Showing papers by "University of Louisville published in 1998"
TL;DR: A review of the biochemical and physiologic processes that regulate wound healing and the cascade of cellular events that gives rise to the healing process is presented here.
Abstract: In the last few decades, a great deal of progress has been made in understanding the cellular and biochemical interplay that comprises the normal wound healing response. This response is a complex process involving intricate interactions among a variety of different cell types, structural proteins, growth factors, and proteinases. The normal wound repair process consists of three phases--inflammation, proliferation, and remodeling--that occur in a predictable sequence and comprise a series of cellular and biochemical events. A review of the biochemical and physiologic processes that regulate wound healing and the cascade of cellular events that gives rise to the healing process is presented here.
906 citations
TL;DR: In this article, structural equation models are used to test a theory for research use in the human services and the results show that a non-recursive model positing a reciprocal relationship between research use and diffusion could not be confirmed.
Abstract: Structural Equation Modeling (SEM) is gaining attention in social work as an analytical method for studying social policy and testing theories for practice. This paper demonstrates a special SEM application to test a theory for research use in the human services. Data from 294 decision-makers in human service organizational units of federal, state, and local governments are used to show the appropriateness of using composites instead of multiple indicators in a SEM model with latent variables. The step-by-step description of a two-stage modeling process is presented. Using a model generation analysis strategy, the results show that a nonrecursive model positing a reciprocal relationship between research use and diffusion could not be confirmed. Instead, a recursive model is uncovered with research use leading to research diffusion. In addition, perceived quality of research, positive interaction between researchers and decision-makers, and transfer intensity of disseminating research results thro...
640 citations
TL;DR: Becaplermin gel 100 μg/g, in conjunction with good wound care, significantly increased the incidence of complete wound closure and significantly reduced the time to complete closure of chronic diabetic neuropathic ulcers.
Abstract: OBJECTIVE To compare the efficacy and safety of topically applied recombinant human platelet-derived growth factor-BB (rhPDGF-BB) (becaplermin) with placebo gel in patients with chronic diabetic neuropathic ulcers of the lower extremities. RESEARCH DESIGN AND METHODS This multicenter double-blind placebo-controlled phase 111 trial included 382 patients with type 1 or type 2 diabetes and chronic ulcers of at least 8 weeks9 duration. After sharp debridement of the ulcer, patients were randomized to receive becaplermin gel 30 μg/g, becaplermin gel 100 μg/g, or placebo gel, in conjunction with a standardized regimen of good wound care until complete wound closure was achieved or for a maximum of 20 weeks. Moist saline-soaked gauze dressings were changed twice daily with study medication applied by patients or caregivers at the evening dressing change. Safety was assessed by monitoring adverse events (AEs) and by clinical laboratory evaluations. RESULTS Compared with placebo gel, becaplermin gel 100 μg/g significantly increased the incidence of complete wound closure by 43% (50 vs. 35%, P = 0.007) and decreased the time to achieve complete wound closure by 32% (86 vs. 127 days; estimated 35th percentile, P = 0.013). AEs reported during treatment or during a 3-month follow-up period were similar in nature and incidence across all treatment groups. CONCLUSIONS Becaplermin gel 100 μg/g, in conjunction with good wound care, significantly increased the incidence of complete wound closure and significantly reduced the time to complete closure of chronic diabetic neuropathic ulcers. The safety profile of becaplermin gel was similar to that of placebo gel.
621 citations
TL;DR: In this paper, the authors examined how large corporate entities are making use of the Web to present themselves as socially responsible citizens and to advance their own policy positions and found that the number of social responsibility items on a web page was positively correlated with the size of an organization and the implementation of tools to make a web site more navigable, but was unrelated to a corporation's ranking within its industry.
549 citations
TL;DR: The results of this placebo-controlled trial showed that tramadol was effective and safe in treating the pain of diabetic neuropathy and no statistically significant treatment effects on sleep were identified.
Abstract: Objective The objective of this study was to evaluate the efficacy and safety of tramadol in treating the pain of diabetic neuropathy. Background The pain of diabetic neuropathy is a major cause of morbidity among these patients and treatment, as with other small-fiber neuropathies, is often unsatisfactory. Tramadol is a centrally acting analgesic for use in treating moderate to moderately severe pain. Methods This multicenter, outpatient, randomized, double-blind, placebo-controlled, parallel-group study consisted of a washoutlscreening phase, during which all analgesics were discontinued, and a 42-day double-blind treatment phase. A total of 131 patients with painful diabetic neuropathy were treated with tramadol (n = 65) or placebo (n = 66) tramadol, which were administered as identical capsules in divided doses four times daily. The primary efficacy analysis compared the mean pain intensity scores in the tramadol and placebo groups obtained at day 42 of the study or at the time of discontinuation. Secondary efficacy assessments were the pain relief rating scores and a quality of life evaluation based on daily activities and sleep characteristics. Results Tramadol, at an average dosage of 210 mg/day, was significantly ( p p = 0.02) and social functioning (p = 0.04) ratings than patients in the placebo group. No statistically significant treatment effects on sleep were identified. The most frequently occurring adverse events with tramadol were nausea, constipation, headache, and somnolence. Conclusions The results of this placebo-controlled trial showed that tramadol was effective and safe in treating the pain of diabetic neuropathy.
