1,387 research outputs found
Analyses of Dental Pulp in Restored Teeth
Restored teeth were extracted from test animals at four time intervals (1 hour, 1 day, 1 week, and 3 months) following amalgam insertion. Extracted teeth were frozen in liquid nitrogen, cryo-fractured so as to expose the pulps and then freeze-dried. Pulps were analyzed for mercury content by energy dispersive spectrometry (EDS) and atomic absorption spectrophotometry (AAS). Mercury levels appeared below the detection limits of EDS but could be detected by AAS which showed the highest readings seven days after amalgam insertion
Phosphatidylinositol 3âkinase and Akt effectors mediate insulinâlike growth factorâI neuroprotection in dorsal root ganglia neurons
Insulinâlike growth factorâI (IGFâI) protects neurons of the peripheral nervous system from apoptosis, but the underlying signaling pathways are not well understood. We studied IGFâI mediated signaling in embryonic dorsal root ganglia (DRG) neurons. DRG neurons express IGFâI receptors (IGFâIR), and IGFâI activates the phosphatidylinositol 3âkinase (PI3K)/Akt pathway. High glucose exposure induces apoptosis, which is inhibited by IGFâI through the PI3K/Akt pathway. IGFâI stimulation of the PI3K/Akt pathway phosphorylates three known Akt effectors: the survival transcription factor cyclic AMP response element binding protein (CREB) and the proâapoptotic effector proteins glycogen synthase kinaseâ3ÎČ (GSKâ3ÎČ) and forkhead (FKHR). IGFâI regulates survival at the nuclear level through accumulation of phosphoâAkt in DRG neuronal nuclei, increased CREBâmediated transcription, and nuclear exclusion of FKHR. High glucose increases expression of the proâapoptotic Bcl protein Bim (a transcriptional target of FKHR). However, IGFâI does not regulate Bim or antiâapoptotic BclâxL protein expression levels, which suggests that IGFâI neuroprotection is not through regulation of their expression. High glucose also induces loss of the initiator caspaseâ9 and increases caspaseâ3 cleavage, effects blocked by IGFâI. These data suggest that IGFâI prevents apoptosis in DRG neurons by regulating PI3K/Akt pathway effectors, including GSKâ3ÎČ, CREB, and FKHR, and by blocking caspase activation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154325/1/fsb2fj041581fje.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154325/2/fsb2fj041581fje-sup-0001.pd
Quantitative analysis of cell types during growth and morphogenesis in Hydra
Tissue maceration was used to determine the absolute number and the distribution of cell types in Hydra. It was shown that the total number of cells per animal as well as the distribution of cells vary depending on temperature, feeding conditions, and state of growth. During head and foot regeneration and during budding the first detectable change in the cell distribution is an increase in the number of nerve cells at the site of morphogenesis. These results and the finding that nerve cells are most concentrated in the head region, diminishing in density down the body column, are discussed in relation to tissue polarity
Statistical Similarities Between WSAâENLIL+Cone Model and MAVEN in Situ Observations From November 2014 to March 2016
Normal solar wind flows and intense solar transient events interact directly with the upper Martian atmosphere due to the absence of an intrinsic global planetary magnetic field. Since the launch of the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, there are now new means to directly observe solar wind parameters at the planetâs orbital location for limited time spans. Due to MAVENâs highly elliptical orbit, in situ measurements cannot be taken while MAVEN is inside Marsâ magnetosheath. To model solar wind conditions during these atmospheric and magnetospheric passages, this research project utilized the solar wind forecasting capabilities of the WSAâENLIL+Cone model. The model was used to simulate solar wind parameters that included magnetic field magnitude, plasma particle density, dynamic pressure, proton temperature, and velocity during a four Carrington rotationâlong segment. An additional simulation that lasted 18 Carrington rotations was then conducted. The precision of each simulation was examined for intervals when MAVEN was in the upstream solar wind, that is, with no exospheric or magnetospheric phenomena altering in situ measurements. It was determined that generalized, extensive simulations have comparable prediction capabilities as shorter, more comprehensive simulations. Generally, this study aimed to quantify the loss of detail in longâterm simulations and to determine if extended simulations can provide