Effective simultaneous removal of Pb(II) and Cd(II) ions by a new magnetic zeolite prepared from stem sweep

NASA Astrophysics Data System (ADS)

Safinejad, A.; Goudarzi, N.; Arab Chamjangali, M.; Bagherian, G.

2017-11-01

In this work, we prepared a new magnetic zeolite (MZ), as a sorbent, from stem sweep and used for the removal of lead and cadmium ions from aqueous solutions. Then the effective parameters involved in the removal efficiency of the studied ions were investigated. The synthetic MZ was characterized using x-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM). The best conditions for the preparation of MZ were found to be as follow: %Fe3O4 loaded  =  25, Si/Al  =  1.5, Na2O/SiO2  =  2.0, H2O/Na2O  =  75.0, crystallization time  =  20.0 h, and crystallization temperature  =  110 °C. The magnetic adsorbent was obtained by coating the zeolite with iron oxide nanoparticles. To study the sorption performance of the synthetic adsorbent, the single and binary systems including Pb(II) and Cd(II) ions were used. The effects of various parameters such as the solution pH, initial metal ion concentrations, amount of adsorbent, and contact time on the removal efficiency of the metal ions were studied. The results obtained showed that the adsorption isotherm data fitted well to the Langmuir isotherm, and that the adsorption kinetics of the metal ions in a binary system followed a pseudo-second order kinetic model.

3 CFR 13505 - Executive Order 13505 of March 9, 2009. Removing Barriers to Responsible Scientific Research...

Code of Federal Regulations, 2010 CFR

2010-01-01

... Barriers to Responsible Scientific Research Involving Human Stem Cells 13505 Order 13505 Presidential... Scientific Research Involving Human Stem Cells By the authority vested in me as President by the Constitution.... Research involving human embryonic stem cells and human non-embryonic stem cells has the potential to lead...

Phytoremediation of heavy metal copper (Cu2+) by sunflower (Helianthus annuus l.)

NASA Astrophysics Data System (ADS)

Mahardika, G.; Rinanti, A.; Fachrul, M. F.

2018-01-01

A study in microcosmic condition has been carried out to determine the effectiveness of Helianthus annuus as a hyperaccumulator plant for heavy metal, Copper (Cu2+), that exposed in the soil. Artificial pollutants containing Copper (Cu2+) 0, 60, 120, 180 ppm are exposed to uncontaminated soil. The 12-weeks old H. annuus seedling were grown in Cu2+ contaminated soil, with variations of absorption time 3, 6, and 9 weeks. Analysis of Cu2+ concentration on soil and H. annuus (root, stem, leaf) was analised by Atomic Absorbtion Spectrometry (AAS). H. annuus are capable for Cu2+ removal, and the highest removal of Cu2+ is 85.56%, the highest metal accumulation/bioconcentration factor (BCF) is 0.99 occurred at roots with 9 weeks of exposure time and the highest translocation factor (TF) is 0.71. This highest removal is five times better than absorption by stems and leaves. The results concluded, the use of H. annuus for phytoextraction of heavy metals Cu2+ in contaminated soil can be an alternative to the absorption of heavy metal Cu2+ with low concentration metals which is generally very difficult to do in physical-chemical removal.

Evaluation of Internal Brushing on Pinch Weld Quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korinko, P

2005-12-01

Post machining operations such as borescope inspection can cause linear indications down the length of the bore of fill stems. Often these indications are removed or obscured using rotary wire brushing. This study evaluated the effect this mechanical operation may have on pinch weld quality when relatively cold welds were made. A total of four stems with two levels of brushing of both Type 304L and 21-6-9 stainless steels were tested. In addition, two each of the Type 304L stems were Nitradd cleaned and the other two were aqueously cleaned; all four 21-6-9 stems were aqueously cleaned. All of themore » brushed stem areas exhibited more surface anomalies based on borescope evaluation. On average, the bond rating was a higher value (worse) for the brushed areas than the unadulterated areas for both Type 304L and 21-6-9 stems. The test method used may have biased the results towards a lesser quality bond for the brushed areas so additional testing is recommended.« less

Physiology of Movements in the Stems of Seedling Pisum sativum L. cv Alaska 1

PubMed Central

Britz, Steven J.; Galston, Arthur W.

1983-01-01

Phototropic response in etiolated pea (Pisum sativum L. cv Alaska) seedlings is poor. However, the curvature induced by unilateral blue light can be hastened and increased in magnitude by a previously administered red light pulse followed by several hours of darkness. Phytochrome is involved in the red light effect. Phototropic response was almost completely inhibited by removal of the apical bud and hook, but it was restored if exogenous indole-3-acetic acid was applied apically to the cut stump. Therefore, the stem contains both the phototropic photoreceptor and response mechanism. Perception of gravity and gravitropic response were also localized in the stem, but gravitropism was scarcely inhibited by decapitation. It was also observed that the kinetics and curvature pattern of gravitropism differed greatly from those of phototropism. Like phototropism, stem nutation required auxin and was promoted by red light. Unlike phototropism, photoenhanced nutational curvature required the apical hook and was propagated as a wave down the stem. Naphthylphthalamic acid inhibited, in order of decreasing effect, nutation, phototropism/gravitropism, and growth. Phototropism, gravitropism, and nutation appear to represent distinct forms of stem movement with fundamental differences in the mechanisms of curvature development. Images Fig. 3 PMID:16662824

Socializing with the neighbors: stem cells and their niche.

PubMed

Fuchs, Elaine; Tumbar, Tudorita; Guasch, Geraldine

2004-03-19

The potential of stem cells in regenerative medicine relies upon removing them from their natural habitat, propagating them in culture, and placing them into a foreign tissue environment. To do so, it is essential to understand how stem cells interact with their microenvironment, the so-called stem cell niche, to establish and maintain their properties. In this review, we examine adult stem cell niches and their impact on stem cell biology.

Logging residue removal after thinning in boreal forests: long-term impact on the nutrient status of Norway spruce and Scots pine needles.

PubMed

Luiro, Jukka; Kukkola, Mikko; Saarsalmi, Anna; Tamminen, Pekka; Helmisaari, Heljä-Sisko

2010-01-01

The aim of this study was to compare how conventional stem harvesting (CH) and whole-tree harvesting (WTH) in the first, and in some cases also in the second, thinning affect the needle nutrient status of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands in Finland. A series of 12 long-term field experiments was studied. The experiments were established during 1978-86. The effects of logging residue removal after thinnings on the needle nutrient concentrations were generally minor and without any overall trends, but there were differences between experiments. Trees tend to maintain their current needle nutrient concentrations at the same level by re-utilizing the nutrients stored in the older tissues and by changing C allocation in the whole tree. Thus, needle analysis should be combined with stem growth data in order to achieve a more comprehensive understanding of the effects of WTH on the nutrient status of trees.

Childhood Central Nervous System Embryonal Tumors Treatment

MedlinePlus

... lower back is numbed. High-dose chemotherapy with stem cell rescue High-dose chemotherapy with stem cell rescue is a way of giving high doses ... blood -forming cells destroyed by the cancer treatment. Stem cells (immature blood cells) are removed from the blood ...

In Situ Visualization of the Dynamics in Xylem Embolism Formation and Removal in the Absence of Root Pressure: A Study on Excised Grapevine Stems.

PubMed

Knipfer, Thorsten; Cuneo, Italo F; Brodersen, Craig R; McElrone, Andrew J

2016-06-01

Gas embolisms formed during drought can disrupt long-distance water transport through plant xylem vessels, but some species have the ability to remove these blockages. Despite evidence suggesting that embolism removal is linked to the presence of vessel-associated parenchyma, the underlying mechanism remains controversial and is thought to involve positive pressure generated by roots. Here, we used in situ x-ray microtomography on excised grapevine stems to determine if embolism removal is possible without root pressure, and if the embolism formation/removal affects vessel functional status after sample excision. Our data show that embolism removal in excised stems was driven by water droplet growth and was qualitatively identical to refilling in intact plants. When stem segments were rehydrated with H2O after excision, vessel refilling occurred rapidly (<1 h). The refilling process was substantially slower when polyethylene glycol was added to the H2O source, thereby providing new support for an osmotically driven refilling mechanism. In contrast, segments not supplied with H2O showed no refilling and increased embolism formation. Dynamic changes in liquid/wall contact angles indicated that the processes of embolism removal (i.e. vessel refilling) by water influx and embolism formation by water efflux were directly linked to the activity of vessel-associated living tissue. Overall, our results emphasize that root pressure is not required as a driving force for vessel refilling, and care should be taken when performing hydraulics measurements on excised plant organs containing living vessel-associated tissue, because the vessel behavior may not be static. © 2016 American Society of Plant Biologists. All Rights Reserved.

In Situ Visualization of the Dynamics in Xylem Embolism Formation and Removal in the Absence of Root Pressure: A Study on Excised Grapevine Stems1[OPEN

PubMed Central

Knipfer, Thorsten; Cuneo, Italo F.; Brodersen, Craig R.; McElrone, Andrew J.

2016-01-01

Gas embolisms formed during drought can disrupt long-distance water transport through plant xylem vessels, but some species have the ability to remove these blockages. Despite evidence suggesting that embolism removal is linked to the presence of vessel-associated parenchyma, the underlying mechanism remains controversial and is thought to involve positive pressure generated by roots. Here, we used in situ x-ray microtomography on excised grapevine stems to determine if embolism removal is possible without root pressure, and if the embolism formation/removal affects vessel functional status after sample excision. Our data show that embolism removal in excised stems was driven by water droplet growth and was qualitatively identical to refilling in intact plants. When stem segments were rehydrated with H2O after excision, vessel refilling occurred rapidly (<1 h). The refilling process was substantially slower when polyethylene glycol was added to the H2O source, thereby providing new support for an osmotically driven refilling mechanism. In contrast, segments not supplied with H2O showed no refilling and increased embolism formation. Dynamic changes in liquid/wall contact angles indicated that the processes of embolism removal (i.e. vessel refilling) by water influx and embolism formation by water efflux were directly linked to the activity of vessel-associated living tissue. Overall, our results emphasize that root pressure is not required as a driving force for vessel refilling, and care should be taken when performing hydraulics measurements on excised plant organs containing living vessel-associated tissue, because the vessel behavior may not be static. PMID:27208267

EFFECT OF METAL REMOVAL ON THE TOXICITY OF AIRBORNE PARTICULATE MATTER FROM THE UTAH VALLEY

EPA Science Inventory

Abstract:
Epidemiological studies have linked the inhalation of airborne particulate matter (PM) to increased morbidity and mortality in humans. However, the mechanism(s) of toxicity of these particles remains unclear. Some hypotheses state that the toxicity might stem fro...

EFFECT OF METAL REMOVAL ON THE TOXICITY OF AIRBORNE PARTICULATE MATTER FROM THE UTAH VALLEY

EPA Science Inventory

Epidemiological studies have linked the inhalation of airborne particulate matter (PM) to increased morbidity and mortality in humans. However, the mechanisms of toxicity of these particles remains unclear. Several hypotheses state that the toxicity might stem from PM transitio...

Removal of a well-fixed cementless femoral stem using a microsagittal saw.

PubMed

Kim, Young-Min; Lim, Soo Taek; Yoo, Jeong Joon; Kim, Hee Joong

2003-06-01

Well-fixed cementless femoral components are troublesome to extract. This article describes a technique to extract a well-fixed cementless stem in which the stem is extracted with a bent microsagittal saw blade after a longitudinal cortical window is made.

Diploid, but not haploid, human embryonic stem cells can be derived from microsurgically repaired tripronuclear human zygotes

PubMed Central

Fan, Yong; Li, Rong; Huang, Jin; Yu, Yang; Qiao, Jie

2013-01-01

Human embryonic stem cells have shown tremendous potential in regenerative medicine, and the recent progress in haploid embryonic stem cells provides new insights for future applications of embryonic stem cells. Disruption of normal fertilized embryos remains controversial; thus, the development of a new source for human embryonic stem cells is important for their usefulness. Here, we investigated the feasibility of haploid and diploid embryo reconstruction and embryonic stem cell derivation using microsurgically repaired tripronuclear human zygotes. Diploid and haploid zygotes were successfully reconstructed, but a large proportion of them still had a tripolar spindle assembly. The reconstructed embryos developed to the blastocyst stage, although the loss of chromosomes was observed in these zygotes. Finally, triploid and diploid human embryonic stem cells were derived from tripronuclear and reconstructed zygotes (from which only one pronucleus was removed), but haploid human embryonic stem cells were not successfully derived from the reconstructed zygotes when two pronuclei were removed. Both triploid and diploid human embryonic stem cells showed the general characteristics of human embryonic stem cells. These results indicate that the lower embryo quality resulting from abnormal spindle assembly contributed to the failure of the haploid embryonic stem cell derivation. However, the successful derivation of diploid embryonic stem cells demonstrated that microsurgical tripronuclear zygotes are an alternative source of human embryonic stem cells. In the future, improving spindle assembly will facilitate the application of triploid zygotes to the field of haploid embryonic stem cells. PMID:23255130

The Effect of In Vivo Mobilization of Bone Marrow Stem Cells on the Pancreas of Diabetic Albino Rats (A Histological & Immunohistochemical Study)

PubMed Central

Ismail, Zeinab Mohamed Kamel; Kamel, Ashraf Mahmoud Fawzy; Yacoub, Mira Farouk Youssef; Aboulkhair, Alshaymaa Gamal

2013-01-01

Background and Objectives The rapidly increasing number of diabetic patients across the world drew the attention to develop more effective therapeutic approaches. Recent investigations on newly differentiated insulin producing cells (IPCs) revealed that they could be derived from embryonic, adult mesenchymal and hematopoietic stem cells. This work was planned to evaluate the role of StemEnhance (Aphanizomenon flos-aquae [AFA] plant extract) in mobilizing naturally occurring bone marrow stem cells as well as in improving streptozotocin-induced diabetic rats. Methods and Results Twenty adult male albino rats were divided into four groups namely the control, the diabetic, the positive control-StemEnhance and the diabetic-StemEnhance groups. After diabetes induction by streptozotocin (STZ), rats received StemEnhance for four weeks. The mean number of blood CD34 immunopositive cells was measured by flowcytometry and random blood sugar was measured weekly. The pancreas was removed from the sacrificed rats and processed for staining with H&E and immunohistochemical staining for CD34+ve and insulin +ve cells. CD34+ve cells increased in the blood after introduction of StemEnhance. CD34+ve cells were observed in the pancreas and the insulin producing cells in the islets of Langerhans were increased from the second to the fourth week of treatment. Blood glucose level improved but it was still higher than the control level after four weeks of StemEnhance treatment. Conclusions This work points to the significant role of StemEnhance in stem cell mobilization and the improvement of diabetes mellitus. PMID:24298369

Biosorptive removal of inorganic arsenic species and fluoride from aqueous medium by the stem of Tecomella undulate.

PubMed

Brahman, Kapil Dev; Kazi, Tasneem Gul; Baig, Jameel Ahmed; Afridi, Hassan Imran; Arain, Sadaf Sadia; Saraj, Saima; Arain, Muhammad B; Arain, Salma Aslam

2016-05-01

Simultaneous removal of fluoride (F(-)), inorganic arsenic species, As(III) and As(V), from aqueous samples has been performed using an economic indigenous biosorbent (Stem of Tecomella undulata). The inorganic As species in water samples before and after biosorption were determined by cloud point and solid phase extraction methods, while F(-) was determined by ion chromatography. Batch experiments were carried out to evaluate the equilibrium adsorption isotherm studies for As(III), As(V) and F(-) in aqueous solutions. Several parameters of biosorption were optimized such as pH, biomass dosage, analytes concentration, time and temperature. The surface of biosorbent was characterized by SEM and FTIR. The FTIR study indicated the presence of carbonyl and amine functional groups which may have important role in the sorption/removal of these ions. Thermodynamic and kinetic study indicated that the biosorption of As(III), As(V) and F(-) were spontaneous, exothermic and followed by pseudo-second-order. Meanwhile, the interference study revealed that there was no significant effect of co-existing ions for the removal of inorganic As species and F(-) from aqueous samples (p > 0.05). It was observed that the indigenous biosorbent material simultaneously adsorbed As(III) (108 μg g(-1)), As(V) (159 μg g(-1)) and F(-) (6.16 mg g(-1)) from water at optimized conditions. The proposed biosorbent was effectively regenerated and efficiently used for several experiments, to remove the As(III), As(V) and F(-) from real water sample collected from endemic area of Pakistan. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simulating the effects of climatic variation on stem carbon accumulation of a ponderosa pine stand: comparison with annual growth increment data.

PubMed

Hunt, E R; Martin, F C; Running, S W

1991-01-01

Simulation models of ecosystem processes may be necessary to separate the long-term effects of climate change on forest productivity from the effects of year-to-year variations in climate. The objective of this study was to compare simulated annual stem growth with measured annual stem growth from 1930 to 1982 for a uniform stand of ponderosa pine (Pinus ponderosa Dougl.) in Montana, USA. The model, FOREST-BGC, was used to simulate growth assuming leaf area index (LAI) was either constant or increasing. The measured stem annual growth increased exponentially over time; the differences between the simulated and measured stem carbon accumulations were not large. Growth trends were removed from both the measured and simulated annual increments of stem carbon to enhance the year-to-year variations in growth resulting from climate. The detrended increments from the increasing LAI simulation fit the detrended increments of the stand data over time with an R(2) of 0.47; the R(2) increased to 0.65 when the previous year's simulated detrended increment was included with the current year's simulated increment to account for autocorrelation. Stepwise multiple linear regression of the detrended increments of the stand data versus monthly meteorological variables had an R(2) of 0.37, and the R(2) increased to 0.47 when the previous year's meteorological data were included to account for autocorrelation. Thus, FOREST-BGC was more sensitive to the effects of year-to-year climate variation on annual stem growth than were multiple linear regression models.

Survival of Atlantic salmon Salmo salar smolts through a hydropower complex.

PubMed

Stich, D S; Bailey, M M; Zydlewski, J D

2014-10-01

This study evaluated Atlantic salmon Salmo salar smolt survival through the lower Penobscot River, Maine, U.S.A., and characterized relative differences in proportional use and survival through the main-stem of the river and an alternative migration route, the Stillwater Branch. The work was conducted prior to removal of two main-stem dams and operational changes in hydropower facilities in the Stillwater Branch. Survival and proportional use of migration routes in the lower Penobscot were estimated from multistate (MS) models based on 6 years of acoustic telemetry data from 1669 smolts and 2 years of radio-telemetry data from 190 fish. A small proportion (0·12, 95% c.i. = 0·06-0·25) of smolts used the Stillwater Branch, and mean survival through the two operational dams in this part of the river was relatively high (1·00 and 0·97). Survival at Milford Dam, the dam that will remain in the main-stem of the Penobscot River, was relatively low (0·91), whereas survival through two dams that were removed was relatively high (0·99 and 0·98). Smolt survival could decrease in the Stillwater Branch with the addition of two new powerhouses while continuing to meet fish passage standards. The effects of removing two dams in the main-stem are expected to be negligible for smolt survival based on high survival observed from 2005 to 2012 at those locations. Survival through Milford Dam was been well below current regulatory standards, and thus improvement of passage at this location offers the best opportunity for improving overall smolt survival in the lower river. © 2014 The Fisheries Society of the British Isles.

Survival of Atlantic salmon Salmo salar smolts through a hydropower complex

USGS Publications Warehouse

Stich, D.S.; Bailey, M.M.; Zydlewski, Joseph D.

2014-01-01

This study evaluated Atlantic salmon Salmo salar smolt survival through the lower Penobscot River, Maine, U.S.A., and characterized relative differences in proportional use and survival through the main-stem of the river and an alternative migration route, the Stillwater Branch. The work was conducted prior to removal of two main-stem dams and operational changes in hydropower facilities in the Stillwater Branch. Survival and proportional use of migration routes in the lower Penobscot were estimated from multistate (MS) models based on 6 years of acoustic telemetry data from 1669 smolts and 2 years of radio-telemetry data from 190 fish. A small proportion (0·12, 95% c.i. = 0·06–0·25) of smolts used the Stillwater Branch, and mean survival through the two operational dams in this part of the river was relatively high (1·00 and 0·97). Survival at Milford Dam, the dam that will remain in the main-stem of the Penobscot River, was relatively low (0·91), whereas survival through two dams that were removed was relatively high (0·99 and 0·98). Smolt survival could decrease in the Stillwater Branch with the addition of two new powerhouses while continuing to meet fish passage standards. The effects of removing two dams in the main-stem are expected to be negligible for smolt survival based on high survival observed from 2005 to 2012 at those locations. Survival through Milford Dam was been well below current regulatory standards, and thus improvement of passage at this location offers the best opportunity for improving overall smolt survival in the lower river.

Removal of the methyl violet 2B dye from aqueous solution using sustainable adsorbent Artocarpus odoratissimus stem axis

NASA Astrophysics Data System (ADS)

Kooh, Muhammad Raziq Rahimi; Dahri, Muhammad Khairud; Lim, Linda B. L.

2017-11-01

This study investigates the potential of the stem axis of Artocarpus odoratissimus fruit (TSA) as an adsorbent for the removal of methyl violet 2B (MV). The functional group analysis was carried out using Fourier-transform infrared spectroscopy. Investigation of the effects of pH and ionic strength provide insights on the involvement of electrostatic attraction and hydrophobic-hydrophobic attraction between the adsorbent and adsorbates. Kinetics models (pseudo-first-order, pseudo-second-order, Weber-Morris and Boyd) and isotherm models (Langmuir, Freundlich and Dubinin-Raduskevich) were used for characterising the adsorption process. The Langmuir model predicted a high q m of 263.7 mg g-1. Thermodynamics studies indicate the adsorption system is spontaneous, endothermic and physical sorption dominant. The spent adsorbent was successfully regenerated using water and obtained adsorption capacity close to the unused adsorbent even after fifth cycle of washing.

Engaging Students in STEM Education

ERIC Educational Resources Information Center

Kennedy, T. J.; Odell, M. R. L.

2014-01-01

With the "flattening" of the global economy in the 21st century, the teaching of Science, Technology, Engineering, and Mathematics (STEM) has taken on new importance as economic competition has become truly global. STEM education has evolved into a meta-discipline, an integrated effort that removes the traditional barriers between these…

Stand dynamics following gap-scale exogenous disturbance in a single cohort mixed species stand in Morgan County, Tennessee

Treesearch

Brian S. Hughett; Wayne K. Clatterbuck

2014-01-01

Differences in composition, structure, and growth under canopy gaps created by the mortality of a single stem were analyzed using analysis of variance under two scenarios, with stem removed or with stem left as a standing snag. There were no significant differences in composition and structure of large diameter residual stems within upper canopy strata. Some...

Ecosystem engineering and manipulation of host plant tissues by the insect borer Oncideres albomarginata chamela.

PubMed

Calderón-Cortés, Nancy; Uribe-Mú, Claudia A; Martínez-Méndez, A Karen; Escalera-Vázquez, Luis H; Cristobal-Pérez, E Jacob; García-Oliva, Felipe; Quesada, Mauricio

2016-01-01

Ecosystem engineering by insect herbivores occurs as the result of structural modification of plants manipulated by insects. However, only few studies have evaluated the effect of these modifications on the plant responses induced by stem-borers that act as ecosystem engineers. In this study, we evaluated the responses induced by the herbivory of the twig-girdler beetle Oncideres albomarginata chamela (Cerambycidae: Lamiinae) on its host plant Spondias purpurea (Anacardiaceae), and its relationship with the ecosystem engineering process carried out by this stem-borer. Our results demonstrated that O. albomarginata chamela branch removal induced the development of lateral branches increasing the resources needed for the development of future insect generations, of its own offspring and of many other insect species. Detached branches represent habitats with high content of nitrogen and phosphorous, which eventually can be incorporated into the ecosystem, increasing nutrient cycling efficiency. Consequently, branch removal and the subsequent plant tissue regeneration induced by O. albomarginata chamela represent key mechanisms underlying the ecosystem engineering process carried out by this stem-borer, which enhances arthropod diversity in the ecosystem. Copyright © 2015 Elsevier Ltd. All rights reserved.

Peak Flow Responses and Recession Flow Characteristics After Thinning of Japanese Cypress Forest in a Headwater Catchment

EPA Science Inventory

We evaluated the effects of forest thinning on peak flow and recession characteristics of storm runoff in headwater catchments at Mie Prefecture, Japan. In catchment M5, 58.3% of stems were removed, whereas catchment M4 remained untreated as a control catchment. Storm precipitati...

Redox environment in stem and differentiated cells: A quantitative approach.

PubMed

Lyublinskaya, O G; Ivanova, Ju S; Pugovkina, N A; Kozhukharova, I V; Kovaleva, Z V; Shatrova, A N; Aksenov, N D; Zenin, V V; Kaulin, Yu A; Gamaley, I A; Nikolsky, N N

2017-08-01

Stem cells are believed to maintain a specific intracellular redox status through a combination of enhanced removal capacity and limited production of ROS. In the present study, we challenge this assumption by developing a quantitative approach for the analysis of the pro- and antioxidant ability of human embryonic stem cells in comparison with their differentiated descendants, as well as adult stem and non-stem cells. Our measurements showed that embryonic stem cells are characterized by low ROS level, low rate of extracellular hydrogen peroxide removal and low threshold for peroxide-induced cytotoxicity. However, biochemical normalization of these parameters to cell volume/protein leads to matching of normalized values in stem and differentiated cells and shows that tested in the present study cells (human embryonic stem cells and their fibroblast-like progenies, adult mesenchymal stem cells, lymphocytes, HeLa) maintain similar intracellular redox status. Based on these observations, we propose to use ROS concentration averaged over the cell volume instead of ROS level as a measure of intracellular redox balance. We show that attempts to use ROS level for comparative analysis of redox status of morphologically different cells could lead to false conclusions. Methods for the assessment of ROS concentration based on flow cytometry analysis with the use of H 2 DCFDA dye and HyPer, genetically encoded probe for hydrogen peroxide, are discussed. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Mesenchymal stem cells restore orientation and exploratory behavior of rats after brain injury.

PubMed

Sokolova, I B; Fedotova, O R; Tsikunov, S G; Polyntsev, D G

2011-05-01

We studied the effects of intravenous and intracerebral transplantation of MSC on restoration of orientation and exploratory behavior of Wistar-Kyoto rats after removal of the left motor cortex. Removal of the motor cortex led to a significant reduction of the number of behavioral acts in the open field test. Two weeks after removal of the motor cortex and intravenous transplantation, the animals were as inhibited as the controls, but during the next 10 weeks, the behavioral status of these rats remained unchanged, while controls exhibited further behavioral degradation. After injection of MSC into the brain, the behavior of rats with trauma did not change in comparison with intact rats over 10 weeks.

Effect of essential amino acids on enteroids: Methionine deprivation suppresses proliferation and affects differentiation in enteroid stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saito, Yuki; Iwatsuki, Ken; Hanyu, Hikaru

We investigated the effects of essential amino acids on intestinal stem cell proliferation and differentiation using murine small intestinal organoids (enteroids) from the jejunum. By selectively removing individual essential amino acids from culture medium, we found that 24 h of methionine (Met) deprivation markedly suppressed cell proliferation in enteroids. This effect was rescued when enteroids cultured in Met deprivation media for 12 h were transferred to complete medium, suggesting that Met plays an important role in enteroid cell proliferation. In addition, mRNA levels of the stem cell marker leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) decreased in enteroids grown in Met deprivationmore » conditions. Consistent with this observation, Met deprivation also attenuated Lgr5-EGFP fluorescence intensity in enteroids. In contrast, Met deprivation enhanced mRNA levels of the enteroendocrine cell marker chromogranin A (ChgA) and markers of K cells, enterochromaffin cells, goblet cells, and Paneth cells. Immunofluorescence experiments demonstrated that Met deprivation led to an increase in the number of ChgA-positive cells. These results suggest that Met deprivation suppresses stem cell proliferation, thereby promoting differentiation. In conclusion, Met is an important nutrient in the maintenance of intestinal stem cells and Met deprivation potentially affects cell differentiation. - Highlights: • Met influences the proliferation of enteroids. • Met plays a crucial role in the maintenance of stem cells. • Met deprivation potentially promotes differentiation into secretory cells.« less

Stemming Malay Text and Its Application in Automatic Text Categorization

NASA Astrophysics Data System (ADS)

Yasukawa, Michiko; Lim, Hui Tian; Yokoo, Hidetoshi

In Malay language, there are no conjugations and declensions and affixes have important grammatical functions. In Malay, the same word may function as a noun, an adjective, an adverb, or, a verb, depending on its position in the sentence. Although extensively simple root words are used in informal conversations, it is essential to use the precise words in formal speech or written texts. In Malay, to make sentences clear, derivative words are used. Derivation is achieved mainly by the use of affixes. There are approximately a hundred possible derivative forms of a root word in written language of the educated Malay. Therefore, the composition of Malay words may be complicated. Although there are several types of stemming algorithms available for text processing in English and some other languages, they cannot be used to overcome the difficulties in Malay word stemming. Stemming is the process of reducing various words to their root forms in order to improve the effectiveness of text processing in information systems. It is essential to avoid both over-stemming and under-stemming errors. We have developed a new Malay stemmer (stemming algorithm) for removing inflectional and derivational affixes. Our stemmer uses a set of affix rules and two types of dictionaries: a root-word dictionary and a derivative-word dictionary. The use of set of rules is aimed at reducing the occurrence of under-stemming errors, while that of the dictionaries is believed to reduce the occurrence of over-stemming errors. We performed an experiment to evaluate the application of our stemmer in text mining software. For the experiment, text data used were actual web pages collected from the World Wide Web to demonstrate the effectiveness of our Malay stemming algorithm. The experimental results showed that our stemmer can effectively increase the precision of the extracted Boolean expressions for text categorization.

The role of EDTA in phytoextraction of hexavalent and trivalent chromium by two willow trees.

PubMed

Yu, Xiao-Zhang; Gu, Ji-Dong

2008-04-01

Effects of the synthetic chelator ethylenediamine tetraacetate (EDTA) on uptake and internal translocation of hexavalent and trivalent chromium by plants were investigated. Two different concentrations of EDTA were studied for enhancing the uptake and translocation of Cr from the hydroponic solution spiked with K(2)CrO(4) or CrCl(3) maintained at 24.0 +/- 1 degrees C. Faster removal of Cr(3+) than Cr(6+) by hybrid willows (Salix matsudana Koidz x Salix alba L.) from the plant growth media was observed. Negligible effect of EDTA on the uptake of Cr(6+) was found, but significant decrease of the Cr concentration in roots was measured. Although the translocation of Cr(6+) within plant materials was detected in response to EDTA concentration, the amount of Cr(6+) translocated to the lower stems was considerably small. EDTA in the nutrient media showed a negative effect on the uptake of Cr(3+ )by hybrid willows; the removal rates of Cr(3+ )were significantly decreased. Translocation of Cr(3+) into the stems and leaves was undetectable, but roots were the exclusive sink for Cr(3+) accumulation. Weeping willows (Salix babylonica L.) showed lower removal rates for both chemical forms of Cr than hybrid willows. Although EDTA had a minor effect on Cr(6+ )uptake by weeping willows, positive effect on Cr(6+ )translocation within plant materials was observed. It was also determined that EDTA in plant growth media significantly decreased the amount of Cr(3+) taken up by plants, but significantly increased Cr(3+) mobilization from roots to stems. Results indicated that EDTA was unable to increase the uptake of Cr(6+) by both plant species, but translocation of Cr(6+)-EDTA within plant materials was possible. Addition of EDTA in the nutrient media showed a strong influence on the uptake and translocation of Cr(3+) in both willows. Cr(3+)-EDTA in tissues of weeping willows was more mobile than that in hybrid willows. The information has important implications for the use of metal chelator in plant nutritional research.

Expanded Stem Cells, Stromal-Vascular Fraction, and Platelet-Rich Plasma Enriched Fat: Comparing Results of Different Facial Rejuvenation Approaches in a Clinical Trial

PubMed Central

Rigotti, Gino; Charles-de-Sá, Luiz; Gontijo-de-Amorim, Natale Ferreira; Takiya, Christina Maeda; Amable, Paola Romina; Borojevic, Radovan; Benati, Donatella; Bernardi, Paolo; Sbarbati, Andrea

2016-01-01

Background In a previous study, the authors demonstrated that treatment with expanded adipose-derived stem cells or stromal vascular fraction (SVF)-enriched fat modify the pattern of the dermis in human beings, representing a skin rejuvenation effect. Considering that expanded stem cells require a cell factor, the authors wanted to assess similar results by replacing them with platelet-rich plasma (PRP), which is easier to obtain and for which an empirical regenerative effect has been already described. Objectives To determine if PRP injection could replace the cutaneous regenerative effect of adipose-derived stem cells. Methods This study was performed in 13 patients who were candidates for facelift. The patients underwent sampling of fat by liposuction from the abdomen and submitted to one of three protocols: injection of SVF-enriched fat or expanded adipose-derived stem cells or fat plus PRP in the preauricular areas. Fragments of skin were removed before and 3 months after treatment and analyzed by optical and electron microscopy. Results The use of fat plus PRP led to the presence of more pronounced inflammatory infiltrates and a greater vascular reactivity, increasing in vascular permeability and a certain reactivity of the nervous component. The addition of PRP did not improve the regenerative effect. Conclusion The use of PRP did not have significant advantages in skin rejuvenation over the use of expanded adipose-derived stem cells or SVF-enriched fat. The effect of increased vascular reactivity may be useful in pathological situations in which an intense angiogenesis is desirable, such as tissular ischemia. Level of Evidence: 4 Therapeutic PMID:26879294

A basic approach to fire injury of tree stems

Treesearch

R. E. Martin

1963-01-01

Fire has come to be widely used as a tool in wildland management, particularly in the South. Its usefulness in fire hazard reduction, removal of undesirable trees, and changing of cover types has been demonstrated. We are continually trying to improve fire use, however, by learning more of the specific effects of fire on different species of plants.

Runoff Responses to Forest Thinning at Plot and Catchment Scales in a Headwater Catchment Draining Japanese Cypress Forest

EPA Science Inventory

We examined the effect of forest thinning on runoff generation at plot and catchment scales in headwater basins draining a Japanese cypress (Chamaecyparis obtusa) forest. We removed 58.3% of the stems (corresponding to 43.2% of the basal area) in the treated headwater basin (catc...

Organ-level quorum sensing directs regeneration in hair stem cell populations

PubMed Central

Chen, Chih-Chiang; Wang, Lei; Plikus, Maksim V.; Jiang, Ting Xin; Murray, Philip J.; Ramos, Raul; Guerrero-Juarez, Christian F.; Hughes, Michael W; Lee, Oscar K.; Shi, Songtao; Widelitz, Randall B.; Lander, Arthur D.; Chuong, Cheng Ming

2015-01-01

SUMMARY Coordinated organ behavior is crucial for an effective response to environmental stimuli. By studying regeneration of hair follicles in response to patterned hair removal, we demonstrate that organ-level quorum sensing allows coordinated responses to skin injury. Removing hair at different densities leads to a regeneration of up to 5 times more neighboring, unplucked resting hairs, indicating activation of a collective decision-making process. Through data modeling, the range of the quorum signal was estimated to be on the order of 1 mm, greater than expected for a diffusible molecular cue. Molecular and genetic analysis uncovered a two-step mechanism, where release of CCL2 from injured hairs leads to recruitment of TNF-α secreting macrophages, which accumulate and signal to both plucked and unplucked follicles. By coupling immune response with regeneration, this mechanism allows skin to respond predictively to distress, disregarding mild injury, while meeting stronger injury with full-scale cooperative activation of stem cells. PMID:25860610

Amniotic Fluid-Derived Stem Cells for Cardiovascular Tissue Engineering Applications

PubMed Central

Petsche Connell, Jennifer; Camci-Unal, Gulden; Khademhosseini, Ali

2013-01-01

Recent research has demonstrated that a population of stem cells can be isolated from amniotic fluid removed by amniocentesis that are broadly multipotent and nontumorogenic. These amniotic fluid-derived stem cells (AFSC) could potentially provide an autologous cell source for treatment of congenital defects identified during gestation, particularly cardiovascular defects. In this review, the various methods of isolating, sorting, and culturing AFSC are compared, along with techniques for inducing differentiation into cardiac myocytes and endothelial cells. Although research has not demonstrated complete and high-yield cardiac differentiation, AFSC have been shown to effectively differentiate into endothelial cells and can effectively support cardiac tissue. Additionally, several tissue engineering and regenerative therapeutic approaches for the use of these cells in heart patches, injection after myocardial infarction, heart valves, vascularized scaffolds, and blood vessels are summarized. These applications show great promise in the treatment of congenital cardiovascular defects, and further studies of isolation, culture, and differentiation of AFSC will help to develop their use for tissue engineering, regenerative medicine, and cardiovascular therapies. PMID:23350771

Nuclear lamins are not required for lamina-associated domain organization in mouse embryonic stem cells.

PubMed

Amendola, Mario; van Steensel, Bas

2015-05-01

In mammals, the nuclear lamina interacts with hundreds of large genomic regions, termed lamina-associated domains (LADs) that are generally in a transcriptionally repressed state. Lamins form the major structural component of the lamina and have been reported to bind DNA and chromatin. Here, we systematically evaluate whether lamins are necessary for the LAD organization in murine embryonic stem cells. Surprisingly, removal of essentially all lamins does not have any detectable effect on the genome-wide interaction pattern of chromatin with emerin, a marker of the inner nuclear membrane. This suggests that other components of the lamina mediate these interactions. © 2015 The Authors.

Generation of stem cell-based bioartificial anterior cruciate ligament (ACL) grafts for effective ACL rupture repair.

PubMed

Kouroupis, Dimitrios; Kyrkou, Athena; Triantafyllidi, Eleni; Katsimpoulas, Michalis; Chalepakis, George; Goussia, Anna; Georgoulis, Anastasios; Murphy, Carol; Fotsis, Theodore

2016-09-01

In the present study, we combined stem cell technology with a non-absorbable biomaterial for the reconstruction of the ruptured ACL. Towards this purpose, multipotential stromal cells derived either from subcutaneous human adipose tissue (hAT-MSCs) or from induced pluripotent stem cells (iPSCs) generated from human foreskin fibroblasts (hiPSC-MSCs) were cultured on the biomaterial for 21days in vitro to generate a 3D bioartifical ACL graft. Stem cell differentiation towards bone and ligament at the ends and central part of the biomaterial was selectively induced using either BMP-2/FGF-2 or TGF-β/FGF-2 combinations, respectively. The bioartificial ACL graft was subsequently implanted in a swine ACL rupture model in place of the surgically removed normal ACL. Four months post-implantation, the tissue engineered ACL graft generated an ACL-like tissue exhibiting morphological and biochemical characteristics resembling those of normal ACL. Copyright © 2016 Helmholtz Zentrum München. Published by Elsevier B.V. All rights reserved.

Contamination mitigation strategies for scanning transmission electron microscopy.

PubMed

Mitchell, D R G

2015-06-01

Modern scanning transmission electron microscopy (STEM) enables imaging and microanalysis at very high magnification. In the case of aberration-corrected STEM, atomic resolution is readily achieved. However, the electron fluxes used may be up to three orders of magnitude greater than those typically employed in conventional STEM. Since specimen contamination often increases with electron flux, specimen cleanliness is a critical factor in obtaining meaningful data when carrying out high magnification STEM. A range of different specimen cleaning methods have been applied to a variety of specimen types. The contamination rate has been measured quantitatively to assess the effectiveness of cleaning. The methods studied include: baking, cooling, plasma cleaning, beam showering and UV/ozone exposure. Of the methods tested, beam showering is rapid, experimentally convenient and very effective on a wide range of specimens. Oxidative plasma cleaning is also very effective and can be applied to specimens on carbon support films, albeit with some care. For electron beam-sensitive materials, cooling may be the method of choice. In most cases, preliminary removal of the bulk of the contamination by methods such as baking or plasma cleaning, followed by beam showering, where necessary, can result in a contamination-free specimen suitable for extended atomic scale imaging and analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fifteen-year patterns of soil carbon and nitrogen following biomass harvesting

Treesearch

Valerie J. Kurth; Anthony W. D' Amato; Brian J. Palik; John B. Bradford

2014-01-01

The substitution of forest-derived woody biofuels for fossil fuel energy has garnered increasing attention in recent years, but information regarding the mid- and long-term effects on soil productivity is limited. We investigated 15-yr temporal trends in forest floor and mineral soil (0-30 cm) C and N pools in response to organic matter removal treatments (OMR; stem-...

Human Induced Pluripotent Stem Cells Free of Vector and Transgene Sequences

PubMed Central

Yu, Junying; Hu, Kejin; Smuga-Otto, Kim; Tian, Shulan; Stewart, Ron; Slukvin, Igor I.; Thomson, James A.

2009-01-01

Reprogramming differentiated human cells to induced pluripotent stem (iPS) cells has applications in basic biology, drug development, and transplantation. Human iPS cell derivation previously required vectors that integrate into the genome, which can create mutations and limit the utility of the cells in both research and clinical applications. Here we describe the derivation of human iPS cells using non-integrating episomal vectors. After removal of the episome, iPS cells completely free of vector and transgene sequences are derived that are similar to human embryonic stem (ES) cells in proliferative and developmental potential. These results demonstrate that reprogramming human somatic cells does not require genomic integration or the continued presence of exogenous reprogramming factors, and removes one obstacle to the clinical application of human iPS cells. PMID:19325077

Preservation of Antigen-Specific Functions of αβ T Cells and B Cells Removed from Hematopoietic Stem Cell Transplants Suggests Their Use As an Alternative Cell Source for Advanced Manipulation and Adoptive Immunotherapy.

PubMed

Li Pira, Giuseppina; Di Cecca, Stefano; Biagini, Simone; Girolami, Elia; Cicchetti, Elisabetta; Bertaina, Valentina; Quintarelli, Concetta; Caruana, Ignazio; Lucarelli, Barbarella; Merli, Pietro; Pagliara, Daria; Brescia, Letizia Pomponia; Bertaina, Alice; Montanari, Mauro; Locatelli, Franco

2017-01-01

Hematopoietic stem cell transplantation is standard therapy for numerous hematological diseases. The use of haploidentical donors, sharing half of the HLA alleles with the recipient, has facilitated the use of this procedure as patients can rely on availability of a haploidentical donor within their family. Since HLA disparity increases the risk of graft-versus-host disease, T-cell depletion has been used to remove alloreactive lymphocytes from the graft. Selective removal of αβ T cells, which encompass the alloreactive repertoire, combined with removal of B cells to prevent EBV-related lymphoproliferative disease, proved safe and effective in clinical studies. Depleted αβ T cells and B cells are generally discarded as by-products. Considering the possible use of donor T cells for donor lymphocyte infusions or for generation of pathogen-specific T cells as mediators of graft-versus-infection effect, we tested whether cells in the discarded fractions were functionally intact. Response to alloantigens and to viral antigens comparable to that of unmanipulated cells indicated a functional integrity of αβ T cells, in spite of the manipulation used for their depletion. Furthermore, B cells proved to be efficient antigen-presenting cells, indicating that antigen uptake, processing, and presentation were fully preserved. Therefore, we propose that separated αβ T lymphocytes could be employed for obtaining pathogen-specific T cells, applying available methods for positive selection, which eventually leads to indirect allodepletion. In addition, these functional T cells could undergo additional manipulation, such as direct allodepletion or genetic modification.

Preservation of Antigen-Specific Functions of αβ T Cells and B Cells Removed from Hematopoietic Stem Cell Transplants Suggests Their Use As an Alternative Cell Source for Advanced Manipulation and Adoptive Immunotherapy

PubMed Central

Li Pira, Giuseppina; Di Cecca, Stefano; Biagini, Simone; Girolami, Elia; Cicchetti, Elisabetta; Bertaina, Valentina; Quintarelli, Concetta; Caruana, Ignazio; Lucarelli, Barbarella; Merli, Pietro; Pagliara, Daria; Brescia, Letizia Pomponia; Bertaina, Alice; Montanari, Mauro; Locatelli, Franco

2017-01-01

Hematopoietic stem cell transplantation is standard therapy for numerous hematological diseases. The use of haploidentical donors, sharing half of the HLA alleles with the recipient, has facilitated the use of this procedure as patients can rely on availability of a haploidentical donor within their family. Since HLA disparity increases the risk of graft-versus-host disease, T-cell depletion has been used to remove alloreactive lymphocytes from the graft. Selective removal of αβ T cells, which encompass the alloreactive repertoire, combined with removal of B cells to prevent EBV-related lymphoproliferative disease, proved safe and effective in clinical studies. Depleted αβ T cells and B cells are generally discarded as by-products. Considering the possible use of donor T cells for donor lymphocyte infusions or for generation of pathogen-specific T cells as mediators of graft-versus-infection effect, we tested whether cells in the discarded fractions were functionally intact. Response to alloantigens and to viral antigens comparable to that of unmanipulated cells indicated a functional integrity of αβ T cells, in spite of the manipulation used for their depletion. Furthermore, B cells proved to be efficient antigen-presenting cells, indicating that antigen uptake, processing, and presentation were fully preserved. Therefore, we propose that separated αβ T lymphocytes could be employed for obtaining pathogen-specific T cells, applying available methods for positive selection, which eventually leads to indirect allodepletion. In addition, these functional T cells could undergo additional manipulation, such as direct allodepletion or genetic modification. PMID:28386262

Elements of the niche for adult stem cell expansion

PubMed Central

Redondo, Patricia A; Pavlou, Marina; Loizidou, Marilena; Cheema, Umber

2017-01-01

Adult stem cells are crucial for tissue homeostasis. These cells reside within exclusive locations in tissues, termed niches, which protect adult stem cell fidelity and regulate their many functions through biophysical-, biochemical- and cellular-mediated mechanisms. There is a growing understanding of how these mechanisms and their components contribute towards maintaining stem cell quiescence, self-renewal, expansion and differentiation patterns. In vitro expansion of adult stem cells is a powerful tool for understanding stem cell biology, and for tissue engineering and regenerative medicine applications. However, it is technically challenging, since adult stem cell removal from their native microenvironment has negative repercussions on their sustainability. In this review, we overview specific elements of the biomimetic niche and how recreating such elements can help in vitro propagation of adult stem cells. PMID:28890779

Elements of the niche for adult stem cell expansion.

PubMed

Redondo, Patricia A; Pavlou, Marina; Loizidou, Marilena; Cheema, Umber

2017-01-01

Adult stem cells are crucial for tissue homeostasis. These cells reside within exclusive locations in tissues, termed niches, which protect adult stem cell fidelity and regulate their many functions through biophysical-, biochemical- and cellular-mediated mechanisms. There is a growing understanding of how these mechanisms and their components contribute towards maintaining stem cell quiescence, self-renewal, expansion and differentiation patterns. In vitro expansion of adult stem cells is a powerful tool for understanding stem cell biology, and for tissue engineering and regenerative medicine applications. However, it is technically challenging, since adult stem cell removal from their native microenvironment has negative repercussions on their sustainability. In this review, we overview specific elements of the biomimetic niche and how recreating such elements can help in vitro propagation of adult stem cells.

Effect of EDTA and Tannic Acid on the Removal of Cd, Ni, Pb and Cu from Artificially Contaminated Soil by Althaea rosea Cavan.

PubMed

Cay, Seydahmet; Uyanik, Ahmet; Engin, Mehmet Soner; Kutbay, Hamdi Guray

2015-01-01

In this study an ornamental plant of Althaea rosea Cavan was investigated for its potential use in the removal of Cd, Ni, Pb and Cu from an artificially contaminated soil. Effect of two different chelating agents on the removal has also been studied by using EDTA (ethylenediaminetetracetic acid) and TA (tannic acid). Both EDTA and TA have led to higher heavy metal concentration in shoots and leaves compared to control plants. However EDTA is generally known as an effective agent in metal solubilisation of soil, in this study, TA was found more effective to induce metal accumulation in Althaea rosea Cavan under the studied conditions. In addition to this, EDTA is toxic to some species and restraining the growth of the plants. The higher BCF (Bio Concentration Factor) and TF (Translocation Factor) values obtained from stems and leaves by the effects of the chemical enhancers (EDTA and TA) show that Althaea rosea Cavan is a hyper accumulator for the studied metals and may be cultivated to clean the contaminated soils.

Ailanthus Altissima and Phragmites Australis for chromium removal from a contaminated soil.

PubMed

Ranieri, Ezio; Fratino, Umberto; Petrella, Andrea; Torretta, Vincenzo; Rada, Elena Cristina

2016-08-01

The comparative effectiveness for hexavalent chromium removal from irrigation water, using two selected plant species (Phragmites australis and Ailanthus altissima) planted in soil contaminated with hexavalent chromium, has been studied in the present work. Total chromium removal from water was ranging from 55 % (Phragmites) to 61 % (Ailanthus). After 360 days, the contaminated soil dropped from 70 (initial) to 36 and 41 mg Cr/kg (dry soil), for Phragmites and Ailanthus, respectively. Phragmites accumulated the highest amount of chromium in the roots (1910 mg Cr/kg(dry tissue)), compared with 358 mg Cr/kg(dry tissue) for Ailanthus roots. Most of chromium was found in trivalent form in all plant tissues. Ailanthus had the lowest affinity for Cr(VI) reduction in the root tissues. Phragmites indicated the highest chromium translocation potential, from roots to stems. Both plant species showed good potentialities to be used in phytoremediation installations for chromium removal.

Response to stem bending in forest shrubs: stem or shoot reorientation and shoot release.

PubMed

Wilson, B F

1997-10-01

Shrubs in the forest understory may be bent by their own weight or by overstory debris. To maintain height growth they must respond to bending by vertical growth of new shoots, reorientation of older axes, or by releasing preventitious buds to form epicormic shoots. I tested for these responses in Ilex verticillata L., Cornus amomum Mill., Gaylussacia baccata (Wang.) K. Koch, Viburnum cassinoides L., Hamamelis virginiana L., and Kalmia latifolia L. For each species, I removed potentially supporting vegetation adjacent to 20 stems, left 10 stems untreated to test for bending by self weight, and bent the remaining 10 stems to 45 degrees to simulate effects of fallen debris. Stem angles and curvatures were measured from before leaf out until just before leaf fall to detect either sagging from self weight or upward bending from tension wood action. Control stems initially leaned out of vertical and five of six species sagged further into a cantilever form. Several control stems failed and bent to the ground. Stems of H. virginiana, I. verticillata, and C. amomum formed tension wood, but only the first two species bent upward. Viburnum cassinoides, G. baccata, and K. latifolia formed no tension wood and sagged further down after being bent. Epicormic shoots formed with varying frequencies in all species except K. latifolia. Epicormic shoots were the major response in C. amomum, V. cassinoides, and G. baccata. New terminal shoots on bent stems recovered toward vertical in I. verticillata and K. latifolia. Negative gravitropic response of shoots was the only recovery mechanism for K. latifolia.

An external heat pulse method for measurement of sap flow through fruit pedicels, leaf petioles and other small-diameter stems.

PubMed

Clearwater, Michael J; Luo, Zhiwei; Mazzeo, Mariarosaria; Dichio, Bartolomeo

2009-12-01

The external heat ratio method is described for measurement of low rates of sap flow in both directions through stems and other plant organs, including fruit pedicels, with diameters up to 5 mm and flows less than 2 g h(-1). Calibration was empirical, with heat pulse velocity (v(h)) compared to gravimetric measurements of sap flow. In the four stem types tested (Actinidia sp. fruit pedicels, Schefflera arboricola petioles, Pittosporum crassifolium stems and Fagus sylvatica stems), v(h) was linearly correlated with sap velocity (v(s)) up to a v(s) of approximately 0.007 cm s(-1), equivalent to a flow of 1.8 g h(-1) through a 3-mm-diameter stem. Minimum detectable v(s) was approximately 0.0001 cm s(-1), equivalent to 0.025 g h(-1) through a 3-mm-diameter stem. Sensitivity increased with bark removal. Girdling had no effect on short-term measurements of in vivo sap flow, suggesting that phloem flows were too low to be separated from xylem flows. Fluctuating ambient temperatures increased variability in outdoor sap flow measurements. However, a consistent diurnal time-course of fruit pedicel sap flow was obtained, with flows towards 75-day-old kiwifruit lagging behind evaporative demand and peaking at 0.3 g h(-1) in the late afternoon.

Application of adipose-derived stem cells on scleral contact lens carrier in an animal model of severe acute alkaline burn.

PubMed

Espandar, Ladan; Caldwell, Delmar; Watson, Richard; Blanco-Mezquita, Tomas; Zhang, Shijia; Bunnell, Bruce

2014-07-01

To evaluate the therapeutic effect of human adipose-derived stem cells (hASCs) overlaid on a scleral contact lens (SCL) carrier in a rabbit model of ocular alkaline burn. After inducing alkaline burn in 11 New Zealand white rabbits, hASCs cultured on SCLs were placed on the right eye of 5 rabbits, SCLs without cells were used in 5, and no treatment was applied in 1 eye. Each eye was examined and photographed for corneal vascularization, opacities, and epithelial defect in week 1, 2, and 4 after surgery. After 1 month, rabbits were killed and the corneas were removed and cut in half for electron and light microscopy examination. Human adipose-derived stem cells were attached to SCL surface and confluent easily. Human adipose-derived stem cells on SCL eyes showed smaller epithelial defect, less corneal opacity, corneal neovascularization relative to SCL eyes. Both groups showed no symblepharon. However, the cornea in the untreated eye was melted in 2 weeks and developed severe symblepharon. Human adipose-derived stem cells on SCL can reduce inflammation and corneal haziness in severe ocular alkaline burn injury in rabbits.

Application of Adipose-Derived Stem Cells on Scleral Contact Lens Carrier in an Animal Model of Severe Acute Alkaline Burn

PubMed Central

Espandar, Ladan; Caldwell, Delmar; Watson, Richard; Blanco-Mezquita, Tomas; Zhang, Shijia; Bunnell, Bruce

2015-01-01

Purpose To evaluate the therapeutic effect of human adipose-derived stem cells (hASCs) overlaid on a scleral contact lens (SCL) carrier in a rabbit model of ocular alkaline burn. Materials and Methods After inducing alkaline burn in 11 New Zealand white rabbits, hASCs cultured on SCLs were placed on the right eye of 5 rabbits, SCLs without cells were used in 5, and no treatment was applied in 1 eye. Each eye was examined and photographed for corneal vascularization, opacities, and epithelial defect in week 1, 2, and 4 after surgery. After 1 month, rabbits were killed and the corneas were removed and cut in half for electron and light microscopy examination. Results Human adipose-derived stem cells were attached to SCL surface and confluent easily. Human adipose-derived stem cells on SCL eyes showed smaller epithelial defect, less corneal opacity, corneal neovascularization relative to SCL eyes. Both groups showed no symblepharon. However, the cornea in the untreated eye was melted in 2 weeks and developed severe symblepharon. Conclusion Human adipose-derived stem cells on SCL can reduce inflammation and corneal haziness in severe ocular alkaline burn injury in rabbits. PMID:24901976

Demographic changes following mechanical removal of exotic brown trout in an Intermountain West (USA), high-elevation stream

USGS Publications Warehouse

Saunders, W. Carl; Budy, Phaedra E.; Thiede, Gary P.

2015-01-01

Exotic species present a great threat to native fish conservation; however, eradicating exotics is expensive and often impractical. Mechanical removal can be ineffective for eradication, but nonetheless may increase management effectiveness by identifying portions of a watershed that are strong sources of exotics. We used mechanical removal to understand processes driving exotic brown trout (Salmo trutta) populations in the Logan River, Utah. Our goals were to: (i) evaluate the demographic response of brown trout to mechanical removal, (ii) identify sources of brown trout recruitment at a watershed scale and (iii) evaluate whether mechanical removal can reduce brown trout densities. We removed brown trout from 2 km of the Logan River (4174 fish), and 5.6 km of Right Hand Fork (RHF, 15,245 fish), a low-elevation tributary, using single-pass electrofishing. We compared fish abundance and size distributions prior to, and after 2 years of mechanical removal. In the Logan River, immigration to the removal reach and high natural variability in fish abundances limited the response to mechanical removal. In contrast, mechanical removal in RHF resulted in a strong recruitment pulse, shifting the size distribution towards smaller fish. These results suggest that, before removal, density-dependent mortality or emigration of juvenile fish stabilised adult populations and may have provided a source of juveniles to the main stem. Overall, in sites demonstrating strong density-dependent population regulation, or near sources of exotics, short-term mechanical removal has limited effects on brown trout populations but may help identify factors governing populations and inform large-scale management of exotic species.

7 CFR 52.1844 - Definition of terms.

Code of Federal Regulations, 2012 CFR

2012-01-01

... branches of the bunch. (b) A piece of stem means a portion of the branch or main stem. (c) Seeds refers to whole, fully developed seeds which have not been removed during the processing of seeded raisins with seeds. (d) Damaged raisins means raisins affected by sunburn, scars, insect injury, mechanical injury...

7 CFR 52.1844 - Definition of terms.

Code of Federal Regulations, 2011 CFR

2011-01-01

... branches of the bunch. (b) A piece of stem means a portion of the branch or main stem. (c) Seeds refers to whole, fully developed seeds which have not been removed during the processing of seeded raisins with seeds. (d) Damaged raisins means raisins affected by sunburn, scars, insect injury, mechanical injury...

Removal of Hexavalent Chromium by Adsorption on Microwave Assisted Activated Carbon Prepared from Stems of Leucas Aspera

NASA Astrophysics Data System (ADS)

Shanmugalingam, A.; Murugesan, A.

2018-05-01

This study reports adsorption of Cr(VI) ions from aqueous solution using activated carbon that was prepared from stems of Leucas aspera. Eight hundred and fifty watts power of microwave radiation, 12 min of radiation time, 60% of ZnCl2 solution and 24 h of impregnation time are the optimal parameters to prepare efficient carbon effective activated carbon. It was designated as MWLAC (Microwave assisted Zinc chloride activated Leucas aspera carbon). Various adsorption characteristics such as dose of the adsorbent, agitation time, initial Cr(VI) ion concentration, pH of the solution and temperature on adsorption were studied for removal of Cr(VI) ions from aqueous solution by batch mode. Also the equilibrium adsorption was analyzed by the Langmuir, Freundlich, Tempkin and D-R isotherm models. The order of best describing isotherms was given based on R2 value. The pseudo-second-order kinetic model best fitted with the Cr(VI) adsorption data. Thermodynamic parameters were also determined and results suggest that the adsorption process is a spontaneous, endothermic and proceeded with increased randomness.

Laser-Based Propagation of Human iPS and ES Cells Generates Reproducible Cultures with Enhanced Differentiation Potential

PubMed Central

Hohenstein Elliott, Kristi A.; Peterson, Cory; Soundararajan, Anuradha; Kan, Natalia; Nelson, Brandon; Spiering, Sean; Mercola, Mark; Bright, Gary R.

2012-01-01

Proper maintenance of stem cells is essential for successful utilization of ESCs/iPSCs as tools in developmental and drug discovery studies and in regenerative medicine. Standardization is critical for all future applications of stem cells and necessary to fully understand their potential. This study reports a novel approach for the efficient, consistent expansion of human ESCs and iPSCs using laser sectioning, instead of mechanical devices or enzymes, to divide cultures into defined size clumps for propagation. Laser-mediated propagation maintained the pluripotency, quality, and genetic stability of ESCs/iPSCs and led to enhanced differentiation potential. This approach removes the variability associated with ESC/iPSC propagation, significantly reduces the expertise, labor, and time associated with manual passaging techniques and provides the basis for scalable delivery of standardized ESC/iPSC lines. Adoption of standardized protocols would allow researchers to understand the role of genetics, environment, and/or procedural effects on stem cells and would ensure reproducible production of stem cell cultures for use in clinical/therapeutic applications. PMID:22701128

Fate of the unrevised cemented stem following cup only revision: 227 hips at an average of 6 years follow-up.

PubMed

McGonagle, L; Siney, P D; Raut, V V

2015-11-01

After primary total hip replacement, aseptic loosening of the acetabular cup is more common than loosening of the femoral stem. Removal of a well-fixed stem adds to operative time, blood loss, risk of bone loss and fracture. There is limited evidence that isolated cup revision can be a safe option in revision hip arthroplasty. We question the following regarding the unrevised cemented stem after isolated cup revision: 1) Does the unrevised stem require revision after isolated cup revision? 2) When is the stem subsequently revised? 3) Why is the stem subsequently revised? 4) Do unrevised stems exhibit radiographic loosening? We hypothesise that after isolated cup revision most unrevised stems do not need subsequent revision, and that most do not exhibit evidence of radiographic loosening. A retrospective analysis of all patients who underwent revision of the acetabular component only during revision hip arthroplasty between March 1970 and July 2013 was carried out. We assessed survival of the unrevised stem, reasons for subsequent revision, plus radiographic analysis for stem loosening. Two hundred and twenty-seven hips were included [215 patients with an average age at the time of primary surgery was 47 (13-70) years]. The Charnley stem was used in 161 cases; C-stem 65, Howse 1. Average time between primary surgery and cup revision was 15.9 (1.6-33.4) years. Average follow-up for all stems post-isolated cup revision was 6.1 (0.1-30.7) years. Twenty-eight stems (12.3%) were subsequently revised 5.1 (0.1-12.6) years after the isolated cup revision. Reasons for subsequent revision were: aseptic loosening (10); infection (8); dislocation (6); unreconstructable joint post-loose cup removal (2); fracture (2). Radiographic review was possible on 140 cases. Five femoral stems were revised and 2 others showed evidence of possible radiological loosening but were not revised. To our knowledge this is the largest series showing that isolated cup revision in the place of a well-fixed cemented stem is safe and is associated with ongoing good long-term survival of the stem. Level IV, retrospective case series. Copyright © 2015. Published by Elsevier Masson SAS.

[Effects of applying tea seed meal and EDTA on the speciation transformation and phyto-availability of nickel and zinc in soil].

PubMed

Yu, Bin; Xia, Hui-Long

2013-06-01

A pot experiment with sugarcane was conducted to study the effects of applying tea seed meal and EDTA on the speciation transformation and phyto-availability of nickel (Ni) and zinc (Zn) in soil. With the increasing application rate of tea seed meal, the biomass of sugarcane root, stem, and leaf increased gradually, but no significant difference was observed in the stem and leaf biomass between EDTA treatments and the control. Applying tea seed meal and EDTA increased the acid-soluble Ni and Zn contents in soil, and promoted the bioconcentration and translocation of Ni and Zn in sugarcane. Meanwhile, the strengthening effect increased gradually with the increasing application rate of tea seed meal. As compared with EDTA, tea seed meal was more efficient in improving the accumulation of Ni and Zn in sugarcane, and thus, made the sugarcane remove more Ni and Zn from soil. The Ni and Zn contents in sugarcane stem and leaf had significant positive correlations with the application rate of tea seed meal, while the Ni and Zn contents in sugarcane root were significantly negatively correlated with the application rate of tea seed meal.

Immune evasion through competitive inhibition: the shielding effect of cancer non-stem cells.

PubMed

Kareva, Irina

2015-01-07

It has been recently proposed that the two emerging hallmarks of cancer, namely altered glucose metabolism and immune evasion, may in fact be fundamentally linked. This connection comes from up-regulation of glycolysis by tumor cells, which can lead to active competition for resources in the tumor microenvironment between tumor and immune cells. Here it is further proposed that cancer stem cells (CSCs) can circumvent the anti-tumor immune response by creating a "protective shield" of non-stem cancer cells around them. This shield can protect the CSCs both by creating a physical barrier between them and cytotoxic lymphocytes (CTLs), and by promoting competition for the common resources, such as glucose, between non-stem cancer cells and CTLs. The implications of this hypothesis are investigated using an agent-based model, leading to a prediction that relative CSC to non-CSC ratio will vary depending on the strength of the host immune response. A discussion of possible therapeutic approaches concludes the paper, suggesting that a chemotherapeutic regimen consisting of regular pulsed doses, i.e., metronomic chemotherapy, would yield the best clinical outcome by removing the "protective shield" and thus allowing CTLs to most effectively reach and eliminate CSCs. Copyright © 2014 Elsevier Ltd. All rights reserved.

'Agglutination and flocculation' of stem cells collected by apheresis due to cryofibrinogen.

PubMed

Siegenthaler, M A; Vu, D-H; Ebnöther, M; Ketterer, N; Luthi, F; Schmid, P; Bargetzi, M; Gasparini, D; Tissot, J-D

2004-04-01

Collection of peripheral stem cells by apheresis is a well-described process. Here, investigations concerning 'agglutination and flocculation' of stem cells collected from two patients are described. In both cases, cryoproteins were observed and cryofibrinogen was identified using high-resolution two-dimensional electrophoresis. In one case, peripheral stem cells were collected after a second course of mobilization, and the cells were immediately washed at 37 degrees C before being frozen, allowing their use, despite the presence of cryofibrinogen. In the other case, 'agglutination' was reversed by warming the bag, and plasma was removed before freezing.

Effects of different feeder layers on culture of bovine embryonic stem cell-like cells in vitro.

PubMed

Cong, Shan; Cao, Guifang; Liu, Dongjun

2014-12-01

To find a suitable feeder layer is important for successful culture conditions of bovine embryonic stem cell-like cells. In this study, expression of pluripotency-related genes OCT4, SOX2 and NANOG in bovine embryonic stem cell-like cells on mouse embryonic fibroblast feeder layers at 1-5 passages were monitored in order to identify the possible reason that bovine embryonic stem cell-like cells could not continue growth and passage. Here, we developed two novel feeder layers, mixed embryonic fibroblast feeder layers of mouse and bovine embryonic fibroblast at different ratios and sources including mouse fibroblast cell lines. The bovine embryonic stem cell-like cells generated in our study displayed typical stem cell morphology and expressed specific markers such as OCT4, stage-specific embryonic antigen 1 and 4, alkaline phosphatase, SOX2, and NANOG mRNA levels. When feeder layers and cell growth factors were removed, the bovine embryonic stem cell-like cells formed embryoid bodies in a suspension culture. Furthermore, we compared the expression of the pluripotent markers during bovine embryonic stem cell-like cell in culture on mixed embryonic fibroblast feeder layers, including mouse fibroblast cell lines feeder layers and mouse embryonic fibroblast feeder layers by real-time quantitative polymerase chain reaction. Results suggested that mixed embryonic fibroblast and sources including mouse fibroblast cell lines feeder layers were more suitable for long-term culture and growth of bovine embryonic stem cell-like cells than mouse embryonic fibroblast feeder layers. The findings may provide useful experimental data for the establishment of an appropriate culture system for bovine embryonic stem cell lines.

Removing the tree-ring width biological trend using expected basal area increment

Treesearch

Franco Biondi; Fares Qeadan

2008-01-01

One of the main elements of dendrochronological standardization is the removal of the biological trend, i.e., the progressive decline of ring width along a cross-sectional radius that is mostly caused by the corresponding increase in stem diameter over time. A very common option for removing this biological trend is to fit a modified negative exponential curve to the...

Stem cell-based biological tooth repair and regeneration

PubMed Central

Volponi, Ana Angelova; Pang, Yvonne; Sharpe, Paul T.

2010-01-01

Teeth exhibit limited repair in response to damage, and dental pulp stem cells probably provide a source of cells to replace those damaged and to facilitate repair. Stem cells in other parts of the tooth, such as the periodontal ligament and growing roots, play more dynamic roles in tooth function and development. Dental stem cells can be obtained with ease, making them an attractive source of autologous stem cells for use in restoring vital pulp tissue removed because of infection, in regeneration of periodontal ligament lost in periodontal disease, and for generation of complete or partial tooth structures to form biological implants. As dental stem cells share properties with mesenchymal stem cells, there is also considerable interest in their wider potential to treat disorders involving mesenchymal (or indeed non-mesenchymal) cell derivatives, such as in Parkinson's disease. PMID:21035344

Tassel Removal Positively Affects Biomass Production Coupled with Significantly Increasing Stem Digestibility in Switchgrass

PubMed Central

Zhao, Chunqiao; Fan, Xifeng; Hou, Xincun; Zhu, Yi; Yue, Yuesen; Zhang, Shuang; Wu, Juying

2015-01-01

In this study, tassels of Cave-in-Rock (upland) and Alamo (lowland) were removed at or near tassel emergence to explore its effects on biomass production and quality. Tassel-removed (TR) Cave-in-Rock and Alamo both exhibited a significant (P<0.05) increase in plant heights (not including tassel length), tiller number, and aboveground biomass dry weight (10% and 12%, 30% and 13%, 13% and 18%, respectively by variety) compared to a control (CK) treatment. Notably, total sugar yields of TR Cave-in-Rock and Alamo stems increased significantly (P<0.05 or 0.01) by 19% and 19%, 21% and 14%, 52% and 18%, respectively by variety, compared to those of control switchgrass under 3 treatments by direct enzymatic hydrolysis (DEH), enzymatic hydrolysis after 1% NaOH pretreatment (EHAL) and enzymatic hydrolysis after 1% H2SO4 pretreatment (EHAC). These differences were mainly due to significantly (P<0.05 or 0.01) higher cellulose content, lower cellulose crystallinity indexes (CrI) caused by higher arabinose (Ara) substitution in xylans, and lower S/G ratio in lignin. However, the increases of nitrogen (N) and sulphur (S) concentration negatively affects the combustion quality of switchgrass aboveground biomass. This work provides information for increasing biomass production and quality in switchgrass and also facilitates the inhibition of gene dispersal of switchgrass in China. PMID:25849123

Keystone effects of an alien top-predator stem extinctions of native mammals

PubMed Central

Letnic, Mike; Koch, Freya; Gordon, Chris; Crowther, Mathew S.; Dickman, Christopher R.

2009-01-01

Alien predators can have catastrophic effects on ecosystems and are thought to be much more harmful to biodiversity than their native counterparts. However, trophic cascade theory and the mesopredator release hypothesis predict that the removal of top predators will result in the reorganization of trophic webs and loss of biodiversity. Using field data collected throughout arid Australia, we provide evidence that removal of an alien top-predator, the dingo, has cascading effects through lower trophic levels. Dingo removal was linked to increased activity of herbivores and an invasive mesopredator, the red fox (Vulpes vulpes), and to the loss of grass cover and native species of small mammals. Using species distribution data, we predict that reintroducing or maintaining dingo populations would produce a net benefit for the conservation of threatened native mammals across greater than 2.42 × 106 km2 of Australia. Our study provides evidence that an alien top predator can assume a keystone role and be beneficial for biodiversity conservation, and also that mammalian carnivores more generally can generate strong trophic cascades in terrestrial ecosystems. PMID:19535372

Bi-stem gripping apparatus

NASA Technical Reports Server (NTRS)

Sanders, Fred G. (Inventor)

1988-01-01

This invention relates to devices which grip cylindrical structures and more particularly to a device which has three arcuate gripping members having frictional surfaces for gripping and compressing a bi-stem. The bi-stem gripping apparatus is constructed having a pair of side gripping members, and an intermediate gripping member disposed between them. Sheets of a gum stock silicone rubber with frictional gripping surfaces are bonded to the inner region of the gripping members and provide frictional engagement between the bi-stem and the apparatus. A latch secures the gripping apparatus to a bi-stem, and removable handles are attached, allowing an astronaut to pull the bi-stem from its cassette. A tethering ring on the outside of the gripping apparatus provides a convenient point to which a lanyard may be attached.

Bacterial SPOR domains are recruited to septal peptidoglycan by binding to glycan strands that lack stem peptides

PubMed Central

Yahashiri, Atsushi; Jorgenson, Matthew A.; Weiss, David S.

2015-01-01

Bacterial SPOR domains bind peptidoglycan (PG) and are thought to target proteins to the cell division site by binding to “denuded” glycan strands that lack stem peptides, but uncertainties remain, in part because septal-specific binding has yet to be studied in a purified system. Here we show that fusions of GFP to SPOR domains from the Escherichia coli cell-division proteins DamX, DedD, FtsN, and RlpA all localize to septal regions of purified PG sacculi obtained from E. coli and Bacillus subtilis. Treatment of sacculi with an amidase that removes stem peptides enhanced SPOR domain binding, whereas treatment with a lytic transglycosylase that removes denuded glycans reduced SPOR domain binding. These findings demonstrate unequivocally that SPOR domains localize by binding to septal PG, that the physiologically relevant binding site is indeed a denuded glycan, and that denuded glycans are enriched in septal PG rather than distributed uniformly around the sacculus. Accumulation of denuded glycans in the septal PG of both E. coli and B. subtilis, organisms separated by 1 billion years of evolution, suggests that sequential removal of stem peptides followed by degradation of the glycan backbone is an ancient feature of PG turnover during bacterial cell division. Linking SPOR domain localization to the abundance of a structure (denuded glycans) present only transiently during biogenesis of septal PG provides a mechanism for coordinating the function of SPOR domain proteins with the progress of cell division. PMID:26305949

Long-term in-vivo tumorigenic assessment of human culture-expanded adipose stromal/stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacIsaac, Zoe Marie, E-mail: zmm4a@virgina.edu; Shang, Hulan, E-mail: shanghulan@gmail.com; Agrawal, Hitesh, E-mail: hiteshdos@hotmail.com

2012-02-15

After more than a decade of extensive experimentation, the promise of stem cells to revolutionize the field of medicine has negotiated their entry into clinical trial. Adipose tissue specifically holds potential as an attainable and abundant source of stem cells. Currently undergoing investigation are adipose stem cell (ASC) therapies for diabetes and critical limb ischemia, among others. In the enthusiastic pursuit of regenerative therapies, however, questions remain regarding ASC persistence and migration, and, importantly, their safety and potential for neoplasia. To date, assays of in vivo ASC activity have been limited by early end points. We hypothesized that with time,more » ASCs injected subcutaneously undergo removal by normal tissue turnover and homeostasis, and by the host's immune system. In this study, a high dose of culture expanded ASCs was formulated and implanted as multicellular aggregates into immunocompromised mice, which were maintained for over one year. Animals were monitored for toxicity, and surviving cells quantified at study endpoint. No difference in growth/weight or lifespan was found between cell-treated and vehicle treated animals, and no malignancies were detected in treated animals. Moreover, real-time PCR for a human specific sequence, ERV-3, detected no persistent ASCs. With the advent of clinical application, clarification of currently enigmatic stem cell properties has become imperative. Our study represents the longest duration determination of stem cell activity in vivo, and contributes strong evidence in support of the safety of adipose derived stem cell applications. -- Highlights: Black-Right-Pointing-Pointer Adipose stem cells promise novel clinical therapies. Black-Right-Pointing-Pointer Before clinical translation, safety profiles must be further elucidated. Black-Right-Pointing-Pointer Subcutaneously injected non-autologous adipose stem cells do not form tumors. Black-Right-Pointing-Pointer Subcutaneously injected non-autologous adipose stem cells undergo complete removal by one year.« less

Modeling Coast Redwood Variable Retention Management Regimes

Treesearch

John-Pascal Berrill; Kevin O' Hara

2007-01-01

Variable retention is a flexible silvicultural system that provides forest managers with an alternative to clearcutting. While much of the standing volume is removed in one harvesting operation, residual stems are retained to provide structural complexity and wildlife habitat functions, or to accrue volume before removal during subsequent stand entries. The residual...

Optimizing lodgepole pine submerchantable log thermomechanical pulp

Treesearch

Gary C. Myers

2004-01-01

To restore and maintain ecosystem health and function in the western interior of the United States, many small-diameter stems need to be removed from densely stocked stands. These stems are considered nonusable or underutilized (good, economical uses need to be developed). As of now, the most logical use for the small-diameter resource is pulp. In this study,...

Effect of EDTA on Pb(II) Uptake and Translocation by Tumbleweed (Salsola Kali): Agar and Hydroponics Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

de la Rosa, Guadalupe; Gardea-Torresdey, Jorge L.; Peralta-Videa, Jose R.

Environmental accumulation of Pb represents a worldwide health hazard. While conventional cleanup techniques are generally expensive and soil disturbing, phytoremediation represents an inexpensive friendly option for the removal of contaminants from soil and water. In this research, tumbleweed (Salsola kali) plants exposed for 15 days to Pb(NO3)2 at 80 and 125 ppm in hydroponics and agar media, demonstrated a high capacity to uptake lead. The results showed that the plants cultivated in agar accumulated 25563, 5534 and 2185 mg Pb kg-1 DW in roots, stems and leaves, respectively. Moreover, Pb concentrations found in hydroponically grown tumbleweed plants tissues were 30744,more » 1511 and 1421 mg kg-1 DW in roots, stems and leaves, respectively. It was observed that EDTA enhanced Pb translocation. No Pb phytotoxic effects were observed during the experimental time period. Cellular structural features were also observed using TEM.« less

Environmental Nanoscience: Turning Outreach Activities into a College Freshman Seminar

NASA Astrophysics Data System (ADS)

Nguyen, M. L.; Lau, B.

2017-12-01

Teaching nano concepts can be a daunting task due to the varying science backgrounds of the audience. Nonetheless, nanoscience education is important as nanotechnology expands. Our perspective is that nano education must be available at earlier stages than what is currently available. Through outreach activities, we examined how high school students and STEM middle/high school teachers approached answering questions about nanomaterials and the environment to design an effective freshman-level college seminar with achievable course goals. Specifically, participants were asked: 1) what color would you expect gold nanoparticles to be; 2) what are ways we can remove nanomaterials from the environment; and 3) what do you expect will happen to nanomaterials when salt is introduced into the system? Initial analysis showed STEM middle and high school teachers and high school students responded similarly. In response to question 1, the majority of the responses suggested color was a function of size. For question 2, both groups suggested the use of filters, magnets or a chemical reaction to remove the nanomaterials. For question 3, both groups expected a chemical reaction to occur. Understanding how foundational high school STEM concepts influenced responses could assist in the curriculum development for an introductory undergraduate nanoscience course. For example, familiar principles of physics and chemistry appeared to direct student responses. From these results, we developed three course goals to test in our college freshman seminar: 1) differentiate between properties of nanomaterials and conventional materials; 2) describe the role of nanomaterials in household items; and 3) form an opinion on the potential impacts of nanoscience and technology on the human health and the environment. Surveys from our first semester showed that the seminar was effective in achieving all course goals for the majority of students.

