Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SPACE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources
PubMed2005

Countermeasure for space flight effects on immune system: nutritional nucleotides.

Microgravity and its environment have adverse effects on the immune system. Abnormal immune responses observed in microgravity may pose serious consequences, especially for the recent directions of NASA for long-term space missions to Moon, Mars and deep Space exploration. The study of space flight immunology is limited due to relative inaccessibility, difficulty of performing experiments in space, and inadequate provisions in this area in the United States and Russian space programs (Taylor 1993). Microgravity and stress experienced during space flights results in immune system aberration (Taylor 1993). In ground-based mouse models for some of the microgravity effects on the human body, hindlimb unloading (HU) has been reported to cause abnormal cell proliferation and cytokine production (Armstrong et al., 1993, Chapes et al. 1993). In this report, we document that a nutritional nucleotide supplementation as studied in ground-based microgravity analogs, has potential to serve as a countermeasure for the immune dysfunction observed in space travel.

Animals↗
PubMed1991

Imaging of the parapharyngeal space: anatomy and pathology.

A multitude of histologic neoplasms occur within the boundaries of the parapharyngeal space. Contrast enhanced computed tomography and recently MRI have greatly enhanced the preoperative diagnosis of parapharyngeal space tumors. MRI is currently the modality of choice in evaluating masses originating in the parapharyngeal space or masses from adjacent spaces which grow into the parapharyngeal space. Gadolinium DTPA enhanced MRI of head and neck tumors is helpful for demonstrating neoplastic involvement of paranasal sinus, perineural tumor extension, or intracranial extension of neoplasms. Parapharyngeal space tumors are equally demonstrated by unenhanced MRI. The majority of tumors involving the parapharyngeal space are from the deep portion of the parotid gland or from minor salivary glands, and the majority of these tumors are benign mixed tumors. Based on the CT appearance and enhancement characteristics, it is difficult to accurately distinguish a minor salivary gland tumor from a neurogenic tumor. MR tissue signal characteristics alone cannot be reliably utilized in making this distinction. Internal carotid artery displacement remains the most reliable distinguishing feature. Minor salivary gland tumors will displace the internal carotid artery posterior and lateral, whereas neurogenic tumors will displace the internal carotid artery anterior and medial.

Branchioma↗
PubMed1985

Birth spacing and fertility limitation: a behavioral analysis of a nineteenth century frontier population.

Our analysis of changing birth interval distributions over the course of a fertility transition from natural to controlled fertility has examined three closely related propositions. First, within both natural fertility populations (identified at the aggregate level) and cohorts following the onset of fertility limitation, we hypothesized that substantial groups of women with long birth intervals across the individually specified childbearing careers could be identified. That is, even during periods when fertility behavior at the aggregate level is consistent with a natural fertility regime, birth intervals at all parities are inversely related to completed family size. Our tabular analysis enables us to conclude that birth spacing patterns are parity dependent; there is stability in CEB-parity specific mean and birth interval variance over the entire transition. Our evidence does not suggest that the early group of women limiting and spacing births was marked by infecundity. Secondly, the transition appears to be associated with an increasingly larger proportion of women shifting to the same spacing schedules associated with smaller families in earlier cohorts. Thirdly, variations in birth spacing by age of marriage indicate that changes in birth intervals over time are at least indirectly associated with age of marriage, indicating an additional compositional effect. The evidence we have presented on spacing behavior does not negate the argument that parity-dependent stopping behavior was a powerful factor in the fertility transition. Our data also provide evidence of attempts to truncate childbearing. Specifically, the smaller the completed family size, the longer the ultimate birth interval; and ultimate birth intervals increase across cohorts controlling CEB and parity. But spacing appears to represent an additional strategy of fertility limitation. Thus, it may be necessary to distinguish spacing and stopping behavior if one wishes to clarify behavioral patterns within a population (Edlefsen, 1981; Friedlander et al., 1980; Rodriguez and Hobcraft, 1980). Because fertility transition theories imply increased attempts to limit family sizes, it is important to examine differential behavior within subgroups achieving different family sizes. It is this level of analysis which we have attempted to achieve in utilizing parity-specific birth intervals controlled by children ever born.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

Effect of migration, distribution and spacing of pig embryos on pregnancy and fetal survival.