accurate, continuous upstream solar wind conditions when there is a lack of in situ measurements.Plain Language SummaryIf we ever have a manned mission to Mars, one of the numerous concerns would be space weather conditions and their effects on spacecraft in flight. One particular element of space weather that we like to focus on is solar wind: plasma that is continuously emitted from the Sun. Solar wind can effect communication between Earth and spacecraft, GPS services, and other vital elements of space travel. We therefore want a good understanding of space weather and want to forecast conditions before ever traveling there. Currently, there are not always means to directly measure solar wind, so we rely on numerical models. In this study, we used the model called WSAâENLIL+Cone to compare its solar wind measurements and one of our spacecraft orbiting Mars to see how well it did and to see if we can rely on it for solar wind forecasts. As it turns out, the model can be used for forecasting baseline values of different solar wind parameters, for example, temperature, even with limited information. We show in this study that the WSAâENLIL+Cone model allows us to forecast solar wind conditions and helps us to understand what is going on at that seemingly barren planet.Key PointsGeneralized, extensive WEC model simulations provide analogous confidence levels and results as detailed, relatively short simulationsWSAâENLIL+Cone model succeeds at predicting fast solar wind radial velocityPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142959/1/swe20547.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142959/2/swe20547_am.pd
Polyacrylamide as an organic nitrogen source for soil microorganisms with potential effects on inorganic soil nitrogen in agricultural soil
Linear polyacrylamide (PAM) is gaining considerable acceptance as an effective anti-erosion
additive in irrigation water. The potential effects of repeated PAM application on soil microbial ecology
and the potential for biotransformation of this polymer in soils are not completely known. Untreated and
PAM-treated soils (coarse-silty, mixed, mesic Durixerollic Calciorthids) were collected from agricultural
fields near Kimberly, ID. Soils were analyzed to determine the effects of PAM treatment on bacterial
counts and inorganic N concentrations and the potential for PAM biotransformation. Culturable heterotrophic
bacterial numbers were significantly elevated in PAM-treated soil for the plot planted to potatoes;
this effect was not observed in the plot planted to dry pink beans. Total bacterial numbers, determined by
AODC, were not altered by PAM treatment in any of the soils sampled. Polyacrylamide-treated soil
planted to potatoes contained significantly higher concentrations of NO3 and NH 3 (36.7 ± 2.20 and
1.30 ± 0.3 mg kg-1 , respectively) than did untreated soil (10.7 ± 2.30 and 0.50 ± 0.02 mg kg-1, respectively).
For bean field soil there was no difference between treated and untreated soil inorganic N concentrations.
Enrichment cultures generated from PAM-treated and untreated soils utilized PAM as sole N
source, but not as sole C source. While the monomeric constituents of PAM, acrylamide and acrylic acid,
both supported bacterial growth as sole C source, the PAM polymer did not. Enrichment cultures that
used PAM for N exhibited amidase activity specific for PAM as well as smaller aliphatic amides. Utilization
of PAM for N, but not for C, indicates that ultimately PAM may be converted into long chain polyacrylate,
which may be further degraded by physical and biological mechanisms or be incorporated into
organic matter
Soil amidase activity in polyacrylamide-treated soils and potential activity toward common amide-containing pesticides
t Polyacrylamide (PAM) is currently used as
an irrigation water additive to significantly reduce the
amount of soil erosion that occurs during furrow irrigation
of crops. Elevated soil amidase activity specific toward
the large PAM polymer has been reported in
PAM-treated field soils; the substrate specificity of the
induced amidase is uncertain. PAM-treated and untreated
soils were assayed for their capacity to hydrolyze
the amide bond in carbaryl (Sevin), diphenamid
(Dymid), and naphthalene acetamide. Based on results
obtained with a soil amidase assay, there was no difference
between PAM-treated and untreated soils with respect
to the rate of amide bond hydrolysis of any of the
agrochemicals tested. It appears that under these assay
conditions the PAM-induced soil amidase is not active
toward the amide bonds within these molecules. However,
carbaryl was hydrolyzed by a different soil amidase.