Simulation of Temperature, Nutrients, Biochemical Oxygen Demand, and Dissolved Oxygen in the Catawba River, South Carolina, 1996-97

USGS Publications Warehouse

Feaster, Toby D.; Conrads, Paul; Guimaraes, Wladmir B.; Sanders, Curtis L.; Bales, Jerad D.

2003-01-01

Time-series plots of dissolved-oxygen concentrations were determined for various simulated hydrologic and point-source loading conditions along a free-flowing section of the Catawba River from Lake Wylie Dam to the headwaters of Fishing Creek Reservoir in South Carolina. The U.S. Geological Survey one-dimensional dynamic-flow model, BRANCH, was used to simulate hydrodynamic data for the Branched Lagrangian Transport Model. Waterquality data were used to calibrate the Branched Lagrangian Transport Model and included concentrations of nutrients, chlorophyll a, and biochemical oxygen demand in water samples collected during two synoptic sampling surveys at 10 sites along the main stem of the Catawba River and at 3 tributaries; and continuous water temperature and dissolved-oxygen concentrations measured at 5 locations along the main stem of the Catawba River. A sensitivity analysis of the simulated dissolved-oxygen concentrations to model coefficients and data inputs indicated that the simulated dissolved-oxygen concentrations were most sensitive to watertemperature boundary data due to the effect of temperature on reaction kinetics and the solubility of dissolved oxygen. Of the model coefficients, the simulated dissolved-oxygen concentration was most sensitive to the biological oxidation rate of nitrite to nitrate. To demonstrate the utility of the Branched Lagrangian Transport Model for the Catawba River, the model was used to simulate several water-quality scenarios to evaluate the effect on the 24-hour mean dissolved-oxygen concentrations at selected sites for August 24, 1996, as simulated during the model calibration period of August 23 27, 1996. The first scenario included three loading conditions of the major effluent discharges along the main stem of the Catawba River (1) current load (as sampled in August 1996); (2) no load (all point-source loads were removed from the main stem of the Catawba River; loads from the main tributaries were not removed); and (3) fully loaded (in accordance with South Carolina Department of Health and Environmental Control National Discharge Elimination System permits). Results indicate that the 24-hour mean and minimum dissolved-oxygen concentrations for August 24, 1996, changed from the no-load condition within a range of - 0.33 to 0.02 milligram per liter and - 0.48 to 0.00 milligram per liter, respectively. Fully permitted loading conditions changed the 24-hour mean and minimum dissolved-oxygen concentrations from - 0.88 to 0.04 milligram per liter and - 1.04 to 0.00 milligram per liter, respectively. A second scenario included the addition of a point-source discharge of 25 million gallons per day to the August 1996 calibration conditions. The discharge was added at S.C. Highway 5 or at a location near Culp Island (about 4 miles downstream from S.C. Highway 5) and had no significant effect on the daily mean and minimum dissolved-oxygen concentration. A third scenario evaluated the phosphorus loading into Fishing Creek Reservoir; four loading conditions of phosphorus into Catawba River were simulated. The four conditions included fully permitted and actual loading conditions, removal of all point sources from the Catawba River, and removal of all point and nonpoint sources from Sugar Creek. Removing the point-source inputs on the Catawba River and the point and nonpoint sources in Sugar Creek reduced the organic phosphorus and orthophosphate loadings to Fishing Creek Reservoir by 78 and 85 percent, respectively.

Efficient generation of transgene-free human induced pluripotent stem cells (iPSCs) by temperature-sensitive Sendai virus vectors

PubMed Central

Ban, Hiroshi; Nishishita, Naoki; Fusaki, Noemi; Tabata, Toshiaki; Saeki, Koichi; Shikamura, Masayuki; Takada, Nozomi; Inoue, Makoto; Hasegawa, Mamoru; Kawamata, Shin; Nishikawa, Shin-Ichi

2011-01-01

After the first report of induced pluripotent stem cells (iPSCs), considerable efforts have been made to develop more efficient methods for generating iPSCs without foreign gene insertions. Here we show that Sendai virus vector, an RNA virus vector that carries no risk of integrating into the host genome, is a practical solution for the efficient generation of safer iPSCs. We improved the Sendai virus vectors by introducing temperature-sensitive mutations so that the vectors could be easily removed at nonpermissive temperatures. Using these vectors enabled the efficient production of viral/factor-free iPSCs from both human fibroblasts and CD34+ cord blood cells. Temperature-shift treatment was more effective in eliminating remaining viral vector-related genes. The resulting iPSCs expressed human embryonic stem cell markers and exhibited pluripotency. We suggest that generation of transgene-free iPSCs from cord blood cells should be an important step in providing allogeneic iPSC-derived therapy in the future. PMID:21821793

Leptin reverses corticosterone-induced inhibition of neural stem cell proliferation through activating the NR2B subunits of NMDA receptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Wen-Zhu; Anesthesia and Operation Center, Chinese PLA General Hospital, Beijing 100853; Miao, Yu-Liang

Highlights: • Leptin promotes the proliferation of neural stem cells isolated from embryonic mouse hippocampus. • Leptin reverses corticosterone-induced inhibition of neural stem cell proliferation. • The effects of leptin are partially mediated by upregulating NR2B subunits. - Abstract: Corticosterone inhibits the proliferation of hippocampal neural stem cells (NSCs). The removal of corticosterone-induced inhibition of NSCs proliferation has been reported to contribute to neural regeneration. Leptin has been shown to regulate brain development, improve angiogenesis, and promote neural regeneration; however, its effects on corticosterone-induced inhibition of NSCs proliferation remain unclear. Here we reported that leptin significantly promoted the proliferation ofmore » hippocampal NSCs in a concentration-dependent pattern. Also, leptin efficiently reversed the inhibition of NSCs proliferation induced by corticosterone. Interestingly, pre-treatment with non-specific NMDA antagonist MK-801, specific NR2B antagonist Ro 25-6981, or small interfering RNA (siRNA) targeting NR2B, significantly blocked the effect of leptin on corticosterone-induced inhibition of NSCs proliferation. Furthermore, corticosterone significantly reduced the protein expression of NR2B, whereas pre-treatment with leptin greatly reversed the attenuation of NR2B expression caused by corticosterone in cultured hippocampal NSCs. Our findings demonstrate that leptin reverses the corticosterone-induced inhibition of NSCs proliferation. This process is, at least partially mediated by increased expression of NR2B subunits of NMDA receptors.« less

Rescuing Ecosystems from Extinction Cascades

NASA Astrophysics Data System (ADS)

Sahasrabudhe, Sagar; Motter, Adilson

2010-03-01

Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

A Field Trial of TCE Phytoremediation by Genetically Modified Poplars Expressing Cytochrome P450 2E1.

PubMed

Legault, Emily K; James, C Andrew; Stewart, Keith; Muiznieks, Indulis; Doty, Sharon L; Strand, Stuart E

2017-06-06

A controlled field study was performed to evaluate the effectiveness of transgenic poplars for phytoremediation. Three hydraulically contained test beds were planted with 12 transgenic poplars, 12 wild type (WT) poplars, or left unplanted, and dosed with equivalent concentrations of trichloroethylene (TCE). Removal of TCE was enhanced in the transgenic tree bed, but not to the extent of the enhanced removal observed in laboratory studies. Total chlorinated ethene removal was 87% in the CYP2E1 bed, 85% in the WT bed, and 34% in the unplanted bed in 2012. Evapotranspiration of TCE from transgenic leaves was reduced by 80% and diffusion of TCE from transgenic stems was reduced by 90% compared to WT. Cis-dichloroethene and vinyl chloride levels were reduced in the transgenic tree bed. Chloride ion accumulated in the planted beds corresponding to the TCE loss, suggesting that contaminant dehalogenation was the primary loss fate.

Whitebark pine diameter growth response to removal of competition

Treesearch

Robert E. Keane; Kathy L. Gray; Laura J. Dickinson

2007-01-01

Silvicultural cutting treatments may be needed to restore whitebark pine (Pinus albicaulis) forests, but little is known of the response of this species to removal of competition through prescribed burning or silvicultural cuttings. We analyzed stem cross-sections from 48 whitebark pine trees in Montana around which most of the competing vegetation...

Prediction and error of baldcypress stem volume from stump diameter

Treesearch

Bernard R. Parresol

1998-01-01

The need to estimate the volume of removals occurs for many reasons, such as in trespass cases, severance tax reports, and post-harvest assessments. A logarithmic model is presented for prediction of baldcypress total stem cubic foot volume using stump diameter as the independent variable. Because the error of prediction is as important as the volume estimate, the...

Nutrients: a major consideration in intensive forest management

Treesearch

James W. Hornbeck

1977-01-01

Estimates of nutrient losses are compared for stem-only harvest versus a whole-tree harvest of a clearcut northern hardwood stand. Combined nutrient losses due to increased leaching and removal of vegetation after stem-only harvesting are estimated to be 334 kg/ha for calcium and 265 kg/ha for nitrogen. For a whole-tree harvest, combined losses are estimated at 537 kg/...

Two Years Necessary for Successful Natural Seeding in Nonbrushy Black Spruce Bogs

Treesearch

Elon S. Verry; Arthur E. Elling

1978-01-01

Natural seeding in a strip-cut black spruce bog was adequate, averaging 1,800 stems per acre and 80 percent milacre stocking. natural seeding in a completely cut bog was inadequate, averaging 630 stems per acre and 40 percent milacre stocking. Slash was removed to expose sphagnum seedbeds in both cases. Progressive cutting every other year is recommended.

High tonnage harvesting and skidding for loblolly pine energy plantations

Treesearch

Patrick Jernigan; Tom Gallagher; Dana Mitchell; Mathew Smidt; Larry Teeter

2016-01-01

The southeastern United States has a promising source for renewable energy in the form of woody biomass. To meet the energy needs, energy plantations will likely be utilized. These plantations will contain a high density of small-stem pine trees. Since the stems are relatively small when compared with traditional product removal, the harvesting costs will increase. The...

Clinical application prospect of umbilical cord-derived mesenchymal stem cells on clearance of advanced glycation end products through autophagy on diabetic wound.

PubMed

Han, Yanfu; Sun, Tianjun; Tao, Ran; Han, Yanqing; Liu, Jing

2017-03-24

Nowadays, wound healing delay due to diabetes is considered to be closely related to the accumulation of advanced glycation end products (AGEs). Although mesenchymal stem cells (MSCs) exhibit positive effects on diabetic wound healing, related mechanisms are still not fully elucidated. It has been reported that MSCs can improve the activity of autophagy in injured tissues, thereby playing an important role in wound healing. The autophagy induced by MSCs may be beneficial to diabetic wound healing via removing AGEs, which provide new ideas for clinical treatment of diabetic wounds with the potential of broad application prospects. In this study, the current research situation and application prospect of umbilical cord-derived MSCs on the clearance of AGEs in diabetic wound were reviewed.

Chondroitin sulfate effects on neural stem cell differentiation.

PubMed

Canning, David R; Brelsford, Natalie R; Lovett, Neil W

2016-01-01

We have investigated the role chondroitin sulfate has on cell interactions during neural plate formation in the early chick embryo. Using tissue culture isolates from the prospective neural plate, we have measured neural gene expression profiles associated with neural stem cell differentiation. Removal of chondroitin sulfate from stage 4 neural plate tissue leads to altered associations of N-cadherin-positive neural progenitors and causes changes in the normal sequence of neural marker gene expression. Absence of chondroitin sulfate in the neural plate leads to reduced Sox2 expression and is accompanied by an increase in the expression of anterior markers of neural regionalization. Results obtained in this study suggest that the presence of chondroitin sulfate in the anterior chick embryo is instrumental in maintaining cells in the neural precursor state.

Aberration-Corrected STEM Imaging Through Off-Site Remote Operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarvis, Karalee; Allard Jr, Lawrence Frederick; Jerome, Timothy Y

2010-01-01

Recent advances in aberration-corrected electron microscopy have allowed researchers to image materials at sub- ngstr m resolution. Many of these modern instruments are designed to be operated from separate 'control' rooms, removing the effect of the operator on the instrument s physical environment. This capability also allows operation from suitable workstations, over internet connections, from literally anywhere in the world [1]. Researchers at the University of Texas at Austin (UTA) have collaborated with Oak Ridge National Laboratory (ORNL) and JEOL Ltd. to routinely conduct research sessions in which high-resolution images and X-ray microanalytical data are acquired during after-hours research sessions,more » utilizing the JEOL 2200FS aberration-corrected STEM/TEM at ORNL from their lab in Austin. Details of the remote operation are presented here.« less

Rapid fibroblast removal from high density human embryonic stem cell cultures.

PubMed

Turner, William S; McCloskey, Kara E

2012-10-28

Mouse embryonic fibroblasts (MEFs) were used to establish human embryonic stem cells (hESCs) cultures after blastocyst isolation(1). This feeder system maintains hESCs from undergoing spontaneous differentiation during cell expansion. However, this co-culture method is labor intensive, requires highly trained personnel, and yields low hESC purity(4). Many laboratories have attempted to minimize the number of feeder cells in hESC cultures (i.e. incorporating matrix-coated dishes or other feeder cell types(5-8)). These modified culture systems have shown some promise, but have not supplanted the standard method for culturing hESCs with mitomycin C-treated mouse embyronic fibroblasts in order to retard unwanted spontaneous differentiation of the hESC cultures. Therefore, the feeder cells used in hESC expansion should be removed during differentiation experiments. Although several techniques are available for purifying the hESC colonies (FACS, MACS, or use of drug resistant vectors) from feeders, these techniques are labor intensive, costly and/or destructive to the hESC. The aim of this project was to invent a method of purification that enables the harvesting of a purer population of hESCs. We have observed that in a confluent hESC culture, the MEF population can be removed using a simple and rapid aspiration of the MEF sheet. This removal is dependent on several factors, including lateral cell-to-cell binding of MEFs that have a lower binding affinity to the styrene culture dish, and the ability of the stem cell colonies to push the fibroblasts outward during the generation of their own "niche". The hESC were then examined for SSEA-4, Oct3/4 and Tra 1-81 expression up to 10 days after MEF removal to ensure maintenance of pluripotency. Moreover, hESC colonies were able to continue growing from into larger formations after MEF removal, providing an additional level of hESC expansion.

Imatinib-loaded polyelectrolyte microcapsules for sustained targeting of BCR-ABL+ leukemia stem cells.

PubMed

Palamà, Ilaria E; Leporatti, Stefano; de Luca, Emanuela; Di Renzo, Nicola; Maffia, Michele; Gambacorti-Passerini, Carlo; Rinaldi, Ross; Gigli, Giuseppe; Cingolani, Roberto; Coluccia, Addolorata M L

2010-04-01

The lack of sensitivity of chronic myeloid leukemia (CML) stem cells to imatinib mesylate (IM) commonly leads to drug dose escalation or early disease relapses when therapy is stopped. Here, we report that packaging of IM into a biodegradable carrier based on polyelectrolyte microcapsules increases drug retention and antitumor activity in CML stem cells, also improving the ex vivo purging of malignant progenitors from patient autografts. Microparticles/capsules were obtained by layer-by-layer (LbL) self-assembly of oppositely charged polyelectrolyte multilayers on removable calcium carbonate (CaCO(3)) templates and loaded with or without IM. A leukemic cell line (KU812) and CD34(+) cells freshly isolated from healthy donors or CML patients were tested. Polyelectrolyte microcapsules (PMCs) with an average diameter of 3 microm, fluorescently labelled multilayers sensitive to the action of intracellular proteases and 95-99% encapsulation efficiency of IM, were prepared. Cell uptake efficiency of such biodegradable carriers was quantified in KU812, leukemic and normal CD34(+) stem cells (range: 70-85%), and empty PMCs did not impact cell viability. IM-loaded PMCs selectively targeted CML cells, by promoting apoptosis at doses that exert only cytostatic effects by IM alone. More importantly, residual CML cells from patient leukapheresis products were reduced or eliminated more efficiently by using IM-loaded PMCs compared with freely soluble IM, with a purging efficiency of several logs. No adverse effects on normal CD34(+) stem-cell survival and their clonogenic potential was noticed in long-term cultures of hematopoietic progenitors in vitro. This pilot study provides the proof-of-principle for the clinical application of biodegradable IM-loaded PMC as feasible, safe and effective ex vivo purging agents to target CML stem cells, in order to improve transplant outcome of resistant/relapsed patients or reduce IM dose escalation.

Pomegranate MR images analysis using ACM and FCM algorithms

NASA Astrophysics Data System (ADS)

Morad, Ghobad; Shamsi, Mousa; Sedaaghi, M. H.; Alsharif, M. R.

2011-10-01

Segmentation of an image plays an important role in image processing applications. In this paper segmentation of pomegranate magnetic resonance (MR) images has been explored. Pomegranate has healthy nutritional and medicinal properties for which the maturity indices and quality of internal tissues play an important role in the sorting process in which the admissible determination of features mentioned above cannot be easily achieved by human operator. Seeds and soft tissues are the main internal components of pomegranate. For research purposes, such as non-destructive investigation, in order to determine the ripening index and the percentage of seeds in growth period, segmentation of the internal structures should be performed as exactly as possible. In this paper, we present an automatic algorithm to segment the internal structure of pomegranate. Since its intensity of stem and calyx is close to the internal tissues, the stem and calyx pixels are usually labeled to the internal tissues by segmentation algorithm. To solve this problem, first, the fruit shape is extracted from its background using active contour model (ACM). Then stem and calyx are removed using morphological filters. Finally the image is segmented by fuzzy c-means (FCM). The experimental results represent an accuracy of 95.91% in the presence of stem and calyx, while the accuracy of segmentation increases to 97.53% when stem and calyx are first removed by morphological filters.

Eye Absence Does Not Regulate Planarian Stem Cells during Eye Regeneration.

PubMed

LoCascio, Samuel A; Lapan, Sylvain W; Reddien, Peter W

2017-02-27

Dividing cells called neoblasts contain pluripotent stem cells and drive planarian flatworm regeneration from diverse injuries. A long-standing question is whether neoblasts directly sense and respond to the identity of missing tissues during regeneration. We used the eye to investigate this question. Surprisingly, eye removal was neither sufficient nor necessary for neoblasts to increase eye progenitor production. Neoblasts normally increase eye progenitor production following decapitation, facilitating regeneration. Eye removal alone, however, did not induce this response. Eye regeneration following eye-specific resection resulted from homeostatic rates of eye progenitor production and less cell death in the regenerating eye. Conversely, large head injuries that left eyes intact increased eye progenitor production. Large injuries also non-specifically increased progenitor production for multiple uninjured tissues. We propose a model for eye regeneration in which eye tissue production by planarian stem cells is not directly regulated by the absence of the eye itself. Copyright © 2017 Elsevier Inc. All rights reserved.

Brain Stem Cavernous Malformations: Operative Nuances of a Less-Invasive Resection Technique.

PubMed

Singh, Harminder; Elarjani, Turki; da Silva, Harley Brito; Shetty, Rakshith; Kim, Louis; Sekhar, Laligam N

2017-12-08

Different operative techniques are reported for the resection of brainstem cavernous malformations (BSCMs). The senior author has previously reported on a less-invasive technique of entering the brain stem with piecemeal removal of BSCMs, especially the deep-seated ones. To present a larger series of these lesions, emphasizing the approach to the brain stem via case selection. We discuss the nuances of the less-invasive operative technique through case illustrations and intraoperative videos. A retrospective review of 46 consecutive cases of BSCMs, with their clinical and radiographic data, was performed. Nine cases were selected to illustrate 7 different operative approaches, and discuss surgical nuances of the less-invasive technique unique to each. Postoperative morbidity, defined as an increase in modified Rankin Scale, was observed in 5 patients (10.9%). A residual BSCM was present in 2 patients (4.3%); both underwent reoperation to remove the remainder. At follow-up of 31.1 ± 27.8 mo, 3 patients experienced recurrence (6.5%). Overall, 65% of our patients improved, 20% stayed the same, and 11% worsened postsurgery. Two patients died, yielding a mortality of 4.3%. Using the less-invasive resection technique for piecemeal BSCM removal, in appropriately selected patients, has yielded comparable to improved patient outcomes over existing large series. In our experience, lateral, anterolateral, and posterolateral approaches are favorable over direct midline (dorsal or ventral) approaches. A thorough understanding of brain-stem safe-entry zones, in conjunction with appropriate approach selection, is key to a good outcome in challenging cases. Copyright © 2017 by the Congress of Neurological Surgeons

Initial responses of rove and ground beetles (Coleoptera, Staphylinidae, Carabidae) to removal of logging residues following clearcut harvesting in the boreal forest of Quebec, Canada

PubMed Central

Work, Timothy T.; Klimaszewski, Jan; Thiffault, Evelyne; Bourdon, Caroline; Paré, David; Bousquet, Yves; Venier, Lisa; Titus, Brian

2013-01-01

Abstract Increased interest in biomass harvesting for bioenergetic applications has raised questions regarding the potential ecological consequences on forest biodiversity. Here we evaluate the initial changes in the abundance, species richness and community composition of rove (Staphylinidae) and ground beetles (Carabidae), immediately following 1) stem-only harvesting (SOH), in which logging debris (i.e., tree tops and branches) are retained on site, and 2) whole-tree harvesting (WTH), in which stems, tops and branches are removed in mature balsam fir stands in Quebec, Canada. Beetles were collected throughout the summer of 2011, one year following harvesting, using pitfall traps. Overall catch rates were greater in uncut forest (Control) than either stem-only or whole-tree harvested sites. Catch rates in WTH were greater than SOH sites. Uncut stands were characterized primarily by five species: Atheta capsularis, Atheta klagesi, Atheta strigosula, Tachinus fumipennis/frigidus complex (Staphylinidae) and to a lesser extent to Pterostichus punctatissimus (Carabidae). Increased catch rates in WTH sites, where post-harvest biomass was less, were attributable to increased catches of rove beetles Pseudopsis subulata, Quedius labradorensis and to a lesser extent Gabrius brevipennis. We were able to characterize differences in beetle assemblages between harvested and non-harvested plots as well as differences between whole tree (WTH) and stem only (SOH) harvested sites where logging residues had been removed or left following harvest. However, the overall assemblage response was largely a recapitulation of the responses of several abundant species. PMID:23653498

Initial responses of rove and ground beetles (Coleoptera, Staphylinidae, Carabidae) to removal of logging residues following clearcut harvesting in the boreal forest of Quebec, Canada.

PubMed

Work, Timothy T; Klimaszewski, Jan; Thiffault, Evelyne; Bourdon, Caroline; Paré, David; Bousquet, Yves; Venier, Lisa; Titus, Brian

2013-01-01

Increased interest in biomass harvesting for bioenergetic applications has raised questions regarding the potential ecological consequences on forest biodiversity. Here we evaluate the initial changes in the abundance, species richness and community composition of rove (Staphylinidae) and ground beetles (Carabidae), immediately following 1) stem-only harvesting (SOH), in which logging debris (i.e., tree tops and branches) are retained on site, and 2) whole-tree harvesting (WTH), in which stems, tops and branches are removed in mature balsam fir stands in Quebec, Canada. Beetles were collected throughout the summer of 2011, one year following harvesting, using pitfall traps. Overall catch rates were greater in uncut forest (Control) than either stem-only or whole-tree harvested sites. Catch rates in WTH were greater than SOH sites. Uncut stands were characterized primarily by five species: Atheta capsularis, Atheta klagesi, Atheta strigosula, Tachinus fumipennis/frigidus complex (Staphylinidae) and to a lesser extent to Pterostichus punctatissimus(Carabidae). Increased catch rates in WTH sites, where post-harvest biomass was less, were attributable to increased catches of rove beetles Pseudopsis subulata, Quedius labradorensis and to a lesser extent Gabrius brevipennis. We were able to characterize differences in beetle assemblages between harvested and non-harvested plots as well as differences between whole tree (WTH) and stem only (SOH) harvested sites where logging residues had been removed or left following harvest. However, the overall assemblage response was largely a recapitulation of the responses of several abundant species.

How young trees cope with removal of whole or parts of shoots: an analysis of local and distant responses to pruning in 1-year-old apple (Malus xdomestica; Rosaceae) trees.

PubMed

Fumey, Damien; Lauri, Pierre-Éric; Guédon, Yann; Godin, Christophe; Costes, Evelyne

2011-11-01

Manipulation of tree architecture by pruning provides an experimental context to analyze architectural plasticity resulting from competition between developing organs. The objective of this study was to quantify the effects of the removal of all or part of shoots through pruning on the redistribution of growth and flowering at spatial and temporal levels. Two types of pruning cuts were applied: (1) heading cuts of either the main stem or laterals and (2) thinning cuts (i.e., complete removal) of laterals. These two types of cuts were applied in summer and winter on 1-yr-old cultivars of Fuji and Braeburn apple trees. Tree topology and geometry were described over 3 years, and responses were analyzed for both local and distant scales. Heading cuts induced quasi-deterministic local responses on pruned axes, whereas responses to thinning cuts were more variable. For the main stem and laterals, responses over greater spatial and temporal scales were highlighted with (1) stronger growth the year after summer pruning and (2) modification of branching and flowering along the unpruned parts after winter pruning. Pruning typically induced growth redistribution toward traumatic reiterations and enhanced growth of the remaining unpruned axes with a concomitant decrease of flowering and cambial growth. Although results could be interpreted in relation to the root-shoot balance, tree responses appeared highly cultivar-specific.

Fiber lengths in stems and branches of small hardwoods on southern pine sites

Treesearch

F. G. Manwiller

1974-01-01

The 22 species selected for analysis comprise over 95 percent of the hardwood volume occurring on pine sites. Ten trees 6 inch. in diameter at breast height (DBH) of each species were taken from throughout that portion of the species' range occurring in the South. Pie-shaped wedges, removed at 48-inch intervals along the stem and each branch, were combined within...

Fiber lengths in stems and brances of small hardwoods on southern pine sites

Treesearch

Floyd G. Manwiller

1974-01-01

The 22 species selected for analysis comprise over 95 percent of the hardwood volume occurring on pine sites. Ten trees 6 inches in diameter at breast height (DBH) of each species were taken from throughout that portion of the spcies' range occurring in the South. Pie-shaped wedges, removed at 48-inch intervals along the stem and each branch, were combined within...

Unique competitive effects of lianas and trees in a tropical forest understory.

PubMed

Wright, Alexandra; Tobin, Mike; Mangan, Scott; Schnitzer, Stefan A

2015-02-01

Lianas are an important component of tropical forests, contributing up to 25% of the woody stems and 35% of woody species diversity. Lianas invest less in structural support but more in leaves compared to trees of similar biomass. These physiological and morphological differences suggest that lianas may interact with neighboring plants in ways that are different from similarly sized trees. However, the vast majority of past liana competition studies have failed to identify the unique competitive effects of lianas by controlling for the amount of biomass removed. We assessed liana competition in the forest understory over the course of 3 years by removing liana biomass and an equal amount of tree biomass in 40 plots at 10 sites in a secondary tropical moist forest in central Panama. We found that growth of understory trees and lianas, as well as planted seedlings, was limited due to competitive effects from both lianas and trees, though the competitive impacts varied by species, season, and size of neighbors. The removal of trees resulted in greater survival of planted seedlings compared to the removal of lianas, apparently related to a greater release from competition for light. In contrast, lianas had a species-specific negative effect on drought-tolerant Dipteryx oleifera seedlings during the dry season, potentially due to competition for water. We conclude that, at local scales, lianas and trees have unique and differential effects on understory dynamics, with lianas potentially competing more strongly during the dry season, and trees competing more strongly for light.

Intramedullary Stabilization of Periprosthetic Fractures of the Femur Taking Special Account of Bone Defects.

PubMed

Eingartner, Christoph; Volkmann, Rüdiger; Ochs, Uwe; Egetemeyr, Daniel; Weise, Kuno

2007-10-01

Healing of the periprosthetic fracture and area of defective bone by the bone healing mechanisms of intramedullary stabilization. Reconstruction of the correct length, axial alignment, and rotation of the fractured femoral shaft by anchoring a revision stem in the intact femoral diaphysis. Periprosthetic femoral shaft fracture in the region of the prosthetic stem combined with preexistent loosening and/or defect in the periprosthetic bone bed (Vancouver classification type B2 and B3). General contraindications, local infection. Lateral transmuscular approach to the femoral shaft. Longitudinal osteotomy of the proximal femur taking the geometry of the fracture into account. Opening of an anterior "bone shell". Removal of the loose prosthetic stem and cement. Debridement. Preparation of the femoral diaphysis and insertion of a distally anchored revision stem. Distal locking. Repositioning of the "bone shell", reduction of the fracture, and retention with cerclage wires. Bed rest for approximately 1 week, mobilization with 20 kg partial weight bearing for 12 weeks, gradual increase in weight bearing with radiologic checks on progress, removal of the distal locking bolts after 12-24 months at the earliest. 21 patients (13 women, eight men) aged between 43 and 86 years (mean age: 71.2 years) with periprosthetic fracture of the femur, additional loosening of the stem in eight cases (Vancouver B2) and additional bone loss in 13 cases (Vancouver B3). Postoperative complications: two fractures following another fall (repeat operations: one replacement, one plate), four revisions due to subsidence of the stem (three replacements involving change to a standard stem with healed proximal femur, one replacement with another interlocked revision stem). Bone healing occurred for all fractures after a mean 5.6 months (3-11 months). Follow- up examination after a mean 4.5 years: all patients were able to walk, average Harris Score 70.5 points (29- 95 points).

Intramedullary stabilization of periprosthetic fractures of the femur taking special account of bone defects.

PubMed

Eingartner, Christoph; Volkmann, Rüdiger; Ochs, Uwe; Egetemeyr, Daniel; Weise, Kuno

2006-10-01

Healing of the periprosthetic fracture and area of defective bone by the bone healing mechanisms of intramedullary stabilization. Reconstruction of the correct length, axial alignment, and rotation of the fractured femoral shaft by anchoring a revision stem in the intact femoral diaphysis. Periprosthetic femoral shaft fracture in the region of the prosthetic stem combined with preexistent loosening and/or defect in the periprosthetic bone bed (Vancouver classification type B2 and B3). General contraindications, local infection. Lateral transmuscular approach to the femoral shaft. Longitudinal osteotomy of the proximal femur taking the geometry of the fracture into account. Opening of an anterior "bone shell". Removal of the loose prosthetic stem and cement. Debridement. Preparation of the femoral diaphysis and insertion of a distally anchored revision stem. Distal locking. Repositioning of the "bone shell", reduction of the fracture, and retention with cerclage wires. Bed rest for approximately 1 week, mobilization with 20 kg partial weight bearing for 12 weeks, gradual increase in weight bearing with radiologic checks on progress, removal of the distal locking bolts after 12-24 months at the earliest. 21 patients (13 women, eight men) aged between 43 and 86 years (mean age: 71.2 years) with periprosthetic fracture of the femur, additional loosening of the stem in eight cases (Vancouver B2) and additional bone loss in 13 cases (Vancouver B3). Postoperative complications: two fractures following another fall (repeat operations: one replacement, one plate), four revisions due to subsidence of the stem (three replacements involving change to a standard stem with healed proximal femur, one replacement with another interlocked revision stem). Bone healing occurred for all fractures after a mean 5.6 months (3-11 months). Follow-up examination after a mean 4.5 years: all patients were able to walk, average Harris Score 70.5 points (29-95 points).

Leak test adapter for containers

DOEpatents

Hallett, Brian H.; Hartley, Michael S.

1996-01-01

An adapter is provided for facilitating the charging of containers and leak testing penetration areas. The adapter comprises an adapter body and stem which are secured to the container's penetration areas. The container is then pressurized with a tracer gas. Manipulating the adapter stem installs a penetration plug allowing the adapter to be removed and the penetration to be leak tested with a mass spectrometer. Additionally, a method is provided for using the adapter.

AutoMap User’s Guide

DTIC Science & Technology

2006-10-01

Hierarchy of Pre-Processing Techniques 3. NLP (Natural Language Processing) Utilities 3.1 Named-Entity Recognition 3.1.1 Example for Named-Entity... Recognition 3.2 Symbol RemovalN-Gram Identification: Bi-Grams 4. Stemming 4.1 Stemming Example 5. Delete List 5.1 Open a Delete List 5.1.1 Small...iterative and involves several key processes: • Named-Entity Recognition Named-Entity Recognition is an Automap feature that allows you to

A Comparison of Oak Regeneration Conditions Following Midstory Injection and Partial Overstory Removal in a Tombigbee River Terrace

Treesearch

Stephen E. Peairs; Andrew W. Ezell; Keith L. Belli; John D. Hodges

2004-01-01

Bottomland hardwood stands comprised of a large oak component can be regenerated through natural oak regeneration. To maximize oak regeneration potential, the stand manager must practice silvicultural techniques that allow for necessary sunlight penetration to reach the forest floor. Control of stems occupying the midstory/understory and partial overstory removal are...

Purification of human induced pluripotent stem cell-derived neural precursors using magnetic activated cell sorting.

PubMed

Rodrigues, Gonçalo M C; Fernandes, Tiago G; Rodrigues, Carlos A V; Cabral, Joaquim M S; Diogo, Maria Margarida

2015-01-01

Neural precursor (NP) cells derived from human induced pluripotent stem cells (hiPSCs), and their neuronal progeny, will play an important role in disease modeling, drug screening tests, central nervous system development studies, and may even become valuable for regenerative medicine treatments. Nonetheless, it is challenging to obtain homogeneous and synchronously differentiated NP populations from hiPSCs, and after neural commitment many pluripotent stem cells remain in the differentiated cultures. Here, we describe an efficient and simple protocol to differentiate hiPSC-derived NPs in 12 days, and we include a final purification stage where Tra-1-60+ pluripotent stem cells (PSCs) are removed using magnetic activated cell sorting (MACS), leaving the NP population nearly free of PSCs.

The effect of mesenchymal stem cells combined with platelet-rich plasma on skin wound healing.

PubMed

Mahmoudian-Sani, Mohammad-Reza; Rafeei, Fatemeh; Amini, Razieh; Saidijam, Massoud

2018-03-04

Mesenchymal stem cells (MSCs) are multipotent stem cells that have the potential of proliferation, high self-renewal, and the potential of multilineage differentiation. The differentiation potential of the MSCs in vivo and in vitro has caused these cells to be regarded as potentially appropriate tools for wound healing. After the burn, trauma or removal of the tumor of wide wounds is developed. Although standard treatment for skin wounds is primary healing or skin grafting, they are not always practical mainly because of limited autologous skin grafting. Directory of Open Access Journals (DOAJ), Google Scholar, PubMed (NLM), LISTA (EBSCO), and Web of Science have been searched. For clinical use of the MSCs in wound healing, two key issues should be taken into account: First, engineering biocompatible scaffolds clinical use of which leads to the least amount of side effects without any immunologic response and secondly, use of stem cells secretions with the least amount of clinical complications despite their high capability of healing damage. In light of the MSCs' high capability of proliferation and multilineage differentiation as well as their significant role in modulating immunity, these cells can be used in combination with tissue engineering techniques. Moreover, the MSCs' secretions can be used in cell therapy to heal many types of wounds. The combination of MSCs and PRP aids wound healing which could potentially be used to promote wound healing. © 2018 Wiley Periodicals, Inc.

Scalable 96-well Plate Based iPSC Culture and Production Using a Robotic Liquid Handling System.

PubMed

Conway, Michael K; Gerger, Michael J; Balay, Erin E; O'Connell, Rachel; Hanson, Seth; Daily, Neil J; Wakatsuki, Tetsuro

2015-05-14

Continued advancement in pluripotent stem cell culture is closing the gap between bench and bedside for using these cells in regenerative medicine, drug discovery and safety testing. In order to produce stem cell derived biopharmaceutics and cells for tissue engineering and transplantation, a cost-effective cell-manufacturing technology is essential. Maintenance of pluripotency and stable performance of cells in downstream applications (e.g., cell differentiation) over time is paramount to large scale cell production. Yet that can be difficult to achieve especially if cells are cultured manually where the operator can introduce significant variability as well as be prohibitively expensive to scale-up. To enable high-throughput, large-scale stem cell production and remove operator influence novel stem cell culture protocols using a bench-top multi-channel liquid handling robot were developed that require minimal technician involvement or experience. With these protocols human induced pluripotent stem cells (iPSCs) were cultured in feeder-free conditions directly from a frozen stock and maintained in 96-well plates. Depending on cell line and desired scale-up rate, the operator can easily determine when to passage based on a series of images showing the optimal colony densities for splitting. Then the necessary reagents are prepared to perform a colony split to new plates without a centrifugation step. After 20 passages (~3 months), two iPSC lines maintained stable karyotypes, expressed stem cell markers, and differentiated into cardiomyocytes with high efficiency. The system can perform subsequent high-throughput screening of new differentiation protocols or genetic manipulation designed for 96-well plates. This technology will reduce the labor and technical burden to produce large numbers of identical stem cells for a myriad of applications.

Removal of well-fixed components in femoral revision arthroplasty with controlled segmentation of the proximal femur.

PubMed

Megas, Panagiotis; Georgiou, Christos S; Panagopoulos, Andreas; Kouzelis, Antonis

2014-12-31

The transfemoral and the extended trochanteric osteotomies are the most common osteotomies used in femoral revision, both when proximal or diaphyseal fixation of the new component has been decided. We present an alternative approach to the trochanteric osteotomies, most frequently used with distally fixated stems, to overcome their shortcomings of osteotomy migration and nonunion, but, most of all, the uncontrollable fragmentation of the femur. The procedure includes a complete circular femoral osteotomy just below the stem tip to prevent distal fracture propagation and a subsequent preplanned segmentation of the proximal femur for better exposure and fast removal of the old prosthesis. The bone fragments are reattached with cerclage wires to the revision prosthesis, which is safely anchored distally. A modified posterolateral approach is used, as the preservation of the continuity of the abductors, the greater trochanter, and the vastus lateralis is a prerequisite. Between 2006 and 2012, 47 stems (33 women, 14 men, mean age 68 years, range 39-88 years) were revised using this technique. They were 12 (26%) stable and 35 (74%) loose prostheses and were all revised to tapered, fluted, grit-blasted stems. No fracture of the trochanters or the distal femur occurred intraoperatively. Mean follow-up was 28 months (range 6-70 months). No case of trochanteric migration or nonunion of the osteotomies was recorded. Restoration of the preexisting bone defects occurred in 83% of the patients. Three patients required repeat revision due to dislocation and one due to a postoperative periprosthetic fracture. None of the failures was attributed to the procedure itself. This new osteotomy technique may seem aggressive at first, but, at least in our hands, has effectively increased the speed of the femoral revision, particularly for the most difficult well-fixed components, but not at the expense of safety.

Culture in embryonic kidney serum and xeno-free media as renal cell carcinoma and renal cell carcinoma cancer stem cells research model.

PubMed

Krawczyk, Krzysztof M; Matak, Damian; Szymanski, Lukasz; Szczylik, Cezary; Porta, Camillo; Czarnecka, Anna M

2018-04-01

The use of fetal bovine serum hinders obtaining reproducible experimental results and should also be removed in hormone and growth factor studies. In particular hormones found in FBS act globally on cancer cell physiology and influence transcriptome and metabolome. The aim of our study was to develop a renal carcinoma serum free culture model optimized for (embryonal) renal cells in order to select the best study model for downstream auto-, para- or endocrine research. Secondary aim was to verify renal carcinoma stem cell culture for this application. In the study, we have cultured renal cell carcinoma primary tumour cell line (786-0) as well as human kidney cancer stem cells in standard 2D monolayer cultures in Roswell Park Memorial Institute Medium or Dulbecco's Modified Eagle's Medium and Complete Human Kidney Cancer Stem Cell Medium, respectively. Serum-free, animal-component free Human Embryonic Kidney 293 media were tested. Our results revealed that xeno-free embryonal renal cells optimized culture media provide a useful tool in RCC cancer biology research and at the same time enable effective growth of RCC. We propose bio-mimic RCC cell culture model with specific serum-free and xeno-free medium that promote RCC cell viability.

Correlative Electron and Fluorescence Microscopy of Magnetotactic Bacteria in Liquid: Toward In Vivo Imaging

PubMed Central

Woehl, Taylor J.; Kashyap, Sanjay; Firlar, Emre; Perez-Gonzalez, Teresa; Faivre, Damien; Trubitsyn, Denis; Bazylinski, Dennis A.; Prozorov, Tanya

2014-01-01

Magnetotactic bacteria biomineralize ordered chains of uniform, membrane-bound magnetite or greigite nanocrystals that exhibit nearly perfect crystal structures and species-specific morphologies. Transmission electron microscopy (TEM) is a critical technique for providing information regarding the organization of cellular and magnetite structures in these microorganisms. However, conventional TEM can only be used to image air-dried or vitrified bacteria removed from their natural environment. Here we present a correlative scanning TEM (STEM) and fluorescence microscopy technique for imaging viable cells of Magnetospirillum magneticum strain AMB-1 in liquid using an in situ fluid cell TEM holder. Fluorescently labeled cells were immobilized on microchip window surfaces and visualized in a fluid cell with STEM, followed by correlative fluorescence imaging to verify their membrane integrity. Notably, the post-STEM fluorescence imaging indicated that the bacterial cell wall membrane did not sustain radiation damage during STEM imaging at low electron dose conditions. We investigated the effects of radiation damage and sample preparation on the bacteria viability and found that approximately 50% of the bacterial membranes remained intact after an hour in the fluid cell, decreasing to ~30% after two hours. These results represent a first step toward in vivo studies of magnetite biomineralization in magnetotactic bacteria. PMID:25358460

Correlative Electron and Fluorescence Microscopy of Magnetotactic Bacteria in Liquid: Toward In Vivo Imaging

DOE PAGES

Woehl, Taylor J.; Kashyap, Sanjay; Firlar, Emre; ...

2014-10-31

Magnetotactic bacteria biomineralize ordered chains of uniform, membrane-bound magnetite or greigite nanocrystals that exhibit nearly perfect crystal structures and species-specific morphologies. Transmission electron microscopy (TEM) is a critical technique for providing information regarding the organization of cellular and magnetite structures in these microorganisms. However, conventional TEM can only be used to image air-dried or vitrified bacteria removed from their natural environment. Here we present a correlative scanning TEM (STEM) and fluorescence microscopy technique for imaging viable cells of Magnetospirillum magneticum strain AMB-1 in liquid using an in situ fluid cell TEM holder. Fluorescently labeled cells were immobilized on microchip windowmore » surfaces and visualized in a fluid cell with STEM, followed by correlative fluorescence imaging to verify their membrane integrity. Notably, the post-STEM fluorescence imaging indicated that the bacterial cell wall membrane did not sustain radiation damage during STEM imaging at low electron dose conditions. We investigated the effects of radiation damage and sample preparation on the bacteria viability and found that approximately 50% of the bacterial membranes remained intact after an hour in the fluid cell, decreasing to ~30% after two hours. These results represent a first step toward in vivo studies of magnetite biomineralization in magnetotactic bacteria.« less

TH-CD-BRA-12: Impact of a Magnetic Field On the Response From a Plastic Scintillation Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Therriault-Proulx, F; Wen, Z; Ibbott, G

Purpose: To study the effect of a strong magnetic field on the scintillation and the stem effect from a plastic scintillation detector (PSD) and evaluate its accuracy to measure dose. Methods: A plastic scintillation detector and a bare plastic fiber were placed inside a magnet of adjustable field strength (B=0−1.5T) and irradiated by a 6-MV photon beam (Elekta Versa HD LINAC). The PSD was built in-house using a scintillating fiber (BCF-60, 3-mm long × 1-mm diameter) coupled to an optical fiber similar to the bare fiber (PMMA, 12-m long, 1-mm diameter). Light output spectra were acquired with a spectrometer. Intensitymore » and shape of the output spectra were compared as a function of the magnetic field strength. The bare fiber was used to study the behavior of the stem effect (composed of Cerenkov and fluorescence). The spectrometry setup allowed to perform a previously demonstrated hyperspectral stem-effect removal and calculated dose was studied as a function of the magnetic field strength. Results: Signal intensities were shown to increase with the magnetic field strength by up to 19% and 79% at 1.5T in comparison to the irradiation without a magnetic field, for respectively the PSD and the bare fiber. The light produced by Cerenkov effect in the optical fiber was shown to be the major component affected by the magnetic field. Effect of the magnetic field on the electrons trajectory may explain this behavior. Finally, accounting for the stem effect using the hyperspectral approach led to accuracy in dose measurement within 2.6%. Interestingly, variations in accuracy were negligible for values over 0.3T. Conclusion: Dependence of PSDs to magnetic field is mainly due to the Cerenkov light. When accounting for it, PSDs become a candidate of choice for both quality assurance and in vivo dosimetry of therapy under strong magnetic fields (e.g. for MRI-Linacs).« less

Concise Review: Kidney Stem/Progenitor Cells: Differentiate, Sort Out, or Reprogram?

PubMed Central

Pleniceanu, Oren; Harari-Steinberg, Orit; Dekel, Benjamin

2010-01-01

End-stage renal disease (ESRD) is defined as the inability of the kidneys to remove waste products and excess fluid from the blood. ESRD progresses from earlier stages of chronic kidney disease (CKD) and occurs when the glomerular filtration rate (GFR) is below 15 ml/minute/1.73 m2. CKD and ESRD are dramatically rising due to increasing aging population, population demographics, and the growing rate of diabetes and hypertension. Identification of multipotential stem/progenitor populations in mammalian tissues is important for therapeutic applications and for understanding developmental processes and tissue homeostasis. Progenitor populations are ideal targets for gene therapy, cell transplantation, and tissue engineering. The demand for kidney progenitors is increasing due to severe shortage of donor organs. Because dialysis and transplantation are currently the only successful therapies for ESRD, cell therapy offers an alternative approach for kidney diseases. However, this approach may be relevant only in earlier stages of CKD, when kidney function and histology are still preserved, allowing for the integration of cells and/or for their paracrine effects, but not when small and fibrotic end-stage kidneys develop. Although blood- and bone marrow-derived stem cells hold a therapeutic promise, they are devoid of nephrogenic potential, emphasizing the need to seek kidney stem cells beyond known extrarenal sources. Moreover, controversies regarding the existence of a true adult kidney stem cell highlight the importance of studying cell-based therapies using pluripotent cells, progenitor cells from fetal kidney, or dedifferentiated/reprogrammed adult kidney cells. Stem Cells 2010; 28:1649–1660. PMID:20652959

Transcript Lifetime Is Balanced between Stabilizing Stem-Loop Structures and Degradation-Promoting Polyadenylation in Plant Mitochondria

PubMed Central

Kuhn, Josef; Tengler, Ulrike; Binder, Stefan

2001-01-01

To determine the influence of posttranscriptional modifications on 3′ end processing and RNA stability in plant mitochondria, pea atp9 and Oenothera atp1 transcripts were investigated for the presence and function of 3′ nonencoded nucleotides. A 3′ rapid amplification of cDNA ends approach initiated at oligo(dT)-adapter primers finds the expected poly(A) tails predominantly attached within the second stem or downstream of the double stem-loop structures at sites of previously mapped 3′ ends. Functional studies in a pea mitochondrial in vitro processing system reveal a rapid removal of the poly(A) tails up to termini at the stem-loop structure but little if any influence on further degradation of the RNA. In contrast 3′ poly(A) tracts at RNAs without such stem-loop structures significantly promote total degradation in vitro. To determine the in vivo identity of 3′ nonencoded nucleotides more accurately, pea atp9 transcripts were analyzed by a direct anchor primer ligation-reverse transcriptase PCR approach. This analysis identified maximally 3-nucleotide-long nonencoded extensions most frequently of adenosines combined with cytidines. Processing assays with substrates containing homopolymer stretches of different lengths showed that 10 or more adenosines accelerate RNA processivity, while 3 adenosines have no impact on RNA life span. Thus polyadenylation can generally stimulate the decay of RNAs, but processivity of degradation is almost annihilated by the stabilizing effect of the stem-loop structures. These antagonistic actions thus result in the efficient formation of 3′ processed and stable transcripts. PMID:11154261

Engineering of Pulsatile Conduits from Human Pluripotent Stem Cell Derived Cardiomyocytes

DTIC Science & Technology

2017-06-01

patients with coronary heart disease . Oncotarget [Internet]. 2016 Nov 7; Available from: http://www.ncbi.nlm.nih.gov/pubmed/27835576. 4. Veronesi G...13. SUPPLEMENTARY NOTES 14. ABSTRACT We have derived cardiomyocytes ( heart cells) with high purity using an optimized approach that can coax human...induced pluripotent stem cells (hiPSCs) into heart cells in combination with a two-day lactate selection method that can remove non- cardiomyocytes from

Laser treatments of deep-seated brain lesions

NASA Astrophysics Data System (ADS)

Ward, Helen A.

1997-06-01

The five year survival rate of deep-seated malignant brain tumors after surgery/radiotherapy is virtually 100 percent mortality. Special problems include: (1) Lesions often present late. (2) Position: lesion overlies vital structures, so complete surgical/radiotherapy lesion destruction can damage vital brain-stem functions. (3) Difficulty in differentiating normal brain form malignant lesions. This study aimed to use the unique properties of the laser: (a) to minimize damage during surgical removal of deep-seated brain lesions by operating via fine optic fibers; and (b) to employ the propensity of certain lasers for absorption of dyes and absorption and induction of fluorescence in some brain substances, to differentiate borders of malignant and normal brain, for more complete tumor removal. In the method a fine laser endoscopic technique was devised for removal of brain lesions. The results of this technique, were found to minimize and accurately predict the extent of thermal damage and shock waves to within 1-2mm of the surgical laser beam. Thereby it eliminated the 'popcorn' effect.

An Extended AE-Rich N-Terminal Trunk in Secreted Pineapple Cystatin Enhances Inhibition of Fruit Bromelain and Is Posttranslationally Removed during Ripening1[W][OA

PubMed Central

Neuteboom, Leon W.; Matsumoto, Kristie O.; Christopher, David A.

2009-01-01

Phytocystatins are potent inhibitors of cysteine proteases and have been shown to participate in senescence, seed and organ biogenesis, and plant defense. However, phytocystatins are generally poor inhibitors of the cysteine protease, bromelain, of pineapple (Ananas comosus). Here, we demonstrated that pineapple cystatin, AcCYS1, inhibited (>95%) stem and fruit bromelain. AcCYS1 is a unique cystatin in that it contains an extended N-terminal trunk (NTT) of 63 residues rich in alanine and glutamate. A signal peptide preceding the NTT is processed in vitro by microsomal membranes giving rise to a 27-kD species. AcCYS1 mRNA was present in roots and leaves but was most abundant in fruit. Using immunofluorescence and immunoelectron microscopy with an AcCYS1-specific antiserum, AcCYS1 was found in the apoplasm. Immunoblot analysis identified a 27-kD protein in fruit, roots, and leaves and a 15-kD species in mature ripe fruit. Ripe fruit extracts proteolytically removed the NTT of 27-kD AcCYS1 in vitro to produce the 15-kD species. Mass spectrometry analysis was used to map the primary cleavage site immediately after a conserved critical glycine-94. The AE-rich NTT was required to inhibit fruit and stem bromelain (>95%), whereas its removal decreased inhibition to 20% (fruit) and 80% (stem) and increased the dissociation equilibrium constant by 1.8-fold as determined by surface plasmon resonance assays. We propose that proteolytic removal of the NTT results in the decrease of the inhibitory potency of AcCYS1 against fruit bromelain during fruit ripening to increase tissue proteolysis, softening, and degradation. PMID:19648229

Proximity-Based Differential Single-Cell Analysis of the Niche to Identify Stem/Progenitor Cell Regulators.

PubMed

Silberstein, Lev; Goncalves, Kevin A; Kharchenko, Peter V; Turcotte, Raphael; Kfoury, Youmna; Mercier, Francois; Baryawno, Ninib; Severe, Nicolas; Bachand, Jacqueline; Spencer, Joel A; Papazian, Ani; Lee, Dongjun; Chitteti, Brahmananda Reddy; Srour, Edward F; Hoggatt, Jonathan; Tate, Tiffany; Lo Celso, Cristina; Ono, Noriaki; Nutt, Stephen; Heino, Jyrki; Sipilä, Kalle; Shioda, Toshihiro; Osawa, Masatake; Lin, Charles P; Hu, Guo-Fu; Scadden, David T

2016-10-06

Physiological stem cell function is regulated by secreted factors produced by niche cells. In this study, we describe an unbiased approach based on the differential single-cell gene expression analysis of mesenchymal osteolineage cells close to, and further removed from, hematopoietic stem/progenitor cells (HSPCs) to identify candidate niche factors. Mesenchymal cells displayed distinct molecular profiles based on their relative location. We functionally examined, among the genes that were preferentially expressed in proximal cells, three secreted or cell-surface molecules not previously connected to HSPC biology-the secreted RNase angiogenin, the cytokine IL18, and the adhesion molecule Embigin-and discovered that all of these factors are HSPC quiescence regulators. Therefore, our proximity-based differential single-cell approach reveals molecular heterogeneity within niche cells and can be used to identify novel extrinsic stem/progenitor cell regulators. Similar approaches could also be applied to other stem cell/niche pairs to advance the understanding of microenvironmental regulation of stem cell function. Copyright © 2016 Elsevier Inc. All rights reserved.

Reconsidering the process for bow-stave removal from juniper trees in the Great Basin

Treesearch

Constance I. Millar; Kevin T. Smith

2017-01-01

We question the growth arrestment hypothesis for bow stave removal used by indigenous people in the western Great Basin. Using modern understanding of tree growth and wound response, we suggest that growth would not be arrested by one or two transverse notches along a juniper stem. Rather these would trigger compartmentalization, which limits cambial death to within 10...

Effect of applying an arsenic-resistant and plant growth-promoting rhizobacterium to enhance soil arsenic phytoremediation by Populus deltoides LH05-17.

PubMed

Wang, Q; Xiong, D; Zhao, P; Yu, X; Tu, B; Wang, G

2011-11-01

Bioremediation of highly arsenic (As)-contaminated soil is difficult because As is very toxic for plants and micro-organisms. The aim of this study was to investigate soil arsenic removal effects using poplar in combination with the inoculation of a plant growth-promoting rhizobacterium (PGPR). A rhizobacterium D14 was isolated and identified within Agrobacterium radiobacter. This strain was highly resistant to arsenic and produced indole acetic acid and siderophore. Greenhouse pot bioremediation experiments were performed for 5 months using poplar (Populus deltoides LH05-17) grown on As-amended soils, inoculated with strain D14. The results showed that P. deltoides was an efficient arsenic accumulator; however, high As concentrations (150 and 300 mg kg(-1)) inhibited its growth. With the bacterial inoculation, in the 300 mg kg(-1) As-amended soils, 54% As in the soil was removed, which was higher than the uninoculated treatments (43%), and As concentrations in roots, stems and leaves were significantly increased by 229, 113 and 291%, respectively. In addition, the As translocation ratio [(stems + leaves)/roots = 0·8] was significantly higher than the uninoculated treatments (0·5). About 45% As was translocated from roots to the above-ground tissues. The plant height and dry weight of roots, stems and leaves were all enhanced; the contents of chlorophyll and soluble sugar, and the activities of superoxide dismutase and catalase were all increased; and the content of a toxic compound malondialdehyde was decreased. The results indicated that the inoculation of strain D14 could contribute to the increase in the As tolerance of P. deltoides, promotion of the growth, increase in the uptake efficiency and enhancement of As translocation. The use of P. deltoides in combination with the inoculation of strain D14 provides a potential application for efficient soil arsenic bioremediation. © 2011 The Authors. Journal of Applied Microbiology ©2011 The Society for Applied Microbiology.

Short-Term Metal Ion Trends Following Removal of Recalled Modular Neck Femoral Stems.

PubMed

Barlow, Brian T; Assini, Joseph; Boles, John; Lee, Yuo-Yu; Westrich, Geoffrey H

2015-07-01

Elevated serum metal ions have been well documented with the Rejuvenate modular neck femoral stem (Stryker, Mahwah, NJ); however, the rate at which ion levels decline following revision is less clear. This study included fifty-nine consecutive revisions of Rejuvenate stems for symptomatic ALTR. Blood tests prior to revision and postoperatively at 6weeks, 3months, 6months, and 1year measured serum cobalt and chromium concentrations, ESR, and CRP. At six weeks following revision of a unilateral Rejuvenate, cobalt and chromium levels dropped from preoperative levels by 67% and 42%, respectively. At three months, cobalt levels declined to 19% of preoperative values, but chromium levels remained stable. With this information, surgeons can set realistic expectations for serum metal ion levels following Rejuvenate stem revision. Published by Elsevier Inc.

The persistence of women in STEM: A constructivist grounded theory study

NASA Astrophysics Data System (ADS)

Gamm, Ryan

Men and women have reached relative parity in most sectors of the United States workforce. Yet women remain underrepresented in science, technology, engineering, and mathematics (STEM) fields (AAUW, 2010). Underrepresentation persists despite several decades of research, legislation, and intervention focused on gender equality in STEM fields (Clewell, 2002). The underrepresentation or shortage of women in STEM fields is identifiable primarily in degree attainment, in workforce demographics, and in a gender wage gap. Situated in constructivist grounded theory, this study asks how do women in science, technology, engineering, and mathematics (STEM) fields, particularly those in established career positions, persist when encountering personal and institutional barriers, resistance, and hostility? I use an interpretive-constructivist lens to conduct a grounded theory study exploring the experiences of women who persist in STEM fields, their relation to extant literature on this topic, and the connections to K-12 education practices, specifically curriculum. To understand the connections to curriculum I employ Pinar's (2012) method of currere. Pinar (2012) contends currere "provides a strategy for students of curriculum to study the relations between academic knowledge and life history in the interests of self-understanding and social reconstruction" (p.44). This qualitative study explored nine female STEM workers stories of persistence as each respondent works in STEM fields were gender parity has yet to be established. This study presents a substantive theory: As women persist in STEM fields they reframe themselves to be situated in the overlapping intersection of the social processes that correspond to "engagement" and "persistence." This reframing is possible by interpreting one's present day circumstances by independently removing oneself from current circumstances to understand the cumulative effect of both past and present. The findings highlight the importance of early educative experiences and their reinforcement throughout formal education including the STEM pipeline. The findings suggest that how one understands and interprets STEM work, and the compatibility ones' own identity with this work are crucial, reinforcing the some of the diverse body of literature that seeks to understand women's underrepresentation in STEM. Although literature focused on STEM related education, including work examining gender, offers suggestions compatible with the findings of this study, experiences that are match the stories of the respondents appear to be outside of the norm.

Effects of rhododendron removal on the water use of hardwood species following eastern hemlock mortality

NASA Astrophysics Data System (ADS)

Hawthorne, S. N.; Miniat, C.; Elliott, K.

2017-12-01

Forest disturbance that alters vegetation species composition can affect ecosystem productivity and function. The loss of eastern hemlock (Tsuga canadensis) to hemlock woolly adelgid infestations in southern Appalachian Mountains has resulted in more than a two-fold increase in growth of co-occurring rhododendron (Rhododendron maximum) understory, evergreen shrubs. In contrast, the growth of hardwood species increased by 1.2 fold during the same 5 year period following infestation. This study examines the effects of mechanically removing the rhododendron shrub layer on water use and growth of hardwood species. The treatment—hypothesized to speed ecosystem recovery of structure and function—involved cutting, spreading and burning rhododendron stems to remove both rhododendron and soil O-horizon. Sap flow, soil moisture and micro-climate (humidity, temperature) were measured in a pair of reference and treated plots. Preliminary results from the relatively dry summer/fall 2016 have shown that the mean daily transpiration (Et) of the treated plot was 24% greater than the mean daily Et of hardwood trees in the reference plot (t-test, p < 0.05). Light incident onto the forest floor doubled in the treatment plots compared to the reference plots. This suggests that the removal of the shrub layer reduced competition for resources for the canopy and seedling trees, which may increase tree growth and recruitment. Thus, in the wake of hemlock loss, recovery of riparian forest structure and function may be aided with shrub layer removal.

Deconstructing transcriptional heterogeneity in pluripotent stem cells

PubMed Central

Shalek, Alex K.; Satija, Rahul; DaleyKeyser, AJay; Li, Hu; Zhang, Jin; Pardee, Keith; Gennert, David; Trombetta, John J.; Ferrante, Thomas C.; Regev, Aviv; Daley, George Q.; Collins, James J.

2014-01-01

SUMMARY Pluripotent stem cells (PSCs) are capable of dynamic interconversion between distinct substates, but the regulatory circuits specifying these states and enabling transitions between them are not well understood. We set out to characterize transcriptional heterogeneity in PSCs by single-cell expression profiling under different chemical and genetic perturbations. Signaling factors and developmental regulators show highly variable expression, with expression states for some variable genes heritable through multiple cell divisions. Expression variability and population heterogeneity can be influenced by perturbation of signaling pathways and chromatin regulators. Strikingly, either removal of mature miRNAs or pharmacologic blockage of signaling pathways drives PSCs into a low-noise ground state characterized by a reconfigured pluripotency network, enhanced self-renewal, and a distinct chromatin state, an effect mediated by opposing miRNA families acting on the c-myc / Lin28 / let-7 axis. These data illuminate the nature of transcriptional heterogeneity in PSCs. PMID:25471879

Bone Marrow Adipose Tissue and Skeletal Health.

PubMed

Muruganandan, Shanmugam; Govindarajan, Rajgopal; Sinal, Christopher J

2018-05-31

To summarize and discuss recent progress and novel signaling mechanisms relevant to bone marrow adipocyte formation and its physiological/pathophysiological implications for bone remodeling. Skeletal remodeling is a coordinated process entailing removal of old bone and formation of new bone. Several bone loss disorders such as osteoporosis are commonly associated with increased bone marrow adipose tissue. Experimental and clinical evidence supports that a reduction in osteoblastogenesis from mesenchymal stem cells at the expense of adipogenesis, as well as the deleterious effects of adipocyte-derived signaling, contributes to the etiology of osteoporosis as well as bone loss associated with aging, diabetes mellitus, post-menopause, and chronic drug therapy. However, this view is challenged by findings indicating that, in some contexts, bone marrow adipose tissue may have a beneficial impact on skeletal health. Further research is needed to better define the role of marrow adipocytes in bone physiology/pathophysiology and to determine the therapeutic potential of manipulating mesenchymal stem cell differentiation.

Design modifications of the uncemented Furlong hip stem result in minor early subsidence but do not affect further stability: a randomized controlled RSA study with 5-year follow-up.

PubMed

Weber, Erik; Sundberg, Martin; Flivik, Gunnar

2014-12-01

Even small design modifications of uncemented hip stems may alter the postoperative 3-D migration pattern. The Furlong Active is an uncemented femoral stem which, in terms of design, is based on its precursor-the well-proven Furlong HAC-but has undergone several design changes. The collar has been removed on the Active stem along with the lateral fin; it is shorter and has more rounded edges in the proximal part. We compared the migration patterns of the uncemented Furlong HAC stem and the modified Furlong Active stem in a randomized, controlled trial over 5 years using radiostereometry (RSA). 50 patients with primary osteoarthritis were randomized to receive either the HAC stem or the Active stem. The patients underwent repeated RSA examinations (postoperatively, at 3 months, and after 1, 2, and 5 years) and conventional radiography, and they also filled out hip-specific questionnaires. During the first 3 months, the collarless Active stem subsided to a greater extent than the collar-fitted HAC stem (0.99 mm vs. 0.31 mm, p=0.05). There were, however, no other differences in movement measured by RSA or in clinical outcome between the 2 stems. After 3 months, both stem types had stabilized and almost no further migration was seen. The Active stem showed no signs of unfavorable migration. Our results suggest that the osseointegration is not compromised by the new design features.

Challenges of T Cell Therapies for Virus-associated Diseases after Hematopoietic Stem Cell Transplantation

PubMed Central

Leen, Ann M.; Tripic, Tamara; Rooney, Cliona M.

2009-01-01

Importance of the field Hematopoietic stem cell transplantation (HSCT) is the treatment of choice for many hematological malignancies and genetic disorders. A majority of patients do not have a human leukocyte antigen (HLA) identical sibling donor, and alternative stem cell sources include HLA-matched or mismatched unrelated donors and haploidentical related donors. However, alternative donor HSCT are associated with three major complications (i) graft rejection, (ii) graft-versus-host disease (GvHD) and (iii) delayed immune reconstitution leading to viral infections and relapse. Areas covered in this review Graft rejection and the risk of GvHD can be significantly reduced by using intensive conditioning regimens, including in vivo T cell depletion as well as ex vivo T cell depletion of the graft. However, the benefits of removing alloreactive T cells from the graft are offset by the concomitant removal of T cells with anti-viral or anti-tumor activity as well as the profound delay in endogenous T cell recovery post-transplant. Thus, opportunistic infections, many of which are not amenable to conventional small-molecule therapeutics, are frequent in these patients and are associated with significant morbidity and high mortality rates. This review discusses current cell therapies to prevent or treat viral infections/reactivations post-transplant. What the reader will gain The reader will gain an understanding of the current state of cell therapy to prevent and treat viral infections post-HSCT, and will be introduced to preclinical studies designed to develop and validate new manufacturing procedures intended to improve therapeutic efficacy and reduce associated toxicities. Take home message Reconstitution of HSCT recipients with antigen-specific T cells, produced either by allodepletion or in vitro reactivation, can offer an effective strategy to provide both immediate and long-term protection without harmful alloreactivity. PMID:20132056

Natural biosorbents (garlic stem and horse chesnut shell) for removal of chromium(VI) from aqueous solutions.

PubMed

Parlayıcı, Şerife; Pehlivan, Erol

2015-12-01

The biosorption of Cr(VI) by the garlic stem (GS)-Allium sativum L. and horse chesnut shell (HCS)-Aesculus hippocastanum plant residues in a batch type reactor was studied in detail for the purpose of wastewater treatment. The influence of initial Cr(VI) concentration, time, and pH was investigated to optimize Cr(VI) removal from aqueous solutions and equilibrium isotherms and kinetic data. This influence was evaluated. The adsorption capacity of the GS and the HCS for Cr(VI) was determined with the Langmuir and Freundlich isotherm models, and the data was fitted to the Langmuir. The adsorption capacity of the GS and the HCS was found to be 103.09 and 142.85 mg/g of adsorbent from a solution containing 3000 ppm of Cr(VI), respectively. The GS's capacity was considerably lower than that of the HCS in its natural form. Gibbs free energy was spontaneous for all interactions, and the adsorption process exhibited exothermic enthalpy values. The HCS was shown to be a promising biosorbent for Cr(VI) removal from aqueous solutions.

Electric field effects on ion currents in satellite wakes

NASA Technical Reports Server (NTRS)

Parks, D. E.; Katz, I.

1985-01-01

Small currents associated with satellite spin, dielectric conduction, or trace concentrations of H+, can have a substantial effect on the potential of a satellite and the particle currents reaching its surface. The importance of such small currents at altitudes below about 300 km stems from the extremely small 0+ currents impinging on the wake-side of the spacecraft. The particle current on the downstream side of the AE-C satellite is considered. Theoretical estimates based on a newly described constant of the motion of a particle indicate that accounting for small concentrations of H+ remove a major discrepancy between calculated and measured currents.

Effects of properties of manganese oxide-impregnated catalysts and flue gas condition on multipollutant control of Hg0 and NO.

PubMed

Chiu, Chun-Hsiang; Hsi, Hsing-Cheng; Lin, Hong-Ping; Chang, Tien-Chin

2015-06-30

This research investigated the effects of manganese oxide (MnOx) impregnation on the physical/chemical properties and multi pollutant control effectiveness of Hg(0) and NO using a V2O5-WO3/TiO2-SiO2 selective catalytic reduction (SCR) catalyst. Raw and MnOx-treated SCR samples were bean-shaped nanoparticles with sizes within 10-30 nm. Impregnating MnOx of ≤ 5 wt% caused limited changes in physical properties of the catalyst. The decrease in surface area when the impregnated MnOx amount was 10 wt% may stem from the pore blockage and particle growth or aggregation of the catalyst. Mn(4+) was the main valence state of impregnated MnOx. Apparent crystallinity of MnOx was not observed based on X-ray diffraction. MnOx impregnation enhanced the Hg(0) oxidation and NO/SO2 removal of SCR catalyst. The 5 and 10% MnOx-impregnated samples had the greatest multi pollutant control potentials for Hg(0) oxidation and NO removal; however, the increasing SO2 removal that may be mainly due to SO2-SO3 conversion should be cautioned. HCl and O2 greatly promoted Hg(0) oxidation. SO2 enhanced Hg(0) oxidation at ≤ 200 ppm while NO and NH3 consistently inhibited Hg(0) oxidation. Elevating flue gas temperature enhanced Hg(0) oxidation. Overall, MnOx-impregnated catalysts show stable and consistent multi pollutant removal effectiveness under the test conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of cemented versus press-fit primary humeral stem fixation in the setting of revision shoulder arthroplasty.

PubMed

Salesky, Madeleine A; Grace, Trevor R; Feeley, Brian T; Ma, C Benjamin; Zhang, Alan L

2018-05-01

The influence of primary humeral stem fixation method (cemented or press fit) on intraoperative or postoperative outcomes in the setting of revision shoulder arthroplasty is unknown. A retrospective analysis of a prospectively collected cohort of revision shoulder arthroplasty patients from a single tertiary center was performed. Demographic variables, intraoperative data, and 90-day complication rates were compared between cemented and press-fit primary stem fixation cohorts. Follow-up radiographs were graded and compared using a modified Gruen system for humeral lucencies. Eighty-six primary shoulder replacements (34 hemiarthroplasties, 39 anatomic total shoulder arthroplasties, 13 reverse total shoulder arthroplasties) underwent revision arthroplasty with humeral stem removal between 2004 and 2017. Forty-five patients had cemented primary humeral fixation and 41 had press-fit fixation. The cemented cohort was older than the cementless cohort (66.6 vs. 61.4 years; P = .03) but otherwise demonstrated no difference in gender, body mass index, type of primary prosthesis (hemi, total, or reverse), or time between primary and revision operations. The cemented and cementless cohorts showed similar rates of humeral osteotomy (28.9% vs. 29.3%; P = .97), operative time (133.5  vs. 121.3 minutes; P = .16), and 90-day complication rates (13.3% vs. 9.8%; P = .61). Cemented vs. press-fit primary stems also had similar rates of humeral lucencies seen on follow-up radiographs after revision (77.1% vs. 60.6%; P = .14). Humeral stem fixation with or without cement during primary shoulder arthroplasty demonstrated similar operative time, need for intraoperative humeral osteotomy, and postoperative complication rates in the setting of revision arthroplasty. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

α6β1- and αV-integrins are required for long-term self-renewal of murine embryonic stem cells in the absence of LIF.

PubMed

Cattavarayane, Sandhanakrishnan; Palovuori, Riitta; Tanjore Ramanathan, Jayendrakishore; Manninen, Aki

2015-02-27

The growth properties and self-renewal capacity of embryonic stem (ES) cells are regulated by their immediate microenvironment such as the extracellular matrix (ECM). Integrins, a central family of cellular ECM receptors, have been implicated in these processes but their specific role in ES cell self-renewal remains unclear. Here we have studied the effects of different ECM substrates and integrins in mouse ES cells in the absence of Leukemia Inhibitory Factor (LIF) using short-term assays as well as long-term cultures. Removal of LIF from ES cell culture medium induced morphological differentiation of ES cells into polarized epistem cell-like cells. These cells maintained epithelial morphology and expression of key stemness markers for at least 10 passages in the absence of LIF when cultured on laminin, fibronectin or collagen IV substrates. The specific functional roles of α6-, αV- and β1-integrin subunits were dissected using stable lentivirus-mediated RNAi methodology. β1-integrins were required for ES cell survival in long-term cultures and for the maintenance of stem cell marker expression. Inhibition of α6-integrin expression compromised self-renewal on collagen while αV-integrins were required for robust ES cell adhesion on laminin. Analysis of the stemness marker expression revealed subtle differences between α6- and αV-depleted ES cells but the expression of both was required for optimal self-renewal in long-term ES cell cultures. In the absence of LIF, long-term ES cell cultures adapt an epistem cell-like epithelial phenotype and retain the expression of multiple stem cell markers. Long-term maintenance of such self-renewing cultures depends on the expression of β1-, α6- and αV-integrins.

Engineering of a Potent Recombinant Lectin-Toxin Fusion Protein to Eliminate Human Pluripotent Stem Cells.

PubMed

Tateno, Hiroaki; Saito, Sayoko

2017-07-10

The use of human pluripotent stem cells (hPSCs) such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) in regenerative medicine is hindered by their tumorigenic potential. Previously, we developed a recombinant lectin-toxin fusion protein of the hPSC-specific lectin rBC2LCN, which has a 23 kDa catalytic domain (domain III) of Pseudomonas aeruginosa exotoxin A (rBC2LCN-PE23). This fusion protein could selectively eliminate hPSCs following its addition to the cell culture medium. Here we conjugated rBC2LCN lectin with a 38 kDa domain of exotoxin A containing domains Ib and II in addition to domain III (PE38). The developed rBC2LCN-PE38 fusion protein could eliminate 50% of 201B7 hPSCs at a concentration of 0.003 μg/mL (24 h incubation), representing an approximately 556-fold higher activity than rBC2LCN-PE23. Little or no effect on human fibroblasts, human mesenchymal stem cells, and hiPSC-derived hepatocytes was observed at concentrations lower than 1 μg/mL. Finally, we demonstrate that rBC2LCN-PE38 selectively eliminates hiPSCs from a mixed culture of hiPSCs and hiPSC-derived hepatocytes. Since rBC2LCN-PE38 can be prepared from soluble fractions of E. coli culture at a yield of 9 mg/L, rBC2LCN-PE38 represents a practical reagent to remove human pluripotent stem cells residing in cultured cells destined for transplantation.

[Embryonic stem cells and therapeutic cloning].

PubMed

Sunde, A; Eftedal, I

2001-08-30

Increased interest in the therapeutic use of human stem cells has emerged following significant progress in ongoing research. The cloning of a sheep, the isolation of human embryonic stem cells, and the discovery that adult stem cells may be reprogrammed taken together give substance to hopes that novel principles of treatment may be developed for a variety of serious conditions. Embryonic stem cells are derived from pre-embryos at the blastocyst stage and may give rise to all bodily tissues and cells. Animal models have demonstrated that embryonic stem cells when transplanted into adult hosts may differentiate and develop into cells and tissues applicable for treatment of a variety of conditions, including Parkinson's disease, multiple sclerosis, spinal injuries, cardiac stroke and cancer. Transplanted embryonic stem cells are exposed to immune reactions similar to those acting on organ transplants, hence immunosuppression of the recipient is generally required. It is, however, possible to obtain embryonic stem cells that are genetically identical to the patient's own cells by means of therapeutic cloning techniques. The nucleus from a somatic cell is transferred into an egg after removal of the egg's own genetic material. Under specific condition the egg will use genetic information from the somatic cell in organising the formation of a blastocyst which in turn generates embryonic stem cells. These cells have a genetic composition identical to that of the patient and are suitable for stem cell therapy.

Evidence of progenitor cells in the adult human cochlea: sphere formation and identification of ABCG2.

PubMed

Massucci-Bissoli, Milene; Lezirovitz, Karina; Oiticica, Jeanne; Bento, Ricardo Ferreira

2017-11-01

The aim of this study was to search for evidence of stem or progenitor cells in the adult human cochlea by testing for sphere formation capacity and the presence of the stem cell marker ABCG2. Cochleas removed from patients undergoing vestibular schwannoma resection (n=2) and from brain-dead organ donors (n=4) were dissociated for either flow cytometry analysis for the stem cell marker ABCG2 or a sphere formation assay that is widely used to test the sphere-forming capacity of cells from mouse inner ear tissue. Spheres were identified after 2-5 days in vitro, and the stem cell marker ABCG2 was detected using flow cytometric analysis after cochlear dissociation. Evidence suggests that there may be progenitor cells in the adult human cochlea, although further studies are required.

The Removal of Human Breast Cancer Cells from Hematopoietic CD34+ Stem Cells by Dielectrophoretic Field-Flow-Fractionation

PubMed Central

HUANG, YING; YANG, JUN; WANG, XIAO-BO; BECKER, FREDERICK F.; GASCOYNE, PETER R.C.

2009-01-01

Dielectrophoretic field-flow-fractionation (DEP-FFF) was used to purge human breast cancer MDA-435 cells from hematopoietic CD34+ stem cells. An array of interdigitated microelectrodes lining the bottom surface of a thin chamber was used to generate dielectrophoretic forces that levitated the cell mixture in a fluid flow profile. CD34+ stem cells were levitated higher, were carried faster by the fluid flow, and exited the separation chamber earlier than the cancer cells. Using on-line flow cytometry, efficient separation of the cell mixture was observed in less than 12 min, and CD34+ stem cell fractions with a purity >99.2% were obtained. The method of DEP-FFF is potentially applicable to many biomedical cell separation problems, including microfluidic-scale diagnosis and preparative-scale purification of cell subpopulations. PMID:10791899

Removal of transmissible spongiform encephalopathy prion from large volumes of cell culture media supplemented with fetal bovine serum by using hollow fiber anion-exchange membrane chromatography.

