test the sex-specific impact of restraint stress on the heart in the setting of I/R and its outcome.

An update on lateral flow immunoassay for the rapid detection of SARS-CoV-2 antibodies.

Over the last three years, after the outbreak of the COVID-19 pandemic, an unprecedented number of novel diagnostic tests have been developed. Assays to evaluate the immune response to SARS-CoV-2 have been widely considered as part of the control strategy. The lateral flow immunoassay (LFIA), to detect both IgM and IgG against SARS-CoV-2, has been widely studied as a point-of-care (POC) test. Compared to laboratory tests, LFIAs are faster, cheaper and user-friendly, thus available also in areas with low economic resources. Soon after the onset of the pandemic, numerous kits for rapid antibody detection were put on the market with an emergency use authorization. However, since then, scientists have tried to better define the accuracy of these tests and their usefulness in different contexts. In fact, while during the first phase of the pandemic LFIAs for antibody detection were auxiliary to molecular tests for the diagnosis of COVID-19, successively these tests became a tool of seroprevalence surveillance to address infection control policies. When in 2021 a massive vaccination campaign was implemented worldwide, the interest in LFIA reemerged due to the need to establish the extent and the longevity of immunization in the vaccinated population and to establish priorities to guide health policies in low-income countries with limited access to vaccines. Here, we summarize the accuracy, the advantages and limits of LFIAs as POC tests for antibody detection, highlighting the efforts that have been made to improve this technology over the last few years.

Use of Conventional Cigarette Smoking and E-Cigarette Vaping for Experimental Stroke Studies in Mice.

Cigarette smoking is a major prodromal factor for the onset of many adverse health effects that may occur in the short run and is the leading cause of preventable disease, disability, and death in the United States. Moreover, it is well established that chronic smoking is associated with vascular endothelial dysfunction in a causative and dose-dependent manner primarily related to the release of reactive oxygen species (ROS), nicotine, and the induction of oxidative stress (OS)-driven inflammation. Preclinical studies have also shown that nicotine (the principal e-liquid ingredient used in e-cigarettes) can also cause OS, exacerbating cerebral ischemia and secondary brain injury. Likewise, chronic e-Cig vaping could be prodromal to cerebrovascular impairment and promote cerebrovascular conditions favoring stroke onset and worsening post-ischemic brain injury. Therefore, using mouse models is crucial to understand how xenobiotics such as those released by conventional and/or e-cigs can impact the onset and severity of stroke as well as post-stroke recovery. To appropriately model human-like smoking/vaping behavior in mice, however, the exposure to these xenobiotics must be standardized and undertaken in a controlled environment. This chapter describes a well-validated protocol to reproduce standardized chronic tobacco smoke or e-cigarette vape exposure in mice in the setting of a mouse transient ischemic stroke model.

Cosmogenic radionuclides in the Cavezzo meteorite: Gamma-ray measurement and detection efficiency simulations.

The Cavezzo meteorite was recovered on January 4th, 2020, just three days after the fall observed over Northern Italy by the all-sky cameras of the Italian PRISMA fireball network. Two specimens, weighing 3.1 g (F1) and 52.2 g (F2), were collected in the predicted strewn-field and the meteorite has been classified as an L5 anomalous chondrite. The gamma-activity of the F2 sample was measured at the Monte dei Cappuccini underground Research Station (Torino, Italy) with a large-volume HPGe-NaI(Tl) spectrometer. Thanks to the high efficiency, selectivity, and low background of the spectrometer, we were able to detect fifteen cosmogenic radioisotopes. The presence of nuclides with half-lives down to a few days (47Ca, 52Mn, and 48V) undoubtedly confirmed the recent fall of the sample. The very low activity of 44Ti and 60Co was revealed with a particular coincidence between the HPGe and NaI(Tl) detectors. To obtain the detection efficiency, we have simulated the response of the detector with the GEANT4 toolkit, once the spectrometer's dead layer thickness was estimated using standards of known activity. Moreover, the simulation of the Dhajala meteorite (H3/4 chondrite) measurement allowed us to verify that the self-absorption of the sample is correctly taken into account and validate our simulations. In this contribution, we focus on the coincidence optimization techniques and the detection efficiency computation.

Nocturnal nasal high-flow oxygen therapy in elderly patients with concomitant chronic obstructive pulmonary disease and obstructive sleep apnea.