507 citations
TL;DR: Although always present, ventricular interdependence is most apparent with sudden postural and respiratory changes in ventricular volume, and is probably best explained by the balance of forces at the interventricular sulcus, the material properties, and cardiac dimensions.
476 citations
Journal Article•
TL;DR: The results provide strong support for the hypothesis that Abeta is neurotoxic in vivo and that such toxicity is mediated by free radicals and validate the transgenic approach for the study of oxidative stress in AD and for the evaluation of antioxidant therapies in vivo.
Abstract: Increased expression of antioxidant enzymes and heat-shock proteins are key markers of oxidative stress Such proteins are abnormally present within the neuropathological lesions of Alzheimer's disease (AD), suggesting that oxidative stress may play significant but yet undefined roles in this disorder To gain further insight into the role of oxidative stress in AD, we studied the expression of CuZn superoxide dismutase (SOD) and hemoxygenase-1 (HO-1), two established markers of oxidative stress, in a transgenic mouse model of AD Immunohistochemistry with anti-SOD and anti-HO-1 antibodies revealed a very pronounced increase of these proteins only in aged transgene-positive mice Interestingly, the distribution of the oxidative burden was largely overlapping with dystrophic neuritic elements in the mice as highlighted with anti-ubiquitin antibodies Because the most conspicuous alterations were identified around amyloid (Abeta) deposits, our results provide strong support for the hypothesis that Abeta is neurotoxic in vivo and that such toxicity is mediated by free radicals To obtain additional experimental evidence for such an interpretation (ie, a cause-effect relationship between Abeta and oxidative neurotoxicity), PC12 cells were exposed to increasing concentrations of Abeta or to oxidative stress In agreement with the in vivo findings, either treatment caused marked induction of SOD or HO-1 in a dose-dependent fashion These results validate the transgenic approach for the study of oxidative stress in AD and for the evaluation of antioxidant therapies in vivo
345 citations
TL;DR: The data suggest that the local expression of MIP‐2 and KC are important mediators involved in neutrophil‐dependent hepatic injury induced by ischemia and reperfusion in mice.
336 citations
TL;DR: The data suggest that nonsteroidal anti‐inflammatory drugs significantly inhibit spinal fusion at doses typically used for postoperative pain control, and recommend that these drugs be avoided in the early postoperative period.
Abstract: Study design The influence of ketorolac on spinal fusion was studied in a retrospective review of 288 patients who underwent an instrumented spinal fusion. Objective To assess the effect of postoperative ketorolac administration on subsequent fusion rates. Summary of background data Nonsteroidal anti-inflammatory drugs are widely used compounds, which are known to inhibit osteogenic activity and have been shown to decrease spinal fusion in an animal model. No previous studies have examined the influence of nonsteroidal anti-inflammatory drugs on spinal fusion in clinical practice. Methods The medical records of 288 patients who underwent instrumented spinal fusion from L4 to the sacrum between 1991 and 1993 were reviewed retrospectively. The 121 patients who received no nonsteroidal anti-inflammatory drugs were compared with the 167 patients who received ketorolac after surgery. The groups were demographically equivalent. Results Ketorolac had a significant adverse effect on fusion, with five nonunions in the nondrug group and 29 nonunions in the ketorolac group (P > 0.001). Ketorolac administration also significantly decreased the fusion rate for subgroups including men, women, smokers, and nonsmokers. The odds ratio demonstrated that nonunion was approximately five times more likely after ketorolac administration. Cigarette smoking also decreased the fusion rate (P > 0.01); smokers were 2.8 times more likely to develop nonunion. Conclusion These data suggest that nonsteroidal anti-inflammatory drugs significantly inhibit spinal fusion at doses typically used for postoperative pain control. The authors recommend that these drugs be avoided in the early postoperative period.
309 citations
TL;DR: In this article, a conceptual model for the evaluation of periphyton communities in unshaded temperate streams based on the primary habitat variables of flood disturbance, nutrient resource supply and invertebrate grazing is proposed.
Abstract: In this paper we suggest a conceptual model for the evaluation of periphyton communities in unshaded temperate streams based on the primary habitat variables of flood disturbance, nutrient resource supply and invertebrate grazing. The core of this model is a classification of 35 periphyton taxa into four main functional groups based on the C-S-R life history strategies of Grime. Possible successional trajectories following system-wide disturbances under different nutrient supply regimes are also discussed. The interaction of disturbance and nutrient supply on species membership, productivity and accrual time results in a predicted gradient from low biomass in frequently disturbed, unenriched habitats to high biomass in infrequently disturbed, enriched habitats. This prediction is verified empirically using literature data. Herbivory can strongly modify such periphyton responses to disturbance and resource supply. However, these grazing effects could vary greatly depending on the dominant invertebrate grazer and their total abundance, which inturn, is also sensitive to changes in disturbance and nutrient resource supply. This interaction is also discussed. The conceptual model complements other more general habitat templet and dynamic equilibrium concepts in ecology.
