Comparative study of spermatogonial survival after x-ray exposure, high LET (HZE) irradiation or spaceflight

Spermatogonial cell loss has been observed in rats flown on Space Lab 3, Cosmos 1887, Cosmos 2044 and in mice following irradiation with X-ray or with high energy (HZE) particle beams. Spermatogonial loss is determined by cell counting in maturation stage 6 seminiferous [correction of seminferous] tubules. With the exception of Iron, laboratory irradiation experiments (with mice) revealed a similar pattern of spermatogonial loss proportional to the radiation dose at levels less than 0.1 Gy. Helium and Argon irradiation resulted in a 5% loss of spermatogonia after only 0.01 Gy exposure. However, significant spermatogonial loss (45%) occured at this radiation level with Iron particle beams. The loss of spermatogonia during each space flight was less than 10% when compared to control (non-flight) animals. This loss, although small, was significant. Although radiation may be a contributing factor in the loss of spermatogonia during space flight, exposure levels, as determined by dosimetry, were not significant to account for the total cell loss observed.

Ultrastructure of phagocytosed Paracoccidioides brasiliensis in nonactivated or activated macrophages

Transmission electron microscopy was used to study ultrastructures in Paracoccidioides brasiliensis yeast cells after ingestion by nonactivated or cytokine-activated murine peritoneal macrophages. Yeast cells ingested by nonactivated macrophages had typical bi- and trilayered cell walls, plasma membranes, mitochondria, nuclei, vacuoles, etc., which remained intact for 24 h of coculture. In contrast, yeast cells ingested by activated macrophages exhibited abnormal mitochondrial ultrastructures within 4 h of interaction. Subsequent events that occurred were the formation of several clear vacuoles per cell, disintegration of the cytoplasm, and development of empty cells with intact walls. These findings provide, for the first time, insights into stepwise damage to fungal cells by activated macrophages (of particular interest in this instance because of prior evidence that the damage is due to nonoxidative mechanisms) and give possible clues regarding fungicidal mechanisms.

Morphological and biochemical examination of Cosmos 1887 rat heart tissue: Part I--Ultrastructure

Morphological changes were observed in the left ventricle of rat heart tissue from animals flown on the Cosmos 1887 biosatellite for 12.5 days. These tissues were compared to the synchronous and vivarium control hearts. While many normal myofibrils were observed, others exhibited ultrastructural alterations, i.e., damaged and irregular-shaped mitochondria and generalized myofibrillar edema. Analysis of variance (ANOVA) of the volume density data revealed a statistically significant increase in glycogen and a significant decrease in mitochondria compared to the synchronous and vivarium controls. Point counting indicated an increase in lipid and myeloid bodies and a decrease in microtubules, but these changes were not statistically significant. In addition, the flight animals exhibited some patchy loss of protofibrils (actin and myosin filaments) and some abnormal supercontracted myofibrils that were not seen in the controls. This study was undertaken to gain insight into the mechanistic aspects of cardiac changes in both animals and human beings as a consequence of space travel (1). Cardiac hypotrophy and fluid shifts have been observed after actual or simulated weightlessness and raise concerns about the functioning of the heart and circulatory system during and after travel in space (2-4).

Effects of spaceflight on the spermatogonial population of rat seminiferous epithelium

Testes from rats flown on Cosmos 1887 were compared with vivarium control and synchronous control samples. The mean weights of flight testes, normalized for weight per 100 g, were 6.4% less when compared with the vivarium controls. Counts of spermatogonia from tissue sections (seminiferous tubules in maturation stage 6) from five animals in each group revealed 4% fewer spermatogonia in flight testes compared with synchronous controls and 11% fewer spermatogonia in flight samples compared with vivarium controls.

Effects of high energy particle (HZE) radiation on the distal lung

Major sources of concern for manned space travel are the effects of high energy particle (HZE) radiation on various biological systems, and the consequences of major solar activity. To date, considerable attention has been directed toward HZE-induced alterations both on non-dividing systems, such as the retina, cornea and brain, and on dividing systems, such as the gut and testis. This paper is focused on the morphologically detectable late-occurring alterations in the distal lung, and toward a comparison of the changes with those induced by x-irradiation. Briefly, the salient alterations involve an increase in the width of the septal walls and the capillary and alveolar basal laminae, and the irregularity of the luminal surface of the capillaries, as exemplified by the presence of filipodial projections and blebbing. All alterations were focal in their localization, and no cells of any type (e.g., epithelial, endothelial or stromal) appeared to undergo damage, an observation quite unlike the cellular changes induced by x-irradiation.

