Determination of renin plasma levels is useful in the diagnosis of hypertension and in the therapeutic follow-up of hypertensive patients. Plasmatic concentration of renin decreases in patients with ...hypertension due to a primary hyperaldosteronism, contrary to renovascular hypertension where concentrations of renin and aldosterone are both elevated. Blood samples (serum, EDTA plasma) were analysed using two different chemiluminiscent methods CLIA LIAISON® and radioimmunoassay for aldosterone (IMMUNOTECH Beckman Coulter) and renin (Cisbio Bioassay) measurements were compared. We used both methods to ascertain the correlation between serum vs. EDTA plasma levels of aldosterone (RIA, CLIA) and renin (IRMA, CLIA) and to compare aldosterone to renin ratios for CLIA and for radioimmunoassay: serum aldosterone to plasma renin and plasma aldosterone to plasma renin. We compared serum aldosterone CLIA vs. RIA (r
P
=0.933, P<0.001) and plasma renin determined using CLIA vs. IRMA (r
P
=0.965, P=0.062). Furthermore, we used both methods to establish the correlation between the serum vs. plasma levels of aldosterone: RIA (r
P
=0.980, P<0.001); CLIA (r
P
=0.994, P=0.353) and serum vs. plasma levels of renin: IRMA (r
P
=0.948, P<0.001); CLIA (r
P
=0.921, P=0.011). Aldosterone (serum, plasma) to plasmatic renin ratios for CLIA (r
P
=0.999, P=0.286) and for radioimmunoassay (r
P
=0.992, P=0.025). Our data demonstrate that renin and aldosterone concentrations obtained using CLIA correlate with renin and aldosterone concentrations using radioimmunoassay methods. Correlation coefficients of pair results ranged from 0.921 to 0.994. Aldosterone (serum, EDTA plasma) to plasmatic renin ratios are comparable and any of them can be used with no significant differences found.
Circulating thyroglobulin measurements is a highly specific test in the management of patients affected by differentiated thyroid cancer after total thyroidectomy, followed by radioiodine ablation. ...The aim of our study was to compare two thyroglobulinimmunoradiometric assays (INEP, Serbia and Cisbio Bioassays, France). Study included 42 patients of both genders with DTC. The subjects were on suppres¬sive doses of levothyroxine and followed up. Results showed concordance between the two assay methods for determining serum thyroglobulin for 39 (92.85%) patients. Statistical analysis showed that there was a direct correlation between two IRMA tests, with a positive correlation coefficient r=0.613 (p 0.05). We concluded that there is good agreement between the two thyroglobulin assays compared in this study.
Myostatin is a muscle derived factor that functions as a negative regulator of skeletal muscle growth. Induction of myostatin expression was observed in rodent models of muscle wasting and in ...cachectic patients with cancer or pulmonary disease. Therefore, there is an increasing interest to use serum myostatin as a biomarker.
We established an immunoradiometric sandwich assay (IRMA), which uses a commercially available chicken polyclonal, affinity purified antibody directed against human myostatin prodomain. We determined the serum concentrations of myostatin prodomain in 249 healthy individuals as well as 169 patients with heart failure, 53 patients with cancer and 44 patients with chronic pulmonary disease.
The IRMA had a detection limit of 0.7ng/ml, an intraassay imprecision of ≤14.1% and an interassay imprecision of ≤ 18.9%. The specificity of our assay was demonstrated by size exclusion chromatography, detection of myostatin by Western-blotting and a SMAD-dependent transcriptional-reporter assay in the signal-rich serum fractions, as well as lack of interference by unspecific substances like albumin, hemoglobin or lipids. Myostatin prodomain was stable at room temperature and resistant to freeze-thaw cycles. Apparently healthy individuals over the age of 55 had a median myostatin prodomain serum concentration of 3.9ng/ml (25(th)-75(th) percentiles, 2-7ng/ml) and we could not detect increased levels in patients with stable chronic heart failure or cancer related weight loss. In contrast, we found strongly elevated concentrations of myostatin prodomain (median 26.9ng/ml, 25(th)-75(th) percentiles, 7-100ng/ml) in the serum of underweight patients with chronic pulmonary disease.
We established a highly specific IRMA for the quantification of myostatin prodomain concentration in human serum. Our assay could be useful to study myostatin as a biomarker for example in patients with chronic pulmonary disease, as we detected highly elevated myostatin prodomain serum levels in underweight individuals of this group.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Immunoassays employed to measure C-peptide in rat serum neither have high sensitivity nor good range. Hence, the aim of this work was to develop a sensitive and specific user friendly ...immunoradiometric assay (IRMA) utilizing in-house magnetizable cellulose particles for quantification of C-peptide in rat serum. For development of IRMA, detector antibody (M
1
*) was prepared by chloramine-T method using
125
I and capture antibody (SM
2
) was prepared by carbonyldiimidazole (CDI) activation method. The matched pair M
1
*-SM
2
yielded an assay with adequate sensitivity (0.24 ng/ml) and range (0–20 ng/ml). C-peptide concentrations in rat serum samples (
n
= 30) analyzed using the developed assay ranged between 0.3 and 0.54 ng/ml. The reported C-peptide range can be used as a reference in impending diabetic research carried out using rat models.
To discuss new insights regarding how sensitive (second-generation) thyroglobulin immunometric assays (TgIMAs), (functional sensitivities ≤0.10 μg/L) necessitate different approaches for ...postoperative thyroglobulin monitoring of patients with differentiated thyroid cancer (DTC), depending on the presence of thyroglobulin autoantibodies (TgAbs).
