Showing papers by "University of Texas at Austin published in 1997"
TL;DR: In this article, the authors showed that a reversible loss in capacity with increasing current density appears to be associated with a diffusion-limited transfer of lithium across the two-phase interface.
Abstract: Reversible extraction of lithium from LiFePO 4 (triphylite) and insertion of lithium into FePO 4 at 3.5 V vs. lithium at 0.05 mA/cm 2 shows this material to be an excellent candidate for the cathode of a low-power, rechargeable lithium battery that is inexpensive, nontoxic, and environmentally benign. Electrochemical extraction was limited to ∼0.6 Li/formula unit; but even with this restriction the specific capacity is 100 to 110 mAh/g. Complete extraction of lithium was performed chemically; it gave a new phase, FePO 4 , isostructural with heterosite, Fe 0.65 Mn 0.35 PO 4 . The FePO 4 framework of the ordered olivine LiFePO 4 is retained with minor displacive adjustments. Nevertheless the insertion/extraction reaction proceeds via a two-phase process, and a reversible loss in capacity with increasing current density appears to be associated with a diffusion-limited transfer of lithium across the two-phase interface. Electrochemical extraction of lithium from isostructural LiMPO 4 (M = Mn, Co, or Ni) with an LiClO 4 electrolyte was not possible; but successful extraction of lithium from LiFe 1-x Mn x PO 4 was accomplished with maximum oxidation of the Mn 3+ /Mn 2+ occurring at x = 0.5. The Fe 3+ /Fe 2+ couple was oxidized first at 3.5 V followed by oxidation of the Mn 3+ /Mn 2+ couple at 4.1 V vs. lithium. The Fe 3+ -O-Mn 2+ interactions appear to destabilize the Mn 2+ level and stabilize the Fe 2+ level so as to make the Mn 3+ /Mn 2+ energy accessible.
6,945 citations
TL;DR: In this paper, it was shown that the membrane states required by the supersymmetric matrix quantum mechanics are contained as excitations of the matrix model, which is a non-perturbative realization of the holographic principle.
Abstract: We suggest and motivate a precise equivalence between uncompactified 11-dimensional $M$ theory and the $N=\ensuremath{\infty}$ limit of the supersymmetric matrix quantum mechanics describing $D0$ branes. The evidence for the conjecture consists of several correspondences between the two theories. As a consequence of supersymmetry the simple matrix model is rich enough to describe the properties of the entire Fock space of massless well separated particles of the supergravity theory. In one particular kinematic situation the leading large distance interaction of these particles is exactly described by supergravity. The model appears to be a nonperturbative realization of the holographic principle. The membrane states required by $M$ theory are contained as excitations of the matrix model. The membrane world volume is a noncommutative geometry embedded in a noncommutative spacetime.
3,345 citations
TL;DR: In this article, a new finite element method is presented that features the ability to include in the finite element space knowledge about the partial differential equation being solved, which can therefore be more efficient than the usual finite element methods.
Abstract: A new finite element method is presented that features the ability to include in the finite element space knowledge about the partial differential equation being solved This new method can therefore be more efficient than the usual finite element methods An additional feature of the partition-of-unity method is that finite element spaces of any desired regularity can be constructed very easily This paper includes a convergence proof of this method and illustrates its efficiency by an application to the Helmholtz equation for high wave numbers The basic estimates for a posteriori error estimation for this new method are also proved © 1997 by John Wiley & Sons, Ltd
2,387 citations
TL;DR: Mgp, a mineral-binding ECM protein3 synthesized by vascular smooth-muscle cells and chondrocytes, is the first inhibitor of calcification of arteries and cartilage to be characterized in vivo.
