The derangement of neuro-endocrine control of circulation influences both disease evolution and response to treatment in patients with heart failure, but little data are available about the complex relationships between the degree of neuro-hormonal activation and clinical severity. We studied the relationships between cardiac natriuretic hormones (CNHs) and several neuro-hormones and immunological markers in a prospective cohort of 105 consecutive patients with cardiomyopathy (77 men and 28 women, mean age 66.7+/-12.4 years, range 33-89 years). We assayed the circulating levels of CNHs (atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)), plasma renin activity (PRA), aldosterone, cortisol, adrenaline, noradrenaline, thyroid hormones and thyroid stimulating hormone (TSH), tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). The concentrations of all CNHs and neurohormones were higher in patients with heart failure compared to normal subjects, except for free triiodothyronine (FT3), which was below normal values. ANP was positively related to NYHA class, IL-6, adrenaline, noradrenaline and cortisol, while negatively with ejection fraction and FT3. BNP was positively related to age, NYHA class, IL-6, TNF-alpha, adrenaline, noradrenaline and cortisol, while negatively with ejection fraction and FT3. A stepwise multiple linear regression indicated that plasma ANP depended only on ejection fraction, adrenaline and noradrenaline values, while for plasma BNP variation NYHA class contributed too. Our data confirm a progressive activation of hormonal and immunological systems in patients with heart failure. Furthermore, CNH circulating levels in heart failure are affected not only by cardiac function and disease severity, but also by activation of neuro-hormonal and stress-related cytokine systems, as well as by the thyroid hormones, even on usual medical treatment.

Several methods to assess the total antioxidant capacity (TAC) are available. However, the final value of measured TAC in the sample depends on the procedure used in every specific assay. This makes crucial the comparison of different analytical methods. The aim of our study was to evaluate analytical characteristics and laboratory reliability of two different assays: the ferric-reducing ability (FRAP) assay and a new spectrophotometric test (OXY-adsorbent test, Diacron, Italy). Unselected outpatients referred to the Institute of Clinical Physiology were studied (n = 187, 58 females, 129 males, mean age: 65 +/- 13 years). All blood samples were maintained on ice, centrifuged within 15 minutes after blood collection and then stored at -80 degrees C until performance of assay procedures. OXY assay: The lower limit of sensitivity was 6 micromol HClO/ml. The assay was found to be linear up to 440 micromol HClO/ml (r = -0.99, p < 0.001). Absorbance was linear over a wide concentration range with solutions containing uric acid in purified form (0-1000 micromol/l, r = -0.996, p < 0.001), serum (r = -0.99, p < 0.01) or plasma serially diluted (r = -0.99, p < 0.01). Mean value in plasma samples accounted for 366.2 +/- 7.2 micromol HClO/ml. Mean OXY value in females (353.4 +/- 13.2 micromol HClO/ml) was not different from that detected in males (372 +/- 8.6 micromol HClO/ml). A significant difference was observed between subjects without and with hypertension in serum OXY levels (344.8 +/- 9.9 and 383.2 +/- 10 micromol HClO/ml, p < 0.01, respectively). FRAP assay: The lower limit of sensitivity was 15 micromol/l. Linearity was observed up to 1000 micromol/l (r = 0.998, p < 0.001). Absorbance was linear over a wide concentration range with solutions containing uric acid in purified form (0-1000 micromol/l, r = 0.997, p < 0.001), serum (r = 0.99, p < 0.01) or plasma serially diluted (r = 0.99, p < 0.01). FRAP mean value in plasma samples, evaluated in 102 patients, accounted for 514.1 +/- 19.1 micromol/l. Mean FRAP in females (469 +/- 22.5 micromol/l) was not different from that detected in males (535 +/- 25.6 micromol/l). FRAP vs. OXY: A significant direct relationship was observed when comparing FRAP with OXY levels in the whole population (r = 0.22, p < 0.05). Neither of the methods are expensive and they are speedy and simple to perform. Values are reproducible and linearly correlated to the concentration of antioxidants present in the samples. For this reason, these methods may be considered practicable indicators of total antioxidant capacity, for routinely potential use in every laboratory and useful in all the studies concerning the evaluation of oxidative stress.

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Concentrations of interleukin 2 receptor (sIL-2R) have been suggested as a marker of rejection episodes after organ transplantation. To evaluate the analytical performance of a "sandwich-type" enzyme immunoassay method for sIL-2R and to verify whether increased concentrations of sIL-2R might be a useful marker of allograft rejection, we quantified sIL-2R in serum samples from heart- or kidney-transplant patients. The mean (+/- SD) pre-transplant value of sIL-2R (592 +/- 209 kilo-units/L) in heart-transplant patients was significantly higher (P less than 0.01) than that observed in controls (350 +/- 101 kilo-units/L). After heart transplantation, the concentrations of sIL-2R slowly decreased to baseline in successfully treated patients but increased significantly (1129 +/- 215 kilo-units/L; P less than 0.01) during acute rejection crisis. However, severe infections were also associated with a significant increase of sIL-2R, so the sIL-2R test is not specific for allograft rejection. The mean pre-transplant concentration of sIL-2R was also increased (1943 +/- 878 kilo-units/L) in 26 renal-transplant patients; after transplantation, this value returned to normal, as did that for creatinine, but persisted steadily high in five patients who experienced acute tubular necrosis. In this group of patients, the sIL-2R concentration increased by 1.5- to fourfold, both during acute rejection episodes and in clinically evident infection; thus measurement of creatinine and sIL-2R concentrations can help to distinguish between rejection, infection, and cyclosporine toxicity. In two episodes of mild cyclosporine-induced nephrotoxicity, we observed slight increases in serum creatinine (which returned to baseline when the cyclosporine dose was decreased) not associated with an increase in sIL-2R. We conclude that systematic monitoring of sIL-2R together with other biochemical and clinical markers may be useful in the management of kidney-transplant patients.