bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activin A Maintains Self-Renewal and Regulates Fibroblast Growth Factor, Wnt, and Bone Morphogenic Protein Pathways in Human Embryonic Stem Cells
Authors: Xiao Lei , Yuan Xuan , Sharkis Saul J. 
Published: February 2006

Abstract
Human embryonic stem cells (hESCs) self-renew indefinitely while maintaining pluripotency. The molecular mechanism underlying hESCs self-renewal and pluripotency is poorly understood. To identify the signaling pathway molecules that maintain the proliferation of hESCs, we performed a microarray analysis comparing an aneuploid H1 hESC line (named H1T) versus euploid H1 hESC line because the H1T hESC line demonstrates a self-renewal advantage while maintaining pluripotency. We find differential gene expression for the Nodal/Activin, fibroblast growth factor (FGF), Wnt, and Hedgehog (Hh) signaling pathways in the H1T line, which implicates each of these molecules in maintaining the undifferentiated state, whereas the bone morphogenic protein (BMP) and Notch pathways could promote hESCs differentiation. Experimentally, we find that Activin A is necessary and sufficient for the maintenance of self-renewal and pluripotency of hESCs and supports long-term feeder and serum-free growth of hESCs. We show that Activin A induces the expression of Oct4, Nanog, Nodal, Wnt3, basic FGF, and FGF8 and suppresses the BMP signal. Our data indicates Activin A as a key regulator in maintenance of the stemness in hESCs. This finding will help elucidate the complex signaling network that maintains the hESC phenotype and function.
Cellular Memory and Hematopoietic Stem Cell Aging
Authors: Kamminga Leonie M. , de Haan Gerald 
Published: February 2006

AbstractHematopoietic stem cells (HSCs) balance self-renewal and differentiation in order to sustain lifelong blood production and simultaneously maintain the HSC pool. However, there is clear evidence that HSCs are subject to quantitative and qualitative exhaustion. In this review, we briefly discuss several known aspects of the stem cell aging process, including DNA damage, telomere shortening, and oxidative stress. Besides these known players, there is increasing evidence that higher order chromatin structure, largely defined by the histone code and affecting transcriptional activity, is important. A model is suggested which describes how epigenetic regulation of gene transcription by modulation of the chromatin structure in stem cells can account for regulation of the aging program.
Improved Safety of Hematopoietic Transplantation with Monkey Embryonic Stem Cells in the Allogeneic Setting
Authors: Shibata Hiroaki , Ageyama Naohide , Tanaka Yujiro , Kishi Yukiko , Sasaki Kyoko , Nakamura Shinichiro , Muramatsu Shin-ichi , Hayashi Satoshi , Kitano Yoshihiro , Terao Keiji , Hanazono Yutaka 
Published: February 2006

Abstract
Cynomolgus monkey embryonic stem cell (cyESC)-derived in vivo hematopoiesis was examined in an allogeneic transplantation model. cyESCs were induced to differentiate into the putative hematopoietic precursors in vitro, and the cells were transplanted into the fetal cynomolgus liver at approximately the end of the first trimester (n = 3). Although cyESC-derived hematopoietic colony-forming cells were detected in the newborns (4.1%–4.7%), a teratoma developed in all newborns. The risk of tumor formation was high in this allogeneic transplantation model, given that tumors were hardly observed in immunodeficient mice or fetal sheep that had been xeno-transplanted with the same cyESC derivatives. It turned out that the cyESC-derived donor cells included a residual undifferentiated fraction positive for stage-specific embryonic antigen (SSEA)-4 (38.2% ± 10.3%) despite the rigorous differentiation culture. When an SSEA-4-negative fraction was transplanted (n = 6), the teratoma was no longer observed, whereas the cyESC-derived hematopoietic engraftment was unperturbed (2.3%–5.0%). SSEA-4 is therefore a clinically relevant pluripotency marker of primate embryonic stem cells (ESCs). Purging pluripotent cells with this surface marker would be a promising method of producing clinical progenitor cell preparations using human ESCs.
Identification of Label-Retaining Cells in Mouse Endometrium
Authors: Chan Rachel W.S. , Gargett Caroline E. 
Published: February 2006

