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At least 1,117 records · Page 62Linked to original sources
PubMed2006

A comparison of epidural pressures and incidence of true subatmospheric epidural pressure between the mid-thoracic and low-thoracic epidural space.

BACKGROUND: Differences in epidural pressure (EP) may influence the spread of blockade in thoracic epidural anesthesia. We evaluated if EP and the incidence of subatmospheric EP differ between the mid- and low-thoracic epidural space. METHODS: Patients received an epidural catheter at the T3-5 (MID group, n = 20) or T7-10 (LOW group, n = 20) intervertebral space, respectively. The epidural space was identified using a Tuohy needle connected to a pressure transducer, after which EP was measured. RESULTS: The epidural space could not be identified in three patients who were excluded from the study. EP data are presented as median value (interquartile range). Median EP was 1 mm Hg (-1 to 4.5) in the MID group, and 4 mm Hg (2-7.8) in the LOW group (P = 0.04). The incidence of an EP <or=0 mm Hg was 8 of 17 patients in the MID group and 2 of 20 patients in the LOW group (P = 0.02). CONCLUSIONS: We conclude that EP is lower, and the incidence of subatmospheric EP is higher in the mid-thoracic epidural space when compared with that in the low-thoracic epidural space. However, median EP was positive in both groups. It remains to be investigated whether this pressure gradient is sufficient to influence the spread of thoracic epidural blockade.

Adult↗
PubMed1992

The subarachnoid spaces in craniosynostosis.

A review of 85 patients with various forms of craniosynostosis showed predictable patterns of dilatation of the subarachnoid spaces in regions of compensatory skull growth. The characteristic pattern in sagittal synostosis (43 patients) included dilatation of the frontal and occipital subarachnoid spaces associated with the elongation of the anteroposterior dimension of the skull and widening of the interhemispheric fissure. In 11 patients with unilateral coronal synostosis, dilatations of the subarachnoid spaces over the contralateral frontal lobe, the sylvian regions, and the ipsilateral temporal lobe tip were consistent with the skull changes of contralateral frontal bossing, increased bitemporal dimension, and elevation of the sphenoid wing, respectively. Four patients with bilateral coronal synostosis also had enlarged subarachnoid spaces high over the convexities of the brain consistent with the towering configuration of the skull. Four patients with true lambdoid synostosis had dilatation of the subarachnoid space only over the ipsilateral frontal lobe associated with compensatory bossing of the frontal bone. Ten of 14 patients with lambdoid deformities had bilateral enlargement of the subarachnoid spaces suggesting brain atrophy and an underlying motor delay accounting for the position-induced skull changes. The findings suggest that focal hydrodynamic mechanisms are involved in the compensatory skull changes seen in craniosynostosis.

Atrophy↗
PubMed2002

Mutation frequency of plasmid DNA and Escherichia coli following long-term space flight on Mir.

To elucidate the biological influence of space radiation, we studied the effects of long-term space flight on mutation of the bacterial ribosomal protein L gene (rpsL). We prepared dried samples of plasmid DNA and repair-deficient and wild type cells of Escherichia (E.) coli. After a 40-day space flight on board the Russian space station Mir, the mutation frequencies of the rpsL gene were estimated by transformation of E. coli and by assessment of conversion of rpsL wild type phenotype (SmS) to its mutant phenotype (SmR). The experimental findings indicate that mutation frequencies of space samples were not significantly different from those of ground control samples in plasmid DNA and both E. coli strains. It may suggest that space radiation did not influence mutation frequency.

DNA↗
PubMed1999

Management of space problems in the primary and mixed dentitions.