Pig embryos enter the uterus from the oviduct about 48 h after ovulation at about the 4-cell stage. They remain near the tip of the uterine horn until about Day 6 when they migrate towards the body of the uterus. By Day 9 some embryos have entered the horn opposite the one of origin and continue migrating until Day 12. At Day 12 embryos can no longer successfully move to a different site. The critical signal for recognition of pregnancy occurs at Day 12 at the same time that embryos are elongating at a rapid rate. The distribution of embryos throughout the length of the horns has occurred by this time and spacing accompanied by uterine growth takes place. The speed of migration is not influenced by the number of embryos but may be affected by secretions from the embryos acting on the uterus. A significant section of unoccupied uterus at Day 12 will prevent continuance of pregnancy regardless of the number of embryos present in the occupied section. When the number of embryos is so few as to not occupy the uterus fully, pregnancy will not continue. Removal of embryos from a significant section of the uterus after Day 14 does not stop an existing pregnancy. Embryos are spaced nearly equidistant from each other with the absolute space between fetuses dependent on the total uterine space available. The position of the fetus in the uterus affects the spacing between fetuses; fetuses at the tip of the horn before Day 25 have the greatest space with the space decreasing from the tip to the body.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Identification of cells lining pseudovascular spaces of benign pigmented nevi.

So-called pseudovascular spaces, said to occur in 10% of benign pigmented nevi, are presumed to be shrinkage artifacts of tissue processing. In an attempt to characterize the cells lining these spaces, three benign pigmented nevi were studied with immunoperoxidase techniques. It was found that they stained positively with an anti-melanoma antibody, P97a (gamma-2a), but negatively with an antibody against an antigen-related factor VIII, which is a marker for vascular endothelium. We conclude that these spaces are lined by melanocytes of nevi and that the spaces are not truly vascular. In one specimen, the spaces were filled with erythrocytes, which suggest that the spaces were present before fixation. It has been suggested, though, that altered collagen and elastic tissue and the nevi themselves may diminish the resistance of the dermis to the mechanical stress of the biopsy procedure, which results in the formation of these spaces.

Antibodies, Neoplasm↗
PubMed1982

Auditory and visual maps of space in the optic tectum of the owl.

The receptive field properties and functional organization of visual and auditory responses were studied in the optic tectum of the barn owl (Tyto alba). Most units throughout the depth of the tectum responded to both visual and auditory stimuli. The entire visual field of each eye was represented topographically in the contralateral tectum. In the portion of the tectal map representing the zone of binocular vision, 50% of the superficial layer units and 100% of the deep; layer units were driven binocularly. The representation of the frontal binocular region of space was greatly expanded in the map; the average magnification factor was 3 times greater for the frontal binocular zone than for the monocular zone. The responses of the superficial and deep tectal units to auditory stimuli were space specific; they responded only when a sound source was located in a particular region of space, or receptive field, regardless of the intensity or type of sound used. Most auditory receptive fields contained a distinct "best area" where a sound source was most effective in driving the unit. Auditory space, as defined by receptive fields and best areas, was represented topographically in the tectum. The auditory and visual maps of space had the same orientations, positions, magnification factors, and termination coordinates at the anterior and dorsal edges of the tectum. Yet the maps lost their registry near the posterior and ventral margins where the most peripheral regions of space were represented. These characteristics suggest that the spatiotopic organization in the tectum is a compromise between a tendency for the space representations of different modalities to align and for the representation of each modality to fill the entire tectum.

Acoustic Stimulation↗
PubMedDate not supplied

Optimal spacing of right ventricular bipolar catheter electrodes for detecting cardiac pumping by an automatic implantable defibrillator.

