Jhessica Alessandroni

Pre-analytical operating procedures for serum Low Molecular Weight protein profiling

Biological specimen collection and storage are an integral component of serum proteomics research. Although many efforts have been posed to address the effects of pre-analytical procedures, standardized protocols for collection and storage of samples for Low Molecular Weight (LMW) proteome profiling are still needed. Here we report a systematic analysis on the influence of pre-analytical factors [clotting times, temperature and time storage, addition of protease inhibitor (PI)] on serum LMW proteome profiling. Moreover, a comparison between manual versus automated peptide purification by functionalized magnetic bead-based MALDI-MS approach was performed. The results demonstrated best serum LMW proteins recovery and stability using a clotting time between 1 and 2h, with serum stored up to 2h either at room temperature or at 4 degrees C, independently of PI addition. PI addition to whole blood resulted in a lower number of LMW peaks detected. Finally, minimal effects on serum proteome profiles were observed after 1-month storage at -80 degrees C, independently of PI addition on whole blood and/or serum. In conclusion, the use of standardized pre-analytical and storage procedures together with an automated peptide purification might minimize potential bias on serum LMW profiling results, thus allowing a better homogeneity and reproducibility in future proteomics studies.

RFID as a new ICT tool to monitor specimen life cycle and quality control in a biobank

Background Biospecimen quality is crucial for clinical and translational research and its loss is one of the main obstacles to experimental activities. Beside the quality of samples, preanalytical variations render the results derived from specimens of different biobanks or even within the same biobank incomparable. Specimens collected along the years should be managed with a heterogeneous life cycle. Hence, we propose to collect detailed data concerning the whole life cycle of stored samples employing radio-frequency identification (RFID) technology. Methods We describe the processing chain of blood biosamples that is operative at the biobank of IRCSS San Raffaele, Rome, Italy (BioBIM). We focus on the problem of tracing the stages following automated preanalytical processing: we collected the time stamps of all events that could affect the biological quality of the specimens by means of RFID tags and readers. Results We developed a pilot study on a fragment of the life cycle, namely the storage between the end of the preanalytics and the beginning of the analytics, which is usually not traced by automated tools because it typically includes manual handling. By adopting RFID devices we identified the possible critical time delays. At 1, 3 and 6 months RFID-tagged specimens cryopreserved at -80°C were successfully read. Conclusions We were able to record detailed information about the storage phases and a fully documented specimen life cycle. This will allow us to promote and tune up the best practices in biobanking because i) it will be possible to classify sample features with a sharper resolution, which allows future utilization of stored material; ii) cost-effective policies can be adopted in processing, storing and selecting specimens; iii) after using each aliquot, we can study the life cycle of the specimen with a possible feedback on the procedures.

An AT-rich region in the APC gene may cause misinterpretation of familial adenomatous polyposis molecular screening†

Familial adenomatous polyposis (FAP) is an autosomal‐dominant condition mainly due to a mutation of the adenomatous polyposis coli (APC) gene. The present study reports evidence of a technical issue occurring during the mutational analysis of APC exon 4. Genetic conventional direct sequence analysis of a repetitive AT‐rich region in the splice acceptor site of APC intron 3 could be misinterpreted as a pathogenetic frameshift result. However, this potential bias may be bypassed adopting a method for random mutagenesis of DNA based on the use of a triphosphate nucleoside analogues mixture. Using this method as a second‐level analysis, we also demonstrated the nonpathogenic nature of the variant in the poly A trait in APC exon 4 region (c.423‐4delA) that do not result in aberrant splicing of APC exons 3–4; conversely, we did not find a previously reported T deletion/insertion polymorphism. Hum Mutat 33:895–898, 2012.

Progesterone receptor gene (PROGINS) polymorphism correlates with late onset of migraine.

Progesterone influences central neuronal excitability, a key event in migraine pathophysiology. Progesterone receptor gene (PGR) rs1042838 (G/T - Val660Leu) variant is indicative of PROGINS haplotype and associated to a reduced PGR activity. With the aim of investigating whether any type of association existed between this genetic variant and migraine pathophysiology, genotyping was performed in 380 consecutive migraine patients and 185 age-, sex-, and race-ethnicity-matched healthy controls from Interinstitutional Multidisciplinary BioBank (BioBIM) of IRCCS San Raffaele Pisana, Rome, Italy. rs1042838 genotypes did not correlate with demographics or clinical migraine features. However, TT (Leu) genotype was significantly associated with a later age of migraine onset: Patients affected by migraine with aura showed a linear relationship between copy number of the T allele carried by the individual and the age of migraine onset. Our data suggest that the PROGINS PGR polymorphism does not directly predispose to migraine but significantly delays migraine onset probably via a reduction in brain neuronal excitability.

Analytical performance evaluation of the new GEM® Premier™ 5000 analyzer in comparison to the GEM® Premier™ 4000 and the RapidPoint® 405 systems

AIM OF THE STUDY Blood gas analysis (BGA) is essential for the diagnosis and management of acid-base imbalances. We evaluated and compared the analytical characteristics of the new GEM® Premier™ 5000 (GP5000) (Instrumentation Laboratory, Bedford, MA, United States) BGA point-of-care (POC) device with those of the GEM® Premier™ 4000 (GP4000) (Instrumentation Laboratory, Bedford, MA, United States) and RapidPoint® 405 (RP405) (Siemens Healthcare, Milan, Italy) POC analyzers. The effect of sample mixing on patient results was also studied. MATERIAL AND METHODS Quantitative measurement of pH, pCO2, pO2, Na+, K+, Cl-, iCa2+, glucose, lactate, tHb, COHb, MetHb, O2Hb, HHb and Hct were carried out. The imprecision study (IS) and method comparison study (MS) were performed according to CLSI EP guidelines, using respectively internal as well as external quality controls (IS) and whole blood samples collected from the routine analysis (MS). RESULTS GP5000 demonstrated satisfactory characteristics in the IS showing comparable (GM4000) or even better (RP405) imprecision results than the routine POC devices. Good performance was observed in the MS both using GP4000 and RP405 as reference instruments. Pre-analytical sample management can heavily affect the accuracy of BGA results. In the specimen mixing evaluation, a significant improvement in results accuracy was observed when mixing procedures were more meticulous. CONCLUSIONS Considering the overall analytical performance observed, the ease of use of the system, the rapid time-to-results and the innovative Intelligent Quality Management technology (iQM2®), GP5000 seems suitable to be used in clinical care for safe patient management. Additionally, effective sample mixing upon draw and before analysis is strongly advisable in order to ensure the most clinically reliable BGA results.