Abortive Infection of Shigella dysenteriae P2 by T2 Bacteriophage

We have investigated some of the biochemical events that accompany the abortive infection by T2 of Shigella dysenteriae lysogenized with the temperate phage P2. After infection with T2, protein and RNA synthesis continued for 3 to 5 min. The virus-induced enzyme, deoxycytidylate hydroxymethylase was produced in reduced amounts (15% of normal), and the extent of deoxyribonucleic acid (DNA) synthesis was 0.1% of that found with a nonlysogenic strain. Measurements of the production of acid-soluble fragments and sedimentation analyses failed to detect enzymatic degradation of the infecting viral DNA which could be specifically related to the presence of the prophage P2. Each interaction between T2 and a bacterium resulted in the death of the cell. This observation is consistent with results obtained with other types of bacteria which show that only when a nucleolytic attack occurs on T2 DNA does the cell have an increased capacity to survive after adsorption of T2.     

Monoaminergic Effects of Folinic Acid, l-DOPA, and 5-Hydroxytryptophan in Dihydropteridine Reductase Deficiency

Abstract: Plasma and CSF concentrations of endogenous l -DOPA, catecholamines, and metabolites of monoamines were assayed in a patient with atypical phenylketonuria due to absent dihydropteridine reductase (DHPR), before and during treatment with folinic acid, Sinemet, and 5-hydroxytryptophan. The patient had low but detectable levels of l -DOPA, 3,4-dihydroxyphenylacetic acid (DOPAC), and 3,4-dihydroxyphenylglycol (DHPG) in plasma and low but detectable levels of these compounds and of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in CSF, with approximately normal plasma and CSF levels of norepinephrine [noradrenaline (NA)]. Folinic acid treatment approximately doubled plasma levels of l -DOPA, NA, DOPAC, and DHPG, compared with values during dietary phenylalanine restriction alone. Detection of l -DOPA, catecholamines, and monoamine metabolites in this patient indicates that monoamine synthesis in humans does not absolutely require DHPR. The results are consistent with the existence of an alternative biochemical pathway, with folinic acid treatment augmenting activity along this pathway. Low plasma levels of l -DOPA, DOPAC, and DHPG may reflect decreased catecholamine synthesis and turnover in sympathetic nerves, with compensatory increases in exocytotic release normalizing plasma NA levels.     

IL-4 can correct defective IgE production in SJA/9 mice.

SJA/9 mice are unable to produce significant serum IgE responses to either primary or secondary challenge with protein Ag or helminth parasites. Previous work has shown that this defect resides the T cell rather than with the B cells. These experiments test several possible explanations for the lack of IgE production in these mice. SJA/9 mice do not appear to overproduce IFN-gamma or any other antagonist of IL-4 function. Helminth parasite infection induces normal levels of IL-5-dependent eosinophilia, suggesting that there is not a complete absence of a Th2 response in these mice. The defect, however can be explained by a substantial reduction in IL-4 production in vivo and can be corrected by infusion with IL-4. The reason for this lack of IL-4 production is not yet clear and, paradoxically, SJA/9 T cells can be stimulated in vitro to produce IL-4 levels comparable to T cells from other strains.     

Comparison of estrogens and estrogen metabolites in human breast tissue and urine

Background  

An important aspect of the link between estrogen and breast cancer is whether urinary estrogen levels are representative of the intra-tissue levels of bioavailable estrogens.     

Lactate-mediated changes in growth morphology and transformation frequency of irradiated C3H 10T1/2 cells

Treatment of mammalian cells with lactate or inhibitors of glycolysis alters their radiation response, particularly in the low dose region of the dose response curve. The occurrence of both high lactate levels and high glycolytic metabolism in tumours is well known and therefore the effect of lactate on a cell line sensitive to radiation induced transformation was examined using a single exposure to Cobalt 60 gamma rays as the carcinogen challenge. The results indicate that cells treated with 5mM lactate before irradiation exhibit changes in morphology and growth rate and that the transformation frequency is increased by three to ten fold following 24 hours lactate treatment just prior to irradiation. Examination of radiation survival curves showed a positive correlation between transformation frequency and size of the shoulder, but increasing transformation frequency was associated with a decrease in Do. A mechanism involving altered Redox potential in lactate treated cells is suggested. The results are discussed in terms of their possible significance for radiotherapy.