Our defibrillation-detecting system uses both ECG and right ventricular impedance change (delta Z). We studied the effect of catheter electrode spacing on delta Z in 10 dogs with body weights of 10 to ,5 kg and heart weights of 67 to 220 g. Impedance to 20-kHz 100--muA square waves was measured between two 1-cm-long electrodes mounted on a No. 12F catheter and wedged into the right ventricular apex. Catheters with spacings of 5 to 25 mm between the electrodes were tested during sinus rhyhm and ventricular fibrillation. During sinus rhythm the mean beat-to-beat delta Z was 23 +/- 4 omega using the 5-mm spacing. Wider spacing gave smaller, and hence less desirable, delta Z. Some delta Z signals were recorded during ventricular fibrillation, and 5-mm spacing was more sensitive to these than wider spacing. This resulted in some prolongation of the time between onset of fibrillation and application of the defibrillation shock, but should decrease false positive diagnosis of fibrillation. No clear relationship was observed between delta Z and body weight or heart weight. We conclude that the 5-mm spacing is best for detection of pumping by the catheter-impedance method in hearts of this weight range.

Animals↗
PubMed1994

[Dorsal gliding and functional spaces of the metacarpophalangeal transition].

Although the relevance of capillary and gliding spaces of the back of the hand and the finger located dorsal to the extensor aponeurosis in the metacarpo-phalangeal region between the layers of the subdermal connective tissue is often emphasized clinically in inflammatory and acute traumatic occurrences, hardly any information has been published concerning the morphology of these spaces. By means of plastic-injection techniques, varying configurations of capillary spaces in the distal region of the dorsum manus of cadavers were found. The deep connective tissue spaces located dorsal to the extensor aponeurosis were shown to have proximal connections to the dorsal tendon sheaths of the carpus, whereas superficial gliding spaces tended to vary in their expanse depending on the subcutaneous and epifascial septa. The deep as well as the superficial capillary gliding spaces are adapted as mobilizing and limiting structures for the movements of the metacarpo-phalangeal joints and the various mechanical stresses of the skin of the back of the hand. A high degree of exactness in the reconstruction of the marginal elements of such functional spaces appears to be of special importance with regard to a total restoration of the functional capability of the metacarpo-phalangeal joint region.

Capillaries↗
PubMed1993

[CT and MR imaging anatomy of the fascia in the pelvic extraperitoneal space].

CT and MRI anatomy of the fascia in the pelvic extraperitoneal space has not been established. CT and some MR imagings of nine patients who received irradiation to the pelvis and of eleven patients who received transarterial infusion for urinary bladder carcinoma were studied about the anterior and posterior attachment sites of the coccygeus muscle, the sacrouterine ligament and the lateral ligament. Observing the course of the inferior gluteal artery, the author set up three axial levels; (a), (b) and (c) levels, where the artery passes in front of the piriformis muscle, just gets over the coccygeus muscle and over the sacrospinous ligament, respectively. At (b) and (c) levels, the posterior attachment site of the sacrouterine ligament was the coccygeus muscle and the posterior attachment site of the lateral ligament was the sacrouterine ligament. By these ligaments, the pelvic extraperitoneal space was divided into three compartments; the prevesical, the perivesical and the perirectal spaces. The prevesical space was limited by the coccygeus muscle and the sacrouterine ligament posteriorly, the perivesical space was limited by the sacrouterine ligament and the lateral ligament posteriorly, and the perirectal space was surrounded by the sacrouterine ligament and the coccygeus muscle. On the coronal image through the level slightly posterior to the anus, the sacrouterine ligament attached to the levator ani muscle at a lateral third like a screen. On the basis of these results, new axial and coronal models of the pelvis extraperitoneal space are presented, which are useful for understanding the location and spread of the lesion.

Adult↗
PubMed1997

Orbital venous drainage into the anterior cavernous sinus space: microanatomic relationships.

