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In the pigeon vestibular responses from threshold to saturation will be compared in laboratory and in a satellite zero gravity. It is expected that following the Weber-Flechner law sensitivity in zero gravity conditions will be much higher. The experiment in orbit and the necessary equipment are described.
Dissolved oxygen (DO) concentrations were during 2 months continuously measured in an intercepting sewer. Measurements were made upstream and downstream in a 3.6 km gravity sewer. DO showed significant diurnal variations mainly caused by changes in the organic matter composition of the wastewater. At low temperatures the gravity sewer was strictly aerobic. However, towards the end of the measuring campaign, DO concentrations decreased as temperature increased and the sewer became anaerobic part of the day. A conceptual model that takes into account bulk water and biofilm DO uptake as well as reaeration was used to simulate the DO measured. Using measurements from the upstream station as input, the model was calibrated to yield good validation results of the DO at the downstream station.
The paper is dedicated to the memory of Galileo Galilei whose work is a great contribution to the development of a new branch of science--gravitation biology. Penetration of man into outer space necessitates a study of the role of gravity in the onto- and phylogenetic development of living organisms. This allows one to get insight into the biological action of weightlessness under the conditions of long-term space flight. The paper summarizes some results of the investigation of weightlessness effects in experiments on animals and during flights of Soviet and American astronauts. The rearing of animals in a special centrifuge under the conditions of prolonged action of accelerations simulating an increased gravity affects noticeably the formation of vegetative (height, weight, metabolism) and animal (vestibulo-tonic reflexes) functions as well as reactivity of the organism. Experiments employing the rearing of animals in a centrifuge represent one of the most promising methods of studying the urgent problem--biological action of increased and decreased gravitation conditions.
Effects of gravity on linear blood velocity in jugular, femoral and popliteal veins were examined in 45 healthy male and female subjects. The zero-g effects were simulated by putting the subjects in the recumbent position, and the gravity effects were provoked by active orthostasis. Blood velocity was measured with CW Doppler (4 MHz). No difference was determined in velocity of the blood flow along the veins in recumbent subjects. In the head-up position, blood flow was significantly increased in the jugular vein and decreased in the leg veins. In several instances, brief contraction of the crus muscles caused a noticeable rise in the peak velocity along the femoral vein. In the head-up position this hemodynamic effect of the crus pump was much more pronounced.
We have recently demonstrated that a transcription factor, nuclear factor kappa B (NF-kappa B), plays a key role in the production of cytokine and cell adhesion molecules in osteoblastic cells. In the present study, we investigated the effects of vector-averaged gravity (clinostat rotation) on tumor necrosis factor (TNF)-alpha-induced activation of NF-kappa B in human osteoblastic HOS-TE85 cells. After a 72-hr clinostat culture, the cells were treated with TNF-alpha for 30 min. Electrophoretic mobility shift assay using the nuclear extracts revealed that the DNA-binding activity of NF-kappa B was substantially reduced in clinostat-cultured cells compared with the stationary control. Concomitantly, the transactivation of NF-kappa B was examined by a transfection study. The cells were transfected with a plasmid expressing a luciferase reporter gene driven by multimerized NF-kappa B sites. They were cultured in the clinostat for 48-hr, followed by a 4-hr treatment with TNF-alpha. Clinostat culture resulted in a significant decrease in the luciferase activities, being consistent with the decreased binding of NF-kappa B. These results indicate that exposure of HOS-TE85 cells to vector-averaged gravity impairs NF-kappa B activation by TNF-alpha.
When free flow electrophoresis (FFE) is applied to the separation and purification process under microgravity, higher separability is expected than that under usual 1 G environment, because sedimentation of samples and heat convection can be neglected. Although FFE under micro-gravity is a very important technique for efficient separation of macromolecules because of the above merits, FFE unit (FFEU) should be more sophisticated to give stable operation, high separability, high through-put and high separation efficiency. In this study, fundamental research to achieve FFE with such high performance was done by using a commercial FFEU. The research contains (1) the quantitative study on the separation mode of FFE and separation efficiency, (2) the feasibility analysis of free-flow bidirectional isotachophoresis (FFBITP) which enables separation of cations anions simultaneously by isotachophoresis (ITP) and zone electrophoresis (ZE), (3) the optimization of hardware factors such as thickness of the separation chamber which may cause deterioration of separation due to heat convection, and (4) the analysis of hardware factors depending on the long-time operation. The ultimate goal of this study is to obtain fundamental data for the development of FFE for the international space station. In this paper, the experimental results obtained in a reduced-gravity aircraft was mainly.