Cardiac muscle ultrastructure and cyclic AMP reactions to altered gravity conditions

Morphological and biochemical analyses of heart muscle of rats subjected to microgravity on Spacelab 3 (SL-3) flight and rats born and reared under increased gravity (1.7 G) conditions were compared with 1-G controls. Electronmicroscopic studies showed an increase in the number of lipid droplets and in areas of glycogen storage. Distribution changes of microtubules and cytoskeletal elements from both SL-3 and 1.7-G groups were observed. The high Km cyclic AMP phosphodiesterase activity was lower (P less than 0.05) in SL-3 heart muscle, and low Km activity was lower in 1.7-G males but was unaltered in females. Cyclic AMP-dependent protein kinase (cA-PK) activity was decreased in subcellular fractions of heart muscle of SL-3 animals. Recompartmentalization of cA-PK activity occurred in particulate tissue fraction of 1.7-G animals (70.3% of total for 1.7 G vs. 35.9% for controls). Phosphorylation of endogenous low-mobility proteins increased in SL-3 heart-soluble fractions. Photoaffinity labeling (18 h, 4 degrees C) decreased in type II cA-PK regulatory (R) subunits in both SL-3 and in 1.7-G male heart tissue particulate fractions. The 1.7-G female heart R subunit distribution did not differ from controls. These findings indicate that in heart muscle altered gravity conditions influenced physiological reactions similar to catecholamine-induced receptor-mediated hormonal responses.

Axoglial contacts in the area postrema of the cat: an ultrastructural study

Axoglial contacts were observed in an ultrastructural study of the area postrema of the cat. According to the disposition of the electron-dense projections attached to the adjoining membranes these contacts were classified as symmetrical or asymmetrical. The axon profiles contained aggregations of clear vesicles randomly distributed or grouped in cluster adjacent to the electron-dense projections. Dense core vesicles were occasionally seen. The neuroglial profiles were either astrocytic or ependymoglial in nature. The astrocytes showed a clear cytoplasm, polymorphous vesicles, mitochondria, glycogen granules, and bundles of filaments. The ependymal cells, in contrast, had a more electron-dense and granular appearance, tubular structures, irregular vesicular formations, profiles of smooth reticuloendoplasm, and filaments grouped in bundles or isolated in the cytoplasm. The possibility that these contacts might play a role in the chemical transfer from neurons to glial cells is discussed on the basis of existing biochemical data.

Long term effects of low doses of 56Fe ions on the brain and retina of the mouse: ultrastructural and behavioral studies

Eight month old male C57BL6 mice were exposed without anesthesia to whole-body irradiation in circular holders. The mice were tested for behavioral decrements after 0.5 and 50 rads of Fe particle irradiation at 6 and 12 months post irradiation to obtain long term results. A standard maze was used and the animals were timed for completion thereof. A string test also was administered to the mice, testing their ability to grasp and move along a string to safety. The results from animals exposed to 50 rads were significantly different from [correction of fron] control results to p = < .001 in both systems of testing. The hippocampus (believed to be the location of environmental interaction in the brain) and the retina were examined for ultrastructural changes. The ultrastructural changes were similar to those we found in our Cosmos 782, 936 and in our Argon experiments. The mouse data indicate that iron particles were able to induce long term changes in the central nervous system which lead to behavioral impairment.

Fine-structural changes in the midgut of old Drosophila melanogaster

Variations of the mitochondrial structure with increasing age are of particular interest because the production of ATP is necessary for most cellular activities. Therefore, a senescent decrease of mitochondrial activity could jeopardize cell survival and function. We combined a statistical with a morphological approach to investigate these changes in mitochondrial size and structure of Drosophila melanogaster. The midgut epithelium is of special interest because previous research shows striking aging changes. Investigations of the mitochondria of flies of three age groups (10, 39, and 65 days) reveal an increase in size as well as in its standard deviation. This is linked to the fact that mitochondrial enlargement occurs especially in the luminal region. Ultrastructural studies show that with increasing age the mitochondria become more osmiophilic, their cristae disarranged, cristae-free areas can also be found, and there is an accumulation of homogeneous, granular and lamellar dense bodies. In addition, an accumulation of virus-like particles, fiber-shaped structures, reticular structures, and dense bodies without a surrounding membrane was found.

