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Riitta Kekomäki

Publications and source records attributed to Riitta Kekomäki.

10 recordsLinked to original sources
PubMed2006

Multiple-laboratory comparison of in vitro assays utilized to characterize hematopoietic cells in cord blood.

BACKGROUND: Understanding the variability in results obtained by multiple laboratories is important because cord blood units are distributed worldwide for transplantation. STUDY DESIGN AND METHODS: Four exercises were conducted by multiple laboratories to assess assay variability on nucleated cell (NC), mononuclear cell (MNC) by hematology analyzers [HAs], and CD34+ cell (flow cytometry) measurements. Exercise 1 was an intralaboratory exercise in which the reproducibility of cell measurements was determined. Exercises 2 and 3 involved the shipment of identical processed cord blood samples. In Exercise 2, laboratory-specific methods were utilized. In Exercise 3, two commercial CD34+ cell methods (Stem-Kit and TruCOUNT) were used. In Exercise 4, CD34+ cell levels were determined on repetitive regating of identical list-mode files. RESULTS: Intralaboratory reproducibility was highest for NC measurements and lowest for CD34+ cell measurements. In Exercise 2, all laboratories except one utilized HA with an impedance technology and determined comparable results for NC and MNC levels, whereas the other laboratory utilized a HA with an optical counting method. Substantial variation was observed on measuring CD34+ cells with ranges of 32 to 141, 32 to 66, and 25 to 116 CD34+ cells per microL for the three identical samples. In Exercise 3, on the use of one specific commercial assay, the ranges of CD34+ levels were 214 to 411 and 62 to 178 cells per microL for the two identical samples. Nearly all participating laboratories determined comparable CD34+ levels on the use of identical list-mode files. CONCLUSION: These studies indicate that substantial variability in CD34+ cell levels were determined with flow cytometry. The variability in NC and MNC levels was minimal with HA methodology.

Antigens, CD↗
PubMed2006

Variation of platelet production and discard rates in 17 blood centers representing 10 European countries from 2000 to 2002.

BACKGROUND: New blood safety regulations raise costs and pressure blood centers to improve their efficiency. Evaluation of platelet (PLT) production and discards between centers of different size and nationality may provide a basis for more efficient PLT inventory management. STUDY DESIGN AND METHODS: Data were gathered retrospectively for 2000 to 2002 from 17 blood centers in 10 European countries. The descriptive analyses comprised evaluation of PLT production methods and volumes. Discard rates were surveyed also for 2003 to 2004. The number of cellular blood components produced per working hour was expressed as an arbitrary labor index. RESULTS: Seven hospital blood banks and 10 centers with other administrative systems participated in the study. Buffy coat (BC) and apheresis PLTs were used by all centers except two preparing all PLTs by apheresis. In 2002, 73 percent of all PLTs were produced by the BC method, and PLTs were utilized from 41 percent of whole-blood donations. One center also produced PLTs by the PLT-rich plasma method. Mean annual production volume of PLTs varied greatly, from 3,345 to 103,643 units, with an increase of 5.6 percent from 2000 to 2002. Three-year mean discard rates varied between 6.7 and 25 percent, and yearly mean discard rates remained at 13 percent in 2000 to 2002 and also in 2003 to 2004. Arbitrary labor index varied from 2.4 to 7.3 between centers. CONCLUSIONS: PLT discard rates were relatively high in the European blood centers. Detailed information on specific causes for high discard rates would help improve the efficiency of PLT management, because blood centers cannot regulate demand. Use of labor resources in component preparation also remains an important target for further research.

Blood Banks↗
PubMed2006

International comparison of the technical efficiency of component preparation.

BACKGROUND: Under economical constraints, blood centers need to identify ways to improve their efficiency. Because there is little evidence regarding the technical efficiency of blood centers, international comparisons may be useful in identifying efficiency discrepancies and can reveal opportunities for enhancing efficiency, such as allocating resources more effectively. STUDY DESIGN AND METHODS: Data were collected for years 2000 through 2002 from 16 blood centers in 10 European countries. Input variables included working hours, whole-blood (WB) collections, premises, and equipment, and the output variables were red blood cells and platelets (PLTs). A nonparametric method, data envelopment analysis (DEA), was used in the analyses of technical efficiency in blood component preparation departments. Efficiency scores were calculated with DEA linear programming techniques and evaluated for site characteristics that possibly affect efficiency, such as the production method of PLTs and the proportion of BCs (buffy coats) from WB and BC PLTs from all PLTs produced. RESULTS: With working hours and equipment as inputs, median technical efficiency was 60 percent (range, 41%-100%). Four departments were efficient (efficiency, > 90%), and 12 were inefficient (range, 41-89). Efficiency remained roughly the same in 13 departments through the 3-year study period and decreased in 3. Efficiency was mainly affected by staffing levels (working hours). Efficiency did not directly relate to production volume, method, or any other site characteristic. CONCLUSIONS: The major cause of inefficiency was excess staffing resulting from a suboptimal combination of manpower and production output levels. Further research is needed to manage factors affecting efficiency, such as the fluctuation of demand in production planning.

