1 In the Great Basin of the western United States of America, the invasive annual grass Bromus tectorum has extensively replaced native shrub and bunchgrass communities, but the native bunchgrass ...Elymus elymoides has been reported to suppress Bromus. Curlew Valley, a site in Northern Utah, provides a model community to test the effects of particular species on invasion by examining competitive relationships among Elymus, Bromus and the native shrub Artemisia tridentata. 2 The site contains Bromus/Elymus, Elymus/Artemisia and monodominant Elymus stands. Transect data indicate that Elymus suppresses Bromus disproportionately relative to its above-ground cover. Artemisia seedlings recruit in Elymus stands but rarely in the presence of Bromus. This relationship might be explained by competition between the two grasses involving a different resource or occurring in a different season to that between each grass and Artemisia. 3 Time reflectometry data collected in monodominant patches indicated that in spring, soil moisture use by Bromus is rapid, whereas depletion under Elymus and Artemisia is more moderate. Artemisia seedlings may therefore encounter a similar moisture environment in monodominant or mixed perennial stands. However, efficient autumn soil moisture use by Elymus may help suppress Bromus. 4 In competition plots, target Artemisia grown with Bromus were stunted relative to those grown with Elymus, despite equivalent above-ground biomass of the two grasses. Competition for nitrogen in spring and autumn, assessed with15N tracer, appears to be secondary to moisture availability in determining competitive outcomes. 5 Elymus physiology and function appear to play an important role in determining the composition of communities in Curlew Valley, by maintaining zones free of Bromus where Artemisia can recruit.
To describe the histopathologic features of Descemet's membrane (DM) obtained from Fuchs' endothelial corneal dystrophy (FECD) corneas undergoing Descemet's stripping with endothelial keratoplasty ...(DSEK) and to assess the presence of advanced glycation end products (AGEs) and their receptors in FECD endothelium and DM.
Prospective observational case series.
Five eyes of 5 patients undergoing DSEK for FECD and 4 normal control eyebank corneas.
Descemet's membrane and corneal endothelium from FECD patients undergoing DSEK were assessed with hematoxylin-eosin staining and immunohistochemistry for AGEs, receptor of AGEs (RAGE), and galectin 3 (AGE-R3).
Histopathologic abnormalities and presence of AGEs, RAGE, and AGE-R3 in DSEK specimens.
Histopathologic assessment of DSEK specimens from FECD patients disclosed thickening and nodularity of DM and loss of endothelial cells. Immunohistochemical staining of FECD DM for AGE, RAGE, and AGE-R3 showed an abundance of AGEs in the anterior portion of DM, mild positivity for RAGE, and moderate positivity for AGE-R3.
Tissue quality after DSEK is sufficient to allow detailed histopathologic analysis. The presence of AGEs, RAGE, and AGE-R3 in DM and corneal endothelium of FECD patients supports a link between accumulation of AGEs, oxidative stress, and corneal endothelial cell apoptosis in the pathogenesis of FECD.
To determine if postsurgical corneal interface abnormalities after deep lamellar endothelial keratoplasty (DLEK) cause increased light scattering or wavefront aberrations that may help to explain ...decreased best-corrected visual acuity in DLEK patients compared with penetrating keratoplasty (PK) patients.
Prospective comparative case series.
Clinically clear corneas of 4 eyes that had undergone DLEK surgery and 4 eyes that had PK were studied. Normal control data for light scattering was collected from 12 right eyes and 11 left eyes with normal corneas.
Corneal light scattering was measured with a scatterometer designed at the Johns Hopkins Applied Physics Laboratory, and wavefront analysis was performed using standard methods with a Hartmann-Shack wavefront sensor.
Corneal scattering measurements were normalized by taking the ratio of the subject's corneal light scattering to a reference material. A scattering index was calculated as the ratio of the normalized scattering for a given patient's cornea to the average scattering of normal corneas. Astigmatism and higher-order aberrations were analyzed using standard data output from wavefront analysis and Zernike polynomial decomposition.
