Cardiac hypertrophy and heart failure: from the case to review of literature

In response to an increased workload due to physiological or pathological stimuli, the heart may undergo a process of growth with increased muscle mass called cardiac hypertrophy. It is a particular mechanism of long term compensation used by the heart to adapt permanently to a greater workload. Although, through its peculiar structural, molecular and metabolic characteristics, in early stage the hypertrophy allows to maintain an adequate cardiac function, after a variable period of time, the same characteristics promote the evolution to contractile dysfunction and heart failure. The latter represents an important cause of death and so the cardiac hypertrophy increases the cardiovascular morbidity and mortality. In this paper we report a rare case of extremely high degree of concentric cardiac hypertrophy, with a heart weight of 1050 g and longitudinal diameter of 16.5 cm, transverse diameter of 16 cm and antero-posterior diameter of 9 cm. The thickness of the left ventricle free wall was 4.2 cm, of the septum 4.3 cm and at the apex level 3.5 cm. These data, compared with those described in scientific literature, indicate the exceptional nature of our necropsy finding of a huge cardiac hypertrophy. The analysis of the pathogenetic mechanisms, which may determinate the fatal event in case of cardiac hypertrophy, shows that in the described case the death cause can be the onset of heart failure in presence of cardiomegaly

Year in review: Critical Care 2004 – nephrology

We summarize all original research in the field of critical care nephrology published in 2004 or accepted for publication in Critical Care and, when considered relevant or directly linked to this research, in other journals. Articles were grouped into four categories to facilitate a rapid overview. First, regarding the definition of acute renal failure (ARF), the RIFLE criteria (risk, injury, failure, loss, ESKD [end-stage kidney disease]) for diagnosis of ARF were defined by the Acute Dialysis Quality Initiative workgroup and applied in clinical practice by some authors. The second category is acid–base disorders in ARF; the Stewart–Figge quantitative approach to acidosis in critically ill patients has been utilized by two groups of researchers, with similar results but different conclusions. In the third category – blood markers during ARF – cystatin C as an early marker of ARF and procalcitonin as a sepsis marker during continuous venovenous haemofiltration were examined. Finally, in the extracorporeal treatment of ARF, the ability of two types of high cutoff haemofilters to influence blood levels of middle- and high-molecular-weight toxins showed promise

Year in review 2005: Critical Care – nephrology

We summarize original research in the field of critical care nephrology accepted or published in 2005 in Critical Care and, when considered relevant or directly linked to this research, in other journals. The articles have been grouped into four categories to facilitate a rapid overview. First, physiopathology, epidemiology and prognosis of acute renal failure (ARF): an extensive review and some observational studies have been performed with the aim of describing aspects of ARF physiopathology, precise epidemiology and long-term outcomes. Second, several authors have performed clinical trials utilizing a potential nephro-protective drug, fenoldopam, with different results. Third, the issue of continuous renal replacement therapies dose has been addressed in a small prospective study and a large observational trial. And fourth, alternative indications to extracorporeal treatment of ARF and systemic inflammatory response syndrome have been explored by three original clinical studies

Year in review 2007: Critical Care – nephrology

We summarize original research in the field of critical care nephrology that was accepted for publication or published in 2007 in Critical Care and, when considered relevant or directly linked to this research, in other journals. Four main topics were identified for a brief overview. The first of these was the definition of acute kidney injury and recent evidence showing the validity of RIFLE (Risk, Injury, Failure, Loss and End-stage kidney disease) criteria and the recent Acute Kidney Injury Network review of the same criteria. Second, we cover the clinical and experimental utilization of novel biomarkers for diagnosis of acute kidney injury, giving special attention to neutrophil gelatinase-associated lipocalin protein. The third area selected for review is outcomes of acute kidney injury during the past 10 years, described by a recent Austrailian epidemiological study. Finally, specific technical features of renal replacement therapies were examined in 2007, specifically regarding anticoagulation and vascular access

Ray-tracing simulations and spectral models of X-ray radiation in dusty media

Dust can play an important role in shaping the X-ray spectra and images of astrophysical sources. In this work we report on the implementation of dust in the ray-tracing platform RefleX. We illustrate the different effects associated to the interaction between X-ray photons and dust grains, such as dust scattering, near-edge X-ray absorption fine structures and shielding. We show how the cross-sections of the photon-gas interaction change depending on the fraction of metals in dust grains (i.e. the dust depletion factor). We compare RefleX simulations to the most widely-used absorption model that includes dust, and show how X-ray spectra are affected by the presence of dust in the absorbing/reprocessing medium for different geometries. We also show how RefleX can be used to reproduce the dust scattering halos observed in Galactic sources, and release the first torus X-ray spectral model that considers dust absorption and scattering (RXTorusD), to reproduce the spectra of active galactic nuclei (AGN). RXTorusD also considers other physical process that are not included in the most widely-used AGN torus models, such as Rayleigh scattering and scattering on molecular gas, which can lead to remarkable differences in the predicted X-ray spectra for the same set of geometrical and physical parameters.Comment: ApJ in press. The RXTorusD model will be available once the the paper will be published, while RefleXv3.0 can be found here: https://www.astro.unige.ch/refle

Shedding Light on the Compton-thick Active Galactic Nucleus in the Ultra-luminous Infrared Galaxy UGC 5101 with Broadband X-ray Spectroscopy

We report the broadband X-ray spectra of the ultra-luminous infrared galaxy (ULIRG) UGC 5101 in the 0.25-100 keV band observed with Swift/Burst Alert Telescope (BAT), NuSTAR, Suzaku, XMM-Newton, and Chandra. A Compton-thick AGN obscured with a hydrogen column density of $\approx 1.3\times10^{24}$ cm$^{-2}$ is detected above 10 keV. A spectral fit with a numerical torus model favors a large half opening angle of the torus, $>41$ degrees, suggesting that the covering fraction of material heavily obscuring the X-ray source is moderate. The intrinsic 2-10 keV luminosity is determined to be $\approx 1.4\times 10^{43}$ erg s$^{-1}$, which is $\approx$2.5 times larger than the previous estimate using only data below 10 keV with a simple spectral model. We find that UGC 5101 shows the ratio between the [O IV] 26 $\mu$m line and 2-10 keV luminosities similar to those of normal Seyfert galaxies, along with other ULIRGs observed with NuSTAR, indicating that a significant portion of local ULIRGs are not really "X-ray faint" with respect to the flux of forbidden lines originating from the narrow line region (NLR). We propose a possible scenario that (1) the AGN in UGC 5101 is surrounded not only by Compton-thick matter located close to the equatorial plane but also by Compton-thin ($N_\mathrm{H} \sim 10^{21}$ cm$^{-2}$) matter in the torus-hole region and (2) it is accreting at a high Eddington rate with a steep UV to X-ray spectral energy distribution. Nevertheless, we argue that AGNs in many ULIRGs do not look extraordinary (i.e., extremely X-ray faint), as suggested by recent works, compared with normal Seyferts.Comment: 11 pages, 7 figures, accepted for publication in Ap