Effects of irradiation on macrophagic response and transport of particles across the alveolar epithelium

Macrophagic production and particulate penetration into the lung were studied in mice depleted of monocytes by whole body irradiation. Subsequent intratracheal instillation of 4 mg carbon resulted in a much smaller adaptive increase in the number of alveolar macrophages, as compared with nonirradiated animals. The decreased macrophagic output was associated with increased passage of free carbon across the Type 1 alveolar epithelium in increased accumulation of carbon in interstitial macrophages and hilar lymph nodes of irradiated mice. The results suggest that interference with the adaptive outpouring of alveolar macrophages following a particulate load facilitates the interaction of particles with macrophages within the pulmonary interstitium, where fibrogenic factors released in response to toxic agents would have a maximum effect.

Autophagy in frog visual cells in vitro

Isolated frog retinas were incubated in a medium free of serum and amino acids under dim white incandescent light of 20 lux/m2. After 1, 2, 6, and 9 hr of incubation, six retinas at each time point were fixed for electron microscopic investigation. Histochemical staining of acid phosphatase was performed in control and experimental tissues. Autophagic vacuoles in visual cell inner segments were counted and compared with the incidence of vacuoles in control tissues. The ratio of newly formed: old autophagic vacuoles was assessed in incubated retinas, and the number of autophagic vacuoles per rod cell and per cone cell was evaluated. The results indicated that the number of autophagic vacuoles was significantly increased from 1 to 9 hr of incubation, the ratio of newly formed: old autophagic vacuoles was constant over this period, and the amount of autophagy occurring in rods and cones was similar. In a second group of experiments, retinas were incubated under the same conditions but at two different levels of illumination. One series of retinas was incubated in dim red incandescent light of 5 lux/m2, the other series was incubated at bright white fluorescent light of 300 lux/m2. The total numbers of autophagic vacuoles showed a consistent elevation of 20% in bright white light material as compared wot dim red light material. Autophagic vacuoles per cone were significantly higher in retinas incubated in white light than in retinas incubated in red light. Autophagic vacuoles per rod were about equal in both groups. Our observations indicated that visual cells contain an intracellular mechanism of degradation, which is increased under changed metabolic conditions and modified as a function of different levels of illumination.

Absorptive function of peripheral blood neutrophils in irradiated animals

It was shown in experiments on rats, dogs, and monkeys, irradiated with x rays or the gamma rays of 60 Co, that a decrease in the indices of phagocytosis is observed only 3-4 weeks after irradiation. It is concluded that the absorptive function of mature neutrophils in radioresistant, and the cells whose maturation occurred after the influence of ionizing radiation are inadequate.

Effect of gamma ray low doses on the system of the nonspecific defense of the organism

The author studied the response of the mechanical stage of the RES phagocytosis and the serum lysozyme level in white mice after fractionated exposures to 10 R and 100 R daily. It was observed the activation of these systems after low summed doses and, on the other hand, its significant depression after high summed doses. The causes of these changes are discussed.

Functional, biochemical, and morphologic changes in alveolar macrophages following thoracic x-irradiation

Alveolar macrophages lavaged from mice at various times after 1800 rads of thoracic x-irradiation were compared to control mice. Determination of their numbers, size distribution, glass adherence, latex particle uptake, cytochemistry, morphology, protein, phospholipid, and hydrolytic enzyme composition showed that defective bacterial uptake and clearance, which has been demonstrated by other workers, may be related to a transient decrease in their numbers rather than activity. A decrease in numbers is explainable on the basis of a population of radiosensitive precursors in the lung interstitium. The work load in the alveolar space may prolong the duration of their residence in the alveoli as well as increase their size and content of hydrolytic enzymes and ingested surfactant components.