PubMed

Chou, Ming Li; Bailey, Andy; Avory, Tiffany; Tanimoto, Junji; Burnouf, Thierry

2015-01-01

Cases of variant Creutzfeldt-Jakob disease in people who had consumed contaminated meat products from cattle with bovine spongiform encephalopathy emphasize the need for measures aimed at preventing the transmission of the pathogenic prion protein (PrPSc) from materials derived from cattle. Highly stringent scrutiny is required for fetal bovine serum (FBS), a growth-medium supplement used in the production of parenteral vaccines and therapeutic recombinant proteins and in the ex vivo expansion of stem cells for transplantation. One such approach is the implementation of manufacturing steps dedicated to removing PrPSc from materials containing FBS. We evaluated the use of the QyuSpeed D (QSD) adsorbent hollow-fiber anion-exchange chromatographic column (Asahi Kasei Medical, Tokyo, Japan) for the removal of PrPSc from cell culture media supplemented with FBS. We first established that QSD filtration had no adverse effect on the chemical composition of various types of culture media supplemented with 10% FBS or the growth and viability characteristics of human embryonic kidney (HEK293) cells, baby hamster kidney (BHK-21) cells, African green monkey kidney (Vero) cells, and Chinese hamster ovary (CHO-k1) cells propagated in the various culture-medium filtrates. We used a 0.6-mL QSD column for removing PrPSc from up to 1000 mL of Dulbecco's modified Eagle's medium containing 10% FBS previously spiked with the 263K strain of hamster-adapted scrapie. The Western blot analysis, validated alongside an infectivity assay, revealed that the level of PrPSc in the initial 200mL flow-through was reduced by 2.5 to > 3 log10, compared with that of the starting material. These results indicate that QSD filtration removes PrPSc from cell culture media containing 10% FBS, and demonstrate the ease with which QSD filtration can be implemented in at industrial-scale to improve the safety of vaccines, therapeutic recombinant proteins, and ex vivo expanded stem cells produced using growth media supplemented with FBS.

Removal of Transmissible Spongiform Encephalopathy Prion from Large Volumes of Cell Culture Media Supplemented with Fetal Bovine Serum by Using Hollow Fiber Anion-Exchange Membrane Chromatography

PubMed Central

Chou, Ming Li; Bailey, Andy; Avory, Tiffany; Tanimoto, Junji; Burnouf, Thierry

2015-01-01

Cases of variant Creutzfeldt-Jakob disease in people who had consumed contaminated meat products from cattle with bovine spongiform encephalopathy emphasize the need for measures aimed at preventing the transmission of the pathogenic prion protein (PrPSc) from materials derived from cattle. Highly stringent scrutiny is required for fetal bovine serum (FBS), a growth-medium supplement used in the production of parenteral vaccines and therapeutic recombinant proteins and in the ex vivo expansion of stem cells for transplantation. One such approach is the implementation of manufacturing steps dedicated to removing PrPSc from materials containing FBS. We evaluated the use of the QyuSpeed D (QSD) adsorbent hollow-fiber anion-exchange chromatographic column (Asahi Kasei Medical, Tokyo, Japan) for the removal of PrPSc from cell culture media supplemented with FBS. We first established that QSD filtration had no adverse effect on the chemical composition of various types of culture media supplemented with 10% FBS or the growth and viability characteristics of human embryonic kidney (HEK293) cells, baby hamster kidney (BHK-21) cells, African green monkey kidney (Vero) cells, and Chinese hamster ovary (CHO-k1) cells propagated in the various culture-medium filtrates. We used a 0.6-mL QSD column for removing PrPSc from up to 1000 mL of Dulbecco’s modified Eagle’s medium containing 10% FBS previously spiked with the 263K strain of hamster-adapted scrapie. The Western blot analysis, validated alongside an infectivity assay, revealed that the level of PrPSc in the initial 200mL flow-through was reduced by 2.5 to > 3 log10, compared with that of the starting material. These results indicate that QSD filtration removes PrPSc from cell culture media containing 10% FBS, and demonstrate the ease with which QSD filtration can be implemented in at industrial-scale to improve the safety of vaccines, therapeutic recombinant proteins, and ex vivo expanded stem cells produced using growth media supplemented with FBS. PMID:25874629

Hip arthroplasty today and tomorrow.

PubMed

Amstutz, H C

1987-12-01

Acrylic-fixed total hip and surface replacement arthroplasty have been very effective in affording immediate relief of pain and providing improved function. Complications have been reduced by improvements in design, materials, and especially technique. They are now very low in the elderly, and the stem type acrylic-fixed design remains the procedure of choice. The failure rates in youthful patients and those with bone-stock deficiencies have been high in both THR and surface types, although the latter had the advantage of preserving femoral stock. On the femoral side, the new "macro" femoral designs from Europe and "micro" femoral porous designs have shown promise, but thigh pain, incomplete and difficult to predict bone ingrowth patterns, coupled with removal problems have influenced design and technique changes. Both press-fit stem types and porous surface replacements have produced promising initial results with less potential downside risks. On the acetabular side, both the cementless hemispherical with screw-type adjuvant fixation, or the chamfered cylinder designs, used primarily with the UCLA porous surface replacements, but also with stem-type devices, appear to achieve best short-term results, while the entire variety of screw rings are disappointing. The future will bring further refinements in technique and specific indications for certain types of replacement stem in specific types of bone stock deficiencies. The all ceramic-ceramic and ceramic-polyethylene bearings show promise of reducing wear and, hence, should improve longevity of implant fixation.

Roles of autophagy in controlling stem cell identity: a perspective of self-renewal and differentiation.

PubMed

Sotthibundhu, Areechun; Promjuntuek, Wilasinee; Liu, Min; Shen, Sanbing; Noisa, Parinya

2018-04-25

Autophagy is crucial for the removal of dysfunctional organelles and protein aggregates and for maintaining stem cell homeostasis, which includes self-renewal, cell differentiation and somatic reprogramming. Loss of self-renewal capacity and pluripotency is a major obstacle to stem cell-based therapies. It has been reported that autophagy regulates stem cells under biological stimuli, starvation, hypoxia, generation of reactive oxygen species (ROS) and cellular senescence. On the one hand, autophagy is shown to play roles in self-renewal by co-function with the ubiquitin-proteasome system (UPS) to promote pluripotency-associated proteins (NANOG, OCT4 and SOX2) in human embryonic stem cells (hESCs). On the other hand, autophagy activity acts as cell reprogramming processes that play an important role for clearance fate determination and upregulates neural and cardiac differentiation. Deregulation of autophagy triggers protein disorders such as neurodegenerative cardiac/muscle diseases and cancer. Therefore, understanding of the roles of the autophagy in stem cell renewal and differentiation may benefit therapeutic development for a range of human diseases.

Positive and negative effects of grass, cattle, and wild herbivores on Acacia saplings in an East African savanna.

PubMed

Riginos, Corinna; Young, Truman P

2007-10-01

Plant-plant interactions can be a complex mixture of positive and negative interactions, with the net outcome depending on abiotic and community contexts. In savanna systems, the effects of large herbivores on tree-grass interactions have rarely been studied experimentally, though these herbivores are major players in these systems. In African savannas, trees often become more abundant under heavy cattle grazing but less abundant in wildlife preserves. Woody encroachment where cattle have replaced wild herbivores may be caused by a shift in the competitive balance between trees and grasses. Here we report the results of an experiment designed to quantify the positive, negative, and net effects of grasses, wild herbivores, and cattle on Acacia saplings in a Kenyan savanna. Acacia drepanolobium saplings under four long-term herbivore regimes (wild herbivores, cattle, cattle + wild herbivores, and no large herbivores) were cleared of surrounding grass or left with the surrounding grass intact. After two years, grass-removal saplings exhibited 86% more browse damage than control saplings, suggesting that grass benefited saplings by protecting them from herbivory. However, the negative effect of grass on saplings was far greater; grass-removal trees accrued more than twice the total stem length of control trees. Where wild herbivores were present, saplings were browsed more and produced more new stem growth. Thus, the net effect of wild herbivores was positive, possibly due to the indirect effects of lower competitor tree density in areas accessible to elephants. Additionally, colonization of saplings by symbiotic ants tracked growth patterns, and colonized saplings experienced lower rates of browse damage. These results suggest that savanna tree growth and woody encroachment cannot be predicted by grass cover or herbivore type alone. Rather, tree growth appears to depend on a variety of factors that may be acting together or antagonistically at different stages of the tree's life cycle.

Aggregation in the tick Ixodes ricinus (Acari: Ixodidae): use and reuse of questing vantage points.

PubMed

Healy, John A E; Bourke, Patrick

2008-03-01

Ongoing work in oak woods in Killarney National Park in southwestern Ireland is focusing on the factors influencing the fine-scale aggregated distribution of Ixodes ricinus L. (Acari: Ixodidae) on the ground. The extent of reuse of stems of vegetation as questing points by adult ticks was determined by paint-marking stems on which ticks were found, counting and removing these ticks, and subsequently reexamining the same stems for ticks on two further occasions. Overall, an estimated 2,967 stems in 123 separate rush plants (Juncus effusus L.) were examined. Statistical analysis of the data demonstrated a highly significant reoccupancy by ticks of stems previously and recently used. Furthermore, it is shown that the extent of stem reuse by ticks is significantly and positively correlated with the numbers of ticks originally observed on those stems. Although other factors may be involved in generating clumping of ticks, the results are compatible with the proposition that aggregation of I. ricinus on the ground is pheromone-mediated. The findings are discussed in relation to what is known about the powers of lateral movement of I. ricinus on the ground and the possible implications for the performance of tick traps.

Phytoextraction of rare earth elements in herbaceous plant species growing close to roads.

PubMed

Mikołajczak, Patrycja; Borowiak, Klaudia; Niedzielski, Przemysław

2017-06-01

The aim of study was to determine the phytoextraction of rare earth elements (REEs) to roots, stems and leaves of five herbaceous plant species (Achillea millefolium L., Artemisia vulgaris L., Papaver rhoeas L., Taraxacum officinale AND Tripleurospermum inodorum), growing in four areas located in close proximity to a road with varied traffic intensity. Additionally, the relationship between road traffic intensity, REE concentration in soil and the content of these elements in plant organs was estimated. A. vulgaris and P. rhoeas were able to effectively transport REEs in their leaves, independently of area collection. The highest content of REEs was observed in P. rhoeas leaves and T. inodorum roots. Generally, HREEs were accumulated in P. rhoeas roots and leaves and also in the stems of T. inodorum and T. officinale, whereas LREEs were accumulated in T. inodorum roots and T. officinale stems. It is worth underlining that there was a clear relationship between road traffic intensity and REE, HREE and LREE concentration in soil. No positive correlation was found between the concentration of these elements in soil and their content in plants, with the exception of T. officinale. An effective transport of REEs from the root system to leaves was observed, what points to the possible ability of some of the tested plant species to remove REEs from soils near roads.

Hepatoprotective effect of the aqueous extract of Simarouba amara Aublet (Simaroubaceae) stem bark against carbon tetrachloride (CCl4)-induced hepatic damage in rats.

PubMed

Maranhão, Hélida M L; Vasconcelos, Carlos F B; Rolim, Larissa A; Neto, Pedro J Rolim; Neto, Jacinto da C Silva; Filho, Reginaldo C da Silva; Fernandes, Mariana P; Costa-Silva, João H; Araújo, Alice V; Wanderley, Almir G

2014-10-31

Simarouba amara stem bark decoction has been traditionally used in Brazil to treat malaria, inflammation, fever, abdominal pain, diarrhea, wounds and as a tonic. In this study, we investigate the hepatoprotective effects of the aqueous extract of S. amara stem bark (SAAE) on CCl4-induced hepatic damage in rats. SAAE was evaluated by high performance liquid chromatography. The animals were divided into six groups (n = 6/group). Groups I (vehicle-corn oil), II (control-CCl4), III, IV, V and VI were pretreated during 10 consecutive days, once a day p.o, with Legalon® 50 mg/kg b.w, SAAE at doses 100, 250 and 500 mg/kg b.w, respectively. The hepatotoxicity was induced on 11th day with 2 mL/kg of 20% CCl4 solution. 24 h after injury, the blood samples were collected and their livers were removed to biochemical and immunohistochemical analyzes. The SAAE decreased the levels of liver markers and lipid peroxidation in all doses and increased the catalase levels at doses 250 and 500 mg/kg. Immunohistochemical results suggested hepatocyte proliferation in all doses. These results may be related to catechins present in SAAE. Thus, SAAE prevented the oxidative damage at the same time that increased regenerative and reparative capacities of the liver.

Adhesion modification of neural stem cells induced by nanoscale ripple patterns

NASA Astrophysics Data System (ADS)

Pedraz, P.; Casado, S.; Rodriguez, V.; Giordano, M. C.; Buatier de Mongeot, F.; Ayuso-Sacido, A.; Gnecco, E.

2016-03-01

We have studied the influence of anisotropic nanopatterns (ripples) on the adhesion and morphology of mouse neural stem cells (C17.2) on glass substrates using cell viability assay, optical microscopy and atomic force microscopy. The ripples were produced by defocused ion beam sputtering with inert Ar ions, which physically remove atoms from the surface at the energy of 800 eV. The ripple periodicity (∼200 nm) is comparable to the thickness of the cytoplasmatic microspikes (filopodia) which link the stem cells to the substrate. All methods show that the cell adhesion is significantly lowered compared to the same type of cells on flat glass surfaces. Furthermore, the AFM analysis reveals that the filopodia tend to be trapped parallel or perpendicular to the ripples, which limits the spreading of the stem cell on the rippled substrate. This opens the perspective of controlling the micro-adhesion of stem cells and the orientation of their filopodia by tuning the anisotropic substrate morphology without chemical reactions occurring at the surface.

Improving Underrepresented Minority Student Persistence in STEM

PubMed Central

Estrada, Mica; Burnett, Myra; Campbell, Andrew G.; Campbell, Patricia B.; Denetclaw, Wilfred F.; Gutiérrez, Carlos G.; Hurtado, Sylvia; John, Gilbert H.; Matsui, John; McGee, Richard; Okpodu, Camellia Moses; Robinson, T. Joan; Summers, Michael F.; Werner-Washburne, Maggie; Zavala, MariaElena

2016-01-01

Members of the Joint Working Group on Improving Underrepresented Minorities (URMs) Persistence in Science, Technology, Engineering, and Mathematics (STEM)—convened by the National Institute of General Medical Sciences and the Howard Hughes Medical Institute—review current data and propose deliberation about why the academic “pathways” leak more for URM than white or Asian STEM students. They suggest expanding to include a stronger focus on the institutional barriers that need to be removed and the types of interventions that “lift” students’ interests, commitment, and ability to persist in STEM fields. Using Kurt Lewin’s planned approach to change, the committee describes five recommendations to increase URM persistence in STEM at the undergraduate level. These recommendations capitalize on known successes, recognize the need for accountability, and are framed to facilitate greater progress in the future. The impact of these recommendations rests upon enacting the first recommendation: to track successes and failures at the institutional level and collect data that help explain the existing trends. PMID:27543633

Effective removal of phosphate from aqueous solution using humic acid coated magnetite nanoparticles.

PubMed

Rashid, Mamun; Price, Nathaniel T; Gracia Pinilla, Miguel Ángel; O'Shea, Kevin E

2017-10-15

Effective removal of excess phosphate from water is critical to counteract eutrophication and restore water quality. In this study, low cost, environmentally friendly humic acid coated magnetite nanoparticles (HA-MNP) were synthesized and applied for the remediation of phosphate from aqueous media. The HA-MNPs, characterized by FTIR, TEM and HAADF-STEM showed the extensive coating of humic acid on the magnetite surface. The magnetic nanoparticles with diameters of 7-12 nm could be easily separated from the reaction mixture by using a simple hand held magnet. Adsorption studies demonstrate the fast and effective separation of phosphate with maximum adsorption capacity of 28.9 mg/g at pH 6.6. The adsorption behavior follows the Freundlich isotherm suggesting the formation of non-uniform multilayers of phosphate on the heterogeneous surface of HA-MNP. The adsorption kinetic fits the pseudo-second order model well with rate constants of 0.206 ± 0.003, 0.073 ± 0.002 and 0.061 ± 0.003 g mg -1 min -1 for phosphate (P) concentrations of 2, 5 and 10 mg/L respectively. The removal of phosphate was found higher at acidic and neutral pH compared to basic conditions. The nanoparticles exhibit good selectivity and adsorption efficiency for phosphate in presence of co-existing ions such as Cl - , SO 4 2- and NO 3 - with some inhibition effect by CO 3 2- . The effect of temperature on the adsorption reveals that the process is endothermic and spontaneous. HA-MNPs are promising, simple, environmentally friendly materials for the removal of phosphate from aqueous media. Copyright © 2017. Published by Elsevier Ltd.

Seasonal dynamics of radial growth and stem water deficit in co-occurring saplings and mature conifers under drought: Canopy density affects water stress experienced by saplings

NASA Astrophysics Data System (ADS)

Oberhuber, Walter

2017-04-01

Size-mediated climate sensitivity of trees will affect forest structure, composition and productivity under a warmer and drier climate. Therefore, the influence of tree size (saplings vs. mature trees) and site conditions on radial stem growth and stem water deficit of Picea abies (dry-mesic site; canopy cover [CC]: 70 %) and Pinus sylvestris (xeric site; CC: 30 %) were evaluated in a drought-prone inner Alpine environment (c. 750 m a.s.l.). Stem radius variations (SRVs) of saplings (mean stem diameter [SDM]: 2.3 cm) and co-occurring mature trees (SDM: 24 cm) were continuously recorded by dendrometers during two years (n = 6 - 8 individuals per species and size class). Growth-detrended SRVs (SSRV), which represent reversible shrinkage and swelling of tissues outside the cambium and contribute most to stem water storage capacity, were calculated by removing the Gompertz-modeled daily growth from SRVs. Dendrometer records revealed that irrespective of tree size, radial growth in Pinus sylvestris occurred in April-May, whereas the main growing period of Picea abies was April-June and May-June in saplings and mature trees, respectively. Growth-detrended SRVs were approximately twice as large in Pinus sylvestris compared to Picea abies indicating more intense exploitation of stem water reserves at the xeric site. Linear relationships between SSRVs of mature trees vs. saplings and climate-SSRV relationships revealed greater use of stem water reserves by mature Picea abies compared to saplings. This suggests that the strikingly depressed radial growth of Picea abies saplings was primarily caused by reduced carbon availability beneath the dense canopy. In contrast, a tree size effect on the seasonal dynamics of radial growth, stem water deficit and climate-SSRV relationships was mostly lacking in Pinus sylvestris, indicating comparable water status in mature trees and saplings under an open canopy. Results of this study provide evidence that development of a buffered microclimate under dense canopy mitigates water stress experienced by saplings and favors tree recruitment at drought-prone sites. This study was funded by the Austrian Science Fund (FWF): P25643-B16 "Carbon allocation and growth of Scots pine".

[Early aseptic loosening of the CF 30 femoral stem].

PubMed

Kovanda, M; Havlícek, V; Hudec, J

2007-02-01

The CF 30 stem in combination with a cementless acetabulum was used at the First Department of Orthopedic Surgery in Brno in the years 1994 to 1995. From the second year following implantation, aseptic stem loosening was recorded. In order to find explanation of this early loosening, the authors, in cooperation with the Institute of Solid Mechanics, Mechatronics and Biomechanics, carried out the stress-strain analysis in a model system. Eighty patients (31 men and 49 women) received a cemented CF30 femoral component in 1994. Of them, 16 patients underwent revision arthroplasty, three died of causes unrelated to the surgery, and four were lost to follow-up. The final clinical and radiographic check-up was carried out in 2001. The results of a comprehensive examination were available in 57 patients with a CF30 stem. The patients were evaluated on the basis of the Harris hip score and anteroposterior radiographs of the hip. X-ray films obtained immediately after surgery and those taken at regular intervals during follow-up were compared. The following characteristics were noted: translucent lines in individual zones along the stem at the cement-bone interface; osteolysis, i. e., non-linear translucent areas, at least 5 mm long, at the cement-bone interface; and subsidence of the femoral component, i. e., migration of the stem distal to the tip of the greater trochanter. The CF 30 stem survival curve showed that aseptic stem loosening occurred from post-implantation year 2, and increased during the following years. At 6 years and 6 months, a total of 16 patients underwent revision surgery, involving reimplantation in 14 and implant removal in 2 patients. Potential causes of aseptic loosening: Polyethylene wear.However, no acetabular loosening was found in this group, although acetabular components are reported to become loose more often than femoral components. By comparison of the stem survival curves for Poldi and CF 30 stems it appeared that, at 6 years and 6 months, the Poldi stem survival curve showed better results. Matt surface finish of the stem. However, the link between the CF 30 stem and cement was so strong that, in all 16 revised hips, the stem was removed together with nearly a complete cement mantle. The authors therefore dismiss this as a cause. Also, in the remaining cases of CF 30 aseptic loosening, which had not been revised, radiographic evidence suggested loosening between bone and cement. The authors did not find any movement of the CF stem in its cement mantle. The stem always fitted in with the cement mantle. Erroneous surgical technique or cementing was unlikely. The procedures were performed by experienced orthopedic surgeons who used the second-generation cementing technique. In patients with a Poldi stem, the first-generation cementing method was used and the proportion of aseptic loosening at 6 years of follow-up was only 4 %. In contrast, loosening in patients with the CF 30 stem was 20 % at 6 years and 6 months postoperatively. Shape of the CF 30 stem with the intention to find a relationship between stem shape and its early aseptic loosening, the authors started cooperation with the Institute of Solid Mechanics, Mechatronics and Biomechanics at the Faculty of Mechanical Engineering, Brno University of Technology. Using the method of finite elements, they carried out the stressstrain analysis in a model system. Stress at the cement-bone interface in the CF 30 stem was higher than in the Poldi stem, and this difference was statistically significant. The authors believe that the more frequent loosening found in patients with the CF 30 stem can be accounted for by its shape. The survival curve for the CF 30 femoral stem did not show good results, and therefore this stem is not recommended for implantation. The authors suggest that a more frequent early aseptic loosening of CF 30 stems may have been caused by its unsuitable shape.

A photoreversible protein-patterning approach for guiding stem cell fate in three-dimensional gels

NASA Astrophysics Data System (ADS)

Deforest, Cole A.; Tirrell, David A.

2015-05-01

Although biochemically patterned hydrogels are capable of recapitulating many critical aspects of the heterogeneous cellular niche, exercising spatial and temporal control of the presentation and removal of biomolecular signalling cues in such systems has proved difficult. Here, we demonstrate a synthetic strategy that exploits two bioorthogonal photochemistries to achieve reversible immobilization of bioactive full-length proteins with good spatial and temporal control within synthetic, cell-laden biomimetic scaffolds. A photodeprotection-oxime-ligation sequence permits user-defined quantities of proteins to be anchored within distinct subvolumes of a three-dimensional matrix, and an ortho-nitrobenzyl ester photoscission reaction facilitates subsequent protein removal. By using this approach to pattern the presentation of the extracellular matrix protein vitronectin, we accomplished reversible differentiation of human mesenchymal stem cells to osteoblasts in a spatially defined manner. Our protein-patterning approach should provide further avenues to probe and direct changes in cell physiology in response to dynamic biochemical signalling.

A Simple and Robust Method for Culturing Human-Induced Pluripotent Stem Cells in an Undifferentiated State Using Botulinum Hemagglutinin.

PubMed

Kim, Mee-Hae; Matsubara, Yoshifumi; Fujinaga, Yukako; Kino-Oka, Masahiro

2018-02-01

Clinical and industrial applications of human-induced pluripotent stem cells (hiPSCs) is hindered by the lack of robust culture strategies capable of sustaining a culture in an undifferentiated state. Here, a simple and robust hiPSC-culture-propagation strategy incorporating botulinum hemagglutinin (HA)-mediated selective removal of cells deviating from an undifferentiated state is developed. After HA treatment, cell-cell adhesion is disrupted, and deviated cells detached from the central region of the colony to subsequently form tight monolayer colonies following prolonged incubation. The authors find that the temporal and dose-dependent activity of HA regulated deviated-cell removal and recoverability after disruption of cell-cell adhesion in hiPSC colonies. The effects of HA are confirmed under all culture conditions examined, regardless of hiPSC line and feeder-dependent or -free culture conditions. After routine application of our HA-treatment paradigm for serial passages, hiPSCs maintains expression of pluripotent markers and readily forms embryoid bodies expressing markers for all three germ-cell layers. This method enables highly efficient culturing of hiPSCs and use of entire undifferentiated portions without having to pick deviated cells manually. This simple and readily reproducible culture strategy is a potentially useful tool for improving the robust and scalable maintenance of undifferentiated hiPSC cultures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hypolipidemic effect of MeOH extract of Bambusae Caulis in Taeniam in hyperlipidemia induced by Triton WR-1339 and high cholesterol diet in rats.

PubMed

Ham, Inhye; Yang, Gabsik; Lee, Jaejun; Lee, Kyung-Jin; Choi, Ho-Young

2009-01-01

Hyperlipidemia has been implicated in atherosclerosis which is the leading cause of death among world population and resulting from lipid metabolic changes is a major cause of atherosclerosis. Bambusae Caulis in Taeniam belongs to Bambusaceae is the stem of Phyllostachys nigra (Lodd.) Munro var. henonis (Bean) Stapf of Phyllostachys bambusoides Siebold et Zuccarini, the perennial evergreen tree. The green middle layer of stem is dried in string-shape I shadow after the bark had been removed. In this study, the effects of middle layer of PN, PB, PP, and BCT on rat with hyperlipidemia, induced by Triton WR-1339 and high cholesterol diet were investigated. We measured plasma levels of triglyceride, total cholesterol, low-density lipoprotein (LDL)-cholesterol, and high-density lipoprotein (HDL)-cholesterol as measure of its hyperlipidemic effects. As a result, all of the Bambusae Caulis in Taeniam was reduced total cholesterol, LDL. Inhibition rate on LDL-oxidation, hACAT-1, and hACAT-2 was increased dose-dependently. Therefore all of the Bambusae Caulis in Taeniam is a good candidate for the treatment on Triton WR-1339 and high cholesterol diet-induced blood circulatory disorders, obesity, and hyperlipidemia.

Measuring urban tree loss dynamics across residential landscapes.

PubMed

Ossola, Alessandro; Hopton, Matthew E

2018-01-15

The spatial arrangement of urban vegetation depends on urban morphology and socio-economic settings. Urban vegetation changes over time because of human management. Urban trees are removed due to hazard prevention or aesthetic preferences. Previous research attributed tree loss to decreases in canopy cover. However, this provides little information about location and structural characteristics of trees lost, as well as environmental and social factors affecting tree loss dynamics. This is particularly relevant in residential landscapes where access to residential parcels for field surveys is limited. We tested whether multi-temporal airborne LiDAR and multi-spectral imagery collected at a 5-year interval can be used to investigate urban tree loss dynamics across residential landscapes in Denver, CO and Milwaukee, WI, covering 400,705 residential parcels in 444 census tracts. Position and stem height of trees lost were extracted from canopy height models calculated as the difference between final (year 5) and initial (year 0) vegetation height derived from LiDAR. Multivariate regression models were used to predict number and height of tree stems lost in residential parcels in each census tract based on urban morphological and socio-economic variables. A total of 28,427 stems were lost from residential parcels in Denver and Milwaukee over 5years. Overall, 7% of residential parcels lost one stem, averaging 90.87 stems per km 2 . Average stem height was 10.16m, though trees lost in Denver were taller compared to Milwaukee. The number of stems lost was higher in neighborhoods with higher canopy cover and developed before the 1970s. However, socio-economic characteristics had little effect on tree loss dynamics. The study provides a simple method for measuring urban tree loss dynamics within and across entire cities, and represents a further step toward high resolution assessments of the three-dimensional change of urban vegetation at large spatial scales. Published by Elsevier B.V.

Long-term survivorship of the Corail™ standard stem.

PubMed

Louboutin, L; Viste, A; Desmarchelier, R; Fessy, M-H

2017-11-01

The Corail™ stem, which was first introduced in 1986, has since been modified twice: first to make the neck thinner and then to change the location of the laser markings. The survival and complications of the first-generation straight, titanium, hydroxyapatite-coated stem are known; however, there is little specific information about the latest-generation stem. This led us to conduct a retrospective study to determine the: (1) long-term survival; (2) clinical and radiographic outcomes; (3) complications; and (4) risk factors for revision of the newest Corail™ stem. The newest Corail™ AMT (Articul/EZE™ Mini Taper) standard stem has comparable survival to prior models. This single-center, retrospective study included 133 patients (140 hips), who underwent primary total hip arthroplasty (THA), between January and December 2004, in which a Corail™ Standard stem was implanted using a posterolateral approach. Patients who underwent revision THA, THA due to femoral neck fracture or who received lateralized (offset) stems were excluded. The mean age at the time of THA was 69±13 years [35-92] in 85 men (61%) and 55 women (39%) who had a mean BMI of 27kg/m 2 ±11 [16-39]. At the latest follow-up, 32 patients (32 hips) had died and 8 patients (8 hips) had less than 3 years' follow-up, thus were not included in the clinical evaluation. The Merle d'Aubigné (PMA) score was collected. The stem's survivorship was calculated using the Kaplan-Meier method with revision for aseptic loosening and revision or implant removal for any reason as the end-points. The Cox model was used to analyze risk factors for revision. The mean follow-up was 10±3 years [3-12]. The PMA score was 12±2.6 [5-17] preoperatively and 16±2.7 [7-18] at the last follow-up (P<0.00001). Eighteen complications (12.8%) were recorded at the last follow-up. There were 15 early complications: 6 dislocations, 5 calcar fractures (4 treated by wire cerclage and 1 by stem change plus wire cerclage), 2 greater trochanter fractures (treated non-surgically) and 2 cases of sciatic nerve palsy. There were 3 late complications: 2 cases of iliopsoas irritation and 1 ceramic insert fracture. Stem survival for surgical revision due to aseptic loosening was 98% (95% CI: [0.96-1]). At 12 years, 95% of stems had not been revised or removed (95% CI: [0.92-0.99]). Being less than 58 years of age at the time of surgery was the only risk factor significantly associated with stem revision for any reason (P=0.04). Survival of the Corail™ Standard stem is similar to that of previous generation stems. The changes made in this stem solved the neck failure problem and did not induce new complications. Level IV (retrospective study). Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Correlative controls of senescence and plant death in Arabidopsis thaliana (Brassicaceae).

PubMed

Noodén, L D; Penney, J P

2001-11-01

Like most monocarpic plants, longevity of Arabidopsis thaliana plants is controlled by the reproductive structures; however, they appear to work differently from most dicots studied. Neither male- and female-sterility mutations (ms1-1 and bell1, respectively) nor surgical removal of the stems with inflorescences (bolts) at various stages significantly increased the longevity of individual rosette leaves, yet the mutants and treated plants lived 20-50 d longer, measured by the death of the last rosette and/or the last cauline leaf. A series of growth mutations (clv2-4, clv3-2, det3, vam1 enh, and dark green) also increased plant longevity by 20-30 d but did not delay the overall development of the plants. The mutations prolonged plant life through the production of new leaves and stems with inflorescences (bolts) rather than by extending leaf longevity. In growing stems, the newly-formed leaves may induce senescence in the older leaves; however, removal of the younger leaves did not significantly increase the life of the older leaves on the compressed stems of Arabidopsis. Since plants that produce more bolts also live longer, the reproductive load (dry weight) of the bolts did not seem to drive leaf or whole plant senescence here. The developing reproductive structures caused the death of the plant by preventing regeneration of leaves and bolts, which are green and presumably photosynthetic. They also exerted a correlative control (repression) on the development of additional reproductive structures.

Modular to Monoblock: Difficulties of Detaching the M(2)a-Magnum(TM) Head Are Common in Metal-on-metal Revisions.

PubMed

Mäntymäki, Heikki; Mäkelä, Keijo T; Vahlberg, Tero; Hirviniemi, Joni; Niinimäki, Tuukka

2016-09-01

Modern hip implants typically feature modular heads, which allow for easy exchange and removal from the femoral stem at the time of revision. However, owing to fretting, corrosion, or cold welding, the modular head may be difficult or impossible to separate from the underlying trunnion, especially if the implant has titanium interfaces between the head and the stem. We have repeatedly encountered difficulty removing the titanium sleeve adapter in the M(2)a-Magnum(TM) implant. Although the manufacturer warns about this complication and cases with these difficulties have been reported to the United States FDA, we believed this topic is important to study, because the frequency of difficulties in head removal is unknown and the complications related to this event have not been characterized. We asked: (1) Do revisions of M(2)a-Magnum(TM) implants differ from those of M(2)a-38(TM) implants in terms of ease of removal of the femoral head? (2) In cases where difficulty with M(2)a-Magnum(TM) head removal occurred, was the operative time, bleeding, risk of periprosthetic fracture, or joint infection increased compared with cases where the M(2)a-Magnum(TM) head was removed without difficulties? Between 2004 and 2014, we revised 296 THAs with metal-on-metal implants that involved M(2)a-Magnum(TM) (123) or M(2)a-38(TM) heads (88); of those, 84 were planned to include a femoral stem revision and insufficient data were available for three operations, so they were excluded from this analysis, leaving 124 THAs in the current retrospective study (70 THAs with M(2)a-Magnum(TM) and 54 THAs with M(2)a-38(TM) heads).The method of modular head removal, any difficulties removing the femoral head from the trunnion, operation time, and complications were recorded based on chart review. All the observed problems of detaching the head or taper adapter were among M(2)a-Magnum(TM) heads; there were no problems detaching the head in revisions of the M(2)a-38(TM) implant. In 29% (20 of 70) of revisions of the M(2)a-Magnum(TM) implant, the modular head could not be detached by knocking it with a punch and a mallet. Seventeen percent (12 of 70) of hips needed an unplanned stem revision owing to difficulties with head removal. In revisions of the M(2)a-Magnum(TM) implant that experienced head-removal problems, the median operative time was longer (144 minutes; range, 75-274 minutes) and bleeding was greater (725 mL; range, 300-2200 mL) compared with revisions of the M(2)a-Magnum(TM) implant without head removal problems (77 minutes, range, 33-197 minutes, p < 0.001; 475 mL, range, 50-1500 mL, p = 0.004). With the numbers available, we did not see differences in terms of the proportion of patients experiencing major complications (periprosthetic fracture or postoperative infections) between the groups (difficult versus easy; 25% [five of 20] versus 8% [four of 50]; odds ratio, 3.8 [95% CI, 0.9-16.2], p = 0.067). The titanium-titanium taper junction can be very difficult to separate during revision THAs, and if not anticipated, this problem can result in larger and more complicated revision procedures in patients who have the M(2)a-Magnum(TM) implant. Although the global use of metal-on-metal implants in THAs has decreased dramatically during the last several years, many thousands remain in service and therefore still might require revision. It is crucial to be prepared with special tools, including a femoral head extraction tool and diamond saw. The patient has to be informed of the possibility of a more extensive operation than preoperatively planned. Level III, therapeutic study.

7 CFR 30.3 - Unstemmed.

Code of Federal Regulations, 2012 CFR

2012-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.3 Unstemmed. A form of leaf tobacco consisting of a collection of leaves from which the stems or midribs have not been removed, including leaf-scrap. ...

7 CFR 30.3 - Unstemmed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.3 Unstemmed. A form of leaf tobacco consisting of a collection of leaves from which the stems or midribs have not been removed, including leaf-scrap. ...

7 CFR 30.3 - Unstemmed.

Code of Federal Regulations, 2014 CFR

2014-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.3 Unstemmed. A form of leaf tobacco consisting of a collection of leaves from which the stems or midribs have not been removed, including leaf-scrap. ...

7 CFR 30.3 - Unstemmed.

Code of Federal Regulations, 2013 CFR

2013-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.3 Unstemmed. A form of leaf tobacco consisting of a collection of leaves from which the stems or midribs have not been removed, including leaf-scrap. ...

7 CFR 30.3 - Unstemmed.

Code of Federal Regulations, 2011 CFR

2011-01-01

... AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.3 Unstemmed. A form of leaf tobacco consisting of a collection of leaves from which the stems or midribs have not been removed, including leaf-scrap. ...

Wearable ear EEG for brain interfacing

NASA Astrophysics Data System (ADS)

Schroeder, Eric D.; Walker, Nicholas; Danko, Amanda S.

2017-02-01

Brain-computer interfaces (BCIs) measuring electrical activity via electroencephalogram (EEG) have evolved beyond clinical applications to become wireless consumer products. Typically marketed for meditation and neu- rotherapy, these devices are limited in scope and currently too obtrusive to be a ubiquitous wearable. Stemming from recent advancements made in hearing aid technology, wearables have been shrinking to the point that the necessary sensors, circuitry, and batteries can be fit into a small in-ear wearable device. In this work, an ear-EEG device is created with a novel system for artifact removal and signal interpretation. The small, compact, cost-effective, and discreet device is demonstrated against existing consumer electronics in this space for its signal quality, comfort, and usability. A custom mobile application is developed to process raw EEG from each device and display interpreted data to the user. Artifact removal and signal classification is accomplished via a combination of support matrix machines (SMMs) and soft thresholding of relevant statistical properties.

Zinc accumulation in plant species indigenous to a Portuguese polluted site: relation with soil contamination.

PubMed

Marques, Ana P G C; Rangel, António O S S; Castro, Paula M L

2007-01-01

The levels of zinc accumulated by roots, stems, and leaves of two plant species, Rubus ulmifolius and Phragmites australis, indigenous to the banks of a stream in a Portuguese contaminated site were investigated in field conditions. R. ulmifolius, a plant for which studies on phytoremediation potential are scarce, dominated on the right side of the stream, while P. australis proliferated on the other bank. Heterogeneous Zn concentrations were found along the banks of the stream. Zn accumulation in both species occurred mainly in the roots, with poor translocation to the aboveground sections. R. ulmifolius presented Zn levels in the roots ranging from 142 to 563 mg kg(-1), in the stems from 35 to 110 mg kg(-1), and in the leaves from 45 to 91 mg kg(-1), vs. average soil total Zn concentrations varying from 526 to 957 mg kg(-1). P. australis showed Zn concentrations in the roots from 39 to 130 mg kg(-1), in the stems from 31 to 63 mg kg(-1), and in the leaves from 37 to 83 mg kg(-1), for the lower average soil total Zn levels of 138 to 452 mg kg(-1) found on the banks where they proliferated. Positive correlations were found between the soil total, available and extractable Zn fractions, and metal accumulation in the roots and leaves of R. ulmifolius and in the roots and stems of P. australis. The use of R. ulmifolius and P. australis for phytoextraction purposes does not appear as an effective method of metal removing, but these native metal tolerant plant species may be used to reduce the effects of soil contamination, avoiding further Zn transfer to other environmental compartments.

Neurochemical excitation of propriospinal neurons facilitates locomotor command signal transmission in the lesioned spinal cord.

PubMed

Zaporozhets, Eugene; Cowley, Kristine C; Schmidt, Brian J

2011-06-01

Previous studies of the in vitro neonatal rat brain stem-spinal cord showed that propriospinal relays contribute to descending transmission of a supraspinal command signal that is capable of activating locomotion. Using the same preparation, the present series examines whether enhanced excitation of thoracic propriospinal neurons facilitates propagation of the locomotor command signal in the lesioned spinal cord. First, we identified neurotransmitters contributing to normal endogenous propriospinal transmission of the locomotor command signal by testing the effect of receptor antagonists applied to cervicothoracic segments during brain stem-induced locomotor-like activity. Spinal cords were either intact or contained staggered bilateral hemisections located at right T1/T2 and left T10/T11 junctions designed to abolish direct long-projecting bulbospinal axons. Serotonergic, noradrenergic, dopaminergic, and glutamatergic, but not cholinergic, receptor antagonists blocked locomotor-like activity. Approximately 73% of preparations with staggered bilateral hemisections failed to generate locomotor-like activity in response to electrical stimulation of the brain stem alone; such preparations were used to test the effect of neuroactive substances applied to thoracic segments (bath barriers placed at T3 and T9) during brain stem stimulation. The percentage of preparations developing locomotor-like activity was as follows: 5-HT (43%), 5-HT/N-methyl-D-aspartate (NMDA; 33%), quipazine (42%), 8-hydroxy-2-(di-n-propylamino)tetralin (20%), methoxamine (45%), and elevated bath K(+) concentration (29%). Combined norepinephrine and dopamine increased the success rate (67%) compared with the use of either agent alone (4 and 7%, respectively). NMDA, Mg(2+) ion removal, clonidine, and acetylcholine were ineffective. The results provide proof of principle that artificial excitation of thoracic propriospinal neurons can improve supraspinal control over hindlimb locomotor networks in the lesioned spinal cord.

Removal of trimethylamine (fishy odor) by C₃ and CAM plants.

PubMed

Boraphech, Phattara; Thiravetyan, Paitip

2015-08-01

From screening 23 plant species, it was found that Pterocarpus indicus (C3) and Sansevieria trifasciata (crassulacean acid metabolism (CAM)) were the most effective in polar gaseous trimethylamine (TMA) uptake, reaching up to 90% uptake of initial TMA (100 ppm) within 8 h, and could remove TMA at cycles 1-4 without affecting photosystem II (PSII) photochemistry. Up to 55 and 45% of TMA was taken up by S. trifasciata stomata and leaf epicuticular wax, respectively. During cycles 1-4, interestingly, S. trifasciata changed its stomata apertures, which was directly induced by gaseous TMA and light treatments. In contrast, for P. indicus the leaf epicuticular wax and stem were the major pathways of TMA removal, followed by stomata; these pathways accounted for 46, 46, and 8%, respectively, of TMA removal percentages. Fatty acids, particularly tetradecanoic (C14) acid and octadecanoic (C18) acid, were found to be the main cuticular wax components in both plants, and were associated with TMA removal ability. Moreover, the plants could degrade TMA via multiple metabolic pathways associated with carbon/nitrogen interactions. In CAM plants, one of the crucial pathways enabled 78% of TMA to be transformed directly to dimethylamine (DMA) and methylamine (MA), which differed from C3 plant pathways. Various metabolites were also produced for further detoxification and mineralization so that TMA was completely degraded by plants.

Incorporating structural analysis in a quantum dot Monte-Carlo model

NASA Astrophysics Data System (ADS)

Butler, I. M. E.; Li, Wei; Sobhani, S. A.; Babazadeh, N.; Ross, I. M.; Nishi, K.; Takemasa, K.; Sugawara, M.; Peyvast, Negin; Childs, D. T. D.; Hogg, R. A.

2018-02-01

We simulate the shape of the density of states (DoS) of the quantum dot (QD) ensemble based upon size information provided by high angle annular dark field scanning transmission electron microscopy (HAADF STEM). We discuss how the capability to determined the QD DoS from micro-structural data allows a MonteCarlo model to be developed to accurately describe the QD gain and spontaneous emission spectra. The QD DoS shape is then studied, with recommendations made via the effect of removing, and enhancing this size inhomogeneity on various QD based devices is explored.

Evaluating the behavior of cultured sertoli cells in the presence and absence of spermatogonial stem cell

PubMed Central

Jabarpour, Masoome

2018-01-01

Background The complex process of spermatogenesis is regulated by various factors. Several studies have been conducted to proliferate cells involved in the spermatogenesis process, in culture by used growth factors, different hormones and feeder cells. This study was conducted to evaluate the role of Sertoli cells on gene expression of fibroblast growth factor (FGF2) and glial cell derived neurotrophic factor (GDNF) after removal of spermatogonial stem cells (SSCs) from the culture medium. Methods Following isolation, bovine SSCs were co-cultured with Sertoli cells and follicular stimulating hormone (FSH) for 12 days. In the treatment group, SSCs were removed from the culture medium; in the control group no intervention was done in the culture. Colony formation of SSCs was evaluated by using an inverted microscope. Then, the expression of factors genes were assessed by quantitative RT-PCR. Data was analyzed by using paired-samples t-test. Results The results showed that removal of SSCs led to the increase in expression of GDNF and FGF2. These findings suggest that loss of SSCs population or decline in its population leads to changing in behavior of somatic cells which forming niche and consequently stimulates self-renewal and inhibits differentiation of SSCs. Conclusions The present study showed that removal of SSCs from the culture medium could be a model for damage to SSCs; the results revealed that niche cells respond to SSCs removal by upregulation of FGF2 and GDNF to stimulate self-renewal of SSCs and abrogation of differentiation. PMID:29430457

Loss of quiescence and self-renewal capacity of hematopoietic stem cell in an in vitro leukemic niche.

PubMed

Vanegas, Natalia-Del Pilar; Vernot, Jean-Paul

2017-01-01

Leukemic and mesenchymal stem cells interact in the leukemic microenvironment and affect each other differently. This interplay has also important implications for the hematopoietic stem cell (HSC) biology and function. This study evaluated human HSC self-renewal potential and quiescence in an in vitro leukemic niche without leukemic cells. A leukemic niche was established by co-culturing mesenchymal stem cells with a fresh conditioned medium obtained from a leukemic (REH) cell line. After 3 days, the REH-conditioned medium was removed and freshly isolated CD34+ at a density of up to 100,000 cells/ml were added to the leukemic niche. CD34+ cell evaluations (cell cycle, self-renewal gene expression and migration capacity) were performed after 3 further days of co-culture. Additionally, we preliminary investigated the soluble factors present in the leukemic niche and their effect on the mesenchymal stem cells. Statistical significance was assessed by Student's t test or the nonparametric test Kolmogorov-Smirnov. By co-culturing normal mesenchymal stem cells with the REH-conditioned medium we showed that hematopoietic stem cells, normally in a quiescent state, enter cell cycle and proliferate. This loss of quiescence was accompanied by an increased expression of Ki-67 and c-Myc, two well-known cell proliferation-associated markers. Two central regulators of quiescence GATA2 and p53 were also down regulated. Importantly, two genes involved in HSC self-renewal, Klf4 and the histone-lysine N -methyltransferase enzyme Ezh2, were severely affected. On the contrary, c-Kit expression, the stem cell factor receptor, was upregulated in hematopoietic stem cells when compared to the normal niche. Interestingly, mesenchymal stem cells incubated with the REH-conditioned medium stopped growing, showed a flattened morphology with the appearance of small vacuoles, and importantly, became positive for the senescence-associated beta-galactosidase activity. Evaluation of the leukemic-conditioned medium showed increased IL-6 and IL-8, suggesting that these cytokines could be responsible for the observed changes. Our results showed that quiescence and self-renewal are severely affected in this leukemic niche. This in vitro leukemic niche, established without leukemic cells, will facilitate HSC gene expression evaluation and the development of therapeutic agents aimed to neutralize soluble factors and the cell signaling pathways involved in HSC alterations.

Operation DOMINIC. Project Stemwinder

DTIC Science & Technology

1985-09-01

b.. n removed in order to «ake th. information av.ilai" o’ an ancl...if ied, open publication ba.i^ to «"**" «"ted it! Th. .ffort to declassify this...activity as a function of height in tht stem for air burats, Tht rathtr largt scatter in the data may bt attributed to several iactorj. Ic apptara ChaC ...appun rcaionably certain ChaC for alrbursts las« than 1 percent of the total activity Is present In the stem and less than 0.1 percent stabilises

6. VIEW OF BOW OF VESSEL FROM STARBOARD SIDE, SHOWING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. VIEW OF BOW OF VESSEL FROM STARBOARD SIDE, SHOWING DOCKING CREW PREPARING TO REMOVE FOREFOOT FROM VESSEL'S STEM IN ORDER TO DRAW VESSEL OFF LIFT DOCK - Bugeye "Louise Travers", Intersection of Routes 2 & 4, Solomons, Calvert County, MD

Ewing Sarcoma Treatment (PDQ®)—Patient Version

Cancer.gov

Ewing sarcoma treatment usually begins with chemotherapy and/or radiation followed by surgery to remove any remaining cancer. Treatment options for recurrent sarcoma include targeted therapy and high-dose chemotherapy with stem cell transplant. Learn more in this expert-reviewed summary.

Quantitative HAADF STEM of SiGe in presence of amorphous surface layers from FIB preparation.

PubMed

Grieb, Tim; Tewes, Moritz; Schowalter, Marco; Müller-Caspary, Knut; Krause, Florian F; Mehrtens, Thorsten; Hartmann, Jean-Michel; Rosenauer, Andreas

2018-01-01

The chemical composition of four Si 1-x Ge x layers grown on silicon was determined from quantitative scanning transmission electron microscopy (STEM). The chemical analysis was performed by a comparison of the high-angle annular dark field (HAADF) intensity with multislice simulations. It could be shown that amorphous surface layers originating from the preparation process by focused-ion beam (FIB) at 30 kV have a strong influence on the quantification: the local specimen thickness is overestimated by approximately a factor of two, and the germanium concentration is substantially underestimated. By means of simulations, the effect of amorphous surface layers on the HAADF intensity of crystalline silicon and germanium is investigated. Based on these simulations, a method is developed to analyze the experimental HAADF-STEM images by taking the influence of the amorphous layers into account which is done by a reduction of the intensities by multiplication with a constant factor. This suggested modified HAADF analysis gives germanium concentrations which are in agreement with the nominal values. The same TEM lamella was treated with low-voltage ion milling which removed the amorphous surface layers completely. The results from subsequent quantitative HAADF analyses are in agreement with the nominal concentrations which validates the applicability of the used frozen-lattice based multislice simulations to describe the HAADF scattering of Si 1-x Ge x in STEM. Copyright © 2017 Elsevier B.V. All rights reserved.

Neural Stem Cells Expressing bFGF Reduce Brain Damage and Restore Sensorimotor Function after Neonatal Hypoxia-Ischemia.

PubMed

Ye, Qingsong; Wu, Yanqing; Wu, Jiamin; Zou, Shuang; Al-Zaazaai, Ali Ahmed; Zhang, Hongyu; Shi, Hongxue; Xie, Ling; Liu, Yanlong; Xu, Ke; He, Huacheng; Zhang, Fabiao; Ji, Yiming; He, Yan; Xiao, Jian

2018-01-01

Neonatal hypoxia-ischemia (HI) causes severe brain damage and significantly increases neonatal morbidity and mortality. Increasing evidences have verified that stem cell-based therapy has the potential to rescue the ischemic tissue and restore function via secreting growth factors after HI. Here, we had investigated whether intranasal neural stem cells (NSCs) treatment improves the recovery of neonatal HI, and NSCs overexpressing basic fibroblast growth factor (bFGF) has a better therapeutic effect for recovery than NSCs treatment only. We performed permanent occlusion of the right common carotid artery in 9-day old ICR mice as animal model of neonatal hypoxia-ischemia. At 3 days post-HI, NSC, NSC-GFP, NSC-bFGF and vehicle were delivered intranasally. To determine the effect of intranasal NSC, NSC-GFP and NSC-bFGF treatment on recovery after HI, we analyzed brain damage, sensor-motor function and cell differentiation. It was observed that intranasal NSC, NSC-GFP and NSC-bFGF treatment decreased gray and white matter loss area in comparison with vehicle-treated mouse. NSC, NSC-GFP and NSC-bFGF treatment also significantly improved sensor motor function in cylinder rearing test and adhesive removal test, however, NSC-bFGF-treatment was more effective than NSC-treatment in the improvement of somatosensory function. Furthermore, compared with NSC and NSC-GFP, NSC-bFGF treatment group appeared to differentiate into more neurons. Taken together, intranasal administration of NSCs is a promising therapy for treatment of neonatal HI, but NSCs overexpressing bFGF promotes the survival and differentiation of NSCs, and consequently achieves a better therapeutic effect in improving recovery after neonatal HI. © 2018 The Author(s). Published by S. Karger AG, Basel.

Regional impacts of Atlantic Forest deforestation on climate and vegetation dynamics

NASA Astrophysics Data System (ADS)

Holm, J. A.; Chambers, J. Q.

2012-12-01

The Brazilian Atlantic Forest was a large and important forest due to its high biodiversity, endemism, range in climate, and complex geography. The original Atlantic Forest was estimated to cover 150 million hectares, spanning large latitudinal, longitudinal, and elevation gradients. This unique environment helped contribute to a diverse assemblage of plants, mammals, birds, and reptiles. Unfortunately, due to land conversion into agriculture, pasture, urban areas, and increased forest fragmentation, only ~8-10% of the original Atlantic Forest remains. Tropical deforestation in the Americas can have considerable effects on local to global climates, and surrounding vegetation growth and survival. This study uses a fully coupled, global climate model (Community Earth System Model, CESM v.1.0.1) to simulate the full removal of the historical Atlantic Forest, and evaluate the regional climatic and vegetation responses due to deforestation. We used the fully coupled atmosphere and land surface components in CESM, and a partially interacting ocean component. The vegetated grid cell portion of the land surface component, the Community Landscape Model (CLM), is divided into 4 of 16 plant functional types (PFTs) with vertical layers of canopy, leaf area index, soil physical properties, and interacting hydrological features all tracking energy, water, and carbon state and flux variables, making CLM highly capable in predicting the complex nature and outcomes of large-scale deforestation. The Atlantic Forest removal (i.e. deforestation) was conducted my converting all woody stem PFTs to grasses in CLM, creating a land-use change from forest to pasture. By comparing the simulated historical Atlantic Forest (pre human alteration) to a deforested Atlantic Forest (close to current conditions) in CLM and CESM we found that live stem carbon, NPP (gC m-2 yr-1), and other vegetation dynamics inside and outside the Atlantic Forest region were largely altered. In addition to vegetation effects, regional surface air temperature (C°), precipitation (mm day-1), and emitted longwave radiation (W m-2) were highly affected in the location of the removed forest, and throughout surrounding areas of South America. For example climate patterns of increased temperature and decreased precipitation were affected as far as the Amazon Forest region. The use of fully coupled global climate and terrestrial models to study the effects of large-scale forest removal have been rarely applied. This study successfully showed the valuation of an important tropical forest, and the consequences of large deforestation through the reporting of complex earth-atmosphere interactions between vegetation dynamics and climate.

Asparagus stem as a new lignocellulosic biomass feedstock for anaerobic digestion: increasing hydrolysis rate, methane production and biodegradability by alkaline pretreatment.

PubMed

Chen, Xiaohua; Gu, Yu; Zhou, Xuefei; Zhang, Yalei

2014-07-01

Recently, anaerobic digestion of lignocellulosic biomass for methane production has attracted considerable attention. However, there is little information regarding methane production from asparagus stem, a typical lignocellulosic biomass, by anaerobic digestion. In this study, alkaline pretreatment of asparagus stem was investigated for its ability to increase hydrolysis rate and methane production and to improve biodegradability (BD). The hydrolysis rate increased with increasing NaOH dose, due to higher removal rates of lignin and hemicelluloses. However, the optimal NaOH dose was 6% (w/w) according to the specific methane production (SMP). Under this condition, the SMP and the technical digestion time of the NaOH-treated asparagus stem were 242.3 mL/g VS and 18 days, which were 38.4% higher and 51.4% shorter than those of the untreated sample, respectively. The BD was improved from 40.1% to 55.4%. These results indicate that alkaline pretreatment could be an efficient method for increasing methane production from asparagus stem. Copyright © 2014 Elsevier Ltd. All rights reserved.

40 CFR 180.475 - Difenoconazole; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., straw 0.05 Beet, sugar 0.3 Beet, sugar, dried pulp 1.9 Brassica, head and stem, subgroup 5A 1.9 Brassica..., oil 25 Corn, sweet, forage 0.01 Corn, sweet, kernel plus cob with husks removed 0.01 Corn, sweet...

40 CFR 180.475 - Difenoconazole; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., straw 0.05 Beet, sugar 0.3 Beet, sugar, dried pulp 1.9 Brassica, head and stem, subgroup 5A 1.9 Brassica..., oil 25 Corn, sweet, forage 0.01 Corn, sweet, kernel plus cob with husks removed 0.01 Corn, sweet...

Harvesting Productionin Uneven-Aged Loblolly-Shortleaf Pine Stands:The Crossett Farm Forestry Forties

Treesearch

R. Kluender; B. Stokes; S. Woodfin

1992-01-01

Twostands managed using uneven-aged techniques werehar- vested aspar-t of a5-year entry schedule. Felling and skidding productivity varied significantly with average stem diameter and volume and was affected by diameter distribution of the removed material.

Ciliary neurotrophic factor promotes the activation of corneal epithelial stem/progenitor cells and accelerates corneal epithelial wound healing.

PubMed

Zhou, Qingjun; Chen, Peng; Di, Guohu; Zhang, Yangyang; Wang, Yao; Qi, Xia; Duan, Haoyun; Xie, Lixin

2015-05-01

Ciliary neurotrophic factor (CNTF), a well-known neuroprotective cytokine, has been found to play an important role in neurogenesis and functional regulations of neural stem cells. As one of the most innervated tissue, however, the role of CNTF in cornea epithelium remains unclear. This study was to explore the roles and mechanisms of CNTF in the activation of corneal epithelial stem/progenitor cells and wound healing of both normal and diabetic mouse corneal epithelium. In mice subjecting to mechanical removal of corneal epithelium, the corneal epithelial stem/progenitor cell activation and wound healing were promoted by exogenous CNTF application, while delayed by CNTF neutralizing antibody. In cultured corneal epithelial stem/progenitor cells, CNTF enhanced the colony-forming efficiency, stimulated the mitogenic proliferation, and upregulated the expression levels of corneal epithelial stem/progenitor cell-associated transcription factors. Furthermore, the promotion of CNTF on the corneal epithelial stem/progenitor cell activation and wound healing was mediated by the activation of STAT3. Moreover, in diabetic mice, the content of CNTF in corneal epithelium decreased significantly when compared with that of normal mice, and the supplement of CNTF promoted the diabetic corneal epithelial wound healing, accompanied with the advanced activation of corneal epithelial stem/progenitor cells and the regeneration of corneal nerve fibers. Thus, the capability of expanding corneal epithelial stem/progenitor cells and promoting corneal epithelial wound healing and nerve regeneration indicates the potential application of CNTF in ameliorating limbal stem cell deficiency and treating diabetic keratopathy. © 2014 AlphaMed Press.

Chemotherapeutic Drugs: DNA Damage and Repair in Glioblastoma.

PubMed

Annovazzi, Laura; Mellai, Marta; Schiffer, Davide

2017-05-26

Despite improvements in therapeutic strategies, glioblastoma (GB) remains one of the most lethal cancers. The presence of the blood-brain barrier, the infiltrative nature of the tumor and several resistance mechanisms account for the failure of current treatments. Distinct DNA repair pathways can neutralize the cytotoxicity of chemo- and radio-therapeutic agents, driving resistance and tumor relapse. It seems that a subpopulation of stem-like cells, indicated as glioma stem cells (GSCs), is responsible for tumor initiation, maintenance and recurrence and they appear to be more resistant owing to their enhanced DNA repair capacity. Recently, attention has been focused on the pivotal role of the DNA damage response (DDR) in tumorigenesis and in the modulation of therapeutic treatment effects. In this review, we try to summarize the knowledge concerning the main molecular mechanisms involved in the removal of genotoxic lesions caused by alkylating agents, emphasizing the role of GSCs. Beside their increased DNA repair capacity in comparison with non-stem tumor cells, GSCs show a constitutive checkpoint expression that enables them to survive to treatments in a quiescent, non-proliferative state. The targeted inhibition of checkpoint/repair factors of DDR can contribute to eradicate the GSC population and can have a great potential therapeutic impact aiming at sensitizing malignant gliomas to treatments, improving the overall survival of patients.

Short-term effects of whole-tree and stem-only harvesting on C and N fluxes in two Picea abies stands, Norway

NASA Astrophysics Data System (ADS)

Janne Kjønaas, O.; Clarke, Nicholas; Eldhuset, Toril; Hietala, Ari; Cross, Hugh; Holt Hanssen, Kjersti; Økland, Tonje; Lange, Holger; Frode Nordbakken, Jørn; Røsberg, Ingvald

2015-04-01

Tree harvest and different harvesting methods may affect the soil carbon (C) pool in forest ecosystems. In conventional stem-only timber harvesting (SOH), branches and tops that are left in the forests may contribute to the build-up of the soil carbon pool. In whole-tree harvesting (WTH), inputs of organic matter from branches and tops are strongly reduced. We established field experiments at Gaupen, SE and Vindberg, SW Norway, to study the short-term effects of SOH and WTH on processes affecting the accumulation and loss of soil C. Logging residues on the WTH plots were collected in piles that were removed after 6 months, rendering two sub treatments (WTH-pile and WTH-removal areas). We weighed selected trees and logging residues, surveyed understorey biomass production, quantified pre-harvest soil C and nutrient pools down to 30 cm. Soil respiration was measured and soil water sampled monthly during the growing season, while temperature and moisture were measured continuously. Organic and mineral horizons were incubated at different temperatures to estimate potential C and N mineralization, and deep sequencing of the ITS2 barcode region of fungal DNA was performed on the samples. Litterbags were deployed in the SOH plots. The logging residues amounted to 2.2-2.4 kg C m-2. At Gaupen, the mean in situ soil respiration rates increased following harvest with all treatments, but were significantly higher in WTH-pile and SOH relative to the WTH-removal areas in the first year as well as the fourth year of treatment. The former rates included aboveground decomposing needles and twigs but excluded coarser branches. The observed increase in the WTH-removal areas may be related to decomposing roots, as well as to increased C mineralization partly due to the higher soil temperatures following harvest. Soil temperature was the single most important factor explaining the variability in soil respiration rates over all treatments. At Vindberg, a decrease in soil respiration was observed with all treatments in the second and third years following harvest. At both sites, decomposition of logging residues from needles was more rapid relative to twigs and fine roots. The decomposing residues released a substantial amount of nitrogen which was gradually reflected in the soil water at 30 cm soil depth. A considerable increase in the NO3-N concentration also in the WTH-removal areas in the second year following harvest suggests an increase in N availability from decomposing fine roots and/or soil organic matter. The increased N availability in the WTH-removal areas was supported by results from short term lab incubations of undisturbed soil from the forest floor. The changes in the WTH-removal areas were also reflected in the soil fungal diversity: saprophytic ascomycetes on decaying plant material showed a striking increase in all treatments. For the WTH-removal areas, this may, again, be related to the increased input of root litter; however, the decrease in mycorrhizal basidiomycete species and the vigorous increase of ascomycetes following harvest may also affect the C mineralization of soil organic matter.

Effect of three kinds of surfactants and β-cyclodextrin on the phytoremediation of BDE-209 contaminated sediment

NASA Astrophysics Data System (ADS)

Zhao, Liangyuan; Guo, Weijie; Zhao, Weihua; Long, Meng; Li, Huan

2017-05-01

Plant-accelerated removal of BDE-209 from sediment by aquatic macrophyte Scirpus validus Vahl in the presence of a cationic-surfactant (CTAB), an anionic-surfactant (SDS), a nonionic-surfactant (Tween 80) and β-cyclodextrin (β-CD) at the concentrations ranged from 300 mg/kg to 1000 mg/kg were investigated. Significantly negative effect were not observed for the growth of S. validus in terms of plant height and stem diatemeter, which indicated that it is preferable for CTAB, SDS, Tween 80 and β-cyclodextrin to be utilized as the BDE-209 phytoremediation amendment. Furthermore, CTAB, SDS and Tween 80 in the certain concentrations significantly enhanced the phytoremediation efficiencies and 11.78-19.33% of increase in BDE-209 removal rates was obtained. Significantly enhance of BDE-209 phytoremediation efficiency was not observed in the added β-CD concentration ranges. Results obtained from this study provided some insight with regard to the feasibility of phytoremediation for BDE-209 contaminated sediments with addition of suitable solubilizers, especially Tween 80.

Flammulina velutipes: An option for "alperujo" use.

PubMed

Rugolo, Maximiliano; Levin, Laura; Lechner, Bernardo Ernesto

Two-phase olive-mill wastes (or "alperujo") exhibit highly phytotoxic properties, mainly due to phenols. A valuable option for alperujo is its agricultural use, provided that no phytotoxic effects occur. The present investigation was aimed at evaluating the efficacy of two strains of the lignin-degrading fungus Flammulina velutipes to colonize alperujo in order to produce edible mushrooms and to achieve its detoxification. Some important cultural characters related to mushroom production (earliness, biological efficiency and quality of basidiomes) were estimated. The production of lignocellulolytic enzymes, phenol removal and detoxification of the substrate was evaluated. High biological efficiencies (70.8%) were obtained at 12°C with F. velutipes strain BAFC 670/06 in a substrate containing poplar wood shavings and 90% of alperujo. The nature of the substrate did not seem to exert an important influence on pileus and stem morphology; nevertheless shortest stems were observed at higher temperatures. Endo-β-1,4-glucanase, endo-β-1,4-xylanase, laccase and Mn-peroxidase activities were detected in the extracts recovered from the solid-state cultures. Both F. velutipes strains were effective in removing the phenolic compounds. The initial concentration in the substrate with 90% alperujo was reduced in the case of F. velutipes BAFC 1763 by 84.31%, and 40.15% by F. velutipes BAFC 670/06. Germinability experiments on Raphanus sativus, showed that alperujo phytotoxicity was significantly reduced by F. velutipes cultures. The experimented changes by the spent mushroom substrate resulting from F. velutipes cultivation with high amount of alperujo would allow its reuse for agricultural purposes. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Enrichment isolation of adipose-derived stem/stromal cells from the liquid portion of liposuction aspirates with the use of an adherent column.

PubMed

Doi, Kentaro; Kuno, Shinichiro; Kobayashi, Akira; Hamabuchi, Takahisa; Kato, Harunosuke; Kinoshita, Kahori; Eto, Hitomi; Aoi, Noriyuki; Yoshimura, Kotaro

2014-03-01

Adipose-derived stem/progenitor cells (ASCs) are typically obtained from the lipoaspirates; however, a smaller number of ASCs can be isolated without enzymatic digestion from the infranatant liposuction aspirate fluid (LAF). We evaluated the effectiveness of an adherent column, currently used to isolate mesenchymal stromal cells from bone marrow, to isolate LAF cells. We applied peripheral blood (PB), PB mixed with cultured ASCs (PB-ASC), and LAF solution to the column and divided it into two fractions, the adherent (positive) and the non-adherent (negative) fractions. We compared this method with hypotonic hemolysis (lysis) for the red blood cell count, nucleated cells count and cell compositions as well as functional properties of isolated mesenchymal cells. The column effectively removed red blood cells, though the removal efficiency was slightly inferior to hemolysis. After column processing of PB-ASC, 60.5% of ASCs (53.2% by lysis) were selectively collected in the positive fraction, and the negative fraction contained almost no ASCs. After processing of LAF solution, nucleated cell yields were comparable between the column and hemolysis; however, subsequent adherent culture indicated that a higher average ASC yield was obtained from the column-positive samples than from the lysis samples, suggesting that the column method may be superior to hemolysis for obtaining viable ASCs. Mesenchymal differentiation and network formation assays showed no statistical differences in ASC functions between the lysis and column-positive samples. Our results suggest that a column with non-woven rayon and polyethylene fabrics is useful for isolating stromal vascular fraction cells from LAF solutions for clinical applications. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Microgravity-Enhanced Stem Cell Selection

NASA Technical Reports Server (NTRS)

Claudio, Pier Paolo; Valluri, Jagan

2011-01-01

Stem cells, both embryonic and adult, promise to revolutionize the practice of medicine in the future. In order to realize this potential, a number of hurdles must be overcome. Most importantly, the signaling mechanisms necessary to control the differentiation of stem cells into tissues of interest remain to be elucidated, and much of the present research on stem cells is focused on this goal. Nevertheless, it will also be essential to achieve large-scale expansion and, in many cases, assemble cells in 3D as transplantable tissues. To this end, microgravity analog bioreactors can play a significant role. Microgravity bioreactors were originally conceived as a tool to study the cellular responses to microgravity. However, the technology can address some of the shortcomings of conventional cell culture systems; namely, the deficiency of mass transport in static culture and high mechanical shear forces in stirred systems. Unexpectedly, the conditions created in the vessel were ideal for 3D cell culture. Recently, investigators have demonstrated the capability of the microgravity bioreactors to expand hematopoietic stem cells compared to static culture, and facilitate the differentiation of umbilical cord stem cells into 3D liver aggregates. Stem cells are capable of differentiating into functional cells. However, there are no reliable methods to induce the stem cells to form specific cells or to gain enough cells for transplantation, which limits their application in clinical therapy. The aim of this study is to select the best experimental setup to reach high proliferation levels by culturing these cells in a microgravity-based bioreactor. In typical cell culture, the cells sediment to the bottom surface of their container and propagate as a one-cell-layer sheet. Prevention of such sedimentation affords the freedom for self-assembly and the propagation of 3D tissue arrays. Suspension of cells is easily achievable using stirred technologies. Unfortunately, in conventional bioreactors, stirring invokes deleterious forces that disrupt cell aggregation and results in cell death. First-generation rotating bioreactors provided rotation on the horizontal axis, which resulted in the suspension of cells without stirring, thus providing a suitable environment to propagate cells without sedimentation to a surface. The rotating wall bioreactors did not provide a way to remove air bubbles that were causing shear and disrupting 3D cultures. Johnson Space Center successfully engineered the hydrofocusing bioreactor (HFB) that resolved the problem of removing the air bubbles from the fluid medium of NASA's rotating-wall space bioreactors. The HFB uses the principle of hydrodynamic focusing that simultaneously produces a low-shear fluid culture environment and a variable hydrofocusing force that can control the movement, location, and removal of suspended cells, tissues, and air bubbles from the bioreactor. The HFB is a rotating, domeshaped cell culture vessel with a centrally located sampling port and an internal viscous spinner. The vessel and spinner can rotate at different speeds either in the same or opposite directions. Rotation of the vessel and viscous interaction at the spinner generate a hydrofocusing force. Adjusting the differential rotation rate between vessel and spinner controls the magnitude of the force.

Relationship between ketamine-induced developmental neurotoxicity and NMDA receptor-mediated calcium influx in neural stem cell-derived neurons.

PubMed

Wang, Cheng; Liu, Fang; Patterson, Tucker A; Paule, Merle G; Slikker, William

2017-05-01

Ketamine, a noncompetitive NMDA receptor antagonist, is used as a general anesthetic and recent data suggest that general anesthetics can cause neuronal damage when exposure occurs during early brain development. To elucidate the underlying mechanisms associated with ketamine-induced neurotoxicity, stem cell-derived models, such as rodent neural stem cells harvested from rat fetuses and/or neural stem cells derived from human induced pluripotent stem cells (iPSC) can be utilized. Prolonged exposure of rodent neural stem cells to clinically-relevant concentrations of ketamine resulted in elevated NMDA receptor levels as indicated by NR1subunit over-expression in neurons. This was associated with enhanced damage in neurons. In contrast, the viability and proliferation rate of undifferentiated neural stem cells were not significantly affected after ketamine exposure. Calcium imaging data indicated that 50μM NMDA did not cause a significant influx of calcium in typical undifferentiated neural stem cells; however, it did produce an immediate elevation of intracellular free Ca 2+ [Ca 2+ ] i in differentiated neurons derived from the same neural stem cells. This paper reviews the literature on this subject and previous findings suggest that prolonged exposure of developing neurons to ketamine produces an increase in NMDA receptor expression (compensatory up-regulation) which allows for a higher/toxic influx of calcium into neurons once ketamine is removed from the system, leading to neuronal cell death likely due to elevated reactive oxygen species generation. The absence of functional NMDA receptors in cultured neural stem cells likely explains why clinically-relevant concentrations of ketamine did not affect undifferentiated neural stem cell viability. Published by Elsevier B.V.

Improving the analysis of NMR spectra tracking pH-induced conformational changes: removing artefacts of the electric field on the NMR chemical shift.

PubMed

Kukić, Predrag; Farrell, Damien; Søndergaard, Chresten R; Bjarnadottir, Una; Bradley, John; Pollastri, Gianluca; Nielsen, Jens Erik

2010-03-01

pH-induced chemical shift perturbations (CSPs) can be used to study pH-dependent conformational transitions in proteins. Recently, an elegant principal component analysis (PCA) algorithm was developed and used to study the pH-dependent structural transitions in bovine beta-lactoglobulin (betaLG) by analyzing its NMR pH-titration spectra. Here, we augment this analysis method by filtering out changes in the NMR chemical shift that stem from effects that are electrostatic in nature. Specifically, we examine how many CSPs can be explained by purely electrostatic effects arising from titrational events in betaLG. The results show that around 20% of the amide nuclei CSPs in betaLG originate exclusively from "through-space" electric field effects. A PCA of NMR data where electric field artefacts have been removed gives a different picture of the pH-dependent structural transitions in betaLG. The method implemented here is well suited to be applied on a whole range of proteins, which experience at least one pH-dependent conformational change. Proteins 2010. (c) 2009 Wiley-Liss, Inc.

Unraveling carbohydrate transport mechanisms in young beech trees (Fagus sylvatica f. purpurea) by 13CO2 efflux measurements from stem and soil

NASA Astrophysics Data System (ADS)

Thoms, Ronny; Muhr, Jan; Keitel, Claudia; Kayler, Zachary; Gavrichkova, Olga; Köhler, Michael; Gessler, Arthur; Gleixner, Gerd

2016-04-01

Transport mechanisms of soluble carbohydrates and diurnal CO2 efflux from tree stems and surrounding soil are well studied. However, the effect of transport carbohydrates on respiration and their interaction with storage processes is largely unknown. Therefore, we performed a set of 13CO2 pulse labeling experiments on young trees of European beech (Fagus sylvatica f. purpurea). We labeled the whole tree crowns in a closed transparent plastic chamber with 99% 13CO2 for 30 min. In one experiment, only a single branch was labeled and removed 36 hours after labeling. In all experiments, we continuously measured the 13CO2 efflux from stem, branch and soil and sampled leaf and stem material every 3 h for 2 days, followed by a daily sampling of leaves in the successive 5 days. The compound specific δ 13C value of extracted soluble carbohydrates from leaf and stem material was measured by high-performance liquid chromatography linked with an isotope ratio mass spectrometer (HPLC-IRMS). The 13CO2 signal from soil respiration occurred only few hours after labeling indicating a very high transport rate of carbohydrates from leaf to roots and to the rhizosphere. The label was continuously depleted within the next 5 days. In contrast, we observed a remarkable oscillating pattern of 13CO2 efflux from the stem with maximum 13CO2 enrichment at noon and minima at night time. This oscillation suggests that enriched carbohydrates are respired during the day, whereas in the night the enriched sugars are not respired. The observed oscillation in stem 13CO2 enrichment remained unchanged even when only single branches were labelled and cut right afterwards. Thus, storage and conversion of carbohydrates only occurred within the stem. The δ13C patterns of extracted soluble carbohydrates showed, that a transformation of transitory starch to carbohydrates and vice versa was no driver of the oscillating 13CO2 efflux from the stem. Carbohydrates might have been transported in the phloem to the location of biosynthesis further to a storage pool from which they are respired during the day. Keywords: 13CO2 efflux, oscillating pattern, carbohydrates, transitory starch

GEOMORPHIC CONTROLS ON C AND N PROCESSING IN A RESTORED URBAN STREAM; POWER POINT PRESENTATION

EPA Science Inventory

Stream channel incision due to hydraulic alteration stemming from urbanization may cause a disconnection between the stream channel and the adjacent floodplain. This disconnection may inhibit removal of nitrate via denitrification and/or stimulate nitrate production through nitr...

Effects of cutting time, stump height, parent tree characteristics, and harvest variables on development of bigleaf maple sprout clumps

USGS Publications Warehouse

Tappeiner, J. C.; Zasada, J.; Maxwell, B.

1996-01-01

In order to determine the effects of stump height, year of cutting, parent-tree size, logging damage, and deer browsing on bigleaf maple (Acer macrophyllum) sprout clump development, maple trees were cut to two stump heights at three different times. Stump height had the greatest impact on sprout clump size. Two years after clearcutting, the sprout clump volume for short stumps was significantly less than that for tall stumps. The sprout clump volume, area, and number of sprouts were significantly less for trees cut 1 and 2 yr before harvest than for trees cut at harvest. Sprout clump size was positively correlated with parent tree stem diameter and stump volume, and negatively correlated with the percentage of bark removed during logging. Browsing had no significant impact on average clump size. Uncut trees produced sprout clumps at their base and epicormic branches along the length of their stems; thus their crown volume averaged four to five times that of cut trees. Cutting maple in clearcuts to low stumps may reduce maple competition with Douglas-fir regeneration and still maintain maple in the next stand.

Effect of bicarbonate on aging and reactivity of nanoscale zerovalent iron (nZVI) toward uranium removal.

PubMed

Hua, Yilong; Wang, Wei; Huang, Xiaoyue; Gu, Tianhang; Ding, Dexin; Ling, Lan; Zhang, Wei-Xian

2018-06-01

Bicarbonate, ubiquitous in natural and waste waters is an important factor regulating the rate and efficiency of pollutant separation and transformation. For example, it can form complexes with U(VI) in the aqueous phase and at the solid-water interface. In this work, we investigated the effect of bicarbonate on the aging of nanoscale zero-valent (nZVI) in the context of U(VI) reduction and removal from wastewater. For fresh nZVI, over 99% aqueous uranium was separated in less than 10 min, of which 83% was reduced from U(VI) to U(IV). When nZVI was aged in water, its activity for U(VI) sequestration and reduction was significantly reduced. Batch experiments showed that for nZVI aged in the presence of 10 mM bicarbonate, only 20.3% uranium was reduced to U(IV) after 6 h reactions. Characterizations of the iron nanoparticles with spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) suggest that in fresh nZVI, uranium was concentrated at the nanoparticle center; whereas in nZVI aged in bicarbonate, uranium was largely deposited on the outer surface of the nanoparticles. Furthermore, aged nZVI without bicarbonate contained more lepidocrocite (γ-FeOOH) while aged nZVI in the presence of bicarbonate had more magnetite/maghemite (Fe 3 O 4 /γ-Fe 2 O 3 ). This could be attributed to the formation of carbonate green rust and pH buffer effect of . Primary mechanisms for U(VI) removal with nZVI include reduction, sorption and/or precipitation. Results demonstrate that bicarbonate alter the aging products of nZVI, and reduces the separation efficiency and reduction capability for uranium removal. Copyright © 2018. Published by Elsevier Ltd.

Chondroitin sulfatases differentially regulate Wnt signaling in prostate stem cells through effects on SHP2, phospho-ERK1/2, and Dickkopf Wnt signaling pathway inhibitor (DKK3)

PubMed Central

Bhattacharyya, Sumit; Feferman, Leo; Tobacman, Joanne K.