Abstract
Human and mouse endometrium (lining of the uterus) undergo cycles of growth and regression as part of each reproductive cycle. A well-known method to identify somatic stem/progenitor cells and their location in the stem cell niche is the label-retaining cell (LRC) approach. We hypothesized that mouse endometrium contains small populations of both epithelial and stromal somatic stem/progenitor cells that may be detected by the LRC technique. The overall objective of this study was to identify and quantify LRCs in mouse endometrium, to determine their location, and to identify their niche in this highly regenerative tissue. Endometrium was labeled for 3 days with bromodeoxyuridine (BrdU) in postnatal day 3 (P3) mice prior to gland development and prepubertal (P19) mice after glands had formed, followed by chase periods of up to 12 weeks. After an 8-week chase, 3% of epithelial nuclei immunostained with BrdU antibody and were considered epithelial LRCs. These were primarily located in the luminal epithelium. Epithelial LRCs did not express estrogen receptor-α (ER-α). Stromal LRCs (6%) were found adjacent to luminal epithelium, at the endometrial-myometrial junction, and near blood vessels after a 12-week chase. Stromal LRCs were stem cell antigen-1, CD45−, and some (16%) expressed ER-α, indicating their capacity to respond to estrogen and transmit paracrine signals to epithelial cells for endometrial epithelium regeneration. Both epithelial LRCs and some stromal LRCs, mainly located at the endometrial-myometrial junction, were recruited into the cell cycle after estrogen-stimulated endometrial regeneration, indicating a functional response to proliferative signals. This study has demonstrated for the first time the presence of both epithelial and stromal LRCs in mouse endometrium, suggesting that these stem-like cells may be responsible for endometrial regeneration.
Differential expression of mRNAs encoding the putative inhibin co-receptor (betaglycan) and activin type-I and type-II receptors in preovulatory and prehierarchical follicles of the laying hen ovary
Authors: Lovell T M , Knight P G , Gladwell R T 
Published: February 2006

Ovarian follicle development is primarily regulated by an interplay between the pituitary gonadotrophins, LH and FSH, and ovary-derived steroids. Increasing evidence implicates regulatory roles of transforming growth factor-β (TGFβ) superfamily members, including inhibins and activins. The aim of this study was to identify the expression of mRNAs encoding key receptors of the inhibin/activin system in ovarian follicles ranging from 4 mm in diameter to the dominant F1 follicle (~40 mm).
Ovaries were collected (n=16) from mid-sequence hens maintained on a long-day photoschedule (16 h of light:8 h of darkness). All follicles removed were dissected into individual granulosa and thecal layers. RNA was extracted and cDNA synthesized. Real-time quantitative PCR was used to quantify the expression of mRNA encoding betaglycan, activin receptor (ActR) subtypes (type-I, -IIA and -IIB) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH); receptor expression data were normalized to GAPDH expression. Detectable levels of ActRI, -IIA and -IIB and the inhibin co-receptor (betaglycan) expression were found in all granulosa and thecal layers analysed. Granulosa ActRI mRNA peaked (P < 0.05) in 8–9.9 mm follicles, whereas ActRIIA rose significantly from 6–7.9 mm to 8–9.9 mm, before falling to F3/2; levels then rose sharply (3-fold) to F1 levels. Granulosa betaglycan mRNA expression rose 3-fold from 4–5.9 mm to 8–9.9 mm, before falling 4-fold to F3/2; levels then rose sharply (4-fold) to F1 levels. ActRIIB levels did not vary significantly during follicular development. Thecal ActRI mRNA expression was similar from 4–7.9 mm then decreased significantly to a nadir at the F4 position, before increasing 2-fold to the F1 (P < 0.05). Although thecal ActRIIB and -IIA expression did not vary significantly from 4 mm to F3, ActRIIB expression increased significantly (2-fold) from F3 to F1 and ActRIIA increased 2-fold from F2 to F1 (P < 0.05). Thecal betaglycan fell to a nadir at F6 after follicle selection; levels then increased significantly to F2, before falling ~50% in the F1.
In all follicles studied expression of betaglycan and ActRI (granulosa: r=0.65, P < 0.001, n=144/group; theca: r=0.49, P < 0.001, n=144/group) was well correlated. No significant correlations were identified between betaglycan and ActRIIA or -IIB. Considering all follicles analysed, granulosa mRNA expression of betaglycan, ActRI, ActRIIA and ActRIIB were all significantly lower than in corresponding thecal tissue (betaglycan, 11.4-fold; ActRIIB, 5.1-fold; ActRI, 3.8-fold; ActRIIA, 2.8-fold). The co-localization of type-I and -II activin receptors and betaglycan on granulosa and thecal cells are consistent with a local auto/paracrine role of inhibins and activins in modulating ovarian follicle development, selection and progression in the domestic fowl.
Upflow Reactors for Riparian Zone Denitrification
Authors: van Driel Peter W. , Robertson William D. , Merkley L. Craig 
Published: February 2006