301 citations
TL;DR: Sentinel-lymph-node biopsy has become a standard technique for determining the nodal stage of disease in patients with melanoma and is suggested to be a viable option for breast cancer patients.
Abstract: A sentinel lymph node is the first lymph node to receive lymphatic drainage from a tumor. It can be detected by injection of a blue dye or radioactive colloid around the primary tumor, which travels to and identifies the first draining (sentinel) node. Biopsy of a sentinel lymph node can reveal whether there are lymphatic metastases, thereby obviating the need for extensive dissection of the regional lymph-node basin. Sentinel-lymph-node biopsy has become a standard technique for determining the nodal stage of disease in patients with melanoma. Initial studies of this method in patients with breast cancer suggest that sentinel-lymph-node biopsy . . .
TL;DR: Treatment of chronic wounds should be directed against the main etiologic factors responsible for the wound, and factors that may impede healing must be identified and, if possible, corrected, for healing to occur.
Abstract: Chronic wounds will often heal in a short period of time if factors that inhibit wound healing are identified and managed. Recombinant growth factor therapy may provide an added stimulus to healing in certain types of chronic wounds. However, there remains no substitute for a physiologic environment conducive to tissue repair and regeneration, without which the efficacy of growth factor therapy is questionable. Some of the most commonly encountered and clinically significant impediments to wound healing include wound hypoxia, infection, presence of debris and necrotic tissue, use of anti-inflammatory medications, a diet deficient in vitamins or minerals, or general nutritional deficiencies, tumors, environmental factors, and metabolic disorders, such as diabetes mellitus. Treatment of chronic wounds should be directed against the main etiologic factors responsible for the wound. Moreover, factors that may impede healing must be identified and, if possible, corrected, for healing to occur.
TL;DR: In this article, the authors analyzed specific social activities, aspects of neighborhoods, and contribution of each to the risks of larceny victimization for college students, and found that greater specificity in measuring lifestyles is warranted, for it is not just leaving one's home and going out in public that increases one's risk for victimization (a typical finding of routine activity theory scholars), but where one goes and what one does that are the important larcene victimization predictors.
Abstract: Routine activity theory has long been plagued by a heavy reliance on proxy measures of lifestyles, which typically include demographic variables that are regularly used as measures of lifestyle and behavior. This reliance on indirect measures forces researchers to suppose how and why these indicators are related to victimization risks. Using detailed measurements of activities and specific structural aspects of communities is clearly more desirable and beneficial when seeking to explain variances in victimization risks. This research advances theoretical understandings of victimization risks through an analysis of specific social activities, aspects of neighborhoods, and contribution of each to the risks of larceny victimization for college students. We find that greater specificity in measuring lifestyles is warranted, for it is not just leaving one's home and going out in public that increases one's risk for victimization (a typical finding of routine activity theory scholars), but where one goes and what one does that are the important larceny victimization predictors.
TL;DR: The NO hypothesis of late PC puts forth a comprehensive paradigm that can explain both the initiation and the mediation of this complex phenomenon, and has potential clinical reverberations, since NO donors are widely used clinically and could be used to protect the ischemic myocardium in patients.
Abstract: Ischemic preconditioning (PC) occurs in two phases: an early phase, which lasts 2–3 h, and a late phase, which begins 12–24 h later and lasts 3–4 days. The mechanism for the late phase of PC has been the subject of intensive investigation. We have recently proposed the “NO hypothesis of late PC”, which postulates that NO plays a prominent role both in initiating and in mediating this cardioprotective response. The purpose of this essay is to review the evidence supporting the NO hypothesis of late PC and to discuss its implications. We propose that, on day 1, a brief ischemic stress causes increased production of NO (probably via eNOS) and ·O2
–, which then react to form ONOO–, ONOO–, in turn, activates the ɛ isoform of protein kinase C (PKC); either directly or via its reactive byproducts such as ·OH. Both NO and secondary species derived from ·O2
– could also stimulate PKC ɛ independently. PKC ɛ activation triggers a complex signaling cascade that involves tyrosine kinases (among which Src and Lck appear to be involved) and probably other kinases, the transcription factor NF-κB, and most likely other as yet unknown components, resulting in increases transcription of the iNOS gene and increased iNOS activity on day 2, which is responsible for the protection during the second ischemic challenge. Tyrosine kinases also appear to be involved on day 2, possibly by modulating iNOS activity. According to this paradigm, NO plays two completely different roles in late PC: on day 1, it initiates the development of this response, whereas on day 2, it protects against myocardial ischemia. We propose that two different NOS isoforms are sequentially involved in late PC, with eNOS generating the NO that initiates the development of the PC response on day 1 and iNOS then generating the NO that protects against recurrent ischemia on day 2. The NO hypothesis of late PC puts forth a comprehensive paradigm that can explain both the initiation and the mediation of this complex phenomenon. Besides its pathophysiological implications, this hypothesis has potential clinical reverberations, since NO donors (i.e., nitrates) are widely used clinically and could be used to protect the ischemic myocardium in patients.