Effects of simulated increased gravity on the rate of aging of rats: implications for the rate of living theory of aging

Ever since Pearl proposed the rate of living theory of aging numerous studies have demonstrated its validity in poikilotherms. In mammals, however, satisfactory experimental demonstration is still lacking because an externally imposed increase of basal metabolic rate of these animals (e.g. by placement in the cold) is usually accompanied by general homeostatic disturbance and stress. The present study was based on the finding that rats exposed to slightly increased gravity are able to adapt with little chronic stress but at a higher level of basal metabolic expenditure (increased 'rate of living'). The rate of aging of 17-mth-old rats that had been exposed to 3.14 times normal gravity in an animal centrifuge for 8 mth was larger than of controls as shown by apparently elevated lipofuscin content in heart and kidney, reduced numbers and increased size of mitochondria of heart tissue, and inferior liver mitochondria respiration (reduced 'efficiency': 20% larger ADP: 0 ratio, P less than 0.01; reduced 'speed': 8% lower respiratory control ratio, P less than 0.05). On the other hand, steady-state food intake per day per kg body weight, which is presumably proportional to 'rate of living' or specific basal metabolic expenditure, was about 18% higher than in controls (P less than 0.01) after an initial 2-mth adaptation period. Finally, though half of the centrifuged animals lived only a little shorter than controls (average about 343 vs. 364 days on the centrifuge, difference statistically nonsignificant), the remaining half (longest survivors) lived on the centrifuge an average of 520 days (range 483-572) compared to an average of 574 days (range 502-615) for controls, computed from onset of centrifugation, or 11% shorter (P less than 0.01). Therefore, these results show that a moderate increase of the level of basal metabolism of young adult rats adapted to hypergravity compared to controls in normal gravity is accompanied by a roughly similar increase in the rate of organ aging and reduction of survival, in agreement with Pearl's rate of living theory of aging, previously experimentally demonstrated only in poikilotherms.

Spontaneous mutant of Blastomyces dermatitidis attenuated in virulence for mice

A spontaneous mutation occurred in cultures of a virulent strain of Blastomyces dermatitidis during serial passage at 35-37 degrees C. The mutant strain was shown to be 10,000-fold less virulent for mice than the parent strain, and this was independent of the challenge dose, the age of the challenged host, and the route of challenge (although attenuation was greater for pulmonary than for peritoneal challenge). The mutant grows as well as the parent in fungal media or in the presence of murine substrates. Studies of the chronology of pulmonary infection indicate the mutation affects an early event (first week after challenge) in establishment of infection and interaction with host defenses. Scanning electron microscopy showed that the mutant lacks deep irregular surface ridges and grooves present in the parent. It had increased resistance to crystal violet in vitro, increased susceptibility to bile, and could hydrolyze esculin. The latter findings are of interest because they place the mutant in an intermediate position with respect to these properties between the virulent parent and a previously studied avirulent strain. Lipid analyses indicated a marked increase in fatty acids in the mutant. Studies of four B. dermatitidis strains have also associated increasing palmitic acid and phospholipid content with increasing virulence.

Accelerated aging of fasted Drosophila. Preservation of physiological function and cellular fine structure by thiazolidine carboxylic acid (TCA)

Thiazolidine carboxylic acid (TCA) is a natural liver metabolite whose Mg-salt increased lifespan of flies and mice (Miquel and Economos, 1979, Exp. Geront. 14: 279). We studied the physiological and cellular fine structural effects of various concentrations of TCA in the food of male Drosophila. Flies on 0.3% TCA at 27 degrees C had a reduced oxygen consumption rate (about 20% less than controls) at 3 wks of age while their mating capacity and speed of mating were preserved; the flies lived in various experiments 20-30% longer than controls. Apparently TCA improved the metabolic efficiency of the flies (possibly from less "waste" of energy due to improved mitochondrial coupling). However, flies on 0.9% TCA had a reduced mating capacity and lifespan (:toxicity) while at 0.1% TCA was ineffective. A similar dose-response relationship was found in young flies treated with TCA for 1 week and then deprived of food and water, a procedure found to induce accelerated physiological aging. TCA at the 0.3% and 0.6% level reduced the speed of development and the size of the enclosed flies. Electron microscopic investigation of wing muscle showed that 0.3% TCA had a protective effect on cellular fine structure. Though in starved controls (40% survivors after 24 hours of starvation) there was a total absence of glycogen granules, and a striking shrinkage and densification of mitochondria, TCA to a large extent protected muscle cells from these effects of starvation.

