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The human platelet antigens (HPA) are genetically defined polymorphisms expressed on platelet membrane glycoproteins. As platelet antigens are very important in several clinical situations and in population genetics, we used the polymerase chain reaction with sequence-specific primers (PCR-SSP) to investigate HPA-1, -2, -3 and -5 allele frequencies in the Croatian population. The HPA frequencies obtained in 219 Croatians were: 1a–0·854, 1b–0·146, 2a–0·890, 2b–0·110, 3a–0·575, 3b–0·425, 5a–0·895 and 5b–0·105. These data are similar to the frequencies reported in most European studies with some significant differences in HPA-2 when compared with the Dutch and German population, in HPA-3 when compared with the Swiss population and in HPA-5 when compared with the Finnish population. The three most common condensed HPA genotypes in the Croatian population were: HPA-1a/a, -2a/a, -3a/b, -5-a/a (0·283), HPA-1a/a, -2a/a, -3a/a, -5-a/a (0·137) and HPA-1a/b, -2a/a, -3a/b, -5-a/a (0·087). Data obtained in this study can be used for better understanding and treatment of immune-mediated platelet disorders in our population. [ABSTRACT FROM AUTHOR]

Modern photo-optical coagulometers collect optical data in the form of reaction curves and offer a possibility to determine clotting times at different points of clot formation by using different evaluation modes. The objectives of this study were to determine the possible impact of an evaluation mode on activated partial thromboplastin time (APTT) results and to investigate potential benefits from visual inspection of obtained reaction curves. APTT was determined by using actin FS as reagent on two coagulometers (Siemens Medical Solutions) in 174 plasma samples with three different evaluation modes: fixed absorbance (FA), drifting baseline (DB), and point of inflexion (POI) on Behring coagulation timer (BCT), and with DB mode on Behring coagulation system (BCS). Statistically significant difference of APTT results applying the Friedman’s test ( P < 0.0001) followed by Dunn’s multiple comparison test ( P < 0.05) was obtained in all tested samples between POI mode and all other evaluation modes, independently of analyzer used. The differences obtained indicated that laboratory professionals must be aware of possible different evaluation modes on different analyzers, and establish evaluation mode-specific reference intervals. Moreover, correctness of a reported result could be confirmed only by visual analysis of the reaction curve. [ABSTRACT FROM AUTHOR]

Abstract: In this study we investigated IgH and TCRγ gene rearrangements, cyclin A1 and HOXA9 gene expression as well as the in vitro growth of biphenotypic acute leukemia (BAL) blasts in relation to acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). The aim of the study was to correlate BAL morphology and its biological parameters in order to get information that might be used for additional stratification of BAL. This rare form of AL was identified in a total of 10 patients, comprising 4.3% of adult and 3.0% of pediatric patients with de novo AL referred to our institution during the 1999–2003 period. Our results indicate that IgH and TCRγ gene rearrangements correlated well with lymphoid BAL morphology, whereas the expression of cyclin A1 correlated with myeloid and undifferentiated BAL morphology. Surprisingly, HOXA9 expression, a marker associated with myeloid cell lineage, showed no strong correlation with BAL morphology. Finally, in vitro growth of blasts during a 7-day culture showed autonomous cell growth in 3/10 AML and 3/8 myeloid BAL samples tested, but not in any of the AL with lymphoid features. Further studies are needed to confirm these findings and to extend research to a broader spectrum of cell markers. [Copyright &y& Elsevier]

Diagnosis of haemophilia A is usually made by the measurement of factor VIII (FVIII) activity that allows categorization of the disease severity. However, tests that assess global haemostasis may better reflect clinical features and give additional clinically relevant information. The aim of this study was to develop a new quantitative activated partial thromboplastin time (aPTT) waveform analysis and compare it with FVIII activities to find out whether waveform parameters are superior determinants of clinical phenotype. A total of 81 haemophilia A patients divided into two groups (37 severe, 44 non-severe) were included in the study. The control group comprised 101 healthy male volunteers. Quantitative aPTT waveform analysis was performed with Actin FS on BCS (Siemens Healthcare Diagnostics, Marburg, Germany) using three parameters (DELTA, RATIO-1, RATIO-2) obtained from a single aPTT measurement with two evaluation modes. FVIII activities were measured by one-stage clotting and two-stage chromogenic assay. Statistically significant difference (P < 0.001) between control group and all haemophilia A patients, as well as between severe and non-severe haemophilia A patients was obtained for all quantitative waveform parameters. Our study revealed parameter DELTA as the best waveform parameter, showing significant correlation with FVIII activities and clinical parameters, and excellent performance for distinguishing between severe and non-severe haemophilia A patients (ROC analysis: sensitivity 97.3%, specificity 93.2%). The results obtained by new quantitative aPTT waveform analysis were superior to those obtained by standard laboratory methods. The simplicity and cost-benefit of the method make this approach a reasonable and promising tool for assessing coagulation in haemophilia A patients. [ABSTRACT FROM AUTHOR]