BACKGROUND: According to the Third National Health and Nutrition Examination Survey, crowding and irregularity remain a consistent problem for children. Management of space problems continues to play an important role in a dental practice. It also represents an area of major interaction between the primary provider and the specialists. This article attempts to update clinicians on the current knowledge of space management. DESCRIPTION OF CONDITION: Proper management of space in the primary and mixed dentitions can prevent unnecessary loss in arch length. Diagnosing and treating space problems requires an understanding of the etiology of crowding and the development of the dentition to render treatment for the mild, moderate and severe crowding cases. Most crowding problems with less than 4.5 millimeters can be resolved through preservation of the leeway space, regaining space or limited expansion in the late mixed dentition. In cases with 5 to 9 mm of crowding, some can be approached with expansion after thorough diagnosis and treatment planning. Most of these cases will require extraction of permanent teeth to preserve facial esthetics and the integrity of the supporting soft tissue. Serial extraction or guidance of eruption is reserved for treatment of severe tooth-size/arch-size discrepancies. Due to variations in the timing and extraction sequence depending on the diagnosis, serial extraction should be reserved for those who can complete the treatment successfully. CLINICAL IMPLICATIONS: The recommended timing of referring patients with moderate crowding to specialists for treatment is in the late mixed-dentition stage of development. Patients with severe crowding will require earlier evaluation for serial extraction.

Adolescent↗
PubMed1986

Kinetic of adjustment of enzyme catalytic concentrations in the extracellular space of the man, the dog and the rat. Approach to a quantitative diagnostic enzymology, V. Communication.

The high degree of constancy of enzyme catalytic activity in the plasma of a given individual is regulated by a complex system of flux equilibria consisting of eight basic processes. Some of these processes are of primarily theoretic importance. Enzymes from all tissues of the body, including the liver, are released via a continuous physiological process into the interstitial space and get into the intravascular space by way of lymphatic transport. The release of enzymes from tissues directly into the intravascular space is of secondary importance as is the exchange of enzyme molecules across capillary membranes from the intravascular to the interstitial space and vice versa. In contrast, enzymes from circulating blood cells are transported directly into the intravascular space. Enzymes are removed from the intravascular space at rates which vary greatly between both enzymes and species. In a review of the literature, half-lives of diagnostically important enzymes in plasma of man, dogs and rats were given and the striking differences in the results for a given enzyme are discussed from a methodological point of view. In a mathematical analysis, data for lymphatic transport of enzymes from dogs and rats (Lindena et al. (1986) this J. 24, 19-33) and of enzyme efflux from in vivo ageing erythrocytes (Lindena et al. (1986) this J. 24, 49-59) into the plasma are related to the elimination rate constants of enzymes from the plasma. The contribution of lymphatically transported enzymes to the basal catalytic activity in plasma (Lindena & Trautschold (1986) this J. 24, 11-18) amounts to 55-80% for lactate dehydrogenase and malate dehydrogenase, 80-90% for adenylate kinase and phosphohexose isomerase, 90-95% for aspartate aminotransferase and aldolase and 99% for creatine kinase. A model of Ca2+ -mediated vesicular transport of enzymes out of ageing erythrocytes is proposed. The importance of lymphatically transported enzymes to total plasma catalytic activity in dogs and rats argues for a similar contribution of lymph transport in man.

Animals↗
PubMed2005

Biomarkers of space radiation risk.

Radiation risk estimates are based on epidemiological data obtained on Earth for cohorts exposed predominantly to acute doses of gamma rays, and the extrapolation to the space environment is highly problematic and error-prone. The uncertainty can be reduced if risk estimates are compared directly to space radiation-induced biological alterations, i.e. by detecting biomarkers in astronauts. Chromosomal aberrations in peripheral blood lymphocytes are the only biomarker that can provide simultaneous information on dose, dose equivalent and risk, and they have been measured extensively in astronauts during the past 10 years. Individual relative risks calculated from chromosomal aberration measurements in crew members after single space missions in low-Earth orbit fall in the same range as the estimates derived from physical dosimetry, suggesting that the current system for radiogenic risk evaluation is essentially sound. However, the output of the biomarker test is dependent upon the sampling time. Recent results show a fast time-dependent decay of chromosomal aberrations in blood lymphocytes after space flight and a lack of correlation between translocations and cumulative dose in astronauts involved in two to five space missions. This "time factor" may reflect individual variability and time dependence in the risk produced by exposure to cosmic radiation during the flight. Biomarkers may be superior to dose in predicting space radiation risk, pending technical improvements in sensitivity, and validation by epidemiological studies.

