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Biomedical subjects

A Knapp

Publications and source records attributed to A Knapp.

At least 73 records · Page 4Linked to original sources
PubMed1976

On the population genetics of phenylketonuria in the G.D.R.

By means of the analysis of the geographical distribution of the birth-places of cases with phenylketonuria, who were detected in a nation-wide screening for phenylketonuria by the Guthrie test during a period of more than 5 years, 3 areas with a remarkably different frequency can be recognized: a) in the districts of Cottbus, Leipzig, Halle and Frankfort the frequency of the phenylketonuria is amounting to 1:6275, of the phenylketonuria-gene to 0.0126 and of the heterozygotes to 2.49%; b) in the remaining districts with the exception of two districts the frequency is significantly lower (1:11272, 0.0094, 1.86%); c) in the districts of Karl-Marx-Stadt and Neubrandenburg this metabolic disease is relatively rare (1:14769, 0.0082, 1.63%). In regions with a high frequency of the phenylketonuria the permanent mild hyperphenylalaninaemia is also twice more frequent than in the remaining country.

Gene Frequency↗
PubMed1975

[Phenylalanine hydroxylase activity in the liver as a parameter for distinguishing various forms of hyperphenylalaninemias (author's transl)].

The activity of phenylalanine hydroxylase in the liver without the cofactor 2-amino-4-hydroxy-6,7-dimethyl-5,6,7,8-tetrahydropterin is similar in cases of classical PKU (14 cases), mild hyperphenylalaninemias (2 cases), heterozygotes (1 case) and normal controls (18 cases). The addition of cofactor increases the activity 30-40-fold in normal controls and 2-5 fold in mild hyperphenylalaninemias or heterozygotes. In classical PKU the addition of cofactor is without effect or causes even a diminution of activity. Therefore, for classification of the various forms of hyperphenylalaninemias the effect of cofactor on enzyme activity is important. For decisions from this findings to be made as to whether treatment should or should not be used further investigations are needed.

Adolescent↗
PubMed1975

[Prenatal brain damage in maternal, untreated phenylketonuria].

Several reports in literature exist about mentally retarded non-phenylketonuric offspring from untreated phenylketonuric mothers with normal intelligence. One additional case is added who was detected after screening of about 1600 pregnant women. Biochemical investigations of the mother identified her as "classical phenylketonuria". Column chromatographic analysis of amino acids in amniotic fluid revealed a very high pheylalanine level and the diminution of the other, especially essential amino acids. The estimated amino acids in fetal brain also revealed a very high phenylalanine level. Routine screening for phenylketonuria by means of the Guthrie's test is recommended for all pregnant women at the first visit of the counseling.

Amino Acids↗
PubMed1975

[Tryptophan metabolism research in oligophrenic children. 4.: Activity and possibility of activating hepatic kynureninase after vitamin B6 treatment].

In 8 selected test persons of the 3rd series of experiments who were showing signs of pathological kynureninase activity, hepatic kynureninase was again established after 3 week's treatment with large doses of vitamin B6. The enormous in-vivo activation of the kynureninasis established goes to prove that apoenzyme synthesis may be stimulated by pyridoxine. On the basis of these results and the relative frequency of disorders dependent on B6, the question arises whether children from endangered families should not be given prophylactic vitamin B6 treatment from birth.

Adolescent↗
PubMed1975

[Determination of kynureninase activity in oligophrenic children with hereditary taint, before and after vitamin B6 treatment].

Kynureninase activity assay in oligophrenic children with hereditary taint, before and after treatment with vitamin B6. The hepatic kynureninase activity was assayed in 25 oligophrenic children with hereditary taint, and having a positive tryptophan load test. Eight cases (32%) showed an enzyme activity below the 2-s limit; in two cases, the pathologic enzyme activity could be almost normalized by addition of higher P-5-P concentrations. In a second set of studies, eight children with an abnormally low kynureninase activity were re-examined following a 3-week treatment with vitamin B6. The enormous in-vivo-activation of kynureninase reached in these studies lends support to the assumption of a vitamin-B6-dependent "inborn error of metabolism" in the tryptophan-kynurenin pathway in some of the investigated oligophrenic children with hereditary taint.

Adolescent↗