Pediatric stroke is significantly less common than stroke in adults, but represents a major challenge to public health authorities. The aim of this retrospective study was to identify the total and annual number of children younger than 18 years with arterial ischaemic stroke and transient ischaemic attack referred to the Children's Hospital Zagreb, which is a major national centre specialised for the treatment and prevention of stroke in children. We reviewed the medical records of the Department of Neuropediatrics database at the Children's Hospital Zagreb between 1998–2005 in order to provide demographic and clinical characteristics and neuroimaging findings in children with arterial ischaemic stroke. In the 7-year period, we identified a total of 124 children from different geographic areas of Croatia with a confirmed diagnosis of transient ischaemic attack ( N=77), and arterial ischaemic stroke ( N=47). Perinatal and childhood arterial ischaemic stroke were equally represented (23 and 24 children, respectively). The average number of new cases identified each year was 18 cases (range: 12–21), seven arterial ischaemic stroke and 11 transient ischaemic attack cases. Male predominance was found in children with arterial ischaemic stroke with a male : female ratio of 1·76 : 1, and was slightly higher in childhood arterial ischaemic stroke compared with perinatal arterial ischaemic stroke (2 : 1 and 1·56 : 1, respectively). In contrast, transient ischaemic attack was more frequently found in girls, and more likely identified in older children compared with younger children with arterial ischaemic stroke. Obtained data will contribute to better understanding of paediatric stroke in Croatia and will provide a base for the establishment of the national referral center and national pediatric stroke registry. [ABSTRACT FROM AUTHOR]

ACL TOP is a fully automated coagulation analyzer, designed for simultaneous measurement of routine and special coagulation parameters. We evaluated analytical and technical performance characteristics of the coagulation system composed of the ACL TOP analyzer and HemosIL reagent group for the determination of routine clotting (PT, APTT, fibrinogen, FVII, and FVIII), chromogenic (protein C) and immunological assays (FXIII antigen). Within run and between run CVs ranged from 0.9% to 7.7% and from 2.0% to 14.8% respectively. The obtained CVs for imprecision of calibration curves were <5% for PT and <7% for fibrinogen. The method comparison study showed good correlation between results obtained on the ACL TOP and BCS/BCT analyzers, with correlation co-efficients ranging from 0.709 to 0.955, but with significantly different results for PT INR, APTT, fibrinogen and protein C, and wide dispersion of differences observed in difference plots for most assays. Despite good correlation and agreement for FVIII, problems in measuring FVIII<10% were encountered. The effective throughput for the ACL TOP and BCS was 151 and 212 PT/APTT/fibrinogen tests per hour, respectively. Although the ACL TOP is designed to run multiple assays on a large number of samples, software limitations make the instrument suitable rather for mid-sized laboratories. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of this study was to investigate the prevalence and possible association of inherited prothrombotic risk factors in children with stroke, transient ischemic attack, or migraine. METHODS: We performed genotypic analysis for factor V G1691A, factor II G20210A, methylenetetrahydrofolate reductase C677T, and 4 common platelet glycoprotein polymorphisms (human platelet alloantigen-1, -2, -3, and -5) in 150 children <18 years of age with established diagnoses of stroke, transient ischemic attack, or migraine. Children were classified into 5 groups, namely, childhood arterial ischemic stroke (N = 33), perinatal arterial ischemic stroke (N = 26), hemorrhagic stroke (N = 20), transient ischemic attack (N = 36), and migraine (N = 35). The control group consisted of 112 children < or =18 years of age from the same geographical region who had no history of neurologic or thromboembolic diseases. RESULTS: Heterozygosity for factor V G1691A was associated with approximately sevenfold increased risk for arterial ischemic stroke, perinatal arterial ischemic stroke, and transient ischemic attack. Increased risk for transient ischemic attack was found in carriers of the human platelet alloantigen-2b allele, human platelet alloantigen-5a/b genotype, and combined human platelet alloantigen-2b and human platelet alloantigen-5b genotype. The presence of the human platelet alloantigen-2b allele was associated with a 2.23-fold increased risk for migraine, whereas carriers of the human platelet alloantigen-3b allele had a lower risk for arterial ischemic stroke than did carriers of the human platelet alloantigen-3a allele. CONCLUSIONS: Factor V G1691A has an important role in susceptibility to arterial ischemic stroke, both in the perinatal/neonatal period and in childhood, as well as transient ischemic attacks. A minor impact of human platelet alloantigen polymorphisms suggests that platelet glycoprotein polymorphisms may increase the risk of transient ischemic attacks and migraine, but this should be confirmed in larger studies. [ABSTRACT FROM AUTHOR]