Virulence of fungi: correlation of virulence of Blastomyces dermatitidis in vivo with escape from macrophage inhibition of replication in vitro

Strains of Blastomyces dermatitidis which are virulent (V), attenuated (A), or avirulent (AV) in mice have been identified. Virulence of V has been reported to be associated with its ability to replicate in vivo, causing lethal infections in the lungs or in the peritoneal cavity. We report here that V, but not A or AV, has the ability to replicate in vivo in nonlethal subcutaneous lesions. The possibility that V was able to replicate in vivo by evading primary host defenses was investigated. We studied the interaction of macrophages and strains of B. dermatitidis in vitro. In 24-h cocultures, the replication of all three strains of B. dermatitidis was inhibited by macrophages from: (i) untreated mice (20 to 40%), (ii) mice that had recovered from nonlethal blastomycosis (40 to 60%), (iii) concanavalin A-treated mice (50 to 70%), or (iv) peritoneal exudates elicited by thioglycolate (65 to 80%). However, at 72 h in the first three types of cocultures A and AV remained inhibited, whereas V was not inhibited (0 to 4%). Only the most inhibitory macrophages, those induced by thioglycollate, inhibited V at 72 h, though V was again less inhibited than A or AV at that time. Thus, we show a correlation between virulence of V in vivo and its ability to escape from macrophage inhibition of replication in vitro.

Retinal changes in rats flown on Cosmos 936: A cosmic ray experiment

Ten rats, five centrifuged during flight to simulate gravity and five stationary in flight and experiencing hypogravity, orbited the Earth. No differences were noted between flight-stationary and flight-centrifuged animals, but changes were seen between these two groups and ground controls. Morphological alterations were observed comparable to those in the experiment flown on Cosmos 782 and to the retinal cells exposed to high-energy particles at Berkeley. Affected cells in the outer nuclear layer showed swelling, clearing of cytoplasm, and disruption of the membranes. Tissue channels were again found, similar to those seen on 782. After space flight, preliminary data indicated an increase in cell size in montages of the nuclear layer of both groups of flight animals. This experiment shows that weightlessness and environmental conditions other than cosmic radiation do not contribute to the observed damage of retinal cells.

Effects of high-LET neon (20Ne) particle radiation on the brain, eyes and other head structures of the pocket mouse: a histological study

A study was made of tissues from 130 pocket mice after a single head-only exposure to high-LET 20Ne particle radiation at 1000, 100 or 10 rad (nominal surface dose) with the view of obtaining base"line data regarding the effectiveness of HZE (cosmic-ray) particles during spaceflight. First seen at 2-3 weeks after exposure, necrotic neurons in the cerebrum reached peak incidence (0 . 04 per cent at 1000 rad, 0 . 003 per cent at 100 rad and less than 0 . 0005 per cent at 10 rad) after 4-5 weeks and decreased to low levels thereafter. Incidence in the cerebellum was lower. Neuroglia, cells of the subependymal matrix and dentate gyrus precursor cells suffered acute damage at 1000 and at 100 rad. At 1000 rad, enlarged hyperchromatic neuroglia, first noted at 3 weeks, increased in number up to 7 months, then declined. Alterations in the retina and olfactory epithelium were seen at 1000 rad, and reaction in the scalp at 100 rad. Damage was incurred by dentinoblasts at 10 rad. Changes similar to those observed in pocket mice were found in the brains of gerbils and C57B1 mice.

Modification of a Kowa RC-2 fundus camera for self-photography without the use of mydriatics

Research on retinal circulation during space flight required the development of a simple technique to provide self monitoring of blood vessel changes in the fundus without the use of mydriatics. A Kowa RC-2 fundus camera was modified for self-photography by the use of a bite plate for positioning and cross hairs for focusing the subject's retina relative to the film plane. Dilation of the pupils without the use of mydriatics was accomplished by dark adaption of the subject. Pictures were obtained without pupil constriction by the use of a high speed strobe light. This method also has applications for clinical medicine.

Cosmic ray effects on the eyes of rats flown on Cosmos No. 782, experimental K-007

The eyes from six rats were fixed at the recovery site in Russia after they had circled the earth for 19.5 d in a 62.8 degree orbit. The eyes of six more flight rats were fixed 25 d later. These two preparations and eyes exposed to 1000 rad of neon and argon were compared to obtain data on possible radiation effects on the retina. Most of the flight eye tissue was normal; however, necrotic nuclei were found in the outer nuclear layer and channels were located in the outer segment area. Macrophages were seen between the pigment layer and outer segments. Comparison of the Day zero znd 25-d postflight eyes suggested some possible recovery. Light flashes seen by space travelers and damage from cosmic rays appear to arise from two different sites of interaction. The flashes are created by cosmic ray transversal of the outer segments while pathologic change, when it occurs, is quite possibly from interaction with some part of the nucleus. Nevertheless, direct interaction with other cellular components could also occur. Other factors, such as secondaries from spacecraft shielding, may play an important role.

