Classical Skin Lesions Resembling Infective Endocarditis in a Patient with an Infected Aortic Composite Graft

Non-alcoholic fatty liver infiltration in children: an underdiagnosed evolving disease

Non-alcoholic fatty liver disease (NAFLD) constitutes the most common liver disease, one that is still underdiagnosed in pediatric populations (as well as in the general population), this due to the progressive increase in childhood obesity observed both in developed and developing countries during the last few decades. The pathophysiology of the disease has not been thoroughly clarified yet. The condition displays common pathways in adults and children; however, there are age-related differences. Unlike adults, children with NAFLD require extensive laboratory analysis, because underlying pathologies other than obesity may contribute to the evolution of the disease. Despite the presence of several serum markers and imaging techniques that contribute to NAFLD diagnosis, liver biopsy remains the gold standard diagnostic procedure. Early intervention and obesity prevention are mandatory, as NAFLD is reversible at an early stage. If left undiagnosed and untreated, NAFLD can progress to steatohepatitis (NASH) and subsequent liver failure, a potentially lethal complication. Of note, there are no treatment options when advanced liver fibrosis occurs. This review summarizes literature data on NAFLD in childhood indicating that this is an evolving disease and a significant component of the metabolic syndrome. Pediatricians should be aware of this entity, screening children at high risk and providing appropriate early management, in collaboration with pediatric subspecialists.

Challenges and perspectives in obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is a major challenge for physicians and healthcare systems throughout the world. The high prevalence and the impact on daily life of OSA oblige clinicians to offer effective and acceptable treatment options. However, recent evidence has raised questions about the benefits of positive airway pressure therapy in ameliorating comorbidities.

An international expert group considered the current state of knowledge based on the most relevant publications in the previous 5 years, discussed the current challenges in the field, and proposed topics for future research on epidemiology, phenotyping, underlying mechanisms, prognostic implications and optimal treatment of patients with OSA.

The group concluded that a revision to the diagnostic criteria for OSA is required to include factors that reflect different clinical and pathophysiological phenotypes and relevant comorbidities (e.g.nondipping nocturnal blood pressure). Furthermore, current severity thresholds require revision to reflect factors such as the disparity in the apnoea–hypopnoea index (AHI) between polysomnography and sleep studies that do not include sleep stage measurements, in addition to the poor correlation between AHI and daytime symptoms such as sleepiness. Management decisions should be linked to the underlying phenotype and consider outcomes beyond AHI.

Association between continuous positive airway pressure and serum aminotransferases in patients with obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) has been suggested to be a potential contributing factor for nonalcoholic fatty liver disease (NAFLD). Studies on the association between continuous positive airway pressure (CPAP) and NAFLD in OSA patients are limited and controversial.

OBJECTIVES

The aim of this study was to assess the relationship between OSA and NAFLD and the effect of CPAP therapy on serum aminotransferase levels in OSA patients.

METHODS

A total of 160 consecutive patients who underwent standard polysomnography were enrolled. Blood samples were obtained in the morning after sleep for biological profile measurements. Non-invasive ultrasound techniques were used to assess liver steatosis and fibrosis. Within the OSA group, serum aminotransferases were detected before and after CPAP treatment.

RESULTS

Alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase, and liver steatosis score increased significantly with an increase in OSA severity. Stepwise multiple regression with liver steatosis score, ALT, AST as dependent variable, respectively, apnea-hypopnea index (β = 0.447, p = 0.020; β = 0.266, p = 0.001; β = 0.351, p = 0.020, respectively) significantly predicted the liver steatosis score, ALT, AST after adjustment for confounders. After 3 months of CPAP treatment, there was a significant decrease in both ALT (54.20 ± 24.34 vs. 46.52 ± 24.95, p = 0.000) and AST (31.82 ± 8.91 vs. 29.00 ± 8.34, p = 0.039).

CONCLUSIONS

OSA severity was independently associated with liver steatosis and elevation of serum aminotransferases. 3 months of CPAP therapy were associated with a statistically significant improvement on liver injury in OSA patients.

Intermittent hypoxia upregulates hepatic heme oxygenase-1 and ferritin-1, thereby limiting hepatic pathogenesis in rats fed a high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is prevalent in patients with sleep apnea syndrome (SAS). Intermittent hypoxia (IH) and a high-fat diet (HFD) reproduce SAS and NAFLD, respectively, in rodents. In this study, rats were fed either an HFD or a standard diet (SD) for 2 weeks, and breathed either IH air or normoxic air for 4 days (early phase) or 6 weeks (late phase), with the same diets maintained during the exposure. HFD increased hepatic lipid accumulation, as detected by oil-red staining and triglyceride content. However, IH exposure reversed the hepatic steatosis at the late phase in these HFD-rats. IH exposure also increased hepatic expression of HO-1 and iron-binding protein ferritin-1 at the late phase, in association with increase in serum iron, bilirubin, and hepatic levels of lipid peroxides, such as 4-hydroxy-2-nonenal (HNE). IH exposure increased serum levels of hemoglobin (Hb) at the early phase and immunofluorescence of Hb and HO-1 in CD68-positive Kupffer cells (KCs) at the late phase. These findings support that IH induces erythrocytosis, erythro-phagocytosis, and generation of Hb in the KCs. The Hb promotes HO-1 expression in KCs, thereby produces iron, bilirubin, and carbon monoxide (CO). The iron would be either sequestrated by ferritin-1, transferred to the bone marrow for erythropoiesis, or would produce hydroxyradicals and HNE in the liver of rats fed an HFD. HNE might also contribute to the upregulation of HO-1, transferrin-1, and IκB, thereby limiting hepatic steatosis and inflammation via inhibition of nuclear factor κB (NFκB) activation.

