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At least 847 records · Page 47Linked to original sources

PubMed2004

Fate of allelopathic substances in space--allelopathy of velvet bean plant and gravity.

Interactions between organisms and species have been long known. It has not been known that the interactive phenomena (allelopathy) may (or may not) differ in space from those on earth. We have studied the gravitational effects on allelopathy by exposing a plant-plant system to pseudo-microgravity, which was generated by a 3D-clinostat. We hypothesized that allelopathy would be modified under altered gravity. L-DOPA (L-3,4-dihydroxyphenylalanine) is known to be the major substance in the allelopathy of velvet bean, released from its root. It has been found that there have been some differences of the allelopathic action of velvet bean plant under pseudo-microgravity. Biosynthesis, release, transport and sensing mechanism associated with allelopathy might be affected by gravity.

Levodopa↗

PubMed2004

Responses of neuromuscular systems under gravity or microgravity environment.

Hindlimb suspension of rats induces induces fiber atrophy and type shift of muscle fibers. In contrast, there is no change in the cell size or oxidative enzyme activity of spinal motoneurons innervating muscle fibers. Growth-related increases in the cell size of muscle fibers and their spinal motoneurons are inhibited by hindlimb suspension. Exposure to microgravity induces atrophy of fibers (especially slow-twitch fibers) and shift of fibers from slow- to fast-twitch type in skeletal muscles (especially slow, anti-gravity muscles). In addition, a decrease in the oxidative enzyme activity of spinal motoneurons innervating slow-twitch fibers and of sensory neurons in the dorsal root ganglion is observed following exposure to microgravity. It is concluded that neuromuscular activities are important for maintaining metabolism and function of neuromuscular systems at an early postnatal development and that gravity effects both efferent and afferent neural pathways.

Afferent Pathways↗

PubMed2004

Life history of amphibians and gravity.

Anurans hold a unique position in vertebrate phylogeny, as they made the major transition from water to land. Through evolution they have acquired fundamental mechanisms to adapt to terrestrial gravity. Such mechanisms are now shared among other terrestrial vertebrates derived from ancestral amphibians. Space research, using amphibians as a model animal, is significant based on the following aspects: (1) Anuran amphibians show drastic changes in their living niche during their metamorphosis. Environments for tadpoles and for terrestrial life of frogs are quite different in terms of gravity and its associated factors. (2) Certain tadpoles, such as Rhacophorus viridis amamiensis, have a transparent abdominal wall. Thus visceral organs and their motion can be observed in these animals in non-invasive manner through their transparent abdominal skin. This feature enables biologists to evaluate the physiological state of these amphibians and study the autonomic control of visceral organs. It is also feasible for space biologists to examine how such autonomic regulation could be altered by microgravity and exposure to the space environment.

Amphibians↗

PubMed2004

Is water immersion useful for analyzing gravity resistance responses in terrestrial plants?

Water immersion has been used as a simulator of microgravity for analyzing gravity responses in semiaquatic plants such as rice. To examine whether or not water immersion for a short experimental period is a useful microgravity simulator even in terrestrial plants, we analyzed effects of water immersion on the cell wall rigidity and metabolisms of its constituents in azuki bean epicotyls. The cell wall rigidity of epicotyls grown underwater was significantly lower than that in the control. Water immersion also caused a decrease in molecular mass of xyloglucans as well as the thinning of the cell wall. Such changes in the mechanical and chemical properties of the cell wall underwater were similar to those observed in microgravity conditions in space. These results suggest that water immersion for a short period is a useful system for analyzing gravity resistance responses even in terrestrial plants.

Cell Wall↗

PubMedDate not supplied

[The biomechanic criterium of adequacy of the modelled and natural force of gravity].

A proposed criterion of the adequacy of modeled (short radius centrifugation) and natural force of gravity (direct problem) helped to the statement and resolution of a reverse simulation problem in calculation of the SRC rotation speed as a function of subject's height with the zero difference in the adequacy criterion The model is fulfiled as a doctor's interface for computational experiments. It was shown that SRC should be rotated at 2 g to reproduce the natural force of gravity for medium-height human subjects (180 cm).

Aerospace Medicine↗

PubMed2005

Sagittal plane alignment of the spine and gravity: a radiological and clinical evaluation.

