bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distance of Cecum Ligated Influences Mortality, Tumor Necrosis Factor-Alpha and Interleukin-6 Expression following Cecal Ligation and Puncture in the Rat
Authors: Singleton K.D. , Wischmeyer P.E. 
Published: October 2003

<i>Background/Aim:</i> A mainstay of laboratory research into new therapies for sepsis has been the cecal ligation and puncture (CLP) model in rodents. Previous data indicate that the number of punctures made in the cecum and needle size utilized are primary determinants of mortality. Despite this, variability exists in mortality from this model, even when needle size is held constant. The aim of the present study was to evaluate the influence of the length of cecum ligated, independent of needle size, as a determinant of mortality. <i>Materials and Methods:</i> We evaluated this by ligating various cecal lengths in male Sprague-Dawley rats. A double puncture was then made with a 20-gauge needle, and mortality was analyzed. Plasma TNF-α and IL-6 expression was assessed at 6 h. Animals received no antibiotics, were not fasted, and fluid resuscitation was administered. <i>Results:</i> We determined that mortality does not begin to occur until a distance of >5% of cecal length is ligated. Further, our findings indicate that in this model, 90–100% mortality occurs 4 days following CLP when a distance of >30% is ligated. TNF-α and IL-6 expression is markedly increased with increasing length of cecum ligated. <i>Conclusions:</i> Our data demonstrate that the length of cecum ligated is a major determinant of mortality in the CLP model of sepsis. These findings indicate that investigators must rigorously control the distance of the cecum ligated in order to generate consistent mortality and inflammation data when utilizing the CLP model in rats. Further, the mortality from this model can be adjusted to fit the individual needs of a particular experiment.
Altered Cardiovascular Responses to Nitrosorbide in Alcohol Withdrawal
Authors: Kähkönen Seppo , Zvartau Edwin E. 
Published: October 2003

The cardiovascular effects and pharmacokinetics of a single dose (20 mg sublingually) of isosorbide dinitrate (ISDN) were studied in 9 alcohol-dependent men during alcohol withdrawal syndrome (AW) on day 1 and after the resolution of AW on day 10. At the onset of AW, ISDN and its metabolites caused a hypotensive effect, which was increased on day 10, while no differences in ISDN-induced decrease in stroke volume were observed. Tachycardiac response to ISDN was more pronounced at onset of AW. On day 10, the AUC<sub>0–1.5 h</sub>, C<sub>max</sub> and t<sub>½</sub> of ISDN were increased compared with day 1. The results of this study suggest that nitric oxide may modulate the cardiovascular system in AW.
LPS-Induced Changes in Myocardial Markers in Neonatal Rats
Authors: Ravindranath Thyyar M. , Goto Masakatsu , Bakr Soliman , Ramasamy Ravi 
Published: October 2003

Lipopolysaccharide (LPS) produces varied systemic metabolic effects. We studied the effects of LPS on the cardiac fatty acid profile and its relationship to energy metabolism and inflammatory mediators that included TNF-α and nitric oxide synthase (NOS) in 10-day-old neonatal rat pups. Rat pups received an i.p. injection of LPS after a 4-hour starvation period, followed by collection of blood and cardiac tissue 4 h following LPS administration. Compared to controls, LPS induced significant hypoglycemia and hyperlactacidemia, suggesting the development of endotoxic shock. The result was a significant depression in total fatty acid levels as well as non-esterified fatty acid in the cardiac tissue of the LPS-treated pups. In addition, LPS-treated pups also showed a significant increase in TNF-α, NOS levels with a depressed redox state and energy metabolism in cardiac tissue. These observations suggest that endotoxic shock in 10-day-old rat pups induces a systemic inflammatory response with a depression in fatty acid metabolism that may contribute to myocardial failure.
Current status of lung transplantation
Authors: Lau C.L. , Patterson G.A. 
Published: October 2003

