1,721,006 research outputs found
Molecular endocrinology approach in patho-physiological conditions: new markers and alternative biological matrices
Full text linkThe study of saliva for laboratory analyses is an increasing area of research with implications for basic and clinical purposes. Although this biological fluid is easy to manipulate and collect, attention must be directed to sample collection and storage, to method development and validation and to variability evaluation.
The analysis of saliva provides important information about the functioning of various organs within the body. In this respect, endocrine research certainly occupies a central role. In effect, some hormones commonly measured in plasma, such as steroids, non-steroid, peptide and protein hormones, can be detected in the oral fluid. The protein polypeptide hormones are maybe a new analytical approach of the medicine laboratory but, at present time, there are still too few investigations about protein and polypeptide hormone levels in saliva. Detection of steroid hormones is perhaps the most interesting application in salivary hormonal studies. Steroids have often been studied because salivary-free steroid hormones seem to reflect the serum-free levels. Among of these steroids, salivary cortisol measurement is today a widely accepted alternative to the determination in plasma.
In the section I of the present dissertation, a new ELISA method is explained. Research was carried out to study and validate an assay to measure salivary free IGF-I (sIGF-I) in human saliva. The detection range, the detection limit, the imprecision, the recovery and the specificity were evaluated. The pre-analytical variation was also studied. After the method validation, sIGF-I levels were measured in sedentary subjects and in athletes (protocol A and protocol C); moreover two different acute physical exercises in two groups of athletes were investigated to assess a possible effect on sIGF-I (protocol B and protocol C).
The section II describes an analysis method which used the chromatographic technique. A SPE-HPLC method with UV detection was developed and validated to simultaneously measure cortisol (sF) and cortisone (sE) in human saliva. The analytical performances, in terms of detection range, sensitivity, imprecision, recovery, were evaluated. The pre-analytical variation, with respect to collection strategy and storage conditions, was also examined. After validation, the sF and sE method was applied analyzing specimens collected from athletes, before and after a physical exercise (protocol C).
The results suggest further investigation from the laboratory point of view, taking into account the aspects related to the various forms and the specific and unspecific binding proteins (for sIGF-I assay) and to other steroid hormones and related metabolites identified and probably present in human saliva (for sF/sE assay).Lo studio della saliva nelle analisi di laboratorio è un’area di ricerca in forte crescita, per le sue implicazioni nella ricerca di base ma anche a fini clinici. Sebbene questo fluido biologico sia facile da manipolare e da raccogliere, bisogna porre attenzione ai processi di raccolta e stoccaggio del campione, nonché allo sviluppo e alla validazione di metodi analitici, assieme alla valutazione delle variabilità.
L’analisi della saliva dà importanti informazioni sul funzionamento di vari organi del corpo. In relazione a questo, la ricerca endocrina occupa certamente un ruolo centrale. Infatti, alcuni ormoni normalmente misurati nel plasma, come ormoni steroidei, ma anche ormoni non steroidei, peptidici e proteici, possono essere identificati nel fluido orale. Un nuovo approccio analitico nella medicina di laboratorio è forse rappresentato dagli ormoni polipeptidici e proteici ma, tuttora, ci sono ancora troppi pochi studi su questi ormoni salivari. La misura degli ormoni steroidi, invece, rappresenta forse l’applicazione più interessante negli studi degli ormoni salivari. Spesso gli steroidi sono studiati perché la concentrazione salivare riflette i livelli sierici. Tra i vari steroidi, la misura del cortisolo salivare è oggi una alternativa alla sua determinazione plasmatici.
Nella I sezione viene spiegato un nuovo metodo ELISA. Sono stati sviluppati test sperimentali per studiare e validare un metodo per la misura dell’IGF-I libero salivare (sIGF-I). Sono stati studiati il range di misura, la sensibilità, l’imprecisione, il recupero e la specificità. Inoltre è stata studiata anche la variabilità pre-analitica. Dopo la validazione del metodo, sono stati misurati i livelli di sIGF-I in soggetti sedentari ed in atleti (protocollo A e protocollo C); inoltre è stato studiato il possibile effetto di due differenti esercizi fisici (in acuto) sulle concentrazioni di sIGF-I (protocollo B e protocollo C).
