Carmen Mugueta

Advantage of salivary cortisol measurements in the diagnosis of glucocorticoid related disorders

OBJECTIVE Salivary cortisol in the assessment of glucocorticoid related disorders. DESIGN-METHODS: Serum and salivary cortisol were measured in 189 patients (22 Cushings syndrome, 67 pseudo-Cushing, 11 Addisons disease, 89 controls) at 8:00 and 24:00 h. RESULTS Serum and salivary cortisol correlated in the whole study population (r=0.62, p=0.000). Morning serum and saliva cortisol in Addisons disease were lower than in controls (6.74+/-1.69 vs 22.58+/-1.78 microg/dL, and 0.15+/-0.25 vs 0.67+/-0.12 microg/dL) (p<0.001). Morning serum cortisol was similar in controls and patients with Cushings syndrome or pseudo-Cushing (22.58+/-1.78 vs 13.96+/-6.02 vs 16.13+/-1.69 microg/dL). Morning serum and salivary cortisol at 8:00 had the same sensitivity to distinguish patients with Addisons disease from healthy controls. 24:00 am serum cortisol in controls (2.61+/-0.20 microg/dL) was lower than in the pseudo-Cushing group (6.53+/-0.77 microg/dL, p<0.001) and in Cushings syndrome (10.90+/-2.36 microg/dL, p=0.003). 24:00 am salivary cortisol in controls (0.0025+/-0.001 microg/dL) was lower than in patients with Cushings syndrome (0.58+/-0.11 microg/dL, p<0.001) and those higher than in patient with pseudo-Cushing (0.10+/-0.06 microg/dL, p=0.001). Both salivary cortisol and serum cortisol presented high specificity (82% and 100%) to detect Cushings syndrome but salivary cortisol higher sensitivity (saliva 88% and serum 50%). CONCLUSION Morning salivary cortisol is as good as serum as screening test for patients with Addisons disease and nighttime salivary cortisol is more adequate than serum in the screening of Cushings syndrome.

Impaired adiponectin-AMPK signalling in insulin-sensitive tissues of hypertensive rats

AIMS Adiponectin improves insulin sensitivity by decreasing lipid accumulation in insulin-sensitive tissues. The aim of this study was to investigate whether these effects are altered in hypertension. MAIN METHODS Adiponectin receptors (AdipoR1 and AdipoR2) and adiponectin-related enzymes were measured by real-time PCR and Western-blot in insulin-sensitive tissues of 10-week-old male spontaneously hypertensive rats (SHR). Intrahepatic and intramyocellular triglycerides were determined by enzymatic methods. KEY FINDINGS SHR showed overweight, dyslipidemia, glucose intolerance and insulin resistance. Circulating concentrations of adiponectin as well as the mRNA and protein expression of adiponectin in epididymal and subcutaneous fat depots were significantly increased in hypertensive rats. Adiponectin mRNA levels were strongly associated with PPARgamma mRNA levels in both epididymal (r=0.54, P<0.05) and subcutaneous (r=0.93, P<0.0001) fat. The expression of AdipoR1 and AdipoR2, acetyl-CoA carboxylase (ACC), as well as carnitine palmitoyl transferase 1 (CPT1), were increased in skeletal muscle of SHR. These changes were not observed in the liver of SHR. In addition, in spite of the hyperadiponectinemia, SHR showed similar activation of AMP-activated protein kinase (AMPK) and a lower phosphorylation degree of its downstream ACC in liver and skeletal muscle. Accordingly, SHR exhibited a significant increase in intrahepatic (approximately 40%) and intramyocellular (approximately 60%) lipid accumulation. SIGNIFICANCE These findings suggest that dysregulation of the adiponectin downstream effectors contributes to increased intrahepatic and intramyocellular triglycerides in SHR. Hyperadiponectinemia together with overexpression of adiponectin receptors in skeletal muscle may reflect a defective compensatory mechanism to overcome adiponectin resistance in hypertensive rats.

Laboratory approach to mitochondrial diseases

Dysfunction in mitochondrial processes has been related to several pathologies. In these disorders, the cell suffers oxidative imbalance that is mostly due to defects in pyruvate metabolism, mitochondrial fatty acids oxidation, the citric acid cycle or electron transport by the mitochondrial respiratory chain. These metabolic alterations produce mitochondrial diseases that have been related to inherited syndromes, such as MERRF or MELAS. The main affected organs are brain, skeletal muscle, kidney, heart and liver, because of the high energetic demand and the oxidative metabolism. Moreover, the relationship between mitochondrial dysfunction and neurodegenerative processes, such as Parkinson disease or Alzheimer disease, as well as ageing, has been shown. Because mitochondrias are the target of several xenobiotics, such as aspirin, AZT or alcohol consumption, motochondrial impairment has also been proposed as a mechanism of toxicity. Most laboratory tests that are available in the diagnosis of mitochondrial illness are assayed in tissue biopsies and are usually difficult to interpret. Recently, it has been shown that non-invasive techniques, such as nuclear magnetic resonance or the 2-keto [1-13C] isocaproic acid breath test, may be useful to assess mitochondrial function. This article attempts to show the laboratory approach to mitochondrial diseases, reviewing new techniques that could be of great value in the research of mitochondrial function, such as the 2-keto[1-13C]isocaproic breath test.ResumenLa alteración de la función mitocondrial se ha relacionado con una amplia gama de patologías de origen diverso. Básicamente, los defectos en el metabolismo del piruvato y en la oxidación mitocondrial de los ácidos grasos, junto con deficiencias en el ciclo del ácido cítrico y en el funcionamiento de la cadena respiratoria, generan un estado de estrés oxidativo en las células que sufren este tipo de desórdenes. Estas alteraciones mitocondriales no sólo están presentes en síndromes congénitos como MERRF o MELAS sino que también se han relacionado con procesos neurodegenerativos, como la enfermedad de Alzheimer o la enfermedad de Parkinson, con el proceso de envejecimiento y con el mecanismo de toxicidad de diversos xenobióticos, come el alcohol o la aspirina.La mayor parte de las pruebas disponibles en el laboratorio para estudiar la función mitocondrial, presentan una interpretación difícil además de requerir una toma de muestra cruenta, ya que el estudio suele realizarse en biopsias. Recientemente, se han propuesto técnicas no invasivas, como la resonancia magnética nuclear y las pruebas de aliento con isótopos estables, como pruebas útiles en el estudio de la función mitocondrial.El objetivo de este trabajo es la revisión de las pruebas disponibles en el laboratorio para el estudio de las citopatías mitocondriales y de las técnicas empleadas, mostrando nuevas pruebas que pueden resultar útiles en el estudio de la función mitocondrial, como el test del aliento del ácido 2-ceto[1-13C]isocaproico.