Two decades have passed since the first successful clinical lung transplant was performed in 1983, and, in the interim, lung transplantation has become the preferred treatment option for a variety of end-stage pulmonary diseases. Remarkable progress has been made in the field through refinement of technique and improved understanding of transplant immunology and microbiology.Unfortunately, donor shortages continue to limit the more widespread application of lung transplantation. In order to address this issue, marginal donors, living lobar and split lung donor techniques, and nonheartbeating donors have been used clinically to increase the number of donor lungs available.Chronic rejection of the lung allograft is currently the major hurdle limiting long-term survival. To date, prevention of known risk factors and treatment strategies have not lessened the devastating toll this process has on lung transplant survival. Better understanding of the cause of chronic rejection is needed in order to develop novel strategies for its treatment. Promotion of immune tolerance is a promising area that could potentially eliminate chronic rejection.The present article discusses recent advances in lung transplantation. It also details the major issues facing the field today. Only through continued clinical and experimental investigation will lung transplantation eventually reach its full potential.
Respiratory failure
Authors: Roussos C. , Koutsoukou A. 
Published: October 2003

Respiratory failure occurs due mainly either to lung failure resulting in hypoxaemia or pump failure resulting in alveolar hypoventilation and hypercapnia. Hypercapnic respiratory failure may be the result of mechanical defects, central nervous system depression, imbalance of energy demands and supplies and/or adaptation of central controllers.Hypercapnic respiratory failure may occur either acutely, insidiously or acutely upon chronic carbon dioxide retention. In all these conditions, pathophysiologically, the common denominator is reduced alveolar ventilation for a given carbon dioxide production.Acute hypercapnic respiratory failure is usually caused by defects in the central nervous system, impairment of neuromuscular transmission, mechanical defect of the ribcage and fatigue of the respiratory muscles.The pathophysiological mechanisms responsible for chronic carbon dioxide retention are not yet clear. The most attractive hypothesis for this disorder is the theory of “natural wisdom”. Patients facing a load have two options, either to push hard in order to maintain normal arterial carbon dioxide and oxygen tensions at the cost of eventually becoming fatigued and exhausted or to breathe at a lower minute ventilation, avoiding dyspnoea, fatigue and exhaustion but at the expense of reduced alveolar ventilation. Based on most recent work, the favoured hypothesis is that a threshold inspiratory load may exist, which, when exceeded, results in injury to the muscles and, consequently, an adaptive response is elicited to prevent and/or reduce this damage. This consists of cytokine production, which, in turn, modulates the respiratory controllers, either directly through the blood or probably the small afferents orviathe hypothalamic-pituitary-adrenal axis. Modulation of the pattern of breathing, however, ultimately results in alveolar hypoventilation and carbon dioxide retention.
Development of a damping seat slide to reduce whiplash injury
Authors: Schmitt K-U , Muser M , Heggendorn M , Niederer P , Walz F 
Published: October 2003

To prevent whiplash injury, a new seat slide was developed. In the case of a rear-end impact, the device allows the vehicle seat to slide backwards while damping this motion. Deformable steel profiles serve as damping elements. To activate the device, a trigger system is used which detects an acceleration threshold. Sled test experiments were performed to analyse the behaviour of the new system. The tests were conducted to mimic rear-end collisions with a delta-V of 16 km/h. A BioRID dummy was used as a human surrogate. The results indicate the beneficial influence of the damping seat slide on the occupant kinematics. In particular, the so-called S-shape deformation of the neck assessed by the neck injury criterion (NIC) is reduced. Comparing a standard car seat with and without the damping seat slide, it was shown that the NIC is reduced by approximately 40 per cent. Hence it was shown that besides the head restraint and the recliner that are used in other whiplash protection systems, the seat slide has the potential to prevent whiplash injury.
Artificial Gravity
Authors: Young Laurence R. 
Published: October 2003

