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Biomedical subjects

K Koerner

Publications and source records attributed to K Koerner.

71 records · Page 4Linked to original sources
PubMed1987

[Collection of thrombocyte concentrates and coagulation active fresh plasma with the Haemonetics PCS system].

More intensive chemotherapeutic regimens in patients with leukemia or malignant disease lead to an increasing demand for platelet concentrates. As conventional preparation of platelets from fresh whole blood is limited by the number of blood donors, new methods have to be investigated. Plasmapheresis with simultaneous collection of platelets is favored. We tested the new Haemonetics PCS system (Haemonetics Corp., Braintree, Mass.). Beside the effectivity of the measure, we were interested in the quality of the products. The simultaneous collection of hemostatic active plasma and platelet concentrates did not produce the same quality as our routine products.

Adult↗
PubMed1986

In vitro effect on stored red blood cells and platelets after a 15-hour delayed refrigeration of whole blood prior to component preparation in CPD-AD.

We extended the time of keeping whole blood at 20-24 degrees C to 15 h (overnight) after phlebotomy for preparing platelet concentrates. We have evaluated the in vitro characteristics of platelets and blood cells prepared from whole blood drawn into CPD-AD, an anticoagulant containing 0.4 mM adenine and 1.5 times more dextrose than CPD. We studied in vitro red cell and platelet function of blood cooled either within 4 h after collection or after a 15-hour delay. In vitro platelet function measured as hypotonic shock reaction, aggregation response to ADP and collagen and 14C-serotonin uptake were not significantly different after preparation and after a 5-day storage period. Units held at room temperature for 15 h after blood collection exhibited a level of 2,3-DPG that was 45% of that exhibited by red cells held for 15 h at 1-6 degrees C. All other in vitro parameters of red cell concentrates measured during 35 days of storage were not significantly different. Based on these in vitro data blood drawn into CPD-AD might be kept up to 15 h at room temperature prior to refrigeration in order to prepare platelet concentrates.

2,3-Diphosphoglycerate↗
PubMed1984

Platelet function of room temperature platelet concentrates stored in a new plastic material with high gas permeability.

In vitro platelet function during 7 days of storage at room temperature was studied in a conventional polyvinylchloride plastic bag F 76 and in a new plastic bag F 702 which contained as plasticizer a phtalateester analogue. This new material has increased permeability to oxygen and carbon dioxide, and therefore a pH decrease does not occur during 7 days of platelet storage. The decrease of plasma glucose concentration and the increase of plasma lactate in the new bag is less than in the standard plastic currently in use. In vitro platelet function measured as hypotonic shock reaction, aggregation response to ADP and collagen and 14C-serotonine uptake was better than that found with the standard material. The data indicate that the use of the new platelet storage container F702 will permit satisfactory storage for at least 5 days at 22 degrees C. It is suggested that it will even improve the quality, as measured by in vitro tests, of platelets stored up to 72 h compared to the standard plastic.

Blood Platelets↗
PubMed1984

[Stability of blood coagulation factors in deep frozen fresh plasma by storage at -20 degrees C and -40 degrees C].

Fresh frozen plasma (FFP), was shock-frozen to -25 degrees C within six hours after blood donation. The platelet count was reduced to 20 000/mm3. Aliquots were stored at -20 degrees C and -40 degrees C up to 24 months. Quick, PTT, factor V, VIII, IX, thrombin, antithrombin III, plasminogen, plasma-prekallikrein and kallikrein were determined monthly. With respect to the parameters investigated there was no significant difference between storage at -20 degrees C and -40 degrees C. Factor VIII loss was 10% after 12 months of storage. The activity of factor IX and V remained unchanged during 12 months, then factor V increased during storage. The other parameters did not change. Our study indicates quality of FFP seems not primarily depend on storage temperature, but an optimal preparation technique is much more important.

Blood Coagulation Factors↗
PubMed1983

Platelet function after shipment of room temperature platelet concentrates.

Platelet concentrates stored for 48 or 72 h were shipped up to 10 h at 22 or 4 degrees C. Thereafter platelet function was compared with platelet concentrates stored under optimal blood bank conditions with continuous agitation and strict temperature control. Platelet function measured by hypotonic shock response, aggregation and serotonin uptake is better maintained at 22 than at 4 degrees C. The only difference between shipping and continuous agitation is seen in the hypotonic shock response after a total storage time of 72 h. Shipped platelets showed a marked drop in hypotonic-shock response. The data indicate that shipment of platelet concentrates does not significantly impair platelet function.