The study of the effect of gravity on blood volumes in the main cervical arteries was conducted with voluntary participation of 50 normal men and women. Blood volumes were determined with the ultrasound technique. The circulatory effect of gravity was simulated by administration of the active standing test. Circulating volumes in the common carotid, internal carotid and vertebral arteries in the supine position were 464, 342 and 110 ml/min, respectively and decreased significantly up to 352, 262 and 84 ml/min, respectively in the standing position. The orthostatic reduction in the volume of blood circulating along the vertebral artery was proportional to that in the internal carotid artery. Specific contribution of changes in vascular capacity to the blood volume reduction was shown to be predominant.
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. Therefore, it is necessary to elucidate the mechanism of the effect of the gravity change on the thrombocytopoiesis, which plays the important role for the hemostasis, using animal models. The cloning of 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 thrombopoiesis in mice those were exposed to gravity change by parabolic flight (PF).
It is well known that exposure to various stresses leads to pain suppression in animals. However, there is no report about the effects of gravitational alteration to serve as a kind of stress. The purpose of the present study is to clarify the effect of hypergravity (2 G) on the nociceptive responses and histochemical changes in rats. We examined the level of the threshold of withdrawal reflex against the noxious [correction of noxicious] stimulation in rats that were exposed to 2 G. Data show that the 2 G exposure elevates the nociceptive threshold. We have demonstrated for the first time that gravity change induces analgesic effects on rats in concomitant with c-fos induction in the arcuate, and paraventricular nuclei of rat hypothalamus. Gravity change acts as a kind of stress in rats.
DNA double strand break (DSB) causes many cytotoxic effects such as cellular lethality, somatic mutation, and carcinogenesis. Fidelity of DSB repair is a important factor that determines the quality of genomic stability. It is known that the most of DSBs are properly repaired on the earth, however, little is known whether those are rejoined at the same fidelity even under the space environment. One of the DSB repair pathway, homologous recombination (HR), allows the cells to repair their DSBs with error free. Therefore, the efficiency of HR is a good index to assess the fidelity of DSB repair. In order to clarify the effect of gravity stress on HR pathway, we established a cell line that can detect a site-specific DNA repair via HR. The cells carrying a reporter construct for HR were incubated under hypergravity condition after induction of site specific DSB. Our preliminary results suggest that the gravity stress may affect the HR efficiency.
Based on experience in microgravity and on centrifuge induced hypergravity, exposure to either altered force field causes marked effects in animals and humans. It would seem logical that changes from unit gravity would have different effects depending on whether gravity is increased or decreased. Examples will be presented of responses to altered gravitational fields and changes in human and animal musculoskeletal, cardiopulmonary neurovestibular and metabolic responses.
The objective of this study was to measure the forces applied on an object manipulated in different gravitational fields attained during parabolic flights. Eight subjects participated flights (ES) and four were inexperienced (NES). They had to move continuously an instrumented object up and down in three different gravitational conditions (1 g, 1.8 g, 0 g). In 1 g, the grip force precisely anticipated the fluctuations of load force which was maximum and minimum at the bottom and at the top of the arm trajectory respectively. When the gravity changed (0 g and 1.8 g), the grip-load force coupling persisted for all the subjects from the first parabola. While the ES immediately exerted a grip force appropriate to the gravity, the NES dramatically increased their grip when faced with hyper and microgravity for the first time. Then, they progressively released their grip until a continuous grip-load force relationship with regard to 1 g was established after the fifth parabola. We suggest that each new gravitational field is rapidly incorporated into an internal model within the CNS which can then be reused as required by the occasion.
