bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reprogrammed Mouse Fibroblasts Differentiate into Cells of the Cardiovascular and Hematopoietic Lineages
Authors: Schenke-Layland Katja , Rhodes Katrin E. , Angelis Ekaterini , Butylkova Yekaterina , Heydarkhan-Hagvall Sepideh , Gekas Christos , Zhang Rui , Goldhaber Joshua I. , Mikkola Hanna K. , Plath Kathrin , MacLellan W. Robb 
Published: May 2008

Abstract
Forced expression of the four transcription factors Oct4, Sox2, c-Myc, and Klf4 is sufficient to confer a pluripotent state upon the murine fibroblast genome, generating induced pluripotent stem (iPS) cells. Although the differentiation potential of these cells is thought to be equivalent to that of embryonic stem (ES) cells, it has not been rigorously determined. In this study, we sought to identify the capacity of iPS cells to differentiate into Flk1-positive progenitors and their mesodermal progeny, including cells of the cardiovascular and hematopoietic lineages. Immunostaining of tissues from iPS cell-derived chimeric mice demonstrated that iPS cells could contribute in vivo to cardiomyocytes, smooth muscle cells, endothelial cells, and hematopoietic cells. To compare the in vitro differentiation potential of murine ES and iPS cells, we either induced embryoid body (EB) formation of each cell type or cultured the cells on collagen type IV (ColIV), an extracellular matrix protein that had been reported to direct murine ES cell differentiation to mesodermal lineages. EB formation and exposure to ColIV both induced iPS cell differentiation into cells that expressed cardiovascular and hematopoietic markers. To determine whether ColIV-differentiated iPS cells contained a progenitor cell with cardiovascular and hematopoietic differentiation potential, Flk1-positive cells were isolated by magnetic cell sorting and exposed to specific differentiation conditions, which induced differentiation into functional cardiomyocytes, smooth muscle cells, endothelial cells, and hematopoietic cells. Our data demonstrate that murine iPS cells, like ES cells, can differentiate into cells of the cardiovascular and hematopoietic lineages and therefore may represent a valuable cell source for applications in regenerative medicine.
Disclosure of potential conflicts of interest is found at the end of this article.
Implementing Socket Seal Surgery as a Socket Preservation Technique for Pontic Site Development: Surgical Steps Revisited – A Report of Two Cases
Authors: Landsberg Cobi J. 
Published: May 2008

Background: Tooth removal is always followed by the loss of vital soft and hard tissues. When occurring in the anterior region of the maxilla, the resulting ridge deformation may cause severe functional and esthetic problems. Diverse soft and hard tissue regenerative procedures have been developed for correcting ridge defects with the aim of establishing functional and esthetically pleasing pontic or implant restoration sites. However, these technically demanding procedures may be regarded as non‐predictable in the hands of most clinicians. To reduce the need for restoring challenging ridge defects, an alternative exists in the form of a simple, minimally invasive socket‐preservation procedure immediately following tooth extraction known as socket seal surgery. This article describes the currently improved surgical steps to be implemented with the objective of achieving a functional and esthetically acceptable pontic site.Methods: Immediately following tooth extraction, the socket bony walls are debrided and decorticated, and the soft tissue walls are deepithelialized by a coarse round diamond bur. The socket is filled with particles of a slowly resorbing bone substitute material except for 2 to 3 mm coronally. A cylindrically shaped soft tissue graft that matches the socket orifice contours is harvested from the palatal mucosa and placed atop the bone graft. The soft tissue graft is usually stabilized with six to eight simple interrupted 6‐0 monofilament polyamide or 7‐0 polypropylene sutures or, when the case allows, by a broad‐based pontic restoration that is placed at a minimal distance from the graft.Results: Two cases, each representing a different technique for stabilizing the soft tissue graft, demonstrate successful graft survival. Clinically and radiographically, successful regeneration of the ridge's hard and soft tissues, including the ability to develop functional and esthetically acceptable pontic sites, was demonstrated.Conclusions: Socket seal surgery is an efficacious procedure for ridge preservation and is effective in providing the necessary conditions for the development of functional and esthetic pontic sites.
Thyroid Hormones May Influence Cortical Bone Healing Around Titanium Implants: A Histometric Study in Rats
Authors: Feitosa Daniela da Silva , Bezerra Beatriz de Brito , Ambrosano Gláucia Maria Bovi , Nociti Francisco Humberto , Casati Márcio Zaffalon , Sallum Enilson Antônio , de Toledo Sérgio 
Published: May 2008