OBJECTIVE: Microsurgical anatomy and relationships in the region of the superior orbital fissure and anterior part of the cavernous sinus were studied, with special attention to the venous structures. METHODS: Microanatomic dissections were performed in 24 specimens from human cadavers, fixed in formalin, with the aid of a microdrill and operating microscope. RESULTS: A protocol of dissection was developed, enabling plane-by-plane exposure of the cranial nerves passing from the cavernous sinus to the superior orbital fissure and farther, on disclosure of the junction between the ophthalmic veins and the anterior cavernous sinus space. The main draining vessel was the superior ophthalmic vein. The inferior ophthalmic vein was much thinner and it was identified in 91.7% of cases. These two vessels fused together to form a common venous confluence approximately 5 mm in length that entered the anterior cavernous sinus space in its anterior or anteroinferior aspect. The shape of this venous drain varied greatly, from that of a typical vein to that of a venous lake. The latter was characterized by a relatively narrow opening into the anterior cavernous sinus space and lacunar widening of the vessel in its central part. No case of a separate entrance of the superior and inferior ophthalmic veins into the anterior cavernous sinus space was encountered. The anterior cavernous sinus space was described as a slit-like venous chamber located in front of the anterior genu of the intracavernous segment of the internal carotid artery. The anteroposterior diameter of this space was 3.2 +/- 0.4 mm; it was filled with blood, and no venous structures inside this space were observed. CONCLUSION: The knowledge of the anatomic details described may be useful for elaborating surgical approaches to this region and for planning the treatment of carotid-cavernous fistulas.

Carotid Artery, Internal↗
PubMed1996

Fundamental study on the size and inter-key spacing of numeric keys for touch screen.

The purpose of this study was to reveal the optimum size and inter-key spacing of numeric square keys for touch screens. Six male students (22-25 years old) and three female students (21-24 years old) volunteered as subjects for this experiment. Each subject took part in data entry tasks using numeric square keys of touch devices. The sizes of keys were 6, 12, 21, 30 and 39 mm and each the inter-key spacing was 0, 3, 6, 12 and 21 mm. Response times with key sizes of 6 and 12 mm were significantly slower than with key sizes of 21 and 30 mm (p < 0.001). Furthermore, the key size of 6 mm significantly caused more errors than the key sizes of 12, 21, 30 and 39 mm (p < 0.05). The response time with inter-key spacing of 3 mm was significantly faster than with that of 0, 6, 12 and 21 mm (p < 0.001). Inter-key spacing of 0 mm significantly produced more errors than other inter-key spacing. Subjective ratings for inter-key spacing of 3, 6 and 12 mm were significantly better than those of 0 and 21 mm (p < 0.05). These results suggested that the optimum size of numeric square keys for touch screens should be more than 21 mm and optimum inter-key spacing should be from 3 to 6 mm. Optimum key size, however, must be selected with regard to the limitation of screen size.

Adult↗
PubMed1998

The re-emergence of space medicine as a distinct discipline.

Space Medicine is a discipline whose scope will encompass primary and advanced medical care amidst the environmental constraints of space. At one time, there was a Department of Space Medicine associated with the U.S. Air Force School of Aviation Medicine. Until 1993, an academic, university-based training program dedicated to space medicine did not exist. This paper reviews the history of space medicine in the United States. It presents the current conceptions of space medicine, and postulates the need for space medicine to mature as a distinct discipline.

Aerospace Medicine↗
PubMed1998

Deep subfascial space infections.

Infections of the deep subfascial spaces of the hand and wrist are relatively uncommon but well recognized. Potential sites for infection include the interdigital web space, dorsal subaponeurotic space, Parona's space, thenar space, midpalmar space, and hypothenar space. Treatment involves surgical drainage in combination with appropriate systemic antibiotics. Several alternative surgical approaches have been described. Selection is based on the extent and precise location of the infection and surgeon preference. Aggressive hand therapy usually is required in the postoperative period to avoid the complication of tendon adhesions, joint contractures, and hand stiffness. With early recognition and expedient surgical treatment, a satisfactory outcome can be expected for those infections that occur in otherwise healthy, nonimmunocompromised patients.

Drainage↗
PubMed1990

Medical considerations for extending human presence in space.

The prospects for extending the length of time that humans can safely remain in space depend partly on resolution of a number of medical issues. Physiologic effects of weightlessness that may affect health during flight include loss of body fluid, functional alterations in the cardiovascular system, loss of red blood cells and bone mineral, compromised immune system function, and neurosensory disturbances. Some of the physiologic adaptations to weightlessness contribute to difficulties with readaptation to Earth's gravity. These include cardiovascular deconditioning and loss of body fluids and electrolytes; red blood cell mass; muscle mass, strength, and endurance; and bone mineral. Potentially harmful factors in space flight that are not related to weightlessness include radiation, altered circadian rhythms and rest/work cycles, and the closed, isolated environment of the spacecraft. There is no evidence that space flight has long-term effects on humans, except that bone mass lost during flight may not be replaced, and radiation damage is cumulative. However, the number of people who have spent several months or longer in space is still small. Only carefully-planned experiments in space preceded by thorough ground-based studies can provide the information needed to increase the amount of time humans can safely spend in space.

