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Background The aim of the present work was to characterize the molecular defects of a slow-migrating (albumin Zagreb) and a fast-migrating (albumin Krapina) genetic variant of human serum albumin detected in heterozygous persons living in Croatia and to elucidate the fatty acid-binding properties of the two alloalbumins. Methods Purification and structural identification of the variants were performed by conventional protein chemistry methods, whereas types and amounts of albumin-bound, endogenous fatty acids were determined by gas chromatography. Results Protein sequencing established that albumin Zagreb is a proalbumin variant (−1Arg→Gln), and that albumin Krapina is due to a mutation within the mature polypeptide chain (573Lys→Glu). The gas chromatographic results showed that the fatty acid-binding properties of the proalbumin variant are normal, while the amino acid substitution in position 573 resulted in a general decrease of fatty acid binding. Conclusions The structural defects of the first alloalbumins, detected by routine clinical electrophoresis among the Croatian population, were characterized. Albumin Zagreb is caused by a hot-spot mutation occurring in a CpG sequence in the albumin gene. It is commonly assumed that bisalbuminaemia has no direct clinical relevance. However, the present study suggests that naturally occurring mutations can affect the ligand-binding properties of human serum albumin.

Cilj: ispitati kvalitetu digitaliziranih slika u svrhu elektronskog dopisivanja. Materijal: Slika izoelektričnog fokusiranja serumskih proteina u pacijenta sa sporom inačicom albumina Zagreb i slika krvnog razmaza komprimirane su u osam različitih stupnjeva kompresije (3 bpp, 1.5 bpp, 1 bpp, 0.7 bpp, 0.5 bpp, 0.3 bpp, 0.2 bpp i 0.1 bpp) primjenom JPEG i JPEG2000 kompresijskih algoritama. Kvaliteta slika procijenjena je subjektivno - medicinski biokemičari ocjenjivali su kvalitetu slika kao loša (potpuna dekompozicija slike), dobra (vidljive promjene kvalitete slike) i izvrsna (vrlo velika razlučivost) te objektivnim mjerama (PSNR, SNR i MSE). Rezultati: Medicinski biokemičari ocijenili su sve kompresije JPEG 2000 izvrsnima. Protivno, JPEG-kompresijom pri kompresijama ≤ 0.2 bpp dobile su se slike loše kvalitete. Objektivne mjere kvalitete slike potvrdile su da se pri JPEG-kompresiji, stupnja kompresije ≤ 0.2 bpp, nisu dobile slike zadovoljavajuće razlučivosti. Slike s vrijednostima PSNR ≥ 40, 0 bpp, SNR ≥ 25, 5 bpp, OQF ≥ 31, 0 i MSE ≤ 6.5 subjektivno su bile jednako kvalitetne kao i izvorne, nekomprimirane slike. Zaključak: Algoritam JPEG2000 pokazao se boljim nego JPEG.