TL;DR: Results indicate that in the conscious rabbit, the infarct-sparing effect of the late phase of ischemic PC is mediated by the activity of NOS and suggest that the specific isoform primarily responsible for this cardioprotective phenomenon is iNOS.
Abstract: Background —Despite intense investigation, the effector of the infarct-limiting protection observed during the late phase of ischemic preconditioning (PC) remains unknown. The goal of this study was to test the hypothesis that late PC against myocardial infarction is mediated by the activity of nitric oxide synthase (NOS).
Methods and Results —Conscious rabbits underwent a 30-minute coronary occlusion followed by 3 days of reperfusion. In group I (control group, n=10), infarct size (tetrazolium staining) averaged 56.8±5.3% of the risk region, which was decreased to 27.6±2.5% ( P <0.05) in rabbits preconditioned 24 hours earlier with a sequence of six 4-minute occlusion/4-minute reperfusion cycles (group II, n=10). When preconditioned rabbits were given the nonselective NOS inhibitor N ω-nitro-l-arginine (L-NA, 13 mg/kg IV [group III, n=8]) or the selective iNOS inhibitor aminoguanidine (AG, 150 mg/kg SC [group V, n=7]) before the 30-minute occlusion, the protective effect of late PC was completely abrogated; that is, infarct size (59.9±4.5% and 65.8±3.3%, respectively) was similar to that measured in the control group. Measurements of systolic wall thickening (sonomicrometry) demonstrated that L-NA and AG also abolished the improved recovery of myocardial function effected by late PC in group II. When rabbits were given L-NA or AG without prior PC (group IV [n=8] and group VI [n=6], respectively), infarct size did not differ from that observed in controls (53.8±4.3% and 59.8±4.3%, respectively), demonstrating that L-NA and AG do not increase the extent of cell death in nonpreconditioned myocardium.
Conclusions —Taken together, these results indicate that in the conscious rabbit, the infarct-sparing effect of the late phase of ischemic PC is mediated by the activity of NOS and suggest that the specific isoform primarily responsible for this cardioprotective phenomenon is iNOS. Thus, NO appears to be a pivotal component of the pathophysiological cascade of late PC.
TL;DR: The presence of specialized marsupial patterns of tooth replacement and cranial vascularization in Deltatheridium and the basal phylogenetic position of this taxon indicate that these features are characteristic of Metatheria as a whole.
Abstract: We describe here two new specimens of the mammal Deltatheridium pretrituberculare from the Late Cretaceous period of Mongolia. These specimens provide information on tooth replacement in basal therian mammals and on lower jaw and basicranial morphology. Deltatheroidans, known previously from isolated teeth, partial rostra and jaws from the late Cretaceous of Asia1,2,3,4 and possibly North America5,6, have been identified variously as eutherians1,7,8, as basal metatherians (the stem-based clade formed by marsupials and their extinct relatives)3,9,10,11, or as an outgroup to both eutherians and metatherians2,12,13,14,15. Resolution of these conflicting hypotheses and understanding of the early evolution of the therian lineage have been hampered by a sparse fossil record for basal therians. The new evidence supports metatherian affinities for deltatheroidans and allows a comprehensive phylogenetic analysis of basal metatherians and marsupials. The presence of specialized marsupial patterns of tooth replacement and cranial vascularization in Deltatheridium and the basal phylogenetic position of this taxon indicate that these features are characteristic of Metatheria as a whole. Other morphological transformations recognized here secure the previously elusive diagnosis of Metatheria3,14,15. The new specimens of Deltatheridium illustrate the effectiveness of fairly complete fossil specimens in determining the nature of early evolutionary events.
TL;DR: An overview of vomeronasal system organization is presented and the history of the discovery of mammalian AOB is reviewed, and the evolutionary origin and diversity of the AOB in mammalian orders and species is discussed.