Adaptation, Physiological↗
PubMed1992

Space habitat contaminant growth models.

This paper outlines the need for and role of Contaminant Growth Models (CGM) in designing space habitats and space mission operations. The tremendous complexity of the contamination problem and the current lack of data suggests that a "layered" approach to CGM development and utilization be made in conjunction with medical/toxicological research and risk assessments. Two space habitat contaminant examples: thermodegradation and hydrazine, are utilized to show how such a model might be useful in analyzing the environment of a space habitat. The examples also depict how NASA's interdisciplinary Center for Space Environmental Health (CSEH) will combine medical/toxicological research results with engineering environmental system design tools to set standards and help in the design, prediction, monitoring and safe control of space habitats. Since the CSEH project is just beginning, the contents of the paper are descriptive of the goal and the approach being taken, rather than conclusive in nature.

Ammonia↗
PubMed1995

The experience in operation and improving the Orlan-type space suits.

Nowadays significant experience has been gained in Russia concerning extravehicular activity (EVA) with cosmonauts wearing a semi-rigid space suit of the "Orlan" type. The conditions for the cosmonauts' vital activities, the operational and ergonomic features of the space suit and its reliability are the most critical factors defining the efficiency of the scheduled operation to be performed by the astronaut and his safety. As the missions performed by the cosmonauts during EVA become more and more elaborate, the requirements for EVA space suits and their systems become more and more demanding, resulting in their consistent advancement. This paper provides certain results of the space suit's operation and analysis of its major problems as applied to the Salyut and MIR orbiting stations. The modification steps of the space suit in the course of operation (Orlan-D, Orlan-DM, Orlan-DMA) and its specific features are presented. The concept of the suited cosmonauts' safety is described as well as trends for future space suit improvements.

Equipment Design↗
PubMed1992

Commercial involvement in the development of space-based plant growing technology.

Considerable technological progress has been made in the development of controlled environment facilities for plant growth. Although not all of the technology used for terrestrial facilities is applicable to space-based plant growth facilities, the information resident in the commercial organizations that market these facilities can provide a significant resource for the development of the plant growing component of a CELSS. In 1985, NASA initiated an effort termed the Centers for the Commercial Development of Space (CCDS). This program endeavors to develop cooperative research and technology development programs with industrial companies that capitalize on the strengths of industry-university working relationships. One of the these CCDSs, the Wisconsin Center for Space Automation and Robotics (WCSAR), deals with developing automated plant growth facilities for space, in cooperation with several industrial partners. Concepts have been developed with industrial partners for the irradiation, water and nutrient delivery, nutrient composition control and automation and robotics subsystems of plant growing units. Space flight experiments are planned for validation of the concepts in a space environment.

Equipment Design↗
PubMed1994

Cellular changes in microgravity and the design of space radiation experiments.

Cell metabolism, secretion and cell-cell interactions can be altered during space flight. Early radiobiology experiments have demonstrated synergistic effects of radiation and microgravity as indicated by increased mutagenesis, increased chromosome aberrations, inhibited development, and retarded growth. Microgravity-induced changes in immune cell functions include reduced blastogenesis and cell-mediated, delayed-type hypersensitivity responses, increased cytokine secretions, but inhibited cytotoxic effects and macrophage differentiation. These effects are important because of the high radiosensitivity of immune cells. It is difficult to compare ground studies with space radiation biology experiments because of the complexity of the space radiation environment, types of radiation damage and repair mechanisms. Altered intracellular functions and molecular mechanisms must be considered in the design and interpretation of space radiation experiments. Critical steps in radiocarcinogenesis could be affected. New cell systems and hardware are needed to determine the biological effectiveness of the low dose rate, isotropic, multispectral space radiation and the potential usefulness of radioprotectants during space flight.

Animals↗