Knut Laake

The Mini‐Mental State Examination: Identifying the Most Efficient Variables for Detecting Cognitive Impairment in the Elderly

To study how well the scoring on each item of the MMSE relates to the sum‐score when the purpose is to identify persons with cognitive impairment, and to identify an equally effective subset of MMSE items for predicting cognitive impairment.

A low, 'normal' score on the Mini-Mental State Examination predicts development of dementia after three years

OBJECTIVES: To study whether a low, “normal” sumscore (i.e., 24 or higher) on the Mini‐Mental Status Examination (MMSE) near the cutpoint usually employed for identifying persons with cognitive impairment predicts later development of dementia.

Activation of purified plasma factor VII by human plasmin, plasma kallikrein, and activated components of the human intrinsic blood coagulation system

Purified plasma factor VII was incubated with purified plasmin, plasma kallikrein, factor IXa, factor XIa, factor XIIf, or activated factor XII in a calcium-free milieu. Plasmin, factor IXa, and glass—activated factor XII induced a considerable time- and temperature—dependent activation of factor VII. Plasma kallikrein gave weak activation of factor VII at 25°C and was inactive at 0°C. Kallikrein activated factor VII significantly through its effect as a plasminogen activator. The factor XIa was inactive towards factor VII. The effects of plasmin on factor VII were fully inhibited by SBTI (0.1 mg/ml); factor IXa and glass-activated factor XII were partially inhibited. The mechanism of the contact- and the cold-promoted activation of factor VII in human plasma is discussed.

Factor XII-induced fibrinolysis: studies on the separation of prekallikrein, plasminogen proactivator, and factor XI in human plasma.

Abstract A protein fraction containing plasma prekallikrein, factor XII-dependent plasminogen proactivator, and precursor factor XI was prepared by ion exchange chromatography of human plasma. The fraction was concentrated and subjected to further separation. No separation of plasma prekallikrein and plasminogen proactivator was obtained, either by chromatography on CM-Sephadex C-50, hydroxylapatite, or Sephadex G-100 Superfine, or by isoelectric focusing. Plasma prekallikrein separated clearly from precursor factor XI by chromatography on CM-Sephadex C-50, hydroxylapatite, and Sephadex G-100 Superfine. Isoelectric focusing revealed microheterogeneity of prekallikrein, and each peak had plasminogen preactivator activity. Studies with purified C1-inactivator indicated that the affinity of the inhibitor against plasma kallikrein and plasminogen activator is the same. A highly purified preparation of plasma prekallikrein (34.5 BAEe U/mg) also had plasminogen proactivator activity, and the plasminogen-activating capacity of the preparation calculated per BAEe proesterase U (0.16 Ploug unit/BAEe U) was unchanged during the purification procedure. It is concluded that plasma prekallikrein may be a mediator of the factor XII-dependent fibrinolytic pathway of human plasma.

Determination of factor XII in human plasma with arginine proesterase (prekallikrein) I. Preparation and properties of the substrate

Abstract An arginine proesterase was purified from human plasma by ion exchange chromatography and was concentrated on hydroxylapatite. Upon activation the preparation yielded 0.96 BAEe esterase units per mg protein. The preparation contained traces of factor XI, but was devoid of factor XII. One major arginine proesterase peak was observed after analytical gel filtration on Sephadex G-100 Superfine and disc electrophoresis at pH 4.3. The proesterase was activated by incubation with kaolin-treated plasma and was identified as plasma prekallikrein. Upon incubation with kaolin-treated plasma the activation proceeded at a constant rate to about 30% consumption of the proesterase. It is concluded that the preparation may serve as a substrate for determination of factor XII in plasma.

Inactivation and binding of human plasma kallikrein by antithrombin III and heparin

Abstract Purified human antithrombin III was found to inactivate the esterase, the kininogenase, and the plasminogen activator activity of purified plasma kallikrein. The reaction rate was increased by heparin. Kinetic studies indicated second-order kinetics for the reaction between kallikrein and antithrombin III, and a catalytic effect of heparin. SDS polyacrylamide gel electrophoresis revealed that three new bands were generated during the inactivation of kallikrein by antithrombin III. Heparin did not influence the factor XII-dependent activation of prekallikrein in human plasma, whereas the inactivation of kallikrein elapsed slightly more rapidly in plasma samples where heparin was added. It is concluded that antithrombin III probably is of minor importance for the inactivation of kallikrein in plasma under physiological circumstances.