Translational approaches to understanding metabolic dysfunction and cardiovascular consequences of obstructive sleep apnea

Obstructive sleep apnea (OSA) is known to be independently associated with several cardiovascular diseases including hypertension, myocardial infarction, and stroke. To determine how OSA can increase cardiovascular risk, animal models have been developed to explore the underlying mechanisms and the cellular and end-organ targets of the predominant pathophysiological disturbance in OSA-intermittent hypoxia. Despite several limitations in translating data from animal models to the clinical arena, significant progress has been made in our understanding of how OSA confers increased cardiovascular risk. It is clear now that the hypoxic stress associated with OSA can elicit a broad spectrum of pathological systemic events including sympathetic activation, systemic inflammation, impaired glucose and lipid metabolism, and endothelial dysfunction, among others. This review provides an update of the basic, clinical, and translational advances in our understanding of the metabolic dysfunction and cardiovascular consequences of OSA and highlights the most recent findings and perspectives in the field.

Nonalcoholic fatty liver disease

On the basis of strong research and consensus, nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in children and is soon to be the most common indication for liver transplantation in adults. Although the disease begins as simple steatosis, some patients may progress to nonalcoholic steatohepatitis (NASH) and cirrhosis, making early identification and treatment critical.• The diagnosis of NAFLD can be challenging because patients are typically asymptomatic, with no major clinical symptoms of liver disease. Overweight and obese children are at the highest risk for disease. (1)(2)• On the basis of moderate research and consensus, serum ALT is usually mildly elevated but is an imperfect test with a low sensitivity for detecting NAFLD at commonly used thresholds.(10) Liver biopsy is still considered the gold standard for diagnosis but is too invasive for population-level screening and is often used selectively. Novel, noninvasive diagnostic modalities and serum biomarkers are currently being studied but warrant further validation, especially in children.• On the basis of moderate research and consensus, assessing serum liver tests in any overweight or obese child is reasonable.Liver disease should be suspected if the serum ALT is ‡22 U/L(0.37 mkat/L) in girls and ‡25 U/L (0.42 mkat/L) in boys. (10)Subspecialist referral should be considered for those with a normal BMI, persistent ALT elevation longer than 6 months,specific symptoms of advanced liver disease such as splenomegaly, or concerning laboratory findings on selected screening tests.• On the basis of strong research evidence, weight loss is the most efficacious treatment for NAFLD.• On the basis of some research and consensus, initiation of vitamin E therapy (400 IU BID) may be started, although its use probably should be restricted to those children with biopsy-proven disease. (12)• On the basis of some research and consensus, novel elastography-based imaging modalities are being studied in children and several drugs show promise in treating NAFLD.

Reduction of oxidative stress attenuates lipoapoptosis exacerbated by hypoxia in human hepatocytes

Chronic intermittent hypoxia, a characteristic of obstructive sleep apnea (OSA), is associated with the progression of simple hepatic steatosis to necroinflammatory hepatitis. We determined whether inhibition of a hypoxia-induced signaling pathway could attenuate hypoxia-exacerbated lipoapoptosis in human hepatocytes. The human hepatocellular carcinoma cell line (HepG2) was used in this study. Palmitic acid (PA)-treated groups were used for two environmental conditions: Hypoxia (1% O2) and normoxia (20% O2). Following the treatment, the cell viability was determined by the 3,4-(5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt (MTS) assay, and the mechanism of lipoapoptosis was evaluated by Western blotting. Hypoxia exacerbated the suppression of hepatocyte growth induced by palmitic acid via activation of mitochondrial apoptotic pathways as a result of endoplasmic reticulum (ER) and oxidative stresses. Ammonium pyrrolidine dithiocarbamate, a scavenger of reactive oxygen species, attenuated the hypoxia-exacerbated lipoapoptosis in hepatocytes, whereas glycerol, which reduces ER stress, did not. This may have been because inhibition of oxidative stress decreases the expression of pro-apoptotic proteins, such as caspase 9 and cytochrome c. These results suggested that modulation of apoptotic signaling pathways activated by oxidative stress can aid in identifying novel therapeutic strategies for the treatment of nonalcoholic steatohepatitis (NASH) with OSA. Further in vivo studies are necessary to understand the pathophysiologic mechanism of NASH with OSA and to prove the therapeutic effect of the modulation of the signaling pathways.