Factors related to increased resting energy expenditure in men with liver cirrhosis.

Objective Hypermetabolism in cirrhosis is associated with a high risk of complications and mortality. However, studies about underlying mechanisms are usually focussed on isolated potential determinants and specific etiologies, with contradictory results. We aimed at investigating differences in nutrition, metabolic hormones, and hepatic function between hypermetabolic and nonhypermetabolic men with cirrhosis of the liver. Patients and methods We prospectively enrolled 48 male cirrhotic inpatients. We evaluated their resting energy expenditure (REE) and substrate utilization by indirect calorimetry, body composition by dual-energy X-ray absorptiometry, liver function, and levels of major hormones involved in energy metabolism by serum sample tests. Patients with ascites, specific metabolic disturbances, and hepatocellular carcinoma were excluded. Results REE and REE adjusted per fat-free mass (FFM) were significantly increased in cirrhotic patients. Overall, 58.3% of cirrhotic patients were classified as hypermetabolic. Groups did not differ significantly in age, etiology of cirrhosis, liver function, presence of ascites, use of diuretics, &bgr;-blockers, or presence of transjugular intrahepatic portosystemic shunts. Hypermetabolic cirrhotic patients had lower weight, BMI (P<0.05), nonprotein respiratory quotient (P<0.01), leptin (P<0.05), and leptin adjusted per fat mass (FM) (P<0.05), but higher FFM% (P<0.05) and insulin resistance [homeostatic model assessment-insulin resistance (HOMA-IR)] (P<0.05). Only HOMA-IR, leptin/FM, and FFM% were independently related to the presence of hypermetabolism. Conclusion Hypermetabolic cirrhotic men are characterized by lower weight, higher FFM%, insulin resistance, and lower leptin/FM when compared with nonhypermetabolic men. HOMA-IR, FFM%, and leptin/FM were independently associated with hypermetabolism, and may serve as easily detectable markers of this condition in daily clinical practice.

Ghrelin reduces TNF-α-induced human hepatocyte apoptosis, autophagy and pyroptosis: role in obesity-associated NAFLD.

Context Human obesity is associated with increased circulating TNF-α, a proinflammatory cytokine that induces hepatocyte cell death. Objective The potential beneficial effects of acylated and desacyl ghrelin in the progression of nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis in obesity via the inhibition of TNF-α-induced hepatocyte apoptosis, autophagic cell death, and pyroptosis were investigated. Design, Settings, and Participants Plasma ghrelin isoforms and TNF-α were measured in 158 participants, and hepatocyte cell death was evaluated in liver biopsies from 76 patients with morbid obesity undergoing bariatric surgery with available liver echography and pathology analysis. The effect of acylated and desacyl ghrelin on basal and TNF-α-induced cell death was determined in vitro in human HepG2 hepatocytes. Results Circulating TNF-α and the acylated/desacyl ghrelin ratio were increased, whereas desacyl ghrelin levels were decreased in patients with obesity and NAFLD. Six months after bariatric surgery, decreased acylated/desacyl ghrelin levels, and improved hepatic function were found. Patients with obesity and type 2 diabetes showed increased hepatic ghrelin O-acyltransferase transcripts as well as an increased hepatic apoptosis, pyroptosis, and compromised autophagy. In HepG2 hepatocytes, acylated and desacyl ghrelin treatment reduced TNF-α-induced apoptosis, evidenced by lower caspase-8 and caspase-3 cleavage, as well as TUNEL-positive cells and pyroptosis, revealed by decreased caspase-1 activation and lower high-mobility group box 1 expression. Moreover, acylated ghrelin suppressed TNF-α-activated hepatocyte autophagy, as evidenced by a decreased LC3B-II/I ratio and increased p62 accumulation via AMPK/mTOR. Conclusions Ghrelin constitutes a protective factor against hepatocyte cell death. The increased acylated/desacyl ghrelin ratio in patients with obesity and NAFLD might constitute a compensatory mechanism to overcome TNF-α-induced hepatocyte apoptosis, autophagy, and pyroptosis.