2017-01-01

The chondroitin sulfatases N-acetylgalactosamine-4-sulfatase (ARSB) and galactosamine-N-acetyl-6-sulfatase (GALNS) remove either the 4-sulfate group at the non-reducing end of chondroitin 4-sulfate (C4S) and dermatan sulfate, or the 6-sulfate group of chondroitin 6-sulfate, chondroitin 4,6-disulfate (chondroitin sulfate E), or keratan sulfate. In human prostate cancer tissues, the ARSB activity was reduced and the GALNS activity was increased, compared to normal prostate tissue. In human prostate stem cells, when ARSB was reduced by silencing or GALNS was increased by overexpression, activity of SHP2, the ubiquitous non-receptor tyrosine phosphatase, declined, attributable to increased binding of SHP2 with C4S. This led to increases in phospho-ERK1/2, Myc/Max nuclear DNA binding, DNA methyltransferase (DNMT) activity and expression, and methylation of the Dickkopf Wnt signaling pathway inhibitor (DKK)3 promoter and to reduced DKK3 expression. Since DKK3 negatively regulates Wnt/β-catenin signaling, silencing of ARSB or overexpression of GALNS disinhibited (increased) Wnt/β-catenin signaling. These findings indicate that the chondroitin sulfatases can exert profound effects on Wnt-mediated processes, due to epigenetic effects that modulate Wnt signaling. PMID:29245974

Coating carbon nanotubes with humic acid using an eco-friendly mechanochemical method: Application for Cu(II) ions removal from water and aquatic ecotoxicity.

PubMed

Côa, Francine; Strauss, Mathias; Clemente, Zaira; Rodrigues Neto, Laís L; Lopes, Josias R; Alencar, Rafael S; Souza Filho, Antônio G; Alves, Oswaldo L; Castro, Vera Lúcia S S; Barbieri, Edison; Martinez, Diego Stéfani T

2017-12-31

In this work, industrial grade multi-walled carbon nanotubes (MWCNT) were coated with humic acid (HA) for the first time by means of a milling process, which can be considered an eco-friendly mechanochemical method to prepare materials and composites. The HA-MWCNT hybrid material was characterized by atomic force microscopy (AFM), scanning electron microscopies (SEM and STEM), X-ray photoelectron spectroscopy (XPS), termogravimetric analysis (TGA), and Raman spectroscopy. STEM and AFM images demonstrated that the MWCNTs were efficiently coated by the humic acid, thus leading to an increase of 20% in the oxygen content at the nanotube surface as observed by the XPS data. After the milling process, the carbon nanotubes were shortened as unveiled by SEM images and the values of ID/IG intensity ratio increased due to shortening of the nanotubes and increasing in the number defects at the graphitic structure of carbon nanotubes walls. The analysis of TGA data showed that the quantity of the organic matter of HA on the nanotube surface was 25%. The HA coating was responsible to favor the dispersion of MWCNTs in ultrapure water (i.e. -42mV, zeta-potential value) and to improve their capacity for copper removal. HA-MWCNTs hybrid material adsorbed 2.5 times more Cu(II) ions than oxidized MWCNTs with HNO 3 , thus evidencing that it is a very efficient adsorbent material for removing copper ions from reconstituted water. The HA-MWCNTs hybrid material did not show acute ecotoxicity to the tested aquatic model organisms (Hydra attenuata, Daphnia magna, and Danio rerio embryos) up to the highest concentration evaluated (10mgL -1 ). The results allowed concluding that the mechanochemical method is effective to coat carbon nanotubes with humic acid, thus generating a functional hybrid material with low aquatic toxicity and great potential to be applied in environmental nanotechnologies such as the removal of heavy metal ions from water. Copyright © 2017 Elsevier B.V. All rights reserved.

Uptake of N-nitrosodimethylamine (NDMA) from water by phreatophytes in the absence and presence of perchlorate as a co-contaminant.

PubMed

Yifru, Dawit D; Nzengung, Valentine A

2006-12-01

The uptake and fate of the emerging contaminants N-nitrosodimethylamine (NDMA) and perchlorate in phreatophytes was studied in a hydroponics system under greenhouse conditions. NDMA is a potent carcinogen, and perchlorate disrupts the functioning ofthe human thyroid gland. The rate of removal of NDMA from solution by rooted cuttings of black willow (Salix nigra) and hybrid poplar (Populus deltoides x nigra, DN34) trees varied seasonally, with faster removal in summer months when transpiration rates were highest. A linear correlation between the volume of water transpired and mass of NDMA removed from the root zone was observed, especially at higher NDMA concentrations. In bioreactors dosed with both NDMA (0.7-1.0 mg L(-1)) and perchlorate (27 mg L(-1)), no competitive uptake of NDMA and perchlorate was observed. While NDMA was primarily removed from solution by plant uptake, perchlorate was predominantly removed by rhizodegradation. In the presence of NDMA, a slower rate of rhizodegradation of perchlorate was observed, but still significantly faster than the rate of NDMA uptake. For experiments conducted with radiolabeled NDMA, 46.4 +/- 1.1% of the total 14C-activity was recovered in the plant tissues and 47.5% was phytovolatilized. The 46.4 +/- 1.1% recovered in the plants was distributed as follows: 18.8 +/- 1.4% in leaves, 15.9 +/- 5.9% in stems, 7.6 +/- 3.2% in branches, and 3.5 +/- 3.3% in roots. The poor extractability of NDMA with methanol-water (1:1 v/v) from stem and leaf tissues suggested that some fraction of NDMA was assimilated. The calculated transpiration stream concentration factor (TSCF) of 0.28 +/- 0.06 suggests that NDMA is passively taken up by phreatophytes, and mainly phytovolatilized.

Comparative study of P19 EC stem cell differentiation in between conventional hanging drop and the zebrafish chorion as a bio-derived material.

PubMed

Dae Seok Na; Lee, Hwang; Sun Uk Kim; Chang Nam Hwang; Sang Ho Lee; Ji Yoon Kang; Jai Kyeong Kim; James Jungho Pak

2008-07-01

Various materials including glass and polymers have been widely used for stem cell culture due to their biocompatibility. However, the roles of these materials are fundamentally limited because they cannot realize or imitate the complex biological functions of living tissues, except in very simple cases. Here, the development of a bio-derived material suitable for stem cell culture and improvement of differentiation efficiency to specific cell lineages with no stimulating agents by using a chorion obtained from a fertilized zebrafish egg through the removal of the yolk and embryonic cell mass from the egg is reported. Mouse P19 EC stem cells introduced into the empty chorion form a uniform embryoid body (EB) without addition of any inducing agent. It is demonstrated that the zebrafish chorion with nanopores improves efficiencies greatly in the EB formation, cell proliferation, and lineage-specific differentiations compared to those of the conventional hanging drop culture method.

Metastable Pluripotent States in NOD Mouse Derived ES Cells

PubMed Central

Hanna, Jacob; Markoulaki, Styliani; Mitalipova, Maisam; Cheng, Albert W.; Cassady, John P.; Staerk, Judith; Carey, Bryce W.; Lengner, Christopher J.; Foreman, Ruth; Love, Jennifer; Gao, Qing; Kim, Jongpil; Jaenisch, Rudolf

2009-01-01

Embryonic stem (ES) cells are isolated from the inner cell mass (ICM) of blastocysts, whereas epiblast stem cells (EpiSCs) are derived from the post-implantation epiblast and display a restricted developmental potential. Here we characterize pluripotent states in the non-obese diabetic (NOD) mouse strain, which prior to this study was considered “non-permissive” for ES cell derivation. We find that NOD stem cells can be stabilized by providing constitutive expression of Klf4 or c-Myc or small molecules that can replace these factors during in vitro reprogramming. The NOD ES and iPS cells appear “metastable”, as they acquire an alternative EpiSC-like identity after removal of the exogenous factors, while their reintroduction converts the cells back to ICM-like pluripotency. Our findings suggest that stem cells from different genetic backgrounds can assume distinct states of pluripotency in vitro, the stability of which is regulated by endogenous genetic determinants and can be modified by exogenous factors. PMID:19427283

Development of reversible vas deferens occlusive device: IV. Rigid prosthetic devices.

PubMed

Drueschke, E E; Zaneveld, L J; Burns, M; Rodzen, R; Wingfield, J R; Maness, J H

1975-01-01

Different types of rigid, reversible, vas deferens occlusive devices were developed and evaluated in 14 unilaterally vasectomized dogs. All prosthetic devices had molded silicone rubber bodies, and rigid inflow and outflow tubes. Various techniques for the removal of the vas luminal epithelium, and for the preparation of porous ceramic and etched stainless steel surfaces to encourage tissue ingrowth into the prosthetic device end tubues were attempted. The devices differed in their methods of achieving occlusion. One device used a "rotary stem valve" which had a C-section rotating mechanism; the others used the "shuttle stem valve" which possessed an occlusive element that moved transverse to the axis of flow in the device, thus occluding the device when the stem was depressed. The rotarystem valve was implanted by means of a longitudinal incision. The remaining 13 shuttle stem devices were placed in the vas using either a longitudinal or a transverse implantation. Inno case was sperm transport through the prosthetic devices obtained for more than a few ejaculations.

Distinct mechanisms underlie oral vs aboral regeneration in the cnidarian Hydractinia echinata.

PubMed

Bradshaw, Brian; Thompson, Kerry; Frank, Uri

2015-04-17

Cnidarians possess remarkable powers of regeneration, but the cellular and molecular mechanisms underlying this capability are unclear. Studying the hydrozoan Hydractinia echinata we show that a burst of stem cell proliferation occurs following decapitation, forming a blastema at the oral pole within 24 hr. This process is necessary for head regeneration. Knocking down Piwi1, Vasa, Pl10 or Ncol1 expressed by blastema cells inhibited regeneration but not blastema formation. EdU pulse-chase experiments and in vivo tracking of individual transgenic Piwi1(+) stem cells showed that the cellular source for blastema formation is migration of stem cells from a remote area. Surprisingly, no blastema developed at the aboral pole after stolon removal. Instead, polyps transformed into stolons and then budded polyps. Hence, distinct mechanisms act to regenerate different body parts in Hydractinia. This model, where stem cell behavior can be monitored in vivo at single cell resolution, offers new insights for regenerative biology.

Distribution of spawning activity by anadromous fishes in an atlantic slope drainage after removal of a low-head dam

USGS Publications Warehouse

Burdick, S.M.; Hightower, J.E.

2006-01-01

In 1998, the Quaker Neck Dam was removed from the Neuse River near Goldsboro, North Carolina, restoring access to more than 120 km of potential main-stem spawning habitat and 1,488 km of potential tributary spawning habitat to anadromous fishes. We used plankton sampling and standardized electrofishing to examine the extent to which anadromous fishes utilized this restored spawning habitat in 2003 and 2004. Evidence of spawning activity was detected upstream of the former dam site for three anadromous species: American shad Alosa sapidissima, hickory shad A. mediocris, and striped bass Morone saxatilis. The percentages of eggs and larvae collected in the restored upstream habitat were greater in 2003, when spring flows were high, than in 2004. River reaches where spawning occurred were estimated from egg stage and water velocity data. Spawning of American shad and striped bass occurred primarily in main-stem river reaches that were further upstream during the year of higher spring flows. Hickory shad generally spawned in downstream reaches and in tributaries above and below the former dam site. These results demonstrate that anadromous fishes will take advantage of upper basin spawning habitat restored through dam removal as long as instream flows are adequate to facilitate upstream migration.

Clinical grade adult stem cell banking

PubMed Central

Thirumala, Sreedhar; Goebel, W Scott

2009-01-01

There has been a great deal of scientific interest recently generated by the potential therapeutic applications of adult stem cells in human care but there are several challenges regarding quality and safety in clinical applications and a number of these challenges relate to the processing and banking of these cells ex-vivo. As the number of clinical trials and the variety of adult cells used in regenerative therapy increases, safety remains a primary concern. This has inspired many nations to formulate guidelines and standards for the quality of stem cell collection, processing, testing, banking, packaging and distribution. Clinically applicable cryopreservation and banking of adult stem cells offers unique opportunities to advance the potential uses and widespread implementation of these cells in clinical applications. Most current cryopreservation protocols include animal serum proteins and potentially toxic cryoprotectant additives (CPAs) that prevent direct use of these cells in human therapeutic applications. Long term cryopreservation of adult stem cells under good manufacturing conditions using animal product free solutions is critical to the widespread clinical implementation of ex-vivo adult stem cell therapies. Furthermore, to avoid any potential cryoprotectant related complications, reduced CPA concentrations and efficient post-thaw washing to remove CPA are also desirable. The present review focuses on the current strategies and important aspects of adult stem cell banking for clinical applications. These include current good manufacturing practices (cGMPs), animal protein free freezing solutions, cryoprotectants, freezing & thawing protocols, viability assays, packaging and distribution. The importance and benefits of banking clinical grade adult stem cells are also discussed. PMID:20046678

The transplantation of neural stem cells and predictive factors in hematopoietic recovery in irradiated mice.

PubMed

Filip, S; Mokrý, J; Karbanová, J; Vávrová, J; Vokurková, J; Bláha, M; English, D

2005-04-01

A number of surprising observations have shown that stem cells, in suitable conditions, have the ability to produce a whole spectrum of cell types, regardless, whether these tissues are derived from the same germ layer or not. This phenomenon is called stem cell plasticity, which means that tissue-specific stem cells are mutually interchangeable. In our experiments, as a model, we used neural stem cells (NSCs) harvested from fetal (E14-15) neocortex and beta-galactosidase positive. In the first experiment we found that on days 12 and 30 after sub-lethal irradiation (LD 8.5 Gy) and (beta-galactosidase(+)) NSCs transplantation all mice survived, just as the group with bone marrow transplantation. Moreover, the bone marrow of mice transplanted NSCs contained the number of CFU-GM colonies with beta-galactosidase(+) cells which was as much as 50% higher. These differences were statistically significant, p<0.001. In the second experiment, we studied kinetics of (beta-galactosidase(+)) NSCs after their transplantation to sub-lethally irradiated mice. Histochemistry of tissues was performed on days 12 and 30 post-transplantation, and beta-galactosidase(+) cells were detected with the help of histochemical examination of removed tissues (lung, liver, spleen, thymus, and skeletal muscle). In tissues removed on day 12 post-transplantation, we found a significantly higher number of beta-galactosidase(+) cells in the spleen and thymus on day 30. While we presumed the presence beta-galactosidase(+) cells in the spleen, as spleen and reticuloendothelial system represent an important retaining system for different cell types, the presence of beta-galactosidase(+) cells in the thymus was rather surprising but very interesting. This indicates a certain mutual and close interconnection of transplanted stem cells and immune system in an adult organism. In the third experiment, we verified the mutual interchange of Sca-1 surface antigen in the bone marrow cells and NSCs before transplantation. Analysis of this antigen showed 24.8% Sca-1 positive cells among the bone marrow cells, while NSCs were Sca-1 negative. Our experiments show that NSCs share hemopoietic identity and may significantly influence the recovery of damaged hematopoiesis but do not have typical superficial markers as HSCs. This result is important for the determination of predictive factors for hemopoiesis recovery, for stem cell plasticity and for their use in the cell therapy.

Cultivating Diversity and Competency in STEM: Challenges and Remedies for Removing Virtual Barriers to Constructing Diverse Higher Education Communities of Success.

PubMed

Whittaker, Joseph A; Montgomery, Beronda L

2012-01-01

The need to increase the number of college graduates in Science, Technology, Engineering, and Mathematics (STEM) disciplines is a national issue. As the demographics of the United States' population grow increasingly more diverse, the recognition that students of color are disproportionately under-represented among those individuals successful at completing STEM degrees requires exigent and sustained intervention. Although a range of efforts and funding have been committed to increasing the success of under-represented minority (URM) students at primarily white, or majority, institutions, widespread progress has been slow. Simultaneously, Historically Black Colleges and Universities and Minority Serving Institutions have demonstrated disproportionate successes in graduating URM students with STEM degrees and those that proceed to completing graduate-level degrees in the sciences. The differential successes of particular institutions with promoting the achievement of diverse individuals in obtaining academic STEM degrees suggest that with committed and strategic leadership, advancements in creating academic communities that promote the success of a diverse range of students in STEM can be achieved in part through assessing and mitigating environmental barriers that impede success at majority institutions. In this paper, we address issues related to the engagement of URM students in majority settings and describe some efforts that have shown success for promoting diversity in STEM and highlight continuing issues and factors associated with cultivating diversity in academic STEM disciplines at majority institutions. Recommended efforts include addressing academic assistance, professional and cultural socialization issues and institutional environmental factors that are associated with success or lack thereof for URMs in STEM.

Genetic instability associated with loop or stem–loop structures within transcription units can be independent of nucleotide excision repair

PubMed Central

Burns, John A; Chowdhury, Moinuddin A; Cartularo, Laura; Berens, Christian; Scicchitano, David A

2018-01-01

Abstract Simple sequence repeats (SSRs) are found throughout the genome, and under some conditions can change in length over time. Germline and somatic expansions of trinucleotide repeats are associated with a series of severely disabling illnesses, including Huntington's disease. The underlying mechanisms that effect SSR expansions and contractions have been experimentally elusive, but models suggesting a role for DNA repair have been proposed, in particular the involvement of transcription-coupled nucleotide excision repair (TCNER) that removes transcription-blocking DNA damage from the transcribed strand of actively expressed genes. If the formation of secondary DNA structures that are associated with SSRs were to block RNA polymerase progression, TCNER could be activated, resulting in the removal of the aberrant structure and a concomitant change in the region's length. To test this, TCNER activity in primary human fibroblasts was assessed on defined DNA substrates containing extrahelical DNA loops that lack discernible internal base pairs or DNA stem–loops that contain base pairs within the stem. The results show that both structures impede transcription elongation, but there is no corresponding evidence that nucleotide excision repair (NER) or TCNER operates to remove them. PMID:29474673

Concise Review: Stem Cells in Osteoimmunology.

PubMed

Fierro, Fernando A; Nolta, Jan A; Adamopoulos, Iannis E

2017-06-01

Bone remodeling is a lifelong process in which mature bone tissue is removed from the skeleton by bone resorption and is replenished by new during ossification or bone formation. The remodeling cycle requires both the differentiation and activation of two cell types with opposing functions; the osteoclast, which orchestrates bone resorption, and the osteoblast, which orchestrates bone formation. The differentiation of these cells from their respective precursors is a process which has been overshadowed by enigma, particularly because the precise osteoclast precursor has not been identified and because the identification of skeletal stem cells, which give rise to osteoblasts, is very recent. Latest advances in the area of stem cell biology have enabled us to gain a better understanding of how these differentiation processes occur in physiological and pathological conditions. In this review we postulate that modulation of stem cells during inflammatory conditions is a necessary prerequisite of bone remodeling and therefore an essential new component to the field of osteoimmunology. In this context, we highlight the role of transcription factor nuclear factor of activated T cells cytoplasmic 1 (NFATc1), because it directly links inflammation with differentiation of osteoclasts and osteoblasts. Stem Cells 2017;35:1461-1467. © 2017 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Synergy of multi-scale toughening and protective mechanisms at hierarchical branch-stem interfaces

NASA Astrophysics Data System (ADS)

Müller, Ulrich; Gindl-Altmutter, Wolfgang; Konnerth, Johannes; Maier, Günther A.; Keckes, Jozef

2015-09-01

Biological materials possess a variety of artful interfaces whose size and properties are adapted to their hierarchical levels and functional requirements. Bone, nacre, and wood exhibit an impressive fracture resistance based mainly on small crystallite size, interface organic adhesives and hierarchical microstructure. Currently, little is known about mechanical concepts in macroscopic biological interfaces like the branch-stem junction with estimated 1014 instances on earth and sizes up to few meters. Here we demonstrate that the crack growth in the upper region of the branch-stem interface of conifer trees proceeds along a narrow predefined region of transversally loaded tracheids, denoted as sacrificial tissue, which fail upon critical bending moments on the branch. The specific arrangement of the tracheids allows disconnecting the overloaded branch from the stem in a controlled way by maintaining the stem integrity. The interface microstructure based on the sharply adjusted cell orientation and cell helical angle secures a zig-zag crack propagation path, mechanical interlock closing after the bending moment is removed, crack gap bridging and self-repairing by resin deposition. The multi-scale synergetic concepts allows for a controllable crack growth between stiff stem and flexible branch, as well as mechanical tree integrity, intact physiological functions and recovery after the cracking.

Stem compression reversibly reduces phloem transport in Pinus sylvestris trees.

PubMed

Henriksson, Nils; Tarvainen, Lasse; Lim, Hyungwoo; Tor-Ngern, Pantana; Palmroth, Sari; Oren, Ram; Marshall, John; Näsholm, Torgny

2015-10-01

Manipulating tree belowground carbon (C) transport enables investigation of the ecological and physiological roles of tree roots and their associated mycorrhizal fungi, as well as a range of other soil organisms and processes. Girdling remains the most reliable method for manipulating this flux and it has been used in numerous studies. However, girdling is destructive and irreversible. Belowground C transport is mediated by phloem tissue, pressurized through the high osmotic potential resulting from its high content of soluble sugars. We speculated that phloem transport may be reversibly blocked through the application of an external pressure on tree stems. Thus, we here introduce a technique based on compression of the phloem, which interrupts belowground flow of assimilates, but allows trees to recover when the external pressure is removed. Metal clamps were wrapped around the stems and tightened to achieve a pressure theoretically sufficient to collapse the phloem tissue, thereby aiming to block transport. The compression's performance was tested in two field experiments: a (13)C canopy labelling study conducted on small Scots pine (Pinus sylvestris L.) trees [2-3 m tall, 3-7 cm diameter at breast height (DBH)] and a larger study involving mature pines (∼15 m tall, 15-25 cm DBH) where stem respiration, phloem and root carbohydrate contents, and soil CO2 efflux were measured. The compression's effectiveness was demonstrated by the successful blockage of (13)C transport. Stem compression doubled stem respiration above treatment, reduced soil CO2 efflux by 34% and reduced phloem sucrose content by 50% compared with control trees. Stem respiration and soil CO2 efflux returned to normal within 3 weeks after pressure release, and (13)C labelling revealed recovery of phloem function the following year. Thus, we show that belowground phloem C transport can be reduced by compression, and we also demonstrate that trees recover after treatment, resuming C transport in the phloem. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

SU-E-I-39: Molecular Image Guided Cancer Stem Cells Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdollahi, H

Purpose: Cancer stem cells resistance to radiation is a problematic issue that has caused a big fail in cancer treatment. Methods: As a primary work, molecular imaging can indicate the main mechanisms of radiation resistance of cancer stem cells. By developing and commissioning new probes and nanomolecules and biomarkers, radiation scientist will able to identify the essential pathways of radiation resistance of cancer stem cells. As the second solution, molecular imaging is a best way to find biological target volume and delineate cancer stem cell tissues. In the other hand, by molecular imaging techniques one can image the treatment responsemore » in tumor and also in normal tissue. In this issue, the response of cancer stem cells to radiation during therapy course can be imaged, also the main mechanisms of radiation resistance and finding the best radiation modifiers (sensitizers) can be achieved by molecular imaging modalities. In adaptive radiotherapy the molecular imaging plays a vital role to have higher tumor control probability by delivering high radiation doses to cancer stem cells in any time of treatment. The outcome of a feasible treatment is dependent to high cancer stem cells response to radiation and removing all of which, so a good imaging modality can show this issue and preventing of tumor recurrence and metastasis. Results: Our results are dependent to use of molecular imaging as a new modality in the clinic. We propose molecular imaging as a new radiobiological technique to solve radiation therapy problems due to cancer stem cells. Conclusion: Molecular imaging guided cancer stem cell diagnosis and therapy is a new approach in the field of cancer treatment. This new radiobiological imaging technique should be developed in all clinics as a feasible tool that is more biological than physical imaging.« less

The Role of stocking in the reestablishment and augmentation of native fish in the Lower Colorado River mainstream (1998-2002)

USGS Publications Warehouse

Mueller, Gordon

2003-01-01

Recovery in the main stem will only be accomplished with a dramatic decrease and possibly a total removal of nonnative species. After ten years and over $6 million in expenditures to remove nonnative fish it appears this philosophy is neither technically nor politically viable. In the meantime, stocking is the only alternative available to insure these species don’t disappear. The only viable option appears the creation and maintenance of small, isolated refuge communities where these species have shown they can produce young.

Evaluation of triple antibiotic paste removal by different irrigation procedures.

PubMed

Berkhoff, Julie A; Chen, Paul B; Teixeira, Fabricio B; Diogenes, Anibal

2014-08-01

Regenerative endodontics aims to re-establish a functional pulp-dentin complex. First, the root canal system is disinfected primarily by irrigants and medicaments. Triple antibiotic paste (TAP), a commonly used intracanal medicament, has been shown to be directly toxic to stem cells at concentrations greater than 0.1 g/mL. Thus, its complete removal is a crucial step in regenerative endodontic procedures. We hypothesized that currently used irrigation techniques do not completely remove TAP from root canal system. TAP was radiolabeled by the incorporation of I(125), and calcium hydroxide (Ultracal; Ultradent, South Jordan, UT) was radiolabeled with Ca(45). The intracanal medicaments were placed into standardized human root segments and incubated for 28 days at 37°C. Then, canals were irrigated with EndoActivator (Dentsply, Tulsa, OK), passive ultrasonic irrigation, EndoVac (SybronEndo, Coppell, TX), or a syringe/Max-i-Probe needle (Dentsply Rinn, Elgin, IL) using a standardized irrigation protocol in a closed system. Radioactivity levels (counts per minute values) were measured for each tooth before and after the irrigation protocols. Furthermore, the canals were sequentially enlarged and dentin samples collected and evaluated for radioactivity. Data were analyzed with analysis of variance and Bonferroni post hoc testing (P < .05). Approximately 88% of the TAP was retained in the root canal system regardless of the irrigation technique used (no difference among groups). Furthermore, approximately 50% of the radiolabeled TAP was present circumferentially up to 350 μm within the dentin. Conversely, up to 98% of the radiolabeled intracanal calcium hydroxide was removed, and most residual medicament was found present in the initial 50 μm of dentin. Current irrigation techniques do not effectively remove TAP from root canal systems, possibly because of its penetration and binding into dentin. However, calcium hydroxide is effectively removed with significant less residual presence. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

The effects of a STEM professional development intervention on elementary teachers

NASA Astrophysics Data System (ADS)

Dailey, Deborah D.

To improve and sustain science teaching and learning in the elementary grades, experts recommended school districts afford time in the day for science instruction, secure the necessary resources for an investigative classroom, and provide teachers with increased professional development opportunities that target content knowledge, pedagogical skills, and confidence in teaching science (e.g. Buczynski & Hansen, 2010; Brand & Moore, 2011; NSB, 2010). In particular, researchers recommended teachers receive quality professional development that is sustained over time and embedded in the real world of the classroom (e.g. Buczynski & Hansen, 2010; Cotabish & Robinson, 2012). The purpose of this dissertation was to examine changes in elementary teachers' science teaching perceptions, concerns, and science process skills during and after participation in a STEM-focused professional development intervention involving embedded support using peer coaching. The positive effects of sustained, embedded professional development programs on science instruction have been documented by multiple research studies (e.g. Buczynski & Hansen, 2010; Cotabish, Dailey, Hughes, & Robinson, 2011; Duran & Duran, 2005; Levitt, 2011); however, few studies have investigated the effects after removal of the professional development support (Johnson, Kahle, & Fargo, 2007; Shymansky, Yore, & Anderson, 2004). By examining the changes across three years (including one year after the conclusion of the professional development intervention), the researcher in the present study considered the dosage of intervention needed to bring about and preserve significant changes in the participant teachers. To measure the impact of the intervention on teachers, the researcher used quantitative data supported by qualitative interviews. Results indicated that changes in science teaching perceptions were realized after one year or 60 hours of intervention; however, it took two years or 120 hours of intervention to see significant changes in teachers' science process skills. Of particular significance, the changes in teachers' science teaching perceptions, concerns, and science process skills held constant one year after removal of the professional development support.

Investigating Preservice STEM Teacher Conceptions of STEM Education

ERIC Educational Resources Information Center

Radloff, Jeff; Guzey, Selcen

2016-01-01

Surrounding the national emphasis on improving STEM education, effective STEM educators are required. Connected, yet often overlooked, is the need for effective preservice STEM teaching instruction for incoming educators. At a basic level, preservice STEM teacher education should include STEM content, pedagogy, and conceptualization. However, the…

7 CFR 52.1844 - Definition of terms.

Code of Federal Regulations, 2014 CFR

2014-01-01

... of the branch or main stem. (c) Seeds refers to whole, fully developed seeds which have not been removed during the processing of seeded raisins with seeds. (d) Damaged raisins means raisins affected by... appearance, edibility, keeping quality, or shipping quality of the raisins. In seeded Raisins with Seeds...

7 CFR 52.1844 - Definition of terms.

Code of Federal Regulations, 2013 CFR

2013-01-01

... of the branch or main stem. (c) Seeds refers to whole, fully developed seeds which have not been removed during the processing of seeded raisins with seeds. (d) Damaged raisins means raisins affected by... appearance, edibility, keeping quality, or shipping quality of the raisins. In seeded Raisins with Seeds...

Hypoxic stress induces, but cannot sustain trophoblast stem cell differentiation to labyrinthine placenta due to mitochondrial insufficiency

PubMed Central

Xie, Yufen; Zhou, Sichang; Jiang, Zhongliang; Dai, Jing; Puscheck, Elizabeth E; Lee, Icksoo; Parker, Graham; Hüttemann, Maik; Rappolee, Daniel A

2014-01-01

Dysfunctional stem cell differentiation into placental lineages is associated with gestational diseases. Of the differentiated lineages available to trophoblast stem cells (TSC), elevated O2 and mitochondrial function are necessary to placental lineages at the maternal-placental surface and important in the etiology of preeclampsia. TSC lineage imbalance leads to embryonic failure during uterine implantation. Stress at implantation exacerbates stem cell depletion by decreasing proliferation and increasing differentiation. Implantation site O2 is normally ~2%. In culture, exposure to 2% O2 and fibroblast growth factor (FGF)4 enabled highest mouse TSC multipotency and proliferation. In contrast, hypoxic stress (0.5% O2) initiated the most TSC differentiation after 24 hr despite FGF4. However, hypoxic stress supported differentiation poorly after 4–7 days, despite FGF4 removal. At all tested O2 levels, FGF4 maintained Warburg metabolism; mitochondrial inactivity and aerobic glycolysis. However, hypoxic stress suppressed mitochondrial membrane potential, maintained low mitochondrial cytochrome c oxidase (oxidative phosphorylation/OxPhos), and high pyruvate kinase M2 (glycolysis) despite FGF4 removal. Inhibiting OxPhos inhibited differentiation at the differentiation optimum at 20% O2. Moreover, adding differentiation-inducing hyperosmolar stress failed to induce differentiation during hypoxia. Thus, differentiation depended on OxPhos at 20% O2; hypoxic and hyperosmolar stresses did not induce differentiation at 0.5% O2. Hypoxia-limited differentiation and mitochondrial inhibition and activation suggest that differentiation into two lineages of the labyrinthine placenta requires O2>0.5–2% and mitochondrial function. Stress-activated protein kinase increases an early lineage and suppresses later lineages in proportion to the deviation from optimal O2 for multipotency, thus it is the first enzyme reported to prioritize differentiation. PMID:25239494

Murine pluripotent stem cells derived scaffold-free cartilage grafts from a micro-cavitary hydrogel platform.

PubMed

He, Pengfei; Fu, Jiayin; Wang, Dong-An

2016-04-15

By means of appropriate cell type and scaffold, tissue-engineering approaches aim to construct grafts for cartilage repair. Pluripotent stem cells especially induced pluripotent stem cells (iPSCs) are of promising cell candidates due to the pluripotent plasticity and abundant cell source. We explored three dimensional (3D) culture and chondrogenesis of murine iPSCs (miPSCs) on an alginate-based micro-cavity hydrogel (MCG) platform in pursuit of fabricating synthetic-scaffold-free cartilage grafts. Murine embryonic stem cells (mESCs) were employed in parallel as the control. Chondrogenesis was fulfilled using a consecutive protocol via mesoderm differentiation followed by chondrogenic differentiation; subsequently, miPSC and mESC-seeded constructs were further respectively cultured in chondrocyte culture (CC) medium. Alginate phase in the constructs was then removed to generate a graft only comprised of induced chondrocytic cells and cartilaginous extracellular matrix (ECMs). We found that from the mESC-seeded constructs, formation of intact grafts could be achieved in greater sizes with relatively fewer chondrocytic cells and abundant ECMs; from miPSC-seeded constructs, relatively smaller sized cartilaginous grafts could be formed by cells with chondrocytic phenotype wrapped by abundant and better assembled collagen type II. This study demonstrated successful creation of pluripotent stem cells-derived cartilage/chondroid graft from a 3D MCG interim platform. By the support of materials and methodologies established from this study, particularly given the autologous availability of iPSCs, engineered autologous cartilage engraftment may be potentially fulfilled without relying on the limited and invasive autologous chondrocytes acquisition. In this study, we explored chondrogenic differentiation of pluripotent stem cells on a 3D micro-cavitary hydrogel interim platform and creation of pluripotent stem cells-derived cartilage/chondroid graft via a consecutive procedure. Our results demonstrated chondrogenic differentiation could be realized on the platform via mesoderm differentiation. The mESCs/miPSCs derived chondrocytic cells were further cultured to finally generate a pluripotent stem cells-derived scaffold-free construct based on the micro-cavitary hydrogel platform, in which alginate hydrogel could be removed finally. Our results showed that miPSC-derived graft could be formed by cells with chondrocytic phenotype wrapped by abundant and assembled collagen type II. To our knowledge, this study is the first study that initials from pluripotent stem cell seeding on 3D scaffold environment and ends with a scaffold-free chondrogenic micro-tissue. By the support of materials and methodologies established from this study, engineered autologous iPSC-derived cartilage engraftment may be potentially developed instead of autologous chondrocytes grafts that have limited source. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

DMRT1 Is Required for Mouse Spermatogonial Stem Cell Maintenance and Replenishment.

PubMed

Zhang, Teng; Oatley, Jon; Bardwell, Vivian J; Zarkower, David

2016-09-01

Male mammals produce sperm for most of postnatal life and therefore require a robust germ line stem cell system, with precise balance between self-renewal and differentiation. Prior work established doublesex- and mab-3-related transcription factor 1 (Dmrt1) as a conserved transcriptional regulator of male sexual differentiation. Here we investigate the role of Dmrt1 in mouse spermatogonial stem cell (SSC) homeostasis. We find that Dmrt1 maintains SSCs during steady state spermatogenesis, where it regulates expression of Plzf, another transcription factor required for SSC maintenance. We also find that Dmrt1 is required for recovery of spermatogenesis after germ cell depletion. Committed progenitor cells expressing Ngn3 normally do not contribute to SSCs marked by the Id4-Gfp transgene, but do so when spermatogonia are chemically depleted using busulfan. Removal of Dmrt1 from Ngn3-positive germ cells blocks the replenishment of Id4-GFP-positive SSCs and recovery of spermatogenesis after busulfan treatment. Our data therefore reveal that Dmrt1 supports SSC maintenance in two ways: allowing SSCs to remain in the stem cell pool under normal conditions; and enabling progenitor cells to help restore the stem cell pool after germ cell depletion.

Ontogenesis and functions of saxophone stem in Acrocomia aculeata (Arecaceae)

PubMed Central

e Souza, Joyce Nascimento; Ribeiro, Leonardo Monteiro; Mercadante-Simões, Maria Olívia

2017-01-01

Background and Aims The underground saxophone stem systems produced by seedlings of certain palm species show peculiar growth patterns and distinctive morphologies, although little information is available concerning their development and function. We studied the ontogenesis of the saxophone stem in Acrocomia aculeata, an important neotropical oleaginous palm, and sought to experimentally define its function. Methods Morpho-anatomical evaluations were performed during 240 d on seedlings using traditional methodologies. The tuberous region of the structure was submitted to histochemical tests and evaluated by transmission electron microscopy. The aerial portions of 130 1- to 3-year-old greenhouse plants were removed and their continuous growth capacity was evaluated after 30 d. Severed saxophone stems were also stored at room temperature (average 25 °C) for up to 90 d and then cultured for 60 d to evaluate root and shoot emission. Key Results The development of the saxophone stem is distinct from other underground systems previously described, and involves three processes: growth and curvature of the cotyledonary petiole, expansion and curvature of the hypocotyl, and expansion of the plumule internodes. The tuberous region stores water and starch, as well as lesser amounts of mucilage and oil. Growth of the aerial portion occurred in 84 % of the separated saxophone stems and in 53 % of the stems held in storage. Conclusions The saxophone stem represents an important adaptation of A. aculeata to anthropogenically impacted and/or dry environments by promoting the burial of both the shoot meristem and storage reserves, which allows the continuous growth of aerial organs. PMID:28028018

Histone h1 depletion impairs embryonic stem cell differentiation.

PubMed

Zhang, Yunzhe; Cooke, Marissa; Panjwani, Shiraj; Cao, Kaixiang; Krauth, Beth; Ho, Po-Yi; Medrzycki, Magdalena; Berhe, Dawit T; Pan, Chenyi; McDevitt, Todd C; Fan, Yuhong

2012-01-01

Pluripotent embryonic stem cells (ESCs) are known to possess a relatively open chromatin structure; yet, despite efforts to characterize the chromatin signatures of ESCs, the role of chromatin compaction in stem cell fate and function remains elusive. Linker histone H1 is important for higher-order chromatin folding and is essential for mammalian embryogenesis. To investigate the role of H1 and chromatin compaction in stem cell pluripotency and differentiation, we examine the differentiation of embryonic stem cells that are depleted of multiple H1 subtypes. H1c/H1d/H1e triple null ESCs are more resistant to spontaneous differentiation in adherent monolayer culture upon removal of leukemia inhibitory factor. Similarly, the majority of the triple-H1 null embryoid bodies (EBs) lack morphological structures representing the three germ layers and retain gene expression signatures characteristic of undifferentiated ESCs. Furthermore, upon neural differentiation of EBs, triple-H1 null cell cultures are deficient in neurite outgrowth and lack efficient activation of neural markers. Finally, we discover that triple-H1 null embryos and EBs fail to fully repress the expression of the pluripotency genes in comparison with wild-type controls and that H1 depletion impairs DNA methylation and changes of histone marks at promoter regions necessary for efficiently silencing pluripotency gene Oct4 during stem cell differentiation and embryogenesis. In summary, we demonstrate that H1 plays a critical role in pluripotent stem cell differentiation, and our results suggest that H1 and chromatin compaction may mediate pluripotent stem cell differentiation through epigenetic repression of the pluripotency genes.

Efficacy of periodontal stem cell transplantation in the treatment of advanced periodontitis.

PubMed

Park, Joo-Young; Jeon, Soung Hoo; Choung, Pill-Hoon

2011-01-01

Periodontitis is the most common cause for tooth loss in adults and advanced types affect 10-15% of adults worldwide. The attempts to save tooth and regenerate the periodontal apparatus including cementum, periodontal ligament, and alveolar bone reach to the dental tissue-derived stem cell therapy. Although there have been several periodontitis models suggested, the apical involvement of tooth root is especially challenging to be regenerated and dental stem cell therapy for the state has never been investigated. Three kinds of dental tissue-derived adult stem cells (aDSCs) were obtained from the extracted immature molars of beagle dogs (n = 8), and ex vivo expanded periodontal ligament stem cells (PDLSCs), dental pulp stem cells (DPSCs), and periapical follicular stem cells (PAFSCs) were transplanted into the apical involvement defect. As for the lack of cementum-specific markers, anti-human cementum protein 1 (rhCEMP1) antibody was fabricated and the aDSCs and the regenerated tissues were immunostained with anti-CEMP1 antibody. Autologous PDLSCs showed the best regenerating capacity of periodontal ligament, alveolar bone, and cementum as well as peripheral nerve and blood vessel, which were evaluated by conventional and immune histology, 3D micro-CT, and clinical index. The rhCEMP1 was expressed strongest in PDLSCs and in the regenerated periodontal ligament space. We suggest here the PDLSCs as the most favorable candidate for the clinical application among the three dental stem cells and can be used for treatment of advanced periodontitis where tooth removal was indicated in the clinical cases. © 2011 Cognizant Comm. Corp.

Effects of glucose, lactate and basic FGF as limiting factors on the expansion of human induced pluripotent stem cells.

PubMed

Horiguchi, Ikki; Urabe, Yusuke; Kimura, Keiichi; Sakai, Yasuyuki

2018-01-01

Pluripotent stem cells (PSCs) are one of the promising cell sources for tissue engineering and drug screening. However, mass production of induced pluripotent stem cells (iPSCs) is still developing. Especially, a huge amount of culture medium usage causes expensive cost in the mass production process. In this report, we reduced culture medium usage by extending interval of changing culture medium. In parallel, we also increased glucose concentration and supplied heparan sulfate to avoid depletion of glucose and bFGF, respectively. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analyses showed that reducing medium change frequency increased differentiation marker expressions but high glucose concentration downregulated these expressions. In contrast, heparan sulfate did not prevent differentiation marker expressions. According to analyses of growth rate, cell growth with extended medium change interval was decreased in later stage of log growth phase despite the existence of high glucose concentration and heparan sulfate. This result and culturing iPSCs with lactate showed that the accumulation of excreted lactate decreased the growth rate regardless of pH control. Conclusively, these experiments show that adding glucose and removing lactate are important to expand iPSCs with reduced culture medium usage. This knowledge should be useful to design economical iPSC mass production and differentiation system. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Sutureless amniotic membrane transplantation for partial limbal stem cell deficiency.

PubMed

Kheirkhah, Ahmad; Casas, Victoria; Raju, Vadrevu K; Tseng, Scheffer C G

2008-05-01

To evaluate the results of sutureless amniotic membrane (AM) transplantation using fibrin glue for reconstructing corneal surfaces with partial limbal stem cell deficiency (LSCD). Retrospective noncomparative interventional case series. Eleven eyes of nine patients that had LSCD with 120 degrees to almost 360 degrees of limbal involvement underwent superficial keratectomy to remove the conjunctivalized pannus followed by AM transplantation using fibrin glue. Additional sutureless AM patch (ProKera; Bio-Tissue, Inc, Miami, Florida, USA) was used in seven patients, and mitomycin C was applied on the cornea in four eyes and during fornix reconstruction in seven eyes. The surgery was repeated in three eyes for residual pannus. During a mean follow-up of 14.2 +/- 7.7 months (range, six to 26 months), all eyes maintained a smooth and stable corneal epithelial surface without recurrent erosion or persistent epithelial defect, and showed less stromal cloudiness and vascularization. Best-corrected visual acuity improved in nine eyes (81.8%). Corneal epithelialization proceeded by epithelial growth over AM (n = 4), accompanied by dissolution of AM (n = 4) or a combination of both (n = 3). No complication was noted regarding initial or repeated uses of fibrin glue. AM transplantation using fibrin glue appears to be a safe and effective method of restoring a stable corneal epithelium for cases with partial LSCD. This approach avoids the need of transplanting limbal epithelial stem cells.

Residual stress prediction in a powder bed fusion manufactured Ti6Al4V hip stem

NASA Astrophysics Data System (ADS)

Barrett, Richard A.; Etienne, Titouan; Duddy, Cormac; Harrison, Noel M.

2017-10-01

Powder bed fusion (PBF) is a category of additive manufacturing (AM) that is particularly suitable for the production of 3D metallic components. In PBF, only material in the current build layer is at the required melt temperature, with the previously melted and solidified layers reducing in temperature, thus generating a significant thermal gradient within the metallic component, particularly for laser based PBF components. The internal thermal stresses are subsequently relieved in a post-processing heat-treatment step. Failure to adequately remove these stresses can result in cracking and component failure. A prototype hip stem was manufactured from Ti6Al4V via laser PBF but was found to have fractured during over-seas shipping. This study examines the evolution of thermal stresses during the laser PBF manufacturing and heat treatment processes of the hip stem in a 2D finite element analysis (FEA) and compares it to an electron beam PBF process. A custom written script for the automatic conversion of a gross geometry finite element model into a thin layer- by-layer finite element model was developed. The build process, heat treatment (for laser PBF) and the subsequent cooling were simulated at the component level. The results demonstrate the effectiveness of the heat treatment in reducing PBF induced thermal stresses, and the concentration of stresses in the region that fractured.

Indoleamine 2,3-Dioxygenase Is Dispensable for The Immunomodulatory Function of Stem Cells from Human Exfoliated Deciduous Teeth.

PubMed

Alipour, Razieh; Masoumi Karimi, Masoumeh; Hashemi-Beni, Batool; Adib, Minoo; Sereshki, Nasrin; Sadeghi, Farzaneh

2017-01-01

In this study, we sought to better understand the immunoregulatory function of stem cells derived from human exfoliated deciduous teeth (SHED). We studied the role of the interferon gamma (IFN-γ)-indoleamine 2,3-dioxygenase (IDO)-axis in immunoregulation of SHED compared to bone marrow derived mesenchymal stem cells (BMMSCs) under the same conditions. In this cross-sectional study, recently isolated human T cells were stimulated either by mitogen or inactivated allogeneic peripheral blood mononuclear cells (PBMCs). These T cells were subsequently co-cultured with, either SHED or BMMSCs in the presence or absence of 1-methyl-tryptophan (1-MT) or neutralizing anti- human-IFN-γ antibodies. In all co-cultures we evaluated lymphocyte activation as well as IDO activity. SHED, similar to conventional BMMSCs, had anti-proliferative effects on stimulated T cells and reduced their cytokine production. This property of SHED and BMMSCs was changed by IFN-γ neutralization. We detected IDO in the immunosuppressive supernatant of all co-cultures. Removal of IDO decreased the immunosuppression of BMMSCs. SHED, like BMMSCs, produced the IDO enzyme. Although IFN-γ is one of inducer of IDO production in SHED, these cells were not affected by IFN-γ in the same manner as BMMSCs. Unlike BMMSCs, the IDO enzyme did not contribute to their immunosuppression and might have other cell-type specific roles.

Peripheral Motor and Sensory Nerve Conduction following Transplantation of Undifferentiated Autologous Adipose Tissue-Derived Stem Cells in a Biodegradable U.S. Food and Drug Administration-Approved Nerve Conduit.

PubMed

Klein, Silvan M; Vykoukal, Jody; Li, De-Pei; Pan, Hui-Lin; Zeitler, Katharina; Alt, Eckhard; Geis, Sebastian; Felthaus, Oliver; Prantl, Lukas

2016-07-01

Conduits preseeded with either Schwann cells or stem cells differentiated into Schwann cells demonstrated promising results for the outcome of nerve regeneration in nerve defects. The concept of this trial combines nerve repair by means of a commercially available nerve guidance conduit and preseeding with autologous, undifferentiated, adipose tissue-derived stem cells. Adipose tissue-derived stem cells were harvested from rats and subsequently seeded onto a U.S. Food and Drug Administration-approved type I collagen conduit. Sciatic nerve gaps 10 mm in length were created, and nerve repair was performed by the transplantation of either conduits preseeded with autologous adipose tissue-derived stem cells or acellular (control group) conduits. After 6 months, the motor and sensory nerve conduction velocity were assessed. Nerves were removed and examined by hematoxylin and eosin, van Gieson, and immunohistochemistry (S100 protein) staining for the quality of axonal regeneration. Nerve gaps treated with adipose tissue-derived stem cells showed superior nerve regeneration, reflected by higher motor and sensory nerve conduction velocity values. The motor and sensory nerve conduction velocity were significantly greater in nerves treated with conduits preseeded with adipose tissue-derived stem cells than in nerves treated with conduits alone (p < 0.05). Increased S100 immunoreactivity was detected for the adipose tissue-derived stem cell group. In this group, axon arrangement inside the conduits was more organized. Transplantation of adipose tissue-derived stem cells significantly improves motor and sensory nerve conduction velocity in peripheral nerve gaps. Preseeded conduits showed a more organized axon arrangement inside the conduit in comparison with nerve conduits alone. The approach used here could readily be translated into a clinical therapy. Therapeutic, V.

Recovery of CD45(-)/Lin(-)/SSEA-4(+) very small embryonic-like stem cells by cord blood bank standard operating procedures.

PubMed

Chang, Yu-Jen; Tien, Kuei-Erh; Wen, Cheng-Hao; Hsieh, Tzu-Bou; Hwang, Shiaw-Min

2014-04-01

Very small embryonic-like (VSEL) stem cells are a rare cell population present in bone marrow, cord blood and other tissues that displays a distinct small cell size and the ability to give rise to cells of the three germ layers. VSEL stem cells were reported to be discarded in the red blood cell fraction by Ficoll-Paque density gradient centrifugation during the processing of bone marrow and cord blood specimens. However, most cord blood banks do not include density gradient centrifugation in their procedures while red blood cells are removed by Hespan sedimentation following the Cord Blood Transplantation Study cord blood bank standard operating procedures (COBLT SOP). To clarify the retention of VSEL stem cells, we investigated the recovery of VSEL stem cells following COBLT SOP guidelines. The recovery of CD45(-)/Lin(-)/SSEA-4(+) VSEL stem cells of umbilical cord blood was examined by flow cytometry before and after COBLT SOP processing, and relative expression of pluripotent genes was analyzed by quantitative polymerase chain reaction. CD45(-)/Lin(-)/SSEA-4(+) VSEL stem cells were mostly recovered in the final products following COBLT SOP guidelines. The expression of pluripotent genes could be maintained at >80% in products after hetastarch (Hespan; B. Braun Medical Inc., Irvine, CA, USA) processing. The rare sub-population of CD45(-)/Lin(-)/SSEA-4(+) VSEL stem cells survived after Hespan sedimentation. This finding suggests that umbilical cord blood units cryopreserved by COBLT SOP in cord blood banks should retain most VSEL stem cells present in the un-processed specimens. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Brook trout movement in response to temperature, flow, and thermal refugia within a complex Appalachian riverscape

USGS Publications Warehouse

Petty, J. Todd; Hansbarger, Jeff L.; Huntsman, Brock M.; Mazik, Patricia M.

2012-01-01

We quantified movements of brook trout Salvelinus fontinalis and brown trout Salmo trutta in a complex riverscape characterized by a large, open-canopy main stem and a small, closed-canopy tributary in eastern West Virginia, USA. Our objectives were to quantify the overall rate of trout movement and relate movement behaviors to variation in streamflow, water temperature, and access to coldwater refugia. The study area experienced extremely high seasonal, yearly, and among-stream variability in water temperature and flow. The relative mobility of brook trout within the upper Shavers Fork watershed varied significantly depending on whether individuals resided within the larger main stem or the smaller tributary. The movement rate of trout inhabiting the main stem during summer months (50 m/d) was an order of magnitude higher than that of tributary fish (2 m/d). Movement rates of main-stem-resident brook trout during summer were correlated with the maximum water temperature experienced by the fish and with the fish's initial distance from a known coldwater source. For main-stem trout, use of microhabitats closer to cover was higher during extremely warm periods than during cooler periods; use of microhabitats closer to cover during warm periods was also greater for main-stem trout than for tributary inhabitants. Main-stem-resident trout were never observed in water exceeding 19.5°C. Our study provides some of the first data on brook trout movements in a large Appalachian river system and underscores the importance of managing trout fisheries in a riverscape context. Brook trout conservation in this region will depend on restoration and protection of coldwater refugia in larger river main stems as well as removal of barriers to trout movement near tributary and main-stem confluences.

Potential Use of Human Periapical Cyst-Mesenchymal Stem Cells (hPCy-MSCs) as a Novel Stem Cell Source for Regenerative Medicine Applications

PubMed Central

Tatullo, Marco; Codispoti, Bruna; Pacifici, Andrea; Palmieri, Francesca; Marrelli, Massimo; Pacifici, Luciano; Paduano, Francesco

2017-01-01

Mesenchymal stem cells (MSCs) are attracting growing interest by the scientific community due to their huge regenerative potential. Thus, the plasticity of MSCs strongly suggests the utilization of these cells for regenerative medicine applications. The main issue about the clinical use of MSCs is related to the complex way to obtain them from healthy tissues; this topic has encouraged scientists to search for novel and more advantageous sources of these cells in easily accessible tissues. The oral cavity hosts several cell populations expressing mesenchymal stem cell like-features, furthermore, the access to oral and dental tissues is simple and isolation of cells is very efficient. Thus, oral-derived stem cells are highly attractive for clinical purposes. In this context, human periapical cyst mesenchymal stem cells (hPCy-MSCs) exhibit characteristics similar to other dental-derived MSCs, including their extensive proliferative potential, cell surface marker profile and the ability to differentiate into various cell types such as osteoblasts, adipocytes and neurons. Importantly, hPCy-MSCs are easily collected from the surgically removed periapical cysts; this reusing of biological waste guarantees a smart source of stem cells without any impact on the surrounding healthy tissues. In this review, we report the most interesting research topics related to hPCy-MSCs with a newsworthy discussion about the future insights. This newly discovered cell population exhibits interesting and valuable potentialities that could be of high impact in the future regenerative medicine applications. PMID:29259970

Potential Use of Human Periapical Cyst-Mesenchymal Stem Cells (hPCy-MSCs) as a Novel Stem Cell Source for Regenerative Medicine Applications.

PubMed

Tatullo, Marco; Codispoti, Bruna; Pacifici, Andrea; Palmieri, Francesca; Marrelli, Massimo; Pacifici, Luciano; Paduano, Francesco

2017-01-01

Mesenchymal stem cells (MSCs) are attracting growing interest by the scientific community due to their huge regenerative potential. Thus, the plasticity of MSCs strongly suggests the utilization of these cells for regenerative medicine applications. The main issue about the clinical use of MSCs is related to the complex way to obtain them from healthy tissues; this topic has encouraged scientists to search for novel and more advantageous sources of these cells in easily accessible tissues. The oral cavity hosts several cell populations expressing mesenchymal stem cell like-features, furthermore, the access to oral and dental tissues is simple and isolation of cells is very efficient. Thus, oral-derived stem cells are highly attractive for clinical purposes. In this context, human periapical cyst mesenchymal stem cells (hPCy-MSCs) exhibit characteristics similar to other dental-derived MSCs, including their extensive proliferative potential, cell surface marker profile and the ability to differentiate into various cell types such as osteoblasts, adipocytes and neurons. Importantly, hPCy-MSCs are easily collected from the surgically removed periapical cysts; this reusing of biological waste guarantees a smart source of stem cells without any impact on the surrounding healthy tissues. In this review, we report the most interesting research topics related to hPCy-MSCs with a newsworthy discussion about the future insights. This newly discovered cell population exhibits interesting and valuable potentialities that could be of high impact in the future regenerative medicine applications.

Effect of temperature on phytoextraction of hexavalent and trivalent chromium by hybrid willows.

PubMed

Yu, Xiao-Zhang; Peng, Xiao-Ying; Xing, Li-Qun

2010-01-01

The removal of hexavalent and trivalent chromium from hydroponic solution by plants to changes in temperature was investigated. Pre-rooted hybrid willows (Salix matsudana Koidz x alba L.) were exposed to a nutrient solution spiked with potassium chromate (K(2)CrO(4)) or chromium chloride (CrCl(3)) for 4 days. Ten different temperatures were tested ranging from 11 to 32 degrees C. Total Cr in solutions and in plant materials were all analyzed quantitatively. The results revealed that large amounts of the applied Cr were removed from the hydroponic solution in the presence of the plants. Significantly faster removal of Cr(III) than Cr(VI) was achieved by hybrid willows from the hydroponic solutions at all temperatures (P < 0.01). The removal rates of both chemical forms of Cr by plants increased linearly with the increase of temperatures. The highest removal rate of Cr(VI) was found at 32 degrees C with a value of 1.99 microg Cr/g day, whereas the highest value of Cr(III) was 3.55 microg Cr/g day at the same temperature. Roots were the main sink for Cr accumulation in plants at all temperatures. Translocation of both chemical forms of Cr from roots to lower stems was only found at temperatures > or = 24 degrees C. The temperature coefficient values (Q(10)) were 2.41 and 1.42 for Cr(VI) and Cr(III), respectively, indicating that the removal of Cr(VI) by hybrid willows was much more susceptible to changes in temperature than that of Cr(III). This information suggests that changes in temperature have a substantial influence on the uptake and accumulation of both chemical forms of Cr by plants.

"Cleaning" the Surface of Hydroxyapatite Nanorods by a Reaction-Dissolution Approach.

PubMed

Cao, Binrui; Yang, Mingying; Wang, Lin; Xu, Hong; Zhu, Ye; Mao, Chuanbin

2015-10-21

Synthetic nanoparticles are always terminated with coating molecules, which are often cytotoxic and not desired in biomedicine. Here we propose a novel reaction-dissolution approach to remove the cytotoxic coating molecules. A two-component solution is added to the nanoparticle solution; one component reacts with the coating molecules to form a salt whereas another is a solvent for dissolving and thus removing the salt. As a proof of concept, this work uses a NaOH-ethanol solution to remove the cytotoxic linoleic acid molecules coated on the hydroxyapatite nanorods (HAP-NRs). The removal of the coating molecules not only significantly improves the biocompatibility of HAP-NRs but also enables their oriented attachment into tightly-bound superstructures, which mimic the organized HAP crystals in bone and enamel and can promote the osteogenic differentiation of mesenchymal stem cells. Our reaction-dissolution approach can be extended to the surface "cleaning" of other nanomaterials.

An Improved System for Generation of Diploid Cloned Porcine Embryos Using Induced Pluripotent Stem Cells Synchronized to Metaphase.

PubMed

Kim, Eunhye; Zheng, Zhong; Jeon, Yubyeol; Jin, Yong-Xun; Hwang, Seon-Ung; Cai, Lian; Lee, Chang-Kyu; Kim, Nam-Hyung; Hyun, Sang-Hwan

2016-01-01

Pigs provide outstanding models of human genetic diseases due to their striking similarities with human anatomy, physiology and genetics. Although transgenic pigs have been produced using genetically modified somatic cells and nuclear transfer (SCNT), the cloning efficiency was extremely low. Here, we report an improved method to produce diploid cloned embryos from porcine induced pluripotent stem cells (piPSCs), which were synchronized to the G2/M stage using a double blocking method with aphidicolin and nocodazole. The efficiency of this synchronization method on our piPSC lines was first tested. Then, we modified our traditional SCNT protocol to find a workable protocol. In particular, the removal of a 6DMAP treatment post-activation enhanced the extrusion rate of pseudo-second-polar bodies (p2PB) (81.3% vs. 15.8%, based on peak time, 4hpa). Moreover, an immediate activation method yielded significantly more blastocysts than delayed activation (31.3% vs. 16.0%, based on fused embryos). The immunofluorescent results confirmed the effect of the 6DMAP treatment removal, showing remarkable p2PB extrusion during a series of nuclear transfer procedures. The reconstructed embryos from metaphase piPSCs with our modified protocol demonstrated normal morphology at 2-cell, 4-cell and blastocyst stages and a high rate of normal karyotype. This study demonstrated a new and efficient way to produce viable cloned embryos from piPSCs when synchronized to the G2/M phase of the cell cycle, which may lead to opportunities to produce cloned pigs from piPSCs more efficiently.

Metals and metalloid bioconcentrations in the tissues of Typha latifolia grown in the four interconnected ponds of a domestic landfill site.

PubMed

Ben Salem, Zohra; Laffray, Xavier; Al-Ashoor, Ahmed; Ayadi, Habib; Aleya, Lotfi

2017-04-01

The uptake of metals in roots and their transfer to rhizomes and above-ground plant parts (stems, leaves) of cattails (Typha latifolia L.) were studied in leachates from a domestic landfill site (Etueffont, France) and treated in a natural lagooning system. Plant parts and corresponding water and sediment samples were taken at the inflow and outflow points of the four ponds at the beginning and at the end of the growing season. Concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni and Zn in the different compartments were estimated and their removal efficiency assessed, reaching more than 90% for Fe, Mn and Ni in spring and fall as well in the water compartment. The above- and below-ground cattail biomass varied from 0.21 to 0.85, and 0.34 to 1.24kgdryweight/m 2 , respectively, the highest values being recorded in the fourth pond in spring 2011. The root system was the first site of accumulation before the rhizome, stem and leaves. The highest metal concentration was observed in roots from cattails growing at the inflow of the system's first pond. The trend in the average trace element concentrations in the cattail plant organs can generally be expressed as: Fe>Mn>As > Zn>Cr>Cu>Ni>Cd for both spring and fall. While T. latifolia removes trace elements efficiently from landfill leachates, attention should also be paid to the negative effects of these elements on plant growth. Copyright © 2016. Published by Elsevier B.V.

Do Tree Stems Recapture Respired CO2?

NASA Astrophysics Data System (ADS)

Hilman, B.; Angert, A.

2016-12-01

Tree stem respiration is an important, yet not well understood, component of the terrestrial carbon cycle. Predicting how trees as whole organisms respond to changes in climate and atmospheric CO2 requires understanding of the variability in the fraction of assimilated carbon allocated to respiration, versus the allocation to growth, damage repair, and to rhizosphere symbionts. Here we used the ratio of CO2 efflux/O2 influx (Apparent Respiratory Quotient, ARQ) to study stem respiration. The ARQ in trees stems is predicted to be 1.0, as a result of carbohydrates metabolism. Lower than 1.0 ARQ values may indicate a local assimilation of respired CO2, or dissolution and transport of CO2 in the xylem stream. We measured stems ARQ in 16 tree species at tropical, Mediterranean and temperate ecosystems using stem chambers and in-vitro incubations. The CO2 and O2 were measured by a system we developed, which is based on an IRGA and a Fuel-cell O2 analyzer (Hilman and Angert 2016). We found typical values of ARQ in the range of 0.4-0.8. Since incubations of detach stem tissues yielded similar ARQ values, and since the influence of natural variations in the transpiration stream on ARQ was found to be small, we conclude that the removal of the respired CO2 is not via dissolution in the xylem stream. Using 13C labeling, dark fixation of stem tissues was detected, which is most probably phosphoenolpyruvate carboxylase (PEPC) mediated. Hence, we suggest that in-stem dark fixation of respired CO2 to organic acids (e.g. malate) affects the outgoing efflux. Further research should determine if these organic acids are transported to the canopy, stored in the stem, or transported to the roots to serve as exudates. Hilman B, Angert A (2016) Measuring the ratio of CO2 efflux to O2 influx in tree stem respiration. Tree Physiol 2016, doi: 10.1093/treephys/tpw057

Adult stem cell-based apexogenesis

PubMed Central

Li, Yao; Shu, Li-Hong; Yan, Ming; Dai, Wen-Yong; Li, Jun-Jun; Zhang, Guang-Dong; Yu, Jin-Hua

2014-01-01

Generally, the dental pulp needs to be removed when it is infected, and root canal therapy (RCT) is usually required in which infected dental pulp is replaced with inorganic materials (paste and gutta percha). This treatment approach ultimately brings about a dead tooth. However, pulp vitality is extremely important to the tooth itself, since it provides nutrition and acts as a biosensor to detect the potential pathogenic stimuli. Despite the reported clinical success rate, RCT-treated teeth are destined to be devitalized, brittle and susceptible to postoperative fracture. Recently, the advances and achievements in the field of stem cell biology and regenerative medicine have inspired novel biological approaches to apexogenesis in young patients suffering from pulpitis or periapical periodontitis. This review mainly focuses on the benchtop and clinical regeneration of root apex mediated by adult stem cells. Moreover, current strategies for infected pulp therapy are also discussed here. PMID:25332909

An Unexpected Complication of Residual Fibular Strut Graft While Performing A Press fit Hemiarthroplasty for A Secondary Nonunion Fracture Neck of the Femur.

PubMed

Huda, Najmul; Julfiqar; Pant, Ajay; Aslam, M

2015-01-01

Perioperative complications are well known during partial and total hip arthroplasty. One of the common categories of these complications is an intraoperative fractures of the proximal femur. Here we discuss a case of perforation of posteromedial cortex of the proximal femur, while doing a press fit modular bipolar hemiarthroplasty, in a young adult with secondary nonunion of the femoral neck fracture. The cause of this proximal femur perforation was residual fibular strut graft that, redirected the femoral stem into undesirable direction. This complication of residual fibular strut graft has not been disscussed much in the orthopedic literature previously. A press fit modular bipolar hiparthroplasty was performed in a young adult male with nonunion fracture neck of the femur secondary to initial fixation using 6.5mm cannulated hip screws and nonvascularized free fibular strut grafting. Failure to completely remove the fibular strut from the proximal femur lead to difficult negotiation of the femoral stem into the femoral canal and ultimately a perforation in the proximal femur at the level of the lesser trochanter. A revision procedure was done to completely remove the residual fibular graft, and then a fresh press fit modular bipolar hemiarthroplasty was done. Complete removal of fibular strut graft should be done, while performing hip arthroplasty in patients with failed fibular grafting for fracture neck of the femur.

Gravitropism in Higher Plant Shoots 1

PubMed Central

Sliwinski, Julianne E.; Salisbury, Frank B.

1984-01-01

Cross and longitudinal sections were prepared for light microscopy from vertical control plants (Xanthium strumarium L. Chicago strain), free-bending horizontal stems, plants restrained 48 hours in a horizontal position, and plants restrained 48 hours and then released, bending immediately about 130°. Top cells of free-bending stems shrink or elongate little; bottom cells continue to elongate. In restrained stems, bottom cells elongate some and increase in diameter; top cells elongate about as much but decrease in diameter. Upon release, bottom cells elongate more and decrease in diameter, while top cells shorten and increase in diameter, accounting for the bend. During restraint, bottom cells take up water while tissue pressures increase; top cells fail to take up water although tissue pressures are decreasing. Settling of amyloplasts was observed in cells of the starch sheath. Removal of different amounts of stem (Xanthium; Lycopersicon esculentum Miller, cv Bonny Best; Ricinus communis L. cv Yolo Wonder) showed that perception of gravity occurs in the bending (elongation) zone, although bending of fourth and fifth internodes from the top was less than in uncut controls. Uniform application of 1% indoleacetic acid in lanolin to cut stem surfaces partially restored bending. Reversing the gradient in tension/compression in horizontal stems (top under compression, bottom under tension) did not affect gravitropic bending. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 PMID:16663939

Recovery efficiency of whole-tree harvesting

Treesearch

Bryce J. Stokes; William F. Watson

1988-01-01

The recovery of total tree biomass and most components of a stand is a practical economic and management alternative to tree-length harvesting. First, the increased utilization of woody biomass provides additional revenues from the site. Second, the removal and utilization of the stems and crowns reduces site preparation costs and makes tree planting easier. Third,...

Small-diameter trees used for chemithermomechanical pulps.

Treesearch

Gary C. Myers; R. James Barbour; Said M. Abubakr

1999-01-01

During the course of restoring and maintaining forest ecosystem health and function in the western interior of the United States, many small-diameter stems are removed from densely stocked stands. In general, these materials are considered nonusable or underutilized. Information on the properties of these resources is needed to help managers understand when timber...

Biomass utilization for bioenergy in the Western United States

Treesearch

D.L. Nicholls; R. Monserud; D. Dykstra

2008-01-01

Wildfires, hazardous fuel buildups, small-diameter timber, wildland-urban interface zones, biomass. These are some of the terms becoming familiar to communities throughout the Western United States after the record-breaking fire seasons of the past decade. Although small-diameter stems are generally expensive to remove and often have limited utilization options, the...

Planning Consumer Education Programs for Residents of Prisons and Pre-Release Centers.

ERIC Educational Resources Information Center

Southern Illinois Univ., Carbondale. Dept. of Family Economics and Management.

The pamphlet describes the development of a consumer education program for prison inmates, and presents 12 curriculum guides on consumer topics relevant to prisoners. Because prison inmates spend time removed from the changing economic marketplace, and because many crimes stem from financial and economic problems, it is important to educate and…

Reproduction capacity of Potamogeton crispus fragments and its role in water purification and algae inhibition in eutrophic lakes.

PubMed

Zhou, Yiwen; Zhou, Xiaohong; Han, Ruiming; Xu, Xiaoguang; Wang, Guoxiang; Liu, Xiansheng; Bi, Fengzhi; Feng, Deyou

2017-02-15

The role of fragments in restoring eutrophic lakes remains unclear despite the importance of re-establishing submerged macrophytes via fragments. This study established a manipulative experiment using different biomass fragments of Potamogeton crispus. This approach was adapted to study the reproductive capacity, nutrient removal efficiency, and algae inhibitory effect of fragments. Results showed that fragments could grow throughout a 49-day experiment by maintaining the stable photosynthesis efficiency of leaves and lengthening the stems. These floating fragments could regenerate by producing turions for the maintenance of their species. Moreover, the increasing removal efficiency of TP, TN, NH 4 + -N, and NO 3 - -N in water with the increase of fragment biomass indicates that the fragments could effectively purify water quality. Floating fragments competed with algae for nutrients, occupied a favorable ecological niche, and reduced algae biomass. They altered the structure of algae community and shifted the dominated green algae to cyanobacteria, the green algae of phytoplankton, and benthic algae. Findings imply that the postponable regulation of fragments is necessary for the ecological restoration of eutrophic lakes. Copyright © 2016 Elsevier B.V. All rights reserved.

Revolving scanning transmission electron microscopy: correcting sample drift distortion without prior knowledge.

PubMed

Sang, Xiahan; LeBeau, James M

2014-03-01

We report the development of revolving scanning transmission electron microscopy--RevSTEM--a technique that enables characterization and removal of sample drift distortion from atomic resolution images without the need for a priori crystal structure information. To measure and correct the distortion, we acquire an image series while rotating the scan coordinate system between successive frames. Through theory and experiment, we show that the revolving image series captures the information necessary to analyze sample drift rate and direction. At atomic resolution, we quantify the image distortion using the projective standard deviation, a rapid, real-space method to directly measure lattice vector angles. By fitting these angles to a physical model, we show that the refined drift parameters provide the input needed to correct distortion across the series. We demonstrate that RevSTEM simultaneously removes the need for a priori structure information to correct distortion, leads to a dramatically improved signal-to-noise ratio, and enables picometer precision and accuracy regardless of drift rate. Copyright © 2013 Elsevier B.V. All rights reserved.

Valve leakage inspection, testing, and maintenance process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aikin, J.A.; Reinwald, J.W.

1989-01-01

Atomic Energy of Canada Limited-Research Company (AECL-RC), Chalk River, has more than 50 person-years dedicated toward the leak-free valve. In the early 1970s, the Chalk River Nuclear Laboratories (CRNL) developed valve stem live-loading and recently completed the packing tests for the Electric Power Research Institute (EPRI)-funded Valve Packing Improvement Study. Current safety concerns with asbestos-based valve packings and the difficulty in removing newer graphite packings prompted CRNL to investigate methods to improve valve repacking procedures. The present practice of valve packing replacement is very labor-intensive, requiring use of hand tools such as corkscrew devices and special packing picks. Use ofmore » water jets to cut or fragment the packing for withdrawal from the stuffing box does improve the process, but removal of the lantern or junk rings is still difficult. To address these problems, AECL-RC has developed a unique valve maintenance process designed to reduce person-rem exposures, the risk of scoring the stem or stuffing box, and maintenance costs and to improve the engineering quality of valve repair.« less

Climate alters response of an endemic island plant to removal of invasive herbivores.

PubMed

McEachern, A Kathryn; Thomson, Diane M; Chess, Katherine A

2009-09-01

Islands experience higher rates of species extinction than mainland ecosystems, with biological invasions among the leading causes; they also serve as important model systems for testing ideas in basic and applied ecology. Invasive removal programs on islands are conservation efforts that can also be viewed as powerful manipulative experiments, but few data are available to evaluate their effects. We collected demographic and herbivore damage data for Castilleja mollis Pennell, an endangered plant endemic to Santa Rosa Island, California, over a 12-year period before, during, and after the implementation of control for introduced cattle, deer, and elk. We used these long-term data to explore mechanisms underlying herbivore effects, assess the results of herbivore reduction at the scales of both individual plants and populations, and determine how temporal variability in herbivory and plant demography influenced responses to herbivore removals. For individual plants, herbivore effects mediated by disturbance were greater than those of grazing. Deer and elk scraping of the ground substantially increased plant mortality and dormancy and reduced flowering and growth. Stem damage from browsing did not affect survivorship but significantly reduced plant growth and flower production. Herbivore control successfully lowered damage rates, which declined steeply between 1997 and 2000 and have remained relatively low. Castilleja mollis abundances rose sharply after 1997, suggesting a positive effect of herbivore control, but then began to decline steadily again after 2003. The recent decline appears to be driven by higher mean growing season temperatures; interestingly, not only reductions in scraping damage but a period of cooler conditions were significant in explaining increases in C. mollis populations between 1997 and 2002. Our results demonstrate strong effects of introduced herbivores on both plant demography and population dynamics and show that climate-driven variation may counteract and mask positive responses to herbivore removal. Regional mean temperatures already have risen significantly over the last 50 years, suggesting that climate change could increasingly swamp the effects of management targeted at other environmental problems. Similar interactions between climate and invasive species will play an even greater role in future management, with long-term data sets like this critical to quantifying such effects.

Climate alters response of an endemic island plant to removal of invasive herbivores

USGS Publications Warehouse

Kathryn, Mceachern A.; Thomson, D.M.; Chess, K.A.

2009-01-01

Islands experience higher rates of species extinction than mainland ecosystems, with biological invasions among the leading causes; they also serve as important model systems for testing ideas in basic and applied ecology. Invasive removal programs on islands are conservation efforts that can also be viewed as powerful manipulative experiments, but few data are available to evaluate their effects. We collected demographic and herbivore damage data for Castilleja mollis Pennell, an endangered plant endemic to Santa Rosa Island, California, over a 12-year period before, during, and after the implementation of control for introduced cattle, deer, and elk. We used these long-term data to explore mechanisms underlying herbivore effects, assess the results of herbivore reduction at the scales of both individual plants and populations, and determine how temporal variability in herbivory and plant demography influenced responses to herbivore removals. For individual plants, herbivore effects mediated by disturbance were greater than those of grazing. Deer and elk scraping of the ground substantially increased plant mortality and dormancy and reduced flowering and growth. Stem damage from browsing did not affect survivorship but significantly reduced plant growth and flower production. Herbivore control successfully lowered damage rates, which declined steeply between 1997 and 2000 and have remained relatively low. Castilleja mollis abundances rose sharply after 1997, suggesting a positive effect of herbivore control, but then began to decline steadily again after 2003. The recent decline appears to be driven by higher mean growing season temperatures; interestingly, not only reductions in scraping damage but a period of cooler conditions were significant in explaining increases in C. mollis populations between 1997 and 2002. Our results demonstrate strong effects of introduced herbivores on both plant demography and population dynamics and show that climate-driven variation may counteract and mask positive responses to herbivore removal. Regional mean temperatures already have risen significantly over the last 50 years, suggesting that climate change could increasingly swamp the effects of management targeted at other environmental problems. Similar interactions between climate and invasive species will play an even greater role in future management, with long-term data sets like this critical to quantifying such effects. ?? 2009 by the Ecological Society of America.

A role for adult TLX-positive neural stem cells in learning and behaviour.

PubMed

Zhang, Chun-Li; Zou, Yuhua; He, Weimin; Gage, Fred H; Evans, Ronald M

2008-02-21

Neurogenesis persists in the adult brain and can be regulated by a plethora of external stimuli, such as learning, memory, exercise, environment and stress. Although newly generated neurons are able to migrate and preferentially incorporate into the neural network, how these cells are molecularly regulated and whether they are required for any normal brain function are unresolved questions. The adult neural stem cell pool is composed of orphan nuclear receptor TLX-positive cells. Here, using genetic approaches in mice, we demonstrate that TLX (also called NR2E1) regulates adult neural stem cell proliferation in a cell-autonomous manner by controlling a defined genetic network implicated in cell proliferation and growth. Consequently, specific removal of TLX from the adult mouse brain through inducible recombination results in a significant reduction of stem cell proliferation and a marked decrement in spatial learning. In contrast, the resulting suppression of adult neurogenesis does not affect contextual fear conditioning, locomotion or diurnal rhythmic activities, indicating a more selective contribution of newly generated neurons to specific cognitive functions.

Retinal pigment epithelium culture;a potential source of retinal stem cells.

PubMed

Akrami, Hassan; Soheili, Zahra-Soheila; Khalooghi, Keynoush; Ahmadieh, Hamid; Rezaie-Kanavi, Mojgan; Samiei, Shahram; Davari, Malihe; Ghaderi, Shima; Sanie-Jahromi, Fatemeh

2009-07-01

To establish human retinal pigment epithelial (RPE) cell culture as a source for cell replacement therapy in ocular diseases. Human cadaver globes were used to isolate RPE cells. Each globe was cut into several pieces of a few millimeters in size. After removing the sclera and choroid, remaining tissues were washed in phosphate buffer saline and RPE cells were isolated using dispase enzyme solution and cultured in Dulbecco's Modified Eagle's Medium: Nutrient Mixture F-12 supplemented with 10% fetal calf serum. Primary cultures of RPE cells were established and spheroid colonies related to progenitor/stem cells developed in a number of cultures. The colonies included purely pigmented or mixed pigmented and non-pigmented cells. After multiple cellular passages, several types of photoreceptors and neural-like cells were detected morphologically. Cellular plasticity in RPE cell cultures revealed promising results in terms of generation of stem/progenitor cells from human RPE cells. Whether the spheroids and neural-like retinal cells were directly derived from retinal stem cells or offspring of trans-differentiating or de-differentiating RPE cells remains to be answered.

Retinal Pigment Epithelium Culture;a Potential Source of Retinal Stem Cells

PubMed Central

Akrami, Hassan; Soheili, Zahra-Soheila; Khalooghi, Keynoush; Ahmadieh, Hamid; Rezaie-Kanavi, Mojgan; Samiei, Shahram; Davari, Malihe; Ghaderi, Shima; Sanie-Jahromi, Fatemeh

2009-01-01

Purpose To establish human retinal pigment epithelial (RPE) cell culture as a source for cell replacement therapy in ocular diseases. Methods Human cadaver globes were used to isolate RPE cells. Each globe was cut into several pieces of a few millimeters in size. After removing the sclera and choroid, remaining tissues were washed in phosphate buffer saline and RPE cells were isolated using dispase enzyme solution and cultured in Dulbecco’s Modified Eagle’s Medium: Nutrient Mixture F-12 supplemented with 10% fetal calf serum. Results Primary cultures of RPE cells were established and spheroid colonies related to progenitor/stem cells developed in a number of cultures. The colonies included purely pigmented or mixed pigmented and non-pigmented cells. After multiple cellular passages, several types of photoreceptors and neural-like cells were detected morphologically. Conclusion Cellular plasticity in RPE cell cultures revealed promising results in terms of generation of stem/progenitor cells from human RPE cells. Whether the spheroids and neural-like retinal cells were directly derived from retinal stem cells or offspring of trans-differentiating or de-differentiating RPE cells remains to be answered. PMID:23198062

Influence of the Typha community on mine drainage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snyder, C.D.; Aharrah, E.C.