ABSTRACTWe used permeable reactive subsurface barriers consisting of a C source (wood particles), with very high hydraulic conductivities (∼0.1–1 cm s−1), to provide high rates of riparian zone NO3–N removal at two field sites in an agricultural area of southwestern Ontario. At one site, a 0.73‐m3 reactor containing fine wood particles was monitored for a 20‐mo period and achieved a 33% reduction in mean influent NO3–N concentration of 11.5 mg L−1 and a mean removal rate of 4.5 mg L−1 d−1 (0.7 g m−2 d−1). At the second site, four smaller reactors (0.21 m3 each), two containing fine wood particles and two containing coarse wood particles, were monitored for a 4‐mo period and were successful in attenuating mean influent NO3–N concentrations of 23.7 to 35.1 mg L−1 by 41 to 63%. Mean reaction rates for the two coarse‐particle reactors (3.2 and 7.8 mg L−1 d−1, or 1.5 and 3.4 g m−2 d−1) were not significantly different (p > 0.2) than the rates observed in the two fine‐particle reactors (5.0 and 9.9 mg L−1 d−1, or 1.8–3.5 g m−2 d−1). A two‐dimensional ground water flow model is used to illustrate how permeable reactive barriers such as these can be used to redirect ground water flow within riparian zones, potentially augmenting NO3− removal in this environment.
Predicting Soil Erosion for Alternative Land Uses
Authors: Wang Erda , Xin Chang , Williams Jimmy R. , Xu Cheng 
Published: February 2006

ABSTRACTThe APEX (Agricultural Policy–Environmental eXtender) model developed in the United States was calibrated for northwestern China's conditions. The model was then used to investigate soil erosion effects associated with alternative land uses at the ZFG (Zi‐Fang‐Gully) watershed in northwestern China. The results indicated that the APEX model could be calibrated reasonably well (±15% errors) to fit those areas with >50% slope within the watershed. Factors being considered during calibration include runoff, RUSLE (Revised Universal Soil Loss Equation) slope length and steepness factor, channel capacity flow rate, floodplain saturated hydraulic conductivity, and RUSLE C factor coefficient. No changes were made in the APEX computer code. Predictions suggest that reforestation is the best practice among the eight alternative land uses (the status quo, all grass, all grain, all grazing, all forest, half tree and half grass, 70% tree and 30% grain, and construction of a reservoir) for control of water runoff and soil erosion. Construction of a reservoir is the most effective strategy for controlling sediment yield although it does nothing to control upland erosion. For every 1 Mg of crop yield, 11 Mg of soil were lost during the 30‐yr simulation period, suggesting that expanding land use for food production should not be encouraged on the ZFG watershed. Grass species are less effective than trees in controlling runoff and erosion on steep slopes because trees generally have deeper and more stable root systems.
Increased Wind Erosion from Forest Wildfire: Implications for Contaminant‐Related Risks
Authors: Whicker Jeffrey J. , Pinder John E. , Breshears David D. 
Published: February 2006

ABSTRACTAssessments of contaminant‐related human and ecological risk require estimation of transport rates, but few data exist on wind‐driven transport rates in nonagricultural systems, particularly in response to ecosystem disturbances such as forest wildfire and also relative to water‐driven transport. The Cerro Grande wildfire in May of 2000 burned across ponderosa pine (Pinus ponderosa Douglas ex P.&C. Lawson var. scopulorum Englem.) forest within Los Alamos National Laboratory in northern New Mexico, where contaminant transport and associated post‐fire inhalation risks are of concern. In response, the objectives of this study were to measure and compare wind‐driven horizontal and vertical dust fluxes, metrics of transport related to wind erosion, for 3 yr for sites differentially affected by the Cerro Grande wildfire: unburned, moderately burned (fire mostly confined to ground vegetation), and severely burned (crown fire). Wind‐driven dust flux was significantly greater in both types of burned areas relative to unburned areas, by more than one order of magnitude initially and by two to three times 1 yr after the fire. Unexpectedly, the elevated dust fluxes did not decrease during the second and third years in burned areas, apparently because ongoing drought delayed post‐fire recovery. Our estimates enable assessment of amplification in contaminant‐related risks following a major type of disturbance‐wildfire, which is expected to increase in intensity and frequency due to climate change. More generally, our results highlight the importance of considering wind‐ as well as water‐driven transport and erosion, particularly following disturbance, for ecosystem biogeochemistry in general and human and ecological risk assessment in particular.
Spatial Analysis of Land Use Impact on Ground Water Nitrate Concentrations
Authors: Benson Victoria S. , VanLeeuwen John A. , Sanchez Javier , Dohoo Ian R. , Somers George H. 
Published: February 2006