PURPOSE: The coexistence of obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) is known as "overlap syndrome" (OS). Patients with OS are usually older than patients with OSA alone, suffer from more profound oxygen desaturation during the obstructive events often accompanied by sustained nocturnal hypoventilation. Although oxygen-enriched positive airway pressure (PAP) is the treatment of choice in these patients, this therapy is often poorly tolerated particularly by the elderly. The aim of this study was to assess the usefulness of nocturnal oxygen therapy via nasal high flow (NHF-OT) as a possible alternative to PAP in patients with OS. METHODS: Patients > 65 years old with OS and nocturnal respiratory failure (time spent below SaO2 90% (T90) > 30%) had cardio-respiratory monitoring performed at baseline, during NHF-OT, or during conventional oxygen therapy (COT). RESULTS: A total of 40 patients were enrolled in the study. NHF-OT significantly reduced the apnea-hypopnea index (AHI) in all patients compared to baseline and COT. The mean basal AHI was 25.4 ± 8.6. During COT and NHF-OT, the AHI was 19.4 ± 7 and 5.4 ± 4.6, respectively (P < 0.001) and 19 patients reached an AHI < 5 during NHF-OT. The mean nocturnal SaO2% was 86.2 ± 2.6 at baseline and at equivalent FiO2 it significantly increased to 91.8 ± 2.4 during COT and to 93.9 ± 2.5 during NHF-OT (P < 0.001). The T90% was 48.7 ± 20.1 at baseline, 16.8 ± 11.7 during COT, and 8.8 ± 8.0 during NHF-OT (P < 0.001). CONCLUSIONS: In elderly patients with OS, nocturnal treatment with NHF-OT significantly reduces obstructive episodes and improves oxygenation. As the treatment is generally well tolerated compared to PAP, NHF-OT may be a possible alternative therapy in this subgroup of patients.

Genetic and Survey Data Improves Performance of Machine Learning Model for Long COVID.

Over 200 million SARS-CoV-2 patients have or will develop persistent symptoms (long COVID). Given this pressing research priority, the National COVID Cohort Collaborative (N3C) developed a machine learning model using only electronic health record data to identify potential patients with long COVID. We hypothesized that additional data from health surveys, mobile devices, and genotypes could improve prediction ability. In a cohort of SARS-CoV-2 infected individuals (n=17,755) in the All of Us program, we applied and expanded upon the N3C long COVID prediction model, testing machine learning infrastructures, assessing model performance, and identifying factors that contributed most to the prediction models. For the survey/mobile device information and genetic data, extreme gradient boosting and a convolutional neural network delivered the best performance for predicting long COVID, respectively. Combined survey, genetic, and mobile data increased specificity and the Area Under Curve the Receiver Operating Characteristic score versus the original N3C model.

Sleep quality and mental health during the COVID-19 pandemic in patients with severe obstructive sleep apnea.

BACKGROUND: The first wave of the COVID-19 pandemic has produced remarkable effects on the sleep quality and mental status of the general population and more dramatic effects on patients with chronic illness. Patients with obstructive sleep apnea (OSA), already suffering from disordered sleep, might be more susceptible to the effect of the pandemic on their sleep quality and mental health. We therefore performed a case-control study to compare sleep quality, depression and anxiety symptoms reported by patients with severe OSA and age-matched healthy subjects during the first wave of the COVID-19. In June-July 2020 we enrolled a total of 222 patients with severe OSA, all treated with continuous positive airway pressure, and 164 healthy controls. Self-reported sleep quality was assessed using the Pittsburg Sleep Quality Index (PSQI). Symptoms of depression were assessed using the Patient Health Questionnaire module 9 (PHQ-9), while the specific "Coronavirus Anxiety Scale" (CAS) evaluated the level of anxiety. RESULTS: Patients with OSA (61% males, 65 ± 9.6 years old, BMI 30.5 ± 3.6) and healthy controls had similar characteristics except for BMI slightly lower in controls. The perceived quality of sleep, referred to the pre-pandemic period, was significantly worse in patients with OSA than in controls. During the pandemic the rate of reported sleep disturbance increased from 54 to 66% in patients with OSA and from 29 to 40% in controls. A high percentage of patients and controls reported symptoms of depression (61% OSA and 65% controls), whereas lower levels of anxiety, similar in the two groups, were observed. In patients with OSA the PSQI score significantly positively correlated with the PHQ-9 score (r2 = 0.81) and the CAS score (r2 = 0.65). CONCLUSION: The rate of reported sleep disturbance in patients with OSA during the first wave of the COVID-19 pandemic is one of the highest evidenced in literature so far. As for the general population, in these patients there is a strict link between the perceived sleep quality and the psychological distress caused by the pandemic. A further deterioration of sleep quality is a fearsome event in the life of these patients who face life-long sleep problems.

Molecular Mechanisms of Multi-Organ Failure in COVID-19 and Potential of Stem Cell Therapy.