Biomarkers↗
PubMed2004

Development and swimming behavior of Medaka fry in a spaceflight aboard the Space Shuttle Columbia (STS-107).

A space experiment aimed at closely observing the development and swimming activity of medaka fry under microgravity was carried out as a part of the S*T*A*R*S Program, a space shuttle mission, in STS-107 in January 2003. Four eggs laid on earth in an artificially controlled environment were put in a container with a functionally closed ecological system and launched on the Space Shuttle Columbia. Each egg was held in place by a strip of Velcro in the container to be individually monitored by close-up CCD cameras. In the control experiment, four eggs prepared using the same experimental set-up remained on the ground. There was no appreciable difference in the time course of development between space- and ground-based embryos. In the ground experiment, embryos were observed to rotate in place enclosed with the egg membrane, whereas those in the flight unit did not rotate. One of the four eggs hatched on the 8th day after being launched into space. All four eggs hatched in the ground unit. The fry hatched in space was mostly motionless, but with occasional control of its posture with respect to references in the experimental chamber. The fry hatched on ground were observed to move actively, controlling their posture with respect to the gravity vector. These findings suggest that the absence of gravity affects the initiation process of motility of embryos and hatched fry.

Animals↗
PubMed2005

Space exercise and Earth benefits.

The detrimental impact of long duration space flight on physiological systems necessitates the development of exercise countermeasures to protect work capabilities in gravity fields of Earth, Moon and Mars. The respective rates of physiological deconditioning for different organ systems during space flight has been described as a result of data collected during and after missions on the Space Shuttle, International Space Station, Mir, and bed rest studies on Earth. An integrated countermeasure that simulates the body's hydrostatic pressure gradient, provides mechanical stress to the bones and muscles, and stimulates the neurovestibular system may be critical for maintaining health and well being of crew during long-duration space travel, such as a mission to Mars. Here we review the results of our studies to date of an integrated exercise countermeasure for space flight, lower body negative pressure (LBNP) treadmill exercise, and potential benefits of its application to athletic training on Earth. Additionally, we review the benefits of Lower Body Positive Pressure (LBPP) exercise for rehabilitation of postoperative patients. Presented first are preliminary data from a 30-day bed rest study evaluating the efficacy of LBNP exercise as an integrated exercise countermeasure for the deconditioning effects of microgravity. Next, we review upright LBNP exercise as a training modality for athletes by evaluating effects on the cardiovascular system and gait mechanics. Finally, LBPP exercise as a rehabilitation device is examined with reference to gait mechanics and safety in two groups of postoperative patients.

Bed Rest↗
PubMed1995

Fish mating experiment in space--what it aimed at and how it was prepared.

The code name 'MEDAKA' was given to the fish experiment in the IML-2 (the second International Microgravity Laboratory), a Space-shuttle mission (STS-65) carried out in July 1994. Medaka is the Japanese name for a small fresh-water fish, Oryzias latipes. This experiment titled 'Mating behavior of the fish Medaka and development of their eggs in space' aimed to present data for designing the future fish-culture in space. The Medaka experiment accomplished its objectives to the point of 100%. The fish mated, laid eggs in space, and these eggs developed normally to hatching (coming out as a baby fish) under microgravity. Its success totally depended on selection of the four fish sent to space. This paper describes the aims of the IML-2 Medaka fish experiment and how it was prepared, together with a brief report on what were achieved in space.

Animals↗
PubMed1998

Echodense spinal subarachnoid space in neonates with progressive ventricular dilatation: a marker of noncommunicating hydrocephalus.