Abstract: The accessory olfactory bulb (AOB) is the first neural integrative center for the olfactory-like vomeronasal sensory system. In this article, we first briefly present an overview of vomeronasal system organization and review the history of the discovery of mammalian AOB. Next, we briefly review the evolution of the vomeronasal system in vertebrates, in particular the reptiles. Following these introductory aspects, the structure of the rodent AOB, as typical of the well-developed mammalian AOB, is presented, detailing laminar organization and cell types as well as aspects of the homology with the main olfactory bulb. Then, the evolutionary origin and diversity of the AOB in mammalian orders and species is discussed, describing structural, phylogenetic, and species-specific variation in the AOB location, shape, and size and morphologic differentiation and development. The AOB is believed to be absent in fishes but present in terrestrial tetrapods including amphibians; among the reptiles AOB is absent in crocodiles, present in turtles, snakes, and some lizards where it may be as large or larger than the main bulb. The AOB is absent in bird and in the aquatic mammals (whales, porpoises, manatees). Among other mammals, AOB is present in the monotremes and marsupials, edentates, and in the majority of the placental mammals like carnivores, herbivores, as well as rodents and lagomorphs. Most bat species do not have an AOB and among those where one is found, it shows marked variation in size and morphologic development. Among insectivores and primates, AOB shows marked variation in occurrence, size, and morphologic development. It is small in shrews and moles, large in hedgehogs and prosimians; AOB continues to persist in New World monkeys but is not found in the adults of the higher primates such as the Old World monkeys, apes, and humans. In many species where AOB is absent in the adult, it often develops in the embryo and fetus but regresses in later stages of development. Finally, new areas in vomeronasal system research such as the diversity of receptor molecules and the regional variation in receptor neuron type as well as in the output neurons of the AOB and their projection pathways are briefly discussed. In view of the pronounced diversity of size, morphologic differentiation, and phylogenetic development, the need to explore new functions for the vomeronasal system in areas other than sexual and reproductive behaviors is emphasized.
TL;DR: Results demonstrate that in conscious rabbits the administration of 2 structurally unrelated NO donors induces protection 24 hours later against both reversible (stunning) and irreversible (infarction) ischemia/reperfusion injury and that the magnitude of this protection is indistinguishable from that observed during the late phase of ischemic PC.
Abstract: —The goal of this study was to test the hypothesis that the cardioprotective effects of the late phase of ischemic preconditioning (PC) can be mimicked by treatment with NO donors. In phase I (studies of myocardial stunning), conscious rabbits underwent a sequence of six 4-minute coronary occlusion/4-minute reperfusion cycles for 3 consecutive days (days 1, 2, and 3). In group I (controls, n=6), the total deficit of systolic wall thickening (WTh) after the sixth reperfusion was reduced by 54% on days 2 and 3 compared with day 1 ( P <0.05), indicating a late PC effect against myocardial stunning. When rabbits were given the NO donors diethylenetriamine/NO (DETA/NO, 0.1 mg/kg IV, 4 times [group II, n=5]) or S -nitroso- N -acetylpenicillamine (SNAP, 2.5 μg · kg−1 · min−1 IV for 75 minutes [group III, n=5]) 24 hours before the first sequence of occlusion/reperfusion cycles, the deficit of WTh on day 1 was 60% (group II) and 54% (group III) less than that observed in controls ( P <0.05 for both). In both groups II and III, there was no further improvement in the deficit of WTh on days 2 and 3 compared with day 1. The protective effect of DETA/NO was completely abrogated when this agent was given in conjunction with the ONOO− and ·OH scavenger mercaptopropionyl glycine (MPG) (group IV, n=5). In phase II (studies of myocardial infarction), conscious rabbits underwent a 30-minute coronary occlusion followed by 3 days of reperfusion. When rabbits were preconditioned 24 hours earlier with six 4-minute occlusion/4-minute reperfusion cycles, infarct size was reduced by 43% (33.2±2.7% versus 58.3±4.1% of the region at risk in controls, P <0.05), indicating a late PC effect against myocardial infarction. When rabbits were pretreated with DETA/NO (group VII, n=8) or SNAP (group IX, n=7) 24 hours before the 30-minute occlusion, infarct size was reduced by a similar degree (29.3±3.6% and 32.0±3.3% of the region at risk, respectively; P <0.05 versus controls). The degree of protection could not be increased by doubling the dose of DETA/NO (group VIII, n=5). Coadministration of MPG completely abrogated the infarct-sparing action of DETA/NO (group X, n=7). Taken together, these results demonstrate that in conscious rabbits the administration of 2 structurally unrelated NO donors induces protection 24 hours later against both reversible (stunning) and irreversible (infarction) ischemia/reperfusion injury and that the magnitude of this protection is indistinguishable from that observed during the late phase of ischemic PC. The fact that the late phase of ischemic PC can be mimicked by NO donors provides direct evidence that NO in itself is sufficient to elicit this cardioprotective mechanism. The fact that NO donor–induced late PC was abrogated by MPG indicates that the mechanism whereby NO induces this phenomenon involves the generation of oxidant species, possibly ONOO– and/or ·OH. Since a relatively brief treatment with hemodynamically inactive doses of NO donors can induce long-lasting protective effects, these agents could be useful for preconditioning the heart in patients.
TL;DR: In this paper, the authors examined whether cost-reducing innovations are more likely to be observed in regimes of more intense (Bertrand) or less intense (Cournot) competition.
TL;DR: Regression analyses indicated that role strain was related to marital satisfaction and depression and that recreation time accounted for additional variance, and path analysis suggested that recreation mediated the negative relationship between role strain and distress.