The mean scattering index was significantly higher after DLEK (1.78+/-0.29, mean+/-standard deviation SD) than after PK (1.03+/-0.27; P = 0.043). The higher-order root mean square (RMS) wavefront error was significantly higher after PK (0.71+/-0.11 microm, mean+/-SD) than after DLEK (0.44+/-0.12 microm; P = 0.029). Zernike polynomial decomposition of the wavefront aberrations revealed that regular corneal astigmatism was the most important aberration component for both PK and DLEK, but the PK patients had significantly more regular astigmatism (1.7+/-0.45 diopters D, mean+/-SD) than did the DLEK patients (0.84+/-0.27 D; P = 0.029).
Our data quantitatively support subclinical corneal haze as an explanation for the limited visual acuity after DLEK as compared with PK. Intraoperative or postoperative modifications to reduce stromal haze after DLEK may result in better visual acuity outcomes.
To compare the gene expression profiles of normal human corneal endothelium with Fuchs' corneal endothelium, by using serial analysis of gene expression (SAGE).
Three pairs of normal human corneas ...were obtained from eye banks. Thirteen bisected Fuchs' corneal buttons were processed at the time of corneal transplantation. The endothelia of normal and Fuchs'-affected corneas were stripped, and total RNA was isolated. Serial analysis of gene expression (SAGE) was performed to identify and quantify gene transcripts. Genes over- and underexpressed by Fuchs' endothelium were limited to P < 0.01 by the method of Audic and Claverie.
A total of 19,136 tags were identified with 9,530 from normal and 9,606 from Fuchs' endothelium. The expression of 18 transcripts was upregulated, and 36 transcripts were downregulated in Fuchs' endothelium compared with normal tissue. Upregulated transcripts included serum amyloid A1 and A2, metallothionein, and apolipoprotein D. Of the downregulated transcripts, 26 matched known genes, 3 matched expressed sequence tags (ESTs), and 7 were unknown to current databases. One downregulated transcript involved a newly reported bicarbonate transporter. Decreased transcripts related to antioxidants and proteins conferring protection against toxic stress were noted in Fuchs' versus normal endothelium including nuclear ferritin, glutathione S-transferase-pi, and heat shock 70-kDa protein. Nine different SAGE tags matching mitochondrial sequences accounted for 25% of the ESTs that were decreased in Fuchs' endothelium.
SAGE analysis comparing normal to Fuchs' endothelium demonstrates diminished expression of mitochondrial, pump function, and antiapoptotic cell defense genes.
Population dynamics models are useful predictive tools in applied ecology, and especially toxicological risk assessment. Many models that are useful for capturing deterministic constant-parameter ...dynamics are inadequate for dealing with temporally variable life history parameter values typical of many anthropogenic disturbances, including those associated with toxicological insults. Using aphid-insecticide population data as an example, here we show that constant-parameter versions of commonly used population dynamics models (a matrix model and a simple differential equation model) do not adequately capture the population dynamics of aphids subjected to a selective pesticide. However, a simple modification of the differential equation model with time-varying mortality rates provides a highly accurate fit to aphid population data. Our results suggest that variable coefficient differential equation models with time-dependent parameters provide an accurate and simple means of assessing the effects of disturbances on populations in cases where the effects of disturbance vary significantly through time. We suggest that this approach has potential for a wide range of ecological applications.
Anaemia of prematurity will affect 90% of all very preterm infants, resulting in at least one red blood cell (RBC) transfusion. A significant proportion of preterm infants require multiple ...transfusions over the course of hospital admission. Growing evidence supports an association between transfusion exposure and adverse neonatal outcomes. In adults, transfusion‐associated sepsis, transfusion‐related acute lung injury and haemolytic reactions are the leading causes of transfusion‐related morbidity and mortality; however, these are seldom recognised in newborns. The association between transfusion and adverse outcomes remains inconclusive. However, the evidence from preclinical studies demonstrates that RBC products can directly modulate immune cell function, a pathway termed transfusion‐related immunomodulation (TRIM), which may provide a mechanism linking transfusion exposure with neonatal morbidities. Finally, we discuss the impact of TRIM on transfusion medicine, how we may address these issues and the emerging areas of research aimed at improving the safety of transfusions in this vulnerable population.
