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PubMedDate not supplied

[State of the thyroid gland C-cells in rats after a flight on Kosmos-type biosatellites (based on morphological study data)].

Calcitonin-secreting cells (C-cells) of the thyroid glands from 51 SPF Wistar rats flown for 18.5 to 22 days aboard biosatellites Cosmos-605, 782 and 936 and sacrificed 4.5--13 hours, 1--2 and 25--27 days after recovery were examined histologically and karyometrically. Vivarium (57) and synchronous (58) rats were used as controls. Variations in the nuclear volume of C-cells and their density were shown to depend on the experimental conditions and time interval elapsed after recovery. Morphological changes in C-cells were assumed to be associated with alterations in calcium metabolism during an exposure of rats to weightlessness, artificial gravity and Earth gravity.

Animals↗

PubMedDate not supplied

[Immune and microcirculatory disorders and their correction in the participants in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station who have neurosomatic pathology].

A study was made of the immune status as well of microhemodynamics in those 312 patients presenting with neurosomatic pathologies who had taken part in the elimination of aftereffects of Chernobyl NPP accident. The degree of alterations in immunity and microcirculation was found to be associated with the gravity of cerebrovascular and concurrent gastrointestinal pathologies. Use in a combined treatment of ultraviolet-radiated blood, laser irradiation of blood as well as administration of parmidine permit rapid elimination of the abnormalities revealed. An association was established between values for immunity and those for microcirculation, which fact pathogenetic interrelationship between these findings.

Adult↗

PubMed2001

New substances for intraocular tamponades: perfluorocarbon liquids, hydrofluorocarbon liquids and hydrofluorocarbon-oligomers in vitreoretinal surgery.

UNLABELLED: Perfluorocarbon liquids (PFCLs) and heavy fluorocarbon liquids (HFCLs) are being increasingly used as soft tools during vitreoretinal surgery. However, since long-term intraocular tolerance is still unsatisfactory, at present complete removal at the end of surgery is recommended. With the aim to improve long-term intraocular compatibility and to enlarge the spectrum of clinical applications, modified HFCLs have been developed. HFCL-oligomers with a higher viscosity represent the latest perspective. All three groups of fluorocarbon liquids will be compared with respect to their physical and chemical properties, experimental and clinical results, and prospects for clinical applications. Common features of PFCLs, HFCLs and HFCL-oligomers are biological inertness, specific gravity higher than water, immiscibility with water or blood, and a high gas binding capacity. In PFCLs such as decalin, octane, or phenanthrene. All carbon atoms of the carbon backbone are completely fluorinated. In experimental and clinical use, emulsification, vascular changes and structural alterations of the retina have been described. By only partial replacement of hydrogen atoms by fluorine, the specific gravity of HFCLs is reduced, whereas lipophilic properties increase. Thus HFCLs are potential solvents for intraocular silicone oil remnants. However. after long-term application, side-effects are similar to those observed with PFCLs. Substances of this group, such as F6H6, F6H8, 044, and 062 are used intraoperatively and are currently being investigated for clinical long-term application. With the aim to avoid emulsification and to improve intraocular tolerance, we have developed HFCL-oligomers consisting of 2-4 HFCL molecules with increased viscosity. The oligomers were tolerated well in rabbit eyes for up to 4 months. In contrast to PFCLs or monomers, they did not emulsify nor show vascular alterations. ERGs returned to normal after removal of the oligomer from the eye. Histology of the retina showed mild alterations. CONCLUSION: according to physical properties, experimental intraocular compatibility and stability against emulsification, HFCL-oligomers are promising candidates for improved long-term tamponade of the lower retina. At present, indications for an application in human eyes have to be determined in clinical trials.

Animals↗

PubMed1984

Relationship between specific gravity, water content, and serum protein extravasation in various types of vasogenic brain edema.

Vasogenic brain edema was induced in cats by cold injury (six animals), brain tumors (five animals), and brain abscesses (six animals). Water and electrolyte content, specific gravity, blood volume, and the amount of extravasated serum proteins were determined in small tissue samples taken from gray and white matter at various distances from the lesion. Edema was strictly confined to the white matter of the affected hemisphere and declined from the lesion to the more peripheral regions. It was characterized by the extravasation of serum proteins and an increase of water and sodium content with little or unpredictable changes of potassium and blood volume. The calculated sodium content of edema fluid varied between 129 and 135 mueq/ml, and serum protein content between 8.1 and 11.9 mg/ml. In all three types of edema, specific gravity and water content correlated closely with the same slope and intercept of the calculated regression (y = 1.119-0.0011 x, r = -0.91). The results obtained indicate that the main denominator of specific gravity of edematous white matter is water content and that this relationship is not significantly altered by variations of blood volume or serum protein content.