AbstractArtificial gravity (AG) is not gravity at all. It is not a field force or a “force at a distance.” Neither does its strength obey the inverse square law of attraction that determines the orbital motion of planets. However, in terms of its action on any mass, it is indistinguishable from “real gravity.” Instead of gravitational pull, it exerts a centrifugal force, proportional to the mass that is being accelerated centripetally in a rotating device. Although the effect of AG on an extended body differs from that of true gravity, the effects on any given mass are equivalent. Thus AG is simply the imposition of acceleration on a body to recover the forces that are eliminated by the free fall of orbital flight. Probably the most serious health threat to humans during interplanetary flight comes from radiation exposure en route and on some extraterrestrial surface. Beyond that, prolonged exposure to weightlessness itself can result in deconditioning many of the body's systems. For space voyages of several years, such as those envisioned for exploration of Mars, the human requires some sort of “countermeasure” to reduce or eliminate this deconditioning.The notion of creating a substitute for gravity through centrifugation was introduced early in the conception of human space travel. The popularization of AG, however, is attributable to the science fiction community. Only two space missions early in the program were devoted to animal studies. Human in‐flight results were anecdotal.The envelope of operation for AG is limited by several factors. The “comfort zone” for AG with a rotational radius of up to 1000 feet is bounded by several constraints. Theminimum gravitational level, normally measured at the rim of a centrifuge, is the key parameter in the design space. Themaximum gravitational acceleration levelis also a factor if short‐radius intermittent AG is used.Themaximum angular velocityof the AG device is limited by the Coriolis forces encountered when walking or when moving objects, and by the motion sickness and disorientation experienced with certain kinds of head movements. Coriolis accelerations are real inertial accelerations that occur when moving within a rotating framework. The choice of AG design depends on whether continuous or intermitent AG is to be used. These choices are discussed.
Astronomy‐Infrared
Authors: Werner Michael , Harwit Martin 
Published: October 2003

Abstract
This article describes the astrophysical questions that can be addressed at infrared wavelengths, the advantages of pursuing infrared astronomy from space, the enabling technologies, and the missions that have been flown and are planned to exploit the unique potential of this wavelength range. The infrared band covers three decades—from ∼1 μm to ∼1000 μm—that encompass a very wide range of instrumental techniques and scientific issues. Discussion here has been limited to rocket‐ and satellite‐borne missions aimed primarily at astrophysical targets and have omitted the infrared instruments that have been carried on planetary probes. The short‐wavelength limit of the detailed discussion is drawn at 2.5 μm but note that the Near Infrared Camera and Multi‐Object Spectrograph (NICMOS) instrument on the Hubble Space Telescope (HST) have operated very successfully in the 1 to 2.5‐μm band; these wavelengths are also among those studied by the Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer (COBE). Wavelengths longer than ∼200 μm have been probed extensively from space only by the highly successful COBE spacecraft. COBE observations of the nearby Universe are discussed but we cannot do justice to its extraordinary spatial and spectral measurements of the cosmologically critical cosmic microwave background radiation (CMBR).
An introductory section describes the astrophysical uniqueness of the infrared and the tremendous benefits to be gained by carrying infrared instrumentation above the atmosphere. Next three key technical areas of particular importance for infrared astronomy—detectors, cryogenics, and optics—and the way they have been adapted to the space environment are presented. Next, comes a review of previous and near‐term missions for infrared astronomy from space, emphasizing the evolution of both science and technology since the first rocket experiments of the 1960s. The final mission discussed in detail is the Space Infrared Telescope Facility (SIRTF), which was scheduled for launch in 2003. SIRTF's advanced technology and great scientific potential will mark the end of the first phase of exploration of the Universe in the infrared band. But SIRTF is also a beginning, because it sets the stage for the missions of the next decade. Finally, a summary of the technological challenges and scientific opportunities of these upcoming programs are given.
Optical Astrometry from Space
Authors: Kovalevsky Jean 
Published: October 2003

