Yuji Imafuku

Endothelin-1 production by human synoviocytes

Immunoreactive (ir)-endothelin (ET)-l concentrations in serum samples and synovial fluids from patients with rheumatoid arthritis were higher than concentrations in sera obtained from healthy volunteers. No significant difference in ir-ET-1 concentrations in synovial fluid was observed between rheumatoid arthritis patients and osteoarthritis patients. Cultured fluids of synovial cells collected from synovial tissues and leucocytes from synovial fluids of rheumatoid arthritis patients were studied to determine the origin of ir-ET-1 in synovial fluids. Ir-ET-1 was detected in the cultured fluids of synovial macrophage-like type A cells, but not in those of fibroblast-like type B cells from the synovial tissues or leucocytes from the synovial fluids. Longitudinal studies showed that the ir-ET-1 concentration in the cultured fluid reached a peak around 24 h after starting the culture. ET-1 secreted from macrophage-like synoviocytes may be involved in the pathogenesis of inflammatory arthritis.

The effect of EDTA contaminated in sera on laboratory data.

BACKGROUND We report two cases in which the data marked by low levels of serum iron (Fe) (negative value), low levels of serum calcium (Ca) and high levels of serum potassium (K) were inconsistent with their clinical states. Re-examination within 1 day showed that all the data were within or close to the reference intervals. These results could suggest contamination of ethylene diamine tetraacetate-dipotassium salt (K(2)EDTA) used in the blood collection tube for peripheral blood cell count in the tube for the serum. One of the mechanisms was suspected to be due to the backflow of evacuated blood mixed with K(2)EDTA into serum tube. MATERIALS AND METHODS To analyze the influence of EDTA on routine and nonroutine laboratory tests, we performed routine examination using serum and EDTA plasma from healthy volunteers. RESULTS We found a definite effect on iron, calcium and potassium and alkaline phosphatase, zinc sulfate turbidity test, ammonia, leucine aminopeptidase and CH50. We also found a definite effects on copper, angiotensin-converting enzyme (ACE), matrix metalloproteinase (MMP)-1, -3 and -9, tissue inhibitor of matrix metalloproteinase (TIMP)-1, hepatocyte growth factor (HGF), monoamine oxidase (MAO), vitamin B(12), ACTH and IL-6, though the mechanisms were not clear. CONCLUSIONS Inappropriate blood collection can induced false biochemical data due to the contamination of EDTA.

Matrix effects in clinical immunoassays and the effect of preheating and cooling analytical samples

Abstract Immunological reactions are influenced by various factors including antigens, antibodies and other variables. We focused on two items: i) matrix effects, especially of detergents and ii) temperature effects: preheating sera, especially effects on rheumatoid factor (RF) measurement and false-positive reactions in ELISAs, and cold storage of sera, especially effects on complement. Among various additives, detergents affected the agglutination reaction for fecal hemoglobin and hepatitis B surface (HBs) antigen. Some of the detergents examined abolished these antigenicities, however, polyethylenglycols enhanced the reactions. Heat-inactivation of sera at 56°C for 30 min was employed in serological testing. However, in RF measurement, 10 min of preheating was sufficient to abolish C1q (subcomponent of C1), which could participate in the agglutination reaction. In ELISA for antibodies, false-positive reactions were caused by preheating sera. By the analyses of assays for antibodies to hepatitis C virus (HCV) and cardiolipin, it was found that they were induced by immunoglobulin G (IgG) modified by preheating. Cold storage induced activation of complement (cold activation) in anti-HCV antibody positive sera. CH50 titers in the sera were lowered by one cycle of freezing at −20°C and thawing, and the decrease was affected by the containers.

Efficacy of 1.0% chlorhexidine-gluconate ethanol compared with 10% povidone-iodine for long-term central venous catheter care in hematology departments: a prospective study.

The efficacy of 1% chlorhexidine-gluconate ethanol and 10% povidone-iodine for skin antisepsis of central venous catheter (CVC) sites were compared among hematology patients. The CVC site colonization rates of those groups were 11.9% and 29.2%, respectively, and the catheter-associated blood stream infections were 0.75 and 3.62 per 1,000 catheter-days, respectively. One percent chlorhexidine-gluconate ethanol was superior to povidone-iodine to reduce skin colonizers at CVC sites even when catheters were used for long duration.

Identification of a dysfibrinogenemia of γR275C (Fibrinogen Fukushima)

Abstract Background : Various dysfibrinogenemias have been identified worldwide. This paper describes a case of dysfibrinogenemia recently identified in our laboratory. Patient : A 34-year-old pregnant woman without any clinical complaints was admitted to our hospital for delivery. She had an extremely low fibrinogen concentration as determined by the thrombin time method though immunoassay showed a titer within the reference range. Dysfibrinogenemia was suspected and further analyses were performed including on her family. Thrombin time was measured using human and bovine thrombin with and without calcium ion. Reptilase time was also measured. To identify the genetic mutation responsible for this dysfibrinogen, genomic DNA extracted from the blood was analyzed for mutation-rich regions in the fibrinogen gene. Results : The subject, her mother and her two infants showed the same pattern of results while her father showed a regular pattern. Thrombin time calculated using both human and bovine thrombin and reptilase time was elongated in the propositus. The extent of the elongation was decreased in the presence of calcium ion. DNA sequencing showed heterogeneous fibrinogen γR275C mutations in the propositus, mother and two children. The father showed no mutation. Conclusions : A case of dysfibrinogenemia γR275C without any clinical symptoms was found by routine coagulation testing and was genetically identified.

Determination of potassium flux activity of viable human erythrocytes by measuring the release-influx ratio

A simple and convenient method to determine the K+-flux activity of viable human erythrocytes was developed. Erythrocyte suspensions were incubated at 4 degrees C for 24 h to induce K+-release (deltaKr) and then at 37 degrees C for 3 h to influx K+ into erythrocytes (deltaKi). A straight-line relationship between K+ release-influx ratio and ouabain-induced K+-efflux from erythrocytes indicated that deltaKi/deltaKr ratio or the K+-flux activity was reflected predominantly by Na+/K+-exchanging ATPase activity. Using this method, K+-flux activity of erythrocytes in the young and the aged subjects was measured. The mean deltaKi/deltaKr ratio of the aged subjects was decreased significantly. This method of measuring deltaKi/deltaKr ratio is useful for the evaluation of K+-flux activity of viable erythrocytes.