OBJECTIVE: Our purpose was to evaluate the frequency and clinical significance of echogenic debris in the spinal subarachnoid space of neonates at risk for progressive ventricular dilatation. SUBJECTS AND METHODS: Spinal sonography was performed on 15 neonates with severe intracranial hemorrhage (n = 10) or bacterial meningitis (n = 5). Spinal sonography also was performed on 16 control neonates. Images were analyzed for the presence and location of echogeric debris within the thoracolumbar subarachnoid space. Lumbar punctures were performed on all 31 neonates, and CSF was analyzed for cell count and protein content. Ten of 15 neonates required ventricular drainage procedures. RESULTS: Progressive ventricular dilatation occurred in 11 of 15 neonates with intracranial hemorrhage or meningitis. Echogenic debris was present in the thoracolumbar subarachnoid space on spinal sonography in every neonate with progressive ventricular dilatation compared with none of the 16 control neonates (p < .0001 by chi-square analysis). In addition, the 11 neonates with echogenic subarachnoid space had significantly higher protein and RBC contents in the lumbar CSF (p < .04). CONCLUSION: Echogenic subarachnoid space revealed by sonography is associated with progressive ventricular dilatation after severe intracranial hemorrhage or bacterial meningitis and is caused by high protein and RBC contents in the subarachnoid space. This finding may be helpful in identifying neonates who will not benefit from serial lumbar punctures for treatment of hydrocephalus.

Case-Control Studies↗
PubMed2006

Effect of floor space during transport of market-weight pigs on the incidence of transport losses at the packing plant and the relationships between transport conditions and losses.

Data on 74 trailer loads of finishing pigs (mean BW = 129.0, SEM = 0.63 kg) from wean-to-finish buildings on 2 farms within 1 production system were collected to investigate the effect of amount of floor space on the trailer (0.39 or 0.48 m2/pig) during transport on the incidence of losses (dead and nonambulatory pigs) at the packing plant and to study the relationships between transport conditions and losses. Pigs were loaded using standard commercial procedures for pig handling and transportation. Two designs of flat-deck trailers with 2 decks were used. Floor space treatments were compared in 2 similarly sized compartments on each deck of each trailer type. Differences in floor space were created by varying the number of pigs in each compartment. The incidence of nonambulatory pigs at the farm during loading and at the plant after unloading, average load weight, load number within each day, event times, and temperature and relative humidity in the trailer from loading to unloading were recorded. Of the 12,511 pigs transported, 0.26% were non-ambulatory at the farm, 0.23% were dead on arrival, and 0.85% were nonambulatory at the plant. Increasing transport floor space from 0.39 to 0.48 m2/pig reduced the percentage of total nonambulatory pigs (0.62 vs. 0.27 +/- 0.13%, respectively; P < 0.05), nonambulatory, noninjured pigs (0.52 vs. 0.15 +/- 0.11%, respectively; P < 0.01), and total losses (dead and nonambulatory pigs) at the plant (0.88 vs. 0.36 +/- 0.16%, respectively; P < 0.05) and tended to reduce dead pigs (0.27 vs. 0.08 +/- 0.08%, respectively; P = 0.06). However, transport floor space did not affect the percentage of nonambulatory, injured pigs at the plant. Nonambulatory pigs at the farm were positively correlated with relative humidity during loading and load number within the day (r = 0.46 and 0.25, respectively; P < 0.05). The percentage of total losses at the plant was positively correlated to waiting time at the plant, unloading time, and total time from loading to unloading (r = 0.24, 0.51, and 0.36, respectively; P < 0.05). Average temperature during loading, waiting at the farm, transport, waiting at the plant, unloading, and average pig weight on the trailer were not correlated to losses. These results suggest that floor space per pig on the trailer and transport conditions can affect transport losses.

Animal Husbandry↗
PubMed2002

Spacing effects in cued-memory tasks for unfamiliar faces and nonwords.

Memory for repeated items improves as the interval between repetitions in a list increases (the spacing effect). This study investigated the spacing effect in recognition memory and in a frequency judgment task for unfamiliar target faces that were repeated in the same or in a different pose during incidental learning. Changing the pose between prime and probe trials reduced perceptual repetition priming in a structural discrimination task and also reduced the spacing effect in a subsequent unexpected recognition memory task. Three further experiments confirmed that the spacing effect inrecognition memory (Experiments 2 and 4) or frequency judgment (Experiment 3) was reduced when the pose was changed between repeated presentations at study. Similarly, with nonwords as targets (Experiment 5), changing the font between repeated occurrences of targets at study removed the spacing effect in a subsequent unexpected recognition memory test. These results are interpreted to support the view that short-term perceptual repetition priming underlies the spacing effect in explicit cued-memory tasks for unfamiliar nonsense material.

