The role of depressed metabolism in increased radio-resistance

The results of experiments on hamsters and rats to determine physiological responses to various temperature conditions are presented. The experimental methods described are considered to be applicable to future mammalian experiments in space. Renal function was examined in the golden hamster as a function of body temperature. Hamsters were also acclimated to heat and metabolic rates, body temperature, skin temperature, cardiac distribution and whole body hematocrits were measured. In addition, the effects of heat stress on the intestinal transport of sugars in the hamster and rat were studied. The biological effects of prolonged space flight and methods of simulating weightlessness are also discussed

Stress, temperature, heart rate, and hibernating factors in hamsters

Pathophysiological conditions resulting from prolonged exposure to zero gravity, cabin constraint, altered ambient environment, whether it be noise, vibrations, high temperatures, or combinations of such factors, are studied in laboratory animals and applied to manned space flight. Results and plans for further study are presented. Specific topics covered include: thermoregulation and its role in reflecting stress and adaptation to the gravity free environment and cabin confinement with its altered circadian forcings; renal function and its measurement in electrolyte distribution and blood flow dynamics; gastronintestinal function and an assessment of altered absorptive capacity in the intestinal mucosa; and catecholamine metabolism in terms of distribution and turnover rates in specific tissues

The role of depressed metabolism in increased radio resistance

Studies are presented of the physiology of depressed metabolism, radio-resistance in depressed metabolic states, comparative aspects of depressed metabolism, and gastrointestinal responses to ionizing radiation. Specific data cover helium-cold induced hypothermia in white rats and hamsters, and radiation responses and intestinal absorption in the gerbil

Experiment K-6-08. Biochemical and histochemical observations of vastus medialis

Muscles of the hindlimb in the rat have been used to demonstrate the effects of unloading in weightlessness and in animal models used to mimic weightlessness. The vastus medialis (VM) is discussed here. Samples were obtained from rats exposed to weightlessness for 12 days in Cosmos 1887 (Experiment K-6-08, coordinated by Dr. V.S. Oganov). The principal objective of this study was to ascertain if the vastus medialis responded to 12 days of microgravity exposure. The loss in muscle mass is greatest, -43 percent, when comparing F vs B, and least, -13 percent, when comparing F vs. V. Taken at face value these differences may be misleading. Due to the variability of the muscle weight in the basal group, these muscle mass losses may be exaggerated. In terms of percent water, there were no differences between the flight and the control groups. In spite of the limited sample, researchers conclude that muscle mass changes in the VM are not significant. Although some of the morphological parameters suggest a small degree of atrophy in the vastus medialis, the biochemical analyses (protein, RNA and DNA) suggest that these may be minimal and functionally nonsignificant. The relatively similar CS and LDH activities of VM from F and various control groups, as well as the lack of difference in LPL activity between F and S rats, suggests that there is little or no effect on the oxidative or glycolytic function of this muscle. Since the VM is chiefly a mixed fast twitch muscle, these metabolic indices of energy production are relatively unchanged. The results of VM studies are in agreement with previous observations of another type II fast twitch muscle, the EDL, from SL-3 rats which did not respond markedly to weightlessness and whole body suspension

Rat Cardiovascular Responses to Whole Body Suspension: Head-down and Non-Head-Down Tilt

The rat whole body suspension technique mimics responses seen during exposure to microgravity and was evaluated as a model for cardiovascular responses with two series of experiments. In one series, changes were monitored in chronically catheterized rats during 7 days of Head-Down Tilt (HDT) or Non-Head-Down Tilt (N-HDT) and after several hours of recovery. Elevations of mean arterial (MAP), systolic, and diastolic pressures of approx. 20 % (P less than 0.05) in HDT rats began as early as day 1 and were maintained for the duration of suspension. Pulse pressures were relatively unaffected, but heart rates were elevated approx. 10 %. During postsuspension (2-7 h), most cardiovascular parameters returned to presuspension levels. N-HDT rats exhibited elevations chiefly on days 3 and 7. In the second series, blood pressure was monitored in 1- and 3-day HDT and N-HDT rats to evaluate responses to rapid head-up tilt. MAP, systolic and diastolic pressures, and HR were elevated (P less than 0.05) in HDT and N-HDT rats during head-up tilt after 1 day of suspension, while pulse pressures remained un changed. HDT rats exhibited elevated pretilt MAP and failed to respond to rapid head-up tilt with further increase of MAP on day 3, indicating some degree of deconditioning. The whole body suspended rat may be useful as a model to better understand responses of rats exposed to microgravity