A new, albino-beige mouse: giant granules in retinal pigment epithelium

Albino-beige mice were produced in order to combine two experimentally useful characteristics, albinism and lysosomal dysfunction, in the same animal. The retinal pigment epithelium of albino-beige mice formed giant intracellular granules. Exposure of albino-beige mice to white light of 150 foot-candles for 3 to 10 hr induced marked phagocytosis of rod outer segment fragments by the retinal pigment epithelium, resulting in intracellular accumulations of undigested disk membranes within the giant granules. Additional, incompletely processed membranes accumulated as the mice aged or were exposed to 150 foot-candle light for longer periods. Such accumulations of ingested membranes were not observed in the pigment epithelium of exposed or aging albino mice heterozygous for the beige gene. Because of its altered processing of ingested outer segment membranes, this new albino mouse should be useful for studying the possible roles of the retinal pigment epithelium in the maintenance of photoreceptor cells and in their recovery from light damage and other insults.

[Biological effects in the partial irradiation of dogs with high-energy protons]

Biological effects of irradiation of the head, chest and stomach of dogs with 250 Mev protons at a dose of 600 rad were investigated. Due to irradiation all the animals developed radiation sickness of moderate severity. A comparative study of the peripheral blood and immunobiological reactivity of the dogs showed that an exposure of the head exerted the least effect; an exposure of the chest and stomach had a very similar effect.

[Effects of 6-methyl-uracil upon the phagocytic activity in mice following whole-body X-irradiation OR 2,4,6-triethyleneimino-s-triazine treatment (author's transl)]

1. Phagocytic activity measured by means of the intravasal clearance of a soot dispersion in male NMRI-mice was increased six to ten days after whole-body X-irradiation (640 R) and decreased during the same period after i.v. administration of 2,4,6-triethyleneimino-s-triazine (TEM 2.0 mg/kg). 2. By means of 6-methyl-uracil food admixtures (200 to 400 ppm during 2 or 3 weeks) or by repeated intravenous injections of a N-methyl-D-glucosamine-6-methyluracil complex (62.5 to 250 mg/kg daily during five days), a significant augmentation of the phagocytic index being related to time and dosage was obtained in otherwise untreated mice. Comparable results were seen using cytidine and cytidine-s'-phosphate, whereas guanosine-5'-phosphate remained ineffective. 3. Whilst stimulating effects of 6-methyl-uracil or its N-methyl-D-glucosamine complex on X-irradiated mice were suspended, an increase up to supernormal values of the phagocytic index was produced by the pyrimidine base in animals treated with TEM. In accordance to this the survival rate of lethally X-irradiated mice (960 R) could not be increased; with animals given lethal TEM-doses, however, a significantly increased survival rate was obtained. 4. The present investigations as well as former biochemical analyses confirm the assumption that 6-methyluracil produces its regeneration effects, to some extent at least, by specific pathways influencing the reticuloendothelium. Different results from X-irradiated and TEM-treated mice are referring to the different points of attack of the two noxa.

In vitro reactivity of macrophages and lymphocytes from ultraviolet-irradiated mice

In these experiments we examined the ability of lymphocytes and macrophages from UV-treated mice of the inbred strain C3H/HeN(MTV-) to respond in vitro to nonspecific stimuli. Spleen and lymph node cells from UV-treated mice exhibited blastogenic responses to concanavalin A, phytohemagglutinin, and lipopolysaccharide that were equal to those of lymphoid cells from normal animals. Neither the induction of peritoneal exudate cells by inflammatory agents nor the phagocytic activity of peritoneal macrophages was affected by UV irradiation. Furthermore, no reduction occurred in the in vitro tumoricidal capacity of peritoneal macrophages from UV-treated mice after in vitro activation with xenogeneic lymphokines or endotoxin. We concluded that chronic UV irradiation does not lead to a generalized suppression of the immune system in mice.

[Phagocytic activity by guinea-pig peritoneal macrophages and human peripheral leukocytes irradiated in vitro (author's transl)]

A dose/effect curve for phagocytic activity of guinea-pig peritoneal macrophages and human peripheral leukocytes was determined ranging from anti-inflammatory to immunosuppressive doses. The nitroblutetrazolium reduction test was used stimulating the phagocytes by latex microspheres. A significant enhancement of phagocytic activity by low doses of gamma radiation was observed in guinea-pig macrophages.