Abstract: Calcification of the extracellular matrix (ECM) can be physiological or pathological. Physiological calcification occurs in bone when the soft ECM is converted into a rigid material capable of sustaining mechanical force; pathological calcification can occur in arteries and cartilage and other soft tissues. No molecular determinant regulating ECM calcification has yet been identified. A candidate molecule is matrix GLA protein (Mgp), a mineral-binding ECM protein synthesized by vascular smooth-muscle cells and chondrocytes, two cell types that produce an uncalcified ECM. Mice that lack Mgp develop to term but die within two months as a result of arterial calcification which leads to blood-vessel rupture. Chondrocytes that elaborate a typical cartilage matrix can be seen in the affected arteries. Mgp-deficient mice additionally exhibit inappropriate calcification of various cartilages, including the growth plate, which eventually leads to short stature, osteopenia and fractures. These results indicate that ECM calcification must be actively inhibited in soft tissues. To our knowledge, Mgp is the first inhibitor of calcification of arteries and cartilage to be characterized in vivo.
2,030 citations
TL;DR: Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) has been used to generate ion images of samples in one or more mass-to-charge (m/z) values, providing the capability of mapping specific molecules to two-dimensional coordinates of the original sample.
Abstract: Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) has been used to generate ion images of samples in one or more mass-to-charge (m/z) values, providing the capability of mapping specific molecules to two-dimensional coordinates of the original sample. The high sensitivity of the technique (low-femtomole to attomole levels for proteins and peptides) allows the study of organized biochemical processes occurring in, for example, mammalian tissue sections. The mass spectrometer is used to determine the molecular weights of the molecules in the surface layers of the tissue. Molecules desorbed from the sample typically are singly protonated, giving an ion at (M + H)+, where M is the molecular mass. The procedure involves coating the tissue section, or a blotted imprint of the section, with a thin layer of energy-absorbing matrix and then analyzing the sample to produce an ordered array of mass spectra, each containing nominal m/z values typically covering a range of over 50 000 Da. Images...
1,952 citations
16 Jun 1997
TL;DR: The paper gives an overview of the various tasks involved in motion analysis of the human body, and focuses on three major areas related to interpreting human motion: motion analysis involving human body parts, tracking of human motion using single or multiple cameras, and recognizing human activities from image sequences.
Abstract: Human motion analysis is receiving increasing attention from computer vision researchers. This interest is motivated by a wide spectrum of applications, such as athletic performance analysis, surveillance, man-machine interfaces, content-based image storage and retrieval, and video conferencing. The paper gives an overview of the various tasks involved in motion analysis of the human body. The authors focus on three major areas related to interpreting human motion: 1) motion analysis involving human body parts, 2) tracking of human motion using single or multiple cameras, and 3) recognizing human activities from image sequences. Motion analysis of human body parts involves the low-level segmentation of the human body into segments connected by joints, and recovers the 3D structure of the human body using its 2D projections over a sequence of images. Tracking human motion using a single or multiple camera focuses on higher-level processing, in which moving humans are tracked without identifying specific parts of the body structure. After successfully matching the moving human image from one frame to another in image sequences, understanding the human movements or activities comes naturally, which leads to a discussion of recognizing human activities. The review is illustrated by examples.
1,665 citations
TL;DR: In this article, the authors provide a framework for understanding possible impacts of the Internet on marketing to consumers by analyzing channel intermediary functions that can be performed on the Internet, suggesting classification schemes that clarify the potential impact of the internet across different products and services, positioning the Internet against conventional retailing channels, and identifying similarities and differences that exist between them.
Abstract: Past commentaries on the potential impact of the Internet on consumer marketing have typically failed to acknowledge that consumer markets are heterogeneous and complex and that the Internet is but one possible distribution, transaction, and communication channel in a world dominated by conventional retailing channels This failure has led to excessively broad predictions regarding the effect of the Internet on the structure and performance of product and service markets The objective of this article is to provide a framework for understanding possible impacts of the Internet on marketing to consumers This is done by analyzing channel intermediary functions that can be performed on the Internet, suggesting classification schemes that clarify the potential impact of the Internet across different products and services, positioning the Internet against conventional retailing channels, and identifying similarities and differences that exist between them The article concludes with a series of questions designed to stimulate the development of theory and strategy in the context of Internet-based marketing
1,461 citations
TL;DR: In this article, the authors provide a framework for the development of accessibility measures and two case studies suggestive of the range of possible approaches are presented, as well as issues that planners must address in developing an accessibility measure.