1984-12-01

This study investigated potential positive influences of the Typha community on mine drainage. The pH increased as the water flowed through two, two-pond systems, and the iron and manganese concentrations decreased. The water quality remained constant or deteriorated in non-vegetated ponds. Typha from the ponds and a non-mined site were assayed for iron and manganese. Roots/rhizomes concentrated the most iron, while the exterior stem layers contained more iron than the remaining stems or leaves. Manganese concentrations were similar in the roots/rhizomes, the leaves, and the exterior stem layers, while stems contained less. Iron concentrations in the Typha from June andmore » September were similar, but manganese concentrations in these Typha were different. Typha from mined sites accumulated more iron and manganese in the roots/rhizomes than Typha from non-mined sites. Bacteria and algae were identified and numerous species which function as oxidizers were recorded. These microbes play an important role in the Typha community and should also be considered in future studies as agents in the removal of metallic ions.« less

The Effect of STEM Learning through the Project of Designing Boat Model toward Student STEM Literacy

NASA Astrophysics Data System (ADS)

Tati, T.; Firman, H.; Riandi, R.

2017-09-01

STEM Learning focusses on development of STEM-literate society, the research about implementation of STEM learning to develope students’ STEM literacy is still limited. This study is aimed to examine the effect of implementation STEM learning through the project of designing boat model on students STEM literacy in energy topic. The method of this study was a quasi-experiment with non-randomized pretest-posttest control group design. There were two classes involved, the experiment class used Project Based Learning with STEM approach and control class used Project-Based Learning without STEM approach. A STEM Literacy test instrument was developed to measure students STEM literacy which consists of science literacy, mathematics literacy, and technology-engineering literacy. The analysis showed that there were significant differences on improvement science literacy, mathematics technology-engineering between experiment class and control class with effect size more than 0.8 (large effect). The difference of improvement of STEM literacy between experiment class and control class is caused by the existence of design engineering activity which required students to apply the knowledge from every field of STEM. The challenge that was faced in STEM learning through design engineering activity was how to give the students practice to integrate STEM field in solving the problems. In additional, most of the students gave positive response toward implementation of STEM learning through design boat model project.

Investigating Preservice STEM Teacher Conceptions of STEM Education

NASA Astrophysics Data System (ADS)

Radloff, Jeff; Guzey, Selcen

2016-10-01

Surrounding the national emphasis on improving STEM education, effective STEM educators are required. Connected, yet often overlooked, is the need for effective preservice STEM teaching instruction for incoming educators. At a basic level, preservice STEM teacher education should include STEM content, pedagogy, and conceptualization. However, the literature suggests no leading conception of STEM education, and little is known about how preservice STEM teachers are conceptualizing STEM education. In order to explore preservice STEM teacher conceptions of STEM education, preservice teachers at a large, Midwestern research university were given an open-ended survey eliciting both textual and visual responses. Here, we report and discuss the results of employing this instrument in relation with the current STEM conceptualization literature.

Soluble Expression of Human Leukemia Inhibitory Factor with Protein Disulfide Isomerase in Escherichia coli and Its Simple Purification

PubMed Central

Chong, Seon-Ha; Kim, Kyunhoo; Choi, Dong Kyu; Thi Vu, Thu Trang; Nguyen, Minh Tan; Jeong, Boram; Ryu, Han-Bong; Kim, Injune; Jang, Yeon Jin; Robinson, Robert Charles; Choe, Han

2013-01-01

Human leukemia inhibitory factor (hLIF) is a multifunctional cytokine that is essential for maintaining the pluripotency of embryonic stem cells. hLIF may be also be useful in aiding fertility through its effects on increasing the implantation rate of fertilized eggs. Thus these applications in biomedical research and clinical medicine create a high demand for bioactive hLIF. However, production of active hLIF is problematic since eukaryotic cells demonstrate limited expression and prokaryotic cells produce insoluble protein. Here, we have adopted a hybrid protein disulfide isomerase design to increase the solubility of hLIF in Escherichia coli. Low temperature expression of hLIF fused to the b'a' domain of protein disulfide isomerase (PDIb'a') increased the soluble expression in comparison to controls. A simple purification protocol for bioactive hLIF was established that includes removal of the PDIb'a' domain by cleavage by TEV protease. The resulting hLIF, which contains one extra glycine residue at the N-terminus, was highly pure and demonstrated endotoxin levels below 0.05 EU/μg. The presence of an intramolecular disulfide bond was identified using mass spectroscopy. This purified hLIF effectively maintained the pluripotency of a murine embryonic stem cell line. Thus we have developed an effective method to produce a pure bioactive version of hLIF in E. coli for use in biomedical research. PMID:24358310

Effects of a discoloration-resistant calcium aluminosilicate cement on the viability and proliferation of undifferentiated human dental pulp stem cells.

PubMed

Niu, Li-na; Watson, Devon; Thames, Kyle; Primus, Carolyn M; Bergeron, Brian E; Jiao, Kai; Bortoluzzi, Eduardo A; Cutler, Christopher W; Chen, Ji-hua; Pashley, David H; Tay, Franklin R

2015-11-30

Discoloration-resistant calcium aluminosilicate cement has been formulated to overcome the timely problem of tooth discoloration reported in the clinical application of bismuth oxide-containing hydraulic cements. The present study examined the effects of this experimental cement (Quick-Set2) on the viability and proliferation of human dental pulp stem cells (hDPSCs) by comparing the cellular responses with commercially available calcium silicate cement (white mineral trioxide aggregate; WMTA) after different aging periods. Cell viability and proliferation were examined using assays that examined plasma membrane integrity, leakage of cytosolic enzyme, caspase-3 activity for early apoptosis, oxidative stress, mitochondrial metabolic activity and intracellular DNA content. Results of the six assays indicated that both Quick-Set2 and WMTA were initially cytotoxic to hDPSCs after setting for 24 h, with Quick-Set2 being comparatively less cytotoxic than WMTA at this stage. After two aging cycles, the cytotoxicity profiles of the two hydraulic cements were not significantly different and were much less cytotoxic than the positive control (zinc oxide-eugenol cement). Based on these results, it is envisaged that any potential beneficial effect of the discoloration-resistant calcium aluminosilicate cement on osteogenesis by differentiated hDPSCs is more likely to be revealed after outward diffusion and removal of its cytotoxic components.

Effects of a discoloration-resistant calcium aluminosilicate cement on the viability and proliferation of undifferentiated human dental pulp stem cells

PubMed Central

Niu, Li-na; Watson, Devon; Thames, Kyle; Primus, Carolyn M.; Bergeron, Brian E.; Jiao, Kai; Bortoluzzi, Eduardo A.; Cutler, Christopher W.; Chen, Ji-hua; Pashley, David H.; Tay, Franklin R.

2015-01-01

Discoloration-resistant calcium aluminosilicate cement has been formulated to overcome the timely problem of tooth discoloration reported in the clinical application of bismuth oxide-containing hydraulic cements. The present study examined the effects of this experimental cement (Quick-Set2) on the viability and proliferation of human dental pulp stem cells (hDPSCs) by comparing the cellular responses with commercially available calcium silicate cement (white mineral trioxide aggregate; WMTA) after different aging periods. Cell viability and proliferation were examined using assays that examined plasma membrane integrity, leakage of cytosolic enzyme, caspase-3 activity for early apoptosis, oxidative stress, mitochondrial metabolic activity and intracellular DNA content. Results of the six assays indicated that both Quick-Set2 and WMTA were initially cytotoxic to hDPSCs after setting for 24 h, with Quick-Set2 being comparatively less cytotoxic than WMTA at this stage. After two aging cycles, the cytotoxicity profiles of the two hydraulic cements were not significantly different and were much less cytotoxic than the positive control (zinc oxide–eugenol cement). Based on these results, it is envisaged that any potential beneficial effect of the discoloration-resistant calcium aluminosilicate cement on osteogenesis by differentiated hDPSCs is more likely to be revealed after outward diffusion and removal of its cytotoxic components. PMID:26617338

Conical Seat Shut-Off Valve

NASA Technical Reports Server (NTRS)

Farner, Bruce

2013-01-01

A moveable valve for controlling flow of a pressurized working fluid was designed. This valve consists of a hollow, moveable floating piston pressed against a stationary solid seat, and can use the working fluid to seal the valve. This open/closed, novel valve is able to use metal-to-metal seats, without requiring seat sliding action; therefore there are no associated damaging effects. During use, existing standard high-pressure ball valve seats tend to become damaged during rotation of the ball. Additionally, forces acting on the ball and stem create large amounts of friction. The combination of these effects can lead to system failure. In an attempt to reduce damaging effects and seat failures, soft seats in the ball valve have been eliminated; however, the sliding action of the ball across the highly loaded seat still tends to scratch the seat, causing failure. Also, in order to operate, ball valves require the use of large actuators. Positioning the metal-to-metal seats requires more loading, which tends to increase the size of the required actuator, and can also lead to other failures in other areas such as the stem and bearing mechanisms, thus increasing cost and maintenance. This novel non-sliding seat surface valve allows metal-to-metal seats without the damaging effects that can lead to failure, and enables large seating forces without damaging the valve. Additionally, this valve design, even when used with large, high-pressure applications, does not require large conventional valve actuators and the valve stem itself is eliminated. Actuation is achieved with the use of a small, simple solenoid valve. This design also eliminates the need for many seals used with existing ball valve and globe valve designs, which commonly cause failure, too. This, coupled with the elimination of the valve stem and conventional valve actuator, improves valve reliability and seat life. Other mechanical liftoff seats have been designed; however, they have only resulted in increased cost, and incurred other reliability issues. With this novel design, the seat is lifted by simply removing the working fluid pressure that presses it against the seat and no external force is required. By eliminating variables associated with existing ball and globe configurations that can have damaging effects upon a valve, this novel design reduces downtime in rocket engine test schedules and maintenance costs.

Invasive Australian Acacia seed banks: Size and relationship with stem diameter in the presence of gall-forming biological control agents.

PubMed

Strydom, Matthys; Veldtman, Ruan; Ngwenya, Mzabalazo Z; Esler, Karen J

2017-01-01

Australian Acacia are invasive in many parts of the world. Despite significant mechanical and biological efforts to control their invasion and spread, soil-stored seed banks prevent their effective and sustained removal. In response South Africa has had a strong focus on employing seed reducing biological control agents to deal with Australian Acacia invasion, a programme that is considered as being successful. To provide a predictive understanding for their management, seed banks of four invasive Australian acacia species (Acacia longifolia, A. mearnsii, A. pycnantha and A. saligna) were studied in the Western Cape of South Africa. Across six to seven sites for each species, seed bank sizes were estimated from dense, monospecific stands by collecting 30 litter and soil samples. Average estimated seed bank size was large (1017 to 17261 seed m-2) as was annual input into the seed bank, suggesting that these seed banks are not residual but are replenished in size annually. A clear relationship between seed bank size and stem diameter was established indicating that mechanical clearing should be conducted shortly after fire-stimulated recruitment events or within old populations when seed banks are small. In dense, monospecific stands seed-feeding biological control agents are not effective in reducing seed bank size.

Immuno- and gene expression analysis of EGFR and Nestin during mice skin development.

PubMed

Falodah, Fawaz Adnan; Al-Karim, Saleh

2016-06-01

Skin stem cell populations reside in the adult hair follicle, sebaceous gland, dermis and epidermis. However, the origin of most of the stem cell populations found in the adult epidermis is still unknown. Far more unknown is the embryonic origin of other stem cells that populate the other layers of this tissue. The main objectives of the present study were to identify the precise anatomical localization of stem cells in mice during skin developing; and to determine the expression levels by using immuno- and gene expression analysis. In this comparative cross sectional study, six ages been chosen and divided into: embryonic days (E12.5, E14.5 and E19.5) and litter days (L7, L14 and L19). Skin were removed from the back side and processed to assess both immuno- and gene-expression of EGFR and Nestin surface antigen markers. Data of the different studied age groups was compared using the SPSS software. EGFR was mainly expressed in the outer root sheath (ORS), in basal and, to a lesser extent, in suprabasal keratinocytes and tend to lie where the dermis comes closest to the skin surface, while Nestin expressed throughout the dermis in the early embryo, but it is subsequently restricted to the follicular connective tissue sheaths later in development and to hair follicles after birth. Immunoexpression analysis showed a strong EGFR expression in all group ages except E12.5 which recorded as moderate, while Nestin showed strong expression level for all embryonic stages, while in the litters it was moderate. The qRT-PCR results were consistent with those of the immunohistochemical study. The Pearson correlation analyze present a correlation between the cases of study with age (p≤0.01), which indicated to the effect of age to mice development. EGFR and Nestin showed to have vital role during mice development, and considered to be suitable markers for the study of skin stem cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

Heavy metal bioaccumulation by Miscanthus sacchariflorus and its potential for removing metals from the Dongting Lake wetlands, China.

PubMed

Yao, Xin; Niu, Yandong; Li, Youzhi; Zou, Dongsheng; Ding, Xiaohui; Bian, Hualin

2018-05-09

Bioaccumulation of five heavy metals (Cd, Cu, Mn, Pb, and Zn) in six plant organs (panicle, leaf, stem, root, rhizome, and bud) of the emergent and perennial plant species, Miscanthus sacchariflorus, were investigated to estimate the plant's potential for accumulating heavy metals in the wetlands of Dongting Lake. We found the highest Cd concentrations in the panicles and leaves; while the highest Cu and Mn were observed in the roots, the highest Pb in the panicles, and the highest Zn in the panicles and buds. In contrast, the lowest Cd concentrations were detected in the stem, roots, and buds; the lowest Cu concentrations in the leaves and stems; the lowest Mn concentrations in the panicles, rhizomes, and buds; the lowest Pb concentrations in the stems; and the lowest Zn concentrations in the leaves, stems, and rhizomes. Mean Cu concentration in the plant showed a positive regression coefficient with plot elevation, soil organic matter content, and soil Cu concentration, whereas it showed a negative regression coefficient with soil moisture and electrolyte leakage. Mean Mn concentration showed positive and negative regression coefficients with soil organic matter and soil moisture, respectively. Mean Pb concentration exhibited positive regression coefficient with plot elevation and soil total P concentration, and Zn concentration showed a positive regression coefficient with soil available P and total P concentrations. However, there was no significant regression coefficient between mean Cd concentration in the plant and the investigated environmental parameters. Stems and roots were the main organs involved in heavy metal accumulation from the environment. The mean quantities of heavy metals accumulated in the plant tissues were 2.2 mg Cd, 86.7 mg Cu, 290.3 mg Mn, 15.9 mg Pb, and 307 mg Zn per square meter. In the Dongting Lake wetlands, 0.7 × 10 3  kg Cd, 22.9 × 10 3  kg Cu, 77.5 × 10 3  kg Mn, 3.1 × 10 3  kg Pb, and 95.9 × 10 3  kg Zn per year were accumulated by aboveground organs and removed from the lake through harvesting for paper manufacture.

Ultra-minimally invasive local immune cell therapy and regenerative therapy by multi-piercing surgery for abdominal solid tumor: therapeutic simulation by natural orifice translumenal endoscopic surgery-assisted needlescopic surgery using 3-mm diameter robots.

PubMed

Ohdaira, Takeshi; Tsutsumi, Norifumi; Xu, Hao; Mori, Megumu; Uemura, Munenori; Ieiri, Satoshi; Hashizume, Makoto

2011-07-01

We have invented multi-piercing surgery (MPS) which could potentially solve the triangular formation loss and device clashing which occur in single-port surgery (SPS), as well as restricted visual field, organ damage by needle-type instruments, and impaired removal of a resected organ from the body which occur in needlescopic surgery (NS). MPS is natural orifice translumenal endoscopic surgery (NOTES)-assisted NS. We used 3-mm diameter robots as needle-type instruments for MPS to examine the possibility of local immune cell therapy and regenerative therapy using stem cells for pancreatic cancer. In MPS using two robots, the therapeutic cell suspension was injected into a target region of pancreas in two pigs. Both retention of a capsule of liquid cell suspension and invasive level were evaluated. Triangular formation could be ensured. The use of small-diameter robots allowed (1) the surgical separation of the pancreas and the retroperitoneum, and (2) the formation of the capsule containing the immune cell and stem cell suspension. The endoscope for NOTES provided a clear visual field and also assisted the removal of a resected organ from the body. The visual field of the endoscope could be oriented well by using an electromagnetic navigation system. MPS using small-diameter robots could potentially solve the issues inherent in SPS and NS and could allow minimally invasive local immune cell and stem cell therapy.

Evaluation of 2 Purification Methods for Isolation of Human Adipose-Derived Stem Cells Based on Red Blood Cell Lysis With Ammonium Chloride and Hypotonic Sodium Chloride Solution.

PubMed

Li, Sheng-Hong; Liao, Xuan; Zhou, Tian-En; Xiao, Li-Ling; Chen, Yuan-Wen; Wu, Fan; Wang, Jing-Ru; Cheng, Biao; Song, Jian-Xing; Liu, Hong-Wei

2017-01-01

The present study was conducted to compare 2 purification methods for isolation of human adipose-derived stromal vascular fraction or stem cells (ADSCs) based on red blood cell (RBC) lysis with 155 mM ammonium chloride (NH4Cl) and hypotonic sodium chloride (NaCl) solution, and try to develop a safe, convenient, and cost-effective purification method for clinical applications. Adipose-derived stem cells and RBC were harvested from the fatty and fluid portions of liposuction aspirates, respectively. The suitable concentration of hypotonic NaCl solution on RBC lysis for purification of ADSCs was developed by RBC osmotic fragility test and flow cytometry analysis. The effects of 155 mM NH4Cl or 0.3% NaCl solution on ADSCs proliferation and RBC lysis efficiency were examined by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide assay and lysis efficiency test, respectively. In addition, the adipogenic and osteogenic capabilities, phenotype and genetic stability of ADSCs were evaluated by oil red staining, alkaline phosphatase activity measurement, flow cytometry, and karyotype analysis, respectively. Sodium chloride solution in 0.3% concentration effectively removed RBCs and did not influence the survival of ADSCs in the 10-minute incubation time. The lysis efficiency did not differ significantly between 0.3% NaCl and 155 mM NH4Cl. Moreover, the adipogenic and osteogenic capabilities, surface marker expression and karyotype of the ADSCs were not affected by lysis solutions or by lysis per se. However, the proliferation capacity in the 0.3% NaCl group was superior to that in 155 mM NH4Cl group. Our data suggest that 0.3% NaCl solution is useful for isolating ADSCs from liposuction aspirate for clinical applications with safety, convenience, and cost-effect.

Iron oxide inside SBA-15 modified with amino groups as reusable adsorbent for highly efficient removal of glyphosate from water

NASA Astrophysics Data System (ADS)

Fiorilli, Sonia; Rivoira, Luca; Calì, Giada; Appendini, Marta; Bruzzoniti, Maria Concetta; Coïsson, Marco; Onida, Barbara

2017-07-01

Iron oxide clusters were incorporated into amino-functionalized SBA-15 in order to obtain a magnetically recoverable adsorbent. The physical-chemical properties of the material were characterized by FE-SEM, STEM, XRD, TGA, XPS, FT-IR and acid-base titration analysis. Iron oxide nanoparticles were uniformly dispersed into the pore of mesoporous silica and that the adsorbent is characterized high specific surface area (177 m2/g) and accessible porosity. The sorbent was successfully tested for the removal of glyphosate in real water matrices. Despite the significant content of inorganic ions, a quantitative removal of the contaminant was found. The complete regeneration of the sorbent after the adsorption process through diluted NaOH solution was also proved.

Genome-Wide Association Studies with a Genomic Relationship Matrix: A Case Study with Wheat and Arabidopsis

PubMed Central

Gianola, Daniel; Fariello, Maria I.; Naya, Hugo; Schön, Chris-Carolin

2016-01-01

Standard genome-wide association studies (GWAS) scan for relationships between each of p molecular markers and a continuously distributed target trait. Typically, a marker-based matrix of genomic similarities among individuals (G) is constructed, to account more properly for the covariance structure in the linear regression model used. We show that the generalized least-squares estimator of the regression of phenotype on one or on m markers is invariant with respect to whether or not the marker(s) tested is(are) used for building G, provided variance components are unaffected by exclusion of such marker(s) from G. The result is arrived at by using a matrix expression such that one can find many inverses of genomic relationship, or of phenotypic covariance matrices, stemming from removing markers tested as fixed, but carrying out a single inversion. When eigenvectors of the genomic relationship matrix are used as regressors with fixed regression coefficients, e.g., to account for population stratification, their removal from G does matter. Removal of eigenvectors from G can have a noticeable effect on estimates of genomic and residual variances, so caution is needed. Concepts were illustrated using genomic data on 599 wheat inbred lines, with grain yield as target trait, and on close to 200 Arabidopsis thaliana accessions. PMID:27520956

Phytoremediation of contaminated soils containing gasoline using Ludwigia octovalvis (Jacq.) in greenhouse pots.

PubMed

Al-Mansoory, Asia Fadhile; Idris, Mushrifah; Abdullah, Siti Rozaimah Sheikh; Anuar, Nurina

2017-05-01

Greenhouse experiments were carried out to determine the phytotoxic effects on the plant Ludwigia octovalvis in order to assess its applicability for phytoremediation gasoline-contaminated soils. Using plants to degrade hydrocarbons is a challenging task. In this study, different spiked concentrations of hydrocarbons in soil (1, 2, and 3 g/kg) were tested. The results showed that the mean efficiency of total petroleum hydrocarbon (TPH) removal over a 72-day culture period was rather high. The maximum removal of 79.8 % occurred for the 2 g/kg concentration, while the removal rate by the corresponding unplanted controls was only (48.6 %). The impact of gasoline on plants included visual symptoms of stress, yellowing, growth reduction, and perturbations in the developmental parameters. The dry weight and wet weight of the plant slightly increased upon exposure to gasoline until day 42. Scanning electron microscopy (SEM) indicated change to the root and stem structure in plant tissue due to the direct attachment with gasoline contaminated compared to the control sample. The population of living microorganisms in the contaminated soil was found to be able to adapt to different gasoline concentrations. The results showed that L. octovalvis and rhizobacteria in gasoline-contaminated soil have the potential to degrade organic pollutants.

Characterization of stem cells in Dupuytren's disease.

PubMed

Hindocha, S; Iqbal, S A; Farhatullah, S; Paus, R; Bayat, A

2011-02-01

Dupuytren's disease (DD) is a common fibroproliferative disease of unknown origin. The source of abnormal cells leading to DD formation remains underexplored. In addition to fascia, palmar skin and fat-derived cells may be a potential source of cells causing DD. This study aimed to profile haematopoietic and mesenchymal stem cells in different DD tissue components compared with tissue removed at carpal tunnel surgery (control). Biopsies were taken from the diseased cord, nodule, perinodular fat and skin overlying the nodule of ten patients with DD and compared with control tissue from seven patients having surgery for carpal tunnel syndrome. Fluorescence-activated cell sorting (FACS), immunohistochemistry and quantitative real-time polymerase chain reaction (QRT-PCR) were used to identify expression of selected stem cell markers. FACS and QRT-PCR analysis identified the highest RNA expression and number of cells positive for adipocyte stem cell markers (CD13 and CD29) in the DD nodule in comparison with carpal tunnel control tissue (P = 0·053). CD34 RNA was overexpressed, and a higher percentage of these cells was present in DD skin compared with carpal tunnel skin (P = 0·001). Each structural component of DD (cord, nodule, perinodular fat and skin) had distinct stem cell populations. These findings support the hypothesis that DD may result from mesenchymal progenitor cell expansion.

Improving Underrepresented Minority Student Persistence in STEM.

PubMed

Estrada, Mica; Burnett, Myra; Campbell, Andrew G; Campbell, Patricia B; Denetclaw, Wilfred F; Gutiérrez, Carlos G; Hurtado, Sylvia; John, Gilbert H; Matsui, John; McGee, Richard; Okpodu, Camellia Moses; Robinson, T Joan; Summers, Michael F; Werner-Washburne, Maggie; Zavala, MariaElena

2016-01-01

Members of the Joint Working Group on Improving Underrepresented Minorities (URMs) Persistence in Science, Technology, Engineering, and Mathematics (STEM)-convened by the National Institute of General Medical Sciences and the Howard Hughes Medical Institute-review current data and propose deliberation about why the academic "pathways" leak more for URM than white or Asian STEM students. They suggest expanding to include a stronger focus on the institutional barriers that need to be removed and the types of interventions that "lift" students' interests, commitment, and ability to persist in STEM fields. Using Kurt Lewin's planned approach to change, the committee describes five recommendations to increase URM persistence in STEM at the undergraduate level. These recommendations capitalize on known successes, recognize the need for accountability, and are framed to facilitate greater progress in the future. The impact of these recommendations rests upon enacting the first recommendation: to track successes and failures at the institutional level and collect data that help explain the existing trends. © 2016 M. Estrada et al. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Comprehensive Review of Adipose Stem Cells and Their Implication in Distraction Osteogenesis and Bone Regeneration

PubMed Central

Morcos, Mina W.; Al-Jallad, Hadil; Hamdy, Reggie

2015-01-01

Bone is one of the most dynamic tissues in the human body that can heal following injury without leaving a scar. However, in instances of extensive bone loss, this intrinsic capacity of bone to heal may not be sufficient and external intervention becomes necessary. Several techniques are available to address this problem, including autogenous bone grafts and allografts. However, all these techniques have their own limitations. An alternative method is the technique of distraction osteogenesis, where gradual and controlled distraction of two bony segments after osteotomy leads to induction of new bone formation. Although distraction osteogenesis usually gives satisfactory results, its major limitation is the prolonged duration of time required before the external fixator is removed, which may lead to numerous complications. Numerous methods to accelerate bone formation in the context of distraction osteogenesis have been reported. A viable alternative to autogenous bone grafts for a source of osteogenic cells is mesenchymal stem cells from bone marrow. However, there are certain problems with bone marrow aspirate. Hence, scientists have investigated other sources for mesenchymal stem cells, specifically adipose tissue, which has been shown to be an excellent source of mesenchymal stem cells. In this paper, the potential use of adipose stem cells to stimulate bone formation is discussed. PMID:26448947

Concurrent Isolation of 3 Distinct Cardiac Stem Cell Populations From a Single Human Heart Biopsy.

PubMed

Monsanto, Megan M; White, Kevin S; Kim, Taeyong; Wang, Bingyan J; Fisher, Kristina; Ilves, Kelli; Khalafalla, Farid G; Casillas, Alexandria; Broughton, Kathleen; Mohsin, Sadia; Dembitsky, Walter P; Sussman, Mark A

2017-07-07

The relative actions and synergism between distinct myocardial-derived stem cell populations remain obscure. Ongoing debates on optimal cell population(s) for treatment of heart failure prompted implementation of a protocol for isolation of multiple stem cell populations from a single myocardial tissue sample to develop new insights for achieving myocardial regeneration. Establish a robust cardiac stem cell isolation and culture protocol to consistently generate 3 distinct stem cell populations from a single human heart biopsy. Isolation of 3 endogenous cardiac stem cell populations was performed from human heart samples routinely discarded during implantation of a left ventricular assist device. Tissue explants were mechanically minced into 1 mm 3 pieces to minimize time exposure to collagenase digestion and preserve cell viability. Centrifugation removes large cardiomyocytes and tissue debris producing a single cell suspension that is sorted using magnetic-activated cell sorting technology. Initial sorting is based on tyrosine-protein kinase Kit (c-Kit) expression that enriches for 2 c-Kit + cell populations yielding a mixture of cardiac progenitor cells and endothelial progenitor cells. Flowthrough c-Kit - mesenchymal stem cells are positively selected by surface expression of markers CD90 and CD105. After 1 week of culture, the c-Kit + population is further enriched by selection for a CD133 + endothelial progenitor cell population. Persistence of respective cell surface markers in vitro is confirmed both by flow cytometry and immunocytochemistry. Three distinct cardiac cell populations with individualized phenotypic properties consistent with cardiac progenitor cells, endothelial progenitor cells, and mesenchymal stem cells can be successfully concurrently isolated and expanded from a single tissue sample derived from human heart failure patients. © 2017 American Heart Association, Inc.

Analysis of type II diabetes mellitus adipose-derived stem cells for tissue engineering applications

PubMed Central

Minteer, Danielle Marie; Young, Matthew T; Lin, Yen-Chih; Over, Patrick J; Rubin, J Peter; Gerlach, Jorg C

2015-01-01

To address the functionality of diabetic adipose-derived stem cells in tissue engineering applications, adipose-derived stem cells isolated from patients with and without type II diabetes mellitus were cultured in bioreactor culture systems. The adipose-derived stem cells were differentiated into adipocytes and maintained as functional adipocytes. The bioreactor system utilizes a hollow fiber–based technology for three-dimensional perfusion of tissues in vitro, creating a model in which long-term culture of adipocytes is feasible, and providing a potential tool useful for drug discovery. Daily metabolic activity of the adipose-derived stem cells was analyzed within the medium recirculating throughout the bioreactor system. At experiment termination, tissues were extracted from bioreactors for immunohistological analyses in addition to gene and protein expression. Type II diabetic adipose-derived stem cells did not exhibit significantly different glucose consumption compared to adipose-derived stem cells from patients without type II diabetes (p > 0.05, N = 3). Expression of mature adipocyte genes was not significantly different between diabetic/non-diabetic groups (p > 0.05, N = 3). Protein expression of adipose tissue grown within all bioreactors was verified by Western blotting.The results from this small-scale study reveal adipose-derived stem cells from patients with type II diabetes when removed from diabetic environments behave metabolically similar to the same cells of non-diabetic patients when cultured in a three-dimensional perfusion bioreactor, suggesting that glucose transport across the adipocyte cell membrane, the hindrance of which being characteristic of type II diabetes, is dependent on environment. The presented observation describes a tissue-engineered tool for long-term cell culture and, following future adjustments to the culture environment and increased sample sizes, potentially for anti-diabetic drug testing. PMID:26090087

Stem anatomy and relative growth rate in seedlings of a wide range of woody plant species and types.

PubMed

Castro-Díez, P; Puyravaud, J P; Cornelissen, J H C; Villar-Salvador, P

1998-08-01

Stem traits were analysed in laboratory-grown seedlings of 80 European woody and semiwoody species of known potential relative growth rate (RGR) and of similar ontogenetic phase. The objectives were, firstly, to assess the relation between stem structure and plant growth potential and, secondly, to explore how stem structure varies among species differing in life form and leaf habit. Hydraulic conductance was represented by the mean diameter of the widest xylem conduits (Dmax), and structural strength by the percentage of xylem tissue occupied by cell wall material (CWx) or stem tissue density (SD). Across all species RGR showed a weak positive correlation with Dmax and weak negative ones with CWx and SD, with slow-growers showing great dispersion of stem trait values. In the RGR-Dmax relationship this dispersion disappeared when trees were removed from the analysis. None of the relationships were significant among tree species alone. It was suggested that fast-growers require a xylem with wide conduits (high Dmax) to achieve high hydraulic conductivity, and "cheaply" constructed stems (low CWx and SD) to maximise allocation to leaves. However, the possession of such traits does not guarantee fast growth, as other factors may constrain RGR elsewhere in the plant. Deciduous seedlings showed higher Dmax and lower CWx than evergreens. Higher Dmax could reflect an innate higher tolerance of conductivity loss by freeze-induced embolism in deciduous plants, which are not burdened by the maintenance of foliage in winter. In contrast, life forms were differentiated most clearly by SD. For instance, shrub seedlings had less dense stem tissues than tree seedlings, possibly because they need less investment in long-term strength and stature.

Effect of available nitrogen on phytoavailability and bioaccumulation of hexavalent and trivalent chromium in hankow willows (Salix matsudana Koidz).

PubMed

Yu, Xiao-Zhang; Gu, Ji-Dong

2008-06-01

The effect of available nitrogen in nutrient solution on removal of two chemical forms of chromium (Cr) by plants was investigated. Pre-rooted hankow willows (Salix matsudana Koidz) were grown in a hydroponic solution system with or without nitrogen, and amended with hexavalent chromium [Cr (VI)] or trivalent chromium [Cr (III)] at 25.0+/-0.5 degrees C for 192 h. The results revealed that higher removal of Cr by plants was achieved from the hydroponic solutions without any nitrogen than those containing nitrogen. Although faster removal of Cr (VI) than Cr (III) was observed, translocation of Cr (III) within plant materials was more efficient than Cr (VI). Substantial difference existed in the distribution of Cr in different parts of plant tissues due to the nitrogen in nutrient solutions (p<0.05): lower stems were the major sink for both Cr species in willows grown in the N-free nutrient solutions and more Cr was accumulated in the roots of plants in N-containing ones. No significant difference was found in the removal rate of Cr (VI) between willows grown in the N-free and N-containing solutions (p>0.05). Removal rates of Cr (III) decreased linearly with the strength of nutrient solutions with or without N addition (p<0.01). Translocation efficiencies of both Cr species increased proportionally with the strength of N-containing nutrient solutions and decreased with the strength of N-free nutrient solutions. Results suggest that uptake and translocation mechanisms of Cr (VI) and Cr (III) are apparently different in hankow willows. The presence of easily available nitrogen and other nutrient elements in the nutrient solutions had a more pronounced influence on the uptake of Cr (III) than Cr (VI). Nitrogen availability and quantities in the ambient environment will affect the translocation of both Cr species and their distribution in willows in phytoremediation.

Scanning electron microscopy investigation of PMMA removal by laser irradiation (Er:YAG) in comparison with an ultrasonic system and curettage in hip joint revision arthroplasty.

PubMed

Birnbaum, Klaus; Gutknecht, Norbert

2010-07-01

The cement often left in the femur socket during hip joint revision arthroplasty is usually removed by curettage. Another method for removing the cement is to use an ultrasonic system, and yet another alternative may be to use a laser system. The aim of these investigations was to determine the pulse rate and pulse energy of the Er:YAG laser for sufficient cement ablation. We also compared the results obtained using the laser with those obtained using an ultrasonic device or curettage by histological and scanning electron microscopy (SEM) investigation of the border zone between the polymethyl methacrylate (PMMA) and unfixed specimens of femoral bone. Therefore we prepared 30 unfixed human femur stems after hip joint replacement and prepared ten sagittal sections from each femur stem (in total 300 sections). Of these 300 specimens, 180 were treated with the Er:YAG laser, 60 with the ultrasonic system and 60 by curettage. The high pulse energy of 500 mJ and a pulse rate of 4 Hz provided the highest PMMA ablation rate, although the boundary surface between PMMA and femoral bone was not as fine-grained as found in samples treated at 15 Hz and 250 mJ. However, the treatment time for the same cement ablation rate with the latter settings was twice that at 4 Hz and 500 mJ. Compared to the boundary surfaces treated with the ultrasonic device or curettage, the laser-treated samples had a more distinct undifferentiated boundary surface between PMMA and femoral bone. After development of the Er:YAG-laser to provide higher pulse energies, it may in the future be an additional efficient method for the removal of PMMA in revision arthroplasty. The Er:YAG laser should be combined with an endoscopic and a rinsing suction system so that PMMA can be removed from the femoral shaft under direct vision.

A home away from home: challenges and opportunities in engineering in vitro muscle satellite cell niches

PubMed Central

Cosgrove, Benjamin D.; Sacco, Alessandra; Gilbert, Penney M.; Blau, Helen M.

2009-01-01

Satellite cells are skeletal muscle stem cells with a principal role in postnatal skeletal muscle regeneration. Satellite cells, like many tissue-specific adult stem cells, reside in a quiescent state in an instructive, anatomically defined niche. The satellite cell niche constitutes a distinct membrane-enclosed compartment within the muscle fiber, containing a diversity of biochemical and biophysical signals that influence satellite cell function. A major limitation to the study and clinical utility of satellite cells is that upon removal from the muscle fiber and plating in traditional plastic tissue culture platforms, their muscle stem cell properties are rapidly lost. Clearly, the maintenance of stem cell function is critically dependent on in vivo niche signals, highlighting the need to create novel in vitro microenvironments that allow for the maintenance and propagation of satellite cells while retaining their potential to function as muscle stem cells. Here, we discuss how emerging biomaterials technologies offer great promise for engineering in vitro microenvironments to meet these challenges. In engineered biomaterials, signaling molecules can be presented in a manner that more closely mimics cell-cell and cell-matrix interactions and matrices can be fabricated with diverse rigidities that approximate in vivo tissues. The development of in vitro microenvironments in which niche features can be systematically modulated will be instrumental not only to future insights into muscle stem cell biology and therapeutic approaches to muscle diseases and muscle wasting with aging, but also will provide a paradigm for the analysis of numerous adult tissue-specific stem cells. PMID:19751902

Long Term Survivorship of a Severely Notched Femoral Stem after Replacing the Fractured Ceramic head with a Cobalt-Chromium Head

PubMed Central

Panagopoulos, Andreas; Tatani, Irini; Megas, Panagiotis

2016-01-01

Background: Although ceramic head fracture occurs infrequently today, in the event of a fracture, the resulting revision surgery can prove very challenging, since the ceramic particles lodge into the surrounding soft tissue and can cause rapid implant failure Case Presentation: A case of long term survivorship of a severed notched femoral stem after replacing the fractured femoral head with a cobalt-chromium one is reported in a 40-year old woman with hip dysplasia who underwent an uncomplicated total hip arthroplasty. The incident of ceramic femoral head fracture occurred 14 months postoperatively without reporting any significant trauma. Intraoperative findings at revision were a multifragmented femoral head and a damaged polyethylene insert along with diffuse metallosis and excessive wear of the cone of the stem. Both the stem and the acetabular component were stable. After removal of ceramic fragments, metallotic tissue excision and careful lavage of the joint, the inlay was replaced by a similar one and a cobalt-chromium femoral head was placed to the existing notched taper of the firmly incorporated stem. At the 13th year follow up examination, the patient had no pain, used no walking aids, and had normal activity with no signs of wearing or loosening in the plain x-rays. Conclusion: Despite current recommendations of using ceramic femoral heads in cases of fracture or to revise the severely damaged stems we were able to provide a long term survivorship up to 13 years postoperatively of a cobalt-chromium femoral head applied to a severe damaged stem. PMID:28217203

Long Term Survivorship of a Severely Notched Femoral Stem after Replacing the Fractured Ceramic head with a Cobalt-Chromium Head.

PubMed

Panagopoulos, Andreas; Tatani, Irini; Megas, Panagiotis

2016-01-01

Although ceramic head fracture occurs infrequently today, in the event of a fracture, the resulting revision surgery can prove very challenging, since the ceramic particles lodge into the surrounding soft tissue and can cause rapid implant failure. A case of long term survivorship of a severed notched femoral stem after replacing the fractured femoral head with a cobalt-chromium one is reported in a 40-year old woman with hip dysplasia who underwent an uncomplicated total hip arthroplasty. The incident of ceramic femoral head fracture occurred 14 months postoperatively without reporting any significant trauma. Intraoperative findings at revision were a multifragmented femoral head and a damaged polyethylene insert along with diffuse metallosis and excessive wear of the cone of the stem. Both the stem and the acetabular component were stable. After removal of ceramic fragments, metallotic tissue excision and careful lavage of the joint, the inlay was replaced by a similar one and a cobalt-chromium femoral head was placed to the existing notched taper of the firmly incorporated stem. At the 13 th year follow up examination, the patient had no pain, used no walking aids, and had normal activity with no signs of wearing or loosening in the plain x-rays. Despite current recommendations of using ceramic femoral heads in cases of fracture or to revise the severely damaged stems we were able to provide a long term survivorship up to 13 years postoperatively of a cobalt-chromium femoral head applied to a severe damaged stem.

Processing woody debris biomass for co-milling with pulverized coal

Treesearch

Dana Mitchell; Bob Rummer

2007-01-01

The USDA, Forest Service, Forest Products Lab funds several grants each year for the purpose of studying woody biomass utilization. One selected project proposed removing small diameter stems and unmerchantable woody material from National Forest lands and delivering it to a coal-fired power plant in Alabama for energy conversion. The Alabama Power Company...

Comparing Alternative Slashing Techniques on a Mixed Hardwood Forest: 2-Year Results

Treesearch

Donald G. Hodges; Richard M. Evans; Wayne K. Clatterbuck

2002-01-01

Regenerating commercially important species following the harvest of an existing mixed hardwood stand requires adequate advance regeneration of the desired species and control of competing vegetation. These objectives can be achieved by removing the noncommercial stems before or after harvesting. This study was designed to evaluate the efficacy of pre- and post...

Small-diameter trees used for chemithermomechanical pulps.

Treesearch

Gary C. Myers; R. James Barbour; Said M. AbuBakr

2003-01-01

To restore and maintain forest ecosystem health and function in the western interior of the United States, many small-diameter stems need to be removed from densely stocked stands. In general, these materials are underutilized. Information on the properties of these resources is needed to help forest managers understand when timber sales are a viable option to...

Preliminary results of sugar maple carbohydrate and growth response under vacuum and gravity sap extraction

Treesearch

Mark L. Isselhardt; Timothy D. Perkins; Abby K. van den Berg; Paul G. Schaberg

2016-01-01

Recent technological advancements have increased the amount of sugar-enriched sap that can be extracted from sugar maple (Acer saccharum). This pilot study quantified overall sugar removal and the impacts of vacuum (60 cm Hg) and gravity sap extraction on residual nonstructural carbohydrate (NSC) concentrations and on stem and twig growth. Vacuum...

Morphological characteristics of loblolly pine wood as related to specific gravity, growth rate and distance from pith

Treesearch

Charles W. McMillin

1968-01-01

Earlywood and latewood tracheid length and transverse cellular dimensions of wood removed from stems of loblolly pine (Pinus taeda L.) and factorially aegregated by specific gravity, rings from the pith, and growth rate were determined from sample chips. The independent relationships of each factor with fiber morphology are described.

Loading productivity of untrimmed and trimmed pulpwood

Treesearch

Jason Thompson; John Klepac; Dana Mitchell

2015-01-01

The increase in biomass usage for fuels and energy has required a re-examination of harvesting and transportation systems to efficiently deliver these products to market. Some biomass markets accept forest residues or whole trees (including stem wood, bark and needles) as a feedstock. Therefore, there is less need to remove limbs and tops or deconstruct the tree other...

Implementing and Sustaining Higher Education Service-Learning Initiatives: Revisiting Young et al.'s Organizational Tactics

ERIC Educational Resources Information Center

Bennett, Dawn; Sunderland, Naomi; Bartleet, Brydie-Leigh; Power, Anne

2016-01-01

Although the value of service-learning opportunities has long been aligned to student engagement, global citizenship, and employability, the rhetoric can be far removed from the reality of coordinating such activities within higher education. This article stems from arts-based service-learning initiatives with Indigenous communities in Australia.…

Surgical meshes coated with mesenchymal stem cells provide an anti-inflammatory environment by a M2 macrophage polarization.

PubMed

Blázquez, Rebeca; Sánchez-Margallo, Francisco Miguel; Álvarez, Verónica; Usón, Alejandra; Casado, Javier G

2016-02-01

Surgical meshes are widely used in clinics to reinforce soft tissue's defects, and to give support to prolapsed organs. However, the implantation of surgical meshes is commonly related with an inflammatory response being difficult to eradicate without removing the mesh. Here we hypothesize that the combined use of surgical meshes and mesenchymal stem cells (MSCs) could be a useful tool to reduce the inflammatory reaction secondary to mesh implantation. In vitro determinations of viability, metabolic activity and immunomodulation assays were performed on MSCs-coated meshes. Magnetic resonance imaging, evaluation by laparoscopic optical system and histology were performed for safety assessment. Finally, flow cytometry and qRT-PCR were used to elucidate the mechanism of action of MSCs-coated meshes. Our results demonstrate the feasibility to obtain MSCs-coated surgical meshes and their cryopreservability to be used as an 'off the shelf' product. These biological meshes fulfill the safety aspects as non-adverse effects were observed when compared to controls. Moreover, both in vitro and in vivo studies demonstrated that, local immunomodulation of implanted meshes is mediated by a macrophage polarization towards an anti-inflammatory phenotype. In conclusion, the combined usage of surgical meshes with MSCs fulfills the safety requirements for a future clinical application, providing an anti-inflammatory environment that could reduce the inflammatory processes commonly observed after surgical mesh implantation. Surgical meshes are medical devices widely used in clinics to resolve hernias and organs' prolapses, among other disorders. However, the implantation of surgical meshes is commonly related with an inflammatory response being difficult to eradicate without removing the mesh, causing pain and discomfort in the patient. Previously, the anti-inflammatory, immunomodulatory and pro-regenerative ability of mesenchymal stem cells (MSCs) have been described. To our knowledge, this is the first report where the anti-inflammatory and pro-regenerative ability of MSCs have been successfully applied in combination with surgical meshes, reducing the inflammatory processes commonly observed after mesh implantation. Moreover, our in vitro and in vivo results highlight the safety and efficacy of these bioactive meshes as a 'ready to use' medical product. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Breakdown of an ant-plant mutualism follows the loss of large herbivores from an African savanna.

PubMed

Palmer, Todd M; Stanton, Maureen L; Young, Truman P; Goheen, Jacob R; Pringle, Robert M; Karban, Richard

2008-01-11

Mutualisms are key components of biodiversity and ecosystem function, yet the forces maintaining them are poorly understood. We investigated the effects of removing large mammals on an ant-Acacia mutualism in an African savanna. Ten years of large-herbivore exclusion reduced the nectar and housing provided by plants to ants, increasing antagonistic behavior by a mutualistic ant associate and shifting competitive dominance within the plant-ant community from this nectar-dependent mutualist to an antagonistic species that does not depend on plant rewards. Trees occupied by this antagonist suffered increased attack by stem-boring beetles, grew more slowly, and experienced doubled mortality relative to trees occupied by the mutualistic ant. These results show that large mammals maintain cooperation within a widespread symbiosis and suggest complex cascading effects of megafaunal extinction.

Geotechnical Implications for the use of Alfalfa in Experimental Studies of Alluvial-Channel Morphology and Planform

NASA Astrophysics Data System (ADS)

Pollen, N.; Simon, A.

2006-12-01

Research on the interactions between vegetation and channel flow dynamics has shown that vegetation is an important control on river morphology and planform. Increased vegetation density is commonly linked to a decrease in bank erosion and lateral migration rates. Roots add to bank strength through the production of a reinforced soil-root matrix, and vegetation can also act to increase bank stability through its hydrological effects, including canopy interception, and removal of soil water through evapotranspiration. Flow dynamics are also affected by vegetation, with a number of studies showing a linkage between vegetation density and width- depth-velocity relations and bank roughness. To evaluate the effects of vegetation on channel morphology and planform, several experimental studies in flumes have used alfalfa sprouts (Medicago sativa) to seed the bed and banks of experimental channels. In such studies, the effects of vegetation are accounted for by qualitatively increasing the resistance of the bank material to lateral erosion. However, the material properties of alfalfa roots and stems, and the actual increase in resistance provided to the banks under different densities of alfalfa have thus far been ignored. To quantify this added erosion resistance, alfalfa sprouts were grown for 7 to 21 days, in sand with a d50 of 0.23 mm. At regular intervals, roots and stems were tested to measure tensile strength and forces required for pullout. Results of the tensile-strength measurements display the typical non-linear decrease of tensile strength (in MPa) with increasing root diameter but the curve is shifted to the left (weaker for a given diameter) of other riparian species. However, to calculate the increase in bank cohesion due to alfalfa roots, it is necessary to also account for the number of roots, and the distribution of different root diameters. The number of roots was calculated for a range of stem densities (0 to 10 stems/cm2), assuming a single, un-branching root per stem. Values for the additional cohesion provided by the alfalfa roots were calculated using the root- reinforcement model, RipRoot, producing values of 0 to 11.8 kPa. These results provide a means of quantifying the additional bank resistance provided to experimental channels under different stem/root densities. Cohesion values obtained in this way were successfully related to studies of braiding intensity published by others. The geometric properties of alfalfa scale up from experiments in flumes to approximate young trees on a floodplain. However, soil properties such as cohesion cannot be scaled. As such, the cohesion values due to roots calculated here represent the actual magnitude of reinforcement provided, rather than a scaled value.

Morphofunctional study of the therapeutic efficacy of human mesenchymal and neural stem cells in rats with diffuse brain injury.

PubMed

Tsyb, A F; Yuzhakov, V V; Roshal', L M; Sukhikh, G T; Konoplyannikov, A G; Sushkevich, G N; Yakovleva, N D; Ingel', I E; Bandurko, L N; Sevan'kaeva, L E; Mikhina, L N; Fomina, N K; Marei, M V; Semenova, Zh B; Konoplyannikova, O A; Kal'sina, S Sh; Lepekhina, L A; Semenkova, I V; Agaeva, E V; Shevchuk, A S; Pavlova, L N; Tokarev, O Yu; Karaseva, O V; Chernyshova, T A

2009-01-01

We studied the effect of transplantation of human stem cells from various tissues on reparative processes in the brain of rats with closed craniocerebral injury. Combined treatment with standard drugs and systemic administration of xenogeneic stem cells had a neuroprotective effect. The morphology of neurons rapidly returned to normal after administration of fetal neural stem cells. Fetal mesenchymal stem cells produced a prolonged effect on proliferative activity of progenitor cells in the subventricular zone of neurogenesis. Adult mesenchymal stem cells had a strong effect on recovery of the vascular bed in ischemic regions.

Bis-aptazyme sensors for hepatitis C virus replicase and helicase without blank signal

PubMed Central

Cho, Suhyung; Kim, Ji-Eun; Lee, Bo-Rahm; Kim, June-Hyung; Kim, Byung-Gee

2005-01-01

The fusion molecule (i.e. aptazyme) of aptamer and hammerhead ribozyme was developed as in situ sensor. Previously, the hammerhead ribozyme conjugated with aptamer through its stem II module showed a significant blank signal by self-cleavage. To reduce or remove its self-cleavage activity in the absence of target molecule, rational designs were attempted by reducing the binding affinity of the aptazyme to its RNA substrate, while maintaining the ribonuclease activity of the aptazyme. Interestingly, the bis-aptazymes which comprise the two aptamer-binding sites at both stem I and stem III of the hammerhead ribozyme showed very low blank signals, and their ratios of reaction rate constants, i.e. signal to noise ratios, were several tens to hundred times higher than those of the stem II-conjugated bis-aptazymes. The reduction in the blank signals seems to be caused by a higher dissociation constant between the main strand of the bis-aptazyme and its substrate arising from multi-point base-pairing of the bis-aptazymes. The bis-aptazymes for HCV replicase and helicase showed high selectivity against other proteins, and a linear relationship existed between their ribozyme activities and the target concentrations. In addition, a bis-aptazyme of dual functions was designed by inserting both aptamers for HCV replicase and helicase into the stem I and stem III of hammerhead ribozyme, respectively, and it also showed greater sensitivity and specificity for both proteins without blank signal. PMID:16314308

Extracellular matrix components direct porcine muscle stem cell behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilschut, Karlijn J.; Haagsman, Henk P.; Roelen, Bernard A.J., E-mail: b.a.j.roelen@uu.nl

2010-02-01

In muscle tissue, extracellular matrix proteins, together with the vasculature system, muscle-residence cells and muscle fibers, create the niche for muscle stem cells. The niche is important in controlling proliferation and directing differentiation of muscle stem cells to sustain muscle tissue. Mimicking the extracellular muscle environment improves tools exploring the behavior of primary muscle cells. Optimizing cell culture conditions to maintain muscle commitment is important in stem cell-based studies concerning toxicology screening, ex vivo skeletal muscle tissue engineering and in the enhancement of clinical efficiency. We used the muscle extracellular matrix proteins collagen type I, fibronectin, laminin, and also gelatinmore » and Matrigel as surface coatings of tissue culture plastic to resemble the muscle extracellular matrix. Several important factors that determine myogenic commitment of the primary muscle cells were characterized by quantitative real-time RT-PCR and immunofluorescence. Adhesion of high PAX7 expressing satellite cells was improved if the cells were cultured on fibronectin or laminin coatings. Cells cultured on Matrigel and laminin coatings showed dominant integrin expression levels and exhibited an activated Wnt pathway. Under these conditions both stem cell proliferation and myogenic differentiation capacity were superior if compared to cells cultured on collagen type I, fibronectin and gelatin. In conclusion, Matrigel and laminin are the preferred coatings to sustain the proliferation and myogenic differentiation capacity of the primary porcine muscle stem cells, when cells are removed from their natural environment for in vitro culture.« less

Generation of functional hepatocytes from human spermatogonial stem cells.

PubMed

Chen, Zheng; Sun, Min; Yuan, Qingqing; Niu, Minghui; Yao, Chencheng; Hou, Jingmei; Wang, Hong; Wen, Liping; Liu, Yun; Li, Zheng; He, Zuping

2016-02-23

To generate functional human hepatocytes from stem cells and/or extra-hepatic tissues could provide an important source of cells for treating liver diseases. Spermatogonial stem cells (SSCs) have an unlimited plasticity since they can dedifferentiate and transdifferentiate to other cell lineages. However, generation of mature and functional hepatocytes from human SSCs has not yet been achieved. Here we have for the first time reported direct transdifferentiation of human SSCs to mature and functional hepatocytes by three-step induction using the defined condition medium. Human SSCs were first transdifferentiated to hepatic stem cells, as evidenced by their morphology and biopotential nature of co-expressing hepatocyte and cholangiocyte markers but not hallmarks for embryonic stem cells. Hepatic stem cells were further induced to differentiate into mature hepatocytes identified by their morphological traits and strong expression of CK8, CK18, ALB, AAT, TF, TAT, and cytochrome enzymes rather than CK7 or CK19. Significantly, mature hepatocytes derived from human SSCs assumed functional attributes of human hepatocytes, because they could produce albumin, remove ammonia, and uptake and release indocyanine green. Moreover, expression of β-CATENIN, HNF4A, FOXA1 and GATA4 was upregulated during the transdifferentiation of human SSCs to mature hepatocytes. Collectively, human SSCs could directly transdifferentiate to mature and functional hepatocytes. This study could offer an invaluable source of human hepatocytes for curing liver disorders and drug toxicology screening and provide novel insights into mechanisms underlying human liver regeneration.

Generation of functional hepatocytes from human spermatogonial stem cells

PubMed Central

Chen, Zheng; Sun, Min; Yuan, Qingqing; Niu, Minghui; Yao, Chencheng; Hou, Jingmei; Wang, Hong; Wen, Liping; Liu, Yun; Li, Zheng; He, Zuping

2016-01-01

To generate functional human hepatocytes from stem cells and/or extra-hepatic tissues could provide an important source of cells for treating liver diseases. Spermatogonial stem cells (SSCs) have an unlimited plasticity since they can dedifferentiate and transdifferentiate to other cell lineages. However, generation of mature and functional hepatocytes from human SSCs has not yet been achieved. Here we have for the first time reported direct transdifferentiation of human SSCs to mature and functional hepatocytes by three-step induction using the defined condition medium. Human SSCs were first transdifferentiated to hepatic stem cells, as evidenced by their morphology and biopotential nature of co-expressing hepatocyte and cholangiocyte markers but not hallmarks for embryonic stem cells. Hepatic stem cells were further induced to differentiate into mature hepatocytes identified by their morphological traits and strong expression of CK8, CK18, ALB, AAT, TF, TAT, and cytochrome enzymes rather than CK7 or CK19. Significantly, mature hepatocytes derived from human SSCs assumed functional attributes of human hepatocytes, because they could produce albumin, remove ammonia, and uptake and release indocyanine green. Moreover, expression of β-CATENIN, HNF4A, FOXA1 and GATA4 was upregulated during the transdifferentiation of human SSCs to mature hepatocytes. Collectively, human SSCs could directly transdifferentiate to mature and functional hepatocytes. This study could offer an invaluable source of human hepatocytes for curing liver disorders and drug toxicology screening and provide novel insights into mechanisms underlying human liver regeneration. PMID:26840458

Concise review: Insights from normal bone remodeling and stem cell-based therapies for bone repair.

PubMed

Khosla, Sundeep; Westendorf, Jennifer J; Mödder, Ulrike I

2010-12-01

There is growing interest in the use of mesenchymal stem cells for bone repair. As a major reason for normal bone remodeling is the removal of fatigue microcracks, advances in our understanding of this process may inform approaches to enhance fracture healing. Increasing evidence now indicates that physiological bone remodeling occurs in close proximity to blood vessels and that these vessels carry perivascular stem cells that differentiate into osteoblasts. Similarly, fracture healing is critically dependent on the ingrowth of blood vessels not only for a nutrient supply but also for the influx of osteoblasts. A number of animal and human studies have now shown the potential benefit of bone marrow-derived mesenchymal stem cells in enhancing bone repair. However, as in other tissues, the question of whether these cells improve fracture healing directly by differentiating into osteoblasts or indirectly by secreting paracrine factors that recruit blood vessels and the accompanying perivascular stem cells remains a major unresolved issue. Moreover, CD34+ cells, which are enriched for endothelial/hematopoietic cells, have also shown efficacy in various bone repair models, at least in part due to the induction of angiogenesis and recruitment of host progenitor cells. Thus, mesenchymal and nonmesenchymal stem/progenitor cells are attractive options for bone repair. It is possible that they contribute directly to bone repair, but it is also likely that they express paracrine factors in the appropriate amounts and combinations that promote and sustain the healing process.

Stem girdling evidences a trade-off between cambial activity and sprouting and dramatically reduces plant transpiration due to feedback inhibition of photosynthesis and hormone signaling

PubMed Central

López, Rosana; Brossa, Ricard; Gil, Luis; Pita, Pilar

2015-01-01

The photosynthesis source–sink relationship in young Pinus canariensis seedlings was modified by stem girdling to investigate sprouting and cambial activity, feedback inhibition of photosynthesis, and stem and root hydraulic capacity. Removal of bark tissue showed a trade-off between sprouting and diameter growth. Above the girdle, growth was accelerated but the number of sprouts was almost negligible, whereas below the girdle the response was reversed. Girdling resulted in a sharp decrease in whole plant transpiration and root hydraulic conductance. The reduction of leaf area after girdling was strengthened by the high levels of abscisic acid found in buds which pointed to stronger bud dormancy, preventing a new needle flush. Accumulation of sugars in leaves led to a coordinated reduction in net photosynthesis (AN) and stomatal conductance (gS) in the short term, but later (gS below 0.07 mol m-2 s-1) AN decreased faster. The decrease in maximal efficiency of photosystem II (FV/FM) and the operating quantum efficiency of photosystem II (ΦPSII) in girdled plants could suggest photoprotection of leaves, as shown by the vigorous recovery of AN and ΦPSII after reconnection of the phloem. Stem girdling did not affect xylem embolism but increased stem hydraulic conductance above the girdle. This study shows that stem girdling affects not only the carbon balance, but also the water status of the plant. PMID:25972884

Stem girdling evidences a trade-off between cambial activity and sprouting and dramatically reduces plant transpiration due to feedback inhibition of photosynthesis and hormone signaling.

PubMed

López, Rosana; Brossa, Ricard; Gil, Luis; Pita, Pilar

2015-01-01

The photosynthesis source-sink relationship in young Pinus canariensis seedlings was modified by stem girdling to investigate sprouting and cambial activity, feedback inhibition of photosynthesis, and stem and root hydraulic capacity. Removal of bark tissue showed a trade-off between sprouting and diameter growth. Above the girdle, growth was accelerated but the number of sprouts was almost negligible, whereas below the girdle the response was reversed. Girdling resulted in a sharp decrease in whole plant transpiration and root hydraulic conductance. The reduction of leaf area after girdling was strengthened by the high levels of abscisic acid found in buds which pointed to stronger bud dormancy, preventing a new needle flush. Accumulation of sugars in leaves led to a coordinated reduction in net photosynthesis (AN) and stomatal conductance (gS) in the short term, but later (gS below 0.07 mol m(-2) s(-1)) AN decreased faster. The decrease in maximal efficiency of photosystem II (FV/FM) and the operating quantum efficiency of photosystem II (ΦPSII) in girdled plants could suggest photoprotection of leaves, as shown by the vigorous recovery of AN and ΦPSII after reconnection of the phloem. Stem girdling did not affect xylem embolism but increased stem hydraulic conductance above the girdle. This study shows that stem girdling affects not only the carbon balance, but also the water status of the plant.

Effects of herbicides on Behr's metalmark butterfly, a surrogate species for the endangered butterfly, Lange's metalmark.

PubMed

Stark, John D; Chen, Xue Dong; Johnson, Catherine S

2012-05-01

Lange's metalmark butterfly, Apodemia mormo langei Comstock, is in danger of extinction due to loss of habitat caused by invasive exotic plants which are eliminating its food, naked stem buckwheat. Herbicides are being used to remove invasive weeds from the dunes; however, little is known about the potential effects of herbicides on butterflies. To address this concern we evaluated potential toxic effects of three herbicides on Behr's metalmark, a close relative of Lange's metalmark. First instars were exposed to recommended field rates of triclopyr, sethoxydim, and imazapyr. Life history parameters were recorded after exposure. These herbicides reduced the number of adults that emerged from pupation (24-36%). Each herbicide has a different mode of action. Therefore, we speculate that effects are due to inert ingredients or indirect effects on food plant quality. If these herbicides act the same in A. mormo langei, they may contribute to the decline of this species. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of nitrogen fertilization and fungicides on Botryosphaeria stem blight lesion development on detached stems

USDA-ARS?s Scientific Manuscript database

: Botryosphaeria stem blight is a destructive disease of blueberries that has not been well managed with fungicides. Field observations showed that stem blight is more severe on vigorously growing plants than on slower growing plants. Detached stem assays were used to compare the effect of fertil...

HCN4-Overexpressing Mouse Embryonic Stem Cell-Derived Cardiomyocytes Generate a New Rapid Rhythm in Rats with Bradycardia.

PubMed

Saito, Yukihiro; Nakamura, Kazufumi; Yoshida, Masashi; Sugiyama, Hiroki; Takano, Makoto; Nagase, Satoshi; Morita, Hiroshi; Kusano, Kengo F; Ito, Hiroshi

2018-05-30

A biological pacemaker is expected to solve the persisting problems of an artificial cardiac pacemaker including short battery life, lead breaks, infection, and electromagnetic interference. We previously reported HCN4 overexpression enhances pacemaking ability of mouse embryonic stem cell-derived cardiomyocytes (mESC-CMs) in vitro. However, the effect of these cells on bradycardia in vivo has remained unclear. Therefore, we transplanted HCN4-overexpressing mESC-CMs into bradycardia model animals and investigated whether they could function as a biological pacemaker. The rabbit Hcn4 gene was transfected into mouse embryonic stem cells and induced HCN4-overexpressing mESC-CMs. Non-cardiomyocytes were removed under serum/glucose-free and lactate-supplemented conditions. Cardiac balls containing 5 × 10 3 mESC-CMs were made by using the hanging drop method. One hundred cardiac balls were injected into the left ventricular free wall of complete atrioventricular block (CAVB) model rats. Heart beats were evaluated using an implantable telemetry system 7 to 30 days after cell transplantation. The result showed that ectopic ventricular beats that were faster than the intrinsic escape rhythm were often observed in CAVB model rats transplanted with HCN4-overexpressing mESC-CMs. On the other hand, the rats transplanted with non-overexpressing mESC-CMs showed sporadic single premature ventricular contraction but not sustained ectopic ventricular rhythms. These results indicated that HCN4-overexpressing mESC-CMs produce rapid ectopic ventricular rhythms as a biological pacemaker.

Inactivation of an integrated antibiotic resistance gene in mammalian cells to re-enable antibiotic selection.

PubMed

Ni, Peiling; Zhang, Qian; Chen, Haixia; Chen, Lingyi

2014-01-01

Removing an antibiotic resistance gene allows the same antibiotic to be re-used in the next round of genetic manipulation. Here we applied the CRISPR/Cas system to disrupt the puromycin resistance gene in an engineered mouse embryonic stem cell line and then re-used puromycin selection in the resulting cells to establish stable reporter cell lines. With the CRISPR/Cas system, pre-engineered sequences, such as loxP or FRT, are not required. Thus, this technique can be used to disrupt antibiotic resistance genes that cannot be removed by the Cre-loxP and Flp-FRT systems.

Hypoxia enhances the protective effects of placenta-derived mesenchymal stem cells against scar formation through hypoxia-inducible factor-1α.

PubMed

Du, Lili; Lv, Runxiao; Yang, Xiaoyi; Cheng, Shaohang; Xu, Jing; Ma, Tingxian

2016-06-01

To explore the effect of placenta-derived mesenchymal stem cells on scar formation as well as the underlying mechanism. The isolated placenta-derived mesenchymal stem cells from mice were distributed in the wounded areas of scalded mouse models, attenuated inflammatory responses and decreased the deposition of collagens, thus performing a beneficial effect against scar formation. Hypoxia enhanced the protective effect of placenta-derived mesenchymal stem cells and hypoxia-inducible factor-1α was involved in the protective effect of placenta-derived mesenchymal stem cells in hypoxic condition. Hypoxia enhanced the protective effect of placenta-derived mesenchymal stem cells through hypoxia-inducible factor-1α and PMSCs may have a potential application in the treatment of wound.

Microsurgical management of a complicated aneurysmal endovascular embolisation with GDC coil: a case report.

PubMed

Pogády, P; Mustafa, H; Wies, W; Lungenschmid, K; Wurm, G; Tomancok, B; Holl, K; Fischer, J

1998-01-01

We present a case involving a microsurgical approach to solving the problem of a medial cerebral artery (MCA) occlusion occurring after GDC coiling of an internal cerebral artery (ICA) bifurcation aneurysm in a 40 year old woman. We describe the clinical course of the case and discuss technical possibilities and risks of clipping a coiled aneurysm. One key to success is awareness of changes in the aneurysm's properties after coiling. With loss of elasticity the aneurysm had the effect of a tumor fixed on the vessel. The apposition of the aneurysm to the wall of the vessel, as well as the aneurysm's rigidity and increase of intracranial pressure after subarachnoideal hemorrhage (SAH), may lead to occlusion of the vessel. In cases of an mandatory operation due to the occlusion of a main arterial stem after coiling, it is primarily crucial to perforate the aneurysm's fundus, remove the coils, and, finally, to clip the slack neck of the aneurysm. An attempt to precisely prepare and clip the aneurysmal neck without removing the coils could result in the rupture of the aneurysm's neck.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halvorson, J.J.; Bolton, H. Jr.; Smith, J.L.

Artemisia tridentata is a prominent shrub of cool deserts that affects the soil in which it grows. We sampled adjacent burned and unburned sites to see if resource islands persisted in locations where shrubs had been removed by fire. The concentrations of soil variables near the location of burned Artemisia tridentata were smaller than under live Artemisia tridentata and did not vary as much with distance away from the plant axis. However, the patterns of soil variables in these remnant resource islands were still substantial. Significantly higher concentrations of total N and soil microbial C, and significantly higher electrical conductivitymore » were observed at the location of a burned Artemisia tridentata stem than at distances further away. The differences between burned and unburned soil were greatest in samples collected near the plant. In contrast, samples of burned or unburned soil were not distinguishable from each other at locations greater than about 50 cm away from a live Artemisia tridentata axis or a burned stump indicating that the resource island effect was most affected by removal of the plant and not by the fire.« less

Canine and Equine Mesenchymal Stem Cells Grown in Serum Free Media Have Altered Immunophenotype.

PubMed

Clark, Kaitlin C; Kol, Amir; Shahbenderian, Salpi; Granick, Jennifer L; Walker, Naomi J; Borjesson, Dori L

2016-04-01

Mesenchymal stem cell (MSC) therapy is being increasingly used to treat dogs and horses with naturally-occurring diseases. However these animals also serve as critical large animal models for ongoing translation of cell therapy products to the human market. MSC manufacture for clinical use mandates improvement in cell culture systems to meet demands for higher MSC numbers and removal of xeno-proteins (i.e. fetal bovine serum, FBS). While serum-free media (SFM) is commercially available, its affects on MSC phenotype and immunomodulatory functions are not fully known. The objective of this study was to determine if specific MSC culture conditions, MSC expansion in HYPERFlasks® or MSC expansion in a commercially available SFM, would alter MSC proliferation, phenotype or immunomodulatory properties in vitro. MSCs cultured in HYPERFlasks® were similar in phenotype, proliferative capacity and immunomodulatory functions to MSCs grown in standard flasks however MSC yield was markedly increased. HYPERFlasks® therefore provide a viable option to generate greater cell numbers in a streamlined manner. Canine and equine MSCs expanded in SFM displayed similar proliferation, surface phenotype and inhibitory effect on lymphocyte proliferation in vitro. However, MSCs cultured in the absence of FBS secreted significantly less PGE2, and were significantly less able to inhibit IFNγ secretion by activated T-cells. Immunomodulatory functions altered by expansion in SFM were species dependent. Unlike equine MSCs, in canine adipose-derived MSCs, the inhibition of lymphocyte proliferation was not principally modulated by PGE2. The removal of FBS from both canine and equine MSC culture systems resulted in altered immunomodulatory properties in vitro and warrants further investigation prior to moving towards FBS-free culture conditions.

Decellularized Cartilage May Be a Chondroinductive Material for Osteochondral Tissue Engineering

PubMed Central

Sutherland, Amanda J.; Beck, Emily C.; Dennis, S. Connor; Converse, Gabriel L.; Hopkins, Richard A.; Berkland, Cory J.; Detamore, Michael S.

2015-01-01

Extracellular matrix (ECM)-based materials are attractive for regenerative medicine in their ability to potentially aid in stem cell recruitment, infiltration, and differentiation without added biological factors. In musculoskeletal tissue engineering, demineralized bone matrix is widely used, but recently cartilage matrix has been attracting attention as a potentially chondroinductive material. The aim of this study was thus to establish a chemical decellularization method for use with articular cartilage to quantify removal of cells and analyze the cartilage biochemical content at various stages during the decellularization process, which included a physically devitalization step. To study the cellular response to the cartilage matrix, rat bone marrow-derived mesenchymal stem cells (rBMSCs) were cultured in cell pellets containing cells only (control), chondrogenic differentiation medium (TGF-β), chemically decellularized cartilage particles (DCC), or physically devitalized cartilage particles (DVC). The chemical decellularization process removed the vast majority of DNA and about half of the glycosaminoglycans (GAG) within the matrix, but had no significant effect on the amount of hydroxyproline. Most notably, the DCC group significantly outperformed TGF-β in chondroinduction of rBMSCs, with collagen II gene expression an order of magnitude or more higher. While DVC did not exhibit a chondrogenic response to the extent that DCC did, DVC had a greater down regulation of collagen I, collagen X and Runx2. A new protocol has been introduced for cartilage devitalization and decellularization in the current study, with evidence of chondroinductivity. Such bioactivity along with providing the ‘raw material’ building blocks of regenerating cartilage may suggest a promising role for DCC in biomaterials that rely on recruiting endogenous cell recruitment and differentiation for cartilage regeneration. PMID:25965981

Regulatory variants of FOXG1 in the context of its topological domain organisation.

PubMed

Mehrjouy, Mana M; Fonseca, Ana Carolina S; Ehmke, Nadja; Paskulin, Giorgio; Novelli, Antonio; Benedicenti, Francesco; Mencarelli, Maria Antonietta; Renieri, Alessandra; Busa, Tiffany; Missirian, Chantal; Hansen, Claus; Abe, Kikue Terada; Speck-Martins, Carlos Eduardo; Vianna-Morgante, Angela M; Bak, Mads; Tommerup, Niels

2018-02-01

FOXG1 syndrome is caused by FOXG1 intragenic point mutations, or by long-range position effects (LRPE) of intergenic structural variants. However, the size of the FOXG1 regulatory landscape is uncertain, because the associated topologically associating domain (TAD) in fibroblasts is split into two domains in embryonic stem cells (hESC). Indeed, it has been suggested that the pathogenetic mechanism of deletions that remove the stem-cell-specific TAD boundary may be enhancer adoption due to ectopic activity of enhancer(s) located in the distal hESC-TAD. Herein we map three de novo translocation breakpoints to the proximal regulatory domain of FOXG1. The classical FOXG1 syndrome in these and in other translocation patients, and in a patient with an intergenic deletion that removes the hESC-specific TAD boundary, do not support the hypothesised enhancer adoption as a main contributor to the FOXG1 syndrome. Also, virtual 4 C and HiC-interaction data suggest that the hESC-specific TAD boundary may not be critical for FOXG1 regulation in a majority of human cells and tissues, including brain tissues and a neuronal progenitor cell line. Our data support the importance of a critical regulatory region (SRO) proximal to the hESC-specific TAD boundary. We further narrow this critical region by a deletion distal to the hESC-specific boundary, associated with a milder clinical phenotype. The distance from FOXG1 to the SRO ( > 500 kb) highlight a limitation of ENCODE DNase hypersensitivity data for functional prediction of LRPE. Moreover, the SRO has little overlap with a cluster of frequently associating regions (FIREs) located in the proximal hESC-TAD.

Effect of aging on stem cells

PubMed Central

Ahmed, Abu Shufian Ishtiaq; Sheng, Matilda HC; Wasnik, Samiksha; Baylink, David J; Lau, Kin-Hing William

2017-01-01

Pluripotent stem cells have the remarkable self-renewal ability and are capable of differentiating into multiple diverse cells. There is increasing evidence that the aging process can have adverse effects on stem cells. As stem cells age, their renewal ability deteriorates and their ability to differentiate into the various cell types is altered. Accordingly, it is suggested aging-induced deterioration of stem cell functions may play a key role in the pathophysiology of the various aging-associated disorders. Understanding the role of the aging process in deterioration of stem cell function is crucial, not only in understanding the pathophysiology of aging-associated disorders, but also in future development of novel effective stem cell-based therapies to treat aging-associated diseases. This review article first focuses on the basis of the various aging disease-related stem cell dysfunction. It then addresses the several concepts on the potential mechanism that causes aging-related stem cell dysfunction. It also briefly discusses the current potential therapies under development for aging-associated stem cell defects. PMID:28261550

Tree water storage and its diurnal dynamics related to sap flow and changes in stem volume in old-growth Douglas-fir trees.

PubMed

Cermák, Jan; Kucera, Jiri; Bauerle, William L; Phillips, Nathan; Hinckley, Thomas M

2007-02-01

Diurnal and seasonal tree water storage was studied in three large Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees at the Wind River Canopy Crane Research site. Changes in water storage were based on measurements of sap flow and changes in stem volume and tissue water content at different heights in the stem and branches. We measured sap flow by two variants of the heat balance method (with internal heating in stems and external heating in branches), stem volume with electronic dendrometers, and tissue water content gravimetrically. Water storage was calculated from the differences in diurnal courses of sap flow at different heights and their integration. Old-growth Douglas-fir trees contained large amounts of free water: stem sapwood was the most important storage site, followed by stem phloem, branch sapwood, branch phloem and needles. There were significant time shifts (minutes to hours) between sap flow measured at different positions within the transport system (i.e., stem base to shoot tip), suggesting a highly elastic transport system. On selected fine days between late July and early October, when daily transpiration ranged from 150 to 300 liters, the quantity of stored water used daily ranged from 25 to 55 liters, i.e., about 20% of daily total sap flow. The greatest amount of this stored water came from the lower stem; however, proportionally more water was removed from the upper parts of the tree relative to their water storage capacity. In addition to lags in sap flow from one point in the hydrolic pathway to another, the withdrawal and replacement of stored water was reflected in changes in stem volume. When point-to-point lags in sap flow (minutes to hours near the top and stem base, respectively) were considered, there was a strong linear relationship between stem volume changes and transpiration. Volume changes of the whole tree were small (equivalent to 14% of the total daily use of stored water) indicating that most stored water came from the stem and from its inelastic (sapwood) tissues. Whole tree transpiration can be maintained with stored water for about a week, but it can be maintained with stored water from the upper crown alone for no more than a few hours.

The influence of stem initiative programs for middle and high school students on female STEM college majors

NASA Astrophysics Data System (ADS)

McCaslin, Stephanie D.

The areas of Science, Technology, Engineering, and Mathematics have long been overrepresented by men. In the workforce, more men work in these fields than women, and in school, more male students select majors in Science, Technology, Engineering, and Mathematics (STEM) than female students. Research has indicated that female students represent less than a third of college students selecting STEM majors. Several recommendations have been made by prominent educational organizations, such as the American Association of University Women (AAUW), including promoting these subjects to female students through STEM initiatives that are innovative and expose female students to careers in these areas. This qualitative research study sought to analyze the effectiveness of these initiatives by determining what factors are considered when a female student selects a STEM field of study at the college level and to examine how these students perceived the effectiveness of the STEM initiatives in which they participated. A series of interviews were conducted with female college students with declared majors in STEM fields who had participated in STEM initiatives in the state of Maryland. After analysis of the data collected, it was determined that STEM initiatives are not necessarily effective in increasing the number of women who enroll in STEM programs at the college level, however, they are effective in encouraging female students who are already interested in STEM. Female students who participated in these STEM initiatives more frequently were more likely to have a better understanding of STEM options, and were also more likely to complete STEM college degrees in less time than those who did not participate frequently in STEM initiatives.

Effects of Implementing STEM-I Project-Based Learning Activities for Female High School Students

ERIC Educational Resources Information Center

Lou, Shi-Jer; Tsai, Huei-Yin; Tseng, Kuo-Hung; Shih, Ru-Chu

2014-01-01

This study aims to explore the application of STEM-I (STEM-Imagination) project-based learning activities and its effects on the effectiveness, processes, and characteristics of STEM integrative knowledge learning and imagination development for female high school students. A total of 72 female high school students were divided into 18 teams.…

77 FR 60237 - Endangered and Threatened Wildlife and Plants; Removal of the Valley Elderberry Longhorn Beetle...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-02

... coloration, where males of the listed subspecies have predominantly red elytra with four dark spots, whereas... groups, on the leaves or stems of living elderberry shrubs (Barr 1991, p. 4). The larvae hatch in a few... occurrences do not necessarily indicate the number and size of interbreeding populations (defined as groups of...