Animals↗

PubMed2001

In vitro modeling of human tibial strains during exercise in micro-gravity.

Prolonged exposure to micro-gravity causes substantial bone loss (Leblanc et al., Journal of Bone Mineral Research 11 (1996) S323) and treadmill exercise under gravity replacement loads (GRLs) has been advocated as a countermeasure. To date, the magnitudes of GRLs employed for locomotion in space have been substantially less than the loads imposed in the earthbound 1G environment, which may account for the poor performance of locomotion as an intervention. The success of future treadmill interventions will likely require GRLs of greater magnitude. It is widely held that mechanical tissue strain is an important intermediary signal in the transduction pathway linking the external loading environment to bone maintenance and functional adaptation; yet, to our knowledge, no data exist linking alterations in external skeletal loading to alterations in bone strain. In this preliminary study, we used unique cadaver simulations of micro-gravity locomotion to determine relationships between localized tibial bone strains and external loading as a means to better predict the efficacy of future exercise interventions proposed for bone maintenance on orbit. Bone strain magnitudes in the distal tibia were found to be linearly related to ground reaction force magnitude (R(2)>0.7). Strain distributions indicated that the primary mode of tibial loading was in bending, with little variation in the neutral axis over the stance phase of gait. The greatest strains, as well as the greatest strain sensitivity to altered external loading, occurred within the anterior crest and posterior aspect of the tibia, the sites furthest removed from the neutral axis of bending. We established a technique for estimating local strain magnitudes from external loads, and equations for predicting strain during simulated micro-gravity walking are presented.

Aged↗

PubMed1994

Effect of hexylene glycol-altered microtubule distributions on cytokinesis and polar lobe formation in fertilized eggs of Ilyanassa obsoleta.

Some effects of gravity on early morphogenesis are correlated with microtubule locations within cells. During first cleavage in Ilyanassa obsoleta embryos, a transitory polar lobe constriction forms and then relaxes, allowing the polar lobe to merge with one daughter cell. If the polar lobe is equally divided or removed, morphogenesis is severely disrupted. To examine microtuble locations during early Ilyanassa development, eggs were fixed and stained for polymerized alpha-tubulin during first cleavage. The mitotic apparatus assembles at the animal pole. The cleavage furrow forms between the asters, constricting to a stabilized intercellular bridge encircling midbody-bound microtubules, whereas the polar lobe constriction forms below and parallel to the spindle, constricting to a transitory intercellular bridge encircling no detectable microtubules. At metaphase an alpha-tubulin epitope is distributed throughout the spindle, whereas a beta-tubulin epitope is present predominantly in the asters. Incubation in hexylene glycol, a drug that increases microtubule polymerization, during mitosis causes the polar lobe constriction to tighten around polymerized alpha-tubulin and remain stably constricted. If hexylene glycol is removed, alpha-tubulin staining disappears from the polar lobe constriction, which relaxes, whereas microtubules remain in the cleavage furrow, which remains constricted. These observations suggest that asymmetric distribution of microtubules affects early Ilyanassa cleavage patterns, and that continued presence of microtubules extending through an intercellular bridge is important for stabilization of the bridge constriction prior to completion of cytokinesis. These data provide the basis for further analysis of the role of microtubules in possible microgravity disruptions of Ilyanassa development.

Animals↗

PubMed1976

Correlative assay of computerized cranial tomography CCT, water content and specific gravity in normal and pathological postmortem brain.

An assay of water content and specific gravity in normal and pathological autopsy brain has been correlated with CCT attenuation values obtained just prior to brain cutting. Formalin fixation does not alter normal values so that fixed brain appears to be suitable for this type of study. Low attenuation values in CCT correlate better with changes in specific gravity, rather than water in infarcts, but they have a close relationship to water content in edema. The high water content in infarcts of the white matter reveals a striking disparity in fluid control between cortex and white matter, which has not been emphasized in experimental studies. Water movement within and around blood clots has been discussed.

Body Water↗

PubMed1983

Quantitative histochemistry of rat lumbar vertebrae following spaceflight.