Abstract: Accessibility is an important characteristic of metropolitan areas and is often reflected in transportation and land-use planning goals. But the concept of accessibility has rarely been translated into performance measures by which policies are evaluated, despite a substantial literature on the concept. This paper is an attempt to bridge the gap between the academic literature and the practical application of such measures and provide a framework for the development of accessibility measures. Issues that planners must address in developing an accessibility measure are outlined, and two case studies suggestive of the range of possible approaches are presented.
1,437 citations
TL;DR: In this article, the authors focus on the transport and transformations of land-derived organic matter in the ocean, highlighting recent research on the patterns and processes involved in the degradation of terrestrial organic matter.
1,335 citations
TL;DR: This analysis provides global distributions for fine root biomass, length, and surface area with depth in the soil, and global estimates of nutrient pools in fine roots.
Abstract: Global biogeochemical models have improved dramatically in the last decade in their representation of the biosphere. Although leaf area data are an important input to such models and are readily available globally, global root distributions for modeling water and nutrient uptake and carbon cycling have not been available. This analysis provides global distributions for fine root biomass, length, and surface area with depth in the soil, and global estimates of nutrient pools in fine roots. Calculated root surface area is almost always greater than leaf area, more than an order of magnitude so in grasslands. The average C:N:P ratio in living fine roots is 450:11:1, and global fine root carbon is more than 5% of all carbon contained in the atmosphere. Assuming conservatively that fine roots turn over once per year, they represent 33% of global annual net primary productivity.
1,309 citations
TL;DR: In this paper, the authors examined the factors that affect the likelihood of voluntary and forced turnover of chief executive officers and found that poor CEOs are easier to identify and less costly to replace in industries that consist of similar firms than in heterogeneous industries.
TL;DR: In this paper, the authors examined the increase in relative wages for skilled workers in Mexico during the 1980s and found that growth in FDI was positively correlated with the relative demand for skilled labor.
Journal Article•
TL;DR: The authors compare various hierarchical mixture prior formulations of variable selection uncertainty in normal linear regression models, including the nonconjugate SSVS formulation of George and McCulloch (1993), as well as conjugate formulations which allow for analytical simplification.
Abstract: This paper describes and compares various hierarchical mixture prior formulations of variable selection uncertainty in normal linear regression models. These include the nonconjugate SSVS formulation of George and McCulloch (1993), as well as conjugate formulations which allow for analytical simplification. Hyperpa- rameter settings which base selection on practical significance, and the implications of using mixtures with point priors are discussed. Computational methods for pos- terior evaluation and exploration are considered. Rapid updating methods are seen to provide feasible methods for exhaustive evaluation using Gray Code sequencing in moderately sized problems, and fast Markov Chain Monte Carlo exploration in large problems. Estimation of normalization constants is seen to provide improved posterior estimates of individual model probabilities and the total visited probabil- ity. Various procedures are illustrated on simulated sample problems and on a real problem concerning the construction of financial index tracking portfolios.
TL;DR: The authors examined whether spillovers associated with one firm's export activity reduce the cost of exporting for other firms, identifying two sources of spillovers: export production in general and the specific activities of multinationals.
TL;DR: This work studies the process using simple models that track both demography and the evolution of a quantitative trait in a population that is continuously distributed in space to dramatically shift the balance between gene flow and local adaptation, allowing a species with a limited range to suddenly expand to fill all the available habitat.
Abstract: Gene flow from the center of a species' range can stymie adaptation at the periphery and prevent the range from expanding outward. We study this process using simple models that track both demography and the evolution of a quantitative trait in a population that is continuously distributed in space. Stabilizing selection acts on the trait and favors an optimum phenotype that changes linearly across the habitat. One of three outcomes is possible: the species will become extinct, expand to fill all of the available habitat, or be confined to a limited range in which it is sufficiently adapted to allow population growth. When the environment changes rapidly in space, increased migration inhibits local adaptation and so decreases the species' total population size. Gene flow can cause enough maladaptation that the peripheral half of a species' range acts as a demographic sink. The trait's genetic variance has little effect on species persistence or the size of the range when gene flow is sufficiently...