Transport of intercepted snow from trees during snow storms

Treesearch

David H. Miller

1966-01-01

Five principal processes by which intercepted snow in trees is removed during snow storms are described and evaluated as far as data permit: vapor flux from melt water, vapor flux from bodies of snow, stem flow and dripping of melt water, sliding of bodies of intercepted snow from branches, and wind erosion and transport of intercepted snow. Further research is...

77 FR 13626 - Notice of Inventory Completion: Maxey Museum, Whitman College, Walla Walla, WA

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-07

... remains representing, at minimum, six individuals were removed from an unknown location near the..., consisting of: 3 envelopes with writing; 1 lot of small pieces of leather belt or harness; 1 lot of charcoal pieces; 3 metal bells; 1 pipe stem; 1 piece of iron; 1 envelope with no writing; 1 chert flake; 1 lot of...

Sprout Singling in North Alabama Hardwoods

Treesearch

Kozma Naka; Philip G. Cannon

2004-01-01

Many commercial hardwood species grow quite well in northern Alabama and most regenerate by stump sprouts after harvest. The number of sprouts on a stump depends on several factors such as species and stump size. To determine if the practice of singling (removing all but the single best sprout from a stump) might be a means of accelerating the growth rate of one stem...

Cost and utilization of above ground biomass in thinning systems

Treesearch

Billy Watson; Bryce Stokes

1994-01-01

The cost and utilization were compared for a thinning operation removing the stems as roundwood with a flail chipper operation. The flail chipper operation recovered an additional 4.2 tons of acceptable chips per acre which resulted in a higher return to the site. There was little difference in the cost of acceptable chips delivered to the digester between the two...

ION PRODUCING MECHANISM (CHARGE CUPS)

DOEpatents

Brobeck, W.W.

1959-04-21

The problems of confining a charge material in a calutron and uniformly distributing heat to the charge is described. The charge is held in a cup of thermally conductive material removably disposed within the charge chamber of the ion source block. A central thermally conducting stem is incorporated within the cup for conducting heat to the central portion of the charge contained within the cup.

A strategic assessment of forest biomass and fuel reduction treatments in Western States

Treesearch

USDA Forest Service; Bob Rummer; Jeff Prestemon; Dennis May; Pat Miles; John Vissage; Ron McRoberts; Greg Liknes; Wayne D. Shepperd; Dennis Ferguson; William Elliot; Sue Miller; Steve Reutebuch; Jamie Barbour; Jeremy Fried; Bryce Stokes; Edward Bilek; Ken Skog

2005-01-01

This assessment characterizes, at a regional scale, forest biomass that can potentially be removed to implement the fuel reduction and ecosystem restoration objectives of the National Fire Plan for the Western United States. The assessment area covers forests on both public and private ownerships in the region and describes all standing tree volume including stems,...

High Glutathione and Glutathione Peroxidase-2 Levels Mediate Cell-Type-Specific DNA Damage Protection in Human Induced Pluripotent Stem Cells

PubMed Central

Dannenmann, Benjamin; Lehle, Simon; Hildebrand, Dominic G.; Kübler, Ayline; Grondona, Paula; Schmid, Vera; Holzer, Katharina; Fröschl, Mirjam; Essmann, Frank; Rothfuss, Oliver; Schulze-Osthoff, Klaus

2015-01-01

Summary Pluripotent stem cells must strictly maintain genomic integrity to prevent transmission of mutations. In human induced pluripotent stem cells (iPSCs), we found that genome surveillance is achieved via two ways, namely, a hypersensitivity to apoptosis and a very low accumulation of DNA lesions. The low apoptosis threshold was mediated by constitutive p53 expression and a marked upregulation of proapoptotic p53 target genes of the BCL-2 family, ensuring the efficient iPSC removal upon genotoxic insults. Intriguingly, despite the elevated apoptosis sensitivity, both mitochondrial and nuclear DNA lesions induced by genotoxins were less frequent in iPSCs compared to fibroblasts. Gene profiling identified that mRNA expression of several antioxidant proteins was considerably upregulated in iPSCs. Knockdown of glutathione peroxidase-2 and depletion of glutathione impaired protection against DNA lesions. Thus, iPSCs ensure genomic integrity through enhanced apoptosis induction and increased antioxidant defense, contributing to protection against DNA damage. PMID:25937369

Periodontal Ligament Stem Cell-Mediated Treatment for Periodontitis in Miniature Swine

PubMed Central

Liu, Yi; Zheng, Ying; Ding, Gang; Fang, Dianji; Zhang, Chunmei; Bartold, Peter Mark; Gronthos, Stan; Shi, Songtao; Wang, Songlin

2009-01-01

Periodontitis is a periodontal tissue infectious disease and the most common cause for tooth loss in adults. It has been linked to many systemic disorders, such as coronary artery disease, stroke, and diabetes. At present, there is no ideal therapeutic approach to cure periodontitis and achieve optimal periodontal tissue regeneration. In this study, we explored the potential of using autologous periodontal ligament stem cells (PDLSCs) to treat periodontal defects in a porcine model of periodontitis. The periodontal lesion was generated in the first molars area of miniature pigs by the surgical removal of bone and subsequent silk ligament suture around the cervical portion of the tooth. Autologous PDLSCs were obtained from extracted teeth of the miniature pigs and then expanded ex vivo to enrich PDLSC numbers. When transplanted into the surgically created periodontal defect areas, PDLSCs were capable of regenerating periodontal tissues, leading to a favorable treatment for periodontitis. This study demonstrates the feasibility of using stem cell-mediated tissue engineering to treat periodontal diseases. PMID:18238856

PSA-NCAM-Negative Neural Crest Cells Emerging during Neural Induction of Pluripotent Stem Cells Cause Mesodermal Tumors and Unwanted Grafts

PubMed Central

Lee, Dongjin R.; Yoo, Jeong-Eun; Lee, Jae Souk; Park, Sanghyun; Lee, Junwon; Park, Chul-Yong; Ji, Eunhyun; Kim, Han-Soo; Hwang, Dong-Youn; Kim, Dae-Sung; Kim, Dong-Wook

2015-01-01

Summary Tumorigenic potential of human pluripotent stem cells (hPSCs) is an important issue in clinical applications. Despite many efforts, PSC-derived neural precursor cells (NPCs) have repeatedly induced tumors in animal models even though pluripotent cells were not detected. We found that polysialic acid-neural cell adhesion molecule (PSA-NCAM)− cells among the early NPCs caused tumors, whereas PSA-NCAM+ cells were nontumorigenic. Molecular profiling, global gene analysis, and multilineage differentiation of PSA-NCAM− cells confirm that they are multipotent neural crest stem cells (NCSCs) that could differentiate into both ectodermal and mesodermal lineages. Transplantation of PSA-NCAM− cells in a gradient manner mixed with PSA-NCAM+ cells proportionally increased mesodermal tumor formation and unwanted grafts such as PERIPHERIN+ cells or pigmented cells in the rat brain. Therefore, we suggest that NCSCs are a critical target for tumor prevention in hPSC-derived NPCs, and removal of PSA-NCAM− cells eliminates the tumorigenic potential originating from NCSCs after transplantation. PMID:25937368

Separation of human bone marrow by counterflow centrifugation monitored by DNA-flowcytometry.

PubMed

de Witte, T; Plas, A; Koekman, E; Blankenborg, G; Salden, M; Wessels, J; Haanen, C

1984-10-01

Human bone marrow was fractionated by counterflow centrifugation into 16 fractions with increasing cell size. Three distinct subpopulations could be recognized: small lymphocytic cells, medium-sized nucleated erythroid cells and large myeloid elements. DNA-flowcytometry and 3H-thymidine uptake showed that within the erythroid and myeloid cell populations counterflow centrifugation separates each population according to the cell cycle phase. Hypotonic treatment of bone marrow for removal of the erythroid nucleated cells resulted in a complete abrogation of the proliferating erythroid cell population. Counterflow centrifugation also separates the small non-proliferating myeloid and erythroid committed stem cells from the larger proliferating stem cells. It appeared feasible to separate the small lymphocytic cells from the majority of BFU-E and CFU-GM, due to the larger size of the proliferating normoblasts and the committed progenitor cells. Elimination of the mature lymphocytes from the haematopoietic stem cells by counterflow centrifugation may offer an alternative approach to the prevention of graft versus host disease (GvHD).

Brief Reports: Nfix Promotes Survival of Immature Hematopoietic Cells via Regulation of c-Mpl.

PubMed

Hall, Trent; Walker, Megan; Ganuza, Miguel; Holmfeldt, Per; Bordas, Marie; Kang, Guolian; Bi, Wenjian; Palmer, Lance E; Finkelstein, David; McKinney-Freeman, Shannon

2018-02-12

Hematopoietic stem and progenitor cells (HSPCs) are necessary for life-long blood production and replenishment of the hematopoietic system during stress. We recently reported that nuclear factor I/X (Nfix) promotes HSPC survival post-transplant. Here, we report that ectopic expression of Nfix in primary mouse HSPCs extends their ex vivo culture from about 20 to 40 days. HSPCs overexpressing Nfix display hypersensitivity to supportive cytokines and reduced apoptosis when subjected to cytokine deprivation relative to controls. Ectopic Nfix resulted in elevated levels of c-Mpl transcripts and cell surface protein on primary murine HSPCs as well as increased phosphorylation of STAT5, which is known to be activated down-stream of c-MPL. Blocking c-MPL signaling by removal of thrombopoietin or addition of a c-MPL neutralizing antibody negated the antiapoptotic effect of Nfix overexpression on cultured HSPCs. Furthermore, NFIX was capable of binding to and transcriptionally activating a proximal c-Mpl promoter fragment. In sum, these data suggest that NFIX-mediated upregulation of c-Mpl transcription can protect primitive hematopoietic cells from stress ex vivo. Stem Cells 2018. © AlphaMed Press 2018.

Syringin from stem bark of Fraxinus rhynchophylla protects Abeta(25-35)-induced toxicity in neuronal cells.

PubMed

Yang, Eun-Ju; Kim, Sang-In; Ku, Hyun-Yeong; Lee, Dong-Seok; Lee, Jong-Won; Kim, Yae-Sil; Seong, Yeon-Hee; Song, Kyung-Sik

2010-04-01

The medicinal herb Jinpi, derived from the dried stem barks of Fraxinus rhynchophylla belonging to Oleaceae is widely used as a variety of Korean folk remedies for anti-inflammatory, febricide, antidiarrhea, and antileukorrhea diseases. In the course of screening antidementia agents from natural products, F. rhynchophylla showed significant inhibitory activity toward Abeta(25-35)-induced neuronal cell death. An active principle was isolated and identified as syringin. When the neuroblastoma cells were exposed to 50 microM Abeta(25-35), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction rate (survival rate) decreased to 60.21 +/- 2.16% over control while syringin treated ones recovered cell viability up to 79.12 +/- 1.39% at 20 microM. In addition, 20 microM syringin almost completely removed Abeta(25-35)-induced reactive oxygen species. The neuroprotective effect of syringin seemed to be originated from the reduction of apoptosis since decrease in caspase-3 activity and expression, reduction in cleaved PARP, and DNA fragmentation were observed. These results suggest that F. rhynchophylla and syringin are expected to be useful for preventing Abeta(25-35)-induced neuronal cell damage.

Ginseng leaf-stem: bioactive constituents and pharmacological functions

PubMed Central

Wang, Hongwei; Peng, Dacheng; Xie, Jingtian

2009-01-01

Ginseng root is used more often than other parts such as leaf stem although extracts from ginseng leaf-stem also contain similar active ingredients with pharmacological functions. Ginseng's leaf-stems are more readily available at a lower cost than its root. This article reviews the pharmacological effects of ginseng leaf-stem on some diseases and adverse effects due to excessive consumption. Ginseng leaf-stem extract contains numerous active ingredients, such as ginsenosides, polysaccharides, triterpenoids, flavonoids, volatile oils, polyacetylenic alcohols, peptides, amino acids and fatty acids. The extract contains larger amounts of the same active ingredients than the root. These active ingredients produce multifaceted pharmacological effects on the central nervous system, as well as on the cardiovascular, reproductive and metabolic systems. Ginseng leaf-stem extract also has anti-fatigue, anti-hyperglycemic, anti-obesity, anti-cancer, anti-oxidant and anti-aging properties. In normal use, ginseng leaf-stem extract is quite safe; adverse effects occur only when it is over dosed or is of poor quality. Extracts from ginseng root and leaf-stem have similar multifaceted pharmacological activities (for example central nervous and cardiovascular systems). In terms of costs and source availability, however, ginseng leaf-stem has advantages over its root. Further research will facilitate a wider use of ginseng leaf-stem. PMID:19849852

Mouse decellularised liver scaffold improves human embryonic and induced pluripotent stem cells differentiation into hepatocyte-like cells

PubMed Central

Scottoni, Federico; Crowley, Claire; Fiadeiro, Rebeca; Maghsoudlou, Panagiotis; Pellegata, Alessandro Filippo; Mazzacuva, Francesca; Gjinovci, Asllan; Lyne, Anne-Marie; Zulini, Justine; Little, Daniel; Mosaku, Olukunbi; Kelly, Deirdre; De Coppi, Paolo; Gissen, Paul

2017-01-01

Liver transplantation is the definitive treatment of liver failure but donor organ shortage limits its availability. Stem cells are highly expandable and have the potential to differentiate into any specialist cell. Use of patient-derived induced Pluripotent Stem Cells (hiPSCs) has the additional advantage for organ regeneration therapies by removing the need for immunosuppression. We compared hepatocyte differentiation of human embryonic stem cells (hESCs) and hiPSCs in a mouse decellularised liver scaffold (3D) with standard in vitro protocol (2D). Mouse livers were decellularised preserving micro-architecture, blood vessel network and extracellular matrix. hESCs and hiPSCs were primed towards the definitive endoderm. Cells were then seeded either in 3D or 2D cultures and the hepatocyte differentiation was continued. Both hESCs and hiPSCs differentiated more efficiently in 3D than in 2D, with higher and earlier expression of mature hepatocyte marker albumin, lipid and glycogen synthesis associated with a decrease in expression of fetal hepatocyte marker alpha-fetoprotein. Thus we conclude that stem cell hepatocyte differentiation in 3D culture promotes faster cell maturation. This finding suggests that optimised 3D protocols could allow generation of mature liver cells not achieved so far in standard 2D conditions and lead to improvement in cell models of liver disease and regenerative medicine applications. PMID:29261712

Thyroid Hormone-Induced Activation of Notch Signaling is Required for Adult Intestinal Stem Cell Development During Xenopus Laevis Metamorphosis.

PubMed

Hasebe, Takashi; Fujimoto, Kenta; Kajita, Mitsuko; Fu, Liezhen; Shi, Yun-Bo; Ishizuya-Oka, Atsuko

2017-04-01

In Xenopus laevis intestine during metamorphosis, the larval epithelial cells are removed by apoptosis, and the adult epithelial stem (AE) cells appear concomitantly. They proliferate and differentiate to form the adult epithelium (Ep). Thyroid hormone (TH) is well established to trigger this remodeling by regulating the expression of various genes including Notch receptor. To study the role of Notch signaling, we have analyzed the expression of its components, including the ligands (DLL and Jag), receptor (Notch), and targets (Hairy), in the metamorphosing intestine by real-time reverse transcription-polymerase chain reaction and in situ hybridization or immunohistochemistry. We show that they are up-regulated during both natural and TH-induced metamorphosis in a tissue-specific manner. Particularly, Hairy1 is specifically expressed in the AE cells. Moreover, up-regulation of Hairy1 and Hairy2b by TH was prevented by treating tadpoles with a γ-secretase inhibitor (GSI), which inhibits Notch signaling. More importantly, TH-induced up-regulation of LGR5, an adult intestinal stem cell marker, was suppressed by GSI treatment. Our results suggest that Notch signaling plays a role in stem cell development by regulating the expression of Hairy genes during intestinal remodeling. Furthermore, we show with organ culture experiments that prolonged exposure of tadpole intestine to TH plus GSI leads to hyperplasia of secretory cells and reduction of absorptive cells. Our findings here thus provide evidence for evolutionarily conserved role of Notch signaling in intestinal cell fate determination but more importantly reveal, for the first time, an important role of Notch pathway in the formation of adult intestinal stem cells during vertebrate development. Stem Cells 2017;35:1028-1039. © 2016 The Authors STEM CELLS published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

A small modified hammerhead ribozyme and its conformational characteristics determined by mutagenesis and lattice calculation.

PubMed Central

Lustig, B; Lin, N H; Smith, S M; Jernigan, R L; Jeang, K T

1995-01-01

A prototypic hammerhead ribozyme has three helices that surround an asymmetrical central core loop. We have mutagenized a hammerhead type ribozyme. In agreement with previous studies, progressive removal of stem-loop II from a three stemmed ribozyme showed that this region is not absolutely critical for catalysis. However, complete elimination of stem II and its loop did reduce, but did not eliminate, function. In a stem-loop II-deleted ribozyme, activity was best preserved when a purine, preferably a G, was present at position 10.1. This G contributed to catalysis irregardless of its role as either one part of a canonical pair with a C residue at 11.1 or a lone nucleotide with C (11.1) deleted. Computational methods using lattices generated 87 million three-dimensional chain forms for a stem-loop II-deleted RNA complex that preserved one potential G.C base pair at positions 10.1 and 11.1. This exhaustive set of chain forms included one major class of structures with G(10.1) being spatially proximal to the GUCX cleavage site of the substrate strand. Strong correlations were observed between colinear arrangement of stems I and III, constraints of base-pairing in the central core loop, and one particular placement of G(10.1) relative to the cleavage site. Our calculations of a stem-loop II-deleted ribozyme indicate that without needing to invoke any other constraints, the inherent asymmetry in the lengths of the two loop strands (3 nt in one and 7 nt in the other) that compose the core and flank G10.1-C11.1 stipulated strongly this particular G placement. This suggests that the hammerhead ribozyme maintains an asymmetry in its internal loop for a necessary structure/function reason. Images PMID:7567466

Effect of Aureobasidium pullulans strains against Botrytis cinerea on kiwifruit during storage and on fruit nutritional composition.

PubMed

Di Francesco, A; Mari, M; Ugolini, L; Baraldi, E

2018-06-01

Kiwifruit, wounded at the equator or by pedicel removal, to simulate the stem end wound, were treated with Aureobasidium pullulans (L1 and L8 strains) and subsequently inoculated with conidia of Botrytis cinerea. Fruits were stored at -1 °C in normal refrigeration (NR) or in controlled atmosphere (CA) (2% O 2 ; 4.5% CO 2 ). After 4 months, both antagonists significantly reduced the disease in all experiments, L1 better than L8. In NR, their efficacy was higher than 80%. In CA, the disease reduction was lower: between 30% (L1) and 60% (L8). The ability of both strains to compete with the pathogen for nutrients was tested in kiwifruit juice (0.5%) by in vitro experiments. Antagonists significantly reduced pathogen conidia germination in water and in juice. An HPLC analysis was performed to define the amino acid composition of kiwifruit juice upon L1 and L8 treatment. L1 and L8 greatly increased the concentration of both glutamic and aspartic acids and stimulated the production of new amino acids, although at low concentrations. Each amino acid displayed an antifungal effect against mycelium growth of B. cinerea. Finally, L1 and L8, cold tolerant and active strains in CA, can be effectively applied to control the stem end rot of kiwifruit in long storage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Auditory steady-state responses in cochlear implant users: Effect of modulation frequency and stimulation artifacts.

PubMed

Gransier, Robin; Deprez, Hanne; Hofmann, Michael; Moonen, Marc; van Wieringen, Astrid; Wouters, Jan

2016-05-01

Previous studies have shown that objective measures based on stimulation with low-rate pulse trains fail to predict the threshold levels of cochlear implant (CI) users for high-rate pulse trains, as used in clinical devices. Electrically evoked auditory steady-state responses (EASSRs) can be elicited by modulated high-rate pulse trains, and can potentially be used to objectively determine threshold levels of CI users. The responsiveness of the auditory pathway of profoundly hearing-impaired CI users to modulation frequencies is, however, not known. In the present study we investigated the responsiveness of the auditory pathway of CI users to a monopolar 500 pulses per second (pps) pulse train modulated between 1 and 100 Hz. EASSRs to forty-three modulation frequencies, elicited at the subject's maximum comfort level, were recorded by means of electroencephalography. Stimulation artifacts were removed by a linear interpolation between a pre- and post-stimulus sample (i.e., blanking). The phase delay across modulation frequencies was used to differentiate between the neural response and a possible residual stimulation artifact after blanking. Stimulation artifacts were longer than the inter-pulse interval of the 500pps pulse train for recording electrodes ipsilateral to the CI. As a result the stimulation artifacts could not be removed by artifact removal on the bases of linear interpolation for recording electrodes ipsilateral to the CI. However, artifact-free responses could be obtained in all subjects from recording electrodes contralateral to the CI, when subject specific reference electrodes (Cz or Fpz) were used. EASSRs to modulation frequencies within the 30-50 Hz range resulted in significant responses in all subjects. Only a small number of significant responses could be obtained, during a measurement period of 5 min, that originate from the brain stem (i.e., modulation frequencies in the 80-100 Hz range). This reduced synchronized activity of brain stem responses in long-term severely-hearing impaired CI users could be an attribute of processes associated with long-term hearing impairment and/or electrical stimulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Utility-value intervention with parents increases students' STEM preparation and career pursuit.

PubMed

Rozek, Christopher S; Svoboda, Ryan C; Harackiewicz, Judith M; Hulleman, Chris S; Hyde, Janet S

2017-01-31

During high school, developing competence in science, technology, engineering, and mathematics (STEM) is critically important as preparation to pursue STEM careers, yet students in the United States lag behind other countries, ranking 35th in mathematics and 27th in science achievement internationally. Given the importance of STEM careers as drivers of modern economies, this deficiency in preparation for STEM careers threatens the United States' continued economic progress. In the present study, we evaluated the long-term effects of a theory-based intervention designed to help parents convey the importance of mathematics and science courses to their high-school-aged children. A prior report on this intervention showed that it promoted STEM course-taking in high school; in the current follow-up study, we found that the intervention improved mathematics and science standardized test scores on a college preparatory examination (ACT) for adolescents by 12 percentile points. Greater high-school STEM preparation (STEM course-taking and ACT scores) was associated with increased STEM career pursuit (i.e., STEM career interest, the number of college STEM courses, and students' attitudes toward STEM) 5 y after the intervention. These results suggest that the intervention can affect STEM career pursuit indirectly by increasing high-school STEM preparation. This finding underscores the importance of targeting high-school STEM preparation to increase STEM career pursuit. Overall, these findings demonstrate that a motivational intervention with parents can have important effects on STEM preparation in high school, as well as downstream effects on STEM career pursuit 5 y later.

Utility-value intervention with parents increases students’ STEM preparation and career pursuit

PubMed Central

Rozek, Christopher S.; Svoboda, Ryan C.; Harackiewicz, Judith M.; Hulleman, Chris S.; Hyde, Janet S.

2017-01-01

During high school, developing competence in science, technology, engineering, and mathematics (STEM) is critically important as preparation to pursue STEM careers, yet students in the United States lag behind other countries, ranking 35th in mathematics and 27th in science achievement internationally. Given the importance of STEM careers as drivers of modern economies, this deficiency in preparation for STEM careers threatens the United States’ continued economic progress. In the present study, we evaluated the long-term effects of a theory-based intervention designed to help parents convey the importance of mathematics and science courses to their high-school–aged children. A prior report on this intervention showed that it promoted STEM course-taking in high school; in the current follow-up study, we found that the intervention improved mathematics and science standardized test scores on a college preparatory examination (ACT) for adolescents by 12 percentile points. Greater high-school STEM preparation (STEM course-taking and ACT scores) was associated with increased STEM career pursuit (i.e., STEM career interest, the number of college STEM courses, and students’ attitudes toward STEM) 5 y after the intervention. These results suggest that the intervention can affect STEM career pursuit indirectly by increasing high-school STEM preparation. This finding underscores the importance of targeting high-school STEM preparation to increase STEM career pursuit. Overall, these findings demonstrate that a motivational intervention with parents can have important effects on STEM preparation in high school, as well as downstream effects on STEM career pursuit 5 y later. PMID:28096393

Genome Editing of the Blood: Opportunities and Challenges

PubMed Central

Porteus, Matthew H.

2015-01-01

The ability to remove blood cells, including hematopoietic stem cells (HSCs), from a person and then re-transplant them (hematopoietic stem cell transplantation (HSCT) is a well-established treatment paradigm that can be used in both the autologous setting or in the allogeneic setting. Using allogeneic HSCT can cure different genetic diseases of the blood but has significant limitations. An alternative to allogeneic HSCT is to transplant genetically modified HSCs instead. A powerful approach to the precision modification of HSCs is to use genome editing whereby the genome is modified with spatial precision (at an exact location) in the genome and sometimes with nucleotide precision (the exact nucleotide changes are introduced). The progress and challenges of genome editing of blood are discussed. PMID:26029496

CRISPR/Cas-Mediated Knockin in Human Pluripotent Stem Cells.

PubMed

Verma, Nipun; Zhu, Zengrong; Huangfu, Danwei

2017-01-01

Fluorescent reporter and epitope-tagged human pluripotent stem cells (hPSCs) greatly facilitate studies on the pluripotency and differentiation characteristics of these cells. Unfortunately traditional procedures to generate such lines are hampered by a low targeting efficiency that necessitates a lengthy process of selection followed by the removal of the selection cassette. Here we describe a procedure to generate fluorescent reporter and epitope tagged hPSCs in an efficient one-step process using the CRISPR/Cas technology. Although the method described uses our recently developed iCRISPR platform, the protocols can be adapted for general use with CRISPR/Cas or other engineered nucleases. The transfection procedures described could also be used for additional applications, such as overexpression or lineage tracing studies.

Antibody engineering of a cytotoxic monoclonal antibody 84 against human embryonic stem cells: Investigating the effects of multivalency on cytotoxicity.

PubMed

Klement, Maximilian; Zheng, Jiyun; Liu, Chengcheng; Tan, Heng-Liang; Wong, Victor Vai Tak; Choo, Andre Boon-Hwa; Lee, Dong-Yup; Ow, Dave Siak-Wei

2017-02-10

Antibody fragments have shown targeted specificity to their antigens, but only modest tissue retention times in vivo and in vitro. Multimerization has been used as a protein engineering tool to increase the number of binding units and thereby enhance the efficacy and retention time of antibody fragments. In this work, we explored the effects of valency using a series of self-assembling polypeptides based on the GCN4 leucine zipper multimerization domain fused to a single-chain variable fragment via an antibody upper hinge sequence. Four engineered antibody fragments with a valency from one to four antigen-binding units of a cytotoxic monoclonal antibody 84 against human embryonic stem cells (hESC) were constructed. We hypothesized that higher cytotoxicity would be observed for fragments with increased valency. Flow cytometry analysis revealed that the trimeric and tetrameric engineered antibody fragments resulted in the highest degree of cytotoxicity to the undifferentiated hESC, while the engineered antibody fragments were observed to have improved tissue penetration into cell clusters. Thus, a trade off was made for the trimeric versus tetrameric fragment due to improved tissue penetration. These results have direct implications for antibody-mediated removal of undifferentiated hESC during regenerative medicine and cell therapy. Copyright © 2016 The Author(s). Published by Elsevier B.V. All rights reserved.

Number of solutions effects in stem decision: support for the distinction between identification and production processes in priming.

PubMed

Barnhardt, Terrence M

2005-10-01

Three experiments explored the distinction between identification and production processes (e.g., Gabrieli et al., 1999). A stem decision test was introduced, in which participants were asked to state whether there were any English words that began with the presented three-letter stems. In Experiment 1, stem decision priming was robust for single-solution stems, but much reduced for many-solution stems. In Experiment 2, the solutions effect in stem decision was replicated in a within-subjects design, as was the contrast between the presence of priming in a many-solution stem completion test and the absence of priming in a many-solution stem decision test. In Experiment 3, for each critical many-solution stem in the stem decision test, participants studied three words that began with those three letters. Again, priming was not observed. These results were consistent with the notions that (a) many-solution stem completion relies on production processes, (b) the stem decision test eliminates production processes, and (c) single-solution priming relies on identification processes, regardless of whether the test is stem completion or stem decision.

Bone morphogenetic protein 9 (BMP9) induces effective bone formation from reversibly immortalized multipotent adipose-derived (iMAD) mesenchymal stem cells.

PubMed

Lu, Shun; Wang, Jing; Ye, Jixing; Zou, Yulong; Zhu, Yunxiao; Wei, Qiang; Wang, Xin; Tang, Shengli; Liu, Hao; Fan, Jiaming; Zhang, Fugui; Farina, Evan M; Mohammed, Maryam M; Song, Dongzhe; Liao, Junyi; Huang, Jiayi; Guo, Dan; Lu, Minpeng; Liu, Feng; Liu, Jianxiang; Li, Li; Ma, Chao; Hu, Xue; Lee, Michael J; Reid, Russell R; Ameer, Guillermo A; Zhou, Dongsheng; He, Tongchuan

2016-01-01

Regenerative medicine and bone tissue engineering using mesenchymal stem cells (MSCs) hold great promise as an effective approach to bone and skeletal reconstruction. While adipose tissue harbors MSC-like progenitors, or multipotent adipose-derived cells (MADs), it is important to identify and characterize potential biological factors that can effectively induce osteogenic differentiation of MADs. To overcome the time-consuming and technically challenging process of isolating and culturing primary MADs, here we establish and characterize the reversibly immortalized mouse multipotent adipose-derived cells (iMADs). The isolated mouse primary inguinal MAD cells are reversibly immortalized via the retrovirus-mediated expression of SV40 T antigen flanked with FRT sites. The iMADs are shown to express most common MSC markers. FLP-mediated removal of SV40 T antigen effectively reduces the proliferative activity and cell survival of iMADs, indicating the immortalization is reversible. Using the highly osteogenic BMP9, we find that the iMADs are highly responsive to BMP9 stimulation, express multiple lineage regulators, and undergo osteogenic differentiation in vitro upon BMP9 stimulation. Furthermore, we demonstrate that BMP9-stimulated iMADs form robust ectopic bone with a thermoresponsive biodegradable scaffold material. Collectively, our results demonstrate that the reversibly immortalized iMADs exhibit the characteristics of multipotent MSCs and are highly responsive to BMP9-induced osteogenic differentiation. Thus, the iMADs should provide a valuable resource for the study of MAD biology, which would ultimately enable us to develop novel and efficacious strategies for MAD-based bone tissue engineering.

Trophic transfer of soil arsenate and associated toxic effects in a plant-aphid-parasitoid system

NASA Astrophysics Data System (ADS)

Lee, Y. S.; Wee, J.; Lee, M.; Hong, J.; Cho, K.

2017-12-01

Terrestrial toxic effects of soil arsenic were studied using a model system consisting of soil which artificially treated with arsenic, Capsicum annum,Myzus persicae and Aphidus colemani. We investigated the transfer of arsenic in a soil-plant-aphid system and toxic effect of elevated arsenic through a plant-aphid-parasitoid system. To remove the effect of poor plant growth on aphid performance, test concentrations which have a no effect on health plant growth were selected. Arsenic concentration of growth medium, plant tissues (root, stem, leaf) aphids were measured to observe the arsenic transfer. Correlation matrix was made with arsenic in growth medium which extracted with three extractants (aquaregia, 0.01 M CaCl2 and deionized water), arsenic in plant tissues and plant performance. Toxic effects of elevated arsenic concentrations on each species were investigated at population level. Studied plant performances were dry weight of each tissue, elongation of roots and stems, area of leaves, chlorophyll content of leaves, protein content of leaves and sugar content of leaves. Mean development time, fecundity and honeydew excretion of the aphids and host choice capacity and parasitism success of the parasitoids were examined. In addition, enzyme activities of the plants and the aphids against reactive oxygen species (ROS) induced by arsenic stress were also investigated. The results suggest that arsenic concentration in plant tissues and aphids were elevated with increased concentration of arsenic in soil. Decreased fecundity and honeydew excretion of aphids were observed and decreased eclosion rate of parasitoids were observed with increased arsenic treatment in growth medium. The results showed low concentration of arsenic in soil can transfer through food chain and can impact on higher trophic level species.

Genome-Wide Association Studies with a Genomic Relationship Matrix: A Case Study with Wheat and Arabidopsis.

PubMed

Gianola, Daniel; Fariello, Maria I; Naya, Hugo; Schön, Chris-Carolin

2016-10-13

Standard genome-wide association studies (GWAS) scan for relationships between each of p molecular markers and a continuously distributed target trait. Typically, a marker-based matrix of genomic similarities among individuals ( G: ) is constructed, to account more properly for the covariance structure in the linear regression model used. We show that the generalized least-squares estimator of the regression of phenotype on one or on m markers is invariant with respect to whether or not the marker(s) tested is(are) used for building G,: provided variance components are unaffected by exclusion of such marker(s) from G: The result is arrived at by using a matrix expression such that one can find many inverses of genomic relationship, or of phenotypic covariance matrices, stemming from removing markers tested as fixed, but carrying out a single inversion. When eigenvectors of the genomic relationship matrix are used as regressors with fixed regression coefficients, e.g., to account for population stratification, their removal from G: does matter. Removal of eigenvectors from G: can have a noticeable effect on estimates of genomic and residual variances, so caution is needed. Concepts were illustrated using genomic data on 599 wheat inbred lines, with grain yield as target trait, and on close to 200 Arabidopsis thaliana accessions. Copyright © 2016 Gianola et al.

Where and When to Cut? Fluorescein Guidance for Brain Stem and Spinal Cord Tumor Surgery-Technical Note.

PubMed

Molina, Eric Suero; Stummer, Walter

2017-12-29

Spinal cord and brain stem lesions require a judicious approach with an optimized trajectory due to a clustering of functions on their surfaces. Intraoperative mapping helps locate function. To confidently locate such lesions, neuronavigation alone lacks the desired accuracy and is of limited use in the spinal cord. To evaluate the clinical value of fluoresceins for initial delineation of such critically located lesions. We evaluated fluorescein guidance in the surgical resection of lesions with blood-brain barrier disruption demonstrating contrast enhancement in magnet resonance imaging in the spinal cord and in the brain stem in 3 different patients. Two patients harbored a diffuse cervical and thoracic spinal cord lesion, respectively. Another patient suffered metastatic lesions in the brain stem and at the floor of the fourth ventricle. Low-dose fluorescein (4 mg/kg body weight) was applied after anesthesia induction and visualized using the Zeiss Pentero 900 Yellow560 filter (Carl Zeiss, Oberkochen, Germany). Fluorescein was helpful for locating lesions and for defining the best possible trajectory. During resection, however, we found unspecific propagation of fluorescein within the brain stem up to 6 mm within 3 h after application. As these lesions were otherwise distinguishable from surrounding tissue, monitoring resection was not an issue. Fluorescein guidance is a feasible tool for defining surgical entry zones when aiming for surgical removal of spinal cord and brain stem lesions. Unselective fluorescein extravasation cautions against using such methodology for monitoring completeness of resection. Providing the right timing, a window of pseudoselectivity could increase fluoresceins' clinical value in these cases. © Congress of Neurological Surgeons 2017.

Isolation and Propagation of Mesenchymal Stem Cells from the Lacrimal Gland

PubMed Central

You, Samantha; Kublin, Claire L.; Avidan, Orna; Miyasaki, David

2011-01-01

Purpose. Previously, it was reported that the murine lacrimal gland is capable of repair after experimentally induced injury and that the number of stem/progenitor cells was increased during the repair phase (2–3 days after injury). The aim of the present study was to determine whether these cells can be isolated from the lacrimal gland and propagated in vitro. Methods. Lacrimal gland injury was induced by injection of interleukin (IL)-1, and injection of saline vehicle served as control. Two and half days after injection, the lacrimal glands were removed and used to prepare explants or acinar cells for tissue culture. Cells derived from the explants and the acinar cells were grown in DMEM supplemented with 10% fetal bovine serum. Cells were stained for the stem cells markers, nestin, vimentin, ABCG2, and Sca-1. Cell proliferation was measured using an antibody against Ki67 or a cell-counting kit. The adipogenic capability of these cells was also tested in vitro. Results. Results show that nestin-positive cells can be isolated from IL-1–injected, but not saline-injected, lacrimal glands. A population of nestin-positive cells was also positive for vimentin, an intermediate filament protein expressed by mesenchymal cells. In addition, cultured cells expressed two other markers of stem cells, ABCG2 and Sca-1. These cells proliferated in vitro and can be induced to form adipocytes, attesting to their mesenchymal stem cell property. Conclusions. Murine lacrimal glands contain mesenchymal stem cells that seem to play a pivotal role in tissue repair. PMID:21178145

Pyrolysis of Plants After Phytoremediation of Contaminated Soil with Lead, Cadmium and Zinc.

PubMed

Özkan, Aysun; Günkaya, Zerrin; Banar, Müfide

2016-03-01

The aim of this study was to remediate lead (Pb), cadmium (Cd) and zinc (Zn) from contaminated soil and stabilize to pyrolysis solid product. To accomplish this, phytoremediation of soil contaminated with Pb, Cd and Zn by different plants (sunflower, corn and rape) was performed with and without ethylenediaminetetraacetic acid (EDTA). According to phytoremediation results, rape was the most effective plant with 72 %, 76 % and 77 % removal efficiency for Pb, Cd and Zn, respectively. Also, EDTA addition had no significant effect on translocation of the metals from roots to stems. According to pyrolysis results, Pb, Cd and Zn in the contaminated plants were stabilized in the ash/char fraction. In addition, the solid product can be safely landfilled as inert waste since its toxicity leaching value is lower than the limit values given in the Turkish Regulation on Landfilling of Wastes.

Effects of Telomerase and Telomere Length on Epidermal Stem Cell Behavior

NASA Astrophysics Data System (ADS)

Flores, Ignacio; Cayuela, María L.; Blasco, María A.

2005-08-01

A key process in organ homeostasis is the mobilization of stem cells out of their niches. We show through analysis of mouse models that telomere length, as well as the catalytic component of telomerase, Tert, are critical determinants in the mobilization of epidermal stem cells. Telomere shortening inhibited mobilization of stem cells out of their niche, impaired hair growth, and resulted in suppression of stem cell proliferative capacity in vitro. In contrast, Tert overexpression in the absence of changes in telomere length promoted stem cell mobilization, hair growth, and stem cell proliferation in vitro. The effects of telomeres and telomerase on stem cell biology anticipate their role in cancer and aging.

Doxycycline Enhances Survival and Self-Renewal of Human Pluripotent Stem Cells

PubMed Central

Chang, Mi-Yoon; Rhee, Yong-Hee; Yi, Sang-Hoon; Lee, Su-Jae; Kim, Rae-Kwon; Kim, Hyongbum; Park, Chang-Hwan; Lee, Sang-Hun

2014-01-01

Summary We here report that doxycycline, an antibacterial agent, exerts dramatic effects on human embryonic stem and induced pluripotent stem cells (hESC/iPSCs) survival and self-renewal. The survival-promoting effect was also manifest in cultures of neural stem cells (NSCs) derived from hESC/iPSCs. These doxycycline effects are not associated with its antibacterial action, but mediated by direct activation of a PI3K-AKT intracellular signal. These findings indicate doxycycline as a useful supplement for stem cell cultures, facilitating their growth and maintenance. PMID:25254347

Stem Cell Mobilizers: Novel Therapeutics for Acute Kidney Injury.

PubMed

Xu, Yue; Zeng, Song; Zhang, Qiang; Zhang, Zijian; Hu, Xiaopeng

2017-01-01

In the past decade, rapid developments in stem cell studies have occurred. Researchers have confirmed the plasticity of bone marrow stem cells and the repair and regeneration effects of bone marrow hematopoietic stem cells on solid organs. These findings have suggested the possibility of using bone marrow stem cell mobilizers to repair and regenerate injured organs. Recent studies on the effects of granulocyte colony-stimulating factor (G-CSF) and Plerixafor (AMD3100) on mouse acute kidney injury models have confirmed that the use of bone marrow stem cell mobilizers may be an effective therapeutic measure. This paper summarizes studies describing the effects of G-CSF and AMD3100 on various acute kidney injury models over the past 10 years. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Impacts of Professional Development in Integrated STEM Education on Teacher Self-Efficacy, Outcome Expectancy, and Stem Career Awareness

NASA Astrophysics Data System (ADS)

Knowles, J. Geoff

This research analyzed the effects of teacher professional development and lesson implementation in integrated Science, Technology, Engineering, and Math (STEM) on: 1.) Teacher self-efficacy and their confidence to teach specific STEM subjects; 2.) Teaching outcome expectancy beliefs concerning the impact of actions by teachers on student learning; and 3.) Teacher awareness of STEM careers. High school science and technology education teachers participating in the Teachers and Researchers Advancing Integrated Lessons in STEM (TRAILS) project experimental group attended a ten-day summer professional development institute designed to educate teachers in using an integrated STEM education model to implement integrated STEM lessons. The research design utilized a quasi-experimental nonequivalent comparison group design that incorporated an experimental group and an untreated comparison group with both pretest, posttest, and delayed posttest assessments on non-randomized participants. Teacher self-efficacy has been identified as a key factor in effective teaching and student learning, and teacher awareness of STEM careers impacts students as they consider career choices. The T-STEM Survey for teachers was given for the pretest and posttest assessments to measure attitudes and beliefs toward the specific constructs of this study. Significant effects of the TRAILS professional development were found in the teacher group (experimental or comparison) and teacher subject (technology or science) in pretest and posttest scores using cumulative link models for the constructs of teacher self-efficacy and beliefs to teach STEM subjects, teacher outcome expectancy beliefs, and teacher awareness of STEM careers. Effect sizes ranged from small to large varying by construct and assessment time. Highly significant p-values and effect sizes revealed impacts on science teachers were greater when teacher subject groups were analyzed separately.

Dasypodidae Borner, 1919 (Insecta, Hymenoptera): Proposed emendation of spelling to Dasypodaidae, so removing the homonymy with Dasypodidae Gray, 1821 (Mammalia, Xenarthra)

USGS Publications Warehouse

Alexander, B.A.; Michener, C.D.; Gardner, A.L.

1998-01-01

The family-group name DASYPODIDAE Borner, 1919 (Insecta, Hymenoptera) is a junior homonym Of DASYPODIDAE Gray, 1821 (Mammalia, Xenarthra). It is proposed that the homonymy between the two names, which relate to short-tongued bees and armadillos respectively, should be removed by emending the stem of the generic name Dasypoda Latreille, 1802, on which the insect familygroup name is based, to give DASYPODAIDAE, while leaving the mammalian name (based on Dasypus Linnaeus, 1758) unchanged. Dasypus novemcinctus Linnaeus, 1758, the type species of Dasypus, has a wide distribution in the southern United States, Central and South America. The genus Dasypoda ranges throughout most of the Palearctic region.

40 CFR 180.635 - Spinetoram; tolerances for residues.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.30 Brassica, head and stem, subgroup 5A 2.0 Brassica... Cherimoya 0.30 Citrus, dried pulp 0.50 Citrus, oil 3.0 Corn, sweet, kernel plus cob with husks removed 0.04... 0.30 Star fruit 0.30 Strawberry 1.0 Sugar apple 0.30 Ti, leaves 10 Vegetable, bulb, group 3, except...

40 CFR 180.635 - Spinetoram; tolerances for residues.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.30 Brassica, head and stem, subgroup 5A 2.0 Brassica... Cherimoya 0.30 Citrus, dried pulp 0.50 Citrus, oil 3.0 Corn, sweet, kernel plus cob with husks removed 0.04... 0.30 Star fruit 0.30 Strawberry 1.0 Sugar apple 0.30 Ti, leaves 10 Vegetable, bulb, group 3, except...

40 CFR 180.635 - Spinetoram; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Banana 0.25 Beet, sugar, molasses 0.75 Biriba 0.30 Brassica, head and stem, subgroup 5A 2.0 Brassica... Cherimoya 0.30 Citrus, dried pulp 0.50 Citrus, oil 3.0 Corn, sweet, kernel plus cob with husks removed 0.04... 0.30 Star fruit 0.30 Strawberry 1.0 Sugar apple 0.30 Ti, leaves 10 Vegetable, bulb, group 3, except...

Ground-layer plant community responses to even-age and uneven-age silvicultural treatments in Wisconsin northern hardwood forests

Treesearch

Cristel C. Kern; Brian J. Palik; Terry F. Strong

2006-01-01

We evaluated ground-layer plant diversity and community composition in northern hardwood forests among uncut controls and stands managed with even-age or uneven-age silvicultural systems. Even-age treatments included diameter-limit cuttings (20-cm diameter at 30-cm stem height) in 1952 and shelterwood removals in 1964. Uneven-age treatments included three intensities...

Sustainability of CD24 expression, cell proliferation and migration, cisplatin-resistance, and caspase-3 expression during mesenchymal-epithelial transition induced by the removal of TGF-β1 in A549 lung cancer cells.

PubMed

Kim, Seong-Kwan; Park, Jin-A; Zhang, Dan; Cho, Sang-Hyun; Yi, Hee; Cho, Soo-Min; Chang, Byung-Joon; Kim, Jin-Suk; Shim, Jae-Han; Abd El-Aty, A M; Shin, Ho-Chul

2017-08-01

Epithelial-mesenchymal transition (EMT) is a notable mechanism underlying cancer cell metastasis. Transforming growth factor β1 (TGF-β1) has been used to induce EMT; however, there is a lack of information regarding the role of TGF-β1 in mesenchymal-epithelial transition (MET). In the present study, EMT was induced in A549 lung cancer cells using TGF-β1 (TGF-β1-treated group) and MET was induced sequentially from the TGF-β1-treated group by removing the TGF-β1 (MET/return group). Untreated A549 lung cancer cells were used as a control. Characteristic features, including cancer stem cell markers [cluster of differentiation (CD)24, CD44 and CD133], cell proliferation and migration and diverse intracellular mechanisms, were observed in all groups. Using western blot analysis, the TGF-β1-treated group demonstrated increased vimentin and reduced E-cadherin expression, whereas the MET/return group demonstrated the opposite trend. Among cancer stem cell markers, the population of CD24 low cells was reduced in the TGF-β1-treated group. Furthermore, the G2/M phase cell cycle population, cisplatin-sensitivity, and cell proliferation and migration ability were increased in the TGF-β1-treated group. These features were unaltered in the MET/return group when compared to the TGF-β1-treated group. Immunoblotting revealed an increase in the levels of SMAD3, phosphorylated SMAD3, phosphorylated extracellular signal-regulated kinase and caspase-3, and a decrease in active caspase-3 levels in the TGF-β1-treated group. Increased caspase-3 and reduced active caspase-3 levels were observed in the MET/return group, similar to those in the TGF-β1-treated group; however, levels of other signalling proteins were unchanged compared with the control group. EMT induced by TGF-β1 was not preserved; however, stemness-associated properties (CD24 expression, caspase-3 expression, cell proliferation and cisplatin-resistance) were sustained following removal of TGF-β1.

Mesenchymal stem cells for acute lung injury: Preclinical evidence

PubMed Central

Matthay, Michael A.; Goolaerts, Arnaud; Howard, James P.; Lee, Jae Woo

2013-01-01

Several experimental studies have suggested that mesenchymal stem cells may have value for the treatment of clinical disorders, including myocardial infarction, diabetes, acute renal failure, sepsis, and acute lung injury. In preclinical studies, mesenchymal stem cells have been effective in reducing lung injury from endotoxin, live bacteria, bleomycin, and hyperoxia. In some studies, the cultured medium from mesenchymal stem cells has been as effective as the mesenchymal stem cells themselves. Several paracrine mediators that can mediate the effect of mesenchymal stem cells have been identified, including interleukin-10, interleukin-1ra, keratinocyte growth factor, and prostaglandin E2. Further preclinical studies are needed, as is planning for clinical trials for acute lung injury. PMID:21164399

LSD1 demethylase and the methyl-binding protein PHF20L1 prevent SET7 methyltransferase-dependent proteolysis of the stem-cell protein SOX2.

PubMed

Zhang, Chunxiao; Hoang, Nam; Leng, Feng; Saxena, Lovely; Lee, Logan; Alejo, Salvador; Qi, Dandan; Khal, Anthony; Sun, Hong; Lu, Fei; Zhang, Hui

2018-03-09

The pluripotency-controlling stem-cell protein SRY-box 2 (SOX2) plays a pivotal role in maintaining the self-renewal and pluripotency of embryonic stem cells and also of teratocarcinoma or embryonic carcinoma cells. SOX2 is monomethylated at lysine 119 (Lys-119) in mouse embryonic stem cells by the SET7 methyltransferase, and this methylation triggers ubiquitin-dependent SOX2 proteolysis. However, the molecular regulators and mechanisms controlling SET7-induced SOX2 proteolysis are unknown. Here, we report that in human ovarian teratocarcinoma PA-1 cells, methylation-dependent SOX2 proteolysis is dynamically regulated by the LSD1 lysine demethylase and a methyl-binding protein, PHD finger protein 20-like 1 (PHF20L1). We found that LSD1 not only removes the methyl group from monomethylated Lys-117 (equivalent to Lys-119 in mouse SOX2), but it also demethylates monomethylated Lys-42 in SOX2, a reaction that SET7 also regulated and that also triggered SOX2 proteolysis. Our studies further revealed that PHF20L1 binds both monomethylated Lys-42 and Lys-117 in SOX2 and thereby prevents SOX2 proteolysis. Down-regulation of either LSD1 or PHF20L1 promoted SOX2 proteolysis, which was prevented by SET7 inactivation in both PA-1 and mouse embryonic stem cells. Our studies also disclosed that LSD1 and PHF20L1 normally regulate the growth of pluripotent mouse embryonic stem cells and PA-1 cells by preventing methylation-dependent SOX2 proteolysis. In conclusion, our findings reveal an important mechanism by which the stability of the pluripotency-controlling stem-cell protein SOX2 is dynamically regulated by the activities of SET7, LSD1, and PHF20L1 in pluripotent stem cells. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Laser biomodulation on stem cells

NASA Astrophysics Data System (ADS)

Liu, Timon C.; Duan, Rui; Li, Yan; Li, Xue-Feng; Tan, Li-Ling; Liu, Songhao

2001-08-01

Stem cells are views from the perspectives of their function, evolution, development, and cause. Counterintuitively, most stem cells may arise late in development, to act principally in tissue renewal, thus ensuring an organisms long-term survival. Surprisingly, recent reports suggest that tissue-specific adult stem cells have the potential to contribute to replenishment of multiple adult tissues. Stem cells are currently in the news for two reasons: the successful cultivation of human embryonic stem cell lines and reports that adult stem cells can differentiate into developmentally unrelated cell types, such as nerve cells into blood cells. The spotlight on stem cells has revealed gaps in our knowledge that must be filled if we are to take advantage of their full potential for treating devastating degenerative diseases such as Parkinsons's disease and muscular dystrophy. We need to know more about the intrinsic controls that keep stem cells as stem cells or direct them along particular differentiation pathways. Such intrinsic regulators are, in turn, sensitive to the influences of the microenvironment, or niche, where stem cells normally reside. Both intrinsic and extrinsic signals regular stem cell fate and some of these signals have now been identified. Vacek et al and Wang et al have studied the effect of low intensity laser on the haemopoietic stem cells in vitro. There experiments show there is indeed the effect of low intensity laser on the haemopoietic stem cells in vitro, and the present effect is the promotion of haemopoietic stem cells proliferation. In other words, low intensity laser irradiation can act as an extrinsic signal regulating stem cell fate. In this paper, we study how low intensity laser can be used to regulate stem cell fate from the viewpoint of collective phototransduction.

Effect of nitrogen fertilization and fungicides on Botryosphaeria stem blight lesion development on detached blueberry stems

USDA-ARS?s Scientific Manuscript database

Botryosphaeria stem blight is a destructive disease of blueberries. Field observations indicate stem blight is more severe on vigorous plants than on slower growing plants. Two studies compared the effect of two types of fertilizers applied at four rates and nine fungicides on lesion development fo...

Evaluation of a Mouse Embryonic Stem Cell Adherent Cell Differentiation and Cytotoxicity (ACDC) assay (SOT)

EPA Science Inventory

The Embryonic Stem Cell Test (EST) has been used to evaluate the effects of xenobiotics using three endpoints, stem cell differentiation, stem cell viability and 3T3-cell viability. Our research goal is to establish amodel system that would evaluate chemical effects using a singl...

Differences in uptake and translocation of hexavalent and trivalent chromium by two species of willows.

PubMed

Yu, Xiao-Zhang; Gu, Ji-Dong; Xing, Li-Qun

2008-11-01

Uptake and translocation of chromium (Cr) by two willow species was investigated. Intact pre-rooted weeping willows (Salix babylonica L.) and hankow willows (Salix matsudana Koidz) were grown hydroponically and spiked with hexavalent chromium [Cr (VI)] or trivalent chromium [Cr (III)] at 25.0 +/- 0.5 degrees C for 120 h. Removal of leaves was also performed as a treatment to quantify the effect of transpiration on uptake and translocation of either of the Cr species. Although the two willow species were able to eliminate Cr (VI) and Cr (III) from the hydroponic solution, significant differences in the removal rate for both chemical species were observed between the two willows (p < 0.05): faster removal rate for Cr (III) than Cr (VI) was detected in both willow species; hankow willows showed higher removal potential for both chemical species than weeping willows. Remarkable decreases in the removal rates for both Cr species were detected in the willows with leaves removed (p < 0.05). The results from the treatments spiked with Cr (VI) also revealed that Cr was more mobile in plant materials of hankow willows than that in weeping willows (p < 0.01), while higher translocation efficiency of Cr was observed in weeping willows than hankow willows for the Cr (III) treated (p < 0.01). However, a convincing decrease in the translocation efficiency due to the removal of leaves was only observed in the treatments spiked with Cr (VI) (p < 0.05). Substantial differences existed in the distribution of Cr species in plant materials after exposure of either of the chemical forms: roots and lower stems were the major sites for accumulation in weeping willows exposed to Cr (VI) and Cr (III), respectively; in contrast roots were the only sink in hankow willows exposed to both chemical species. The capacity of willows to assimilate both Cr species was also evaluated using detached leaves and roots of both willow species in sealed glass vessels in vivo. The results indicated that detached roots showed a more remarkable capacity to remove Cr (III) from the hydroponic solution than Cr (VI) (p < 0.01). Although detached leaves of both willow species were able to efficiently eliminate Cr (III), neither of them reduced the concentration of Cr (VI) in the solution. The results suggests that different mechanisms for uptake, assimilation and translocation of Cr (VI) and Cr (III) exist in different willow species and phytoremediation of Cr should consider this factor for the proposed target effectively.

Cryo-imaging of fluorescently labeled single cells in a mouse

NASA Astrophysics Data System (ADS)

Steyer, Grant J.; Roy, Debashish; Salvado, Olivier; Stone, Meredith E.; Wilson, David L.

2009-02-01

We developed a cryo-imaging system to provide single-cell detection of fluorescently labeled cells in mouse, with particular applicability to stem cells and metastatic cancer. The Case cryoimaging system consists of a fluorescence microscope, robotic imaging positioner, customized cryostat, PC-based control system, and visualization/analysis software. The system alternates between sectioning (10-40 μm) and imaging, collecting color brightfield and fluorescent blockface image volumes >60GB. In mouse experiments, we imaged quantum-dot labeled stem cells, GFP-labeled cancer and stem cells, and cell-size fluorescent microspheres. To remove subsurface fluorescence, we used a simplified model of light-tissue interaction whereby the next image was scaled, blurred, and subtracted from the current image. We estimated scaling and blurring parameters by minimizing entropy of subtracted images. Tissue specific attenuation parameters were found [uT : heart (267 +/- 47.6 μm), liver (218 +/- 27.1 μm), brain (161 +/- 27.4 μm)] to be within the range of estimates in the literature. "Next image" processing removed subsurface fluorescence equally well across multiple tissues (brain, kidney, liver, adipose tissue, etc.), and analysis of 200 microsphere images in the brain gave 97+/-2% reduction of subsurface fluorescence. Fluorescent signals were determined to arise from single cells based upon geometric and integrated intensity measurements. Next image processing greatly improved axial resolution, enabled high quality 3D volume renderings, and improved enumeration of single cells with connected component analysis by up to 24%. Analysis of image volumes identified metastatic cancer sites, found homing of stem cells to injury sites, and showed microsphere distribution correlated with blood flow patterns. We developed and evaluated cryo-imaging to provide single-cell detection of fluorescently labeled cells in mouse. Our cryo-imaging system provides extreme (>60GB), micron-scale, fluorescence, and bright field image data. Here we describe our image preprocessing, analysis, and visualization techniques. Processing improves axial resolution, reduces subsurface fluorescence by 97%, and enables single cell detection and counting. High quality 3D volume renderings enable us to evaluate cell distribution patterns. Applications include the myriad of biomedical experiments using fluorescent reporter gene and exogenous fluorophore labeling of cells in applications such as stem cell regenerative medicine, cancer, tissue engineering, etc.

Flower power: Floral and resource manipulations reveal how and why reproductive trade-offs occur for lowbush blueberry (Vaccinium angustifolium).

PubMed

Bajcz, Alex W; Drummond, Francis A

2017-08-01

Plant reproductive trade-offs are thought to be caused by resource limitations or other constraints, but more empirical support for these hypotheses would be welcome. Additionally, quantitative characterization of these trade-offs, as well as consideration of whether they are linear, could yield additional insights. We expanded our flower removal research on lowbush blueberry ( Vaccinium angustifolium ) to explore the nature of and causes of its reproductive trade-offs. We used fertilization, defoliation, positionally biased flower removal, and multiple flower removal levels to discern why reproductive trade-offs occur in this taxon and to plot these trade-offs along two continuous axes. We found evidence through defoliation that vegetative mass per stem may trade off with reproductive effort in lowbush blueberry because the two traits compete for limited carbon. Also, several traits including ripe fruit production per reproductive node and fruit titratable acidity may be "sink-limited"-they decline with increasing reproductive effort because average reproductive structure quality declines. We found no evidence that reproductive trade-offs were caused by nitrogen limitation. Use of reproductive nodes remaining per stem as a measure of reproductive effort indicated steeper trade-offs than use of the proportion of nodes remaining. For five of six traits, we found evidence that the trade-off could be concave down or up instead of strictly linear. Synthesis . To date, studies have aimed primarily at identifying plant reproductive trade-offs. However, understanding how and why these trade-offs occur represent the exciting and necessary next steps for this line of inquiry.

Ni(II) biosorption by Cassia fistula (Golden Shower) biomass.

PubMed

Hanif, Muhammad Asif; Nadeem, Raziya; Bhatti, Haq Nawaz; Ahmad, Najum Rashid; Ansari, Tariq Mehmood

2007-01-10

Cassia fistula is a fast-growing, medium-sized, deciduous tree which is now widely cultivated worldwide as an ornamental tree for its beautiful showy yellow flowers. Methods are required to reuse fallen leaves, branches, stem bark and pods when they start getting all over lawn. This investigation studies the use of these non-useful parts of C. fistula as naturally occurring biosorbent for the batch removal of Ni(II) in a well stirred system under different experimental conditions. The data showed that the maximum pH (pHmax) for efficient sorption of Ni(II) was 6 at which evaluated biosorbent dosage, biosorbent particle size, initial concentrations of Ni(II) and sorption time were 0.1 g/100 mL, <0.255 mm, up to 200 mg/L and 720 min, respectively. The experimental results were analyzed in terms of Langmuir and Freundlich isotherms. The Langmuir isotherm model fitted well to data of Ni(II) biosorption by C. fistula biomass as compared to the model of Freundlich. The kinetic studies showed that the sorption rates could be described better by a second order expression than by a more commonly applied Lagergren equation. The magnitude of the Gibbs free energy values indicates spontaneous nature of the sorption process. The sorption ability of C. fistula biomass for Ni(II) removal tends to be in the order: leaves

The Efficacy of a Student Organization for STEM Students

ERIC Educational Resources Information Center

Mwaikinda, Sekela R.; Aruguete, Mara S.

2016-01-01

Our study tests the effectiveness of STEM Alliance, a student organization aimed at increasing academic and social support for students pursuing STEM majors. STEM Alliance offered weekly, extracurricular activities aimed at preparing students for graduate school and STEM careers. Students attending STEM Alliance events showed greater academic and…

Shear stress influences the pluripotency of murine embryonic stem cells in stirred suspension bioreactors.

PubMed

Gareau, Tia; Lara, Giovanna G; Shepherd, Robert D; Krawetz, Roman; Rancourt, Derrick E; Rinker, Kristina D; Kallos, Michael S

2014-04-01

Pluripotent embryonic stem cells (ESCs) have been used increasingly in research as primary material for various tissue-engineering applications. Pluripotency, or the ability to give rise to all cells of the body, is an important characteristic of ESCs. Traditional methods use leukaemia inhibitory factor (LIF) to maintain murine embryonic stem cell (mESC) pluripotency in static and bioreactor cultures. When LIF is removed from mESCs in static cultures, pluripotency genes are downregulated and the cultures will spontaneously differentiate. Recently we have shown the maintenance of pluripotency gene expression of mESCs in stirred suspension bioreactors during differentiation experiments in the absence of LIF. This is undesired in a differentiation experiment, where the goal is downregulation of pluripotency gene expression and upregulation of gene expression characteristic to the differentiation. Thus, the objective of this study was to examine how effectively different levels of shear stress [100 rpm (6 dyne/cm(2) ), 60 rpm (3 dyne/cm(2) )] maintained and influenced pluripotency in suspension bioreactors. The pluripotency markers Oct-4, Nanog, Sox-2 and Rex-1 were assessed using gene expression profiles and flow-cytometry analysis and showed that shear stress does maintain and influence the gene expression of certain pluripotency markers. Some significant differences between the two levels of shear stress were seen and the combination of shear stress and LIF was observed to synergistically increase the expression of certain pluripotency markers. Overall, this study provides a better understanding of the environmental conditions within suspension bioreactors and how these conditions affect the pluripotency of mESCs. Copyright © 2012 John Wiley & Sons, Ltd.

Long-acting peptidomimergic control of gigantism caused by pituitary acidophilic stem cell adenoma.

PubMed

Maheshwari, H G; Prezant, T R; Herman-Bonert, V; Shahinian, H; Kovacs, K; Melmed, S

2000-09-01

Gigantism is caused by GH hypersecretion occurring before epiphyseal long bone closure and usually is associated with pituitary adenoma. A 15-yr-old female patient presented with accelerated growth due to a large pituitary tumor that was surgically resected to relieve pressure effects. Second surgery to remove residual tumor tissue was followed by administration of octreotide LAR, a long-acting depot somatostatin analog, together with long-acting cabergoline. Height was over the 95th percentile, with evidence of a recent growth spurt. Serum GH levels were more than 60 ng/mL (normal, <10 ng/mL) with no suppression to 75 g oral glucose, and serum PRL (>8,000 ng/mL; normal, <23 ng/mL) and insulin-like growth factor I levels (845 ng/mL; age-matched normal, 242-660 ng/mL) were elevated. Histology, immunostaining, and electron microscopy demonstrated a pituitary acidophil stem cell adenoma. Tumor tissue expressed both somatostatin receptor type 2 and dopamine receptor type 2. The Gs alpha subunit, GHRH receptor, and MEN1 genes were intact, and tumor tissue abundantly expressed pituitary tumor transforming gene (PTTG). Serum GH and PRL levels were controlled after two surgeries, and with continued cabergoline and octreotide LAR GH, PRL, and insulin-like growth factor I levels were normalized. In conclusion, administration of long-acting somatostatin analog every 4 weeks in combination with a long-acting dopamine agonist biweekly controlled biochemical parameters and accelerated growth in a patient with gigantism caused by a rare pituitary acidophil stem cell adenoma.

Impact of Solid and Hollow Varieties of Winter and Spring Wheat on Severity of Wheat Stem Sawfly (Hymenoptera: Cephidae) Infestations and Yield and Quality of Grain.

PubMed

Szczepaniec, Adrianna; Glover, Karl D; Berzonsky, William

2015-10-01

Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), has recently emerged as a key pest of wheat (Triticum aestivum L.) in the Great Plains and Canadian provinces. The expanding impact of WSS has caused considerable economic losses to wheat production. Solid-stem varieties of wheat remain the only effective measure of suppression of WSS, and the goal of this research was to test whether five solid- and hollow-stem varieties of winter and spring wheat reduce survival of WSS in South Dakota. We reported that solid-stem varieties had significantly lower numbers of WSS larvae, and this effect was especially evident when WSS infestation rates exceeded 15%. We also observed that the yield of solid-stem varieties was significantly lower than hollow-stem varieties when the abundance of WSS was low, but not when populations of WSS were relatively high. We did not observe consistent differences in grain quality between solid- and hollow-stem varieties, however, and in case of protein levels of grain, solid-stem wheat varieties performed better than hollow-stem wheat. We conclude that solid-stem varieties of wheat appear to effectively suppress WSS survival, and reduced yield of these varieties is less apparent when populations of C. cinctus are high enough to affect the yield of hollow-stem wheat. This is the first report to describe the effectiveness of solid-stem varieties of wheat on WSS in South Dakota. More research in the state is necessary before more robust conclusions can be drawn. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effect of Cutting Velocity / Stem Size on the Efficiency of NRCRI Cassave Stem Cutting Machine

NASA Astrophysics Data System (ADS)

Ikejiofor, M. C.

2012-11-01

The developed NRCRI (National Root Crops Research Institute) cassava stem cutting machine was evaluated. The cassava stems from the variety TME 419 were used. The sizes of the stem used were 1.8, 2.0, 2.3 and 2.6cm. Also, different cutting velocities of 1.20, 1.23 and 1.32m/s were used. The stakes produced has length of 2.5cm. Analysis of variance in RCBD was used to evaluate the effect of the cutting velocity and the stem size on the efficiency of the cutting machine. The result of the analysis showed that the cutting velocity had very highly significant effect, while the stem size had no significant effect at 5% level on the efficiency of the cutting machine. The data obtained also showed that the highest and least cutting efficiencies of 99.42 and 94.71% were obtained with the machine cutting velocities of 1.2 and 1.32m/s respectively.

Eckol suppresses maintenance of stemness and malignancies in glioma stem-like cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyun, Kyung-Hwan; Yoon, Chang-Hwan; Kim, Rae-Kwon

A subpopulation of cancer cells with stem cell properties is responsible for tumor maintenance and progression, and may contribute to resistance to anticancer treatments. Thus, compounds that target cancer stem-like cells could be usefully applied to destroy cancer. In this study, we investigated the effect of Eckol, a phlorotannin compound, on stemness and malignancies in glioma stem-like cells. To determine whether Eckol targets glioma stem-like cells, we examined whether Eckol treatment could change the expression levels of glioma stem-like cell markers and self-renewal-related proteins as well as the sphere forming ability, and the sensitivity to anticancer treatments. Alterations in themore » malignant properties of sphere-derived cells by Eckol were also investigated by soft-agar colony forming assay, by xenograft assay in nude mice, and by cell invasion assay. Treatment of sphere-forming glioma cells with Eckol effectively decreased the sphere formation as well as the CD133{sup +} cell population. Eckol treatment suppressed expression of the glioma stem-like cell markers and the self-renewal-related proteins without cell death. Moreover, treatment of glioma stem-like cells with Eckol significantly attenuated anchorage-independent growth on soft agar and tumor formation in xenograft mice. Importantly, Eckol treatment effectively reduced the resistance of glioma stem-like cells to ionizing radiation and temozolomide. Treatment of glioma stem-like cells with Eckol markedly blocked both phosphoinositide 3-kinase-Akt and Ras-Raf-1-Erk signaling pathways. These results indicate that the natural phlorotannin Eckol suppresses stemness and malignancies in glioma stem-like cells, and thereby makes glioma stem-like cells more sensitive to anticancer treatments, providing novel therapeutic strategies targeting specifically cancer stem-like cells.« less

The regulatory sciences for stem cell-based medicinal products.

PubMed

Yuan, Bao-Zhu; Wang, Junzhi

2014-06-01

Over the past few years, several new achievements have been made from stem cell studies, many of which have moved up from preclinical stages to early, or from early to middle or late, stages thanks to relatively safe profile and preliminary evidence of effectiveness. Moreover, some stem cell-based products have been approved for marketing by different national regulatory authorities. However, many critical issues associated mainly with incomplete understanding of stem cell biology and the relevant risk factors, and lack of effective regulations still exist and need to be urgently addressed, especially in countries where establishment of appropriate regulatory system just commenced. More relevantly, the stem cell regulatory sciences need to be established or improved to more effectively evaluate quality, safety and efficacy of stem cell products, and for building up the appropriate regulatory framework. In this review, we summarize some new achievements in stem cell studies, especially the preclinical and clinical studies, the existing regulations, and the associated challenges, and we then propose some considerations for improving stem cell regulatory sciences with a goal of promoting the steadfast growth of the well-regulated stem cell therapies abreast of evolvement of stem cell sciences and technologies.

The Effect of Laser Irradiation on Adipose Derived Stem Cell Proliferation and Differentiation

NASA Astrophysics Data System (ADS)

Abrahamse, H.; de Villiers, J.; Mvula, B.

2009-06-01

There are two fundamental types of stem cells: Embryonic Stem cells and Adult Stem cells. Adult Stem cells have a more restricted potential and can usually differentiate into a few different cell types. In the body these cells facilitate the replacement or repair of damaged or diseased cells in organs. Low intensity laser irradiation was shown to increase stem cell migration and stimulate proliferation and it is thought that treatment of these cells with laser irradiation may increase the stem cell harvest and have a positive effect on the viability and proliferation. Our research is aimed at determining the effect of laser irradiation on differentiation of Adipose Derived Stem Cells (ADSCs) into different cell types using a diode laser with a wavelength of 636 nm and at 5 J/cm2. Confirmation of stem cell characteristics and well as subsequent differentiation were assessed using Western blot analysis and cellular morphology supported by fluorescent live cell imaging. Functionality of subsequent differentiated cells was confirmed by measuring adenosine triphosphate (ATP) production and cell viability.

The Effectiveness of Stemming for Natural-Language Access to Slovene Textual Data.

ERIC Educational Resources Information Center

Popovic, Mirko; Willett, Peter

1992-01-01

Reports on the use of stemming for Slovene language documents and queries in free-text retrieval systems and demonstrates that an appropriate stemming algorithm results in an increase in retrieval effectiveness when compared with nonstemming processing. A comparison is made with stemming of English versions of the same documents and queries. (24…

Therapeutic Potential, Challenges and Future Perspective of Cancer Stem Cells in Translational Oncology: A Critical Review.

PubMed

Shukla, Gaurav; Khera, Harvinder Kour; Srivastava, Amit Kumar; Khare, Piush; Patidar, Rahul; Saxena, Rajiv

2017-01-01

Stem cell research is a rapidly developing field that offers effective treatment for a variety of malignant and non-malignant diseases. Stem cell is a regenerative medicine associated with the replacement, repair, and restoration of injured tissue. Stem cell research is a promising field having maximum therapeutic potential. Cancer stem cells (CSCs) are the cells within the tumor that posses capacity of selfrenewal and have a root cause for the failure of traditional therapies leading to re-occurrence of cancer. CSCs have been identified in blood, breast, brain, and colon cancer. Traditional therapies target only fast growing tumor mass, but not slow-dividing cancer stem cells. It has been shown that embryonic pathways such as Wnt, Hedgehog and Notch, control self-renewal capacity and involved in cancer stem cell maintenance. Targeting of these pathways may be effective in eradicating cancer stem cells and preventing chemotherapy and radiotherapy resistance. Targeting CSCs has become one of the most effective approaches to improve the cancer survival by eradicating the main root cause of cancer. The present review will address, in brief, the importance of cancer stem cells in targeting cancer as better and effective treatment along with a concluding outlook on the scope and challenges in the implication of cancer stem cells in translational oncology. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Autophagy in Human Embryonic Stem Cells

PubMed Central

Tra, Thien; Gong, Lan; Kao, Lin-Pin; Li, Xue-Lei; Grandela, Catarina; Devenish, Rodney J.; Wolvetang, Ernst; Prescott, Mark

2011-01-01

Autophagy (macroautophagy) is a degradative process that involves the sequestration of cytosolic material including organelles into double membrane vesicles termed autophagosomes for delivery to the lysosome. Autophagy is essential for preimplantation development of mouse embryos and cavitation of embryoid bodies. The precise roles of autophagy during early human embryonic development, remain however largely uncharacterized. Since human embryonic stem cells constitute a unique model system to study early human embryogenesis we investigated the occurrence of autophagy in human embryonic stem cells. We have, using lentiviral transduction, established multiple human embryonic stem cell lines that stably express GFP-LC3, a fluorescent marker for the autophagosome. Each cell line displays both a normal karyotype and pluripotency as indicated by the presence of cell types representative of the three germlayers in derived teratomas. GFP expression and labelling of autophagosomes is retained after differentiation. Baseline levels of autophagy detected in cultured undifferentiated hESC were increased or decreased in the presence of rapamycin and wortmannin, respectively. Interestingly, autophagy was upregulated in hESCs induced to undergo differentiation by treatment with type I TGF-beta receptor inhibitor SB431542 or removal of MEF secreted maintenance factors. In conclusion we have established hESCs capable of reporting macroautophagy and identify a novel link between autophagy and early differentiation events in hESC. PMID:22110659

Investigations Concerning Cavitation and Frost Fatigue in Clonal 84K Poplar Using High-Resolution Cavitron Measurements1[OPEN

PubMed Central

Feng, Feng; Ding, Fei; Tyree, Melvin T.

2015-01-01

Both drought and freezing-thawing of stems induce a loss of hydraulic conductivity (percentage loss of conductivity [PLC]) in woody plants. Drought-induced PLC is often accompanied by physical damage to pit membranes, causing a shift in vulnerability curves (cavitation fatigue). Hence, if cavitated stems are flushed to remove embolisms, the next vulnerability curve is different (shifted to lower tensions). The 84K poplar (Populus alba × Populus glandulosa) clone has small vessels that should be immune from frost-induced PLC, but results demonstrated that freezing-thawing in combination with tension synergistically increased PLC. Frost fatigue has already been defined, which is similar to cavitation fatigue but induced by freezing. Frost fatigue caused a transition from a single to a dual Weibull curve, but drought-fatigued stems had single Weibull curves shifted to lower tensions. Studying the combined impact of tension plus freezing on fatigue provided evidence that the mechanism of frost fatigue may be the extra water tension induced by freezing or thawing while spinning stems in a centrifuge rather than direct ice damage. A hypothesis is advanced that tension is enhanced as ice crystals grow or melt during the freeze or thaw event, respectively, causing a nearly identical fatigue event to that induced by drought. PMID:25786827

Radial Head Prosthesis Removal: a Retrospective Case Series of 14 Patients

PubMed Central

Neuhaus, Valentin; Christoforou, Dimitrios C.; Kachooei, Amir Reza; Jupiter, Jesse B.; Ring, David C.; Mudgal, Chaitanya S.

2015-01-01

Background: The purpose of this study was to report the preoperative complaints and postoperative outcome of patients after removal of the radial head prosthesis. Methods: This is a retrospective review of 14 adult patients (6 females and 8 males) from 2007 to 2011, who underwent radial head prosthesis removal by three surgeons. The average time between implantation and removal was 23 months (range from 2 weeks to 12 years, median 12 months). Results: The leading reported complaints before removal were restricted mobility of the elbow (active range of motion of less than 100 degrees) in 6, pain in 3, and pain together with restricted mobility in 4 patients. The objective findings before removal were restricted mobility of the elbow in 10 (71%), capitellar cartilage wear, loose implants, and heterotopic ossification each in 8 (57%), subluxation of the radio-capitellar joint or malpositioning of the stem in 5 (36%), and chronic infection in 2 (14%) patients. All patients with pain had wear of the capitellar cartilage on radiographs. The ulnar nerve was decompressed in four patients at the time of removal. Four patients underwent a subsequent operation for postoperative ulnar nerve symptoms 5 to 21 months after removal. Four patients were still complaining about persistent pain at the last follow-up visit. Except two patients, the total range of motion improved with a mean of 34 degrees (range 5 to 70) after a mean follow-up of 11 months. Conclusions: Removal of radial head prosthesis improved function and lessened pain in our case series. The reoperation rate was yet nearly 30% due to ulnar neuritis. Selective ulnar nerve decompression at the time of removal must be evaluated, especially in patients with expected large gain in range of motion after removal. PMID:26110173

Digitization and Visualization of Greenhouse Tomato Plants in Indoor Environments

PubMed Central

Li, Dawei; Xu, Lihong; Tan, Chengxiang; Goodman, Erik D.; Fu, Daichang; Xin, Longjiao

2015-01-01

This paper is concerned with the digitization and visualization of potted greenhouse tomato plants in indoor environments. For the digitization, an inexpensive and efficient commercial stereo sensor—a Microsoft Kinect—is used to separate visual information about tomato plants from background. Based on the Kinect, a 4-step approach that can automatically detect and segment stems of tomato plants is proposed, including acquisition and preprocessing of image data, detection of stem segments, removing false detections and automatic segmentation of stem segments. Correctly segmented texture samples including stems and leaves are then stored in a texture database for further usage. Two types of tomato plants—the cherry tomato variety and the ordinary variety are studied in this paper. The stem detection accuracy (under a simulated greenhouse environment) for the cherry tomato variety is 98.4% at a true positive rate of 78.0%, whereas the detection accuracy for the ordinary variety is 94.5% at a true positive of 72.5%. In visualization, we combine L-system theory and digitized tomato organ texture data to build realistic 3D virtual tomato plant models that are capable of exhibiting various structures and poses in real time. In particular, we also simulate the growth process on virtual tomato plants by exerting controls on two L-systems via parameters concerning the age and the form of lateral branches. This research may provide useful visual cues for improving intelligent greenhouse control systems and meanwhile may facilitate research on artificial organisms. PMID:25675284

Digitization and visualization of greenhouse tomato plants in indoor environments.