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Biological materials derived from the extracellular matrix (ECM) of tissues serve as scaffolds for rebuilding tissues and for improved wound healing. Cornea trauma represents a wound ...healing challenge as the default repair pathway can result in fibrosis and scar formation that limit vision. Effective treatments are needed to reduce inflammation, promote tissue repair, and retain the tissue’s native transparency and vision capacity. Tissue microparticles derived from cornea, cartilage and lymph nodes were processed and screened in vitro for their ability to reduce inflammation in ocular surface cells isolated from the cornea stroma, conjunctiva, and lacrimal gland. Addition of ECM particles to the media reduced expression of inflammatory genes and restored certain tear film protein production in vitro. Particles derived from lymph nodes were then applied to a rabbit lamellar keratectomy corneal injury model. Application of the tissue particles in a fibrin glue carrier decreased expression of inflammatory and fibrotic genes and scar formation as measured through imaging, histology and immunohistochemistry. In sum, immunomodulatory tissue microparticles may provide a new therapeutic tool for reducing inflammation in the cornea and ocular surface and promoting tissue repair.
Damaged cornea will result in scar tissue formation that impedes vision, and new therapies are needed to enhance wound healing in the cornea and to prevent fibrosis. We evaluated the effects of biological scaffolds derived extracellular matrix (ECM) during corneal wound healing. These ECM particles reduced inflammatory gene expression and restored tear film production in vitro, and reduced scar formation and fibrosis genes in the wounded cornea, when applied to in vivo lamellar keratectomy injury model. The immunomodulatory tissue microparticles may provide a new therapeutic tool for reducing inflammation in the cornea and ocular surface and promoting proper tissue repair.
Skin equivalents formed by keratinocytes cocultured with fibroblasts embedded in collagen lattices represent promising tools for mechanistic studies of skin physiology, for pharmacotoxicologic ...testing, and for the use as skin substitutes in wound treatment. Such cultures would be superior in defined media to avoid interference with components of serum or tissue extracts. Here we demonstrate that a defined medium (supplemented keratinocyte defined medium) supports epidermal morphogenesis in organotypic cocultures equally well as serum-containing medium (mixture of Ham’s F12 and Dulbecco’s modified Eagle’s medium), as documented by hallmarks of the epidermal phenotype studied by immunofluorescence and electron microscopy. In both cases regularly structured, orthokeratinized epithelia evolved with similar kinetics. Morphology in mixture of Ham’s F12 and Dulbecco’s modified Eagle’s medium was slightly hyperplastic, and keratins 1 and 10 synthesis less co-ordinated than in supplemented keratinocyte defined medium, but a consistently inverted sequence of expression of keratins 1 and 10 was found in either medium. The late differentiation markers filaggrin, involucrin, keratin 2e, and transglutaminase 1 corresponded in their typical distribution in upper suprabasal layers. Keratin 16 persisted under both conditions indicating the activated epidermal state. Keratinocyte proliferation was comparable in both media, whereas fibroblast multiplication and proliferation was delayed and reduced in supplemented keratinocyte defined medium. In both media, ultrastructural features of epidermal differentiation as well as reconstitution of a basement membrane occurred similarly. Immature lamellar bodies and cytoplasmatic vacuoles, however, indicated an impaired lipid metabolism in supplemented keratinocyte defined medium. Nevertheless, these defined organotypic cocultures provide a suitable basis for in vitro skin models to study molecular mechanisms of tissue homeostasis and for use in pharmacotoxicologic testing.
Scholars often consider the implied audience of Romans to have been a mixture of Jews and gentiles, albeit with a gentile majority. Other scholars challenge this thesis, however, and argue that the ...implied audience is exclusively gentile. Romans 1:13-14 is an important locus in this debate, but four points about these verses require further consideration. These are (1) the case of the elements Paul unites with the τὲ καί constructions in verse 14, (2) the variety of complements Paul gives ὀφειλέτης elsewhere, (3) the explanatory relationship of verse 14 to verse 13, and (4) the clearly personal focus of the language that appears with the τὲ καί constructions in verse 14. Duly considered, these points argue strongly for an exclusively gentile implied audience.
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