ABSTRACTIn spatial analyses of causes or health effects of environmental pollutants, small units of analyses are usually preferred for internal environmental homogeneity reasons but can only be done when fine resolution data are available for most units. Objectives of this study were to determine which land use practices were spatially associated with ground water nitrate concentrations across Prince Edward Island (PEI), Canada, and which spatial aggregation is the preferred unit of analyses. Nitrate concentrations were determined for 4855 samples from private wells. Validated field‐by‐field land use data were available. Average nitrate concentration and percentage of area for the 14 major land use categories in PEI were determined for each of three spatial aggregations: watersheds based on topography and hydrology; freeform polygon boundaries based on similar neighboring nitrate concentrations; and 500‐m buffer zones around each well. Results showed that the percentages of potato, grain, and hay coverage were positive predictors of ground water nitrate concentrations. Percentage of blueberry was a marginally significant negative predictor in the watershed and freeform polygon models, and percentage of residential coverage was a positive predictor in the freeform polygon and buffer zone models. Spatial autocorrelation was present in the freeform polygon and buffer zone models even after land use was taken into account. In conclusion, analyses based on watersheds produced the best predictive model with the percentages of land cover of potato, hay, and grain being significantly associated with ground water nitrate concentrations, and the percentages of blueberry, clear‐cut woodland, and other agriculture being marginally significant.
Wildfire Effects on Soil Nutrients and Leaching in a Tahoe Basin Watershed
Authors: Murphy J. D. , Johnson D. W. , Miller W. W. , Walker R. F. , Carroll E. F. , Blank R. R. 
Published: February 2006

ABSTRACTA wildfire burned through a previously sampled research site, allowing pre‐ and post‐burn measurements of the forest floor, soils, and soil leaching near Lake Tahoe, Nevada. Fire and post‐fire erosion caused large and statistically significant (P ≤ 0.05) losses of C, N, P, S, Ca, and Mg from the forest floor. There were no statistically significant effects on mineral soils aside from a decrease in total N in the surface (A11) horizon, an increase in pH in the A11 horizon, and increases in water‐extractable SO42− in the A11 and A12 horizons. Burning caused consistent but nonsignificant increases in exchangeable Ca2+ in most horizons, but no consistent or statistically significant effects on exchangeable K+ or Mg2+, or on Bray‐, bicarbonate‐, or water‐extractable P concentrations. Before the burn, there were no significant differences in leaching, but during the first winter after the fire, soil solution concentrations of NH4+, NO3−, ortho‐P, and (especially) SO42− were elevated in the burned area, and resin lysimeters showed significant increases in the leaching of NH4+ and mineral N. The leaching losses of mineral N were much smaller than the losses from the forest floor and A11 horizons, however. We conclude that the major short‐term effects of wildfire were on leaching whereas the major long‐term effect was the loss of N from the forest floor and soil during the fire.
Bedding and Within‐Pen Location Effects on Feedlot Pen Runoff Quality Using a Rainfall Simulator
Authors: Miller Jim J. , Olson Edith C. S. , Chanasyk David S. , Beasley Bruce W. , Yanke L. Jay , Larney Francis J. , McAllister Tim A. , Olson Barry M. , Selinger L. Brent 
Published: February 2006