TL;DR: The need for future research examining gender differences in ADHD is strongly indicated, with attention to methodological limitations of the current literature, including the potential confounding effects of referral bias, comorbidity, developmental patterns, diagnostic procedures, and rater source.
Abstract: Objective To quantitatively review and critically evaluate literature examining gender differences in attention-deficit hyperactivity disorder (ADHD). Method A meta-analysis of relevant research based on 18 studies meeting inclusion criteria was performed. Domains evaluated included primary symptomatology, intellectual and academic functioning, comorbid behavior problems, social behavior, and family variables. Results Gender differences were not found in impulsivity, academic performance, social functioning, fine motor skills, parental education, or parental depression. However, compared with ADHD boys, ADHD girls displayed greater intellectual impairment, lower levels of hyperactivity, and lower rates of other externalizing behaviors; it was not possible to evaluate the extent to which referral bias affected these findings. Some gender differences were clearly mediated by the effects of referral source; among children with ADHD identified from nonreferred populations, girls with ADHD displayed lower levels of inattention, internalizing behavior, and peer aggression than boys with ADHD, while girls and boys with ADHD identified from clinic-referred samples displayed similar levels of impairment on these variables. Conclusions The need for future research examining gender differences in ADHD is strongly indicated, with attention to methodological limitations of the current literature, including the potential confounding effects of referral bias, comorbidity, developmental patterns, diagnostic procedures, and rater source.
TL;DR: In this article, the role of structure on the position of the octahedral redox couple in compounds having the same polyanions, four iron phosphates:, and were investigated.
Abstract: To understand the role of structure on the position of the octahedral redox couple in compounds having the same polyanions, four iron phosphates: , and were investigated. They vary in structure as well as in the manner in which the octahedral iron atoms are linked to each other. The redox couple in the above compounds lies at 2.8, 2.9, 3.1, and 3.5 eV, respectively, below the Fermi level of lithium. The reason for the difference in the position of the redox couples is related to changes in the P‒O bond lengths as well as to changes in the crystalline electric field at the iron sites.
TL;DR: In this paper, the authors examine possible causative relations between tectonics and environmental and biologic changes during the Neoproterozoic and Paleozoic eras by reconstructing Rodinia and Pannotia, supercontinents that may have existed before and after the opening of the Pacific Ocean basin.
Abstract: The ever-changing distribution of continents and ocean basins on Earth is fundamental to the environment of the planet. Recent ideas regarding pre-Pangea geography and tectonics offer fresh opportunities to examine possible causative relations between tectonics and environmental and biologic changes during the Neoproterozoic and Paleozoic eras. The starting point is an appreciation that Laurentia, the rift-bounded Precambrian core of North America, could have been juxtaposed with the cratonic cores of some present-day southern continents. This has led to reconstructions of Rodinia and Pannotia, supercontinents that may have existed in early and latest Neoproterozoic time, respectively, before and after the opening of the Pacific Ocean basin. Recognition that the Precordillera of northwest Argentina constitutes a terrane derived from Laurentia may provide critical longitudinal control on the relations of that craton to Gondwana during the Precambrian-Cambrian boundary transition, and in the early Paleozoic. The Precordillera was most likely derived from the general area of the Ouachita embayment, and may have been part of a hypothetical promontory of Laurentia, the “Texas plateau,” which was detached from the Cape of Good Hope embayment within Gondwana between the present-day Falkland-Malvinas Plateau and Transantarctic Mountains margins. Thus the American continents may represent geometric “twins” detached from the Pannotian and Pangean supercontinents in Early Cambrian and Early Cretaceous time, respectively—the new mid-ocean ridge crests of those times initiating the two environmental supercycles of Phanerozoic history 400 m.y. apart. In this scenario, the extremity of the Texas plateau was detached from Laurentia during the Caradocian Epoch, in a rift event ca. 455 Ma that followed Middle Ordovician collision with the proto-Andean margin of Gondwana as part of the complex Indonesian-style Taconic-Famatinian orogeny, which involved several island arc-continent collisions between the two major continental entities. Laurentia then continued its clockwise relative motion around the proto-Andean margin, colliding with other arc terranes, Avalonia, and Baltica en route to the Ouachita-Alleghanian-Hercynian-Uralian collision that completed the amalgamation of Pangea. The important change in single-celled organisms at the Mesoproterozoic-Neoproterozoic boundary (1000 Ma) accompanied