Analysis of the sagittal balance of the spine includes the study of the spinal curves and of the pelvis in the sagittal plane. It therefore requires full-spine lateral radiographs. The sagittal balance of the spine was studied in forty-nine young adults. Strong correlations were observed between parameters related to the pelvis ("pelvic incidence angle", "sacral slope" and "pelvic tilting"), and the sagittal spinal curves ("lordosis" and "kyphosis"). We therefore propose to begin the evaluation of the sagittal plane alignment of the spine in clinical practice with measurement of the pelvic incidence angle. The relationship between the pelvic incidence angle and the sacral slope, as well as between the sacral slope and lordosis, is then assessed, and these are related to each other. The use of a graphic abacus facilitates assessment of the physiological comparison of the measured values and of the relationship between pelvic and spinal parameters, within their range of physiological variability. This analysis of the sagittal alignment of the spine also considers its dynamic aspect and the importance of gravity load and of muscular contraction on the lumbar structures. These data have been published previously and are recalled here. Three basic patterns of disruption of the relations between parameters may be encountered: a sacral slope angle exceeding the value expected considering the measured pelvic incidence angle (owing to fixed flexion contracture of the hips), excessive lordosis with regard to the observed sacral slope angle (with hyperkyphosis at the thoracic level) and stiff hypolordosis with pelvic retroversion. These three conditions are analysed in the light of the repercussions of the gravity load on the lumbar structures. A convenient method is thus available for functional analysis of the sagittal balance of the spine.

Adult↗

PubMed2004

Fluorescent and dispersion experiments on biological membranes under micro-gravity.

Almost all biological processes, especially those involved in signal reception and signal transduction, depend on the physical and physiological properties of biological membranes. It has been shown, that neuronal tissue and the speed of the action potential (AP) which is the basic neuronal unit of all nervous activity, is sensitive to changes in gravity as well as to other weak external forces. We strongly suppose the membrane to be the most important factor in gravitational responses although it is very difficult to observe the effects of gravity changes on these fragile thermodynamic systems. Therefore we developed two different experiments to measure the structural changes and the lateral membrane tension of spheroid cells under microgravity.

Animals↗

PubMed2004

Protein patterns of the Brassica rapa ovules and seeds under altered gravity.

Electrophoretic investigation of protein patterns of Brassica rapa L. ovules and seeds from plants grown under clinorotation and in the laboratory control was carried out. Ovules at different stages (7 and 18 days after pollination) and mature seeds were analyzed. Polymorphism of seed storage proteins of B. rapa was taken into consideration in analysis of changes in ovule protein patterns under clinorotation. The appearance of a protein component in the region of about 43 kDa was detected in protein patterns of 7-day-old and 18-day-old ovules in the clinostat variants. Under altered gravity, in 18-day-old ovules, the appearance of a protein in the region of about 70 kDa was also revealed. The appearance of the protein component with the similar mobility (about 43 kDa) in ovules of different age from plants grown at clinorotation suggests that synthesis of this protein may be associated with the plant response to altered gravity. However, the investigation of the nature of this protein and its role requires further research to rule out its appearance because of genotypic differences between ovules of the control and experimental variants.

2S Albumins, Plant↗

PubMed2006

Gravity sedimentation of leukocytes is partially independent from erythrocyte sedimentation.

Leukocyte function tests are suitable for monitoring the severity of chronic inflammatory and acute infectious diseases. The tests usually require time consuming leukocyte separation techniques while the original character of leukocytes can substantially alter. In contrast, we noted that gravity sedimentation properties of leukocytes is simple to measure and it also reflects non-specific inflammatory reactions of leukocytes. Our novel test is named leukocyte antisedimentation rate (LAR) which is measured by leukocyte counting in the upper (U) and lower (L) half of the sedimentation blood column after one-hour gravity sedimentation of the whole blood. The formula LAR=100.(U-L)/(U+L) is used to calculate the percentage of leukocytes crosses the middle line of sedimentation blood column upward during one-hour sedimentation (normal range<15%, inter-assay coefficient of variation<5%). In this study we found that in vitro pre-treatment of septic patients' blood samples with protamine, lidocaine and prednisolone decreased leukocyte antisedimentation rate in a concentration dependent manner without effecting erythrocyte sedimentation rate. Leukocyte adherence was measured by the retention rate of leukocytes in a nylon fibre column. There was a significant positive correlation between leukocyte antisedimentation rate and leukocyte adherence (p<0.01), hematocrit (p<0.05), erythrocyte sedimentation rate (p<0.05) when blood samples of 35 healthy individuals were analysed. We concluded that leukocyte antisedimentation rate in septic patients is significantly elevated comparing to healthy controls and as a bedside test it can reflect leukocyte involvement in infections. In vitro protamine, lidocaine and prednisolone pre-treatment of septic patients' blood samples indicates that leukocyte antisedimentation process is partially independent from the ongoing erythrocyte sedimentation.

Adult↗

PubMedDate not supplied

[Evaluation of the appropriateness of hospital admissions using the iso-gravity classification systems APR-DRG and Disease Staging and the Italian version of Appropriateness Evaluation Protocol (AEP)].

