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C Vermeer

Publications and source records attributed to C Vermeer.

141 records · Page 8Linked to original sources
PubMed1976

Contributions to the optimal use of human blood. VIII. Stability of blood coagulation factor VII during collection and storage of whole blood and plasma.

Investigations were performed concerning the influence of the pH on the stability of factor VIII during the collection of blood and during the storage of blood and plasma for varying periods and at varying temperatures. It was found that the low pH of ACD anticoagulant solution (pH 4.9) caused a loss of factor VIII procoagulant activity of 10-15% during the collection of blood. However, when less acidic anticoagulant solutions were used, substantial losses of factor VIII occurred during the storage of blood. We concluded that the optimal pH of both the anticoagulant solution and the stored blood, should be between 6.7 and 7.0. However, no anticoagulant solution is known that meets these requirements. In practice ACD ensures the highest recovery of factor VIII in cryoprecipitate, at least in those cases where the blood donations are stored for several hours before separation and freezing of the plasma.

Anticoagulants↗
PubMed1976

Contribution to the optimal use of human blood. VII. Increase of the yield of factor VIII in four-donor cryoprecipitate by an improved processing of blood and plasma.

The influence of different variables on the yield of factor VIII in cryoprecipitate as prepared in the Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, was studied. The following conclusions may be drawn: (1) In case blood should be stored, the use of the anticoagulant solution acid citrate dextrose (ACD) is preferable to citrate phosphate dextrose (CPD) or trisodium citrate (TSC). (2) The temperature of stored whole blood should not decrease below 8 degrees C because of a spontaneous precipitation of factor VIII from blood (and plasma) below this temperature. (3) Cryoprecipitate derived from rapidly frozen plasma (1 min) contains a decreased amount of proteins in comparison with cryoprecipitate prepared from slowly frozen plasma (45 min to 4 h). On the other hand, equal amounts of factor VIII activity were obtained in the precipitate after freezing of plasma at varying rates. (4) Rapid thawing of plasma results in both higher yields of factor VIII procoagulant activity and a higher specific activity of this factor in the resulting cryoprecipitate. (5) The sedimentation of cryoprecipitate is completed after 5 min centrifugation at 1,500 g. (6) At temperatures higher than 8 degrees C, cryoprecipitated factor VIII starts dissolving into the supernatant plasma or in buffer. (7) Factor VIII in lyophilized cryoprecipitate is stable at room temperature. At elevated temperatures it rapidly looses its activity. (8) Evidence was obtained that the improvements which are introduced in the preparation of factor VIII do not lead to a product which is less stable in vitro as well as in vivo.

Anticoagulants↗
PubMedDate not supplied

Effect of oral anticoagulant treatment on markers for calcium and bone metabolism.

Vitamin K-dependent proteins regulate blood coagulation as well as bone growth and calcification. Here, we have compared the effects of oral anticoagulants on circulating vitamin K-dependent proteins and on markers for calcium and bone metabolism. Patients with a clinical indication for antithrombotic therapy were randomized into three groups and treated with either aspirin, regular-intensity anticoagulation [target international normalized ratio (INR) values: 2.5-3.5] or low-intensity anticoagulation (target INR values: 1.1-1.6). At the start and after 1 year of treatment, various biochemical markers were assessed. Both the circulating levels and the degree of carboxylation of the various gamma-carboxyglutamate (Gla)-containing proteins were affected differently by oral anticoagulant treatment. Circulating osteocalcin was more sensitive to poor vitamin K status than other Gla proteins. From the fact that - except for osteocalcin - neither markers for osteoblast nor osteoclast function were affected by oral anticoagulant treatment, we conclude that bone turnover remained unaltered, which is indicative of an unchanged rate of bone loss. Whether the long-term production of undercarboxylated bone Gla proteins may have a negative effect on the quality of bone (e.g. bone strength) cannot be concluded from this study.

Administration, Oral↗
PubMedDate not supplied

Determination of phylloquinone and menaquinones in food. Effect of food matrix on circulating vitamin K concentrations.

Fluctuations in international normalized ratio values are often ascribed to dietary changes in vitamin K intake. Here we present a database with vitamin K(1) and K(2) contents of a wide variety of food items. K(1) was mainly present in green vegetables and plant margarins, K(2) in meat, liver, butter, egg yolk, natto, cheese and curd cheese. To investigate the effect of the food matrix on vitamin K bioavailability, 6 healthy male volunteers consumed either a detergent-solubilized K(1) (3.5 micromol) or a meal consisting 400 g of spinach (3.5 micromol K(1)) and 200 g of natto (3.1 micromol K(2)). The absorption of pure K(1) was faster than that of food-bound K vitamins (serum peak values at 4 h vs. 6 h after ingestion). Moreover, circulating K(2) concentrations after the consumption of natto were about 10 times higher than those of K(1) after eating spinach. It is concluded that the contribution of K(2) vitamins (menaquinones) to the human vitamin K status is presently underestimated, and that their potential interference with oral anticoagulant treatment needs to be investigated.

Adult↗
PubMedDate not supplied

Characterization of a Gla-containing protein from calcified human atherosclerotic plaques.

In this article we describe the isolation of a 4-carboxyglutamic acid (Gla)-containing protein from calcified human atherosclerotic plaques. The protein was extracted from pulverized calcified plaques by demineralization with ethylenediaminetetraacetate and was subsequently purified by anion-exchange fast protein and high-performance liquid chromatography by using ion-exchange and gel-filtration columns. The protein was designated as plaque Gla protein (PGP) and has an apparent mass of 23 kD as estimated from sodium dodecyl sulfate-polyacrylamide gel analysis. By determining the sequence of its first six amino acid residues, the protein was unequivocally demonstrated to be not related to any other known protein. Moreover, no immunological relationship (as tested by Western blot analysis) was found between PGP and other known Gla-containing proteins.

1-Carboxyglutamic Acid↗