PubMed

Li, Dawei; Xu, Lihong; Tan, Chengxiang; Goodman, Erik D; Fu, Daichang; Xin, Longjiao

2015-02-10

This paper is concerned with the digitization and visualization of potted greenhouse tomato plants in indoor environments. For the digitization, an inexpensive and efficient commercial stereo sensor-a Microsoft Kinect-is used to separate visual information about tomato plants from background. Based on the Kinect, a 4-step approach that can automatically detect and segment stems of tomato plants is proposed, including acquisition and preprocessing of image data, detection of stem segments, removing false detections and automatic segmentation of stem segments. Correctly segmented texture samples including stems and leaves are then stored in a texture database for further usage. Two types of tomato plants-the cherry tomato variety and the ordinary variety are studied in this paper. The stem detection accuracy (under a simulated greenhouse environment) for the cherry tomato variety is 98.4% at a true positive rate of 78.0%, whereas the detection accuracy for the ordinary variety is 94.5% at a true positive of 72.5%. In visualization, we combine L-system theory and digitized tomato organ texture data to build realistic 3D virtual tomato plant models that are capable of exhibiting various structures and poses in real time. In particular, we also simulate the growth process on virtual tomato plants by exerting controls on two L-systems via parameters concerning the age and the form of lateral branches. This research may provide useful visual cues for improving intelligent greenhouse control systems and meanwhile may facilitate research on artificial organisms.

Metabostemness: a new cancer hallmark.

PubMed

Menendez, Javier A; Alarcón, Tomás

2014-01-01

The acquisition of and departure from stemness in cancer tissues might not only be hardwired by genetic controllers, but also by the pivotal regulatory role of the cellular metabotype, which may act as a "starter dough" for cancer stemness traits. We have coined the term metabostemness to refer to the metabolic parameters causally controlling or functionally substituting the epitranscriptional orchestration of the genetic reprograming that redirects normal and tumor cells toward less-differentiated cancer stem cell (CSC) cellular states. Certain metabotypic alterations might operate as pivotal molecular events rendering a cell of origin susceptible to epigenetic rewiring required for the acquisition of aberrant stemness and, concurrently, of refractoriness to differentiation. The metabostemness attribute can remove, diminish, or modify the nature of molecular barriers present in Waddington's epigenetic landscapes, thus allowing differentiated cells to more easily (re)-enter into CSC cellular macrostates. Activation of the metabostemness trait can poise cells with chromatin states competent for rapid dedifferentiation while concomitantly setting the idoneous metabolic stage for later reprograming stimuli to finish the journey from non-cancerous into tumor-initiating cells. Because only a few permitted metabotypes will be compatible with the operational properties owned by CSC cellular states, the metabostemness property provides a new framework through which to pharmacologically resolve the apparently impossible problem of discovering drugs aimed to target the molecular biology of the cancer stemness itself. The metabostemness cancer hallmark generates a shifting oncology theory that should guide a new era of metabolo-epigenetic cancer precision medicine.

Metabostemness: A New Cancer Hallmark

PubMed Central

Menendez, Javier A.; Alarcón, Tomás

2014-01-01

The acquisition of and departure from stemness in cancer tissues might not only be hardwired by genetic controllers, but also by the pivotal regulatory role of the cellular metabotype, which may act as a “starter dough” for cancer stemness traits. We have coined the term metabostemness to refer to the metabolic parameters causally controlling or functionally substituting the epitranscriptional orchestration of the genetic reprograming that redirects normal and tumor cells toward less-differentiated cancer stem cell (CSC) cellular states. Certain metabotypic alterations might operate as pivotal molecular events rendering a cell of origin susceptible to epigenetic rewiring required for the acquisition of aberrant stemness and, concurrently, of refractoriness to differentiation. The metabostemness attribute can remove, diminish, or modify the nature of molecular barriers present in Waddington’s epigenetic landscapes, thus allowing differentiated cells to more easily (re)-enter into CSC cellular macrostates. Activation of the metabostemness trait can poise cells with chromatin states competent for rapid dedifferentiation while concomitantly setting the idoneous metabolic stage for later reprograming stimuli to finish the journey from non-cancerous into tumor-initiating cells. Because only a few permitted metabotypes will be compatible with the operational properties owned by CSC cellular states, the metabostemness property provides a new framework through which to pharmacologically resolve the apparently impossible problem of discovering drugs aimed to target the molecular biology of the cancer stemness itself. The metabostemness cancer hallmark generates a shifting oncology theory that should guide a new era of metabolo-epigenetic cancer precision medicine. PMID:25325014

Cement-in-cement stem revision for Vancouver type B periprosthetic femoral fractures after total hip arthroplasty. A 3-year follow-up of 23 cases.

PubMed

Briant-Evans, Toby W; Veeramootoo, Darmaraja; Tsiridis, Eleftherios; Hubble, Matthew J

2009-10-01

Revision surgery for periprosthetic femoral fractures around an unstable cemented femoral stem traditionally requires removal of existing cement. We propose a new technique whereby a well-fixed cement mantle can be retained in cases with simple fractures that can be reduced anatomically when a cemented revision is planned. This technique is well established in femoral stem revision, but not in association with a fracture. We treated 23 Vancouver type B periprosthetic femoral fractures by reducing the fracture and cementing a revision stem into the pre-existing cement mantle, with or without supplementary fixation. 3 patients died in the first 6 months for reasons unrelated to surgery. In addition, 1 was too frail to attend follow-up and was therefore excluded from the study, and 1 patient underwent revision surgery for a nonunion. The remaining 18 cases all healed with radiographic union after an average time of 4.4 (2-11) months. There was no sign of loosening or subsidence of the revision stems within the old cement mantle in any of these cases at the most recent follow-up after an average of 3 (0.3-9) years. Our results support the use of the cement-in-cement revision in anatomically reducible periprosthetic fractures with a well-preserved pre-existing cement mantle. This technique is particularly useful for the elderly patient and for those who are not fit for prolonged surgical procedures.

Changes in human bone marrow fat content associated with changes in hematopoietic stem cell numbers and cytokine levels with aging

PubMed Central

Tuljapurkar, Sonal R; McGuire, Timothy R; Brusnahan, Susan K; Jackson, John D; Garvin, Kevin L; Kessinger, Margaret A; Lane, Judy T; O' Kane, Barbara J; Sharp, John G

2011-01-01

Hematological deficiencies increase with aging, including anemias, reduced responses to hematopoietic stress and myelodysplasias. This investigation tested the hypothesis that increased bone marrow (BM) fat content in humans with age was associated with decreased numbers of side population (SP) hematopoietic stem cells, and this decrease correlated with changes in cytokine levels. BM was obtained from the femoral head and trochanteric region of the femur removed at surgery for total hip replacement (N = 100 subjects). In addition, BM from cadavers (N = 36), with no evidence of hip disease, was evaluated for fat content. Whole trabecular marrow samples were ground in a sterile mortar and pestle, and cellularity and lipid content determined. Marrow cells were stained with Hoechst dye and SP profiles were acquired. Plasma levels of insulin-like growth factor (IGF)-1, stromal-derived factor (SDF)-1 and interleukin (IL)-6 were measured using ELISA. Fat content in the BM of human subjects and cadavers increased with age. The numbers of SP stem cells in BM as well as plasma IGF-1 and SDF-1 levels decreased in correlation with increased BM fat. IL-6 had no relationship to changes in marrow fat. These data suggest that increased BM fat may be associated with a decreased number of SP stem cells and IGF-1 and SDF-1 levels with aging. These data further raise a more general question as to the role of adipose cells in the regulation of tissue stem cells. PMID:21923862

FireStem2D – A Two-Dimensional Heat Transfer Model for Simulating Tree Stem Injury in Fires

PubMed Central

Chatziefstratiou, Efthalia K.; Bohrer, Gil; Bova, Anthony S.; Subramanian, Ravishankar; Frasson, Renato P. M.; Scherzer, Amy; Butler, Bret W.; Dickinson, Matthew B.

2013-01-01

FireStem2D, a software tool for predicting tree stem heating and injury in forest fires, is a physically-based, two-dimensional model of stem thermodynamics that results from heating at the bark surface. It builds on an earlier one-dimensional model (FireStem) and provides improved capabilities for predicting fire-induced mortality and injury before a fire occurs by resolving stem moisture loss, temperatures through the stem, degree of bark charring, and necrotic depth around the stem. We present the results of numerical parameterization and model evaluation experiments for FireStem2D that simulate laboratory stem-heating experiments of 52 tree sections from 25 trees. We also conducted a set of virtual sensitivity analysis experiments to test the effects of unevenness of heating around the stem and with aboveground height using data from two studies: a low-intensity surface fire and a more intense crown fire. The model allows for improved understanding and prediction of the effects of wildland fire on injury and mortality of trees of different species and sizes. PMID:23894599

Effect of Bradyrhizobium photosynthesis on stem nodulation of Aeschynomene sensitiva

PubMed Central

Giraud, Eric; Hannibal, Laure; Fardoux, Joel; Verméglio, Andre; Dreyfus, Bernard

2000-01-01

Some leguminous species of the genus Aeschynomene are specifically stem-nodulated by photosynthetic bradyrhizobia. To study the effect of bacterial photosynthesis during symbiosis, we generated a photosynthesis-negative mutant of the Bradyrhizobium sp. strain ORS278 symbiont of Aeschynomene sensitiva. The presence of a functional photosynthetic unit in bacteroids and the high expression of the photosynthetic genes observed in stem nodules demonstrate that the bacteria are photosynthetically active during stem symbiosis. Stem inoculation by the photosynthetic mutant gave a 50% decrease in stem-nodule number, which reduced nitrogen fixation activity and plant growth in the same proportion. These results indicate an important role of bacterial photosynthesis in the efficiency of stem nodulation. PMID:11114184

Unexpected embolization of Teflon pledget in the left main stem during: a Bentall operation.

PubMed

Rubino, Antonino S; Serraino, Giuseppe F; Marsico, Roberto; Renzulli, Attilio

2011-01-01

We report the case of an 83-year-old man in whom acute left ventricular failure with ventricular arrhythmic storm developed during a Bentall operation. During re-exploration of the annular and coronary ostial anastomoses, no abnormality was seen, and none of the common sequelae of aortic root replacement was evident. The application of retrograde cardioplegia yielded a Teflon pledget that had migrated into the distal part of the left main stem. The pledget was removed, the anastomoses were reestablished, and the patient recovered uneventfully. This case suggests that left ostial anastomosis re-exploration should be carefully considered when no other cause of coronary insufficiency is obvious, and that retrograde cardioplegia may be useful to detect embolization in the left coronary system.

Unexpected Embolization of Teflon Pledget in the Left Main Stem during a Bentall Operation

PubMed Central

Rubino, Antonino S.; Serraino, Giuseppe F.; Marsico, Roberto; Renzulli, Attilio

2011-01-01

We report the case of an 83-year-old man in whom acute left ventricular failure with ventricular arrhythmic storm developed during a Bentall operation. During re-exploration of the annular and coronary ostial anastomoses, no abnormality was seen, and none of the common sequelae of aortic root replacement was evident. The application of retrograde cardioplegia yielded a Teflon pledget that had migrated into the distal part of the left main stem. The pledget was removed, the anastomoses were reestablished, and the patient recovered uneventfully. This case suggests that left ostial anastomosis re-exploration should be carefully considered when no other cause of coronary insufficiency is obvious, and that retrograde cardioplegia may be useful to detect embolization in the left coronary system. PMID:22163143

Fifteen-year patterns of soil carbon and nitrogen following biomass harvesting

USGS Publications Warehouse

Kurth, Valerie J.; D'Amato, Anthony W.; Palik, Brian J.; Bradford, John B.

2014-01-01

The substitution of forest-derived woody biofuels for fossil fuel energy has garnered increasing attention in recent years, but information regarding the mid- and long-term effects on soil productivity is limited. We investigated 15-yr temporal trends in forest floor and mineral soil (0–30 cm) C and N pools in response to organic matter removal treatments (OMR; stem-only harvest, SOH; whole-tree harvest, WTH; and whole-tree plus forest floor removal, FFR) at three edaphically distinct aspen (Populus tremuloides Michx. and P. grandidentata Michx.) forests in the Great Lakes region. The OMR and temporal effects were generally site specific, and both were most evident in the forest floor and combined profile (mineral soil and forest floor) compared with the mineral soil alone. Forest floor and combined profile C and N pools were generally similar in the SOH and WTH treatments, suggesting that slash retention has little impact on soil C and N in this time frame. Temporal changes in C and N at one of the three sites were consistent with patterns documented following exotic earthworm invasion, but mineral soil pools at the other two sites were stable over time. Power analyses demonstrated that significant effects were more likely to be detected for temporal differences than the effects of OMR and in the combined profile than in the mineral soil. Our findings are consistent with previous work demonstrating that OMR effects on soil C and N pools are site specific and more apparent in the forest floor than the mineral soil.

Relative importance of modularity and other morphological attributes on different types of lithic point weapons: assessing functional variations.

PubMed

González-José, Rolando; Charlin, Judith

2012-01-01

The specific using of different prehistoric weapons is mainly determined by its physical properties, which provide a relative advantage or disadvantage to perform a given, particular function. Since these physical properties are integrated to accomplish that function, examining design variables and their pattern of integration or modularity is of interest to estimate the past function of a point. Here we analyze a composite sample of lithic points from southern Patagonia likely formed by arrows, thrown spears and hand-held points to test if they can be viewed as a two-module system formed by the blade and the stem, and to evaluate the degree in which shape, size, asymmetry, blade: stem length ratio, and tip angle explain the observed variance and differentiation among points supposedly aimed to accomplish different functions. To do so we performed a geometric morphometric analysis on 118 lithic points, departing from 24 two-dimensional landmark and semi landmarks placed on the point's contour. Klingenberg's covariational modularity tests were used to evaluate different modularity hypotheses, and a composite PCA including shape, size, asymmetry, blade: stem length ratio, and tip angle was used to estimate the importance of each attribute to explaining variation patterns. Results show that the blade and the stem can be seen as "near decomposable units" in the points integrating the studied sample. However, this modular pattern changes after removing the effects of reduction. Indeed, a resharpened point tends to show a tip/rest of the point modular pattern. The composite PCA analyses evidenced three different patterns of morphometric attributes compatible with arrows, thrown spears, and hand-held tools. Interestingly, when analyzed independently, these groups show differences in their modular organization. Our results indicate that stone tools can be approached as flexible designs, characterized by a composite set of interacting morphometric attributes, and evolving on a modular way.

CRISPR/Cas9-mediated reversibly immortalized mouse bone marrow stromal stem cells (BMSCs) retain multipotent features of mesenchymal stem cells (MSCs).

PubMed

Hu, Xue; Li, Li; Yu, Xinyi; Zhang, Ruyi; Yan, Shujuan; Zeng, Zongyue; Shu, Yi; Zhao, Chen; Wu, Xingye; Lei, Jiayan; Li, Yasha; Zhang, Wenwen; Yang, Chao; Wu, Ke; Wu, Ying; An, Liping; Huang, Shifeng; Ji, Xiaojuan; Gong, Cheng; Yuan, Chengfu; Zhang, Linghuan; Liu, Wei; Huang, Bo; Feng, Yixiao; Zhang, Bo; Haydon, Rex C; Luu, Hue H; Reid, Russell R; Lee, Michael J; Wolf, Jennifer Moriatis; Yu, Zebo; He, Tong-Chuan

2017-12-19

Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells that can undergo self-renewal and differentiate into multi-lineages. Bone marrow stromal stem cells (BMSCs) represent one of the most commonly-used MSCs. In order to overcome the technical challenge of maintaining primary BMSCs in long-term culture, here we seek to establish reversibly immortalized mouse BMSCs (imBMSCs). By exploiting CRISPR/Cas9-based homology-directed-repair (HDR) mechanism, we target SV40T to mouse Rosa26 locus and efficiently immortalize mouse BMSCs (i.e., imBMSCs). We also immortalize BMSCs with retroviral vector SSR #41 and establish imBMSC41 as a control line. Both imBMSCs and imBMSC41 exhibit long-term proliferative capability although imBMSC41 cells have a higher proliferation rate. SV40T mRNA expression is 130% higher in imBMSC41 than that in imBMSCs. However, FLP expression leads to 86% reduction of SV40T expression in imBMSCs, compared with 63% in imBMSC41 cells. Quantitative genomic PCR analysis indicates that the average copy number of SV40T and hygromycin is 1.05 for imBMSCs and 2.07 for imBMSC41, respectively. Moreover, FLP expression removes 92% of SV40T in imBMSCs at the genome DNA level, compared with 58% of that in imBMSC41 cells, indicating CRISPR/Cas9 HDR-mediated immortalization of BMSCs can be more effectively reversed than that of retrovirus-mediated random integrations. Nonetheless, both imBMSCs and imBMSC41 lines express MSC markers and are highly responsive to BMP9-induced osteogenic, chondrogenic and adipogenic differentiation in vitro and in vivo . Thus, the engineered imBMSCs can be used as a promising alternative source of primary MSCs for basic and translational research in the fields of MSC biology and regenerative medicine.

Relative Importance of Modularity and Other Morphological Attributes on Different Types of Lithic Point Weapons: Assessing Functional Variations

PubMed Central

González-José, Rolando; Charlin, Judith

2012-01-01

The specific using of different prehistoric weapons is mainly determined by its physical properties, which provide a relative advantage or disadvantage to perform a given, particular function. Since these physical properties are integrated to accomplish that function, examining design variables and their pattern of integration or modularity is of interest to estimate the past function of a point. Here we analyze a composite sample of lithic points from southern Patagonia likely formed by arrows, thrown spears and hand-held points to test if they can be viewed as a two-module system formed by the blade and the stem, and to evaluate the degree in which shape, size, asymmetry, blade: stem length ratio, and tip angle explain the observed variance and differentiation among points supposedly aimed to accomplish different functions. To do so we performed a geometric morphometric analysis on 118 lithic points, departing from 24 two-dimensional landmark and semi landmarks placed on the point's contour. Klingenberg's covariational modularity tests were used to evaluate different modularity hypotheses, and a composite PCA including shape, size, asymmetry, blade: stem length ratio, and tip angle was used to estimate the importance of each attribute to explaining variation patterns. Results show that the blade and the stem can be seen as “near decomposable units” in the points integrating the studied sample. However, this modular pattern changes after removing the effects of reduction. Indeed, a resharpened point tends to show a tip/rest of the point modular pattern. The composite PCA analyses evidenced three different patterns of morphometric attributes compatible with arrows, thrown spears, and hand-held tools. Interestingly, when analyzed independently, these groups show differences in their modular organization. Our results indicate that stone tools can be approached as flexible designs, characterized by a composite set of interacting morphometric attributes, and evolving on a modular way. PMID:23094104

Novel method to load multiple genes onto a mammalian artificial chromosome.

PubMed

Tóth, Anna; Fodor, Katalin; Praznovszky, Tünde; Tubak, Vilmos; Udvardy, Andor; Hadlaczky, Gyula; Katona, Robert L

2014-01-01

Mammalian artificial chromosomes are natural chromosome-based vectors that may carry a vast amount of genetic material in terms of both size and number. They are reasonably stable and segregate well in both mitosis and meiosis. A platform artificial chromosome expression system (ACEs) was earlier described with multiple loading sites for a modified lambda-integrase enzyme. It has been shown that this ACEs is suitable for high-level industrial protein production and the treatment of a mouse model for a devastating human disorder, Krabbe's disease. ACEs-treated mutant mice carrying a therapeutic gene lived more than four times longer than untreated counterparts. This novel gene therapy method is called combined mammalian artificial chromosome-stem cell therapy. At present, this method suffers from the limitation that a new selection marker gene should be present for each therapeutic gene loaded onto the ACEs. Complex diseases require the cooperative action of several genes for treatment, but only a limited number of selection marker genes are available and there is also a risk of serious side-effects caused by the unwanted expression of these marker genes in mammalian cells, organs and organisms. We describe here a novel method to load multiple genes onto the ACEs by using only two selectable marker genes. These markers may be removed from the ACEs before therapeutic application. This novel technology could revolutionize gene therapeutic applications targeting the treatment of complex disorders and cancers. It could also speed up cell therapy by allowing researchers to engineer a chromosome with a predetermined set of genetic factors to differentiate adult stem cells, embryonic stem cells and induced pluripotent stem (iPS) cells into cell types of therapeutic value. It is also a suitable tool for the investigation of complex biochemical pathways in basic science by producing an ACEs with several genes from a signal transduction pathway of interest.

CRISPR/Cas9-mediated reversibly immortalized mouse bone marrow stromal stem cells (BMSCs) retain multipotent features of mesenchymal stem cells (MSCs)

PubMed Central

Hu, Xue; Li, Li; Yu, Xinyi; Zhang, Ruyi; Yan, Shujuan; Zeng, Zongyue; Shu, Yi; Zhao, Chen; Wu, Xingye; Lei, Jiayan; Li, Yasha; Zhang, Wenwen; Yang, Chao; Wu, Ke; Wu, Ying; An, Liping; Huang, Shifeng; Ji, Xiaojuan; Gong, Cheng; Yuan, Chengfu; Zhang, Linghuan; Liu, Wei; Huang, Bo; Feng, Yixiao; Zhang, Bo; Haydon, Rex C.; Luu, Hue H.; Reid, Russell R.; Lee, Michael J.; Wolf, Jennifer Moriatis; Yu, Zebo; He, Tong-Chuan

2017-01-01

Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells that can undergo self-renewal and differentiate into multi-lineages. Bone marrow stromal stem cells (BMSCs) represent one of the most commonly-used MSCs. In order to overcome the technical challenge of maintaining primary BMSCs in long-term culture, here we seek to establish reversibly immortalized mouse BMSCs (imBMSCs). By exploiting CRISPR/Cas9-based homology-directed-repair (HDR) mechanism, we target SV40T to mouse Rosa26 locus and efficiently immortalize mouse BMSCs (i.e., imBMSCs). We also immortalize BMSCs with retroviral vector SSR #41 and establish imBMSC41 as a control line. Both imBMSCs and imBMSC41 exhibit long-term proliferative capability although imBMSC41 cells have a higher proliferation rate. SV40T mRNA expression is 130% higher in imBMSC41 than that in imBMSCs. However, FLP expression leads to 86% reduction of SV40T expression in imBMSCs, compared with 63% in imBMSC41 cells. Quantitative genomic PCR analysis indicates that the average copy number of SV40T and hygromycin is 1.05 for imBMSCs and 2.07 for imBMSC41, respectively. Moreover, FLP expression removes 92% of SV40T in imBMSCs at the genome DNA level, compared with 58% of that in imBMSC41 cells, indicating CRISPR/Cas9 HDR-mediated immortalization of BMSCs can be more effectively reversed than that of retrovirus-mediated random integrations. Nonetheless, both imBMSCs and imBMSC41 lines express MSC markers and are highly responsive to BMP9-induced osteogenic, chondrogenic and adipogenic differentiation in vitro and in vivo. Thus, the engineered imBMSCs can be used as a promising alternative source of primary MSCs for basic and translational research in the fields of MSC biology and regenerative medicine. PMID:29340096

Tomato type and post-treatment water rinse affect efficacy of acid washes against Salmonella enterica inoculated on stem scars of tomatoes and product quality.

PubMed

Fan, Xuetong; Gurtler, Joshua B; Sokorai, Kimberly J B

2018-09-02

A study was conducted to evaluate the effects of post-treatment rinsing with water on the inactivation efficacy of acid treatments against Salmonella inoculated onto stem scar areas of two types of tomatoes. In addition, impact on fruit quality was investigated during 21 days post-treatment storage at 10 °C. A four-strain cocktail of Salmonella enterica (S. Montevideo, S. Newport, S. Saintpaul, and S. Typhimurium) was inoculated onto stem scar areas of grape and large round tomatoes. The inoculated fruits were then treated for 2 min with the following solutions: water, 2% lactic acid +2% acetic acid +2% levulinic acid, 1.7% lactic acid +1.7% acetic acid +1.7% levulinic acid, and 3% lactic acid +3% acetic acid. After treatments, half of the fruits were rinsed with water while another half were not rinsed. Non-inoculated grape tomatoes for quality analysis were treated with the same solutions with and without subsequent water rinse. Results demonstrated that the acid combinations reduced populations of Salmonella enterica on the stem scar area of grape tomatoes by 1.52-1.90 log CFU/fruit, compared with the non-treated control while water wash and rinse removed the bacterium by only 0.23-0.30 log CFU/fruit. On the stem scar of large round tomatoes, the same acid treatments achieved 3.54 log CFU/fruit reduction of the pathogen. The varying response to the acid washes between grape and large round tomatoes seems to be related to the differences in surface characteristics of stem scar areas observed with SEM. Rinsing with water after acid combination treatments did not significantly affect the efficacy of the treatments in either grape or large round tomatoes. Acidic off-odor was detected on fruits treated with acid combination without water rinse 1 day after treatment while water rinse eliminated the off-odor. The acid treatments with and without water rinse did not consistently affect appearance, color, firmness, or lycopene or ascorbic acid contents of tomatoes during 21-days storage at 10 °C. Considering the similarity in antimicrobial efficacy between the fruits with and without water rinse following acid treatments, and the elimination of acidic odor by water rinse, fruits should be rinsed with water after acid treatments. Overall, our results demonstrated that the acids were more effective in inactivating Salmonella on large round tomatoes than on grape tomatoes, and water rinses following acid treatments eliminated the acidic odor without affecting the efficacy of the acids against Salmonella. Published by Elsevier B.V.

Cadmium analysis using field deployable nano-band electrode system and its removal using electrocoagulation

NASA Astrophysics Data System (ADS)

Guttula, Mallikarjuna Murthy

Cadmium (Cd) is an extremely toxic metal commonly found in industrial workplaces. Major industrial releases of Cd stem from waste streams, leaching of landfills, and from a variety of operations that involve cadmium or zinc. Particularly, cadmium can be released to drinking water from the corrosion of some galvanized plumbing and water main pipe materials. The United State Environmental Protection Agency (USEPA) has set the Maximum Contaminant Level (MCL) for cadmium at 5 ppb. Long term exposure of cadmium above the MCL results in kidney, liver, bone and blood damage. An accurate and rapid measurement of cadmium in the field remains a technical challenge. In this work, a relatively new method of a Nano-Band Electrode system using anodic stripping voltammetry was optimized by changing deposition potential, electrolyte, and plating time. We efficiently used Electrocoagulation remove cadmium from wastewater and obtained a removal efficiency of +/-99%. Removal mechanism of cadmium in electrocoagulation was also proposed with the help of X-ray Diffraction (XRD), Attenuated Total Reflection - Fourier Transform Infra Red Spectroscopy (ATR-FTIR), and Scanning Electron Microscopy and Energy Dispersive Spectrometer (SEM-EDS).

Increasing College Students' Interest and Engagement in STEM: A Comparison of Strategies for Challenging STEM Stereotypes

NASA Astrophysics Data System (ADS)

Shin, Jiyun Elizabeth L.

Increasing science, technology, engineering, and mathematics (STEM) graduates has become an important part of the education agenda in the U.S. in recent years. Stereotypes about STEM (i.e., belief that STEM abilities are innate, and that European American men are best suited for STEM) have been identified as one of the critical factors that may contribute to low recruitment and retention of STEM students. Drawing from the literatures on biological essentialism and role models, this study compared different strategies for challenging STEM stereotypes among undergraduate students in STEM and non-STEM fields. STEM stereotypes were challenged directly with research articles that provided non-biological explanations for STEM success and interest (a strategy used in the essentialism research) and indirectly with biographies of successful STEM role models who are underrepresented in their field and who succeeded through hard work (a strategy used in the role model research). Contrary to the predictions, exposure to the role model biographies, research articles, or combination of both did not have statistically significant effects on participants' reported STEM interest and academic intentions. Possible explanations for the lack of significant findings as well as suggestions for developing effective interventions to promote STEM engagement among students are discussed.

Stem Cell Therapy: A Promising Therapeutic Method for Intracerebral Hemorrhage.

PubMed

Gao, Liansheng; Xu, Weilin; Li, Tao; Chen, Jingyin; Shao, Anwen; Yan, Feng; Chen, Gao

2018-01-01

Spontaneous intracerebral hemorrhage (ICH) is one type of the most devastating cerebrovascular diseases worldwide, which causes high morbidity and mortality. However, efficient treatment is still lacking. Stem cell therapy has shown good neuroprotective and neurorestorative effect in ICH and is a promising treatment. In this study, our aim was to review the therapeutic effects, strategies, related mechanisms and safety issues of various types of stem cell for ICH treatment. Numerous studies had demonstrated the therapeutic effects of diverse stem cell types in ICH. The potential mechanisms include tissue repair and replacement, neurotrophy, promotion of neurogenesis and angiogenesis, anti-apoptosis, immunoregulation and anti-inflammation and so forth. The microenvironment of the central nervous system (CNS) can also influence the effects of stem cell therapy. The detailed therapeutic strategies for ICH treatment such as cell type, the number of cells, time window, and the routes of medication delivery, varied greatly among different studies and had not been determined. Moreover, the safety issues of stem cell therapy for ICH should not be ignored. Stem cell therapy showed good therapeutic effect in ICH, making it a promising treatment. However, safety should be carefully evaluated, and more clinical trials are required before stem cell therapy can be extensively applied to clinical use.

Logging damage to dominant and codominant residual stems in thinned West Virginia cherry-maple stands

Treesearch

Neil I. Lamson; Gary W. Miller

1982-01-01

Previously unmanaged 60-year-old, even-aged stands of cherry-maple in West Virginia were thinned using the Allegheny hardwoods stocking guide. A marked cut was computed for 75, 60, and 45 percent of full stocking; no trees smaller than 17.8. cm dbh were marked for commercial removal. Thinning was done with either a truck-mounted crane or a rubber-tired skidder.

A diameter growth model for single-stem growth forms for the interior west forest inventory and analysis’s region

Treesearch

Michael T. Thompson

2015-01-01

The Interior West Forest Inventory and Analysis Unit (IWFIA) will soon transition from a regional system to a national FIA system for compiling estimates of forest growth, removals, and mortality. The national system requires regional diameter-growth models to estimate diameters on trees in situations where the initial or terminal diameter is not known at the beginning...

The significance of sweep in Appalachian hardwood sawlogs

Treesearch

Thomas W., Jr. Church

1973-01-01

Sweep is one of the major stem-form defects in hardwood sawtimber. Some sweep is removed during bucking. But we found sweep of 2 inches or more on 17 percent of the 4,510 logs measured at Appalachian sawmills. Volume deductions for sweep scaled at least 10 percent in 1 of every 7 sample logs and at least 15 percent in 1 of every 9 sample logs. Reduction in the severity...

Five-year growth responses of Douglas-fir, western hemlock, and western redcedar seedlings to manipulated levels of overstory and understory competition.

Treesearch

T.B. Harrington

2006-01-01

Douglas-fir, western hemlock, and western redcedar seedlings were planted in 2001 within clearcuts, shelterwoods, or thinned stands of second-growth Douglas-fir. Understory vegetation was left untreated or removed to provide areas of vegetation control (AVC) of 0, 50, or 100 percent of seedling growing space. Third-year stem volume of seedlings growing in clearcuts...

Yield and Nutrient Removal by Whole-Tree Harvest of a Young Bottomland Hardwood Stand

Treesearch

John K. Francis

1984-01-01

The yield and nutrient withdrawal by whole-tree harvest of young bottomland hardwoods has heretofore been unknown. In this study of intensive harvest, samples of chipped whole trees and soil from 16 test plots were analyzed for nutrient content. Eighty-two percent of the stems and 59 percent of the dry weight were green ash. The balance was divided among a number of...

Stem cell transplantation as rescue therapy for refractory Crohn's disease: a sytematic review.

PubMed

Labidi, Asma; Serghini, Meriem; Ben Mustapha, Nadia; Fekih, Monia; Boubaker, Jalel; Filali, Azza

2014-11-01

Crohn's disease is a chronic relapsing- remitting affection. It has a strong immunologic component which represent the target of standard therapies including immunosppressants and biological therapies. However, many patients remain refracory or intolerant to these therapies. The aim of this review is to determine the effects of stem cell transplantation in patients with refractory Crohn's disease. Systematic review of observational studies, clinical trials and case reports that focused on the effectiveness and safety of stem cell transplantation in patients with refractory Crohn's disease. Hematopoietic stem cell transplantation seems to be efficient in maintaining clinical and endoscopic remission in patients with Crohn's disease refractory or intolerant to current therapies. However, it has been associated to high morbidity and mortality due to chemotherapy. Mesenchymal stem cell transplantation could induce remission in patients with fistulising refractory Crohns disease with no severe side effects. Its impact on luminal Crohns disease is still controversial. Stem cell transplantation seems to hold promising in patients with refractory Crohn's disease. However, because of the high morbidity and mortality related to chemotherapy, hematopoietic stem cell transplantation should be used as last resort to control this disease. Effectiveness of mesenchymal stem cell transplantation in luminal Crohn's disease has yet to be proven.

Impact of biological soil crusts and desert plants on soil microfaunal community composition

USGS Publications Warehouse

Darby, B.J.; Neher, D.A.; Belnap, J.

2010-01-01

Carbon and nitrogen are supplied by a variety of sources in the desert food web; both vascular and non-vascular plants and cyanobacteria supply carbon, and cyanobacteria and plant-associated rhizosphere bacteria are sources of biological nitrogen fixation. The objective of this study was to compare the relative influence of vascular plants and biological soil crusts on desert soil nematode and protozoan abundance and community composition. In the first experiment, biological soil crusts were removed by physical trampling. Treatments with crust removed had fewer nematodes and a greater relative ratio of bacterivores to microphytophages than treatments with intact crust. However, protozoa composition was similar with or without the presence of crusts. In a second experiment, nematode community composition was characterized along a spatial gradient away from stems of grasses or shrubs. Although nematodes generally occurred in increasing abundance nearer to plant stems, some genera (such as the enrichment-type Panagrolaimus) increased disproportionately more than others (such as the stress-tolerant Acromoldavicus). We propose that the impact of biological soil crusts and desert plants on soil microfauna, as reflected in the community composition of microbivorous nematodes, is a combination of carbon input, microclimate amelioration, and altered soil hydrology. ?? Springer Science + Business Media B.V. 2009.

Feedback control in planarian stem cell systems.

PubMed

Mangel, Marc; Bonsall, Michael B; Aboobaker, Aziz

2016-02-13

In planarian flatworms, the mechanisms underlying the activity of collectively pluripotent adult stem cells (neoblasts) and their descendants can now be studied from the level of the individual gene to the entire animal. Flatworms maintain startling developmental plasticity and regenerative capacity in response to variable nutrient conditions or injury. We develop a model for cell dynamics in such animals, assuming that fully differentiated cells exert feedback control on neoblast activity. Our model predicts a number of whole organism level and general cell biological and behaviours, some of which have been empirically observed or inferred in planarians and others that have not. As previously observed empirically we find: 1) a curvilinear relationship between external food and planarian steady state size; 2) the fraction of neoblasts in the steady state is constant regardless of planarian size; 3) a burst of controlled apoptosis during regeneration after amputation as the number of differentiated cells are adjusted towards their homeostatic/steady state level. In addition our model describes the following properties that can inform and be tested by future experiments: 4) the strength of feedback control from differentiated cells to neoblasts (i.e. the activity of the signalling system) and from neoblasts on themselves in relation to absolute number depends upon the level of food in the environment; 5) planarians adjust size when food level reduces initially through increased apoptosis and then through a reduction in neoblast self-renewal activity; 6) following wounding or excision of differentiated cells, different time scales characterize both recovery of size and the two feedback functions; 7) the temporal pattern of feedback controls differs noticeably during recovery from a removal or neoblasts or a removal of differentiated cells; 8) the signaling strength for apoptosis of differentiated cells depends upon both the absolute and relative deviations of the number of differentiated cells from their homeostatic level; and 9) planaria prioritize resource use for cell divisions. We offer the first analytical framework for organizing experiments on planarian flatworm stem cell dynamics in a form that allows models to be compared with quantitative cell data based on underlying molecular mechanisms and thus facilitate the interplay between empirical studies and modeling. This framework is the foundation for studying cell migration during wound repair, the determination of homeostatic levels of differentiated cells by natural selection, and stochastic effects.

Investigation for the differentiation process of mouse ES cells by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Yamaguchi, Yoshinori; El-Hagrasy, Maha A.; Shimizu, Eiichi; Saito, Masato; Tamiya, Eiichi

2012-03-01

The arrangement of differentiated pluripotent embryonic stem cells into three-dimensional aggregates, which are known as embryonic bodies, is a main step for progressing the embryonic stem cells differentiation. In this work, embryonic stem cells that were directly produced from the hanging drop step as a three-dimensional structure with no further twodimensional differentiation were diagnosed with Raman spectroscopy as a non-invasive and label-free technique. Raman spectroscopy was employed to discriminate between mouse embryonic bodies of different degrees of maturation. EBs were prepared applying the hanging drop method. The Raman scattering measurements were obtained in vitro with a Nanophoton RAMAN-11 micro-spectrometer (Japan: URL: www.nanophoton.jp equipped with an Olympus XLUM Plan FLN 20X/NA= 1.0 objective lens. Spectral data were smoothed, baseline corrected and normalized to the a welldefined intense 1003 cm-1 band (phenylalanine) which is insensitive to changes in conformation or environment. The differentiation process of embryonic stem cells is initiated by the removal of LIF from culture medium. 1, 7 and 17-dayold embryonic stem cells were collected and investigated by Raman spectroscopy. The main differences involve bands which decreased with maturation such as: 784 cm-1 (U, T, C ring br DNA/RNA, O-P-O str); 1177 cm-1 (cytosine, guanine) and 1578 cm-1 (G, A). It was found that with the progress of differentiation the protein content was amplified. The increase of protein to nucleic acid ratio was also previously observed with the progress of the differentiation process. Raman spectroscopy has the potential to distinguish between the Raman signatures of live embryonic stem cells with different degrees of maturation.

Periodic harvesting of embryonic stem cells from a hollow-fiber membrane based four-compartment bioreactor.

PubMed

Knöspel, Fanny; Freyer, Nora; Stecklum, Maria; Gerlach, Jörg C; Zeilinger, Katrin

2016-01-01

Different types of stem cells have been investigated for applications in drug screening and toxicity testing. In order to provide sufficient numbers of cells for such in vitro applications a scale-up of stem cell culture is necessary. Bioreactors for dynamic three-dimensional (3D) culture of growing cells offer the option for culturing large amounts of stem cells at high densities in a closed system. We describe a method for periodic harvesting of pluripotent stem cells (PSC) during expansion in a perfused 3D hollow-fiber membrane bioreactor, using mouse embryonic stem cells (mESC) as a model cell line. A number of 100 × 10(6) mESC were seeded in bioreactors in the presence of mouse embryonic fibroblasts (MEF) as feeder cells. Over a cultivation interval of nine days cells were harvested by trypsin perfusion and mechanical agitation every second to third culture day. A mean of 380 × 10(6) mESC could be removed with every harvest. Subsequent to harvesting, cells continued growing in the bioreactor, as determined by increasing glucose consumption and lactate production. Immunocytochemical staining and mRNA expression analysis of markers for pluripotency and the three germ layers showed a similar expression of most markers in the harvested cells and in mESC control cultures. In conclusion, successful expansion and harvesting of viable mESC from bioreactor cultures with preservation of sterility was shown. The present study is the first one showing the feasibility of periodic harvesting of adherent cells from a continuously perfused four-compartment bioreactor including further cultivation of remaining cells. © 2015 American Institute of Chemical Engineers.

Thyroid Hormone‐Induced Activation of Notch Signaling is Required for Adult Intestinal Stem Cell Development During Xenopus Laevis Metamorphosis

PubMed Central

Fujimoto, Kenta; Kajita, Mitsuko; Fu, Liezhen; Shi, Yun‐Bo; Ishizuya‐Oka, Atsuko

2016-01-01

Abstract In Xenopus laevis intestine during metamorphosis, the larval epithelial cells are removed by apoptosis, and the adult epithelial stem (AE) cells appear concomitantly. They proliferate and differentiate to form the adult epithelium (Ep). Thyroid hormone (TH) is well established to trigger this remodeling by regulating the expression of various genes including Notch receptor. To study the role of Notch signaling, we have analyzed the expression of its components, including the ligands (DLL and Jag), receptor (Notch), and targets (Hairy), in the metamorphosing intestine by real‐time reverse transcription‐polymerase chain reaction and in situ hybridization or immunohistochemistry. We show that they are up‐regulated during both natural and TH‐induced metamorphosis in a tissue‐specific manner. Particularly, Hairy1 is specifically expressed in the AE cells. Moreover, up‐regulation of Hairy1 and Hairy2b by TH was prevented by treating tadpoles with a γ‐secretase inhibitor (GSI), which inhibits Notch signaling. More importantly, TH‐induced up‐regulation of LGR5, an adult intestinal stem cell marker, was suppressed by GSI treatment. Our results suggest that Notch signaling plays a role in stem cell development by regulating the expression of Hairy genes during intestinal remodeling. Furthermore, we show with organ culture experiments that prolonged exposure of tadpole intestine to TH plus GSI leads to hyperplasia of secretory cells and reduction of absorptive cells. Our findings here thus provide evidence for evolutionarily conserved role of Notch signaling in intestinal cell fate determination but more importantly reveal, for the first time, an important role of Notch pathway in the formation of adult intestinal stem cells during vertebrate development. Stem Cells 2017;35:1028–1039 PMID:27870267

Peptidoglycan Branched Stem Peptides Contribute to Streptococcus pneumoniae Virulence by Inhibiting Pneumolysin Release

PubMed Central

Greene, Neil G.; Narciso, Ana R.; Filipe, Sergio R.; Camilli, Andrew

2015-01-01

Streptococcus pneumoniae (the pneumococcus) colonizes the human nasopharynx and is a significant pathogen worldwide. Pneumolysin (Ply) is a multi-functional, extracellular virulence factor produced by this organism that is critical for pathogenesis. Despite the absence of any apparent secretion or cell surface attachment motifs, Ply localizes to the cell envelope of actively growing cells. We sought to characterize the consequences of this surface localization. Through functional assays with whole cells and subcellular fractions, we determined that Ply activity and its release into the extracellular environment are inhibited by peptidoglycan (PG) structure. The ability of PG to inhibit Ply release was dependent on the stem peptide composition of this macromolecule, which was manipulated by mutation of the murMN operon that encodes proteins responsible for branched stem peptide synthesis. Additionally, removal of choline-binding proteins from the cell surface significantly reduced Ply release to levels observed in a mutant with a high proportion of branched stem peptides suggesting a link between this structural feature and surface-associated choline-binding proteins involved in PG metabolism. Of clinical relevance, we also demonstrate that a hyperactive, mosaic murMN allele associated with penicillin resistance causes decreased Ply release with concomitant increases in the amount of branched stem peptides. Finally, using a murMN deletion mutant, we observed that increased Ply release is detrimental to virulence during a murine model of pneumonia. Taken together, our results reveal a novel role for branched stem peptides in pneumococcal pathogenesis and demonstrate the importance of controlled Ply release during infection. These results highlight the importance of PG composition in pathogenesis and may have broad implications for the diverse PG structures observed in other bacterial pathogens. PMID:26114646

Peptidoglycan Branched Stem Peptides Contribute to Streptococcus pneumoniae Virulence by Inhibiting Pneumolysin Release.

PubMed

Greene, Neil G; Narciso, Ana R; Filipe, Sergio R; Camilli, Andrew

2015-06-01

Streptococcus pneumoniae (the pneumococcus) colonizes the human nasopharynx and is a significant pathogen worldwide. Pneumolysin (Ply) is a multi-functional, extracellular virulence factor produced by this organism that is critical for pathogenesis. Despite the absence of any apparent secretion or cell surface attachment motifs, Ply localizes to the cell envelope of actively growing cells. We sought to characterize the consequences of this surface localization. Through functional assays with whole cells and subcellular fractions, we determined that Ply activity and its release into the extracellular environment are inhibited by peptidoglycan (PG) structure. The ability of PG to inhibit Ply release was dependent on the stem peptide composition of this macromolecule, which was manipulated by mutation of the murMN operon that encodes proteins responsible for branched stem peptide synthesis. Additionally, removal of choline-binding proteins from the cell surface significantly reduced Ply release to levels observed in a mutant with a high proportion of branched stem peptides suggesting a link between this structural feature and surface-associated choline-binding proteins involved in PG metabolism. Of clinical relevance, we also demonstrate that a hyperactive, mosaic murMN allele associated with penicillin resistance causes decreased Ply release with concomitant increases in the amount of branched stem peptides. Finally, using a murMN deletion mutant, we observed that increased Ply release is detrimental to virulence during a murine model of pneumonia. Taken together, our results reveal a novel role for branched stem peptides in pneumococcal pathogenesis and demonstrate the importance of controlled Ply release during infection. These results highlight the importance of PG composition in pathogenesis and may have broad implications for the diverse PG structures observed in other bacterial pathogens.

Cold-perfusion decellularization of whole-organ porcine pancreas supports human fetal pancreatic cell attachment and expression of endocrine and exocrine markers

PubMed Central

Elebring, Erik; Kuna, Vijay K; Kvarnström, Niclas; Sumitran-Holgersson, Suchitra

2017-01-01

Despite progress in the field of decellularization and recellularization, the outcome for pancreas has not been adequate. This might be due to the challenging dual nature of pancreas with both endocrine and exocrine tissues. We aimed to develop a novel and efficient cold-perfusion method for decellularization of porcine pancreas and recellularize acellular scaffolds with human fetal pancreatic stem cells. Decellularization of whole porcine pancreas at 4°C with sodium deoxycholate, Triton X-100 and DNase efficiently removed cellular material, while preserving the extracellular matrix structure. Furthermore, recellularization of acellular pieces with human fetal pancreatic stem cells for 14 days showed attached and proliferating cells. Both endocrine (C-peptide and PDX1) and exocrine (glucagon and α-amylase) markers were expressed in recellularized tissues. Thus, cold-perfusion can successfully decellularize porcine pancreas, which when recellularized with human fetal pancreatic stem cells shows relevant endocrine and exocrine phenotypes. Decellularized pancreas is a promising biomaterial and might translate to clinical relevance for treatment of diabetes. PMID:29118967

An Elegant Biosensor Molecular Beacon Probe: Challenges and Recent Solutions

PubMed Central

Kolpashchikov, Dmitry M.

2012-01-01

Molecular beacon (MB) probes are fluorophore- and quencher-labeled short synthetic DNAs folded in a stem-loop shape. Since the first report by Tyagi and Kramer, it has become a widely accepted tool for nucleic acid analysis and triggered a cascade of related developments in the field of molecular sensing. The unprecedented success of MB probes stems from their ability to detect specific DNA or RNA sequences immediately after hybridization with no need to wash out the unbound probe (instantaneous format). Importantly, the hairpin structure of the probe is responsible for both the low fluorescent background and improved selectivity. Furthermore, the signal is generated in a reversible manner; thus, if the analyte is removed, the signal is reduced to the background. This paper highlights the advantages of MB probes and discusses the approaches that address the challenges in MB probe design. Variations of MB-based assays tackle the problem of stem invasion, improve SNP genotyping and signal-to-noise ratio, as well as address the challenges of detecting folded RNA and DNA. PMID:24278758

Stimulatory effect of icariin on the proliferation of neural stem cells from rat hippocampus.

PubMed

Fu, Xiaolong; Li, Shujun; Zhou, Shaoyu; Wu, Qin; Jin, Feng; Shi, Jingshan

2018-01-29

Icariin (ICA), a major ingredient of Epimediumbrevicornum, has various pharmacological activities including central nervous system protective functions such as the improvement of learning and memory function in mice models of Alzheimer's disease. It has been reported that ICA can promote regeneration of peripheral nerve and functional recovery. The purpose of this study was to investigate the potentiating effect of ICA on the proliferation of rat hippocampal neural stem cells, and explore the possible mechanism involved. Primary neural stem cells were prepared from the hippocampus of newly born SD rats, and cells were cultured in special stem cell culture medium. Neural stem cells were confirmed by immunofluorescence detection of nestin, NSE and GFAP expression. The effect of ICA on the growth and proliferation of the neural stem cells was evaluated by 5-ethynyl-2-deoxyuridine (EdU) labeling of proliferating cells, and photomicrographic images of the cultured neural stem cells. Further, the mechanism of ICA-induced cell proliferation of neural stem cells was investigated by analyzing the gene and protein expression of cell cycle related genes cyclin D1 and p21. The present study showed that icariin promotes the growth and proliferation of neural stem cells from rat hippocampus in a dose-dependent manner. Incubation of cells with icariin resulted in significant increase in the number of stem cell spheres as well as the increased incorporation of EdU when compared with cells exposed to control vehicle. In addition, it was found that icariin-induced effect on neural stem cells is associated with increased mRNA and protein expression of cell cycle genes cyclin D1 and p21. This study evidently demonstrates the potentiating effect of ICA on neural stem cell growth and proliferation, which might be mediated through regulation of cell cycle gene and protein expression promoting cell cycle progression.

Fruit production in cranberry (Ericaceae: Vaccinium macrocarpon): a bet-hedging strategy to optimize reproductive effort.

PubMed

Brown, Adam O; McNeil, Jeremy N

2006-06-01

In the cultivated cranberry (Vaccinium macrocarpon), reproductive stems produce 1-3 fruit even though they usually have 5-7 flowers in the spring. We undertook experiments to test the hypothesis that this was an adaptive life history strategy associated with reproductive effort rather than simply the result of insufficient pollination. We compared fruit production on naturally pollinated plants with those that were either manually pollinated or that were caged to exclude insects. Clearly, insects are necessary for the effective pollination of cranberry plants, but hand pollination of all flowers did not result in an increase in fruit number. Most of the upper flowers, which had significantly fewer ovules than did the lower flowers, aborted naturally soon after pollination. However, when the lower flower buds were removed, the upper flowers produced fruit. This suggests that the upper flowers may serve as a backup if the earlier blooming lower ones are lost early in the season. Furthermore, the late-blooming flowers may still contribute to the plant's reproductive success as visiting pollinators remove the pollen, which could serve to sire fruit on other plants. These results are discussed in the context of their possible evolutionary and proximate causes.

Inhibition of glycogen synthase kinase 3 increased subventricular zone stem cells proliferation.

PubMed

Pachenari, Narges; Kiani, Sahar; Javan, Mohammad

2017-09-01

The effects of Wnt signaling modifiers on cell proliferation, seem to be cell specific. Enhancing the proliferation of subventricular zone (SVZ) progenitors has been in the focus of research in recent years. Here we investigate the effect of CHIR99021, a Glycogen Synthase Kinase 3 (GSk-3) inhibitor, on SVZ progenitor's proliferation both in vivo and in vitro. Neural stem cells were extracted from the adult C57bl/6 by mincing and trypsin treatment followed by culturing in specific medium. Sphere cells formed within about 7-10days and were characterized by immunostaining. Number of spheres and their size was assessed following exposure to different concentration of CHIR99021 or vehicle. For in vivo studies, animals received intracerebroventricular (i.c.v.) injection of CHIR99021 or vehicle for four days. A subgroup of animals, after 4days treatment with CHIR99021 received intranasal kainic acid to induce local neurodegeneration in CA3 area of hippocampus. Inhibition of GSk-3 by CHIR99021 increased neural progenitor proliferation and the effect of CHIR99021 was long lasting so that the treated cells showed higher proliferation even after CHIR99021 removal. In vivo administration of CHIR99021 increased the number of neural progenitors at the rims of lateral ventricles especially when the treatment was followed by kainic acid administration which induces neural insult. Results showed that direct administration of CHIR99021 into the culture medium or animal brain increased the number of SVZ progenitors, especially when a neural insult was induced in the hippocampus. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Tree CH4 fluxes in forestry drained peatland in southern Finland

NASA Astrophysics Data System (ADS)

Haikarainen, Iikka; Putkinen, Anuliina; Pyykkö, Petteri; Halmeenmäki, Elisa; Pihlatie, Mari

2017-04-01

Methane (CH4) is among the most important greenhouse gases and its atmospheric concentration is increasing. Boreal forests are commonly considered a net sink of atmospheric CH4 due to CH4 consuming bacteria in aerated soil layers. Recent studies have, however, demonstrated that trees are capable of emitting CH4 from their stems and shoots by transporting anaerobically produced CH4 from deeper soil layers to the atmosphere. Furthermore, trees may act as independent sources of CH4. We have measured tree stem CH4 exchange of boreal tree species at Lettosuo, a nutrient rich peatland forest in Tammela, southern Finland (60˚ 38' N, 23˚ 57' E), using the static chamber technique. Three species, downy birch (Betula pubescens), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris), were selected under investigation as they represent common boreal tree species. Fluxes of CH4 were measured during 7.6.2016 - 17.10.2016 from in total 25 sample trees growing on two different plots: a treatment plot where all the pines were removed to raise the water table level (WTL) and a control plot. Three birches from the treatment plot were selected to measure CH4 flux variation within vertical profile of the trees. Characterization of microbial communities, quantification of methanogenic and methanotrophic functional genes, and measurements of potential CH4 production and consumption from peat profile and forest floor moss samples were also carried out to obtain insight to the CH4 flux dynamics at the studied sites. The pine removal treatment did not markedly change the average WTL, but it made the WTL more variable with frequently 10-15 cm closer to soil surface compared to the WTL on the control plot. We found small and variable CH4 emissions from the stems of trees on both of the plots, while occasional consumption of CH4 was also present. Generally the CH4 emissions were higher and more dominant at the treatment plot compared to the control plot, and the fluxes were significantly different between the plots (p < 0.001). The CH4 emission rates from the birches at the treatment plot decreased exponentially in the stem vertical profile. Clear seasonal flux dynamics or significant differences in the CH4 flux between the species were not found at either of the plots. Microbial experiments showed that anaerobic CH4 production, CH4 oxidation potential (under 1000 ppm CH4) and the amount of methanogens were higher in the peat of the treatment site. The difference in the CH4 flux rates between the plots indicates that the WTL is a major regulator of tree CH4 emissions on forestry drained peatlands, supporting our hypothesis that the stem emitted CH4 originates from anaerobic soil conditions. This hypothesis is further supported by the results of the microbial analysis and by the observation that more CH4 is emitting from the lower parts of the stems compared to the upper stem.

Effect of wheat stem sawfly damage on yield and quality of selected Canadian spring wheat.

PubMed

Beres, B L; Cárcamo, H A; Byers, J R

2007-02-01

The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), has reached outbreak status at most locations in the southern Canadian prairies. Solid-stemmed wheat, Triticum aestivum L., cultivars, which are less susceptible to damage, remain the primary management option. This article quantifies the effect of wheat stem sawfly damage on grain yield and quality at harvest and determines how cultivar selection affects harvest losses. Solid-stemmed cultivars were compared with hollow-stemmed cultivars and with blends of a 1:1 ratio of each. The hollow-stemmed cultivars with the exception of'McKenzie', which had intermediate levels of stem cutting, were all significantly more susceptible to stem cutting than solid-stemmed cultivars. Cultivar blends had lower damage but were still significantly higher than the solid-stemmed cultivars. The solid-stemmed 'AC Eatonia' and 'AC Abbey' had the lowest levels of stem cutting and ranked second and third overall for yield in 2001 and 2002. McKenzie ranked first, which reflects its yield potential in combination with its partial resistance to stem cutting. Lower cutting in AC Eatonia, AC Abbey, McKenzie, and the blend of AC Abbey/ McKenzie was significantly correlated with lower grain losses. Grain lost at harvest has major economic implications if sawfly pressure is moderate to high and susceptible cultivars predominate.

Stem photosynthesis and hydraulics are coordinated in desert plant species.

PubMed

Ávila-Lovera, Eleinis; Zerpa, Antonio J; Santiago, Louis S

2017-12-01

Coordination between stem photosynthesis and hydraulics in green-stemmed desert plants is important for understanding the physiology of stem photosynthesis and possible drought responses. Plants with photosynthetic stems have extra carbon gain that can help cope with the detrimental effects of drought. We studied photosynthetic, hydraulic and functional traits of 11 plant species with photosynthetic stems from three California desert locations. We compared relationships among traits between wet and dry seasons to test the effect of seasonality on these relationships. Finally, we compared stem trait relationships with analogous relationships in the leaf economics spectrum. We found that photosynthetic and hydraulic traits are coordinated in photosynthetic stems. The slope or intercept of all trait relationships was mediated by seasonality. The relationship between mass-based stem photosynthetic CO 2 assimilation rate (A mass ) and specific stem area (SSA; stem surface area to dry mass ratio) was statistically indistinguishable from the leaf economics spectrum. Our results indicate that photosynthetic stems behave like leaves in the coordination of multiple traits related to carbon gain, water movement and water loss. Because of the similarity of the stem A mass -SSA relationship to the leaf A mass -specific leaf area relationship, we suggest the existence of a photosynthetic stem economic spectrum. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Interference-free Micro/nanoparticle Cell Engineering by Use of High-Throughput Microfluidic Separation.

PubMed

Yeo, David C; Wiraja, Christian; Zhou, Yingying; Tay, Hui Min; Xu, Chenjie; Hou, Han Wei

2015-09-23

Engineering cells with active-ingredient-loaded micro/nanoparticles is becoming increasingly popular for imaging and therapeutic applications. A critical yet inadequately addressed issue during its implementation concerns the significant number of particles that remain unbound following the engineering process, which inadvertently generate signals and impart transformative effects onto neighboring nontarget cells. Here we demonstrate that those unbound micro/nanoparticles remaining in solution can be efficiently separated from the particle-labeled cells by implementing a fast, continuous, and high-throughput Dean flow fractionation (DFF) microfluidic device. As proof-of-concept, we applied the DFF microfluidic device for buffer exchange to sort labeled suspension cells (THP-1) from unbound fluorescent dye and dye-loaded micro/nanoparticles. Compared to conventional centrifugation, the depletion efficiency of free dyes or particles was improved 20-fold and the mislabeling of nontarget bystander cells by free particles was minimized. The microfluidic device was adapted to further accommodate heterogeneous-sized mesenchymal stem cells (MSCs). Complete removal of unbound nanoparticles using DFF led to the usage of engineered MSCs without exerting off-target transformative effects on the functional properties of neighboring endothelial cells. Apart from its effectiveness in removing free particles, this strategy is also efficient and scalable. It could continuously process cell solutions with concentrations up to 10(7) cells·mL(-1) (cell densities commonly encountered during cell therapy) without observable loss of performance. Successful implementation of this technology is expected to pave the way for interference-free clinical application of micro/nanoparticle engineered cells.

Weakening of negative relative to positive associations with cocaine-paired cues contributes to cue-induced responding after drug removal.

PubMed

Su, Zu-In; Kichaev, Gleb; Wenzel, Jennifer; Ben-Shahar, Osnat; Ettenberg, Aaron

2012-01-01

Cocaine has been shown to have initial positive (euphoric) and delayed negative (anxiogenic) effects in both humans and animals. Cocaine-paired cues are consequently imbued with mixed positive and negative associations. The current study examines the relative roles of these dual associations in the enhanced drug-seeking observed upon presentation of cocaine-paired cues. Rats ran a straight alley once/day for a single i.v. injection of cocaine (1.0 mg/kg/inj) in the presence of a distinctive olfactory cue (scented cotton swabs placed under the apparatus). An alternate scent was presented in a separate cage 2-h prior to runway testing. After 15 trials/days, the scents and cocaine reinforcer were removed and a series of extinction trials (lasting for 1 or 3 weeks) was initiated. Immediately following extinction, runway responding was tested during a single trial in the presence of the cocaine-paired or non-paired cue. As previously reported, while subjects initiated responding faster over trials (reduced latencies to leave the start box), they exhibited a progressive increase in approach-avoidance conflict behavior ("retreats") regarding goal-box entry, reflecting cocaine's dual positive+negative effects. Once established, retreat behaviors persisted over the course of 1 or 3 weeks days of extinction. However, both run times and retreats decreased in response to presentation of the cocaine-paired but not the non-paired scent. These data suggest that, after reinforcer removal, cue-induced cocaine-seeking stems in part from a reduction in approach-avoidance conflict; i.e., a greater weakening of the negative relative to the positive associations that animals form with cocaine-paired stimuli. Copyright © 2011 Elsevier Inc. All rights reserved.

Computational fluid dynamics-habitat suitability index (CFD-HSI) modelling as an exploratory tool for assessing passability of riverine migratory challenge zones for fish

USGS Publications Warehouse

Haro, Alexander J.; Chelminski, Michael; Dudley, Robert W.

2015-01-01

We developed two-dimensional computational fluid hydraulics-habitat suitability index (CFD-HSI) models to identify and qualitatively assess potential zones of shallow water depth and high water velocity that may present passage challenges for five major anadromous fish species in a 2.63-km reach of the main stem Penobscot River, Maine, as a result of a dam removal downstream of the reach. Suitability parameters were based on distribution of fish lengths and body depths and transformed to cruising, maximum sustained and sprint swimming speeds. Zones of potential depth and velocity challenges were calculated based on the hydraulic models; ability of fish to pass a challenge zone was based on the percent of river channel that the contiguous zone spanned and its maximum along-current length. Three river flows (low: 99.1 m3 sec-1; normal: 344.9 m3 sec-1; and high: 792.9 m3 sec-1) were modelled to simulate existing hydraulic conditions and hydraulic conditions simulating removal of a dam at the downstream boundary of the reach. Potential depth challenge zones were nonexistent for all low-flow simulations of existing conditions for deeper-bodied fishes. Increasing flows for existing conditions and removal of the dam under all flow conditions increased the number and size of potential velocity challenge zones, with the effects of zones being more pronounced for smaller species. The two-dimensional CFD-HSI model has utility in demonstrating gross effects of flow and hydraulic alteration, but may not be as precise a predictive tool as a three-dimensional model. Passability of the potential challenge zones cannot be precisely quantified for two-dimensional or three-dimensional models due to untested assumptions and incomplete data on fish swimming performance and behaviours.

Bromelain treatment decreases neutrophil migration to sites of inflammation.

PubMed

Fitzhugh, David J; Shan, Siqing; Dewhirst, Mark W; Hale, Laura P

2008-07-01

Bromelain, a mixture of proteases derived from pineapple stem, has been reported to have therapeutic benefits in a variety of inflammatory diseases, including murine inflammatory bowel disease. The purpose of this work was to understand potential mechanisms for this anti-inflammatory activity. Exposure to bromelain in vitro has been shown to remove a number of cell surface molecules that are vital to leukocyte trafficking, including CD128a/CXCR1 and CD128b/CXCR2 that serve as receptors for the neutrophil chemoattractant IL-8 and its murine homologues. We hypothesized that specific proteolytic removal of CD128 molecules by bromelain would inhibit neutrophil migration to IL-8 and thus decrease acute responses to inflammatory stimuli. Using an in vitro chemotaxis assay, we demonstrated a 40% reduction in migration of bromelain- vs. sham-treated human neutrophils in response to rhIL-8. Migration to the bacterial peptide analog fMLP was unaffected, indicating that bromelain does not induce a global defect in leukocyte migration. In vivo bromelain treatment generated a 50-85% reduction in neutrophil migration in 3 different murine models of leukocyte migration into the inflamed peritoneal cavity. Intravital microscopy demonstrated that although in vivo bromelain treatment transiently decreased leukocyte rolling, its primary long-term effect was abrogation of firm adhesion of leukocytes to blood vessels at the site of inflammation. These changes in adhesion were correlated with rapid re-expression of the bromelain-sensitive CD62L/L-selectin molecules that mediate rolling following in vivo bromelain treatment and minimal re-expression of CD128 over the time period studied. Taken together, these studies demonstrate that bromelain can effectively decrease neutrophil migration to sites of acute inflammation and support the specific removal of the CD128 chemokine receptor as a potential mechanism of action.

Bromelain Treatment Decreases Neutrophil Migration to Sites of Inflammation

PubMed Central

Fitzhugh, David J.; Shan, Siqing; Dewhirst, Mark W.; Hale, Laura P.

2008-01-01

Bromelain, a mixture of proteases derived from pineapple stem, has been reported to have therapeutic benefits in a variety of inflammatory diseases, including murine inflammatory bowel disease. The purpose of this work was to understand potential mechanisms for this anti-inflammatory activity. Exposure to bromelain in vitro has been shown to remove a number of cell surface molecules that are vital to leukocyte trafficking, including CD128a/CXCR1 and CD128b/CXCR2 that serve as receptors for the neutrophil chemoattractant IL-8 and its murine homologues. We hypothesized that specific proteolytic removal of CD128 molecules by bromelain would inhibit neutrophil migration to IL-8 and thus decrease acute responses to inflammatory stimuli. Using an in vitro chemotaxis assay, we demonstrated a 40% reduction in migration of bromelain- vs. sham-treated human neutrophils in response to rhIL-8. Migration to the bacterial peptide analog fMLP was unaffected, indicating that bromelain does not induce a global defect in leukocyte migration. In vivo bromelain treatment generated a 50 – 85% reduction in neutrophil migration in 3 different murine models of leukocyte migration into the inflamed peritoneal cavity. Intravital microscopy demonstrated that although in vivo bromelain treatment transiently decreased leukocyte rolling, its primary long-term effect was abrogation of firm adhesion of leukocytes to blood vessels at the site of inflammation. These changes in adhesion were correlated with rapid re-expression of the bromelain-sensitive CD62L/L-selectin molecules that mediate rolling following in vivo bromelain treatment and minimal re-expression of CD128 over the time period studied. Taken together, these studies demonstrate that bromelain can effectively decrease neutrophil migration to sites of acute inflammation and support the specific removal of the CD128 chemokine receptor as a potential mechanism of action. PMID:18482869

The Barberry Eradication Program in Minnesota for Stem Rust Control: A Case Study.

PubMed

Peterson, Paul D

2018-06-11

The Barberry Eradication Program was an unprecedented federal and state cooperative plant disease control campaign between 1918 and the late 1970s to remove common barberry (Berberis vulgaris), the alternate host of Puccinia graminis f. sp. tritici, from the major centers of wheat production in the United States. Eradication of barberry has been credited with helping to reduce stem rust of wheat to a minor problem in the United States by the end of the campaign. The Barberry Eradication Program has also been viewed as a model for successful eradication based on its robust leadership, effective publicity and public cooperation, forceful quarantine laws, and adaptive eradication methods and procedures employed in its field operations. The Barberry Eradication Program was particularly successful because of its leaders' ability to adapt to changing internal and external conditions over time. The program lasted nearly a century, extending through two world wars and the Great Depression, with each period producing unique challenges. Because of its central role, barberry eradication in Minnesota offers an excellent case study to examine how the program developed over time and ultimately achieved success. Expected final online publication date for the Annual Review of Phytopathology Volume 56 is August 25, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Phyto-enhanced remediation of soil co-contaminated with lead and diesel fuel using biowaste and Dracaena reflexa: A laboratory study.

PubMed

Dadrasnia, Arezoo; Pariatamby, Agamuthu

2016-03-01

In phytoremediation of co-contaminated soil, the simultaneous and efficient remediation of multiple pollutants is a major challenge rather than the removal of pollutants. A laboratory-scale experiment was conducted to investigate the effect of 5% addition of each of three different organic waste amendments (tea leaves, soy cake, and potato skin) to enhance the phytoaccumulation of lead (60 mg kg(-1)) and diesel fuel (25,000 mg kg(-1)) in co-contaminated soil by Dracaena reflexa Lam for a period of 180 day. The highest rate of oil degradation was recorded in co-contaminated soil planted with D. reflexa and amended with soy cake (75%), followed by potato skin (52.8%) and tea leaves (50.6%). Although plants did not accumulate hydrocarbon from the contaminated soil, significant bioaccumulation of lead in the roots and stems of D. reflexa was observed. At the end of 180 days, 16.7 and 9.8 mg kg(-1) of lead in the stems and roots of D. reflexa were recorded, respectively, for the treatment with tea leaves. These findings demonstrate the potential of organic waste amendments in enhancing phytoremediation of oil and bioaccumulation of lead. © The Author(s) 2015.

Centerless grinding of TiAl using conventional grinding wheels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, P.E.; Smits, D.; Eylon, D.

1995-12-31

Ordered gamma titanium aluminide (TiAl) based alloys are now under consideration for automotive valves because of their light weight and high strength at temperatures up to 850 C. Finishing comprises as much as 70% of the cost of an automotive valve, therefore the grindability of TiAl valves will influence their commercial viability. This study compared the grindability of the TiAl alloy Ti-47Al-2Nb-1.75Cr (at%) to standard valve steels, nickel base superalloys, and conventional titanium alloys using the centerless grinding process. Three grinding conditions simulating stem grinding were selected. The power requirements, grinding time, and grinding wheel consumption were used to estimatemore » the cost to grind TiAl on conventional centerless grinding equipment using vitrified bonded silicon carbide wheels. The metallurgical effects of rough and finish stem grinding cycles on the surface were determined. The grindability factor of TiAl, a measure of grinding cost, was slightly inferior to conventional valve steels, but much better than conventional titanium alloys. The high work hardening rate of the TiAl resulted in much better surface finish at high metal removal rates than that achieved in steels. No grinding cracks were observed, even under the rough grinding conditions. Microhardness profiles indicated significant work hardening of the surface under all three grinding conditions.« less

An individual-based growth and competition model for coastal redwood forest restoration

USGS Publications Warehouse

van Mantgem, Phillip J.; Das, Adrian J.

2014-01-01

Thinning treatments to accelerate coastal redwood forest stand development are in wide application, but managers have yet to identify prescriptions that might best promote Sequoia sempervirens (Lamb. ex D. Don) Endl. (redwood) growth. The creation of successful thinning prescriptions would be aided by identifying the underlying mechanisms governing how individual tree growth responds to competitive environments in coastal redwood forests. We created a spatially explicit individual-based model of tree competition and growth parameterized using surveys of upland redwood forests at Redwood National Park, California. We modeled competition for overstory trees (stems ≥ 20 cm stem diameter at breast height, 1.37 m (dbh)) as growth reductions arising from sizes, distances, and species identity of competitor trees. Our model explained up to half of the variation in individual tree growth, suggesting that neighborhood crowding is an important determinant of growth in this forest type. We used our model to simulate the effects of novel thinning prescriptions (e.g., 40% stand basal area removal) for redwood forest restoration, concluding that these treatments could lead to substantial growth releases, particularly for S. sempervirens. The results of this study, along with continued improvements to our model, will help to determine spacing and species composition that best encourage growth.

Pathway to a Baccalaureate in STEM Fields: Community Colleges a Viable Route and Does Early STEM Momentum Matter?

ERIC Educational Resources Information Center

Wang, Xueli

2015-01-01

This study examines the effect of beginning at a community college on baccalaureate success in science, technology, engineering, and mathematics (STEM) fields. In addition, drawing upon a new concept of "STEM momentum," this research explores whether and how STEM baccalaureate success is related to early STEM momentum, as well as whether…

Antitumor Activity of Rat Mesenchymal Stem Cells during Direct or Indirect Co-Culturing with C6 Glioma Cells.

PubMed

Gabashvili, A N; Baklaushev, V P; Grinenko, N F; Mel'nikov, P A; Cherepanov, S A; Levinsky, A B; Chehonin, V P

2016-02-01

The tumor-suppressive effect of rat mesenchymal stem cells against low-differentiated rat C6 glioma cells during their direct and indirect co-culturing and during culturing of C6 glioma cells in the medium conditioned by mesenchymal stem cells was studied in an in vitro experiment. The most pronounced antitumor activity of mesenchymal stem cells was observed during direct co-culturing with C6 glioma cells. The number of live C6 glioma cells during indirect co-culturing and during culturing in conditioned medium was slightly higher than during direct co-culturing, but significantly differed from the control (C6 glioma cells cultured in medium conditioned by C6 glioma cells). The cytotoxic effect of medium conditioned by mesenchymal stem cells was not related to medium depletion by glioma cells during their growth. The medium conditioned by other "non-stem" cells (rat astrocytes and fibroblasts) produced no tumor-suppressive effect. Rat mesenchymal stem cells, similar to rat C6 glioma cells express connexin 43, the main astroglial gap junction protein. During co-culturing, mesenchymal stem cells and glioma C6 cells formed functionally active gap junctions. Gap junction blockade with connexon inhibitor carbenoxolone attenuated the antitumor effect observed during direct co-culturing of C6 glioma cells and mesenchymal stem cells to the level produced by conditioned medium. Cell-cell signaling mediated by gap junctions can be a mechanism of the tumor-suppressive effect of mesenchymal stem cells against C6 glioma cells. This phenomenon can be used for the development of new methods of cell therapy for high-grade malignant gliomas.

Stem Cell Sciences plc.

PubMed

Daniels, Sebnem

2006-09-01

Stem Cell Sciences' core objective is to develop safe and effective stem cell-based therapies for currently incurable diseases. In order to achieve this goal, Stem Cell Sciences recognizes the need for multiple technologies and a globally integrated stem cell initiative. The key challenges for the successful application of stem cells in the clinic is the need for a reproducible supply of pure, fully characterized stem cells that have been grown in suitable conditions for use in the clinic.

Hepatocyte Growth Factor Gene-Modified Mesenchymal Stem Cells Augment Sinonasal Wound Healing

PubMed Central

Li, Jing; Li, Yong; Yang, Chen; Lin, Hai; Duan, Hong-Gang

2015-01-01

This study was designed to investigate the effects of hepatocyte growth factor (HGF) transgenic mesenchymal stem cells (HGF-MSCs) on wound healing in the sinonasal mucosa and nasal epithelial cells (NECs). We also sought to determine whether HGF-MSCs and MSCs can migrate into the injured mucosa and differentiate into ciliated cells. Human HGF-overexpressing umbilical cord MSCs (hHGF-UCMSCs) were established, and upregulation of hHGF expression was confirmed by real-time PCR (RT-PCR) and enzyme-linked immunosorbant assay (ELISA). To investigate the paracrine effect of human MSCs (hMSCs) on nasal epithelial repair, hMSC- and HGF-MSC-conditioned media (CM) were used in NEC proliferation assays and in an in vitro scratch-wound repair model. The in vivo sinonasal wound-healing model was established, and all enrolled rabbits were randomly assigned to four groups: the GFP-MSC group, the HGF-MSC group, the Ad-HGF group, and the surgery control group. The average decreased diameter was recorded, and the medial wall of the maxillary sinus was removed for histological analysis and scanning electron microscopy. Collagen deposition in the wound tissue was detected via Masson trichrome (M&T) staining. The distribution of MSCs and HGF-MSCs was observed by immunofluorescence. MSCs improved nasal wound healing both in vivo and in vitro. HGF overexpression in MSCs augmented the curative effects. Reduced collagen deposition and transforming growth factor beta1 (TGF-β1) expression were detected in the HGF-MSC group compared with the MSC-, Ad-HGF-, and phosphate-buffered saline-treated groups based on M&T staining and ELISA. The enhanced therapeutic effects of HGF-MSCs were accompanied by decreased level of the fibrogenic cytokine TGF-β1. In addition, both HGF-MSCs and MSCs can migrate to the injured mucosa and epithelial layer. PMID:25835956

Hepatocyte Growth Factor Gene-Modified Mesenchymal Stem Cells Augment Sinonasal Wound Healing.

PubMed

Li, Jing; Zheng, Chun-Quan; Li, Yong; Yang, Chen; Lin, Hai; Duan, Hong-Gang

2015-08-01

This study was designed to investigate the effects of hepatocyte growth factor (HGF) transgenic mesenchymal stem cells (HGF-MSCs) on wound healing in the sinonasal mucosa and nasal epithelial cells (NECs). We also sought to determine whether HGF-MSCs and MSCs can migrate into the injured mucosa and differentiate into ciliated cells. Human HGF-overexpressing umbilical cord MSCs (hHGF-UCMSCs) were established, and upregulation of hHGF expression was confirmed by real-time PCR (RT-PCR) and enzyme-linked immunosorbant assay (ELISA). To investigate the paracrine effect of human MSCs (hMSCs) on nasal epithelial repair, hMSC- and HGF-MSC-conditioned media (CM) were used in NEC proliferation assays and in an in vitro scratch-wound repair model. The in vivo sinonasal wound-healing model was established, and all enrolled rabbits were randomly assigned to four groups: the GFP-MSC group, the HGF-MSC group, the Ad-HGF group, and the surgery control group. The average decreased diameter was recorded, and the medial wall of the maxillary sinus was removed for histological analysis and scanning electron microscopy. Collagen deposition in the wound tissue was detected via Masson trichrome (M&T) staining. The distribution of MSCs and HGF-MSCs was observed by immunofluorescence. MSCs improved nasal wound healing both in vivo and in vitro. HGF overexpression in MSCs augmented the curative effects. Reduced collagen deposition and transforming growth factor beta1 (TGF-β1) expression were detected in the HGF-MSC group compared with the MSC-, Ad-HGF-, and phosphate-buffered saline-treated groups based on M&T staining and ELISA. The enhanced therapeutic effects of HGF-MSCs were accompanied by decreased level of the fibrogenic cytokine TGF-β1. In addition, both HGF-MSCs and MSCs can migrate to the injured mucosa and epithelial layer.

Stem cells and regenerative medicine: principles, prospects and problems.