La II sezione prende in esame un metodo di analisi che usa la tecnica cromatografia. E’ stato sviluppato e valicato un metodo SPE-HPLC con rivelazione UV per la misura contemporanea del cortisolo (sF) e del cortisone (sE) nella saliva umana. Sono state calcolate le performance analitiche (range di misura, sensibilità, imprecisione, recupero). E’ stata considerata anche la variabilità pre-analitica con particolare attenzione alle condizioni di raccolta e conservazione del campione. Dopo la validazione, questo metodo è stato applicato a campioni raccolti da un gruppo di atleti, prima e dopo un esercizio fisico (protocollo C).
I risultati ottenuti suggeriscono ulteriori approfondimenti soprattutto da un punto di vista laboratoristico, tenendo presente la possibile presenza di varie forme e di specifiche ed aspecifiche proteine di legame (per sIGF-I) e altri ormoni steroidei e loro metaboliti identificati e probabilmente presenti nella saliva umana (per sF/sE)
Verification of examination procedures in clinical laboratory for imprecision, trueness and diagnostic accuracy according to ISO 15189:2012: a pragmatic approach
Full text linkBackground The International Standard ISO 15189 is recognized as a valuable guide in ensuring high quality clinical laboratory services and promoting the harmonization of accreditation programmes in laboratory medicine. Examination procedures must be verified in order to guarantee that their performance characteristics are congruent with the intended scope of the test. The aim of the present study was to propose a practice model for implementing procedures employed for the verification of validated examination procedures already used for at least 2 years in our laboratory, in agreement with the ISO 15189 requirement at the Section 5.5.1.2. Methods In order to identify the operative procedure to be used, approved documents were identified, together with the definition of performance characteristics to be evaluated for the different methods; the examination procedures used in laboratory were analyzed and checked for performance specifications reported by manufacturers. Then, operative flow charts were identified to compare the laboratory performance characteristics with those declared by manufacturers. Results The choice of performance characteristics for verification was based on approved documents used as guidance, and the specific purpose tests undertaken, a consideration being made of: imprecision and trueness for quantitative methods; diagnostic accuracy for qualitative methods; imprecision together with diagnostic accuracy for semi-quantitative methods. Conclusions The described approach, balancing technological possibilities, risks and costs and assuring the compliance of the fundamental component of result accuracy, appears promising as an easily applicable and flexible procedure helping laboratories to comply with the ISO 15189 requirements
Salivary free insulin-like growth factor-i levels: effects of an acute physical exercise in athletes
No full textThe offer of human saliva IGF-I (sIGF-I) measurement in athletes investigation is a new proposal. The aim was to investigate the physical exercise effect on sIGF-I and explore plasma free IGF-I relation
Validation model of a laboratory-developed method for the ISO15189 accreditation: The example of salivary cortisol determination
No full textGrowth hormone isoforms,segments/fragments:Does a link exist with multifunctionality?
No full textEndocrine diagnostic tests are dependent on the molecular characteristics of protein hormones, a property that is also intimately tied to function. The structure-function relationship is of particular importance for multifunctional protein hormones such as growth hormone (GH). For clinical diagnosis, it is imperative to understand the relationship between GH structure (and its molecular fragments) and function and their potential interaction with single or multiple receptors. The existence of a single or aggregated intact GH 22 kDa form such as the 20 kDa GH isoform has been described, but GH fragments cannot be excluded a priori. Recent advances and probable similarity of GH with other protein hormones such as natriuretic peptides (ANP, BNP and their proANP and proBNP fragments) and POMC (ACTH, beta-endorphin, etc.) lend support to the hypothesis that GH fragments should also be present. This brief review focuses on GH heterogeneity and feasible post-synthesis events. The aim of the review is to describe which GH forms/fragments have already been recognized and/or are potentially present in the circulation. The impacts of GH isoforms (namely the intact 20 and 22 kDa isoforms) and fragments thereof on quantitative measurement are discussed with reference to traditional immunoassay technology and innovative immunofunctional laboratory assay
Cardiac biomarkers of acute coronary syndrome: from history to high-sensitive cardiac troponin
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