Research Containing: Male

Long-term (6-wk) hindlimb suspension inhibits spermatogenesis in adult male rats

by cfynanon 9 June 2015in Biology & Biotechnology No comment

The International Space Station will allow extended habitation in space and long-term exposure to microgravity (microG). A concern is the impact of long-term microG exposure on the ability of species to reproduce. The model often used to simulate microG is rat hindlimb suspension (HLS), where the hindlimbs are elevated above the cage floor with a tail harness. Experiments described here are the first to examine the effect of long-term HLS on testicular function in adult male rats. Free-roaming (controls), animals with only the tail harnessed but hindlimbs in contact with the cage floor (TO), and HLS animals were tested for 6 wk. Cryptorchidism was prevented in TO and HLS animals by partial constriction of the inguinal canal with sutures. All parameters were compared at the end of the 6-wk experiment. Testicular weights and spermatogenesis were significantly reduced by HLS, such that no spermatogenic cells beyond round spermatids were present and epididymides were devoid of mature sperm. In many tubules, loss of all germ cells, except a few spermatogonia, resulting in histopathology similar to the Sertoli cell, was observed. Spermatogenesis appeared unaffected in control and TO animals. Sertoli and Leydig cell appearance, testosterone, luteinizing hormone, and follicle-stimulating hormone levels, and epididymal and seminal vesicle weight were unchanged by HLS. Cortisone was not elevated by HLS; thus stress may not be a factor. These results demonstrate that spermatogenesis is severely inhibited by long-term HLS, whereas testicular androgen production is not. These results have significant implications regarding serious effects of long-term exposure to microG on the reproductive capability of scrotal mammals, including humans.

Fertilization of sea urchin eggs and sperm motility are negatively impacted under low hypergravitational forces significant to space flight

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Sperm and other flagellates swim faster in microgravity (microG) than in 1 G, raising the question of whether fertilization is altered under conditions of space travel. Such alterations have implications for reproduction of plant and animal food and for long-term space habitation by man. We previously demonstrated that microG accelerates protein phosphorylation during initiation of sperm motility but delays the sperm response to the egg chemotactic factor, speract. Thus sperm are sensitive to changes in gravitational force. New experiments using the NiZeMi centrifugal microscope examined whether low hypergravity (hyperG) causes effects opposite to microG on sperm motility, signal transduction, and fertilization. Sperm % motility and straight-line velocity were significantly inhibited by as little as 1.3 G. The phosphorylation states of FP130, an axonemal phosphoprotein, and FP160, a cAMP-dependent salt-extractable flagellar protein, both coupled to motility activation, showed a more rapid decline in hyperG. Most critically, hyperG caused an approximately 50% reduction in both the rate of sperm-egg binding and fertilization. The similar extent of inhibition of both fertilization parameters in hyperG suggests that the primary effect is on sperm rather than eggs. These results not only support our earlier microG data demonstrating that sperm are sensitive to small changes in gravitational forces but more importantly now show that this sensitivity affects the ability of sperm to fertilize eggs. Thus, more detailed studies on the impact of space flight on development should include studies of sperm function and fertilization.

Bone turnover in wild type and pleiotrophin-transgenic mice housed for three months in the International Space Station (ISS)

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Bone is a complex dynamic tissue undergoing a continuous remodeling process. Gravity is a physical force playing a role in the remodeling and contributing to the maintenance of bone integrity. This article reports an investigation on the alterations of the bone microarchitecture that occurred in wild type (Wt) and pleiotrophin-transgenic (PTN-Tg) mice exposed to a near-zero gravity on the International Space Station (ISS) during the Mice Drawer System (MDS) mission, to date, the longest mice permanence (91 days) in space. The transgenic mouse strain over-expressing pleiotrophin (PTN) in bone was selected because of the PTN positive effects on bone turnover. Wt and PTN-Tg control animals were maintained on Earth either in a MDS payload or in a standard vivarium cage. This study revealed a bone loss during spaceflight in the weight-bearing bones of both strains. For both Tg and Wt a decrease of the trabecular number as well as an increase of the mean trabecular separation was observed after flight, whereas trabecular thickness did not show any significant change. Non weight-bearing bones were not affected. The PTN-Tg mice exposed to normal gravity presented a poorer trabecular organization than Wt mice, but interestingly, the expression of the PTN transgene during the flight resulted in some protection against microgravity's negative effects. Moreover, osteocytes of the Wt mice, but not of Tg mice, acquired a round shape, thus showing for the first time osteocyte space-related morphological alterations in vivo. The analysis of specific bone formation and resorption marker expression suggested that the microgravity-induced bone loss was due to both an increased bone resorption and a decreased bone deposition. Apparently, the PTN transgene protection was the result of a higher osteoblast activity in the flight mice.

