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Biomedical subjects

B Maak

Publications and source records attributed to B Maak.

33 records · Page 2Linked to original sources
PubMed1978

Factor VIII activity and factor VIII related antigen in newborns.

Factor VIII procoagulant activity and factor VIII related antigen were examined in 20 full-term and preterm newborn infants during the first days of life. The control group involved 15 adults volunteers. Factor VIII activity was estimated by a one-stage test and factor VIII related antigen was determined by immunelectrophoresis according to Laurell, using our own rabbit antiserum. The following results were obtained:--Factor VIII activity during the first 3 days of life did not differ from the normal range of the adult controls.--The concentration of factor VIII related antigen in newborns was markedly higher than in adults on the first, and to a lesser extent on the second, day of life.--The antigen concentration decreases on the second and following days of life to adult levels. The cause of this discrepancy cannot be completely explained but possible reasons are discussed.

Age Factors↗
PubMed1977

Antibody neutralizing material of factor VII during the first weeks of life.

In a study on 66 newborns and infants, factor VII activity and factor VII related antigen were investigated on 110 occasions. A normal range was calculated by testing plasma from 12 healthy male volunteers at various dilutions. Most of the values in the newborns and infants fell within this range but 18.2% of the factor VII proteins showed a significantly different specific activity.

Antigens↗
PubMed1977

The influence of perinatal risk factors on the incidence of atypical coagulation factor VII during the first days of life.

The correlation between the appearance of functionally-atypical factor VII and perinatal complications was investigated in 66 newborn infants. The presence of an abnormal clotting factor was assumed if the ratio between clotting activity and antigen-related factor VII material exceeded the normal range for adult plasma. The newborns were divided into a risk group of infants threatened by adverse conditions of labour or post-natal adaptation, and a control group of newborns without perinatal complications. The findings were as follows: The incidence of atypical factor VII was significantly higher in the risk group. There was no difference between prenatal and postnatal complications in this respect. Infants born by caesarian section or with cord complications, as well as those with delayed respiratory adaptation, showed a higher incidence of atypical factor VII than the risk group as a whole. Atypical factor VII was not detected until the third day of life, irrespective of the prenatal or postnatal complications. These findings suggest that perinatal risk factors are associated with an alteration of factor VII synthesis.

Age Factors↗
PubMed1975

[Methodological studies on the immunologic determination of proconvertin (factor VII)].

The influence of the different determinations of factor VII activities on the determination of the concentrations of the immunoreactive factor VII in the neutralizing test according to Good-Night were re-examined. The measurement of activity was performed with Seitz filtered cattle plasma as a complex proof of factor VII and X and with a specific artificial deficiency plasma. The examinations had the following results: In the plasma of healthy grown-up people there is a considerable, apparently physiologic range of dispersion of the immunoreactive concentration of factor VII within its normal activity which can be traced irrespective of the used measurements of activity. In plasma samples with a decreased activity of factor VII the values of measurement of the complex evidence will surpass those of the specific determination. The extent of neutralizing the activity in factor VII is not only dependent on the antibody concentration, but will mostly depend on the antibody-antigen relation. The findings obtained prove that the natural deficiency plasma of factor VII used in the original method of Goodnight can be replaced by an artificial substrate plasma.

Adult↗