Background: The aim of the present study was to evaluate, by histometric analysis, the influence of the thyroid hormones, triiodothyronine (T3) and thyroxine (T4), on bone healing around titanium implants inserted in rat tibiae.Methods: Forty‐two male Wistar rats were randomly assigned to the experimental groups: G1 = healthy animals (control; N = 15); G2 = hypothyroidism (N = 13); and G3 = hyperthyroidism (N = 14). Once alterations were confirmed by total serum levels of T3 and T4, one screw‐shaped titanium implant was placed in the rat tibiae. Sixty days later, the animals were sacrificed, and undecalcified sections were obtained. Bone‐to‐implant contact (BIC), bone area within the limits of the implant threads, and bone density in a 500‐μm‐wide zone lateral to the implant were obtained separately for the cortical (zone A) and cancellous (zone B) bone regions.Results: Intergroup analysis demonstrated that thyroid hormones may significantly affect cortical bone healing around titanium implants. Hyperthyroidism significantly increased the area of newly formed bone in zone A (P <0.05), whereas hypothyroidism significantly decreased the area of newly formed bone and bone density around the implant in zone A (P <0.05) compared to the healthy group. In addition, hyperthyroidism significantly increased BIC extension in zone A compared to hypothyroidism (P <0.05).Conclusion: Thyroid hormones may influence the healing process in the cortical bone around titanium implants placed in rats, whereas cancellous bone seems to be less sensitive to changes in T3 and T4 serum levels.
Disease Progression in Periodontally Healthy and Maintenance Subjects
Authors: Teles R.P. , Patel M. , Socransky S.S. , Haffajee A.D. 
Published: May 2008

Background: The aim of this study was to determine whether the rate of attachment loss in periodontally healthy subjects in a prevention regimen would differ from the rate of disease progression in periodontitis subjects enrolled in a maintenance program.Methods: Fifty‐five periodontally healthy subjects and 57 periodontitis subjects were clinically and microbiologically monitored at baseline and at 1, 2, and 3 years. Clinical parameters measured at six sites per tooth included bleeding on probing, visible plaque, probing depth, and attachment level. Subgingival plaque samples were taken from the mesio‐buccal aspect of every tooth and were analyzed for the levels of 40 bacterial species using checkerboard DNA‐DNA hybridization. The significance of differences over time in the clinical parameters was determined using repeated‐measures analysis of variance, whereas the significance of differences between groups was determined using the unpaired t test. The Mann‐Whitney test was used for microbial analyses, and P values were adjusted for multiple comparisons.Results: Mean clinical parameters improved for both groups over time. By the end of the study, 4% of the sites in maintenance subjects lost ≥2 mm of attachment, whereas in the prophylaxis subjects only 1% of the sites lost ≥2 mm of attachment. Maintenance subjects lost attachment primarily at shallow buccal and lingual sites. The maintenance subjects harbored significantly higher levels of most test species throughout the study. The maintenance program did not reduce the levels of red complex species to those typical of healthy subjects.Conclusions: Treated periodontitis subjects under maintenance displayed more rapid attachment loss than periodontally healthy subjects in a preventive regimen. The greater propensity to disease progression may be related to an elevated exposure to periodontal pathogens.
Using Heat to Characterize Streambed Water Flux Variability in Four Stream Reaches
Authors: Essaid Hedeff I. , Zamora Celia M. , McCarthy Kathleen A. , Vogel Jason R. , Wilson John T. 
Published: May 2008