Reliable low-range serum thyroglobulin measurement has both enhanced clinical utility and economic advantages, provided TgAb is absent (∼75% DTC patients). Basal nonthyroid-stimulating hormone (TSH) stimulated TgIMA measurement obviates the need for recombinant human TSH stimulation because basal TgIMA below 0.20 μg/L has comparable negative predictive value (>95%) to recombinant human TSH-stimulated thyroglobulin values below the cutoff of 2 μg/L. Now that radioiodine remnant ablation is no longer considered necessary to treat low-risk DTC, the trend and doubling time of low basal thyroglobulin values arising from postsurgical thyroid remnants have recognized prognostic significance. The major limitation of TgIMA testing is interference by TgAb (∼25% DTC patients), causing TgIMA underestimation that can mask disease. When TgAb is present, the trend in TgAb concentrations (measured by the same method) can serve as the primary (surrogate) tumor-marker and be augmented by thyroglobulin measured by a TgAb-resistant class of method (radioimmunoassay or liquid chromatography-tandem mass spectrometry).
The growing use of TgIMA measurement is changing paradigms for postoperative DTC monitoring. When TgAb is absent, it is optimal to monitor the basal TgIMA trend and doubling time (using the same method) in preference to recombinant human TSH-stimulated thyroglobulin testing. When TgAb is present, interference renders TgIMA testing unreliable and the trend in serum TgAb concentrations per se (same method) can serve as a (surrogate) tumor-marker.
Although there is growing evidence of links between the cortisol stress response and personality, the nature of the relationships and the underlying mechanisms require further clarification. The ...purpose of this study was to examine associations between personality traits and cortisol responses to stress using the Revised NEO Personality Inventory five-factor model of personality. In total, 68 healthy adults, aged 18-30 years, completed the personality assessment and underwent a laboratory psychological stress test that consisted of a 5 min speech and 5-min of mental arithmetic. Findings showed that in the sample as a whole, less Openness was associated with lower cortisol responses to the challenge. Cortisol responses also corresponded to certain personality dimensions in a gender-specific manner. Blunted cortisol responses were associated with higher Neuroticism in women and with lower Extraversion in men. These findings suggest that personality traits that have been traditionally associated with greater psychopathology were also associated with blunted HPA axis responses to stress.
Growth-differentiation factor 15 (GDF15) is a member of the transforming growth factor beta (TGF-beta) cytokine superfamily. There has been increasing interest in using circulating GDF15 as a ...biomarker in patients, for example those with cardiovascular disease.
We developed an IRMA that uses a polyclonal, affinity chromatography-purified goat antihuman GDF15 IgG antibody, assessed the preanalytic characteristics of GDF15, and determined circulating GDF15 concentrations in 429 apparently healthy elderly individuals and 153 patients with chronic heart failure (CHF).
The assay had a detection limit of 20 ng/L, an intraassay imprecision of < or =10.6%, and an interassay imprecision of < or =12.2%. Specificity was demonstrated with size-exclusion chromatography, parallel measurements with polyclonal and monoclonal anti-GDF15 antibody, and lack of cross-reactivity with TGF-beta. The assay was not appreciably influenced by the anticoagulant matrix or unrelated biological substances. GDF15 was stable at room temperature for 48 h and resistant to 4 freeze-thaw cycles. Apparently healthy, elderly individuals presented with a median GDF15 concentration of 762 ng/L (25th-75th percentiles, 600-959 ng/L). GDF15 concentrations were associated with age and with cystatin C and C-reactive protein concentrations. CHF patients had increased GDF15 concentrations that were closely related to disease severity.
The IRMA can detect GDF15 in human serum and plasma with excellent sensitivity and specificity. The reference limits and confounding variables defined for apparently healthy elderly individuals and the favorable preanalytic characteristics of GDF15 are expected to facilitate future studies of GDF15 as a biomarker in various disease settings, including CHF.
For the last decade chromogranin-A (CgA) has been a well-established marker for neuroendocrine tumor (NET), and N-terminal pro-brain natriuretic peptide (NT-proBNP) has been a useful marker for left ...ventricular dysfunction. This study examined the diagnostic value of CgA and NT-proBNP for carcinoid heart disease (CHD), and their prognostic value for overall survival in NET patients.
Serum samples were obtained and cardiac ultrasound studies performed in 102 NET patients. The criterion for mild and severe CHD was tricuspid regurgitation stage I/II and III/IV, respectively. Proportional odds and Cox proportional hazards models were constructed respectively to identify the association between CHD and overall survival with patient characteristics and the two markers.
Severe CHD was found in 15 (15%) of 102 patients, 13 of whom had elevated NT-proBNP levels. In the univariate proportional odds model CHD was correlated with age (P = .007), CgA (P = .002), and NT-proBNP (P < .001), whereas in the multivariate model NT-proBNP and CgA were significantly associated with CHD (P < .001 and P = .01). In the univariate Cox models, age (P = .04), sex (P = .03), CgA (P = .003), and NT-proBNP (P = .04) were related to overall survival, and in the multivariate model CgA and NT-proBNP remained significantly related to overall survival (P = .002 and P = .04, respectively).
NT-proBNP and CgA are very important markers in the diagnosis of CHD in patients with NET. Furthermore, patients with elevated NT-proBNP in addition to elevated CgA levels showed worse overall survival than patients with elevated CgA alone.
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