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: XI. Results of eye examination

Five pocket mice (Perognathus longimembris) were flown on Apollo XVII, and four survived. All the eyes, except one eye from the dead flight mouse, were examined histologically. In the four surviving mice, a total of five cosmic ray particles which had registered in the subscalp particle detectors had trajectories that intersected the eyes. Four of them (Z equal to 6-9 for three of the particles and Z larger than or equal to 10 for the fourth) most likely went through the head before reaching the particle detector, while the thindown direction of the fifth (Z larger than or equal to 10) was not determinable. The retinas of the flight animals were found free from histological alterations such as might have been expected from encounters with cosmic ray particles.

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: VI. launch, flight, and recovery

The final phase to fly five pocket mice in the Apollo XVII command module was carried out at the NASA Kennedy Space Center. Upon completion of the 13-d space flight, the package was removed from the spacecraft and, after having been purged with an oxygen-helium gas mixture, was flown to American Samo. Four of the five mice were recovered alive from the package. Analysis of the mouse that died during the flight revealed several factors that could have contributed to its death, the chief of which was massive hemorrhage in its middle ear cavities.

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: V. preflight studies on tolerancee to oxygen and heat. Part III. effects on eyes

A study was made of the eyes of eight pocket mice exposed to oxygen at partial pressures of 8, 10, or 12 psi over a period of 7 d. At the termination of the exposure, the animals were decompressed to sea-level O2 either immediately or over a period of 30, 60, or 90 min. No pathological changes were found in any of the eyes, except in the retina of one of the animals exposed to 12 psi O2. Here, only a single rod photoreceptor was found damaged, an observation not regarded as significant. Hence, an oxygen partial pressure as high as 12 psi in the camister in which pocket mice were expected to fly on Apollo XVII would probably have no deleterious effect on the eyes of the animals.

The effects of cosmic particle radiation on pocket mice aboard Apollo XVII: VII. Cosmic ray particle dosimetry and trajectory tracing

Five pocket mice (Perognathus longimembris) were flown on Apollo XVII, each with a solid-state (plastic) nuclear track detector implanted beneath its scalp. The subscalp detectors were sensitive to HZE cosmic ray particles with a LET larger than or equal to 0.15 million electron volts per micrometer (MeV/mjm). A critical aspect of the dosimetry of the experiment involved tracing individual particle trajectories through each mouse head from particle tracks registered in the individual subscalp detectors, thereby establishing a one-to-one correspondence between a trajectory location in the tissue and the presence or absence of a lesion. The other major aspect was the identification of each registered particle. An average of 16 particles with Z larger than or equal to 6 and 2.2 particles with Z larger than or equal to 20 were found per detector. The track density, 29 tracks/cm2, when adjusted for detection volume, was in agreement with the photographic emulsion data from an area dosimeter located next to the flight package.

An electron microscopic investigation of age-dependent changes in the flight muscle of Musca domestica L

The thoracic flight muscle from adult male NAIDM house flies was examined, from emergence to very old age. Thin sections stained with uranyl acetate and bismuth showed no myofibrillar or mitochondrial degeneration from 1 day to 19 days post-emergence, contrary to earlier reports. Some progressive loss in glycogen content and increase in mitochondrial size were observed for muscle from young to very old flies. However, there was no conclusive evidence of fusion of smaller mitochondria into larger ones with advancing age, despite exhaustive examination of representative sections of muscle samples of adult males of different ages.

Ultrastructure of Pseudomonas saccharophila at early and late log phase of growth

The fine structure of Pseudomonas saccharophila, a soil bacterium, is similar to that of the marine Pseudomonas reported by Wiebe and Chapman. The unit membrane of the plasma membrane is clearly seen in some areas of thin sections. The ribonucleoprotein granules are distributed in the cytoplasm of the cell. Cells of P. saccharophila during early exponential phase are large, and most of them contain a large number of poly-beta-hydroxybutyrate granules. Some of the granules are quite large and occupy up to three-fourths of the cross section of the cell. Thin sections of the cells in the late log phase, however, show fewer and smaller poly-beta-hydroxybutyrate granules located in the central region of the cell. Negative-stained and freeze-fracture preparations show that the outer surface of the cell wall of P. saccharophila is covered with a large number of tiny granules and long, slender flagella. The outer surface of the plasma membrane appears to be smoother than the outer surface of the cell wall, and it also contains numerous granules. Since the outer surface of the cell wall is quite smooth in freeze-fracture preparations, the wrinkled appearance in thin sections is probably an artifact of fixation and dehydration. The poly-beta-hydroxybutyrate did not solidify at the freezing temperature used (approximately -150 C), and it was consequently pulled out in a spikelike structure during the fracturing process. P. saccharophila, under the conditions in our study, appears to multiply by the constrictive type of cell division.