assembly of Rodinia along Grenvillian sutures. Possible divergence of metazoan phyla, the appearance and disappearance of the Ediacaran fauna (ca. 650–545 Ma), and the Cambrian “explosion” of skeletalized metazoans (ca. 545–500 Ma) also appear to have taken place within the framework of tectonic change of truly global proportions. These are the opening of the Pacific Ocean basin; uplift and erosion of orogens within the newly assembled Gondwana portion of Pannotia, including a collisional mountain range extending ≈7500 km from Arabia to the Pacific margin of Antarctica; the development of a Pannotia-splitting oceanic spreading ridge system nearly 10 000 km long as Laurentia broke away from Gondwana, Baltica, and Siberia; and initiation of subduction zones along thousands of kilometres of the South American and Antarctic-Australian continental margins. The Middle Ordovician sea-level changes and biologic radiation broadly coincided with initiation of the Appalachian-Andean mountain system along >7000 km of the Taconic and Famatinian belts. These correlations, based on testable paleogeographic reconstructions, invite further speculation about possible causative relations between the internally driven long-term tectonic evolution of the planet, its surface environment, and life.
TL;DR: It is suggested that podocyte loss contributes to the progression of diabetic nephropathy.
Abstract: Kidney biopsies from Pima Indians with type II diabetes were analyzed. Subjects were classified clinically as having early diabetes (n = 10), microalbuminuria (n = 17), normoalbuminuria, despite a duration of diabetes equal to that of the subjects with microalbuminuria (n = 12), or clinical nephropathy (n = 12). Subjects with microalbuminuria exhibited moderate increases in glomerular and mesangial volume when compared with those with early diabetes, but could not be distinguished from subjects who remained normoalbuminuric after an equal duration of diabetes. Subjects with clinical nephropathy exhibited global glomerular sclerosis and more prominent structural abnormalities in nonsclerosed glomeruli. Marked mesangial expansion was accompanied by a further increase in total glomerular volume. Glomerular capillary surface area remained stable, but the glomerular basement membrane thickness was increased and podocyte foot processes were broadened. Broadening of podocyte foot processes was associated with a reduction in the number of podocytes per glomerulus and an increase in the surface area covered by remaining podocytes. These findings suggest that podocyte loss contributes to the progression of diabetic nephropathy.
TL;DR: Once the authors have chosen to compare vision as a ratio using a reference visual angle (20/20), a geometric progression results and a geometric mean must be calculated for a meaningful result.
Abstract: C alculating the average visual acuity and standard deviation on a series of patients is not difficult , but has been done incorrectly in most studies. 1 The basic problem relates to the difference between the arithmetic and geometric mean for a set of numbers. For the correct average visual acuity, the geometric mean must be used, which gives significantly different values than the arithmetic mean. Modern visual acuity charts are designed so that the letter sizes on each line follow a geometric progression (ie, change in a uniform step on a logarithmic scale). 2-4 The accepted step size has been chosen to be 0.1 log unit steps, which is equivalent to letter sizes changing by a factor of 1.2589 between lines. This standard gave rise to the LogMAR (log of the minimum angle of resolution) notation, as shown in Table 1. A geometric progression of lines on the visual acuity chart was chosen because it parallels the way our visual system functions. If patient #1 has a visual acuity of 20/20 and patient #2 has a visual acuity of 20/40, we conclude that patient #1 has two times better visual acuity than patient #2 because he or she can recognize a letter twice as small. Once we have chosen to compare vision as a ratio using a reference visual angle (20/20), a geometric progression results and a geometric mean must be calculated for a meaningful result. Notice in Table 1 that the only values that increase linearly are the line numbers and the LogMar notation. The Snellen acuity, decimal acuity, and visual angle all increase by the geometric factor of 1.2589. Once we decide that equal steps in visual acuity measurement are geometric and not arithmetic , we must use the appropriate geometric mean to compute the correct average (Figure). In Table 1 and the Figure, we see that line 0 is the 20/20 Snellen acuity that corresponds to the LogMAR value zero, since 20/20 is the standard. We also see that line 10 is the 20/200 Snellen visual acuity that corresponds to a LogMAR value of +1.00 (ten times or 1 log unit worse than 20/20). Intuitively, it would appear that halfway between line 0 and line 10 would be line 5, or 20/63. This is the correct average, because geometrically it is halfway between 20/200 and 20/20. The two incorrect methods would be to take the arithmetic …
TL;DR: This paper examined the effects of partner nationality, organizational dissimilarity, and economic motivation on the dissolution of joint ventures, and event-history analysis was used to test the effect of these factors.