Our main purpose was to evaluate the organizational appropriateness of admissions made in a university hospital, by comparing two iso-gravity classification systems, APR-DRG and Disease Staging, with the Italian version of AEP (PRUO). Our analysis focused on admissions made in 2001, related to specific Diagnosis Related Groups (DRGs), which, according an Italian Law, would be considered at high risk of inappropriateness, if treated as ordinary admissions. The results obtained by using the 2 classification systems did not show statistically significant differences with respect to the total number of admissions. On the other hand, some DRGs showed statistically significant differences due to different algorithms of attribution of the severity levels used by the two systems. For almost all of the DRGs studied, the AEP-based analysis of a sample of medical records showed an higher number of inappropriate admissions in comparison with the number expected by iso-gravity classification methods. The difference is possibly due to the percentage limits of tolerability fixed by the Law for each DRG. Therefore, the authors suggest an integrated use of the two methods to evaluate organizational appropriateness of hospital admissions.

Diagnosis-Related Groups↗

PubMedDate not supplied

[The individual prognosis of the gravity and of the outcome of acute radiation disease based on immunological indexes].

The information significance of the immunological indexes for the prognosis of gravity of course and of outcome of an acute radiation disease for the people after the exposure of ionizing radiation in clinically significant doses is studied. The value of indexes of the C-reactive protein contents, of the complement contents and of the titer of haemagglutinins in serum of a blood of 147 patients damaged at Chernobyl NPP accident as a result of external radiation gamma-exposure in combination with internal irradiation from the incorporation in an organism predominantly beta-emitting radionuclides were compared to the weight of acute radiation disease and its outcome (survival or loss). Was determined, that indexes of the contents of C-reactive protein in a peripheral blood during primary reactions on the irradiation (1-2 day after irradiation) and in latent period of disease (3-9 day after irradiation), and also titer of a complement on 3-9 day after irradiation can serve a source of information for the prognosis of probable gravity of a radiation injury and its outcome at irradiation of the man in clinically significant doses.

Acute Disease↗

PubMedDate not supplied

[Dynamics of ECG voltage in changing gravity].

Comparative analysis of the QRS voltage response to gravity variations was made using the data about 26 normal human subjects collected in parabolic flights (CNERS-AIRBUS A300 Zero-G, n=23; IL-76MD, n=3) and during the tilt test (head-up tilt at 70 degrees for a min and head-down tilt at-15 degrees for 5 min, n=14). Both the parabolic flights and provocative tilt tests affected R-amplitude in the Z lead. During the hypergravity episodes it was observed in 95% of cases with the mean gain of 16% and maximal--56%. On transition to the horizontal position, the Rz-amplitude showed a rise in each subject (16% on the average). In microgravity, the Rz-amplitude reduced in 95% of the observations. The voltage decline averaged 18% and reached 49% at the maximum. The head-down tilt was conducive to Rz reduction in 78% of observations averaging 2%. Analysis of the ECG records under changing gravity when blood redistribution developed within few seconds not enough for serious metabolic shifts still revealed QRS deviations associated exclusively with the physical factors, i.e., alteration in tissue conduction and distance to electrodes. Our findings can stand in good stead in evaluation of the dynamics of predictive ECG parameters during long-term experiments leading to changes as in tissue conduction, so metabolism.

Adaptation, Physiological↗

PubMed1990

Binding of alpha-fetoprotein by immobilized monoclonal antibodies during episodes of zero-gravity obtained by parabolic flight.

Alpha-fetoprotein (AFP), a single chain polypeptide which is synthesized by the liver and yolk sac of the human fetus, provided a model ligand for assessing the effects of microgravity on ligand binding to surface-immobilized model receptor molecules. Monoclonal antibodies, used as receptors for AFP, were immobilized by covalent attachment to latex microparticles. Zero gravity environment was obtained by parabolic flight aboard NASA 930, a modified KC-135 aircraft. During the onset of an episode of zero gravity, ligand and receptor were mixed. Timed incubation (20 s) was terminated by centrifugation, the supernatant removed, and microparticles were assessed for bound AFP by immunochemical methods. The extent of binding was not influenced by microgravity, when compared with 1-G controls, which suggests that aberrant cellular activities observed in microgravity are not the simple expression of altered macromolecular interactions.

Antibodies, Monoclonal↗

PubMed2006

[Pulmonary atelectasis in patients with neurological or muscular disease; gravity-related lung compression by the heart and intra-abdominal organs on persistent supine position].

We report 10 cases of pulmonary atelectasis diagnosed by chest computed tomography in patients with neurological or muscular disease. Atelectasis was frequently seen in hypotonic patients who could not roll over on their own. The atelectases located mostly in the dorsal bronchopulmonary segments, adjacent to the heart or diaphragm. Atelectasis diminished in two patients after they became able to roll themselves over. Gravity-related lung compression by the heart and intra-abdominal organs on persistent supine position can cause pulmonary atelectasis in patients with neurological or muscular disease who can not roll over by their own power. To confirm that the prone position reduces compression of the lungs, chest computed tomography was performed in both the supine and the prone position in three patients. Sagittal images with three-dimensional computed tomographic reconstruction revealed significant sternad displacements of the heart and caudal displacements of the dorsal portion of the diaphragm on prone position compared with supine position. The prone position, motor exercises for rolling over, and biphasic cuirass ventilation are effective in reducing gravity-related lung compression. Some patients with intellectual disabilities were also able to cooperate in chest physiotherapy. Chest physiotherapy is useful in preventing atelectasis in patients with neurological or muscular disease.