As the number of confirmed cases and deaths occurring from Coronavirus disease 2019 (COVID-19) surges worldwide, health experts are striving hard to fully comprehend the extent of damage caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although COVID-19 primarily manifests itself in the form of severe respiratory distress, it is also known to cause systemic damage to almost all major organs and organ systems within the body. In this review, we discuss the molecular mechanisms leading to multi-organ failure seen in COVID-19 patients. We also examine the potential of stem cell therapy in treating COVID-19 multi-organ failure cases.

Long-Term Consequences of Placental Vascular Pathology on the Maternal and Offspring Cardiovascular Systems.

Over the last thirty years, evidence has been accumulating that Hypertensive Disorders of Pregnancy (HDP) and, specifically, Preeclampsia (PE) produce not only long-term effects on the pregnant woman, but have also lasting consequences for the fetus. At the core of these consequences is the phenomenon known as defective deep placentation, being present in virtually every major obstetrical syndrome. The profound placental vascular lesions characteristic of this pathology can induce long-term adverse consequences for the pregnant woman's entire arterial system. In addition, placental growth restriction and function can, in turn, cause a decreased blood supply to the fetus, with long-lasting effects. Women with a history of HDP have an increased risk of Cardiovascular Diseases (CVD) compared with women with normal pregnancies. Specifically, these subjects are at a future higher risk of: Hypertension; Coronary artery disease; Heart failure; Peripheral vascular disease; Cerebrovascular accidents (Stroke); CVD-related mortality. Vascular pathology in pregnancy and CVD may share a common etiology and may have common risk factors, which are unmasked by the "stress" of pregnancy. It is also possible that the future occurrence of a CVD may be the consequence of endothelial dysfunction generated by pregnancy-induced hypertension that persists after delivery. Although biochemical and biophysical markers of PE abound, information on markers for a comparative evaluation in the various groups is still lacking. Long-term consequences for the fetus are an integral part of the theory of a fetal origin of a number of adult diseases, known as the Barker hypothesis. Indeed, intrauterine malnutrition and fetal growth restriction represent significant risk factors for the development of chronic hypertension, diabetes, stroke and death from coronary artery disease in adults. Other factors will also influence the development later in life of hypertension, coronary and myocardial disease; they include parental genetic disposition, epigenetic modifications, endothelial dysfunction, concurrent intrauterine exposures, and the lifestyle of the affected individual.

Misdiagnosis of asthma and COPD and underuse of spirometry in primary care unselected patients.

BACKGROUND: The diagnosis of both asthma and chronic obstructive pulmonary disease (COPD) consists of a combination of classical symptoms and signs, and the evidence of consistent lung function abnormalities. Spiromety has been reported to be underused, possibly for practical difficulties in accessing to a lung function lab. This may lead to misdiagnosis of both asthma and COPD. We aimed to evaluate the frequency of spirometry use and the concordance between doctor-diagnosed asthma and COPD and spirometric patterns, in an unselected cohort of patients sent by general practitioners to perform a spirometry. METHODS: The first 300 patients consecutively enrolled patients performed spirometry and bronchodilator test with salbutamol 400 mcg. Demographic, clinical and lung function data have been collected. RESULTS: 128 patients (42.7%) declared a doctor-diagnosed asthma and 75 (25%) a doctor-diagnosis of COPD; the remaining subjects never had received any respiratory diagnosis. Only 112 patients with doctor-diagnosed asthma (55.2%) and 114 (56.2%) with doctor-diagnosed COPD have ever performed a spirometry in their entire life (average time since the last spirometry was about 47.0 months). Eighty-nine (69.5%) and 10 (13.3%) patients with respectively doctor-diagnosed asthma and COPD had concordant spirometric patterns with their known diseases. DISCUSSION: we described a worrying lack of use of spirometry and a high proportion of misdiagnosis, in patients with suspect chronic airway inflammatory diseases and cared by primary care physicians. Novel strategies to overcome this situation include should be implemented to give a better care to our patients.

A foraminiferal δ(18)O record covering the last 2,200 years.

Thanks to the precise core dating and the high sedimentation rate of the drilling site (Gallipoli Terrace, Ionian Sea) we were able to measure a foraminiferal δ(18)O series covering the last 2,200 years with a time resolution shorter than 4 years. In order to support the quality of this data-set we link the δ(18)O values measured in the foraminifera shells to temperature and salinity measurements available for the last thirty years covered by the core. Moreover, we describe in detail the dating procedures based on the presence of volcanic markers along the core and on the measurement of (210)Pb and (137)Cs activity in the most recent sediment layers. The high time resolution allows for detecting a δ(18)O decennial-scale oscillation, together with centennial and multicentennial components. Due to the dependence of foraminiferal δ(18)O on environmental conditions, these oscillations can provide information about temperature and salinity variations in past millennia. The strategic location of the drilling area makes this record a unique tool for climate and oceanographic studies of the Central Mediterranean.