To our knowledge, this is the first soil enzyme assay-based
demonstration of the hydrolysis of carbaryl
by a soil amidase
Polyacrylamide as a substrate for microbial amidase in culture and soil
High molecular weight, linear polyacrylamide (PAM) with anionic charge is added to agricultural
soils as an anti-erosion additive. Research indicates that soil microorganisms are able to utilize
PAM as a source of N and that inorganic N pools are altered in some PAM-treated soils. The potential
role of hydrolytic amidase activity in the microbial utilization of PAM for N was investigated. Intracellular
and extracellular amidase activity was measured over time in enrichment cultures which used
PAM as sole N source. Enzyme activity increased concomitant with cell growth and N removal from
PAM. Cell growth, N removal and amidase production were dependent upon readily-available C in the
medium. Amidase activity and substrate specificity were determined for PAM-utilizing enrichment cultures
exposed to various N sources. Polyacrylamide-specific amidase activity appears to be inducible,
and not constitutive, based on the lack of amidase activity in cultures supplied with only ammonium
nitrate for N versus substantial activity when PAM was added as an amendment with or without ammonium
nitrate. Cultures amended with propionamide exhibited amidase activity largely specific for
this small amide substrate, while cultures supplied with PAM as sole N source exhibited amidase activity
specific for formamide, propionamide and PAM. Amidase activity and substrate specificity were
determined for PAM-treated and untreated agricultural field soils. Polyacrylamide-specific amidase activity
was higher in PAM-treated soil (14.86 ± 14.0 pg NH4 released soil) than in untreated soil
(1.02 ± 2.3 pg NH4 released C I soil); activity specific for low molecular weight amides was slightly
elevated or unchanged in PAM-treated soil as compared with untreated soil
Functional and Biogenetical Heterogeneity of the Inner Membrane of Rat-Liver Mitochondria
Rat liver mitochondria were fragmented by a combined technique of swelling, shrinking, and sonication. Fragments of inner membrane were separated by density gradient centrifugation. They differed in several respects: electronmicroscopic appearance, phospholipid and cytochrome contents, electrophoretic behaviour of proteins and enzymatic activities.
Three types of inner membrane fractions were isolated. The first type is characterized by a high activity of metal chelatase, low activities of succinate-cytochrome c reductase and of glycerolphosphate dehydrogenase, as well as by a high phospholipid content and low contents of cytochromes aa3 and b.
The second type displays maximal activities of glycerolphosphate dehydrogenase and metal chelatase, but contains relatively little cytochromes and has low succinate-cytochrome c reductase activity.
The third type exhibits highest succinate-cytochrome c reductase activity, a high metal chelatase activity and highest cytochrome contents. However, this fraction was low in both glycerolphosphate dehydrogenase activity and phospholipid content. This fraction was also richest in the following enzyme activities: cytochrome oxidase, oligomycin-sensitive ATPase, proline oxidase, 3-hydroxybutyrate dehydrogenase and rotenone-sensitive NADH-cytochrome c reductase.
Amino acid incorporation in vitro and in vivo in the presence of cycloheximide occurs predominantly into inner membrane fractions from the second type.
These data suggest that the inner membrane is composed of differently organized parts, and that polypeptides synthesized by mitochondrial ribosomes are integrated into specific parts of the inner membrane
Evidence for Asphericity in the Type IIn Supernova 1998S
We present optical spectropolarimetry obtained at the Keck-II 10-m telescope
on 1998 March 7 UT along with total flux spectra spanning the first 494 days
after discovery (1998 March 2 UT) of the peculiar type IIn supernova (SN)
1998S. The SN is found to exhibit a high degree of linear polarization,
implying significant asphericity for its continuum-scattering environment.
Prior to removal of the interstellar polarization, the polarization spectrum is
characterized by a flat continuum (at p ~ 2%) with distinct changes in
polarization associated with both the broad (FWZI >= 20,000 km/s) and narrow
(unresolved, FWHM < 300 km/s) line emission seen in the total flux spectrum.
When analyzed in terms of a polarized continuum with unpolarized broad-line
recombination emission, an intrinsic continuum polarization of p ~ 3% results
(the highest yet found for a SN), suggesting a global asphericity of >= 45%
from the oblate, electron-scattering dominated models of Hoflich (1991). The
smooth, blue continuum evident at early times is shown to be inconsistent with
a reddened, single-temperature blackbody, instead having a color temperature
that increases with decreasing wavelength. Broad emission-line profiles with
distinct blue and red peaks are seen in the total flux spectra at later times,
perhaps suggesting a disk-like or ring-like morphology for the dense (n_e ~
10^7 cm^{-3}) circumstellar medium. Implications of the circumstellar
scattering environment for the spectropolarimetry are discussed, as are the
effects of uncertain removal of interstellar polarization.Comment: 25 pages + 2 tables + 14 figures, Submitted to The Astrophysical
Journa
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