PubMed

Gardner, Richard L

2007-01-01

Stem cells have been used routinely for more than three decades to repair tissues and organs damaged by injury or disease, most notably haematopoietic stem cells taken from bone marrow, umbilical cord or, increasingly, from peripheral blood. Other examples, such as grafts of skin to treat severe burns, entail transplantation of stem cells within organized tissue rather than following isolation. The prospect of exploiting stem cells more widely in regenerative medicine was encouraged both by the development of human assisted conception and growing evidence that various adult cells retained greater versatility than had been suspected hitherto. The aim is to employ stem cells as a source of appropriately differentiated cells to replace those lost through physical, chemical or ischaemic injury, or as a result of degenerative disease. This may entail transplantation of just a single type of cell or, more challengingly, require a complex of several different types of cells possessing a defined architecture. Cardiomyocytes, hepatocytes or neuronal cells producing specific transmitters offer promising examples of the former, although how transplanted healthy cells will function in a perturbed tissue environment remains to be established. Recent success in repairing urinary bladder defects with grafts of urothelial and muscle cells seeded on a biodegradable collagen scaffold is an encouraging step towards assembling organs in vitro. Nevertheless, this is still far removed from the level of sophistication required to counter the ever increasing shortfall in supply of kidneys for transplantation. Various problems must be addressed if recent advances in the laboratory are to be translated into clinical practice. In many cases, it has yet to be established that cells derived from adults that retain plasticity are actually stem cells. There is also a pressing need for appropriate assays to ensure that, regardless of source, stem cells maintained in vitro are safe to transplant. Assays currently available for human ES cells are far from ideal. It is, in addition, important to ensure that differentiated cultures are pure and, depending on whether cell renewal is required or to be avoided, retain or lack appropriate stem cells. Neither autografts nor those obtained by so-called 'therapeutic cloning' are options for treating condition with an obvious genetic basis. Moreover, claims that some stem cells are more likely than others to yield successful allografts have yet to be confirmed and explained.

Mesenchymal Stem Cells Derived from Human Limbal Niche Cells

PubMed Central

Li, Gui-Gang; Zhu, Ying-Ting; Xie, Hua-Tao; Chen, Szu-Yu; Tseng, Scheffer C. G.

2012-01-01

Purpose. We investigated whether human limbal niche cells generate mesenchymal stem cells. Methods. Limbal niche cells were isolated from the limbal stroma by collagenase alone or following dispase removal of the limbal epithelium (D/C), and cultured on plastic in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS), or coated or three-dimensional Matrigel in embryonic stem cell medium with leukemia inhibitory factor and basic fibroblast growth factor. Expression of cell markers, colony-forming units-fibroblast, tri-lineage differentiation, and ability of supporting limbal epithelial stem/progenitor cells were compared to limbal residual stromal cells. Results. Stromal cells expressing angiogenesis markers were found perivascularly, subjacent to limbal basal epithelial cells, and in D/C and limbal residual stromal cells. When seeded in three-dimensional Matrigel, D/C but not limbal residual stromal cells yielded spheres of angiogenesis progenitors that stabilized vascular networks. Similar to collagenase-isolated cells, D/C cells could be expanded on coated Matrigel for more than 12 passages, yielding spindle cells expressing angiogenesis and mesenchymal stem cells markers, and possessing significantly higher colony-forming units-fibroblast and more efficient tri-lineage differentiation than D/C and limbal residual stromal cells expanded on plastic in DMEM with 10% FBS, of which both lost the pericyte phenotype while limbal residual stromal cells turned into myofibroblasts. Upon reunion with limbal epithelial stem/progenitor cells to form spheres, D/C cells expanded on coated Matrigel maintained higher expression of p63α and lower expression of cytokeratin 12 than those expanded on plastic in DMEM with 10% FBS, while spheres formed with human corneal fibroblasts expressed cytokeratin 12 without p63α. Conclusions. In the limbal stroma, cells subjacent to limbal basal epithelial cells serve as niche cells, and generate progenitors with angiogenesis and mesenchymal stem cells potentials. They might partake in angiogenesis and regeneration during corneal wound healing. PMID:22836771

The involvement of ethylene in regulation of Arabidopsis gravitropism

NASA Astrophysics Data System (ADS)

Li, Ning; Zhu, Lin

Plant gravitropism is a directional response to gravity stimulus. This response involves a com-plex signaling network. Ethylene, a major plant hormone, has been found to modulate grav-itropism. The biosynthesis of ethylene is induced by the gravi-stimulus and the requirement for ethylene during gravitropism is tissue-dependent. While ethylene plays a modulating role in inflorescence stems, the light-grown hypocotyls of Arabidopsis requires ethylene to achieve a maximum gravicurvature. Because both inhibitory and stimulatory effects of ethylene on gravitropism have been overwhelmingly documented, there is a need to postulate a new theory to consolidate the apparently contradictory results. A dual-and-opposing effects (DOE) theory is therefore hypothesized to address how ethylene is involved in regulation of Arabidopsis grav-itropism, in which it is suggested that both stimulatory and inhibitory effects act on the same organ of a plant and co-exist at the same time in a mutually opposing manner. The final out-come of gravitropic response is determined by the dynamic display between the two opposing effects. A prolonged pretreatment of ethylene promotes the gravitropism in both inflorescence and light-grown hypocotyls, while a short ethylene pretreatment inhibits gravitropism. Gener-ally speaking, the inhibitory effect of ethylene is dominant over the expression of the stimula-tory effect in light-grown hypocotyls, whereas the stimulatory effect is dominant in inflorescence stem. Each effect is also positively correlated with concentrations of ethylene and in a time-dependent manner. The stimulatory effect occurs slowly but continues to react after the removal of ethylene, whereas the inhibitory effect takes place abruptly and diminishes shortly after its removal. Forward genetic screening based on the DOE phenotype of ethylene-treated Arabidop-sis has revealed a novel component in gravity signaling pathway: EGY1 (ethylene-dependent gravitropism-deficient and yellow green 1, Chen et al 2005; Guo et al 2008). To address the molecular mechanism by which ethylene regulates gravitropism, a cutting-edge phosphopro-teomics approach has been adopted to discover new components involved in ethylene signaling pathways (Li et al 2009). Two putative ethylene response transcription factors: EIL1 and ERF110, have been identified to contain ethylene-regulated phosphorylation sites, the phos-phorylation status of which are ethylene treatment-dependent but EIN2-independent, strongly suggestive of the existence of novel signaling components mediating an alternative ethylene signal pathway. Combination of the time-dependent ethylene treatments with the systematic profiling of protein phosphorylation using functional phosphoproteomics among Arabidopsis ethylene response mutants is able to provide more valuable information about the molecular mechanisms underlying ethylene and gravity signaling pathways. (This work is supported by grants: RPC07/08.SC16, 661408, 661207, N HKUST627/06, DAG04/05.SC08, HKUST6105/01M, and HKUST6413/06M)

Significant Artifact Reduction at 1.5T and 3T MRI by the Use of a Cochlear Implant with Removable Magnet: An Experimental Human Cadaver Study

PubMed Central

Wagner, Franca; Wimmer, Wilhelm; Leidolt, Lars; Vischer, Mattheus; Weder, Stefan; Wiest, Roland; Mantokoudis, Georgios; Caversaccio, Marco D.

2015-01-01

Objective Cochlear implants (CIs) are standard treatment for postlingually deafened individuals and prelingually deafened children. This human cadaver study evaluated diagnostic usefulness, image quality and artifacts in 1.5T and 3T magnetic resonance (MR) brain scans after CI with a removable magnet. Methods Three criteria (diagnostic usefulness, image quality, artifacts) were assessed at 1.5T and 3T in five cadaver heads with CI. The brain magnetic resonance scans were performed with and without the magnet in situ. The criteria were analyzed by two blinded neuroradiologists, with focus on image distortion and limitation of the diagnostic value of the acquired MR images. Results MR images with the magnet in situ were all compromised by artifacts caused by the CI. After removal of the magnet, MR scans showed an unequivocal artifact reduction with significant improvement of the image quality and diagnostic usefulness, both at 1.5T and 3T. Visibility of the brain stem, cerebellopontine angle, and parieto-occipital lobe ipsilateral to the CI increased significantly after magnet removal. Conclusions The results indicate the possible advantages for 1.5T and 3T MR scanning of the brain in CI carriers with removable magnets. Our findings support use of CIs with removable magnets, especially in patients with chronic intracranial pathologies. PMID:26200775

Significant Artifact Reduction at 1.5T and 3T MRI by the Use of a Cochlear Implant with Removable Magnet: An Experimental Human Cadaver Study.

PubMed

Wagner, Franca; Wimmer, Wilhelm; Leidolt, Lars; Vischer, Mattheus; Weder, Stefan; Wiest, Roland; Mantokoudis, Georgios; Caversaccio, Marco D

2015-01-01

Cochlear implants (CIs) are standard treatment for postlingually deafened individuals and prelingually deafened children. This human cadaver study evaluated diagnostic usefulness, image quality and artifacts in 1.5T and 3T magnetic resonance (MR) brain scans after CI with a removable magnet. Three criteria (diagnostic usefulness, image quality, artifacts) were assessed at 1.5T and 3T in five cadaver heads with CI. The brain magnetic resonance scans were performed with and without the magnet in situ. The criteria were analyzed by two blinded neuroradiologists, with focus on image distortion and limitation of the diagnostic value of the acquired MR images. MR images with the magnet in situ were all compromised by artifacts caused by the CI. After removal of the magnet, MR scans showed an unequivocal artifact reduction with significant improvement of the image quality and diagnostic usefulness, both at 1.5T and 3T. Visibility of the brain stem, cerebellopontine angle, and parieto-occipital lobe ipsilateral to the CI increased significantly after magnet removal. The results indicate the possible advantages for 1.5T and 3T MR scanning of the brain in CI carriers with removable magnets. Our findings support use of CIs with removable magnets, especially in patients with chronic intracranial pathologies.

Diphosphine-Protected Au 22 Nanoclusters on Oxide Supports Are Active for Gas-Phase Catalysis without Ligand Removal

DOE PAGES

Wu, Zili; Hu, Guoxiang; Jiang, De-en; ...

2016-09-29

Investigation of monodispersed and atomically-precise Au nanoclusters provides a route to understand the roles of coordination, size, and ligand effects in Au catalysis. We have explored the catalytic behavior of a newly-synthesized Au 22(L 8) 6 nanocluster (L = 1,8-bis(diphenylphosphino) octane) with in situ uncoordinated Au sites supported on TiO 2, CeO 2 and Al 2O 3. Stability of the supported Au 22 nanoclusters was probed structurally by EXAFS and HAADF-STEM, and their adsorption and reactivity for CO oxidation were investigated by IR absorption spectroscopy and temperature programed flow reaction. Low temperature CO oxidation activity was observed for the supportedmore » pristine Au 22(L 8) 6 nanoclusters without ligand removal. Isotopically labeled O 2 was used to demonstrate that the reaction pathway occurs through a redox mechanism, consistent with the observed support-dependent activity trend: CeO 2 > TiO 2 > Al 2O 3. Substantiated by density functional theory (DFT) calculations, we conclude that the uncoordinated Au sites in the intact Au 22(L 8) 6 nanoclusters are capable of adsorbing CO, activating O2 and promoting CO oxidation reaction. Thanks to the presence of the in situ coordination unsaturated Au atoms, this work is the first clear demonstration of a ligand-protected Au nanocluster that are active for gas phase catalysis without the need of ligand removal.« less

mTOR plays critical roles in pancreatic cancer stem cells through specific and stemness-related functions

NASA Astrophysics Data System (ADS)

Matsubara, Shyuichiro; Ding, Qiang; Miyazaki, Yumi; Kuwahata, Taisaku; Tsukasa, Koichiro; Takao, Sonshin

2013-11-01

Pancreatic cancer is characterized by near-universal mutations in KRAS. The mammalian target of rapamycin (mTOR), which functions downstream of RAS, has divergent effects on stem cells. In the present study, we investigated the significance of the mTOR pathway in maintaining the properties of pancreatic cancer stem cells. The mTOR inhibitor, rapamycin, reduced the viability of CD133+ pancreatic cancer cells and sphere formation which is an index of self-renewal of stem-like cells, indicating that the mTOR pathway functions to maintain cancer stem-like cells. Further, rapamycin had different effects on CD133+ cells compared to cyclopamine which is an inhibitor of the Hedgehog pathway. Thus, the mTOR pathway has a distinct role although both pathways maintain pancreatic cancer stem cells. Therefore, mTOR might be a promising target to eliminate pancreatic cancer stem cells.

Arctigenin protects against ultraviolet-A-induced damage to stemness through inhibition of the NF-κB/MAPK pathway.

PubMed

Park, See-Hyoung; Cho, Jae Youl; Oh, Sae Woong; Kang, Mingyeong; Lee, Seung Eun; Yoo, Ju Ah; Jung, Kwangseon; Lee, Jienny; Lee, Sang Yeol; Lee, Jongsung

2018-02-25

The stemness of stem cells is negatively affected by ultraviolet A (UVA) irradiation. This study was performed to examine the effects of arctigenin on UVA-irradiation-induced damage to the stemness of human mesenchymal stem cells (hMSCs) derived from adipose tissue. The mechanisms of action of arctigenin were also investigated. A BrdU-incorporation assay demonstrated that arctigenin attenuated the UVA-induced reduction of the cellular proliferative potential. Arctigenin also increased the UVA-induced reduction in stemness of hMSCs by upregulating stemness-related genes such as SOX2, OCT4, and NANOG. In addition, the UVA-induced reduction in the mRNA expression level of hypoxia-inducible factor (HIF)-1α was significantly recovered by arctigenin. The antagonizing effect of arctigenin on UVA irradiation was mediated by reduced PGE 2 production through the inhibition of MAPKs (p42/44 MAPK, p38 MAPK, and JNK) and NF-κB. Overall, these findings suggest that arctigenin can ameliorate the reduced stemness of hMSCs induced by UVA irradiation. The effects of arctigenin are mediated by PGE 2 -cAMP signaling-dependent upregulation of HIF-1α. Therefore, arctigenin could be used as an antagonist to attenuate the effects of UVA irradiation. Copyright © 2018 Elsevier B.V. All rights reserved.

Stem cell mobilization with cyclophosphamide overcomes the suppressive effect of lenalidomide therapy on stem cell collection in multiple myeloma.

PubMed

Mark, Tomer; Stern, Jessica; Furst, Jessica R; Jayabalan, David; Zafar, Faiza; LaRow, April; Pearse, Roger N; Harpel, John; Shore, Tsiporah; Schuster, Michael W; Leonard, John P; Christos, Paul J; Coleman, Morton; Niesvizky, Ruben

2008-07-01

A total of 28 treatment-naïve patients with stage II or III multiple myeloma (MM) were treated with the combination of clarithromycin, lenalidomide, and dexamethasone (BiRD). Stem cells were collected following granulocyte-colony stimulating factor (G-CSF) or cyclophosphamide (Cy) plus G-CSF mobilization at maximum response. Sufficient stem cells for 2 autologous stem cell transplants were collected from all patients mobilized with Cy plus G-CSF, versus 33% mobilized with G-CSF alone (P < .0001). The duration of prior lenalidomide therapy did not correlate with success of stem cell harvests (P = .91). In conclusion, Cy can be added to G-CSF for stem cell mobilization to successfully overcome the suppressive effect of prior treatment with lenalidomide.

Stem Cell Mobilization with Cyclophosphamide Overcomes the Suppressive Effect of Lenalidomide Therapy on Stem Cell Collection in Multiple Myeloma

PubMed Central

Mark, Tomer; Stern, Jessica; Furst, Jessica R.; Jayabalan, David; Zafar, Faiza; LaRow, April; Pearse, Roger N.; Harpel, John; Shore, Tsiporah; Schuster, Michael W.; Leonard, John P.; Christos, Paul J.; Coleman, Morton; Niesvizky, Ruben

2013-01-01

A total of 28 treatment-naïve patients with stage II or III multiple myeloma (MM) were treated with the combination of clarithromycin, lenalidomide, and dexamethasone (BiRD). Stem cells were collected following granulocyte- colony stimulating factor (G-CSF) or cyclophosphamide (Cy) plus G-CSF mobilization at maximum response. Sufficient stem cells for 2 autologous stem cell transplants were collected from all patients mobilized with Cy plus G-CSF, versus 33% mobilized with G-CSF alone (P<.0001). The duration of prior lenalidomide therapy did not correlate with success of stem cell harvests (P = .91). In conclusion, Cy can be added to G-CSF for stem cell mobilization to successfully overcome the suppressive effect of prior treatment with lenalidomide. PMID:18541199

Tanshinone IIA inhibits cervix carcinoma stem cells migration and invasion via inhibiting YAP transcriptional activity.

PubMed

Qin, Jinghao; Shi, Hongbing; Xu, Yanjie; Zhao, Fang; Wang, Qing

2018-06-14

This study aims to explore the effects and related mechanisms of Tanshinone IIA in cervix carcinoma (CC) stemness-like cells migration, invasion, stemness and chemotherapeutical sensitivity. Here, we found that Tanshinone IIA suppressed CC stemness-like cells migration and invasion in a concentration- and time-dependent manner. And consistent results were obtained in CC cells stemness characterized as the decrease of CC stemness markers expression and cells spheroid formation ability. Mechanistically, we found that Tanshinone IIA suppressed RNA binding protein HuR translocation from nuclear to cytoplasm, and thus reduced YAP mRNAs stability and transcriptional activity. Importantly, overexpression YAP-5SA rescued the inhibition of Tanshinone IIA on CC cells stemness. Furthermore, Tanshinone IIA enhanced adriamycin sensitivity in CC stemness-like cells, this effect was attenuated by YAP-5SA overexpression too. Therefore, Tanshinone IIA could suppress CC stemness-like cells migration and invasion by inhibiting YAP transcriptional activity. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

The Integration of Research, Teaching, and Learning: Preparation of the Future STEM Faculty

NASA Astrophysics Data System (ADS)

Jariwala, Manher

Graduate students at research universities shape the future of STEM undergraduate education in the United States. These future faculty flow into the STEM faculties of several thousand research universities, comprehensive universities, liberal arts colleges, and community and tribal colleges. The Center for the Integration of Research, Teaching, and Learning (CIRTL) uses graduate education as the leverage point to develop STEM faculty with the capability and commitment to implement and improve effective teaching and learning practices. CIRTL has developed, implemented, and evaluated successful strategies based on three core ideas: teaching-as-research, learning communities, and learning-through-diversity. A decade of research demonstrates that STEM future faculty participating in CIRTL learning communities understand, use, and advance high-impact teaching practices. Today the CIRTL Network includes 43 research universities. Ultimately, CIRTL seeks a national STEM faculty who enable all students to learn effectively and achieve STEM literacy, whose teaching enhances recruitment into STEM careers, and whose leadership ensures continued advancement of STEM education.

IL-17B activated mesenchymal stem cells enhance proliferation and migration of gastric cancer cells.

PubMed

Bie, Qingli; Zhang, Bin; Sun, Caixia; Ji, Xiaoyun; Barnie, Prince Amoah; Qi, Chen; Peng, Jingjing; Zhang, Danyi; Zheng, Dong; Su, Zhaoliang; Wang, Shengjun; Xu, Huaxi

2017-03-21

Mesenchymal stem cells are important cells in tumor microenvironment. We have previously demonstrated that IL-17B/IL-17RB signal promoted progression of gastric cancer. In this study, we further explored the effect of IL-17B on mesenchymal stem cells in tumor microenvironment and its impact on the tumor progression. The results showed that IL-17B induced the expression of stemness-related genes Nanog, Sox2, and Oct4 in mesenchymal stem cells and enhanced its tumor-promoting effect. The supernatant from cultured mesenchymal stem cells after treating with exogenous rIL-17B promoted the proliferation and migration of MGC-803, therefor suggesting that rIL-17B might promote mesenchymal stem cells to produce soluble factors. In addition, rIL-17B also activated the NF-κΒ, STAT3, β-catenin pathway in mesenchymal stem cells. Our data revealed a new mechanism that IL-17B enhanced the progression of gastric cancer by activating mesenchymal stem cells.

Stem Cell Therapy for Healing Wounded Skin and Soft Tissues

DTIC Science & Technology

2012-07-01

changes of ASC surface markers due to repetitive in vitro sub-culturing. ASCs were harvested, washed in PBS to remove cell culture medium, and resuspended...Our in vitro and in vivo studies suggest that ASC and BM-MSC are not identical, though they have similar surface markers . We found that topically...ofpolybrene. Transduced cells were selected by treating 10 J.!g/rnl ofblasticidin. GFP expressing cells were further selected by flow cytometry using

Mesothelioma: Identification of the Key Molecular Events Triggered by BAP1

DTIC Science & Technology

2016-04-01

with 5ml of phosphate-buffered saline. The peritoneal cells obtained were pelleted and supernatant was removed for later cytokine analysis. Cells were...Interestingly, BAP1 has been recently shown to regulate the myeloid stem cell compartment via complex alterations of the transcriptional profile, possibly via...regulation of IL-6 activation by asbestos in lung epithelial cells : role of reactive oxygen species. J Immunol 1997; 159: 3921–3928. 43 Occupational

Large woody debris volumes and accumulation rates in cleaned streams in redwood forest in southern Humboldt County, California

Treesearch

John Wooster; Sue Hilton

2004-01-01

Large woody debris (LWD) was inventoried in 1999 in five streams where LWD was removed in the early 1980s, and no LWD has been artificially introduced since. All study sites are second order channels near the confluence of the South Fork and main-stem Eel River, California. Watershed contributing areas range from 4.7 to 17.4 km², and mean active channel widths...

Vital Pulp Therapy—Current Progress of Dental Pulp Regeneration and Revascularization

PubMed Central

Zhang, Weibo; Yelick, Pamela C.

2010-01-01

Pulp vitality is extremely important for the tooth viability, since it provides nutrition and acts as biosensor to detect pathogenic stimuli. In the dental clinic, most dental pulp infections are irreversible due to its anatomical position and organization. It is difficult for the body to eliminate the infection, which subsequently persists and worsens. The widely used strategy currently in the clinic is to partly or fully remove the contaminated pulp tissue, and fill and seal the void space with synthetic material. Over time, the pulpless tooth, now lacking proper blood supply and nervous system, becomes more vulnerable to injury. Recently, potential for successful pulp regeneration and revascularization therapies is increasing due to accumulated knowledge of stem cells, especially dental pulp stem cells. This paper will review current progress and feasible strategies for dental pulp regeneration and revascularization. PMID:20454445

Selenium in the upper Blackfoot River watershed, southeastern Idaho, 2001-12

USGS Publications Warehouse

Mebane, Christopher A.; Mladenka, Greg; Van Every, Lynn; Williams, Marshall L.; Hardy, Mark A.; Garbarino, John R.

2014-11-05

For the annual spring synoptic samples collected by the IDEQ along the main stem Blackfoot River and major tributaries, selenium concentrations ranged from less than 2 to 870 μg/L in 176 samples. In most years, the synoptic sampling showed that the majority of the selenium loads passing the USGS streamgage at the outlet of the watershed could be attributed to a single tributary, East Mill Creek, which enters the Blackfoot River through Spring Creek. Selenium loads decreased by about half from East Mill Creek before reaching the Blackfoot River, suggesting that much selenium is at least temporarily removed from the water column by uptake by aquatic vegetation or by losses to sediment. Similar decreases in selenium loads occurred through the main stem Blackfoot River before reaching the outlet in low flow years, but not in high flow years.

High-pressure paint gun injury to the orbit and ocular adnexa.

PubMed

Yip, C C; Tan, D T; Balakrishnan, V; Choo, C T

1998-01-01

High-pressure injection injury to the orbit and adnexa is a rare but potentially blinding type of trauma. Few cases of such injury have been reported in the literature. A 27-year-old Indian man accidentally injected paint material from a high-pressure nozzle gun into his left eye. Radiological investigation revealed the presence of paint material in the orbital tissues and the ethmoidal sinuses. The patient underwent two orbital surgeries to remove the paint material. He later developed signs suggestive of limbal stem cell failure and was treated with limbal stem cell autografting. He also has ophthalmoplegia with a compensatory anomalous head posture that was managed conservatively. We report the clinical course and outcome of this unfortunate patient to highlight the complexity of such an injury and the need for a multidisciplinary approach in its management.

Mesenchymal Stem Cells From Bone Marrow, Adipose Tissue, and Lung Tissue Differentially Mitigate Lung and Distal Organ Damage in Experimental Acute Respiratory Distress Syndrome.

PubMed

Silva, Johnatas D; Lopes-Pacheco, Miquéias; Paz, Ana H R; Cruz, Fernanda F; Melo, Elga B; de Oliveira, Milena V; Xisto, Débora G; Capelozzi, Vera L; Morales, Marcelo M; Pelosi, Paolo; Cirne-Lima, Elizabeth; Rocco, Patricia R M

2018-02-01

Mesenchymal stem cells-based therapies have shown promising effects in experimental acute respiratory distress syndrome. Different mesenchymal stem cells sources may result in diverse effects in respiratory diseases; however, there is no information regarding the best source of mesenchymal stem cells to treat pulmonary acute respiratory distress syndrome. We tested the hypothesis that mesenchymal stem cells derived from bone marrow, adipose tissue, and lung tissue would lead to different beneficial effects on lung and distal organ damage in experimental pulmonary acute respiratory distress syndrome. Animal study and primary cell culture. Laboratory investigation. Seventy-five Wistar rats. Wistar rats received saline (control) or Escherichia coli lipopolysaccharide (acute respiratory distress syndrome) intratracheally. On day 2, acute respiratory distress syndrome animals were further randomized to receive saline or bone marrow, adipose tissue, or lung tissue mesenchymal stem cells (1 × 10 cells) IV. Lung mechanics, histology, and protein levels of inflammatory mediators and growth factors were analyzed 5 days after mesenchymal stem cells administration. RAW 264.7 cells (a macrophage cell line) were incubated with lipopolysaccharide followed by coculture or not with bone marrow, adipose tissue, and lung tissue mesenchymal stem cells (10 cells/mL medium). Regardless of mesenchymal stem cells source, cells administration improved lung function and reduced alveolar collapse, tissue cellularity, collagen, and elastic fiber content in lung tissue, as well as decreased apoptotic cell counts in liver. Bone marrow and adipose tissue mesenchymal stem cells administration also reduced levels of tumor necrosis factor-α, interleukin-1β, keratinocyte-derived chemokine, transforming growth factor-β, and vascular endothelial growth factor, as well as apoptotic cell counts in lung and kidney, while increasing expression of keratinocyte growth factor in lung tissue. Additionally, mesenchymal stem cells differently modulated the secretion of biomarkers by macrophages depending on their source. Mesenchymal stem cells from different sources led to variable responses in lungs and distal organs. Bone marrow and adipose tissue mesenchymal stem cells yielded greater beneficial effects than lung tissue mesenchymal stem cells. These findings may be regarded as promising in clinical trials.

STEMulating Interest: A Meta-Analysis of the Effects of Out-of-School Time on Student STEM Interest

ERIC Educational Resources Information Center

Young, Jamaal; Ortiz, Nickolaus; Young, Jemimah

2017-01-01

This study is a meta-analysis of the effects of out-of-school time (after school, summer camps, enrichment programs, etc.) on the student interest in STEM. This study was guided by the following research questions: (1) How effective is OST as a means to foster student interest in STEM? (2) How does the effectiveness of OST differ by program and…

Inhibition of Aurora-A kinase induces cell cycle arrest in epithelial ovarian cancer stem cells by affecting NFκB pathway

PubMed Central

Alvero, Ayesha B; Visintin, Irene

2011-01-01

Recurrent ovarian cancer is resistant to conventional chemotherapy. A sub-population of ovarian cancer cells, the epithelial ovarian cancer stem cells (EOC stem cells) have stemness properties, constitutive NFκB activity, and represent the chemoresistant population. Currently, there is no effective treatment that targets these cells. Aurora-A kinase (Aurora-A) is associated with tumor initiation and progression and is overexpressed in numerous malignancies. The aim of this study is to determine the effect of Aurora-A inhibition in EOC stem cells. EOC stem cells were treated with the Aurora-A inhibitor, MK-5108. Cell growth was monitored by Incucyte real-time imaging system, cell viability was measured using the Celltiter 96 assay and cytokine levels were quantified using xMAP technology. The intracellular changes associated with MK-5108 treatment are: (1) polyploidy and cell cycle arrest; (2) inhibition of NFκB activity; (3) decreased cytokine production; and (4) nuclear accumulation of IκBα. Thus, inhibition of Aurora-A decreases cell proliferation in the EOC stem cells by inducing cell cycle arrest and affecting the NFκB pathway. As EOC stem cells represent a source of recurrence and chemoresistance, these results suggest that Aurora-A inhibition may effectively target the cancer stem cell population in ovarian cancer. PMID:21623171

JMJD3 suppresses stem cell-like characteristics in breast cancer cells by downregulation of Oct4 independently of its demethylase activity.

PubMed

Xun, Jing; Wang, Dekun; Shen, Long; Gong, Junbo; Gao, Ruifang; Du, Lingfang; Chang, Antao; Song, Xiangrong; Xiang, Rong; Tan, Xiaoyue

2017-03-28

Epigenetic regulator JMJD3 plays an important role in both tumor progression and somatic cell reprogramming. Here, we explored the effect of JMJD3 on the stem cell-like characteristics of breast cancer and its underlying mechanism involving stemness-related transcription factor Oct4. Our data revealed that, in breast cancer cells lines and an orthotopic xenograph mouse model of breast cancer, ectopic overexpression of JMJD3 suppressed stem cell-like characteristics of breast cancer cells, whereas knockdown of JMJD3 promoted these characteristics. Oct4 mediated the suppressive effects of JMJD3 on the stemness of breast cancer cells. The inhibitory effect of JMJD3 on Oct4 was independent of demethylase activity, but mediated via degradation of PHF20. Furthermore, we applied an agonist of the vitamin D receptor, paricalcitol, and found that it induced JMJD3 in breast cancer cells. Our data showed that administration of paricalcitol suppressed stem cell-like characteristics and Oct4 expression. Taken together, JMJD3 inhibits the stem cell-like characteristics in breast cancer by suppression of stemness factor Oct4 in a PHF20-dependent manner. Administration of paricalcitol leads to upregulation of JMJD3 that suppresses Oct4 expression and the stem cell-like characteristics in breast cancer.

Changes in human bone marrow fat content associated with changes in hematopoietic stem cell numbers and cytokine levels with aging.

PubMed

Tuljapurkar, Sonal R; McGuire, Timothy R; Brusnahan, Susan K; Jackson, John D; Garvin, Kevin L; Kessinger, Margaret A; Lane, Judy T; O' Kane, Barbara J; Sharp, John G

2011-11-01

Hematological deficiencies increase with aging, including anemias, reduced responses to hematopoietic stress and myelodysplasias. This investigation tested the hypothesis that increased bone marrow (BM) fat content in humans with age was associated with decreased numbers of side population (SP) hematopoietic stem cells, and this decrease correlated with changes in cytokine levels. BM was obtained from the femoral head and trochanteric region of the femur removed at surgery for total hip replacement (N = 100 subjects). In addition, BM from cadavers (N = 36), with no evidence of hip disease, was evaluated for fat content. Whole trabecular marrow samples were ground in a sterile mortar and pestle, and cellularity and lipid content determined. Marrow cells were stained with Hoechst dye and SP profiles were acquired. Plasma levels of insulin-like growth factor (IGF)-1, stromal-derived factor (SDF)-1 and interleukin (IL)-6 were measured using ELISA. Fat content in the BM of human subjects and cadavers increased with age. The numbers of SP stem cells in BM as well as plasma IGF-1 and SDF-1 levels decreased in correlation with increased BM fat. IL-6 had no relationship to changes in marrow fat. These data suggest that increased BM fat may be associated with a decreased number of SP stem cells and IGF-1 and SDF-1 levels with aging. These data further raise a more general question as to the role of adipose cells in the regulation of tissue stem cells. © 2011 The Authors. Journal of Anatomy © 2011 Anatomical Society of Great Britain and Ireland.

Regeneration of Corneal Epithelium With Dental Pulp Stem Cells Using a Contact Lens Delivery System.

PubMed

Kushnerev, Evgeny; Shawcross, Susan G; Sothirachagan, Shankari; Carley, Fiona; Brahma, Arun; Yates, Julian M; Hillarby, M Chantal

2016-10-01

The corneal epithelium is sloughed off surface of the eye by the action of blinking and is continually replaced by division and maturation of the limbal stem cells (LSCs). In the case of injury or disease, LSCs can be lost or damaged to a point at which the corneal epithelial layer is no longer maintained. leading to LSC deficiencies (LSCDs). When this occurs, the opaque conjunctiva overgrows the anterior surface of the eye, leading to vision impairment or loss. Dental pulp stem cells (DPSCs) are promising candidates as autologous LSC substitutes. In this study, contact lenses (CLs) are used as a novel medical device to deliver DPSCs onto corneal surface to enhance corneal epithelium regeneration. Dental pulp stem cells labeled with green fluorescent Qtracker 525 were seeded onto the pretreated CLs, allowed to adhere, then delivered to debrided human corneas. Expression of KRT3, 12, 13, and 19 was investigated by immunostaining, then standard and confocal microscopy. Dental pulp stem cells were successfully isolated, labeled, and delivered to the corneal surface using CLs. Following removal of CLs, confocal microscopy showed that the DPSCs had migrated onto the cornea. Coexpression of KRT12 and green fluorescent Qtracker 525 confirmed that the DPSCs had transdifferentiated into corneal epithelial progenitors. Delimitation of KRT 19 and green fluorescence provides evidence that Qtracker 525-labeled DPSCs establish a barrier to the invasion of the cornea by conjunctiva. In this study we show that DPSCs, delivered using CLs, can be used to enhance repair and regeneration of the human corneal epithelium.

Biological approaches to tackle heavy metal pollution: A survey of literature.

PubMed

Jacob, Jaya Mary; Karthik, Chinnannan; Saratale, Rijuta Ganesh; Kumar, Smita S; Prabakar, Desika; Kadirvelu, K; Pugazhendhi, Arivalagan

2018-07-01

Pollution by heavy metals has been identified as a global threat since the inception of industrial revolution. Heavy metal contamination induces serious health and environmental hazards due to its toxic nature. Remediation of heavy metals by conventional methods is uneconomical and generates a large quantity of secondary wastes. On the other hand, biological agents such as plants, microorganisms etc. offer easy and eco-friendly ways for metal removal; hence, considered as efficient and alternative tools for metal removal. Bioremediation involves adsorption, reduction or removal of contaminants from the environment through biological resources (both microorganisms and plants). The heavy metal remediation properties of microorganisms stem from their self defense mechanisms such as enzyme secretion, cellular morphological changes etc. These defence mechanisms comprise the active involvement of microbial enzymes such as oxidoreductases, oxygenases etc, which influence the rates of bioremediation. Further, immobilization techniques are improving the practice at industrial scales. This article summarizes the various strategies inherent in the biological sorption and remediation of heavy metals. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biosorption of metal ions from aqueous solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jiaping; Yiacoumi, Sotira

1997-01-01

Copper biosorption from aqueous solutions by calcium alginate is reported in this paper. The experimental section includes potentiometric titrations of biosorbents, batch equilibrium and kinetic studies of copper biosorption, as well as fixed-bed biosorption experiments. The potentiometric titration results show that the surface charge increases with decreasing pH. The biosorption of copper strongly depends on solution pH; the metal ion binding increases from 0 to 90 percent in pH ranging from 1.5 to 5.0. In addition, a decrease in ionic strength results in an increase of copper ion removal. Kinetic studies indicate that mass transfer plays an important role inmore » the biosorption rate. Furthermore, a fixed-bed biosorption experiment shows that calcium alginate has a significant capacity for copper ion removal. The two-pK Basic Stem model successfully represents the surface charge and equilibrium biosorption experimental data. The calculation results demonstrate that the copper removal may result from the binding of free copper and its hydroxide with surface functional groups of the biosorbents.« less

Glycols modulate terminator stem stability and ligand-dependency of a glycine riboswitch.

PubMed

Hamachi, Kokoro; Hayashi, Hikari; Shimamura, Miyuki; Yamaji, Yuiha; Kaneko, Ai; Fujisawa, Aruma; Umehara, Takuya; Tamura, Koji

2013-08-01

The Bacillus subtilis glycine riboswitch comprises tandem glycine-binding aptamers and a putative terminator stem followed by the gcvT operon. Gene expression is regulated via the sensing of glycine. However, we found that the riboswitch behaves in a "glycine-independent" manner in the presence of polyethylene glycol (PEG) and ethylene glycol. The effect is related to the formation of a terminator stem within the expression platform under such conditions. The results revealed that increasing PEG stabilized the structure of the terminator stem. By contrast, the addition of ethylene glycol destabilized the terminator stem. PEG and ethylene glycol have opposite effects on transcription as well as on stable terminator stem formation. The glycine-independency of the riboswitch and the effects of such glycols might shed light on the evolution of riboswitches. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Recent Progress in Stem Cell Modification for Cardiac Regeneration

PubMed Central

Voronina, Natalia; Steinhoff, Gustav

2018-01-01

During the past decades, stem cell-based therapy has acquired a promising role in regenerative medicine. The application of novel cell therapeutics for the treatment of cardiovascular diseases could potentially achieve the ambitious aim of effective cardiac regeneration. Despite the highly positive results from preclinical studies, data from phase I/II clinical trials are inconsistent and the improvement of cardiac remodeling and heart performance was found to be quite limited. The major issues which cardiac stem cell therapy is facing include inefficient cell delivery to the site of injury, accompanied by low cell retention and weak effectiveness of remaining stem cells in tissue regeneration. According to preclinical and clinical studies, various stem cells (adult stem cells, embryonic stem cells, and induced pluripotent stem cells) represent the most promising cell types so far. Beside the selection of the appropriate cell type, researchers have developed several strategies to produce “second-generation” stem cell products with improved regenerative capacity. Genetic and nongenetic modifications, chemical and physical preconditioning, and the application of biomaterials were found to significantly enhance the regenerative capacity of transplanted stem cells. In this review, we will give an overview of the recent developments in stem cell engineering with the goal to facilitate stem cell delivery and to promote their cardiac regenerative activity. PMID:29535769

A systematic review on the role of environmental toxicants in stem cells aging.

PubMed

Hodjat, Mahshid; Rezvanfar, Mohammad Amin; Abdollahi, Mohammad

2015-12-01

Stem cells are an important target for environmental toxicants. As they are the main source for replenishing of organs in the body, any changes in their normal function could affect the regenerative potential of organs, leading to the appearance of age-related disease and acceleration of the aging process. Environmental toxicants could exert their adverse effect on stem cell function via multiple cellular and molecular mechanisms, resulting in changes in the stem cell differentiation fate and cell transformation, and reduced self-renewal capacity, as well as induction of stress-induced cellular senescence. The present review focuses on the effect of environmental toxicants on stem cell function associated with the aging process. We categorized environmental toxicants according to their preferred molecular mechanism of action on stem cells, including changes in genomic, epigenomic, and proteomic levels and enhancing oxidative stress. Pesticides, tobacco smoke, radiation and heavy metals are well-studied toxicants that cause stem cell dysfunction via induction of oxidative stress. Transgenerational epigenetic changes are the most important effects of a variety of toxicants on germ cells and embryos that are heritable and could affect health in the next several generations. A better understanding of the underlying mechanisms of toxicant-induced stem cell aging will help us to develop therapeutic intervention strategies against environmental aging. Meanwhile, more efforts are required to find the direct in vivo relationship between adverse effect of environmental toxicants and stem cell aging, leading to organismal aging. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antagonizing Effects of Aspartic Acid against Ultraviolet A-Induced Downregulation of the Stemness of Human Adipose Tissue-Derived Mesenchymal Stem Cells.

PubMed

Jung, Kwangseon; Cho, Jae Youl; Soh, Young-Jin; Lee, Jienny; Shin, Seoung Woo; Jang, Sunghee; Jung, Eunsun; Kim, Min Hee; Lee, Jongsung

2015-01-01

Ultraviolet A (UVA) irradiation is responsible for a variety of changes in cell biology. The purpose of this study was to investigate effects of aspartic acid on UVA irradiation-induced damages in the stemness properties of human adipose tissue-derived mesenchymal stem cells (hAMSCs). Furthermore, we elucidated the UVA-antagonizing mechanisms of aspartic acid. The results of this study showed that aspartic acid attenuated the UVA-induced reduction of the proliferative potential and stemness of hAMSCs, as evidenced by increased proliferative activity in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and upregulation of stemness-related genes OCT4, NANOG, and SOX2 in response to the aspartic acid treatment. UVA-induced reduction in the mRNA level of hypoxia-inducible factor (HIF)-1α was also significantly recovered by aspartic acid. In addition, the antagonizing effects of aspartic acid against the UVA effects were found to be mediated by reduced production of PGE2 through the inhibition of JNK and p42/44 MAPK. Taken together, these findings show that aspartic acid improves reduced stemness of hAMSCs induced by UVA and its effects are mediated by upregulation of HIF-1α via the inhibition of PGE2-cAMP signaling. In addition, aspartic acid may be used as an antagonizing agent to mitigate the effects of UVA.

The Effect Of Stem Degrees On The Performance And Retention Of Junior Officers In The U.S. Navy

DTIC Science & Technology

2016-03-01

REPORT TYPE AND DATES COVERED Master’s thesis 4 . TITLE AND SUBTITLE THE EFFECT OF STEM DEGREES ON THE PERFORMANCE AND RETENTION OF JUNIOR OFFICERS IN...has positive and significant effects on retention and on promotion to O- 4 , and a negative effect on Fitness Report performance. Further research can...inconclusive, this thesis’s findings show that a STEM degree has positive and significant effects on retention and on promotion to O- 4 , and a negative effect

Intrinsic and extrinsic mechanical properties related to the differentiation of mesenchymal stem cells.

PubMed

Lee, Jin-Ho; Park, Hun-Kuk; Kim, Kyung Sook

2016-05-06

Diverse intrinsic and extrinsic mechanical factors have a strong influence on the regulation of stem cell fate. In this work, we examined recent literature on the effects of mechanical environments on stem cells, especially on differentiation of mesenchymal stem cells (MSCs). We provide a brief review of intrinsic mechanical properties of single MSC and examined the correlation between the intrinsic mechanical property of MSC and the differentiation ability. The effects of extrinsic mechanical factors relevant to the differentiation of MSCs were considered separately. The effect of nanostructure and elasticity of the matrix on the differentiation of MSCs were summarized. Finally, we consider how the extrinsic mechanical properties transfer to MSCs and then how the effects on the intrinsic mechanical properties affect stem cell differentiation. Copyright © 2015 Elsevier Inc. All rights reserved.

Wnt Pathway Regulation of Embryonic Stem Cell Self-Renewal

PubMed Central

Merrill, Bradley J.

2012-01-01

Embryonic stem cells (ESCs) can generate all of the cell types found in the adult organism. Remarkably, they retain this ability even after many cell divisions in vitro, as long as the culture conditions prevent differentiation of the cells. Wnt signaling and β-catenin have been shown to cause strong effects on ESCs both in terms of stimulating the expansion of stem cells and stimulating differentiation toward lineage committed cell types. The varied effects of Wnt signaling in ESCs, alongside the sometimes unconventional mechanisms underlying the effects, have generated a fair amount of controversy and intrigue regarding the role of Wnt signaling in pluripotent stem cells. Insights into the mechanisms of Wnt function in stem cells can be gained by examination of the causes for seemingly opposing effects of Wnt signaling on self-renewal versus differentiation. PMID:22952393

Perfluorooctane sulfonate induces neuronal and oligodendrocytic differentiation in neural stem cells and alters the expression of PPARγ in vitro and in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan Ibrahim, Wan Norhamidah, E-mail: hamidah@science.upm.edu.my; Tofighi, Roshan, E-mail: Roshan.Tofighi@ki.se; Onishchenko, Natalia, E-mail: Natalia.Onishchenko@ki.se

2013-05-15

Perfluorinated compounds are ubiquitous chemicals of major concern for their potential adverse effects on the human population. We have used primary rat embryonic neural stem cells (NSCs) to study the effects of perfluorooctane sulfonate (PFOS) on the process of NSC spontaneous differentiation. Upon removal of basic fibroblast growth factor, NSCs were exposed to nanomolar concentrations of PFOS for 48 h, and then allowed to differentiate for additional 5 days. Exposure to 25 or 50 nM concentration resulted in a lower number of proliferating cells and a higher number of neurite-bearing TuJ1-positive cells, indicating an increase in neuronal differentiation. Exposure tomore » 50 nM also significantly increased the number of CNPase-positive cells, pointing to facilitation of oligodendrocytic differentiation. PPAR genes have been shown to be involved in PFOS toxicity. By q-PCR we detected an upregulation of PPARγ with no changes in PPARα or PPARδ genes. One of the downstream targets of PPARs, the mitochondrial uncoupling protein 2 (UCP2) was also upregulated. The number of TuJ1- and CNPase-positive cells increased after exposure to PPARγ agonist rosiglitazone (RGZ, 3 μM) and decreased after pre-incubation with the PPARγ antagonist GW9662 (5 μM). RGZ also upregulated the expression of PPARγ and UCP2 genes. Meanwhile GW9662 abolished the UCP2 upregulation and decreased Ca{sup 2+} activity induced by PFOS. Interestingly, a significantly higher expression of PPARγ and UCP3 genes was also detected in mouse neonatal brain after prenatal exposure to PFOS. These data suggest that PPARγ plays a role in the alteration of spontaneous differentiation of NSCs induced by nanomolar concentrations of PFOS. - Highlights: • PFOS decreases proliferation of neural stem cells (NSCs). • PFOS induces neuronal and oligodendrocytic differentiation in NSCs. • PFOS alters expression of PPARγ and UCP2 in vitro. • PFOS alters expression of PPARγ and UCP3 in vivo. • Block of PPARγ by the selective antagonist GW9662 abolishes the effects of PFOS.« less

Preservation of Differentiation and Clonogenic Potential of Human Hematopoietic Stem and Progenitor Cells during Lyophilization and Ambient Storage

PubMed Central

Buchanan, Sandhya S.; Pyatt, David W.; Carpenter, John F.

2010-01-01

Progenitor cell therapies show great promise, but their potential for clinical applications requires improved storage and transportation. Desiccated cells stored at ambient temperature would provide economic and practical advantages over approaches employing cell freezing and subzero temperature storage. The objectives of this study were to assess a method for loading the stabilizing sugar, trehalose, into hematopoietic stem and progenitor cells (HPC) and to evaluate the effects of subsequent freeze-drying and storage at ambient temperature on differentiation and clonogenic potential. HPC were isolated from human umbilical cord blood and loaded with trehalose using an endogenous cell surface receptor, termed P2Z. Solution containing trehalose-loaded HPC was placed into vials, which were transferred to a tray freeze-dryer and removed during each step of the freeze-drying process to assess differentiation and clonogenic potential. Control groups for these experiments were freshly isolated HPC. Control cells formed 1450±230 CFU-GM, 430±140 BFU-E, and 50±40 CFU-GEMM per 50 µL. Compared to the values for the control cells, there was no statistical difference observed for cells removed at the end of the freezing step or at the end of primary drying. There was a gradual decrease in the number of CFU-GM and BFU-E for cells removed at different temperatures during secondary drying; however, there were no significant differences in the number of CFU-GEMM. To determine storage stability of lyophilized HPC, cells were stored for 4 weeks at 25°C in the dark. Cells reconstituted immediately after lyophilization produced 580±90 CFU-GM (∼40%, relative to unprocessed controls p<0.0001), 170±70 BFU-E (∼40%, p<0.0001), and 41±22 CFU-GEMM (∼82%, p = 0.4171), and cells reconstituted after 28 days at room temperature produced 513±170 CFU-GM (∼35%, relative to unprocessed controls, p<0.0001), 112±68 BFU-E (∼26%, p<0.0001), and 36±17 CFU-GEMM (∼82%, p = 0.2164) These studies are the first to document high level retention of CFU-GEMM following lyophilization and storage for 4 weeks at 25°C. This type of flexible storage stability would potentially permit the ability to ship and store HPC without the need for refrigeration. PMID:20824143

Preservation of differentiation and clonogenic potential of human hematopoietic stem and progenitor cells during lyophilization and ambient storage.

PubMed

Buchanan, Sandhya S; Pyatt, David W; Carpenter, John F

2010-09-01

Progenitor cell therapies show great promise, but their potential for clinical applications requires improved storage and transportation. Desiccated cells stored at ambient temperature would provide economic and practical advantages over approaches employing cell freezing and subzero temperature storage. The objectives of this study were to assess a method for loading the stabilizing sugar, trehalose, into hematopoietic stem and progenitor cells (HPC) and to evaluate the effects of subsequent freeze-drying and storage at ambient temperature on differentiation and clonogenic potential. HPC were isolated from human umbilical cord blood and loaded with trehalose using an endogenous cell surface receptor, termed P2Z. Solution containing trehalose-loaded HPC was placed into vials, which were transferred to a tray freeze-dryer and removed during each step of the freeze-drying process to assess differentiation and clonogenic potential. Control groups for these experiments were freshly isolated HPC. Control cells formed 1450+/-230 CFU-GM, 430+/-140 BFU-E, and 50+/-40 CFU-GEMM per 50 microL. Compared to the values for the control cells, there was no statistical difference observed for cells removed at the end of the freezing step or at the end of primary drying. There was a gradual decrease in the number of CFU-GM and BFU-E for cells removed at different temperatures during secondary drying; however, there were no significant differences in the number of CFU-GEMM. To determine storage stability of lyophilized HPC, cells were stored for 4 weeks at 25 degrees C in the dark. Cells reconstituted immediately after lyophilization produced 580+/-90 CFU-GM ( approximately 40%, relative to unprocessed controls p<0.0001), 170+/-70 BFU-E (approximately 40%, p<0.0001), and 41+/-22 CFU-GEMM (approximately 82%, p = 0.4171), and cells reconstituted after 28 days at room temperature produced 513+/-170 CFU-GM (approximately 35%, relative to unprocessed controls, p<0.0001), 112+/-68 BFU-E (approximately 26%, p<0.0001), and 36+/-17 CFU-GEMM ( approximately 82%, p = 0.2164) These studies are the first to document high level retention of CFU-GEMM following lyophilization and storage for 4 weeks at 25 degrees C. This type of flexible storage stability would potentially permit the ability to ship and store HPC without the need for refrigeration.

Angiogenic Capacity of Periodontal Ligament Stem Cells Pretreated with Deferoxamine and/or Fibroblast Growth Factor-2

PubMed Central

Ratajczak, Jessica; Hilkens, Petra; Gervois, Pascal; Wolfs, Esther; Jacobs, Reinhilde; Lambrichts, Ivo; Bronckaers, Annelies

2016-01-01

Periodontal ligament stem cells (PDLSCs) represent a good source of multipotent cells for cell-based therapies in regenerative medicine. The success rate of these treatments is severely dependent on the establishment of adequate vasculature in order to provide oxygen and nutrients to the transplanted cells. Pharmacological preconditioning of stem cells has been proposed as a promising method to augment their therapeutic efficacy. In this study, the aim was to improve the intrinsic angiogenic properties of PDLSCs by in vitro pretreatment with deferoxamine (DFX; 100μM), fibroblast growth factor-2 (FGF-2; 10ng/mL) or both substances combined. An antibody array revealed the differential expression of several proteins, including vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). ELISA data confirmed a 1.5 to 1.8-fold increase in VEGF for all tested conditions. Moreover, 48 hours after the removal of DFX, VEGF levels remained elevated (1.8-fold) compared to control conditions. FGF-2 and combination treatment resulted in a 5.4 to 13.1-fold increase in PlGF secretion, whereas DFX treatment had no effect. Furthermore, both PDLSCs as pretreated PDLSCs induced endothelial migration. Despite the significant elevated VEGF levels of pretreated PDLSCs, the induced endothelial migration was not higher by pretreated PDLSCs. We find that the observed induced endothelial cell motility was not dependent on VEGF, since blocking the VEGFR1-3 with Axitinib (0.5nM) did not inhibit endothelial motility towards PDLSCs. Taken together, this study provides evidence that preconditioning with DFX and/or FGF-2 significantly improves the angiogenic secretome of PDLSCs, in particular VEGF and PlGF secretion. However, our data suggest that VEGF is not the only player when it comes to influencing endothelial behavior by the PDLSCs. PMID:27936076

Rapid tissue engineering of biomimetic human corneal limbal crypts with 3D niche architecture.

PubMed

Levis, Hannah J; Massie, Isobel; Dziasko, Marc A; Kaasi, Andreas; Daniels, Julie T

2013-11-01

Limbal epithelial stem cells are responsible for the maintenance of the human corneal epithelium and these cells reside in a specialised stem cell niche. They are located at the base of limbal crypts, in a physically protected microenvironment in close proximity to a variety of neighbouring niche cells. Design and recreation of elements of various stem cell niches have allowed researchers to simplify aspects of these complex microenvironments for further study in vitro. We have developed a method to rapidly and reproducibly create bioengineered limbal crypts (BLCs) in a collagen construct using a simple one-step method. Liquid is removed from collagen hydrogels using hydrophilic porous absorbers (HPAs) that have custom moulded micro-ridges on the base. The resulting topography on the surface of the thin collagen constructs resembles the dimensions of the stromal crypts of the human limbus. Human limbal epithelial cells seeded onto the surface of the constructs populate these BLCs and form numerous layers with a high proportion of the cells lining the crypts expressing putative stem cell marker, p63α. The HPAs are produced using a moulding process that is flexible and can be adapted depending on the requirements of the end user. Creation of defined topographical features using this process could be applicable to numerous tissue-engineering applications where varied 3-dimensional niche architectures are required. Copyright © 2013 Elsevier Ltd. All rights reserved.

Curved-stem Hip Resurfacing

PubMed Central

2008-01-01

Hip resurfacing is an attractive concept because it preserves rather than removes the femoral head and neck. Most early designs had high failure rates, but one unique design had a femoral stem. Because that particular device appeared to have better implant survival, this study assessed the clinical outcome and long-term survivorship of a hip resurfacing prosthesis. Four hundred forty-five patients (561 hips) were retrospectively reviewed after a minimum of 20 years’ followup or until death; 23 additional patients were lost to followup. Patients received a metal femoral prosthesis with a small curved stem. Three types of acetabular reconstructions were used: (1) cemented polyurethane; (2) metal-on-metal; and (3) polyethylene secured with cement or used as the liner of a two-piece porous-coated implant. Long-term results were favorable with the metal-on-metal combination only. The mean overall Harris hip score was 92 at 2 years of followup. None of the 121 patients (133 hips) who received metal-on-metal articulation experienced failure. The failure rate with polyurethane was 100%, and the failure rate with cemented polyethylene was 41%. Hip resurfacing with a curved-stem femoral component had a durable clinical outcome when a metal-on-metal articulation was used. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18338217

Development of Paper Products from Dried Sweetpotato Stems and Peanut Shells

NASA Technical Reports Server (NTRS)

McConnell, R.; Smith, R.; Jones, G.; Lu, J. Y.

1998-01-01

One of the goals of NASA's Advanced Life Support Program (ALS) for sustaining human life in space is to achieve a closed system in plant production and usage. That all inedible plant parts should be recycled or used in some way. A Tuskegee University team researching sweetpotato and peanut for ALS has developed paper products from dried sweet-potato stems and peanut shells. In this study, the sweet-potato stems and peanut shells were soaked separately in water for 48 hours. After 48 hours, researchers manually separated the pulp and the unusable parts. To form the paper, 160 g of pulp and water mixture was poured through a 15.1 cm (diameter) filtration funnel and the pulp was trapped on 15 cm (diameter) filter paper. The filter paper and pulp were dried in an air oven, and the filter paper was removed, An examination under a scanning electron microscope showed that the sweet-potato paper was composed of "fibers", whereas the peanut shell paper was composed of "blocks". Results of physical testing showed that the sweet-potato stem paper was stronger than the peanut shell paper. It is anticipated that there may be other uses of these products such as writing paper, bags and packaging material. Because of its biodegradability, it can be incorporated into the resource recycling system at the end of its use.

Effects of Transferring to STEM-Focused Charter and Magnet Schools on Student Achievement

ERIC Educational Resources Information Center

Judson, Eugene

2014-01-01

There have been strong calls to action in recent years to promote both school choice and the learning of science, technology, engineering, and mathematics (STEM). This has led to the burgeoning development of STEM-focused schools. Nine STEM-focused charter and 2 STEM-focused magnet schools that serve elementary-aged students were examined to…

Astronomy in Denver: Effects of a summer camp on girls’ preconceived notions of careers in STEM

NASA Astrophysics Data System (ADS)

Hoffman, Jennifer L.; Fetrow, Kirsten J.; Broder, Dale E.; Murphy, Shannon M.; Tinghitella, Robin; Hart, Quyen N.

2018-06-01

Despite gains in recent years, gender disparities persist in fields related to science, technology, engineering, and mathematics (STEM). Although young women can perform as well as their male peers in STEM courses and tests, they are less likely to pursue higher education and careers in STEM. Our study examined the effectiveness of a STEM-focused summer camp at increasing middle-school girls’ career aspirations in STEM and self-confidence with respect to scientific topics. The 15 participants were Denver-area girls ages 10 to 13 years old from groups underrepresented in STEM fields. During the weeklong DU SciTech camp, these girls built telescopes and computers, collected and classified insects, completed inquiry activities, and interacted with female STEM professionals from a variety of scientific fields and racial backgrounds. We hypothesized that camp attendance would expand girls’ perceptions of who does science, increase their awareness of and interest in STEM careers, and increase their scientific self-efficacy, or belief in their ability to succeed at STEM tasks. We found that DU SciTech improved the girls’ scientific self-efficacy and awareness of STEM careers, but it did not increase their (already high) interest in pursuing their own careers in STEM. We will present our results and discuss their implications for future summer camps and efforts to broaden STEM participation by young women from underrepresented groups.

Multi-effects of Resveratrol on stem cell characteristics: Effective dose, time, cell culture conditions and cell type-specific responses of stem cells to Resveratrol.

PubMed

Safaeinejad, Zahra; Kazeminasab, Fatemeh; Kiani-Esfahani, Abbas; Ghaedi, Kamran; Nasr-Esfahani, Mohammad Hossein

2018-06-18

Stem cells which defined by dual features of self-renewal and differentiation potential provide a unique source for repairing damaged tissues to treat a wide spectrum of diseases and injuries. Several recent studies suggest that Resveratrol (RSV), a natural polyphenol component, possesses the ability to improve either culture conditions of stem cells or their target differentiation in culture. This review covers the literature that deals with the effects of RSV and its underlying mechanisms on survival, self-renewal and lineage commitment of various stem cells. Concentration of RSV and duration of treatment with this component could exert differential effects on cellular differentiation processes and cell fate. Therefore, RSV could be accounted as an effective small molecule for a variety of cell therapies which should be implemented by a special care considering, effective concentration and duration of exposure. Copyright © 2018. Published by Elsevier Masson SAS.

Learning to teach effectively: Science, technology, engineering, and mathematics graduate teaching assistants' teaching self-efficacy

NASA Astrophysics Data System (ADS)

Dechenne, Sue Ellen

Graduate teaching assistants (GTAs) from science, technology, engineering, and mathematics (STEM) are important in the teaching of undergraduate students (Golde & Dore, 2001). However, they are often poorly prepared for teaching (Luft, Kurdziel, Roehrig, & Turner, 2004). This dissertation addresses teaching effectiveness in three related manuscripts: (1) A position paper that summarizes the current research on and develops a model of GTA teaching effectiveness. (2) An adaptation and validation of two instruments; GTA perception of teaching training and STEM GTA teaching self-efficacy. (3) A model test of factors that predict STEM GTA teaching self-efficacy. Together these three papers address key questions in the understanding of teaching effectiveness in STEM GTAs including: (a) What is our current knowledge of factors that affect the teaching effectiveness of GTAs? (b) Given that teaching self-efficacy is strongly linked to teaching performance, how can we measure STEM GTAs teaching self-efficacy? (c) Is there a better way to measure GTA teaching training than currently exists? (d) What factors predict STEM GTA teaching self-efficacy? An original model for GTA teaching effectiveness was developed from a thorough search of the GTA teaching literature. The two instruments---perception of training and teaching self-efficacy---were tested through self-report surveys using STEM GTAs from six different universities including Oregon State University (OSU). The data was analyzed using exploratory and confirmatory factor analysis. Using GTAs from the OSU colleges of science and engineering, the model of sources of STEM GTA teaching self-efficacy was tested by administering self-report surveys and analyzed by using OLS regression analysis. Language and cultural proficiency, departmental teaching climate, teaching self-efficacy, GTA training, and teaching experience affect GTA teaching effectiveness. GTA teaching self-efficacy is a second-order factor combined from self-efficacy for instructional strategies and a positive learning environment. It is correlated to GTA perception of teaching training and university GTA training. The K-12 teaching experience, GTA perception of teaching training, and facilitating factors in the departmental climate predict STEM GTA teaching self-efficacy. Hours of GTA training and supervision are fully mediated by perception of GTA training. Implications for research and training of STEM GTAs are discussed.

Semantic transparency in free stems: The effect of Orthography-Semantics Consistency on word recognition.

PubMed

Marelli, Marco; Amenta, Simona; Crepaldi, Davide

2015-01-01

A largely overlooked side effect in most studies of morphological priming is a consistent main effect of semantic transparency across priming conditions. That is, participants are faster at recognizing stems from transparent sets (e.g., farm) in comparison to stems from opaque sets (e.g., fruit), regardless of the preceding primes. This suggests that semantic transparency may also be consistently associated with some property of the stem word. We propose that this property might be traced back to the consistency, throughout the lexicon, between the orthographic form of a word and its meaning, here named Orthography-Semantics Consistency (OSC), and that an imbalance in OSC scores might explain the "stem transparency" effect. We exploited distributional semantic models to quantitatively characterize OSC, and tested its effect on visual word identification relying on large-scale data taken from the British Lexicon Project (BLP). Results indicated that (a) the "stem transparency" effect is solid and reliable, insofar as it holds in BLP lexical decision times (Experiment 1); (b) an imbalance in terms of OSC can account for it (Experiment 2); and (c) more generally, OSC explains variance in a large item sample from the BLP, proving to be an effective predictor in visual word access (Experiment 3).

Financial Barriers to STEM Study in College: Causal Effect Estimates of Need-Based Grants on the Pursuit and Completion of Courses and Degrees in STEM Fields

ERIC Educational Resources Information Center

Castleman, Benjamin L.; Long, Bridget Terry; Mabel, Zachary A.

2014-01-01

The fastest growing supply of jobs in the United States today is in Science, Technology, Engineering, and Mathematics (STEM) fields. Yet despite the availability of work in STEM, there is not a sufficient supply of workers to fill open positions. Amidst the growing demand for STEM workers, educational achievement and attainment in STEM fields in…

Advances in Bone Marrow Stem Cell Therapy for Retinal Dysfunction

PubMed Central

Park, Susanna S.; Moisseiev, Elad; Bauer, Gerhard; Anderson, Johnathon D.; Grant, Maria B.; Zam, Azhar; Zawadzki, Robert J.; Werner, John S.; Nolta, Jan A.

2016-01-01

The most common cause of untreatable vision loss is dysfunction of the retina. Conditions, such as age-related macular degeneration, diabetic retinopathy and glaucoma remain leading causes of untreatable blindness worldwide. Various stem cell approaches are being explored for treatment of retinal regeneration. The rationale for using bone marrow stem cells to treat retinal dysfunction is based on preclinical evidence showing that bone marrow stem cells can rescue degenerating and ischemic retina. These stem cells have primarily paracrine trophic effects although some cells can directly incorporate into damaged tissue. Since the paracrine trophic effects can have regenerative effects on multiple cells in the retina, the use of this cell therapy is not limited to a particular retinal condition. Autologous bone marrow-derived stem cells are being explored in early clinical trials as therapy for various retinal conditions. These bone marrow stem cells include mesenchymal stem cells, mononuclear cells and CD34+ cells. Autologous therapy requires no systemic immunosuppression or donor matching. Intravitreal delivery of CD34+ cells and mononuclear cells appears to be tolerated and is being explored since some of these cells can home into the damaged retina after intravitreal administration. The safety of intravitreal delivery of mesenchymal stem cells has not been well established. This review provides an update of the current evidence in support of the use of bone marrow stem cells as treatment for retinal dysfunction. The potential limitations and complications of using certain forms of bone marrow stem cells as therapy are discussed. Future directions of research include methods to optimize the therapeutic potential of these stem cells, non-cellular alternatives using extracellular vesicles, and in vivo high-resolution retinal imaging to detect cellular changes in the retina following cell therapy. PMID:27784628

Spaceflight Effects on the Hematopoietic Tissue of Ribbed Newts

NASA Astrophysics Data System (ADS)

Domaratskaya, E. I.; Almeida, E. A. C.; Butorina, N. N.; Nikonova, T. M.; Grigoryan, E. N.; Poplinskaya, V. A.

2008-06-01

The newts Pleurodeles waltl flown on Foton-M2 for 12 days were used for studying the effects of spaceflight on hematopoiesis in lower vertebrates. Prior to the flight, all the animals underwent to removal their lenses and tail tips for regeneration studies. No significant differences in blood cell contents were detected between flight and control animals. Morphological examination of hematopoietic areas of the liver in both groups also showed no significant differences. Experiments with BrdU incorporation revealed labeled cells in the hemopoietic area of the liver as well as in blood. The blood cell composition of newts flown on Foton-M3 was similar to that in intact (nonoperated) newts used in Bion-11 and Foton-M2 experiments. The lack of blood changes in newts during the current experiments distinguishes them from mammals flown in space (rats and mice), which developed significant changes in both blood cell counts, stem and committed cells in the blood-forming tissues.

Bromelain decreases neutrophil interactions with P-selectin, but not E-selectin, in vitro by proteolytic cleavage of P-selectin glycoprotein ligand-1.

PubMed

Banks, Jessica M; Herman, Christine T; Bailey, Ryan C

2013-01-01

Stem bromelain, a cysteine protease isolated from pineapples, is a natural anti-inflammatory treatment, yet its mechanism of action remains unclear. Curious as to whether bromelain might affect selectin-mediated leukocyte rolling, we studied the ability of bromelain-treated human neutrophils to tether to substrates presenting immobilized P-selectin or E-selectin under shear stress. Bromelain treatment attenuated P-selectin-mediated tethering but had no effect on neutrophil recruitment on E-selectin substrates. Flow cytometric analysis of human neutrophils, using two antibodies against distinct epitopes within the P-selectin glycoprotein ligand-1 (PSGL-1) active site, revealed that bromelain cleaves PSGL-1 to remove one of two sites required for P-selectin binding, while leaving the region required for E-selectin binding intact. These findings suggest one molecular mechanism by which bromelain may exert its anti-inflammatory effects is via selective cleavage of PSGL-1 to reduce P-selectin-mediated neutrophil recruitment.

Bromelain Decreases Neutrophil Interactions with P-Selectin, but Not E-Selectin, In Vitro by Proteolytic Cleavage of P-Selectin Glycoprotein Ligand-1

PubMed Central

Bailey, Ryan C.

2013-01-01

Stem bromelain, a cysteine protease isolated from pineapples, is a natural anti-inflammatory treatment, yet its mechanism of action remains unclear. Curious as to whether bromelain might affect selectin-mediated leukocyte rolling, we studied the ability of bromelain-treated human neutrophils to tether to substrates presenting immobilized P-selectin or E-selectin under shear stress. Bromelain treatment attenuated P-selectin-mediated tethering but had no effect on neutrophil recruitment on E-selectin substrates. Flow cytometric analysis of human neutrophils, using two antibodies against distinct epitopes within the P-selectin glycoprotein ligand-1 (PSGL-1) active site, revealed that bromelain cleaves PSGL-1 to remove one of two sites required for P-selectin binding, while leaving the region required for E-selectin binding intact. These findings suggest one molecular mechanism by which bromelain may exert its anti-inflammatory effects is via selective cleavage of PSGL-1 to reduce P-selectin-mediated neutrophil recruitment. PMID:24244398

Impact of electromagnetic fields on stem cells: common mechanisms at the crossroad between adult neurogenesis and osteogenesis

PubMed Central

Leone, Lucia; Podda, Maria Vittoria; Grassi, Claudio

2015-01-01

In the recent years adult neural and mesenchymal stem cells have been intensively investigated as effective resources for repair therapies. In vivo and in vitro studies have provided insights on the molecular mechanisms underlying the neurogenic and osteogenic processes in adulthood. This knowledge appears fundamental for the development of targeted strategies to manipulate stem cells. Here we review recent literature dealing with the effects of electromagnetic fields on stem cell biology that lends support to their use as a promising tool to positively influence the different steps of neurogenic and osteogenic processes. We will focus on recent studies revealing that extremely-low frequency electromagnetic fields enhance adult hippocampal neurogenesis by inducing epigenetic modifications on the regulatory sequences of genes responsible for neural stem cell proliferation and neuronal differentiation. In light of the emerging critical role played by chromatin modifications in maintaining the stemness as well as in regulating stem cell differentiation, we will also attempt to exploit epigenetic changes that can represent common targets for electromagnetic field effects on neurogenic and osteogenic processes. PMID:26124705

[Application of SPSS orthogonal design in tissue culture of Anoectochilus roxburghii].

PubMed

Zhang, Fusheng; Guo, Shunxing

2009-10-01

To study the effect of the different constitutions of plant hormone on the development of Anoectochilus roxburghii. A. roxburghii were harvested after having been cultured for 60 days. An orthogonal design was used to study the effect of NAA and 6-BA on the leaf number, eustipe number, lateral branch number of the stem tip and stem section, and the height of the stem tips. All of the data were processed by SPSS. It is reported for the first time that NAA could make different development of A. roxburghii at low concentration ( < 1 mg L(-1)) and high concentration ( > 1 mg L(-1)). The optimum constitution of MS medium was NAA 0.5 mg L(-1) + 6-BA 1 mg L(-1) for the growth of the stem tip of A. roxburghii, and NAA 1 mg L(-1) + 6-BA 2 mg L(-1) for the differentiation of bud and the formation of lateral branch of the stem section. The different concentrations of NAA and 6-BA had different effects on the growth and differentiation of the stem tip and the stem section of A. roxburghii.

Needle and stem wood production in Scots pine (Pinus sylvestris) trees of different age, size and competitive status.

PubMed

Vanninen, Petteri; Mäkelä, Annikki

2000-04-01

We studied effects of tree age, size and competitive status on foliage and stem production of 43 Scots pine (Pinus sylvestris L.) trees in southern Finland. The tree attributes related to competition included foliage density, crown ratio and height/diameter ratio. Needle mass was considered to be the primary cause of growth through photosynthesis. Both stem growth and foliage growth were strongly correlated with foliage mass. Consequently, differences in growth allocation between needles and stem wood in trees of different age, size, or position were small. However, increasing relative height increased the sum of stem growth and foliage growth per unit foliage mass, indicating an effect of available light. Suppressed trees seemed to allocate more growth to stem wood than dominant trees, and their stem growth per unit foliage mass was larger. Similarly, trees in dense stands allocated more growth to stem wood than trees in sparse stands. The results conformed to the pipe model theory but seemed to contradict the priority principle of allocation.

Potential effect of stand structure on belowground allocation

Treesearch

Thomas J. Dean

2001-01-01

Stand structure affects two key variables that affect biomass allocation to the stem: leaf area and height to the center of the crown. By translating wind forces into bending moment, these variables generate bending stress within a stem. The uniform stress axiom of stem formation can be used to calculate current stem mass for a given bending moment and stem allocation...

The Implementation of Cosine Similarity to Calculate Text Relevance between Two Documents

NASA Astrophysics Data System (ADS)

Gunawan, D.; Sembiring, C. A.; Budiman, M. A.

2018-03-01

Rapidly increasing number of web pages or documents leads to topic specific filtering in order to find web pages or documents efficiently. This is a preliminary research that uses cosine similarity to implement text relevance in order to find topic specific document. This research is divided into three parts. The first part is text-preprocessing. In this part, the punctuation in a document will be removed, then convert the document to lower case, implement stop word removal and then extracting the root word by using Porter Stemming algorithm. The second part is keywords weighting. Keyword weighting will be used by the next part, the text relevance calculation. Text relevance calculation will result the value between 0 and 1. The closer value to 1, then both documents are more related, vice versa.

Stem Cell-Derived Exosome in Cardiovascular Diseases: Macro Roles of Micro Particles.

PubMed

Yuan, Ye; Du, Weijie; Liu, Jiaqi; Ma, Wenya; Zhang, Lai; Du, Zhimin; Cai, Benzhi

2018-01-01

The stem cell-based therapy has emerged as the promising therapeutic strategies for cardiovascular diseases (CVDs). Recently, increasing evidence suggest stem cell-derived active exosomes are important communicators among cells in the heart via delivering specific substances to the adjacent/distant target cells. These exosomes and their contents such as certain proteins, miRNAs and lncRNAs exhibit huge beneficial effects on preventing heart damage and promoting cardiac repair. More importantly, stem cell-derived exosomes are more effective and safer than stem cell transplantation. Therefore, administration of stem cell-derived exosomes will expectantly be an alternative stem cell-based therapy for the treatment of CVDs. Furthermore, modification of stem cell-derived exosomes or artificial synthesis of exosomes will be the new therapeutic tools for CVDs in the future. In addition, stem cell-derived exosomes also have been implicated in the diagnosis and prognosis of CVDs. In this review, we summarize the current advances of stem cell-derived exosome-based treatment and prognosis for CVDs, including their potential benefits, underlying mechanisms and limitations, which will provide novel insights of exosomes as a new tool in clinical therapeutic translation in the future.

Mesenchymal stem cells induce dermal fibroblast responses to injury

PubMed Central

Smith, Andria N.; Willis, Elise; Chan, Vincent T.; Muffley, Lara A.; Isik, F. Frank; Gibran, Nicole S.; Hocking, Anne M.

2009-01-01

Although bone marrow-derived mesenchymal stem cells have been shown to promote repair when applied to cutaneous wounds, the mechanism for this response remains to be determined. The aim of this study was to determine the effects of paracrine signaling from mesenchymal stem cells on dermal fibroblast responses to injury including proliferation, migration and expression of genes important in wound repair. Dermal fibroblasts were co-cultured with bone marrow-derived mesenchymal stem cells grown in inserts, which allowed for paracrine interactions without direct cell contact. In this co-culture model, bone marrow-derived mesenchymal stem cells regulate dermal fibroblast proliferation, migration and gene expression. When co-cultured with mesenchymal stem cells, dermal fibroblasts show increased proliferation and accelerated migration in a scratch assay. A chemotaxis assay also demonstrated that dermal fibroblasts migrate towards bone marrow-derived mesenchymal stem cells. A PCR array was used to analyze the effect of mesenchymal stem cells on dermal fibroblast gene expression. In response to mesenchymal stem cells, dermal fibroblasts up-regulate integrin alpha 7 expression and down-regulate expression of ICAM1, VCAM1 and MMP11. These observations suggest that mesenchymal stem cells may provide an important early signal for dermal fibroblast responses to cutaneous injury. PMID:19666021

Application of stem cells in targeted therapy of breast cancer: a systematic review.

PubMed

Madjd, Zahra; Gheytanchi, Elmira; Erfani, Elham; Asadi-Lari, Mohsen

2013-01-01

The aim of this systematic review was to investigate whether stem cells could be effectively applied in targeted therapy of breast cancer. A systematic literature search was performed for original articles published from January 2007 until May 2012. Nine studies met the inclusion criteria for phase I or II clinical trials, of which three used stem cells as vehicles, two trials used autologous hematopoetic stem cells and in four trials cancer stem cells were targeted. Mesenchymal stem cells (MSCs) were applied as cellular vehicles to transfer therapeutic agents. Cell therapy with MSC can successfully target resistant cancers. Cancer stem cells were selectively targeted via a proteasome-dependent suicide gene leading to tumor regression. Wnt/β-catenin signaling pathway has been also evidenced to be an attractive CSC-target. This systematic review focused on two different concepts of stem cells and breast cancer marking a turning point in the trials that applied stem cells as cellular vehicles for targeted delivery therapy as well as CSC-targeted therapies. Applying stem cells as targeted therapy could be an effective therapeutic approach for treatment of breast cancer in the clinic and in therapeutic marketing; however this needs to be confirmed with further clinical investigations.

[Bioethical challenges of stem cell tourism].

PubMed

Ventura-Juncá, Patricio; Erices, Alejandro; Santos, Manuel J

2013-08-01

Stem cells have drawn extraordinary attention from scientists and the general public due to their potential to generate effective therapies for incurable diseases. At the same time, the production of embryonic stem cells involves a serious ethical issue concerning the destruction of human embryos. Although adult stem cells and induced pluripotential cells do not pose this ethical objection, there are other bioethical challenges common to all types of stem cells related particularly to the clinical use of stem cells. Their clinical use should be based on clinical trials, and in special situations, medical innovation, both of which have particular ethical dimensions. The media has raised unfounded expectations in patients and the public about the real clinical benefits of stem cells. At the same time, the number of unregulated clinics is increasing around the world, making direct offers through Internet of unproven stem cell therapies that attract desperate patients that have not found solutions in standard medicine. This is what is called stem cells tourism. This article reviews this situation, its consequences and the need for international cooperation to establish effective regulations to prevent the exploitation of patients and to endanger the prestige of legitimate stem cell research.

Efficient expansion of human keratinocyte stem/progenitor cells carrying a transgene with lentiviral vector

PubMed Central

2013-01-01

Introduction The development of an appropriate procedure for lentiviral gene transduction into keratinocyte stem cells is crucial for stem cell biology and regenerative medicine for genetic disorders of the skin. However, there is little information available on the efficiency of lentiviral transduction into human keratinocyte stem/progenitor cells and the effects of gene transduction procedures on growth potential of the stem cells by systematic assessment. Methods In this study, we explored the conditions for efficient expansion of human keratinocyte stem/progenitor cells carrying a transgene with a lentiviral vector, by using the culture of keratinocytes on a feeder layer of 3 T3 mouse fibroblasts. The gene transduction and expansion of keratinocytes carrying a transgene were analyzed by Western blotting, quantitative PCR, and flow cytometry. Results Polybrene (hexadiamine bromide) markedly enhanced the efficiency of lentiviral gene transduction, but negatively affected the maintenance of the keratinocyte stem/progenitor cells at a concentration higher than 5 μg/ml. Rho-assiciated kinase (ROCK) inhibitor Y-27632, a small molecule which enhanced keratinocyte proliferation, significantly interfered with the lentiviral transduction into cultured human keratinocytes. However, a suitable combination of polybrene and Y-27632 effectively expanded keratinocytes carrying a transgene. Conclusions This study provides information for effective expansion of cultured human keratinocyte stem/progenitor cells carrying a transgene. This point is particularly significant for the application of genetically modified keratinocyte stem/progenitor stem cells in regenerative medicine. PMID:24406242