AbstractEstimates of streambed water flux are needed for the interpretation of streambed chemistry and reactions. Continuous temperature and head monitoring in stream reaches within four agricultural watersheds (Leary Weber Ditch, IN; Maple Creek, NE; DR2 Drain, WA; and Merced River, CA) allowed heat to be used as a tracer to study the temporal and spatial variability of fluxes through the streambed. Synoptic methods (seepage meter and differential discharge measurements) were compared with estimates obtained by using heat as a tracer. Water flux was estimated by modeling one‐dimensional vertical flow of water and heat using the model VS2DH. Flux was influenced by physical heterogeneity of the stream channel and temporal variability in stream and ground‐water levels. During most of the study period (April–December 2004), flux was upward through the streambeds. At the IN, NE, and CA sites, high‐stage events resulted in rapid reversal of flow direction inducing short‐term surface‐water flow into the streambed. During late summer at the IN site, regional ground‐water levels dropped, leading to surface‐water loss to ground water that resulted in drying of the ditch. Synoptic measurements of flux generally supported the model flux estimates. Water flow through the streambed was roughly an order of magnitude larger in the humid basins (IN and NE) than in the arid basins (WA and CA). Downward flux, in response to sudden high streamflows, and seasonal variability in flux was most pronounced in the humid basins and in high conductivity zones in the streambed.
Nitrogen Fluxes through Unsaturated Zones in Five Agricultural Settings across the United States
Authors: Green Christopher T. , Fisher Lawrence H. , Bekins Barbara A. 
Published: May 2008

AbstractThe main physical and chemical controls on nitrogen (N) fluxes between the root zone and the water table were determined for agricultural sites in California, Indiana, Maryland, Nebraska, and Washington from 2004 to 2005. Sites included irrigated and nonirrigated fields; soil textures ranging from clay to sand; crops including corn, soybeans, almonds, and pasture; and unsaturated zone thicknesses ranging from 1 to 22 m. Chemical analyses of water from lysimeters and shallow wells indicate that advective transport of nitrate is the dominant process affecting the flux of N below the root zone. Vertical profiles of (i) nitrogen species, (ii) stable isotopes of nitrogen and oxygen, and (iii) oxygen, N, and argon in unsaturated zone air and correlations between N and other agricultural chemicals indicate that reactions do not greatly affect N concentrations between the root zone and the capillary fringe. As a result, physical factors, such as N application rate, water inputs, and evapotranspiration, control the differences in concentrations among the sites. Concentrations of N in shallow lysimeters exhibit seasonal variation, whereas concentrations in lysimeters deeper than a few meters are relatively stable. Based on concentration and recharge estimates, fluxes of N through the deep unsaturated zone range from 7 to 99 kg ha−1yr−1Vertical fluxes of N in ground water are lower due to spatial and historical changes in N inputs. High N fluxes are associated with coarse sediments and high N application rates.
Pesticides in Rain in Four Agricultural Watersheds in the United States
Authors: Vogel Jason R. , Majewski Michael S. , Capel Paul D. 
Published: May 2008

AbstractRainfall samples were collected during the 2003 and 2004 growing seasons at four agricultural locales across the USA in Maryland, Indiana, Nebraska, and California. The samples were analyzed for 21 insecticides, 18 herbicides, three fungicides, and 40 pesticide degradates. Data from all sites combined show that 7 of the 10 most frequently detected pesticides were herbicides, with atrazine (70%) and metolachlor (83%) detected at every site. Dacthal, acetochlor, simazine, alachlor, and pendimethalin were detected in more than 50% of the samples. Chlorpyrifos, carbaryl, and diazinon were the only insecticides among the 10 most frequently detected compounds. Of the remaining pesticide parent compounds, 18 were detected in fewer than 30% of the samples, and 13 were not detected. The most frequently detected degradates were deethylatrazine; the oxygen analogs (OAs) of the organophosphorus insecticides chlorpyrifos, diazinon, and malathion; and 1‐napthol (degradate of carbaryl). Deethylatrazine was detected in nearly 70% of the samples collected in Maryland, Indiana, and Nebraska but was detected only once in California. The OAs of chlorpyrifos and diazinon were detected primarily in California. Degradates of the acetanilide herbicides were rarely detected in rain, indicating that they are not formed in the atmosphere or readily volatilized from soils. Herbicides accounted for 91 to 98% of the total pesticide mass deposited by rain except in California, where insecticides accounted for 61% in 2004. The mass of pesticides deposited by rainfall was estimated to be less than 2% of the total applied in these agricultural areas.
Extractability of Elements in Sugar Maple Xylem along a Gradient of Soil Acidity
Authors: Bilodeau Gauthier Simon , Houle Daniel , Gagnon Christian , Côté Benoît , Messier Christian 
Published: May 2008