Abstract: This study examined the effects of partner nationality, organizational dissimilarity, and economic motivation on the dissolution of joint ventures. Event-history analysis was used to test the hypot...
01 Jan 1997
TL;DR: The data demonstrate a novel functional role for Caveolin-1 in mammalian cells as a potential molecular chaperone that directly inactivates NOS and the inactivation of eNOS and nNOS by the scaffolding domain of caveolin-3 suggests that eN OS in cardiac myocytes and n NOS in skeletal muscle are likely subject to negative regulation by this muscle-specific caveolin isoform.
TL;DR: This article argued that the epistemologies we typically use in educational research may be racially biased, and the lack of response is in curious contrast to the lively and contentious debates on other epistemological issues, such as quantitative versus qualitative, objectivity versus subjectivity, validity (e.g., Lenzo, 1995; Moss, 1994), or paradigmatic issues in general.
Abstract: espected scholars of color have suggested (e.g., Stanfield, 1985, 1993a, 1994), even within the pages of this journal (J. A. Banks, 1993, 1995; Gordon, Miller, & Rollock, 1990), that the epistemologies we typically use in educational research may be racially biased. They have argued that our epistemologiesl-not our use of them, but the epistemologies themselves-are racially biased ways of knowing, implicitly proposing, thus, a new category of racism that could be labeled epistemological racism. There has been, however, a provocative lack of response-pro or con-to this race-oriented argument by leading educational methodologists in journals of education, including this one.2 But this lack of response is in curious contrast to the lively and contentious debates on other epistemological issues, such as quantitative versus qualitative (e.g., Cizek, 1995), objectivity versus subjectivity (e.g., Heshusius, 1994), validity (e.g., Lenzo, 1995; Moss, 1994), or paradigmatic issues in general (e.g., Bereiter, 1994; Delandshere & Petrosky, 1994; Gage, 1989). If we were among those raising this race-oriented issue, we would wonder why our efforts to argue that the epistemologies of educational research were racially biased provoked virtually no response, particularly among those who author the quantitative and qualitative research methods textbooks we all typically use. We would certainly wonder whether our argument was ignored because it raised the disquieting issue of race, because it was thought to be a weak or irrelevant argument, or because the argument was simply not understood. Unfortunately, we might also wonder whether this was just one more incidence of Ellison's (1972) "invisible man" syndrome, of Whites ignoring racial issues and people of color. As researchers whose race is White and who have
01 Jun 1997
TL;DR: A simple randomized algorithm for accessing shared objects that tends to satisfy each access request with a nearby copy is designed, based on a novel mechanism to maintain and distribute information about object locations, and requires only a small amount of additional memory at each node.
Abstract: Consider a set of shared objects in a distributed network, where several copies of each object may exist at any given time. To ensure both fast access to the objects as well as efficient utilization of network resources, it is desirable that each access request be satisfied by a copy "close" to the requesting node. Unfortunately, it is not clear how to efficiently achieve this goal in a dynamic, distributed environment in which large numbers of objects are continuously being created, replicated, and destroyed. In this paper, we design a simple randomized algorithm for accessing shared objects that tends to satisfy each access request with a nearby copy. The algorithm is based on a novel mechanism to maintain and distribute information about object locations, and requires only a small amount of additional memory at each node. We analyze our access scheme for a class of cost functions that captures the hierarchical nature of wide-area networks. We show that under the particular cost model considered: (i) the expected cost of an individual access is asymptotically optimal, and (ii) if objects are sufficiently large, the memory used for objects dominates the additional memory used by our algorithm with high probability. We also address dynamic changes in both the network as well as the set of object copies.
