Enzymic determination of d-galactose, d-arabinose,and their homologs

The enzymes d-galactose dehydrogenase and d-arabinose dehydrogenase were demonstrated to be applicable to the quantitative determination of d-galactose (and homologs) and d-arabinose (and homologs), respectively. The enzymic reactions were quite specific. When coupled with β-galactosidase, d-galactose dehydrogenase could be used in the quantitative determination of β-galactosides.     

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.     

Morphogenetic studies of a genetically controlled tumor-like condition in Lycopersicon hybrids

Summary A dominant tumor-like condition recently isolated in a tomato hybrid is described from the viewpoint of morphogenesis. Tumors, consisting of masses of enlarged parenchymatous cells, generally appear on the ventral surface of the third leaf and the subsequently formed leaves of the hybrid derivatives. These outgrowths do not differentiate into teratomas. Abortive floral buds develop under greenhouse conditions and the tumorous plants are much dwarfed compared to the normal segregants of the same population. the same tumor genotype behaves differently under the field conditions: it grows and blossoms like the normal plants, setting fruits with viable seeds, and tumors fail to develop. Thus, tumor expression and general morphology of the tumor plants are greatly modified by environmental conditions.Tissue culture studies employing a variety of media have shown that tissues excised from tumor-producing plants are not autonomous with respect to growth hormones, nor are tissues from the non-tumorous segregants. Nevertheless, tissues from tumor and non-tumor genotypes show different growth requirements. Tumor and non-tumor tomatoes can thus be distinguished on the basis of in vitro growth responses, a result consistent with their different genetic constitution. Differentiation of buds or roots was not observed in either type of tissue.Abbreviations used GA gibberellic acid - IAA 3-indoleacetic acid - 2.4-D 2.4-dichlorophenoxyacetic acid Work Supported by National Science Foundation Grant GB-3198 and funds from The Cairncrest Foundation.     

The Hypothalamic-Pituitary-Adrenocortical System—Clinical Evaluation by Pharmacologic Techniques

The hypothalamic-pituitary-adrenocortical system is a complex negative feed-back control mechanism. Under non-stress conditions it functions to maintain a circadian rhythm of adrenal steroid production which is secondary to a circadian fluctuation in the sensitivity to suppression of acth by hydrocortisone. Any stressful stimulus causes an augmentation of steroid production which is due in part to a decrease in sensitivity of acth to suppression. Aldosterone production is not primarily controlled by acth.The increased understanding of this system and of its pathologic alterations has led to the development of a number of pharmacologic techniques which have proved most valuable in evaluating its integrity. Hypothalamic-pituitary function can be assessed by the response to the administration of dexamethasone, methopyrapone, bacterial pyrogen and vasopressin. Adrenal cortical function can be assessed by the response to acth, dexamethasone and spironolactone.     

THE FINE STRUCTURE OF STREPTOMYCES VIOLACEORUBER (S. COELICOLOR) : III. The Walls of the Mycelium and Spores

A study of thin sections of hyphae of Streptomyces violaceoruber in the electron microscope showed that the structure of the walls and the mode of formation of cross-walls are similar to those of Gram-positive bacteria. A beaded structure was seen in some regions of the wall, and the significance of this observation is discussed in relation to previous studies of the fine structure of bacterial cell walls. Elements of the intracytoplasmic membrane system appear to be involved in the process of cross-wall formation. The walls of the hyphae of the aerial mycelium divide into two layers before the spores are formed, and only the inner component of the wall grows inwards to form the cross-walls and so delimit the spores. The outer component remains intact for a time and acts as a sheath around the developing spores. Finally the sheath breaks and the spores are liberated. This process is contrasted with the formation of endospores in eubacteria. When the spores germinate, the walls of the germ tubes are continuous with those of the spores.