Blood Banks↗
PubMed2005

Cord blood hematopoietic progenitor cell concentration and infant sex.

BACKGROUND: Characterization of cord blood facilitates understanding of the factors affecting cord blood transplant quality and improvement of transplantation results. Cord blood obtained from male and female infants has not been thoroughly characterized. STUDY DESIGN AND METHODS: A study was performed to test the hypothesis that the cord blood hematopoietic progenitor cell content-of which the CD34+ cell and colony-forming unit (CFU) concentrations were taken as markers-would not only associate with birth weight but also with sex. The hematopoietic progenitor cell concentrations of 1999 healthy infants (47% female) were analyzed in a cord blood bank setting. RESULTS: Male infants had significantly higher median CD34+ cell concentrations than female infants (31.8/microL vs. 30.2/microL, respectively; p = 0.03). Although the disparity in absolute concentrations was small, it was 5.3 percent. In CFU subgroup analysis, the median CFU-mixed concentration of male infants (11.1/microL) was higher than in female infants (9.9/microL; p = 0.03). The difference was more pronounced when cumulative frequencies of the CFU-mixed concentrations from cesarean section deliveries were compared. In multivariate linear regression analysis, the positive influence of male sex on the CD34+ cell concentration was significant (p < 0.05). The expected higher median nucleated cell concentration of female compared to male infants (13.9 x 10(9)/L vs. 13.3 x 10(9)/L, respectively; p = 0.0001) was mainly due to the higher neutrophil concentration of female infants (7.1 x 10(9)/L vs. 6.5 x 10(9)/L, respectively, p < 0.0001). CONCLUSION: Cord blood hematopoietic progenitor cell concentration was higher in male infants, even after correcting for birth weight. Sex may affect the hematopoietic potential of cord blood transplants.

Antigens, CD34↗
PubMed2005

Soluble glycoprotein V as a quality marker of platelet concentrates stressed by transportation.

BACKGROUND: Despite ongoing improvements in storage conditions for platelet concentrates (PCs) for clinical use, leukoreduced platelets (PLTs) undergo subtle changes that are partly due to PLT activation. As PLTs are activated, the expression of P-selectin (CD62P) increases, and soluble glycoprotein V (sGPV) is released. GPV, part of the GPIbIXV complex, has been suggested as a marker of PLT activation. STUDY DESIGN AND METHODS: An array of assays, used for quality control of PCs, was performed and the results were compared. The tests included PLT count, swirling, mean PLT volume, extent of shape change (ESC), hypotonic shock response (HSR), CD62P, lysosomal membrane protein (CD63), sGPV, and the metabolic tests (pH, pO(2), pCO(2), lactate, glucose). The performance of the assays was evaluated during the storage period by comparing buffy coat-derived PCs (24 PCs of 4 units) stored on flatbed agitator or stressed twice by overnight transportation. RESULTS: The repeatability of all tests was good. ESC and HSR correlated with each other (r = 0.559). Importantly, there were also associations between sGPV and ESC (r = -0.564) and HSR (r = -0.389). The correlations of sGPV with lactate and glucose concentrations and with expression of CD62P and CD63 were also good. No significant changes were induced by two overnight transportations. CONCLUSION: sGPV might be applicable for statistical process control of the quality of PCs, in addition to metabolic tests. It may also be helpful in analyzing potential improvements in blood component processing. Repeat transportation of PCs may cause minimal changes on PLT in vitro properties, if any.

Biomarkers↗
PubMed2005

Intraventricular haemorrhage in very-low-birthweight preterm infants: association with low prothrombin activity at birth.

AIM: To determine the occurrence of intraventricular haemorrhage (IVH) and its association with coagulation factors at birth in preterm neonates born before 30 wk gestation. METHODS: 38 neonates (median gestational age 27 wk, range 24-29 wk; median birthweight (BW) 933 g, range 515-1760 g) admitted to the neonatal intensive care unit were studied. Blood samples for coagulation factors were taken within 2 h after birth. The first cranial ultrasonographic examination was performed within the first 3 d. The occurrence of IVH was tested statistically by the Mann-Whitney U-test for association with the activity of coagulation factors and clinical variables. RESULTS: Thirteen IVHs occurred within the first 3 d of life. IVH was associated with BW <1000 g (p=0.012), low mean blood pressure within the first 2 d (p=0.026), gestational age <27 wk (p=0.054), low Apgar scores (<7) at 1 min (p=0.078) and intrauterine growth restriction (p=0.072). At birth (samples drawn with a median of first 36 min of life), infants with subsequent IVH had statistically significantly lower prothrombin (factor II) activity (p=0.024) than infants without IVH. CONCLUSION: The measured low prothrombin may have been affected by a prior bleeding event. Nevertheless, preterm infants with low prothrombin activity may be susceptible to IVH, or to the progression of it, if left undiagnosed.