Blood Platelets↗
PubMed1981

[Deep frozen fresh plasma in blood component therapy: preparation--quality control--indications].

Fresh frozen plasma is prepared within 6 hrs after collection in a double bag system. A second centrifugation at 4600 x g is necessary to obtain a platelet poor plasma. A special bag freezing system fitted to a conventional cryostat and cooled with ethanol to -50 degrees C was developed to reach the required cooling rate. It is possible to freeze 25 plasma bags simultaneously within 30 min in this new apparatus. Fresh frozen plasma prepared in this manner contains all coagulation factors and inhibitors with almost normal activities. Freezing at -40 degrees C in the air, prolonged storage of the starting material, or insufficient cooling of the frozen product deteriorate its quality. The influence of these variables with the discussed in detail. Indications of fresh frozen plasma, especially for dilution- and posttraumatic consumption coagulopathy as well as liver disease, are presented.

Blood Preservation↗
PubMed1978

[Microaggregates in stored blood: comparative evaluation of whole blood and buffycoat-free red cell concentrates (author's transl)].

Routine preparation of red cell concentrates in our institute removes 90% of platelets and 70% of leucocytes in whole blood. Microaggregate formation in whole blood and red cell concentrates was comparatively evaluated by blood passage through a membrane filter with a pore size of 12 micron. Dry weight residues on the filter due to microaggregates were 5 to 10 times lower in red cell concentrates as compared to whole blood at any point of a 20 day storage period. In addition, the decrease in flow rate with increasing storage time was much more marked for whole blood than for red cell concentrates.

Adult↗
PubMed1975

Purification of biosynthetic threonine deaminase from Escherichia coli.

Biosynthetic threonine deaminase (L-threonine hydro-lyase (deaminating), EC 4.2.1.16) was purified to apparent homogeneity from cell extracts of Escherichia coli by chromatographic procedures using valine-Sepharose, isoleucine-N-hexamethyleneamine-Sepharose, and hydroxyapatite with an overall yield of 40%. Analytical ultracentrifugation shows a molecular weight of 214 000. In sodium dodecyl sulfate gel electrophoresis, the enzyme migrates as a single band corresponding to a molecular weight of about 50 000. These data confirm that the enzyme is a tetramer. The sedimentation coefficient, s-020,w, determined by differential sedimentation experiments is 9.2 S. The enzyme shows absorption maxima at 415 and 280 nm. Determination of pyridoxal phosphate by three indenpendent methods shows the presence of two molecules of pyridoxal phosphate per enzyme molecule, the different methods being in excellent agreement equilibrium dialysis experiments establish the presence of two isoleucine binding sites. The Scatchard plot suggests non-cooperativity of these sites. The association constant for isoleucine is 1.2 - 10(5)M-1.

Binding Sites↗
PubMedDate not supplied

Low cytokine contamination in buffy coat-derived platelet concentrates without filtration.

BACKGROUND: Cytokines (interleukin [IL]-1 beta, IL-6, and tumor necrosis factor [TNF]) generated by white cells during the storage of platelet concentrates can cause febrile nonhemolytic transfusion reactions. The high rate of febrile reactions reported in other studies was not observed in the patients in the authors' center. This discrepancy prompted the determination of cytokine levels in buffy coat-derived platelet concentrates. STUDY DESIGN AND METHODS: Platelet concentrates were produced from buffy coats by a standard large-scale production process. Buffy coats were separated from the red cell and plasma components, and then platelets were recovered from the buffy coats by a soft-spin procedure. Levels of cytokines (IL-1 beta, IL-6, IL-8, and TNF) were determined with commercial enzyme-linked immunosorbent assays. RESULTS: In platelet concentrates produced by the buffy coat method, IL-1 beta, IL-6, IL-8, and TNF were observed at or below the detection limit of current enzyme-linked immunosorbent assays after 5 days' storage at 22 +/- 2 degrees C. Therefore, prestorage filtration had no measurable effect on cytokine levels. In controls, IL-1 beta, IL-6, IL-8, and TNF were quantitatively detected after exogenous addition of recombinant cytokines or exposure to lipopolysaccharide. CONCLUSION: Platelet concentrates prepared from buffy coats may be virtually free of cytokines (IL-1 beta, IL-6, IL-8, and TNF) during 5 days of storage. Filtration is not required to reduce the recipient's cytokine exposure via such platelet concentrates.

Blood Platelets↗