AbstractAstrometry plays a very particular part in the realm of astronomy. One can define astrometry as the part of astronomy that measures the apparent positions of celestial bodies on the sky. And, because these positions vary with time, the objective is to describe and study these motions that, for stars, provide two essential parameters: the proper motion and the parallax from which the distance is derived. As an extension, one ascribes also to astrometry the measurement of apparent dimensions and shapes of celestial bodies. However, in this article, the determination of star positions, the primary goal of space astrometry is considered.The physical quantities that are measured by astrometry are angles that are often very small. Radians are not used in astrometry; the basic units are degrees and seconds of arc (denoted″). Smaller units are necessary, and astrometrists are currently using milliseconds of arc and now are starting to use one millionth part of a second of arc. Some basics that have to be known for further understanding are given.Before describing what space has brought to astrometry and what it is expected to bring in the future, it is necessary, for comparison, to present the achievements of ground‐based astrometric observations. One must distinguish two classes of instruments that differ by the area of the sky measured. Descriptions of the instrument are mentioned in space missions have been launched: Hipparcos and facilities on the Hubble Space Telescope. These are described.The successful entry of astrometry among space astronomical techniques is a powerful incentive to devise and propose to space agencies new more powerful, more effective space astrometric missions with a better science return to cost ratio. Many projects have been presented during the last decade. Some have already been thoroughly studied, and engineered descriptions of a possible realization exist. The two most ambitious projects are described. However, they have not yet been built, so the information given here is provisional. Other projects will only be mentioned, even if some might be launched before those more sophisticated.
Biological Responses and Adaptation to Spaceflight: Living in Space—An International Enterprise
Authors: Nicogossian Arnauld 
Published: October 2003

AbstractAttempting to predict human responses to space travel, physicians and researchers of the 1950s speculated that microgravity and spaceflight itself would present significant challenges‐if not barriers—to the human body. They hypothesized that the combined stresses of launch acceleration, weightlessness, radiation, and heavy deceleration upon reentry would be incapacitating. At the very least, they predicted that the bodily systems sensitive to gravity‐based cues would function improperly or not at all. Given this grim forecast, the initial focus was to demonstrate that life, away from Earth, could survive space travel and subsequent return to Earth's gravity. Faced with this challenge, both the United States and Soviet Union turned first to ground simulations, such as immobilization studies, and then to the study of animal test subjects launched on board high‐altitude balloons, suborbital, and orbital rockets. What followed is a series of biological satellites that carried a variety of living specimens, from isolated cell cultures to whole instrumented organisms. The Soviet Union relied primarily on canines to provide such data, whereas the United States chose primates for such experimentation.This article attempt to present a concise overview of life in space, physiological responses to this new environment, and associated health implications for future space travelers. Consideration must be given to the hostile, and yet dynamic environment of space; to the craft that protects the crew members from the harsh environment, allowing them to navigate in space; and to life itself as it adjusts to this novel environment. Today it is known that some adaptive changes, such as immune and hormonal responses, are primarily the response to the stresses of confinement, isolation, and spacecraft design, not necessarily to the unique effects of the space environment.
Comets
Authors: Cochran Anita L. 
Published: October 2003

Abstract
Comets are small icy/dusty bodies left over from the formation of the solar system and represent the least altered bodies from the epoch of formation. They formed in the outer parts of our planetary system; some still reside in their primordial reservoir known as the Kuiper belt; those formed in the Uranus‐Neptune region were ejected to a spherical reservoir known as the Oort cloud; those formed near Jupiter and Saturn were ejected from our solar system entirely.
The nuclei of comets are small (typically a few km) bodies composed of ices and dust. Of the ices 80% is water ice. The dust is composed of organics and silicates. As the nucleus is heated, the ices sublime and flow outward from the nucleus. The dust/gas mixture forms a large coma and even larger tails.