ABSTRACTSoluble salts, nutrients, and pathogenic bacteria in feedlot‐pen runoff have the potential to cause pollution of the environment. A 2‐yr study (1998–1999) was conducted at a beef cattle (Bos taurus) feedlot in southern Alberta, Canada, to determine the effect of bedding material [barley (Hordeum vulgare L.) straw versus wood chips] and within‐pen location on the chemical and bacterial properties of pen‐floor runoff. Runoff was generated with a portable rainfall simulator and analyzed for chemical content (nitrogen [N], phosphorus [P], soluble salts, electrical conductivity [EC], sodium adsorption ratio [SAR], dissolved oxygen [DO], and pH) and populations of three groups of bacteria (Escherichia coli, total coliforms, total aerobic heterotrophs at 27°C) in 1998 and 1999. Bedding had a significant (P ≤ 0.05) effect on NH4–N concentration and load in 1999, SO4 load in 1998, SO4 concentration and load in 1999, and total coliforms in both years; where these three variables were higher in wood than straw pens. Location had a significant effect on EC and concentrations of total Kjeldahl nitrogen (TKN), Na, K, SO4, and Cl in 1998, and total coliforms in both years. These seven variables were higher at the bedding pack than pen floor location, indicating that bedding packs were major reservoirs of TKN, soluble salts, and total coliforms. Significantly higher dissolved reactive phosphorus (DRP), total P, and NH4–N concentrations and loads at the bedding pack location in wood pens in 1998, and a similar trend for TKN concentration in 1999, indicated that this bedding–location treatment was a greater source of nutrients to runoff than the other three bedding–location treatments. Bedding, location, and their interaction may therefore be a potential tool to manage nutrients, soluble salts, and bacteria in feedlot runoff.
Matrix metalloproteinase-9 activity in the cerebrospinal fluid and serum of dogs with acute spinal cord trauma from intervertebral disk disease
Authors: Levine Jonathan M. , Ruaux Craig G. , Bergman Robert L. , Coates Joan R. , Steiner Jörg M. , Williams David A. 
Published: February 2006

Abstract
Objective—To detect matrix metalloproteinase (MMP)-9 in serum and CSF and determine relationships between MMP activity and severity of disease, duration of clinical signs, and duration of hospitalization in dogs with acute intervertebral disk disease (IVDD).
Animals—35 dogs with acute IVDD and 8 clinically normal control dogs.
Procedure—CSF and serum were collected from affected and control dogs. Zymography was used to detect MMP-9.
Results—Activity of MMP-9 in CSF was detected in 6 of 35 dogs with IVDD; activity was significantly more common in dogs with duration of signs < 24 hours. Paraplegic dogs were more likely to have MMP-9 activity in the CSF than non-paraplegic dogs. No significant difference in hospitalization time was detected in dogs with IVDD between those with and without activity of MMP-9 in the CSF. Serum MMP-9 was detected more frequently in dogs with IVDD than in control dogs.
Conclusions and Clinical Relevance—Data were consistent with results of experimental rodent spinal cord injury studies that indicate that MMP-9 is expressed early during secondary injury.
Evaluation of concentration of voriconazole in aqueous humor after topical and oral administration in horses
Authors: Clode Alison B. , Davis Jennifer L. , Salmon Jacklyn , Michau Tammy Miller , Gilger Brian C. 
Published: February 2006

Abstract
Objective—To determine penetration of topically and orally administered voriconazole into ocular tissues and evaluate concentrations of the drug in blood and signs of toxicosis after topical application in horses.
Animals—11 healthy adult horses.
Procedure—Each eye in 6 horses was treated with a single concentration (0.5%, 1.0%, or 3.0%) of a topically administered voriconazole solution every 4 hours for 7 doses. Anterior chamber paracentesis was performed and plasma samples were collected after application of the final dose. Voriconazole concentrations in aqueous humor (AH) and plasma were measured via high-performance liquid chromatography. Five horses received a single orally administered dose of voriconazole (4 mg/kg); anterior chamber paracentesis was performed, and voriconazole concentrations in AH were measured.
Results—Mean ± SD voriconazole concentrations in AH after topical administration of 0.5%, 1.0%, and 3.0% solutions (n = 4 eyes for each concentration) were 1.43 ± 0.37 μg/mL, 2.35 ± 0.78 μg/mL, and 2.40 ± 0.29 μg/mL, respectively. The 1.0% and 3.0% solutions resulted in significantly higher AH concentrations than the 0.5% solution, and only the 3.0% solution induced signs of ocular toxicosis. Voriconazole was detected in the plasma for 1 hour after the final topically administered dose of all solutions. Mean ± SD voriconazole concentration in AH after a single orally administered dose was 0.86 ± 0.22 μg/mL.
Conclusions and Clinical Relevance—Results indicated that voriconazole effectively penetrated the cornea in clinically normal eyes and reached detectable concentrations in the AH after topical administration. The drug also penetrated noninflamed equine eyes after oral administration. Low plasma concentrations of voriconazole were detected after topical administration.