S. Masini

Cardiac natriuretic hormones, neuro-hormones, thyroid hormones and cytokines in normal subjects and patients with heart failure

Abstract 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-α (TNF-α) and interleukin-6 (IL-6). The concentrations of all CNHs and neuro-hormones 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-α, 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.

In vivo total antioxidant capacity: comparison of two different analytical methods.

Abstract 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°C until performance of assay procedures. OXY assay: The lower limit of sensitivity was 6 μmol HClO/ml. The assay was found to be linear up to 440 μmol 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 μmol/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 μmol HClO/ml. Mean OXY value in females (353.4±13.2 mmol HClO/ml) was not different from that detected in males (372±8.6 mmol 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 μmol HClO/ml, p<0.01, respectively). FRAP assay: The lower limit of sensitivity was 15 μmol/l. Linearity was observed up to 1000 μmol/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 μmol/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 μmol/l. Mean FRAP in females (469±22.5 μmol/l) was not different from that detected in males (535±25.6 mmol/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.

Analytical performance of CA 19.9, CA 125 and CA 15.3 assays as observed through an external quality assessment program

Immunoassays of the tumor markers CA 19.9, CA125 and CA 15.3 are generally acknowledged to be a useful tool in the management of cancer patients. As a consequence, many methods developed by different companies are now commercially available. However, discrepancies have been described in the results of marker determinations even when the same monoclonal antibody was used. An external quality assessment (EQA) was carried out; starting from 1989 about 110 laboratories participated; since December 1991 the program was linked with the interlaboratory program Oncocheck organized by the Service de Radiopharmacie et Radioanalyse, University of Lyon. At present more than 200 laboratories of many European countries are involved: cumulatively 47 quality control samples have been prepared and sent to the participants. This manuscript is a report on data collected for CA 19.9, CA 125, and CA 15.3.

A New Chemiluminescence Immunoassay for Triiodothyronine and Thyroxine: Evaluation Using Quality Control Sera Assayed in an Interlaboratory Survey

A recently developed chemiluminescence immunoassay system (LIA-mat) for triiodothyronine and thyroxine, set up by Byk-Sangtec Diagnostica (Dietzenbach, Germany), has been evaluated and compared with radioimmunoassays and with a chemiluminescence enhanced enzyme immunoassay (Amerlite), using control materials circulated in a national interlaboratory quality control, as well as patient sera. The LIA-mat assays are competitive methods which use coated monoclonal antibodies and triiodothyronine- or thyroxine-ABEI (aminobutylethylisoluminol) conjugate as tracers. The working range of LIA-mat T3 (computed from the within-assay precision profile) extended from 1.4 to 12.3 nmol/l; the between-assay precision was 8.1 - 19.3 CV%. Regression analysis of the LIA-mat T3 results (y) against the consensus means (x) of the participants in the national interlaboratory survey yielded: y = -0.14 + 1.05 x, r = 0.95. The working range of LIA-mat T4 extended from 33 to 515 nmol/l; the between-assay precision was 5.4 - 9.2 CV%. An excellent agreement was found between LIA-mat T4 results (y) and the consensus means (x) of the laboratories participating in the national interlaboratory survey (y = 3.79 + 1.02 x, r = 0.98).

External quality assurance of the carcinoembryonic antigen (CEA) assay: main findings in six years' experience

In 1984 we initiated a national external quality assessmnent (EQA) program (supported by the Italian National Research Council, CNR) for the CEA assay; at present, about 200 Italian laboratories are participating in the program. The laboratories assayed the quality control (QC) samples according to their routine procedures and returned the results together with the name of the method/kit they used. The collecterd results were computer-processed and reports were sent back to the participants. A significant reduction of the CVt (mean between-laboratory agreement) of the CEA assay was observed throughout the EQA survey (from 35% in 1985 to 20-25% in the last cycles). In order to better clarify the differences in variability observed in the first QC cycles against the last ones, we used the ANOVA technique to evaluate the components of variability. The improvement in between-laboratory agreement was mainly due to the reduction of the between-kit component (from 30.5% to 15.2%), rather than to the smaller decrease observed for the within-kit variability (from 18.4% to 14.0%). The results reported for QC samples from different materials showed differences in the between-lab variability and substantial changes of the kit biases, thus suggesting a different specificity of the antibodies used in the various method/kits against different families of CEA molecules. Considerable uncertainty was also encountered in the clinical classification of low pathological samples, which seems mainly due to the variability in cut-off values used by the laboratories for the clinical assessment of the same analytical results. Our data indicate a progressive increase in the reliability of CEA determination during our study and confirm that EQA has improved the reliability of analysis carried out by the participating laboratories, thus stimulating the kit manufacturers to provide more reliable products.