TL;DR: The microencapsulation process in which the removal of the hydrophobic polymer solvent is achieved by evaporation has been widely reported in recent years for the preparation of microspheres and microcapsules based on biodegradable polymers and copolymers of hydroxy acids.
TL;DR: This poster presents a poster presented at the 2016 American Academy of Medical Oncology Congress on Wednesday, 3 March 2016 calling for awareness of the importance of informed consent in the selection of patients for cancer treatment.
TL;DR: Inhaled nitric oxide improves systemic oxygenation in infants with persistent pulmonary hypertension and may reduce the need for more invasive treatments.
Abstract: Background Persistent pulmonary hypertension of the newborn causes systemic arterial hypoxemia because of increased pulmonary vascular resistance and right-to-left shunting of deoxygenated blood. Inhaled nitric oxide decreases pulmonary vascular resistance in newborns. We studied whether inhaled nitric oxide decreases severe hypoxemia in infants with persistent pulmonary hypertension. Methods In a prospective, multicenter study, 58 full-term infants with severe hypoxemia and persistent pulmonary hypertension were randomly assigned to breathe either a control gas (nitrogen) or nitric oxide (80 parts per million), mixed with oxygen from a ventilator. If oxygenation increased after 20 minutes and systemic blood pressure did not decrease, the treatment was considered successful and was continued at lower concentrations. Otherwise, it was discontinued and alternative therapies, including extracorporeal membrane oxygenation, were used. Results Inhaled nitric oxide successfully doubled systemic oxygenation in 16 of 30 infants (53 percent), whereas conventional therapy without inhaled nitric oxide increased oxygenation in only 2 of 28 infants (7 percent). Long-term therapy with inhaled nitric oxide sustained systemic oxygenation in 75 percent of the infants who had initial improvement. Extracorporeal membrane oxygenation was required in 71 percent of the control group and 40 percent of the nitric oxide group (P=0.02). The number of deaths was similar in the two groups. Inhaled nitric oxide did not cause systemic hypotension or increase methemoglobin levels. Conclusions Inhaled nitric oxide improves systemic oxygenation in infants with persistent pulmonary hypertension and may reduce the need for more invasive treatments.
TL;DR: Results demonstrate that CCR2 is a major regulator of induced macrophage trafficking in vivo and shows enhanced early accumulation and delayed clearance of neutrophils and eosinophils.
Abstract: CC chemokine receptor 2 (CCR2) is a prominent receptor for the monocyte chemoattractant protein (MCP) group of CC chemokines. Mice generated by gene targeting to lack CCR2 exhibit normal leukocyte rolling but have a pronounced defect in MCP-1-induced leukocyte firm adhesion to microvascular endothelium and reduced leukocyte extravasation. Constitutive macrophage trafficking into the peritoneal cavity was not significantly different between CCR2-deficient and wild-type mice. However, after intraperitoneal thioglycollate injection, the number of peritoneal macrophages in CCR2-deficient mice did not rise above basal levels, whereas in wild-type mice the number of macrophages at 36 h was ≈3.5 times the basal level. The CCR2-deficient mice showed enhanced early accumulation and delayed clearance of neutrophils and eosinophils. However, by 5 days neutrophils and eosinophils in both CCR2-deficient and wild-type mice had returned to near basal levels, indicating that resolution of this inflammatory response can occur in the absence of macrophage influx and CCR2-mediated activation of the resident peritoneal macrophages. After intravenous injection with yeast β-glucan, wild-type mice formed numerous large, well-defined granulomas throughout the liver parenchyma, whereas CCR2-deficient mice had much fewer and smaller granulomas. These results demonstrate that CCR2 is a major regulator of induced macrophage trafficking in vivo.