Spaceflight has been shown to cause alterations in bone mineral content, bone growth, and resorption. In this study, the effects of return to gravity immediately and 6 and 29 days following spaceflight on bone of rat vertebral bodies were histochemically analyzed. Immediately postflight, there was no significant change in calcium salt content of the vertebrae, but 6 days later it was significantly decreased (P less than 0.05). By 29 days postflight, the calcium salt content had returned to normal. Postflight collagen content was not significantly altered. Keratosulfate was significantly higher (P less than 0.05) in trabecular bone of rats immediately postflight and 6 days postflight. Chondroitin sulfate was increased in vertebral bone on days 6 and 29 postflight. The histochemical patterns observed in this study suggest that bone turnover slows in vertebrae during spaceflight allowing bone ageing. The results support the contention that a form of osteolysis begins, immediately upon return to gravity, to remove components of old bone at which time mineral levels do decrease and levels of chondroitin and keratosulfates shift. The osteolysis phase is quickly followed by new bone replacement which is completed before 29 days postspaceflight.

Animals↗

PubMed1982

Body position and esophageal sphincter pressure in infants.

Lower esophageal sphincter pressure was measured in infants in the supine, prone, right lateral, left lateral, and upright positions; 14 had gastroesophageal reflux and 16 did not. Position had no significant effect on pressure in either group. However, patients with reflux had significantly lower pressures in each position. The rationale for postural therapy in infants with reflux cannot be based on alterations in sphincter pressure but is more likely related to the effect of gravity on the gastric pool. Compared with roentgenograms of the upper gastrointestinal tract or esophageal manometry the one- and 24-hour pH probe tests best identified reflux in those patients who were first seen with symptoms compatible with this diagnosis.

Esophagogastric Junction↗

PubMed2004

The effect of the orientation of the noncircular radial head on elbow kinematics.

OBJECTIVE: The objective of this study was to identify the effect of radial head shape and orientation on elbow kinematics in the otherwise intact elbow. DESIGN: Biomechanical study, analyzing simulated active motion of cadaveric arms. BACKGROUND: A discrepancy exists between the noncircular anatomy of the radial head and radial head prostheses. The effect of radial head shape is unknown. METHODS: Kinematic effects of radial head shape were tested in six fresh-frozen upper extremities. A custom-made native radial head prosthesis was used to simulate altered shape conditions, by rotating the radial head 90 degrees. Three-dimensional spatial orientation of the ulna was recorded, during simulated active motion. A three factor ANOVA was used to compare (a) nominal and 90 degrees oriented conditions, (b) throughout the flexion arc (c) in three forearm positions (P < 0.05). Post-hoc Tukey tests were done to assess significance. RESULTS: No significant effect of altering radial head shape was found on total ulnohumeral laxity and angulation during gravity valgus stress. We did find a significant effect on total ulnar axial rotation and rotation during gravity valgus stress. CONCLUSION: The outer shape of the radial head seems to change rotation of the ulna during flexion-extension in an otherwise intact elbow. RELEVANCE: The shape of the radial head effects intact elbow kinematics. Clinical importance of this finding is clear. If a sub-optimally placed radial head prosthesis were to be used in an otherwise intact elbow, the elbow could be at risk for early ulnohumeral arthritis.

Biomechanical Phenomena↗

PubMed2004

Using isotope tracers to study metabolism: application in mouse models.

The application of isotope tracers for investigating metabolism in mice is discussed. To familiarize the reader, some basic principles regarding the use of tracer methods are outlined. Emphasis is placed on showing how investigators are using isotope tracers to study the regulation of carbohydrate, fat and/or protein turnover in vivo. Finally, some of the advantages of using labeled water (i.e., 2H(2)O and/or H(2)18O) to trace the kinetics of biological processes are considered. The background provided in this report should assist engineers in designing studies that enhance our understanding of conditions in which metabolism is altered (e.g., diabetes, cancer cachexia, failure to thrive and travel at zero-gravity).

Animals↗

PubMed2004

[Vibration risk during neonatal transport].

AIM: The aim of this paper is to assess the entity of the mechanical vibrations which newborn and medical staff are exposed to and to evaluate the possible risks connected with excessive exposure. METHODS: Vibrations during a simulated emergency ambulance transport were studied. Vibration values with an accelerometer at the level of the incubator's mattress and at passengers' and pilot's seat level were measured. Mean accelerations (awz) and peak accelerations (awpeak), measured using a ponderation filter, according with ISO standard 2631, were considered. RESULTS: Inside the incubator an acceleration mean value of 1.33 (+/-0.13) m/s(2) and peak values of 11.8 (+/-0.1) m/s(2) were found. On passengers' seats the awz findings were 0.55 m/s(2) (+/-0.13) and 0.56 m/s(2) (+/-0.08) while awpeak respectively 4.8 m/s(2) (+/-0.1) and 10.2 m/s(2) (+/-0.1). On pilot's seat a mean acceleration of 0.48 m/s(2) (+/-0.08) and an awpeak value of 4.5 m/s(2) (+/-0.1) were found. CONCLUSION: Peak vibration values which newborns are exposed to (11.8 m/s(2)) are high, when compared with acceleration of gravity (9.8 m/s(2)); this can provoke repeated jerks. Environmental stress can easily alter the stability of an ill newborn and interfere with care manoeuvres. Decreasing vibrations in neonatal transport unit could increase the safety of newborns, reducing the risks which newborns are actually exposed to.

