Ultrastructure and peroxidase cytochemistry of normal human leukocytes at birth

At birth, differential and white blood cell counts of normal newborn infants are strikingly different from those of adults in that the number of leukocytes is increased and immature cells course through the circulation. In this study, our intent was to examine normal neonatal cord blood by electron microscopy and peroxidase cytochemistry to determine whether any detectable differences exist in the leukocytes of neonatal and adult blood. This investigation was undertaken because newborn infants have an increased susceptibility to infection, and alterations in phagocyte function have been implicated as the cause. Cord blood was found to contain mature leukocytes of all kinds, similar in ultrastructure and peroxidase localization to those of adults. Moreover, as indicated earlier by light microscopy, immature forms (normally found only in adult bone marrow) were present in the blood of newborns. We found that nearly all cell lines were represented in the neonatal circulation by such developmental forms as promyelocytes, myelocytes, promonocytes, erythroblasts, megakaryocytes, rare unidentifiable blasts, and dividing cells—all resembling their counterparts in adult bone marrow. With the techniques used here, neonatal leukocytes were similar to those of the adult in ultrastructure and peroxidase localization, although some had been mobilized into the blood in a remarkably immature state. This study, the first of its kind, will serve as a helpful background for future investigations of acquired, genetic or neoplastic leukocyte abnormalities which may be discovered at birth.     

Dissociable Influences of Skewness and Valence on Economic Choice and Neural Activity

Asymmetry in distributions of potential outcomes (i.e. skewness), and whether those potential outcomes reflect gains or losses (i.e. their valence), both exert a powerful influence on value-based choice. How valence affects the impact of skewness on choice is unknown. Here by orthogonally manipulating the skewness and valence of economic stimuli we show that both have an influence on choice. We show that the influence of skewness on choice is independent of valence, both across and within subjects. fMRI data revealed skew-related activity in bilateral anterior insula and dorsomedial prefrontal cortex, which shows no interaction with valence. Further, the expression of skew-related activity depends on an individual’s preference for skewness, and this was again independent of valence-related preference. Our findings highlight the importance of skewness in choice and show that its influence, both behaviourally and neurally, is distinct from an influence of valence.     

Stereospecific effects of ascorbic acid and analogues on D1 and D2 agonist binding.

Ascorbic acid inhibited the specific binding of both the D1 agonist, [3H] SKF 38393, and the D2 agonist, [3H] N-0437 at physiologically relevant concentrations. This inhibition was both stereospecific and receptor selective. Using ligand concentrations approximating their KD's, the IC50's for ascorbate and two structural analogues, isoascorbate and D-glucoascorbate, were determined. The rank order of IC50's at both D1 and D2 were D-glucoascorbate greater than isoascorbate greater than ascorbate. However, the IC50 for each compound was greater at D1 than D2. Evaluation of the relationship between the IC50 for ascorbate and the ligand concentration using both the D1 and the D2 ligand yielded data inconsistent with competitive inhibition models. Preliminary experiments were conducted to evaluate the site and type of inhibition with results consistent with an allostearic effect at the level of the receptor.     

Arabidopsis ADC1 functions as an N~δ-acetylornithine decarboxylase

Polyamines are small aliphatic amines found in almost all organisms, ranging from bacteria to plants and animals. In most plants, putrescine, the metabolic precursor for longer polyamines, such as spermidine and spermine, is produced from arginine, with either agmatine or ornithine as intermediates. Here we show that Arabidopsis thaliana(Arabidopsis) arginine decarboxylase 1(ADC1), one of the two known arginine decarboxylases in Arabidopsis, not only synthesizes agmatine from arginine, but also converts N~δ-acetylornithine to N-acetylputrescine. Phylogenetic analyses indicate that duplication and neofunctionalization of ADC1 and NATA1, the enzymes that synthesize N~δ-acetylornithine in Arabidopsis, co-occur in a small number of related species in the Brassicaceae. Unlike ADC2, which is localized in the chloroplasts, ADC1 is in the endoplasmic reticulum together with NATA1, an indication that these two enzymes have access to the same substrate pool. Together, these results are consistent with a model whereby NATA1 and ADC1 together provide a pathway for the synthesis of N-acetylputrescine in Arabidopsis.