[Tryptophan metabolism and oligophrenia (author's transl)]. / Tryptophanstoffwechsel und Oligophrenie. Teil 1: Literaturübersicht.

After dealing with the biochemistry of tryptophan metabolism the most important results obtained in humans are presented. Special emphasis is given to the hereditary defects of tryptophan metabolism associated with mental retardation and convulsions due to lack of pyridoxine. The author's findings demonstrate the existence of a hereditary disturbance of the tryptophan metabolism via kynurenine in a certain part of oligophrenic patients. This metabolic defect can be controlled by high doses of vitamin B6. Furthermore investigations conducted with a view to interpreting these results are discussed, especially the determination of kynureninase activity, serotonin blood levels and pyridine nucleotide synthesis.

[Tryptophan metabolism research in oligophrenic children. 4.: Activity and possibility of activating hepatic kynureninase after vitamin B6 treatment]. / Tryptophanstoffwechseluntersuchungen bei oligophrenen Kindern. 4. Mitteilung: Aktivität und Aktivierbarkeit der hepatischen Kynureninase nach Vitamin B6-Behandlung

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.

[Determination of kynureninase activity in oligophrenic children with hereditary taint, before and after vitamin B6 treatment]. / Kynureninase-Aktivitätsbestimmungen bei oligophrenen Kindern mit familiärer Belastung vor und nach Vitamin B6-Behandlung

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.