Marine Sediments Remotely Unveil Long-Term Climatic Variability Over Northern Italy.

A deep understanding of natural decadal variability is pivotal to discuss recently observed climate trends. Paleoclimate proxies allow reconstructing natural variations before the instrumental period. Typically, regional-scale reconstructions depend on factors like dating, multi-proxy weighting and calibration, which may lead to non-robust reconstructions. Riverine records inherently integrate information about regional climate variability, partly overcoming the above mentioned limitation. The Po River provides major freshwater input to Eastern Mediterranean, as its catchment encompasses a large part of Northern Italy. Here, using historical discharge data and oceanographic measurements, we show that Po River discharge undergo robust decadal fluctuations that reach the Ionian Sea, ~1,000 km South of Po River delta, through propagating salinity anomalies. Based on this propagation, we use a high-resolution foraminiferal δ(18)O record from a sediment core in the Ionian Sea to reconstruct North Italian hydrological variability on millennial-scale for the first time. The reconstruction reveals highly significant decadal variability that persists over the last 2,000 years. Many reconstructed extremes correspond to documented catastrophic events. Our study provides the first millennial-scale reconstruction of the strength of decadal hydrological variability over Northern Italy. It paves the way to assess the persistence of large-scale circulation fingerprints on the North Italian climate.

Psoriatic patients have an increased risk of polycystic ovary syndrome: results of a cross-sectional analysis.

OBJECTIVE: To define the prevalence and the features of polycystic ovary syndrome (PCOS) in patients with psoriasis. To our knowledge, the association between PCOS and psoriasis has not been explored in previous studies. Psoriasis is linked with metabolic syndrome, insulin resistance, and non-alcoholic fatty liver disease, which are features often associated with PCOS. DESIGN: A cross-sectional analysis was performed between January 2010 and April 2012. SETTING: Unit of human reproductive pathophysiology, Catholic University Hospital. PATIENT(S): We prospectively analyzed 51 patients with psoriasis and 102 healthy age- and body mass index (BMI)-matched controls. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The prevalence and characteristics of PCOS women of reproductive age with chronic plaque psoriasis. RESULT(S): The prevalence of PCOS was greater in patients with psoriasis than in matched control subjects (47.05% and 11.76%, respectively; odds ratio, 6.66; 95% confidence interval 2.95-15.07). Among the women with psoriasis, the prevalence of Psoriasis Area and Severity Index ≥10 was higher in patients with PCOS than in subjects without PCOS (odds ratio, 3.5; 95% confidence interval 1.04-11.72). CONCLUSION(S): The prevalence of PCOS in women with psoriasis is remarkably greater than in age- and BMI-matched control women.

Influence of projection effects on the observed differential rotation rate in the UV corona.

Following previous investigations by Giordano and Mancuso [1] and Mancuso and Giordano [2,3] on the differential rotation of the solar corona as obtained through the analysis of the intensity time series of the O VI 1032 Å spectral line observed by the UVCS/SOHO telescope during solar cycle 23, we analysed the possible influence of projection effects of extended coronal structures on the observed differential rotation rate in the ultraviolet corona. Through a simple geometrical model, we found that, especially at higher latitudes, the differential rotation may be less rigid than observed, since features at higher latitudes could be actually linked to much lower coronal structures due to projection effects. At solar maximum, the latitudinal rigidity of the UV corona, with respect to the differential rotating photosphere, has thus to be considered as an upper limit of the possible rigidity. At solar minimum and near the equatorial region throughout the solar cycle, projection effects are negligible.

Super- and sub-critical regions in shocks driven by radio-loud and radio-quiet CMEs.

White-light coronagraphic images of Coronal Mass Ejections (CMEs) observed by SOHO/LASCO C2 have been used to estimate the density jump along the whole front of two CME-driven shocks. The two events are different in that the first one was a "radio-loud" fast CME, while the second one was a "radio quiet" slow CME. From the compression ratios inferred along the shock fronts, we estimated the Alfvén Mach numbers for the general case of an oblique shock. It turns out that the "radio-loud" CME shock is initially super-critical around the shock center, while later on the whole shock becomes sub-critical. On the contrary, the shock associated with the "radio-quiet" CME is sub-critical at all times. This suggests that CME-driven shocks could be efficient particle accelerators at the shock nose only at the initiation phases of the event, if and when the shock is super-critical, while at later times they lose their energy and the capability to accelerate high energetic particles.