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ObjectivesTo evaluate the stability of complete blood count (CBC) parameters by measuring at multiple time points up to 72 h after venepuncture.Methods36 samples submitted for routine haematology were measured at 0, 8, 24, 48, 72 h. 18 samples were kept at room temperature (23–25 °C) and the other 18 at 4 °C. The stability of the CBC parameters was determined by comparing the results to the 0 h sample. White Blood Cell Count (WBC), Hemoglobin (Hb) concentration, Red Blood Cell (RBC) count, Hematocrit (Hct), Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Hemoglobin Concentration (MCHC), Cellular Hemoglobin Concentration Mean (CHCM), Mean Platelet Volume (MPV), RBC distribution width (RDW), Platelet (PLT) and Reticulocyte counts were studied.ResultsMost parameters were stable for 24 h at 4 °C, except for MCV, MCHC, CHCM and MPV. MCV and MPV increased after 8 h (p<0.0001), whereas MCHC and CHCM decreased significantly after 8 h. Significant changes were found for MCHC in samples kept at 4 °C for 48 h (p=0.002), and for CHCM kept for 72 h (p<0.001). Reticulocyte count stability was maintained for 24 h at 4 °C (p=0.3047). In samples kept at room temperature changes occurred after 8 h in RBC, Hct, MCV, MCH, MCHC, CHCM, MPV and PLT.ConclusionCBC measurements are reliable for 8 h when samples are stored at room temperature. The only parameter stable for 72 h at room temperature was Hb. Blood samples kept at 4 °C for up to 24 h are suitable for haematological analysis.

Under carbon starvation, Aspergillus nidulans released a metallo-proteinase with activities comparable to those of PrtA, the major extracellular serine proteinase of the fungus. The relative molar mass of the enzyme was 19 kDa as determined with both denaturing and renaturing SDS PAGE, while its isoelectric point and pH and temperature optima were 8.6, 5.5 and 65 degrees C, respectively. The enzyme was stable at pH 3.5-10.5 and was still active at 95 degrees C in the presence of azocasein substrate. MALDI-TOF MS analysis demonstrated that the proteinase was encoded by the pepJ gene (locus ID AN7962.3), and showed high similarity to deuterolysin from Aspergillus oryzae. The size of the mature enzyme, its EDTA sensitivity and heat stability also supported the view that A. nidulans PepJ is a deuterolysin-type metallo-proteinase.

The effects of pyrethroid pesticides (deltamethrin, permethrin and cypermethrin) and an organophosphate ester (methidation) on the activities of carp trypsin, alpha-chymotrypsin, carboxypeptidase A and lipase were studied. The enzymes were isolated from the gastrointestinal tract and the effects of the pesticides were investigated during incubation for 5 min. The activity of trypsin was influenced only slightly by the presence of deltamethrin and methidation, whereas permethrin and cypermethrin caused significant inhibition. The pyrethroid pesticides at lower concentrations resulted in a slight activation of alpha-chymotrypsin. Methidation inhibited the alpha-chymotrypsin activity by about 20%. These pesticides modified the lipase activity to a lesser extent; the highest inhibition was measured with cypermethrin. The carboxypeptidase A activity was inhibited by both pyrethroid pesticides and methidation. The results suggest that these pesticides might interact with the active conformation of the studied hydrolytic enzymes, resulting in changes in their activities.

The effects of haevy metals (Cd 2+ , Cu 2+ , Pb 2+ and Zn 2+ ) on activities of carp trypsin, α-chymotrypsin, carboxypeptidase A and lipase were studied. The enzymes were isolated from the gastrointestinal tract and the effects of metal ions were investigated during incubation for 5 min. The presence of Cd 2+ did not influence the activities of CPA and trypsin and 10-20 % inhibiton was observed with α-chymotrypsin and lipase. Cu 2+ only slightly influenced the trypsin and lipase activities, whereas the α-chymotrypsin activity was decreased. All enzyme activities decreased at higher Zn 2+ concentrations. The inhibition was most pronounced at α-chymotrypsin (more than 50%). With the exception of trypsin, Pb 2+ inhibited the activities of the investigated enzymes.