Spaceflight-induced alterations in cerebral artery vasoconstrictor, mechanical, and structural properties: implications for elevated cerebral perfusion and intracranial pressure

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Evidence indicates that cerebral blood flow is both increased and diminished in astronauts on return to Earth. Data from ground-based animal models simulating the effects of microgravity have shown that decrements in cerebral perfusion are associated with enhanced vasoconstriction and structural remodeling of cerebral arteries. Based on these results, the purpose of this study was to test the hypothesis that 13 d of spaceflight [Space Transportation System (STS)-135 shuttle mission] enhances myogenic vasoconstriction, increases medial wall thickness, and elicits no change in the mechanical properties of mouse cerebral arteries. Basilar and posterior communicating arteries (PCAs) were isolated from 9-wk-old female C57BL/6 mice for in vitro vascular and mechanical testing. Contrary to that hypothesized, myogenic vasoconstrictor responses were lower and vascular distensibility greater in arteries from spaceflight group (SF) mice (n=7) relative to ground-based control group (GC) mice (n=12). Basilar artery maximal diameter was greater in SF mice (SF: 236+/-9 mum and GC: 215+/-5 mum) with no difference in medial wall thickness (SF: 12.4+/-1.6 mum; GC: 12.2+/-1.2 mum). Stiffness of the PCA, as characterized via nanoindentation, was lower in SF mice (SF: 3.4+/-0.3 N/m; GC: 5.4+/-0.8 N/m). Collectively, spaceflight-induced reductions in myogenic vasoconstriction and stiffness and increases in maximal diameter of cerebral arteries signify that elevations in brain blood flow may occur during spaceflight. Such changes in cerebral vascular control of perfusion could contribute to increases in intracranial pressure and an associated impairment of visual acuity in astronauts during spaceflight.

Microgravity effects on sea urchin fertilization and development

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Gravity has been a pervasive influence on all living systems and there is convincing evidence to suggest that it alters fertilization and embryogenesis in several developmental systems. Notwithstanding the global importance of gravity on development, it has only been recently possible to begin to design experiments which might directly investigate the specific effects of this vector. The goal of this research program is to explore and understand the effects of gravity on fertilization and early development using sea urchins as a model system. Sea urchin development has several advantages for this project including the feasibility of maintaining and manipulating these cells during spaceflight, the high percentage of normal fertilization and early development, and the abundant knowledge about molecular, biochemical, and cellular events during embryogenesis which permits detailed insights into the mechanism by which gravity might interfere with development. Furthermore, skeletal calcium is deposited into the embryonic spicules within a day of fertilization permitting studies of the effects of gravity on bone calcium deposition.

Latent and lytic Epstein-Barr virus gene expression in the peripheral blood of astronauts

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Epstein-Barr virus (EBV) latent and replicative gene transcription was analyzed in peripheral blood B-lymphocytes from astronauts who flew on short-duration ( approximately 11 days) Shuttle missions and long-duration ( approximately 180 days) International Space Station (ISS) missions. Latent, immediate-early, and early gene replicative viral transcripts were detected in samples from six astronauts who flew on short-duration Shuttle missions, whereas viral gene transcription was mostly absent in samples from 24 healthy donors. Samples from six astronauts who flew on long-duration ISS missions were characterized by expanded expression of latent, immediate-early, and early gene transcripts and new onset expression of late replicative transcription upon return to Earth. These data indicate that EBV-infected cells are no longer expressing the restricted set of viral genes that characterize latency but are expressing latent and lytic gene transcripts. These data also suggest the possibility of EBV-related complications in future long-duration missions, in particular interplanetary travel.

Adrenocortical and immune responses following short- and long-duration spaceflight

by cfynanon 9 June 2015in Biology & Biotechnology No comment

INTRODUCTION: Short-term spaceflight is associated with significant but reversible immunological alterations. However, little information exists on the effects of long-duration spaceflight on neuroimmune responses. METHODS: We collected multiple pre- and postflight samples from Shuttle and International Space Station (ISS) crewmembers in order to compare adrenocortical and immune responses between short- (approximately 11 d) and long-duration (approximately 180 d) spaceflight. RESULTS: In Shuttle crewmembers, increased stress hormone levels and altered leukocyte subsets were observed prior to launch and at landing. Additionally, typical stress-induced shifts in leukocyte and lymphocyte subsets, as well as the percentage of T-cells capable of producing intracellular IFN-gamma were also decreased just before launch and immediately after landing. Plasma IL-10 levels were increased before launch but not postflight. No preflight changes occurred in ISS crewmembers, but long-duration crewmembers exhibited significantly greater spikes in both plasma and urinary cortisol at landing as compared to Shuttle crewmembers. The percentage of T-cells capable of producing intracellular IFN-gamma was decreased in ISS crewmembers. Plasma IL-10 was increased postflight. Unexpectedly, stress-induced shifts in lymphocyte subpopulations were absent after long-duration flights despite significantly increased stress hormones at landing. CONCLUSION: Our results demonstrate significant differences in neuroimmune responses between astronauts flying on short-duration Shuttle missions versus long-duration ISS missions, and they agree with prior studies demonstrating the importance of mission duration in the magnitude of these changes.