AbstractDendrochemistry has been used for the historical dating of pollution. Its reliability is questionable due primarily to the radial mobility of elements in sapwood. In the present study, the extractability of seven elements was characterized to assess their suitability for the monitoring of environmental conditions. Nine mature sugar maple trees (Acer saccharum Marsh.), a wide‐ranging species in eastern North America that has suffered decline in past decades, were sampled in three Quebec watersheds along a soil acidity gradient. Five‐year groups of annual tree rings were treated by sequential chemical extractions using extractants of varying strength (deionized H2O, 0.05 M HCl, and concentrated HNO3) to selectively solubilize the elements into three fractions (water‐soluble, acid‐soluble, and residual). Monovalent K; divalent Ba, Ca, Cd, Mg, Mn; and trivalent Al cations were found mostly in the water‐soluble, acid‐soluble, and residual fractions, respectively. Forms more likely to be mobile within the tree (water‐soluble and acid‐soluble) do not seem to be suitable for temporal monitoring because of potential lateral redistribution in sapwood rings. However, certain elements (Cd, Mn) were responsive to current soil acidity and could be used in spatial variation monitoring. Extractability of Al varied according to soil acidity; at less acidic sites, up to 90% of Al was contained in the residual form, whereas on very acidic soils, as much as 45% was found in the water‐soluble and acid‐soluble fractions. Sequential extractions can be useful for determining specific forms of metals as key indicators of soil acidification.
Variations in Pesticide Leaching Related to Land Use, Pesticide Properties, and Unsaturated Zone Thickness
Authors: Webb Richard M. T. , Wieczorek Michael E. , Nolan Bernard T. , Hancock Tracy C. , Sandstrom Mark W. , Barbash Jack E. , Bayless E. Randall , Healy Richard W. , Linard Joshua 
Published: May 2008

AbstractPesticide leaching through variably thick soils beneath agricultural fields in Morgan Creek, Maryland was simulated for water years 1995 to 2004 using LEACHM (Leaching Estimation and Chemistry Model). Fifteen individual models were constructed to simulate five depths and three crop rotations with associated pesticide applications. Unsaturated zone thickness averaged 4.7 m but reached a maximum of 18.7 m. Average annual recharge to ground water decreased from 15.9 to 11.1 cm as the unsaturated zone increased in thickness from 1 to 10 m. These point estimates of recharge are at the lower end of previously published values, which used methods that integrate over larger areas capturing focused recharge in the numerous detention ponds in the watershed. The total amount of applied and leached masses for five parent pesticide compounds and seven metabolites were estimated for the 32‐km2 Morgan Creek watershed by associating each hectare to the closest one‐dimensional model analog of model depth and crop rotation scenario as determined from land‐use surveys. LEACHM parameters were set such that branched, serial, first‐order decay of pesticides and metabolites was realistically simulated. Leaching is predicted to be greatest for shallow soils and for persistent compounds with low sorptivity. Based on simulation results, percent parent compounds leached within the watershed can be described by a regression model of the form e−depth (a ln t½−b ln KOC) where t1/2 is the degradation half‐life in aerobic soils, KOC is the organic carbon normalized sorption coefficient, and a and b are fitted coefficients (R2 = 0.86, p value = 7 × 10−9).
Antibiotic Losses from Unprotected Manure Stockpiles
Authors: Dolliver Holly A.S. , Gupta Satish C. 
Published: May 2008

