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Yos9 is an essential component of the endoplasmic reticulum associated protein degradation (ERAD) system that is responsible for removing terminally misfolded proteins from the ER lumen and mediating proteasomal degradation in the cytosol. Glycoproteins that fail to attain their native conformation in the ER expose a distinct oligosaccharide structure, a terminal α1,6-linked mannose residue, that is specifically recognized by the mannose 6-phoshate receptor homology (MRH) domain of Yos9. We have determined the structure of the MRH domain of Yos9 in its free form and complexed with 3α, 6α-mannopentaose. We show that binding is achieved by loops between β-strands performing an inward movement and that this movement also affects the entire β-barrel leading to a twist. These rearrangements may facilitate the processing of client proteins by downstream acting factors. In contrast, other oligosaccharides such as 2α-mannobiose bind weakly with only locally occurring chemical shift changes underscoring the specificity of this substrate selection process within ERAD.

We report about the child of a mother with phenylketonuria, which is not suffering from PKU, but is microcephalic and mentally retarded. This retardation is probably a sequel of an intrauterine Hyper-Phenylalanine-status. It is supposed that an intrauterine damage of the offspring even in cases with low Phenylalanine-levels of the mother is possible.

In 148 children, 4 months to 14 1/2 years old, 192 serum-xylose-tests (XT) and small bowel biopsies have been performed because of suspected intestinal malabsorption. The results of the XT and of the biopsies were compared to investigate the diagnostic value of the XT with respect to the morphology of the small bowel mucosa. Further we wanted to determine at which time after the oral intake of xylose the best correlation of XT and morphology can be expected. In children with normal mucosa the XT differed significantly from those with subtotal mucosal atrophy but not with partial villous atrophy. However, partial villous atrophy could be differentiated from subtotal villous atrophy with the same test. In children with subtotal villous atrophy a statistically significant age-dependency could be observed, comparing children being less or more than 2 years old and also a dependency from periods with gluten-free diet. Partial villous atrophy with or without coeliac disease cannot be differentiated by means of the XT. Best correlation of the XT and the morphology of the small bowel mucosa can be found 60 minutes after the oral xylose load; no additional information is obtained by more blood-xylose-determinations (e.g. 30, 90, 120, 180 minutes). Because of the rather high standard deviation of the individual blood xylose values no exact prediction can be made from the XT to the mucosal morphology. Therefore the XT is only of value for screening purposes and its results should not influence the indication for a small bowel biopsy, derived from clinical considerations.

An influence on the production of Angiotensin-I by different ions is demonstrated. Plasma Renin activity was thereby measured by the methods of Boyd et al. (pH 7.5) and of Fyhrquist et al. (pH 6.0) at a concentration of each ion of 50 mmol/L. Ions of different size were used, ranging from Lithium to the Ammonium-ion. A definitive dependency of this effect on the Angiotensin production by the ion size could be shown. With Sodium the concentration in serum was varied at 5 levels (130-170 mmol/L) and Renin measured at Potassium concentrations in low (3.4-3.7 mmol/L) or high (4.8-5.1 mmol/L) so-called normal ranges. A marked increase of the production of Angiotensin-I with increasing sodium concentrations at a low Potassium range was observed and the opposite was true at high Potassium concentrations. These effects have to be taken into account when assaying Plasma Renin activity. In addition, they offer also an explanation of the well-known but unsolved facts of the influence of Sodium and Potassium on the pathogenesis of hypertonia.

We report about experiments to isolate Synaptosome-Membranes of the rat cerebellum in order to produce Antibodies directed toward these membranes in rabbits. The raised Antisera were tested in different Complement-fixation-assays. They reacted only with the Synaptosome-Membranes, not with heart, kidney, liver- and spleen-membranes. Different fractions of the isolation-procedure for synatosomal membranes were also checked for their ability to fix Complement. Only Synaptosomes and the synaptosomal membranes gave sufficient Complement fixation, while Mitochondria, soluble brain proteins, synaptic vesicles and braincell nuclei did not. These biochemical and immunological findings are further supported by electrophysiological data, where the transsynaptic component of the parallel fibre-evoked field potential was strongly suppressed by the administration of the immune sera containing antibodies against membranes of synaptosome fractions.

Amino acid screening in an institute for children with hearing defects led to the detection of a 14 years male with histidinuria. Further investigations established the diagnosis histidinemia. In this normal intelligent patient audiologic tests showed bilateral internal ear hearing defect. It is accepted that the hearing defect is the reason for speech abnormities in form of diminished articulation. But it is not clear how far the inborn error of histidine metabolism is directly responsible for the hearing loss. This observation suggests that the well known speech defects in histidinemics are partly caused by hearing disability.

A new method to measure restlessness is described. It consists mainly of recording thoracic electrical impedance and measuring the amount of movement artifacts appearing in the pneumographs. Technical equipment and data evaluation are described; an example of typical data is given together with proposals as to how the method may be automated. Potential applications in different fields of interest are described.

The case of a 12-year-old boy with cystine lysinuria is reported. Unusual in this case was the combination of severe mental retardation, cerebral attacks and temporary Parkinson-like neurological symptoms. Biochemically, a disturbance of the histidine reabsorption of the renal tubes was also apparent. Further examination that the renal amino acid reabsorption could not be influenced by treatment with tryptophan. The possible biochemical relationships are discussed.

The effect of insulin and glucagon on the anomeric composition of D-glucose in blood of children in the timecourse of tolerance tests has been investigated. Employing an improved enzymatic micromethod, specific for the anomers of D-glucose, insulin could be shown to raise the percentage of the alpha-anomer of the total serum glucose, whereas glucagon has no direct effect on the anomeric composition. However, an insulin-like effect could be observed in the second part of the glucagon tolerance test, e.g. alpha-D-glucose increased relatively to total glucose in serum and erythrocytes.

To elucidate the reaction mechanism of the increased elimination rate of bilirubin in the blood of newborns under the influence of Eucalyptol, we performed a study on young mice. The following results were obtained: UDPGA-T activity is increased 33%, if measured with 4-MU as substrate after a single injection (i.p.) of Eucalyptol (0.3 mg/g body weight), with bilirubin as substrate the increase is 112%. UDPG-T activity increases 29%. The enhancement of enzyme activities can be inhibited by Actinomycin D (1 MUg/g body weight) 30% (bilirubin), 48% (4-MU) respectively in the case of UDPGA-T. Under cycloheximide (2 mug/g body weight) the increase of the activity of UDPGA-T is suppressed by 59% (bilirubin) or 99% (4-MU) as compared to the corresponding controls. No significant difference in the activity of UDPG-T by actinomycin or cycloheximide can be observed between the controls and the Eucalyptol-treated group. We conclude that the increase of enzyme activity of UDPGA-T is mainly due to enzyme induction, while in the case of UDPG-T activation of enzyme molecules might be the underlying mechanism. The effect of Eucalyptol on the bilirubin level in the blood of newborns is comparable to the effect of phenobarbital.