Isolation and characterization of a prealbumin activator of prekallikrein from acetone-activated human plasma

Abstract A prealbumin activator of prekallikrein was isolated from acetone-activated human plasma by preparative disc gel electrophoresis in 15% polyacrylamide. The purification factor was 70, and the recovery was 20–30%. The purified preparation was functionally free of factors II, IX, and X, and it did not clot fibrinogen. It had a weak BAEe esterase activity, but was inactive towards kininogen, fibrin, and plasminogen. C1-inactivator, α 2 -macroglobulin, and α 1 -mantitrypsin could not be demonstrated by immunochemical techniques. The preparation was homogeneous on disc gel electrophoresis. The prekallikrein activator in the preparation had an estimated molecular weight of 32,000, and the isoelectric point was 4.2. The preparation also activated plasminogen proactivator and the proenzyme form of factor XI. It is concluded that the preparation contained factor XII f , and that preparative polyacrylamide disc gel electrophoresis of acetone-activated plasma may represent a simple method for the purification of factor XII f .

Purification and some characteristics of factor VII in human citrated plasma, glass-activated serum, and cold-activated plasma

Abstract Employing batchwise adsorption with DE 11 cellulose, aluminium hydroxide gel adsorption and desorption, preparative polyacrylamide disc gel electrophoresis, and DE 52 cellulose chromatography, factor VII was isolated from human plasma, glass-activated serum, and cold-activated plasma to specific activities corresponding to 30,000–100,000-fold purification. Soybean trypsin inhibitor was used to minimize formation of activated forms of factor VII during the purification. The activity of the purified plasma factor VII preparations was increased to 450–800% by incubation with kaolin and aluminium hydroxide-adsorbed plasma. The molecular weights of the factor VII preparations from the three sources were estimated at 58,000–62,000 daltons by gel filtration. The unactivated factor VII isolated from plasma was isoelectric at pH 4.50–4.70, and glass-activated serum factor VII was isoelectric in the region pH 5.35–5.55. Cold-activated plasma factor VII focused with one peak which coincided with traces of factor II at pH 4.60–4.70, and with one broad peak in the region pH 5.10–5.60.

Purification of human factor IX.

Abstract Factor IX was isolated from human plasma by a six-step procedure employing adsorption to DE-52 cellulose in batches, aluminium hydroxide adsorption, affinity chromatography on heparin-coupled Sepharose, preparative polyacrylamide disc gel electrophoresis, immunosorbent absorption, and DE-52 cellulose chromatography. Determination of factor IX activity and antigen revealed a specific activity of about 290 U per absorbancy unit at 280 nm. Analytical polyacrylamide disc gel electrophoresis showed one major and three to four minor bands with lower electrophoretic mobility. Disc gel electrophoresis in the presence of 10 M urea gave a double major band and two additional minor bands with higher electrophoretic mobility. One major band was observed in SDS polyacrylamide gel electrophoresis, and no change in mobility took place after reduction.

Factor IX in warfarin treated patients.

Abstract The presence of inactive factor IX molecules (acarboxy-IX) was demonstrated in plasma from warfarin treated patients by immunoelectrophoretic techniques using a precipitating rabbit antiserum against human factor IX. The level of factor IX activity (mean 0.42 units/ml) was lower than the level of factor IX antigen determined by an electroimmunoassay technique (mean 0.70 units/ml) in 34 of the 35 patients studied. The percentage Thrombotest values correlated positively with the level of factor IX activity (r=0.74) and negatively with the relative amount of acarboxy-IX (r=−0.54). Crossed immunoelectrophoresis in the presence of calcium ions of patient plasma revealed a factor IX antigen with a faster electrophoretic mobility than that of normal factor IX. Factor IX antigen from the patient with the largest amount of acarboxy-IX had a lower affinity to BaSO 4 than factor IX antigen from normal plasma. Neutralization of factor IX in the patient plasma samples by antiserum gave increased percentage Thrombotest values but had no effect on the Normotest values. The effect of the antiserum on the Thrombotest values was about the same on the patient plasma samples as on undiluted and diluted plasma from normal persons.