During the early embryonic development of the amphibian, several events are presumed to be dependent on the ground gravity (egg rotation of equilibrium, formation of the grey crescent, symmetrization, cleavage). Will development occur normally in the absence of the gravity? The experience FERTILE had led to obtain in weightlessness, onboard the space station Mir, the natural fertilization and the embryonic development of the salamander Pleurodeles waltl, an amphibian urodele. All the embryos developed in microgravity acquired normal bilateral symmetry. The egg rotation that occurs on earth after fertilization is clearly not necessary in urodeles to determine the position of symmetrical plan. The results obtained in P. waltl are in accordance with those observed earlier in the anuran Xenopus laevis and the fish Oryzias latipes.
UNLABELLED: The aim of this study was trying to create a new instrument able to evaluate the final gravity prognostic of acute pancreatitis, taking note that none of used scores has proved to have a complete efficiency in such kind of appreciations. METHOD: The study has been made on 437 patients treated in the Surgical Clinic of St Pantelimon Hospital between 1996-2000. There have been analyzed all clinical, biochemical, imagistic and operative elements and there were selected those semnificatively correlated with the results. RESULTS: We obtained a four-degree classification of potential gravity of the disease in aim to know how aggressive the therapy should be, even in delusive forms of the disease. CONCLUSIONS: We so propose to analyze this new classification that offered us to our patient's results able to reduce mortality.
Responses of Hoffman (H)-reflex in human soleus to changes in the levels of gravity, activities of skeletal muscles, and/or fluid distribution of lower limbs during the parabolic flight of a jet airplane and/or using a tilting table were studied. The time interval between the electrical stimulation and the appearance of either M- or H-wave and the amplitude of M-wave were not influenced by the changes in gravity and fluid distribution levels. However, the H-wave amplitude was increased when the subjects were exposed to microgravity (microgravity-G). Hypergravity at 1.5- or 2-G had no effect on the H-wave amplitude. The H-reflex had no relation with the changes of electromyogram activities of skeletal muscles and fluid volume in lower limbs. Further, the H-wave amplitude was even decreased insignificantly when the distribution of lower limb fluid was reduced at head-down position on the table. It is suggested that an acute exposure to microgravity-G increases the excitability of soleus motor pool, but the mechanism is still unclear.
Biological and chemical systems in which the pattern of flow of energy and matter imposes self-organization can be seen as examples of excitable media. One property of such media is the presence of excitation waves. The Belouzov-Zabotinsky(B-Z) reaction system and the retinal spreading depression wave are examples of experimental models of excitable media in which the influence of gravity can be studied. In this paper we describe one especial module constructed to test the influence of gravity in gels of the B-Z system. In the gel condition, convection effects are minimized. The results will be directly comparable to retinal experiments programmed by the same group and complete a series of investigations of systematic comparison of the modulation of chemical and biological excitation waves by weak external forces.
Among the universal environmental factors changes of the gravity flow are not enough investigated. Relations between the dog corticoadrenal and thyroid glands functional rhythms and the properties of curvature level surfaces of the gravity flow changes were established. The suggested mechanism of the effect of gravitation flow changes includes ability of cells and ultrastructures to reflect the geometric properties of the local space.
A clinical randomized study was conducted to compare 28 closed polyurethane (PU) drainage systems and 28 open polyvinylchloride (PVC) (Redon) drainage systems. The aim was to find whether the Redon drains could be replaced by PU drains without suction in the field of joint and soft tissue surgery. In another study, 27 PU gravity-drainage systems were implanted for surface electron microscopy. There was no difference in the volume of fluid drained. The tendency to diversion of the secretion induced by a thrombus in the drain was significantly lower in the PU drainage group than in the PVC-Redon group. Extraction of the drain was significantly less painful in the PU group than in the group with Redon drains. No complications occurred in either group. The surface electron-microscope study revealed slight adherence of thrombotic material to the inner wall of the drain in the PU group only. The thrombi were mobile and had a smooth surface, so that they could not block the drainage of secretions. In our opinion, PU gravity-drainage systems could be substituted for PVC-Redon drainage systems in the field of traumatology. This would exclude the potential toxic effects of PVC.