Cortical Correlates of the Auditory Frequency-Following and Onset Responses: EEG and fMRI Evidence

The frequency-following response (FFR) is a measure of the brain\u27s periodic sound encoding. It is of increasing importance for studying the human auditory nervous system due to numerous associations with auditory cognition and dysfunction. Although the FFR is widely interpreted as originating from brainstem nuclei, a recent study using MEG suggested that there is also a right-lateralized contribution from the auditory cortex at the fundamental frequency (Coffey et al., 2016b). Our objectives in the present work were to validate and better localize this result using a completely different neuroimaging modality and to document the relationships between the FFR, the onset response, and cortical activity. Using a combination of EEG, fMRI, and diffusion-weighted imaging, we show that activity in the right auditory cortex is related to individual differences in FFR–fundamental frequency (f0) strength, a finding that was replicated with two independent stimulus sets, with and without acoustic energy at the fundamental frequency. We demonstrate a dissociation between this FFR–f0-sensitive response in the right and an area in left auditory cortex that is sensitive to individual differences in the timing of initial response to sound onset. Relationships to timing and their lateralization are supported by parallels in the microstructure of the underlying white matter, implicating a mechanism involving neural conduction efficiency. These data confirm that the FFR has a cortical contribution and suggest ways in which auditory neuroscience may be advanced by connecting early sound representation to measures of higher-level sound processing and cognitive function

Solving biclustering with a GRASP-like metaheuristic: two case-study on gene expression analysis

The explosion of "omics" data over the past few decades has generated an increasing need of efficiently analyzing high-dimensional gene expression data in several different and heterogenous contexts, such as for example in information retrieval, knowledge discovery, and data mining. For this reason, biclustering, or simultaneous clustering of both genes and conditions has generated considerable interest over the past few decades. Unfortunately, the problem of locating the most significant bicluster has been shown to be NP-complete. We have designed and implemented a GRASP-like heuristic algorithm to efficiently find good solutions in reasonable running times, and to overcome the inner intractability of the problem from a computational point of view. Experimental results on two datasets of expression data are promising indicating that this algorithm is able to find significant biclusters, especially from a biological point of view

Increasing Confidence in Evidence-Based Information Gathering for First Year AuD Students

Success of students in Doctor of Audiology programs largely depends on the ability of the learner to find and evaluate scholarly evidence. The purpose of this study is to measure changes in student information gathering confidence and behavior following training in evidence-based information gathering strategies. Results support the hypothesis that understanding foundational concepts in evidence-based practice (EBP) early in the first year of doctoral education allows the learner to gain confidence in information gathering and produce higher quality scholarly output

Using the Assessment Process to Improve Evidence-Based Information Gathering Skills for Future Audiologists

Success of students in Doctor of Audiology programs depends on the ability of the learner to find and evaluate scholarly evidence. The objective of this study is to determine if an information literacy training session on evidence-based information gathering will increase four student measures: (1) Attitudes toward gathering and evaluating scholarly evidence, (2) Knowledge about evidence-base information gathering practices, (3) Perceived value of the training regarding evidence-based searching methods, and (4) Ability to gather evidence for clinical research questions. 23 first-year audiology doctoral students (AuD) at the University of the Pacific in San Francisco participated in this study. Pre- and post-test assessments were given to students before and after a two-hour information literacy training on how to find and evaluate resources during the evidence-based information gathering process. The results support the hypothesis that understanding evidence-based practice (EBP) early in the first year of doctoral education allows the learner to gain confidence in information gathering and produce higher quality scholarly output