AbstractManure management is a major concern in livestock production systems. Although historically the primary concerns have been nutrients and pathogens, manure is also a source of emerging contaminants, such as antibiotics, to the environment. There is a growing concern that antibiotics in manure are reaching surface and ground waters and contributing to the development and spread of antibiotic resistance in the environment. One such pathway is through leaching and runoff from manure stockpiles. In this study, we quantified chlortetracycline, monensin, and tylosin losses in runoff from beef manure stockpiles during two separate but consecutive experiments representing different weather conditions (i.e., temperature and precipitation amount and form). Concentrations of chlortetracycline, monensin, and tylosin in runoff were positively correlated with initial concentrations of antibiotics in manure. The highest concentrations of chlortetracycline, monensin, and tylosin in runoff were 210, 3175, and 2544 μg L−1, respectively. Relative antibiotic losses were primarily a function of water losses. In the experiment that had higher runoff water losses, antibiotic losses ranged from 1.2 to 1.8% of total extractable antibiotics in manure. In the experiment with lower runoff water losses, antibiotic losses varied from 0.2 to 0.6% of the total extractable antibiotics in manure. Manure analysis over time suggests that in situ degradation is an important mechanism for antibiotic losses. Degradation losses during manure stockpiling may exceed cumulative losses from runoff events. Storing manure in protected (i.e., covered) facilities could reduce the risk of aquatic contamination associated with manure stockpiling and other outdoor manure management practices.
Antibiotic Losses in Leaching and Surface Runoff from Manure‐Amended Agricultural Land
Authors: Dolliver Holly , Gupta Satish 
Published: May 2008

AbstractA 3‐yr field study quantified leaching and runoff losses of antibiotics from land application of liquid hog (chlortetracycline and tylosin) and solid beef (chlortetracycline, monensin, and tylosin) manures under chisel plowing and no‐tillage systems. The study was conducted in southwestern Wisconsin, a karst area with steep, shallow, macroporous soils. Relative mass losses of chlortetracycline, monensin, and tylosin were <5% of the total amount applied with manure. Chlortetracycline was only detected in runoff, whereas monensin and tylosin were detected in leachate and runoff. Highest concentrations of monensin and tylosin in the leachate were 40.9 and 1.2 μg L−1, respectively. Highest chlortetracycline, monensin, and tylosin concentrations in runoff were 0.5, 57.5, and 6.0 μg L−1, respectively. For all three antibiotics, >90% of detections and 99% of losses occurred during the non‐growing season due to fall manure application and slow degradation of antibiotics at cold temperatures. During years of high snowmelt, runoff accounted for nearly 100% of antibiotic losses, whereas during years of minimal snowmelt, runoff accounted for approximately 40% of antibiotic losses. Antibiotic losses were generally higher from the no‐tillage compared with chisel plow treatment due to greater water percolation as a result of macroporosity and greater runoff due to lack of surface roughness in the no‐tillage plots during the non‐growing season. The results from this study suggest that small quantities of dissolved antibiotics could potentially reach surface and ground waters in the Upper Midwestern USA from manure‐amended shallow macroporous soils underlain with fractured bedrock.
Application of Enzyme‐Linked Immunosorbent Assay Analysis for Determination of Monensin in Environmental Samples
Authors: Dolliver Holly , Kumar Kuldip , Gupta Satish , Singh Ashok 
Published: May 2008

AbstractThere is growing concern that antibiotic use in livestock production is contributing to contamination of soil and aquatic environments. Monensin, a polyether ionophore antibiotic, accounts for approximately 13% of total subtherapeutic livestock antibiotic usage in the USA and has been widely detected in aquatic environments. Due to insufficient ultraviolet absorbance, liquid chromatography analysis of monensin in environmental samples is limited to equipment with mass spectrometry (e.g., liquid chomatography–mass spectrometry [LC‐MS]). However, LC‐MS equipment is costly, and extensive sample preparation and clean‐up is often required. Rapid, low‐cost analytical techniques are needed to monitor for monensin residues in the environment. In this study, a commercially available enzyme‐linked immunosorbent assay (ELISA) for detecting monensin in animal feed extracts was evaluated for determination of monensin in water, soil, and manure. The monensin ELISA was highly sensitive, with limits of detection and quantification at 1.5 and 3.0 μg L−1, respectively. Recovery of monensin in spiked water samples was approximately 100%. Cross‐reactivity was not observed with similar polyether ionophores, tetracyclines, macrolides, or sulfonamides. Concentrations of monensin using ELISA were greater than concentrations measured with LC‐MS. This is attributed to cross‐reactivity of the monensin ELISA toward structurally similar monensin compounds, such as factors (slight naturally produced structural variants) and metabolites. Results from this study showed that ELISA can be a reliable, rapid, and low‐cost alternative to LC‐MS analysis of environmental samples.