Abdomen↗

PubMedDate not supplied

Effect of Volume Loading with Water, Normal Saline, Palm Wine and Lipton Tea on Urinary Output, pH, Specific Gravity, Sodium and Potassium Concentrations in Human Subjects.

A comparative study of the diuretic effect of water, normal saline, palm wine and Lipton tea was carried out on forty (40) randomly selected, apparently normal undergraduate students of Medicine and Pharmacy at the University of Uyo, Nigeria. One and a half (1.5) litres of water, normal saline, palm wine and Lipton tea were given on separate days to the same subjects. The subjects were made to void their bladder before ingesting these substances and the urine sample collected was taken as control sample at the time zero. Thereafter, all the subjects emptied their bladder hourly for 3 hours. The urinary output, pH, specific gravity, sodium and potassium concentrations were determined. The results showed that water, palm wine and Lipton tea produced diuresis. Normal saline did not. Reduction of specific gravity and pH of urine accompanied these diuretic effects. Administration of normal saline and Lipton tea caused natriuresis. Potassium sparing diuresis was seen with Lipton tea and palm wine, whereas, water diuresis led to increased levels of potassium in urine. Volume loading with the above substances affected not only urinary output but also renal handling of sodium and potassium ions.

Journal Article↗

PubMed1977

F response and H reflex analysis of physiological unity of gravity and antigravity muscles in man.

Observational differences between reflex (H reflex) and antidromic (F response) activation of segmental motoneurons by a peripheral electrical stimulus are described. In contrast to H reflexes, the percentage of F responses found after a series of stimuli is directly related to the pick-up field of the recording electrode consistent with this response being due to the variable activation of a small fraction of the available motoneuron pool. Despite the differing physiological mechanisms, both F responses and H reflexes can be used to demonstrate similar relative "central excitatory states" for antigravity muscles (i.e. extensors in the lower extremity and flexors in the upper extremity) and their antagonist gravity muscles. H reflexes were elicited not only in their usual location in certain antigravity muscles but also in unusual locations by length/tension changes in agonist and antagonist groups as well as by passive stretch. The data argue for the physiological unity of similarly acting gravity and antigravity muscles as well as supporting a meaningful role of group II afferents in normal segmental motoneuron pool excitability.

Adult↗

PubMedDate not supplied

Experimental development of a fixed volume, gravity draining, prosthetic urinary bladder.

A fixed volume, semi-rigid, gravity draining prosthetic urinary bladder has been developed in experimental animals. The conceptual model demands: 1) an encrustation resistant lumenal surface; 2) successful urothelial-prosthesis and bowel-prosthesis anastomoses; 3) a transcutaneous abdominal wall prosthesis that bonds with skin, muscle, bladder, and peritoneum which resists external and intraluminal bacterial challenge; and 4) an air permeable, fluid impermeable filter which allows passive filling and gravity evacuation of urine. The principles involved have been successfully tested in rodents, rabbits, swine, and dogs. To date two total alloplastic prosthetic bladders fabricated from Biolor II and Proplast have been inserted in mini-swine for 4 weeks.

Animals↗

PubMed1988

Exercise during gravity inversion: acute and chronic effects.

The purpose of this study was to determine whether gravity inversion could correctly be called an exercise, and whether inversion and inverted exercise produced safe blood pressure responses. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and oxygen consumption (VO2) were measured in 19 healthy young men (means = 20.31 years) in seven positions: (1) standing passive (STD), (2) inverted passive (INV), (3) standing recovery postpassive inversion (SRPI), (4) standing exercise (SDE), (5) standing recovery poststanding exercise (SRPSE), (6) inverted exercise (INVE), and (7) inverted recovery postinverted exercise (IRPIE). Ten of the subjects participated in a five-week inversion training program, after which all 19 subjects were retested. Compared to STD, INV elicited significant increases in SBP/DBP and a significant decrease in HR. The average INV blood pressure was 146/97 mmHg, which was further increased during INVE to 158/101 mmHg. These responses increase the workload of the heart and may be dangerous to some populations. No physiologic adaptations occurred in any of the inverted positions as a result of inversion training. Gravity inversion should not be compared to or classified as an exercise. Some previously suggested inverted exercises are not recommended. Because of the nature of the responses, medical screening before the use of inversion devices is critical.

Adult↗