Adult↗
PubMed1976

Added apparatus dead space in the N2-closing volume test: - a refinement or a bias.

14 subjects without symptoms of cardiopulmonary disease underwent paired closing volume determinations by the modified single breath nitrogen test. Measurements were performed with an apparatus dead space of approximately 40 ml and approximately 350 ml. A rise in closing volume percent for all subjects was found in measurements with dead space of 350 ml. This Difference was statistically significant at the 0.001 level for the group as a whole. No change in the accuracy of the method, expressed as the standard deviation of each subjects values with and without added dead space cojld be demonstrated. Linear regression analysis of the closing volume percent values measured with added dead space as a function of closing volume percent values measured without added dead space showed the expected highly significant positive correlation. However the regression line was not parallel to line of identity, indicating that the higher the initial value of closing volume percent the higher rise after addition of apparatus dead space. With reference to characterizing a person as normal or abnormal this could be considered a refinement of the method.

Adult↗
PubMed1998

[A new way for neural transplantation: the grafted central neurons migration from the subarachnoid space into the spinal cord and cerebral cortex].

In the studies of neural transplantation, Chen and his colleagues observed that the grafted central neurons could migrate from the subarachnoid space into the spinal cord and cerebral cortex. This finding promises an attractive possibility that a lot of neurons might be introduced into a long distance of the spinal cord and the extensive superficial layer of the brain which has suffered neuronal loss and thus might reinnervate a wide range of denervated area. Female rats were used in the study. Neural tissues or cell suspension containing fetal monoaminergic or arginine vasopressin (AVP) neurons were implanted into the subarachnoid space of the transected spinal cord or the normal brain and spinal cord. The rats were treated in different ways: some were grafted and the spinal cord was cut at the same time; grafted one month later or before the spinal cord was cut; grafted but the brain and spinal cord remained intact. Immunohistochemical method was used to monitor the grafted neurons after these rats survived for one or nine months. The results showed that there were a few to hundreds of 5-HT, TH or AVP-immunoreactive neurons and fibers found in the spinal cord or cerebral cortex near the grafted region. These neurons grew well and displayed their capacity of adaptability and long-time survival in the host CNS. No neurons, however, were found in the subarachnoid space of the grafted rats which had survived for another month or longer. On the other side, grafted with tissue block, it was found that transplants left in the grafted region grew as a "nodule" attaching to the surface of the spinal cord. The "nodule" was also found occasionally when the cell suspension was centered heavily at one region of the subarachnoid space. In both cases, the pia mater between them disappeared. Immunoreactive neurons were found in the "nodule" and neighboring spinal cord, some fibers from the neurons in the "nodule" extended into the spinal cord. It is supposed that a part of cells in the suspension died after grafted in the subarachnoid space and released hydrolases which injured the near pia mater by hydrolysis. As a result, some neurons in the suspension had a chance to migrate into the spinal cord and cerebral cortex. After the transplant in the subarachnoid space was gradually cleaned out, the enzymatic hydrolysis to the pia mater became weaker and finally stopped, the lesioned pia mater was gradually repaired. If the transplant was not cleared timely, the pia mater could not withstand the persistent hydrolysis and collapsed finally, leading the transplant to be fused with the host CNS.

Animals↗
PubMed2001

[Development of a cultivation technology and selection of leaf vegetable cultures for space greenhouse].

We plan to perform space experiments on development of a technology for cultivation of leaf vegetables that might be a component of future life support systems for space crews. For this purpose, we are going to fly research greenhouses with the crop area from 0.03 up to 0.1 m2 inside the universal docking module of the ISS Russian segment. To prepare for future space experiments, ground investigations were made in order to compare crop capacity of various artificial soils used to grow leaf vegetables in greenhouse Svet. Useful life of root module Svet can be extended with a new technology based on resupply of fibrous substrate with nutrients. The most effective volume of soil per a plant was determined which sustains high productivity of leaf vegetables in Svet. To select leaf vegetables for in-space cultivation, we conducted investigations of productivity, morphometric and biochemical characteristics, and palatability of 18 cultures including alternative greens highly popular in Japan and China which have been earlier tested neither in laboratory nor in space within the closed eco-system projects. We would prioritize mizuna, pak choi, tatsoi, rapina or broccoli raab, and red giant mustard as objects for in-space investigations.