Abstract: This study examined marital role strain in 33 couples caring for a child with cystic fibrosis (CF) and 33 couples with a healthy child. The relationship between role strain, marital satisfaction, and psychological distress was tested. Couples completed a structured interview, questionnaires, a card sort procedure, and 4 daily diaries assessing activities and mood. Couples in the CF versus comparison group reported greater role strain on measures of role conflict, child-care tasks, and exchanges of affection. They also spent less time in recreational activities, but no reliable group differences were found in marital satisfaction or depression. Regression analyses indicated that role strain was related to marital satisfaction and depression and that recreation time accounted for additional variance. Path analysis suggested that recreation mediated the negative relationship between role strain and distress. The importance of using a contextual, process-oriented approach is discussed.
TL;DR: The RPM, which emphasizes the primary role of autotrophic production in large rivers, is the most viable of the remaining two ecosystem models for the constricted-channel region of the Ohio based on stable isotope linkage between sources and consumers of organic matter in the food web.
Abstract: Analyses of stable isotope (δ13C and δ15N) and C:N ratios of food webs within a floodplain and a constricted-channel region of the Ohio River during October 1993 and July 1994 indicate that the increasingly influential flood pulse concept (FPC) does not, for either location, adequately address food web structure for this very large river Furthermore, results of this study suggest that the riverine productivity model (RPM) is more appropriate than the widely known river continuum concept (RCC) for the constricted region of this river These␣conclusions are based on stable isotope analyses of potential sources of organic matter (riparian C3 trees, riparian C4 grasses and agricultural crops, submerged macrophytes, benthic filamentous algae, benthic particulate organic matter, and transported organic matter containing detritus and phytoplankton) and various functional feeding groups of invertebrate and fish consumers The FPC, which stresses the key contribution of organic matter, particularly terrestrial organic matter, originating from the floodplain to riverine food webs, was judged inappropriate for the floodplain region of the Ohio River for hydrodynamic and biotic reasons The rising limb and peak period of discharge typically occur in November through March when temperatures are low (generally much less than 10°C) and greater than bank-full conditions are relatively unpredictable and short-lived The major food potentially available to riverine organisms migrating into the floodplain would be decaying vegetation because autotrophic production is temperature and light limited and terrestrial insect production is minimal at that time It is clear from our data that terrestrial C4 plants contribute little, if anything, to the consumer food web (based on δ13C values), and δ15N values for C3 plants, coarse benthic organic matter, and fine benthic organic matter were too depleted (∼7-12‰ lower than most invertebrate consumer values) for this organic matter to be supporting the food web The RPM, which emphasizes the primary role of autotrophic production in large rivers, is the most viable of the remaining two ecosystem models for the constricted-channel region of the Ohio based on stable isotope linkage between sources and consumers of organic matter in the food web The most important form of food web organic matter is apparently transported (suspended) fine (FTOM) and ultra-fine particulate organic matter We propose that phytoplankton and detritus of an autochthonous origin in the seston would represent a more usable energy source for benthic (bivalve molluscs, hydropsychid caddisflies) and planktonic (microcrustaceans) suspension feeders than the more refractory allochthonous materials derived from upstream processing of terrestrial organic matter Benthic grazers depend heavily on nonfilamentous benthic algae (based on gut analysis from a separate study), but filamentous benthic algae have no apparent connection to invertebrate consumers (based on δ13C values) Amphipod and crayfish show a strong relationship to aquatic macrophytes (possibly through detrital organic matter rather than living plant tissue) These observations contrast with the prediction of the RCC that food webs in large rivers are based principally on refractory FTOM and dissolved organic matter from upstream inefficiencies in organic-matter processing and the bacteria growing upon these suspended or dissolved detrital compounds The conclusions drawn here for the Ohio River cannot yet be extended to other floodplain and constricted-channel rivers in temperate and tropical latitudes until more comparable data are available on relatively pristine and moderately regulated rivers
TL;DR: Human psychophysical performance in perceiving absolute distance and in visually directed action tasks is studied to provide support for a view that the brain could use a quasi-two-dimensional coordinate system with respect to the ground surface, rather than a strictly three- dimensional coordinate system, thus reducing coding redundancy and simplifying computations.
Abstract: Mathematically, three-dimensional space can be represented differently by the cartesian, polar, and other coordinate systems However, in physical sciences, the choice of representation system is restricted by the need to simplify a machine's computation while enhancing its efficiency Does the brain, for the same reasons, 'select' the most cost-efficient way to represent the three-dimensional location of objects? As we frequently interact with objects on the common ground surface, it might be beneficial for the visual system to code an object's location using a ground-surface-based reference frame More precisely, the brain could use a quasi-two-dimensional coordinate system (x(s), y(s)) with respect to the ground surface (s), rather than a strictly three-dimensional coordinate system (x, y, z), thus reducing coding redundancy and simplifying computations Here we provide support for this view by studying human psychophysical performance in perceiving absolute distance and in visually directed action tasks For example, when an object was seen on a continuous, homogeneous texture ground surface, the observer judged the distance to the object accurately However, when similar surface information was unavailable, for example, when the object was seen across a gap in the ground, or across distinct texture regions, distance judgement was impaired
TL;DR: Data provide strong evidence that KCNE1 mutations represent a fifth LQTS locus (LQT5), and further functional analysis, as well as the identification of more LQ TS patients with KC NE1 mutations, will be important to confirm the role of IsK in LQts.
