Phenylketonuria—Experience at One Center in the First Year of Screening in California

One year''s experience with phenylketonuria during the calendar year 1966, the first year for compulsory newborn screening in California, was reviewed. The over-all prevalence rate from reported cases in California during this period was one case per 19,500 persons tested. Fifty-seven persons suspected of having pku were evaluated, and 25 of them were determined to be phenylketonuric. Eleven of the 25 were infants in whom the abnormality was detected through the newborn screening program or because it was detected in a sibling through a screening program. All the newborn phenylketonuric patients were developing normally at the time of last report (although the follow-up periods were short).In nine of the other children, pku was detected because they were retarded. Five retarded children who were diagnosed as phenylketonuric at another clinic were given dietary assistance.Five additional infants had elevated serum phenylalanines but did not have the classic biochemical findings of pku and are being evaluated further. Nine infants with positive screening tests exhibited biochemical and clinical findings consistent with transient tyrosinemia. Eighteen other children were evaluated and found to have no metabolic abnormality.The newborn screening program for pku is of decided benefit in early identification of a group of infants who have a high rate of potentially serious metabolic disease. Early identification permits treatment soon enough to prevent mental retardation. Newly identified patients should be evaluated in a medical setting capable of careful pediatric, biochemical and nutritional surveillance.     

The effect of iron chelate fertilization of poplar upon CO2-uptake,leaf size,and content of leaf pigments and iron

Summary Potted poplars (strainsmarilandica, serotina andFlachslanden ofPopulus euramericana) which developed iron-deficiency symptoms (chlorosis of upper leaves, winter die-back of leader, flushing of lateral buds) were treated with a soil application of iron chelate to study the effect of iron nutrition upon CO₂-uptake, iron and pigment content of leaves, and leaf size of a tree species. Foliar content of each iron, chlorophyll, -carotene, lutein, and violaxanthin was significantly increased by the treatment. Chlorophyll b proved to be particularly sensitive to iron supply and the Q^a/b was also significantly altered.CO₂-uptake increased in fertilized and non-fertilized leaves with increasing light up to 40,000 Lux, but fertilized leaves assimilated more CO₂ than non-fertilized leaves, especially at light intensities from 5,000 Lux upwards. The assimilatory number was decreased by the iron application since larger amounts of chlorophyll were present in fertilized leaves. If CO₂-uptake was based upon an area unit basis the fertilizer effect became distinct even at 500 Lux. Thus CO₂-uptake is a quick, valuable measure of fertilizer responses.In severe cases, iron deficiency also affects leaf size and thus indirectly reduces photosynthetic activity. A chelate application during the growing season will not affect the size of leaves already formed but may considerably increase the size of leaves formed subsequent to the treatment.     

ESR-Untersuchungen an bestrahlten schwefelhaltigen und schwefelfreien Pyridoxinderivaten

Zusammenfassung Sowohl nach UV-Bestrahlung (254 nm) als auch nach Röntgenbestrahlung bei 20 °C ergeben sich für Pyridoxin und einige schwefelhaltige Pyridoxinderivate gleiche Radikalzustände. Wahrscheinlich befindet sich ein unpaares Elektron in der Methylgruppe der Stellung 4 oder 5. Bei den Derivaten, die den Schwefel in Form des Sulfhydryls enthalten, findet eine Radikalwanderung zum Schwefel statt. Dabei wird der Radikalzustand am Schwefel des 4-Mercaptopyridoxins schneller gebildet als im Falle des 5-Mercaptopyridoxins. Die Disulfidbindung des Pyrithioxins ist gegenüber den Sulfhydrylbindungen der Mercaptopyridoxine stabiler. Ist der Schwefel in Form eines Thioäthers vorhanden (4,5-Methylensulfidpvridoxin), so erhält man ein Radikal vom Alkyltyp, ohne daß anschließend eine Radikalwanderung zum Schwefel auftritt. Die ESR-Untersuchungen zeigen darüber hinaus, daß die Bildung und das Zeitverhalten der Radikale nicht nur von ihrer unmittelbaren Umgebung, sondern auch von der ganzen Struktur des Moleküls abhängig sind.Herrn Prof. Dr. KurtSommermeyer zum 60. Geburtstag gewidmet.     

MHC class II invariant chains in antigen processing and presentation

Most protein antigens cannot elicit a T-cell response unless they are processed to peptides, which are then presented to T lymphocytes by surface MHC class II molecules. Recent evidence supports an essential role of the invariant chain associated with class II MHC polypeptides in antigen processing.     

The Na+,K+,2Cl- -cotransport system in HeLa cells and HeLa cell mutants exhibiting an altered efflux pathway

We have investigated the characteristics of a transport system in HeLa cells, which turned out to be very similar to a previously described Na+, K+, 2Cl- -cotransport system. For further understanding about the physiological role of the cotransporter, we have mutagenized HeLa cells and selected progeny cells for growth in low potassium (0.2 mM) medium. The selected HeLa cells (LK1) exhibited alterations in the Na+,K+,2Cl- -cotransport system. LK1 cells showed a remarkable reduction of 86Rb+ efflux via the cotransporter when compared to the parental HeLa cells. In contrast, bumetanide-sensitive potassium influx, measured by 86Rb+ uptake, was increased in the LK1 cells (increase in Vmax). Km values of the cotransporter in HeLa cells and LK1 mutants revealed similar properties for 86Rb+ and 22Na+ uptake. In addition, (3H)-bumetanide binding studies were carried out on intact HeLa cells; 1.7 pmol/mg protein (3H)-bumetanide was specifically bound to HeLa parental cells, which could be calculated to a number of 103,000 binding sites/cell. LK1 cells present, 1.44 pmol/mg protein, specifically bound (3H)-bumetanide and, respectively, 137,000 binding sites/cell. The LK1 cells also exhibited an increase in the number of (3H)-ouabain binding sites as well as an increase in the activity of the Na+,K+-ATPase, expressed as a function of ouabain-sensitive 86Rb+ uptake. Furthermore, LK1 cells were different in the concentrations of intracellular Na+ (increases) and K+ (decreases) when compared to the HeLa parental cells. When grown in low K+ medium (0.2 mM K+), protein content and cell volume were increased in the LK1 cells, while the DNA content was not significantly different between both cell lines.