Agrochemicals↗
PubMed1993

Psychophysiological aspects of increasing resistance to space motion sickness.

One of the actual and difficulty solved problems of the adaptation period to microgravitation is space motion sickness (MS) that has the negative influence on well-being and performance of crewmembers in the initial and highly crucial phase of the orbital flight. Among the prophylactic measures for decrease of the unfavourable influence of space MS the preflight training is of great importance, and its role in perspective undoubtedly will grow in connection with increase of the number of crewmembers. During the last years several authors received experimental materials evidenced that as a base of more effective increase of resistance to space MS there may be used adequate modelling of the main physiological effects of the adaptation period to microgravitation. In the most investigations the main attention is paid to modelling of "conflicting" vestibular-visual (VV) impacts. In other hand, in connection with the contradictory materials about the role of hemodynamic component in the development of space MS this effect of microgravitation conditions, as a rule, is not modelled in the methods of resistance enhancement to space MS. Hence in this work there was put a task to investigate the efficiency of application of different combination of VV-impacts and creation of redistribution of liquid medium of an organism in the cranial direction for increase of man resistance to space MS. For resolving this task there was used the specially developed stand, made in two modifications. This stand provided redistribution of liquid medium of an organism in the cranial direction by putting the investigated individual into the antiorthostatic position (AOP). During the rotation around the vertical axis individual was placed in such supine position on the turn table that labyrinth of the inner ear should be displaced by 8-10 centimeters from the axis of rotation to the head edge of the turn table. This increased the adequacy of vestibular apparatus irritation by gravitation and inertia forces with regard to microgravitation conditions.

Adaptation, Physiological↗
PubMed1996

Space stress and genome shock in developing plant cells.

In the present paper I review symptoms of stress at the level of the nucleus in cells of plants grown in space under nonoptimized conditions. It remains to be disclosed to what extent gravity "unloading" in the space environment directly contributes to the low mitotic index and the chromosomal anomalies and damage that is frequently, but not invariably, demonstrable in space-grown plants. Evaluation of the available facts indicates that indirect effects play a major role and that there is a significant biological component to the susceptibility to stress damage equation as well. Much remains to be learned on how to provide strictly controlled, optimal environments for plant growth in space. Only after optimized controls become possible will one be able to attribute any observed space effects to lowered gravity or to other significant but more indirect effects of the space environment.

Cell Cycle↗
PubMed1997

Noninvasive methods in space cardiology.

The development and application of noninvasive methods in space cardiology is discussed. These methods are used in astronautics both to gain new insights into the impact of weightlessness conditions on the human organism and to help solve problems involved in the medical monitoring of space crew members. The cardiovascular system is a major target for the action of microgravity. Noninvasive methods used to examine the cardiovascular system during space flights over the past 30 years are listed. Special attention is given to methods for studying heart rate variability and contactless recording of physiologic functions during night sleep. Analysis of heart rate variability highlights an important principle of space cardiology-gaining the maximum amount of information while recording as little data as possible. With this method, the degree of strain experienced by the systems of autonomic regulation and the adaptational capabilities of the body can be assessed at various stages of a space flight. Discriminant analysis of heart rate variability data enables the psycho-emotional component of stress to be separated from the component associated with the impact of weightlessness. A major advance in space medicine has been the development of techniques for contactless recording of pulse rates, breathing frequency, myocardial contractility, and motor activity during sleep using a sensor installed on the cosmonaut's sleeping bag. The data obtained can be used to study ultradian rhythms, which reflect the activity of higher autonomic centers. An important role of these centers in mobilizing functional reserves of the body to ensure its relatively stable adaptation to weightless conditions is shown.

Aerospace Medicine↗