Abstract: Background—Long-QT syndrome (LQTS) is a disorder of ventricular repolarization characterized by a prolonged QT interval, syncope, seizures, and sudden death. Recently, three forms of LQTS have been...
TL;DR: It is proposed that the genesis of extracellular membrane vesicles in Gram-negative bacteria is a result of cell wall turnover, and peptidoglycan turnover would cause a turgor on the outer membranes, causing the outer membrane to bulge and finally bleb.
Abstract: It is proposed that the genesis of extracellular membrane vesicles in Gram-negative bacteria is a result of cell wall turnover. Peptidoglycan turnover would cause a turgor on the outer membrane, causing the outer membrane to bulge and finally bleb. Mechanical motion would then shear the blebs into the culture medium.
TL;DR: Analysis by subcellular fractionation and morphological techniques showed that the Na/Pi cotransporter is constitutively transported to and degraded within late endosomes/lysosomes and that PTH leads to the increased degradation of the transporter in late endo-lysosome.
Abstract: We have studied the involvement of proteolytic pathways in the regulation of the Na/Pi cotransporter type II by parathyroid hormone (PTH) in opossum kidney cells. Inhibition of lysosomal degradation (by leupeptin, ammonium chloride, methylamine, chloroquine, l-methionine methyl ester) prevented the PTH-mediated degradation of the transporter, whereas inhibition of the proteasomal pathway (by lactacystin) did not. Moreover it was found (i) that whereas lysosomal inhibitors prevented the PTH-mediated degradation of the transporter they did not prevent the PTH-mediated inhibition of the Na/Pi cotransport and (ii) that treating opossum kidney cells with lysosomal inhibitors led to an increased expression of the transporter without any concomitant increase in the Na/Pi cotransport. Further analysis by subcellular fractionation and morphological techniques showed (i) that the Na/Pi cotransporter is constitutively transported to and degraded within late endosomes/lysosomes and (ii) that PTH leads to the increased degradation of the transporter in late endosomes/lysosomes.
TL;DR: It is demonstrated that, in the mouse, a robust infarct-sparing effect occurs during both the early and the late phases of ischemic PC, although the early phase is more powerful.
Abstract: It is unknown whether ischemic preconditioning (PC; either early or late) occurs in the mouse. The goal of this study was to answer this question and to develop a reliable and physiologically relevant murine model of both early and late ischemic PC. A total of 201 mice were used. In nonpreconditioned open-chest animals subjected to 30 min of coronary occlusion followed by 24 h of reperfusion, infarct size (tetrazolium staining) averaged 52% of the region at risk. When the 30-min occlusion was performed 10 min after a PC protocol consisting of six cycles of 4-min occlusion and 4-min reperfusion, infarct size was reduced by 75%, indicating an early PC effect. When the 30-min occlusion was performed 24 h after the same PC protocol, infarct size was reduced by 48%, indicating a late PC effect. In mice in which the 30-min occlusion was followed by 4 h of reperfusion, infarct size was similar to that observed after 24 h of reperfusion, indicating that a 4-h reperfusion interval is sufficient to detect the final extent of cell death in this model. Fundamental physiological variables (body temperature, arterial oxygenation, acid-base balance, heart rate, and arterial pressure) were measured and found to be within normal limits. Taken together, these results demonstrate that, in the mouse, a robust infarct-sparing effect occurs during both the early and the late phases of ischemic PC, although the early phase is more powerful. This murine model is physiologically relevant, provides reliable measurements, and should be useful for elucidating the cellular mechanisms of ischemic PC in genetically engineered animals.
TL;DR: The human dental arch form is shown to be accurately represented mathematically by the beta function, which more accurately described the dental Arch form than representations previously reported.
Abstract: The human dental arch form is shown to be accurately represented mathematically by the beta function. The average correlation coefficient between measured arch-shape data and the mathematical arch shape, expressed by the beta function, is 0.98 with a standard deviation of 0.02. Forty sets of casts—15 Class I, 16 Class II, and 9 Class III—were examined. A precision machine tool device was used to record the X-, Y-, and Z-coordinates of selected dental landmarks on all casts to 0.001 mm accuracy. The coordinates were processed through a computer curve-fitting program. The Class III mandibular arches had smaller arch depth and greater arch width (beginning in the premolar area) than the Class I arches. The Class II mandibular arches exhibited generalized reduced arch width and depth compared with the Class I arches. Maxillary arch depths were similar in all three groups. However, the Class III maxillary arch widths were greater from the lateral incisor-canine area distally compared with the Class I ...