Humans↗

PubMed1977

[Clinical and echo-phonomechanocardiographic study of the mitral valve prolapse (author's transl)].

The results of a study of 32 patients with the clinical and auscultatory suspect of M.V.P., confirmed echo-cardiographically, are reported. Part of the pathogenetic cause of the symptomatology and ECgraphic alterations are attributed to the hypomagnesiemia. The relation between exercise test positivity and gravity of the symptomatology is confirmed. The phonomechanocardiographic tracings were studied and the morphological features from C.P. and apexcardiogram are described and shown, with particular attention given to the clicks and systolic murmurs. The authors describe three types of prolapse, early, "U"-and "double U"--shaped pansystolic, and, relating echo-to-phonomechanocardiographic results, point out features which seem typical of the M.V.P. Echo-phono mechanocardiography is confirmed as a technique which is useful and sufficiently safe and reliable in diagnosing, detecting and following the disease in its not yet perfectly acknowledged evolution. It avoids the use of invasive tools which could become extremely dangerous.

Adult↗

PubMed1999

Is skeletal muscle ready for long-term spaceflight and return to gravity?

It is now clear that prevention of muscle debilitation during spaceflight will require a broader approach than simple exercise aimed at strengthening of the muscle fibers. The levels of several hormones and receptors are altered by unloading and must be returned to homeostasis. Pharmacotherapy and gene transfer strategies to raise the relative level of structural proteins may minimize the problems faced by astronauts in readapting to Earth-gravity. Up to now, we have only minimally exploited microgravity for advancing our understanding of muscle biology. A research laboratory in the space station with a centrifuge facility (gravity control) is essential for conducting basic research in this field. Microgravity has proven an excellent tool for noninvasively perturbing the synthesis of muscle proteins in the search for molecular signals and gene regulatory factors influencing differentiation, growth, maintenance and atrophy of muscle. Understanding the relation between blood flow and interstitial edema and between workload and subsequent structural failure are but two important problems that require serious attention. The roles of hormones and growth factors in regulating gene expression and their microgravity-induced altered production are other urgent issues to pursue. These types of studies will yield information that advances basic knowledge of muscle biology and offers insights into countermeasure design. This knowledge is likely to assist rehabilitation of diseased or injured muscles in humans on Earth, especially individuals in the more vulnerable aging population and persons participating in strenuous sports. Will the skeletal muscle system be prepared for the increased exposure to microgravity and the return to gravity loading without injury when space station is operational? The answer depends in large part on continued access to space and funding of ground-based models and flight experiments. The previous two decades of spaceflight research have described the effects of microgravity on multiple systems. The next generation of experiments promises to be even more exciting as we are challenged to define the cellular and molecular mechanisms of microgravity-induced changes.

Animals↗

PubMed1983

The state of gravity sensors and peculiarities of plant growth during different gravitational loads.

In the primary roots of lettuce shoots grown under altered gravitational conditions--180 degrees inversion on the centrifuged clinostat, horizontal clinostat and in dynamic weightlessness--localization of the cellular organelles, cell morphology and peculiarities of growth have been studied. Significant changes took place in the localization of amyloplasts on the horizontal clinostat. The changes of amyloplast position in the cap cells on the horizontal clinostat and under weightlessness are similar. A change of the normal shoot position (180 degrees inversion and horizontal clinostat) causes an inhibition of growth. Weightlessness increases the length of axial organs and cells in the zone of elongation, but decreases the nitotic index in comparison to the centrifuged control. The anlysis of the formation of generative organs has been carried out for Arabidopsis plants grown on board the orbital station Salyut-6. The ability of plants to undergo vegetative growth and to pass through early phases of generative development under weightlessness was confirmed.

Arabidopsis↗

PubMed2003

Hyper-gravity effects on the Arabidopsis transcriptome.

