Kurt I. Altman

THE EFFECT OF IONIZING RADIATION ON DEOXYRIBONUCLEASE ACTIVITIES OF BODY FLUIDS. I. THE EFFECT OF TOTAL BODY EXPOSURE ON THE URINARY EXCRETION OF DEOXYRIBONUCLEASES

Abstract 1. 1. Some of the properties of urinary DNases of the rat have been described. 2. 2. It has been shown that there is increased acid and neutral DNase activity in the urine of rats exposed to total body x-rays.

The Effect of Ionizing Radiations on Connective Tissue

Publisher Summary Connective tissue pervades the entire organism, ensuring its matricial interconnections and its structural stability. Typically, connective tissue consists of extracellular material produced by cells that synthesize and secrete these materials. The physiological functions of connective tissues are determined by the nature and organization of their extracellular components. This chapter discusses all extracellular structural material such as fibrils and fibers, ground substance, bone, cartilage, and the cells elaborating this material such as fibroblasts, chondrocytes, osteocytes, and osteoblasts. Radiation-induced changes in connective tissue involve, among other things, excessive deposition of collagen in tissues. This, in turn, leads in many instances to interstitial, arteriolocapillary, or septal fibrosis. Exposure to ionizing radiations may also affect other components of connective tissue such as elastin and the glycosaminoglycans. The chapter reviews the biochemistry of connective tissue. It has now been established that the immunologic attributes of collagen are closely linked to its chemical structure.

The effect of ionizing radiation on deoxyribonuclease activities of body fluids. II. The plasma DNases after total body irradiation

Abstract 1. 1. The activity of DNase I (pH optimum 7.5) and DNase II (pH optimum 5.6) is markedly elevated in the plasma of irradiated rats. 2. 2. The maximum activity of DNase I occurs 6 days after exposure whereas the peak activity of DNase II occurs 1 day after exposure.

Dose Dependency of Radiation-Induced Creatine Excretion in Rat Urine

Creatine excretion in urine of rats after whole-body exposure to various doses of x rays (25 to 1000 r) and after sham-irradiation was determined. Although creatinuria was observed at all levels of exposure, the degree was dependent on the dose. Creatinuria lasted from 3 to 16 days after exposure. In the intermediate dose range a second rise in the excretion of creatine was observed during the second week after exposure. The average creatine excretion during the initial 4 days after exposure varied linearly with the dose up to 650 r.

A note on the synthesis of fatty acids in bone marrow homogenates as affected by X-radiation☆

1. 1. The synthesis of saturated and unsaturated fatty acids in bone marrow homogenates from untreated and X-radiated rabbits has been studied with α-14C-acetate as a precursor. 2. 2. Two and three-fold increases, respectively, over preradiation levels in saturated and unsaturated fatty acid synthesis were observed immediately after radiation. 3. 3. Whereas saturated fatty acid synthesis, which approached control values at 48 hours after radiation, again increased 312 times 72 hours after radiation, unsaturated fatty acid synthesis had fallen to 18% of the preradiation value. At 158 hours after radiation, the relationship between saturated and unsaturated fatty acid synthesis was reversed since unsaturated fatty acid synthesis had risen to 283% and saturated fatty acid synthesis had dropped to 58% of the preradiation value. 4. 4. Oxygen uptake and 14CO2 production increased immediately after radiation, reaching preradiation values 48 hours after exposure. 14CO2 evolution decreased steadily throughout the experimental period while oxygen uptake was unchanged 158 hours after exposure. 5. 5. Hemin synthesis after radiation has been found to behave in a manner similar to that observed in other studies. 6. 6. The term W has been introduced to denote the capacity of the bone marrow to synthesize fatty acids from α-14C-acetate.

Studies on the Metabolism of Tissue Proteins: III. The Turnover of Soluble Proteins and Elastin Labelled with 14C proline and its Relation to Exposure to Total-body X-irradiation

SummaryRats were injected with proline-U-14C and exposed to total-body x-irradiation at various time-intervals thereafter. Proline was isolated from the soluble protein and elastin fractions of various organs and its specific activity determined. In most organs an increase in specific activity of proline of these two protein fractions was observed after irradiation. This was interpreted to mean either a lowered metabolic replacement or a loss of certain components from these protein fractions after irradiation. It is suggested that the decrease in specific activity observed in the spleen is correlated to changes in the cell-population in this organ after irradiation.

Studies of collagen turnover in lathyritic rats

Abstract Normal and lathyritic rats were injected with proline-U-C 14 and sacrificed at different time intervals after the injection. The neutral salt soluble and insoluble fractions of collagen were prepared from skin and bone, as well as total collagen from bone. Proline and hydroxyproline were isolated from all collagen fractions, and the respective specific activity was determined. On the basis of the data on incorporation and replacement of radioactivity in collagen and its fractions, it appears that the conversion of soluble to insoluble collagen is impaired in lathyrism.

Radiation-induced tissue breakdown. IV. The source of degraded amino acids in irradiated rats.

Summary1. An attempt was made to determine the source of excess 14C -labelled glycine and phenylalanine observed in ‘free’ metabolic pools of rats loaded with glycine-2-14C and phenylalanine-3-14C before irradiation.2. Tissues from various organs of irradiated and non-irradiated rats were fractionated into three protein fractions. Glycine, phenylalanine, tyrosine, serine and alanine were isolated from these fractions, and the respective specific activities were determined.3. Differences in specific activities were : decreased activity in muscle collagen and soluble-protein fractions of thymus and spleen; increased activity in soluble-protein fractions of liver and muscle; and variable changes in the activity of certain amino acids of the soluble-protein fraction of kidney.4. The significance of these changes is discussed in terms of known biological effects of radiation on cells and cellular metabolism.5. Muscle collagen seems radio-sensitive and its increased catabolism in irradiated rats could explain m...

Urinary Excretion of Several Metabolites in Persons Accidentally Exposed to Ionizing Radiation

BS>Urinary concentrations of creatine, beta -aminoisobutyric acid, pyrrole --carboxylic acid, and free hydroxyproline were determined in human subjects accidentally exposed to ionizing radiation at various time intervals after exposure. The range of doses of radiation varied from about 100 to 4000 rads. Increased concentrations of creatine and beta -aminoisobutyric acid in urine were found in most of the patients. Excretion of free hydroxyproline was decreased in the three most heavily exposed patients, whereas pyrrolecarboxylic acid was increased only in the fatally injured patient. (auth)

Metabolism of Benzoic Acid in Normal and Irradiated Rats.

Summary 1. The isotope concentration of the urinary hippuric acid of starved irradiated or non-irradiated rats given benzoic acid-carboxyl-C14 is much less than the dilution expected from the conjugation of the injected labeled benzoic acid with inert carbon atoms of the glycyl residue. 2. Evidence is presented that benzoic acid is a normally occurring metabolite in rats. 3. The effect of xradiation on the ability of starved rats to conjugate benzoic acid-carboxyl-C14 has been tested and no defect detected under the experimental conditions used.