Merging machines with microsurgery: clinical experience with neuroArm

by cfynanon 9 June 2015in Biology & Biotechnology No comment

OBJECT: It has been over a decade since the introduction of the da Vinci Surgical System into surgery. Since then, technology has been advancing at an exponential rate, and newer surgical robots are becoming increasingly sophisticated, which could greatly impact the performance of surgery. NeuroArm is one such robotic system. METHODS: Clinical integration of neuroArm, an MR-compatible image-guided robot, into surgical procedure has been developed over a prospective series of 35 cases with varying pathology. RESULTS: Only 1 adverse event was encountered in the first 35 neuroArm cases, with no patient injury. The adverse event was uncontrolled motion of the left neuroArm manipulator, which was corrected through a rigorous safety review procedure. Surgeons used a graded approach to introducing neuroArm into surgery, with routine dissection of the tumor-brain interface occurring over the last 15 cases. The use of neuroArm for routine dissection shows that robotic technology can be successfully integrated into microsurgery. Karnofsky performance status scores were significantly improved postoperatively and at 12-week follow-up. CONCLUSIONS: Surgical robots have the potential to improve surgical precision and accuracy through motion scaling and tremor filters, although human surgeons currently possess superior speed and dexterity. Additionally, neuroArm's workstation has positive implications for technology management and surgical education. NeuroArm is a step toward a future in which a variety of machines are merged with medicine.

Recovery of spaceflight-induced bone loss: Bone mineral density after long-duration missions as fitted with an exponential function

by cfynanon 9 June 2015in Biology & Biotechnology No comment

The loss of bone mineral in NASA astronauts during spaceflight has been investigated throughout the more than 40 years of space travel. Consequently, it is a medical requirement at NASA Johnson Space Center (JSC) that changes in bone mass be monitored in crew members by measuring bone mineral density (BMD), with dual-energy X-ray absorptiometry (DXA) before and after flight, of astronauts who serve on long-duration missions (4?6 months). We evaluated this repository of medical data to track whether there is recovery of bone mineral that was lost during spaceflight.Our analysis was supplemented by BMD data from cosmonauts (by convention, a space traveler formally employed by the Russia Aviation and Space Agency or by the previous Soviet Union) who had also flown on long-duration missions. Data from a total of 45 individual crew members a small number of whom flew on more than one mission were used in this analysis. Changes in BMD (between 56 different sets of pre- and postflight measurements) were plotted as a function of time (days after landing). Plotted BMD changes were fitted to an exponential mathematical function that estimated: (i) BMD change on landing day (day 0) and (ii) the number of days after landing when 50% of the lost bone would be recovered (50% recovery time) in the lumbar spine, trochanter, pelvis, femoral neck and calcaneus. In sum, averaged losses of bone mineral after long-duration spaceflight ranged between 2% and 9% across all sites with our recovery model predicting a 50% restoration of bone loss for all sites to be within 9 months.

Space shuttle flight crew spatial orientation survey results

by cfynanon 9 June 2015in Biology & Biotechnology No comment

BACKGROUND & METHOD: A survey was distributed to 77 Space Shuttle flight crew members; 40 responded covering 71 missions. The goal was to capture historical information before Shuttle retirement and to better understand subjective experiences of illusory sensations due to the transition from 1-G to microgravity and back. RESULTS: We analyzed the response data to answer four questions: 1) Do older astronauts suffer more from illusory sensations than younger astronauts? We conclude that they do not because younger flight crew had about twice the rate of illusory sensations as older flight crew. 2) Do trial head motions during re-entry in an effort to hasten readaptation to 1-G really help? Apparently not because those who made trial head motions had a 38% rate of illusory sensations whereas those who did not make trial head motions had a 15% rate of illusory sensations. 3) Do symptoms decrease as flight experience increases? Yes, as reported in other publications, although there are individual exceptions. 4) Do longer duration missions lead to more illusory sensations and readaptation difficulties than shorter duration missions? Yes, the rate of illusory sensations for longer missions was 38%, whereas it was 24% for shorter missions. DISCUSSION: Based upon our results, long-duration missions may induce orientation problems that could have significant mission impacts.

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Research Containing: Male

Long-term (6-wk) hindlimb suspension inhibits spermatogenesis in adult male rats

Fertilization of sea urchin eggs and sperm motility are negatively impacted under low hypergravitational forces significant to space flight

Bone turnover in wild type and pleiotrophin-transgenic mice housed for three months in the International Space Station (ISS)

Spaceflight-induced alterations in cerebral artery vasoconstrictor, mechanical, and structural properties: implications for elevated cerebral perfusion and intracranial pressure

Microgravity effects on sea urchin fertilization and development

Latent and lytic Epstein-Barr virus gene expression in the peripheral blood of astronauts

Adrenocortical and immune responses following short- and long-duration spaceflight

Merging machines with microsurgery: clinical experience with neuroArm

Recovery of spaceflight-induced bone loss: Bone mineral density after long-duration missions as fitted with an exponential function

Space shuttle flight crew spatial orientation survey results