Cerebral Hemorrhage↗
PubMed2004

The predictive value of megakaryocytic and erythroid colony formation and platelet function tests on the risk of thromboembolic and bleeding complications in essential thrombocythaemia.

The predictive value of spontaneous in vitro colony formation of megakaryocytic and erythroid progenitors (154 patients), and defective platelet aggregation responses (55 patients) on the risk of thrombohaemorrhagic complications in patients with essential thrombocythaemia (ET) was evaluated retrospectively. In the in vitro cultures of haematopoietic progenitors, 114/154 patients (74%) showed either spontaneous megakaryocytic or erythroid colony formation or both. Forty-three per cent of patients with any spontaneous colony growth and only 20% of those without this phenomenon had an arterial thrombosis at diagnosis or during the follow-up (P = 0.02). In the whole patient group neither spontaneous megakaryocytic nor spontaneous erythroid colony formation alone predicted the risk of arterial thrombosis. In patients younger than 45 yr of age, the prognostic value of spontaneous megakaryocytic growth was statistically significant: 44% of the patients with spontaneous megakaryocytic colony formation, but only 14% of those without it, experienced arterial thrombosis (P = 0.04). The presence of spontaneous colony formation had no effect on the risk of bleeding complications. Forty-one of the 55 patients (75%) showed abnormalities in the platelet aggregation responses. There was no statistically significant correlation between the platelet function response and the risk of bleeding or thrombotic complications. No correlation was found between the platelet aggregation responses and the presence of spontaneous colony growth. In conclusion, spontaneous colony formation indicated an increased risk of thrombohaemorragic events but the platelet function test had no predictive value for these complications.

Adult↗
PubMed2004

Development of selected coagulation factors and anticoagulants in preterm infants by the age of six months.

The development of the coagulation and anticoagulation system in preterm infants was assessed, with special emphasis on extremely low birth weight (ELBW) infants and haemorrhagic or other complications after birth. Coagulation factors II (prothrombin), V (FV), VII (FVII) and X (FX) were analysed at birth and at a corrected age of six months. In addition, antithrombin (AT), protein C (PC) and protein S (PS) were measured at six months, and DNA samples were tested for Factor V Leiden (R506Q). Eighty-two infants, with a median gestational age (GA) of 32 weeks (range 24-36) and a median birth weight of 1562 g (range 695-3520), were studied. Fifteen of these were ELBW infants (range 695-1000g). Prothrombin, FV, FVII and FX reached healthy term six-month-old infant activity levels. Prothrombin and FX did not reach adult values; median activity levels remained at 82% and 78%, respectively. During the follow up, the FV and FVII levels of the ELBW infants (GA 24-27 weeks) increased more than those of the preterm infants born with higher GA (p < 0.001). At birth, prothrombin correlated significantly with FV, FVII and FX (p < 0.001). FVII at birth and at six months correlated significantly with PC (p = 0.021 and p = 0.009, respectively). These findings indicate that the gain in the coagulation factor concentrations in infancy is greatest in infants with the lowest GA at birth. Interesting new inter-relations of coagulation factor and physiological anticoagulant levels may indicate that there are still unrecognised pathways in the function of newborn haemostasis.

Age Factors↗
PubMed2003

Platelet function and immune response.

Altered platelet function may cause abnormal bleeding tendency or thrombosis. The goal of this article is to provide insights for understanding how platelet functions are related to immune response. Autoantibodies and drug-induced platelet antibodies have been demonstrated to downregulate or enhance platelet function. Drug-induced immune thrombocytopenia is an important adverse effect of glycoprotein IIb/IIIa antagonists. Platelets respond to binding of glycoprotein IIb/IIIa by partial platelet activation. This includes conformational changes of glycoprotein IIb/IIIa. Membrane changes may expose immunogenic neoantigens capable of abnormally altering immune responses. The presence of drug-dependent antibodies in an unexpectedly high frequency compared with the frequency of overt thrombocytopenia has opened a model for further studies. These may include monitoring of antiplatelet immune responses when new platelet antagonists are developed and comparisons of specific immune responses in other acute thrombocytopenias, such as those induced by quinidine or heparin and that associated with gold therapy or in acute profound thrombocytopenia, which may follow vaccination with live attenuated viruses.

Autoantibodies↗