Callus cultures of Arabidopsis thaliana (cv. Columbia) in Petri dishes were exposed to altered g-forces by centrifugation (1-10 g). Using semi-quantitative RT-PCR transcripts of genes coding for metabolic key enzymes (ADP-glucose pyrophosphorylase, ADPG-PP; beta-amylase, fructose-1,6-bisphosphatase, FBPase; glyceraldehyde-P dehydrogenase, GAPDH; hydroxymethylglutaryl-CoA reductase, HMG; phenylalanine-ammonium-lyase, PAL; PEP carboxylase, PEPC) were used to monitor threshold conditions for g-number (all) and time of exposure (beta-amylase) which led to altered amounts of the gene product. Exposure to approximately 5 g and higher for 1 h resulted in altered transcript levels: transcripts of beta-amylase, PAL, and PEPC were increased, those of ADPG-PP decreased, while those of FBPase, GAPDH, and HMG were not affected. This probably indicates a shift from starch synthesis to starch degradation and increased rates of anaplerosis (PEPC: supply of ketoacids for amino acid synthesis). In order to get more information about g-related effects on gene expression, we used a 1-h exposure to 7 g for a microarray analysis, using a commercial A. thaliana chip with 4105 unique annotated clusters/genes (IncyteGenomics). Transcripts of more than 200 genes were significantly increased in amount (ratio 7 g/1 g control; 2(1.6) and larger). They fall into several categories. Transcripts coding for enzymes of major pathways form the largest group (25%), followed by gene products involved in cellular organization and cell wall formation/rearrangement (17%), signalling, phosphorylation/dephosphorylation (12%), proteolysis and transport (10% each), hormone synthesis plus related events (8%), defense (4%), stress-response (2%), and gravi-sensing (2%). Many of the alterations are part of a general stress response, but some changes related to the synthesis/rearrangement of cell wall components could be more hyper-g-specific. We only found few gene products, which were decreased in relation to 1 g controls, and these were less significant (ratio < 2(1.6)). We thus assume that g-forces above a threshold of about 5 g for 1 h are sensed by plant cells in general, causing distinct metabolic responses, which obviously in part, are regulated by gene expression.

Arabidopsis↗

PubMed1999

Hemodynamic and metabolic alterations associated with intravenous infusion of a combination of adenosine triphosphate and magnesium chloride in conscious horses.

OBJECTIVE: To determine hemodynamic and metabolic effects of IV infusion of ATP-MgCl2 combination and maximal safe IV infusion rate in conscious horses. ANIMALS: 6 adult female horses. PROCEDURE: All horses received an IV infusion of ATP-MgCl2 combination, beginning at a rate of 0.05 mg of ATP/kg of body weight/min, which was increased by 0.05 mg/kg/min increments at 10-minute intervals until a rate of 1.0 mg/kg/min was achieved. Data were collected prior to the start of the infusion, at the end of each infusion rate, and at 15-minute intervals for the next hour after discontinuation of the infusion. Measured or calculated hemodynamic variables included cardiac output, cardiac index, heart rate, stroke volume, systemic and pulmonary arterial pressures, and systemic and pulmonary vascular resistances. Arterial blood gas tensions, CBC, plasma biochemical profiles, urine volume and specific gravity, and selected clinical signs of disease also were evaluated. RESULTS: Intravenous infusion of ATP-MgCl2 significantly increased cardiac output, decreased systemic vascular resistance, and caused mild pulmonary hypertension. Magnitude of the hemodynamic alterations was dependent on rate of infusion. Maximal safe infusion rate for these horses was 0.3 mg/kg/min. All horses became lethargic, and their appetites diminished during the infusion; 5 horses had mild signs of abdominal discomfort. Flank sweating was observed in all horses as infusion rate increased. Urine volume and specific gravity and hematologic, biochemical, and arterial blood gas alterations were detected during and after infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Intravenous administration of ATP-MgCl2 in healthy, conscious, adult horses caused various metabolic and hemodynamic alterations that were without appreciable detrimental effects.

Adenosine Triphosphate↗

PubMed2001

Effect of gravity change on the production of thrombopoietic growth factors.

It is reported that the stay in the space develops anemia, thrombocytopenia, and altered function and structure of red blood cell. The mechanism of these abnormalities was not clarified yet. The cloning of the thrombopoietin (TPO), followed by the analysis of TPO and c-mpl (its cellular receptor) knockout mice confirmed its role as the primary regulator of thrombopoiesis. TPO has been shown to stimulate both megakaryocyte colony growth from marrow progenitor cells and the maturation of immature megakaryocyte to form functional platelet. This process includes the massive cytoskeletal rearrangement, such as proplatelet formation and fragmentation of proplatelet. In this study we have focused on the production of thrombopoietic growth factors in mice those were exposed to gravity change by parabolic flight (PF).

Animals↗