To date, several spacecraft have visited comets and have made measurements
in situ
, but we have yet to retrieve samples and return them for study in laboratories. The vast majority of our knowledge of cometary composition comes, however, from remote observations obtained with ground‐based or Earth‐orbital telescopes. These data are gathered using spectroscopic and photometric techniques on a wide variety of comets. The spectrum of a comet is characterized predominantly by molecular emission coupled with an underlying continuum of sunlight reflecting from the dust.

Every single day, about 100 tons of interplanetary material hits the upper atmosphere of Earth, and some of that material reaches the surface. A large percentage of the smallest particles originates in comets as dust grains that are released when ices sublime. These small cometary particles represent no hazard to Earth. Many of them are fluffy aggregates that “float” in the upper stratosphere for long periods of time and are occasionally collected for study by specially equipped high‐flying aircraft.
Much can be learned about the nature of comets via observations from the ground and Earth orbit. However, one can never see the nucleus of the comet in this way, and information is inferred about its nature by using models. To study the nuclei of comets, it is necessary to send spacecraft to them. These spacecraft missions can range from simple flybys, to rendezvous missions, to landings and sample returns. The completed and planned cometary missions of the U.S. and other nations are described.
Earth Orbiting Satellite Theory
Authors: Steven Nerem R. 
Published: October 2003

AbstractThe objective of this article is to provide an introduction to the theory of satellite orbital motion. Although the discussion focuses on Earth‐orbiting satellites, the theory is equally valid for computations around other primary bodies including the Moon, the Sun, and the planets. The majority of the discussion focuses on the problem of two bodies. The solution provides sufficient accuracy for many problems in astrodynamics. Perturbations from the two‐body problem are discussed because a number of applications require greater accuracy. The solution of these more complex problems is generally accomplished using numerical integration techniques, which is beyond the scope of this chapter.
Immunology and Infection in Space
Authors: Shearer William T. , Sonnenfeld Gerald 
Published: October 2003

AbstractThis article on alterations of immune responses in space travel is intended to provide a review of the background and rationale for the hypothesis that immune function of humans on long‐term space flight missions will be sufficiently altered that immune compromise occurs, thus rendering astronauts subject to opportunistic infections, particularly activation of latent viruses and the development of malignancies. The article reviews published information on the evidence of immune compromise in humans and animals flown in space and in human and animal earth‐bound models of spaceflight. These alterations in immune function are discussed in the context of model secondary immunodeficiency states where external forces predispose humans to repetitive infection, debilitation, and cancer. An attempt will be made to quantitate the degree of immune impairment observed in space travelers and earth‐bound equivalent model subjects and to predict what the astronauts on the Mars Mission might experience in terms of the occurrence of reactivated viral infections and the development of malignancy. Because this article includes many technical terms that may not be familiar to the reader, a glossary of immunological terms is included.
Mercury
Authors: Nelson Robert M. 
Published: October 2003

AbstractMercury, our solar system's innermost planet, is shrouded in mystery, despite the fact that it is Earth's third closest planetary neighbor and is one of the five planets known to the ancients. It is fairly easy to see. It appears to an Earth‐based observer at approximately 2‐month intervals as a bright object visible to the naked eye near the Sun, shortly before sunrise or after sunset. However, despite its nearness and its brightness, it ranks only behind the most distant planet, Pluto, in our understanding of its interior structure, its surface composition, and the dynamic interactions between its surface, its tenuous atmosphere, and its magnetosphere. These topics are subjects of this article. The physical processes that have governed Mercury's origin and evolution are poorly understood. The planet has many unusual qualities, including an unexpected magnetic field and a remarkably high density (mass to volume ratio). It has even been suggested that water ice may be present just under the surface at some places on the planet, even though its surface is the closest to the Sun of all of the planets. Because Mercury is close to the Sun, the response of the planet's environment to solar activity is also expected to be greatest of all of the planets.Mercury has the most extreme daily temperature fluctuation of all of the planets. Understanding more about Mercury is important for testing models of planetary formation, and the results of these research activities will have great impact on models of the origin and evolution of the solar system. Obstacles to exploration of mercury conclude the discussion.