TL;DR: It is demonstrated that rabbit and human conjunctival cells contain functional P2Y2 (formerly designated as P2U) nucleotide receptors that govern mucin secretion, which may provide useful pharmacological targets for therapeutic modulation of tear film mucins in dry-eye disorders and/or corneal wound healing.
TL;DR: The Florida Everglades is an extensive subtropical wetland that formed during the past 5000 years through the process of peat and marl accretion within a limestone depression that has been altered dramatically by the rapid human development in south Florida during the 20th century.
Abstract: The Florida Everglades is an extensive subtropical wetland that formed during the past 5000 years through the process of peat and marl accretion within a limestone depression (Gleason and Stone 1994). This wetland once covered approximately 10,000 km2 of the south Florida peninsula and extended uninterrupted from Lake Okeechobee to Florida Bay (Fig. 1). The freshwater Everglades is composed of extensive stands of sawgrass (Cladium jamaicense Crantz) and other emergent macrophytes interspersed with open-water sloughs containing abundant periphyton. This vegetative mosaic supports a productive food web including some of the largest concentrations of wading birds in the southeastern United States (Robertson and Frederick 1994). The ecological features of the Everglades developed under a hydrologic regime of seasonal inundation and drying coupled with low rates of nutrient loading, which allowed for the maintenance of oligotrophic conditions (Parker 1974, Davis 1994). These conditions have been altered dramatically by the rapid human development in south Florida during the 20th century. Approximately half of the wetland has been drained for agricultural and urban use by a network of canals and levees that transformed the once free-flowing ‘‘river of grass’’ into a series of diked marshes (Fig. 1) and altered the quantity and timing of water flows throughout much of the system. Canals also have served as conduits for agricultural and urban runoff, which contain elevated nutrient concentrations compared to the marsh (Waller and Earle 1975, McCormick et al. 1996). Human-induced changes in marsh hydrology and
TL;DR: Patients in long-term acute care facilities routinely are overfed and underfed, with only 25% receiving calories within 10% of required needs, and the use of IC to determine caloric requirements may result in significant cost savings.
Abstract: BACKGROUND Specific morbidity related to underfeeding and overfeeding necessitates the design of nutrition support regimens that provide calories equal to those required on the basis of energy expenditure. This prospective multicenter trial was designed to determine what percent of patients in long-term acute care facilities receive feeding appropriate to their needs and whether accuracy of feeding has an impact on patient clinical status. METHODS Patients on mechanical ventilation who were hospitalized at 32 Vencor Hospitals over a 9-week period and who were receiving only enteral nutrition by continuous infusion at a presumed goal rate were evaluated once by indirect calorimetry (IC) while on feeding. Caloric intake over the preceding 24 hours was determined by physician orders and by patient intake/output (I/O) record. Caloric requirements were defined by measured resting energy expenditure (REE) + 10% for activity. Degree of metabolism was defined by the ratio: (measured REE/Harris-Benedict predicted REE) x 100, and the degree of feeding by the ratio: (calories provided/calories required) x 100. RESULTS IC was performed on 335 patients (mean, 11.2 patients per center; range, 1 to 32), of which 72 were excluded for nonphysiological results or failure to achieve steady state, 21 for receiving parenteral nutrition, and 29 for not being on mechanical ventilation at time of testing. The 213 study patients were 58.7% male with mean age 70.1 years (range, 20 to 90 years). Measured REE was 110% of required calories, and 12.2% were underfed, receiving <90% of requirements. Discrepancies based on I/O records, however, suggested that 36.1% of patients received <90% of those calories ordered. By either basis, only about 25% of patients received feeding within 10% of required calories. The percent of patients being overfed varied between centers, ranging from 32.2% to 92.8%, and was not affected by years of facility IC experience or volume of IC studies per month. The pattern of caloric provision as measured by degree of feeding correlated inversely to degree of metabolism (p < .0001, R2 = .24). Accuracy of feeding had an impact on ventilatory status, as degree of feeding correlated inversely with minute ventilation (p = .001, R2 = .05). Degree of overfeeding also led to significant increases in azotemia (p = .033, R2 = .02). Extrapolating study data over 1 year, reduction in excess volume of enteral formula would have resulted in a cost savings of up to $1.3 million for the Vencor system. CONCLUSIONS Because energy expenditure is difficult to predict on the basis of conventional equations, patients in long-term acute care facilities routinely are overfed and underfed, with only 25% receiving calories within 10% of required needs. Measuring a patient's energy requirement at least once by IC is important, because the degree of metabolism predicts how easily a patient will be underfed or overfed. The amount of infused calories should be compared with caloric requirements measured by IC, because the accuracy or degree of underfeeding or overfeeding has an impact on ventilatory status and the likelihood for developing azotemia. Although physician practice or bias may reduce the optimal clinical effect, the use of IC to determine caloric requirements may result in significant cost savings.