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1

The Role of Naturally Occurring Stable Isotopes in Mass Spectrometry, Part II: The Instrumentation  

PubMed Central

In the second instalment of this tutorial, the authors explain the instrumentation for measuring naturally occurring stable isotopes, specifically the magnetic sector mass spectrometer. This type of instrument remains unrivalled in its performance for isotope ratio mass spectrometry (IRMS) and the reader is reminded of its operation and its technical advantages for isotope measurements.

Bluck, Les; Volmer, Dietrich A.

2013-01-01

2

The Role of Naturally Occurring Stable Isotopes in Mass Spectrometry, Part I: The Theory  

PubMed Central

In this tutorial, the authors explain how naturally occurring stable isotopes are contributing to experimentally determined mass spectra and how this information can be exploited in quantitative experiments, structural elucidation studies and tracer methodologies. The first instalment of this two part series focuses on the theoretical aspects of stable isotopes and the calculation of their distribution patterns.

Bluck, Les; Volmer, Dietrich A.

2013-01-01

3

Determination of minor isotope abundances in naturally occurring uranium materials. The tracing power of isotopic signatures for uranium.  

National Technical Information Service (NTIS)

The mass spectrometric determination of minor abundant isotopes, (sup 234)U and (sup 236)U in naturally occurring uranium materials requires instruments of high abundance sensitivity and the use of highly sensitive detection systems. In this study the the...

R. Ovaskainen

1999-01-01

4

``Clumped-isotope'' geochemistry---The study of naturally-occurring, multiply-substituted isotopologues  

Microsoft Academic Search

Clumped isotope geochemistry is concerned with the state of ordering of rare isotopes in natural materials. That is, it examines the extent to which rare isotopes (D, 13C, 15N, 18O, etc.) bond with or near each other rather than with the sea of light isotopes in which they swim. Abundances of isotopic `clumps' in natural materials are influenced by a

John M. Eiler

2007-01-01

5

“Clumped-isotope” geochemistry—The study of naturally-occurring, multiply-substituted isotopologues  

Microsoft Academic Search

Clumped isotope geochemistry is concerned with the state of ordering of rare isotopes in natural materials. That is, it examines the extent to which rare isotopes (D, 13C, 15N, 18O, etc.) bond with or near each other rather than with the sea of light isotopes in which they swim. Abundances of isotopic ‘clumps’ in natural materials are influenced by a

John M. Eiler

2007-01-01

6

Resolving temporal variation in vertebrate diets using naturally occurring stable isotopes  

Microsoft Academic Search

Assessments of temporal variation in diets are important for our understanding of the ecology of many vertebrates. Ratios\\u000a of naturally occurring stable isotopes in animal tissues are a combination of the source elements and tissue specific fractionation\\u000a processes, and can thus reveal dietary information. We review three different approaches that have been used to resolve temporal\\u000a diet variation through analysis

F. Dalerum; A. Angerbjörn

2005-01-01

7

Macro-distribution of naturally occurring alpha-emitting isotopes of U in the human skeleton  

Microsoft Academic Search

Argonne National Laboratory (ANL) exhumed the remains of two individuals who had received Pu by intravenous injection, performed Pu analysis on these remains, and then sent portions of individual bones to our laboratory. We analyzed these bone samples to determine the macro-distribution of naturally occurring alpha-emitting isotopes of U (²³⁴U and ²³⁸U). We found that the sacrum contained the highest

Narayani P. Singh; David B. Bennett; McDonald E. Wrenn

1987-01-01

8

Evaluated nuclear data files for the naturally-occurring isotopes of cadmium  

SciTech Connect

Comprehensive neutronic evaluated data files for the naturally-occurring isotopes of cadmium are deduced from experimental data and nuclear models, and presented in the ENDF/B-VI formats. Particular attention is given to those processes relevant to fuel-cycle and fission-product applications. Comparisons are made with prior evaluations of the cadmium isotopes, and discrepancies and consistencies cited. Some of the discrepancies are very large 9.9 as much as 100%), and the differences have the potential for a pronounced impact on applications usage. The present files are comprehensive, including may important processes that are not represented in the contemporary ENDF/B-VI system. Recommendations are made for future measurements where appropriate.

McCabe, J. [Arizona Univ., Tucson, AZ (United States). Dept. of Nuclear and Energy Engineering; Smith, A.B. [Arizona Univ., Tucson, AZ (United States). Dept. of Nuclear and Energy Engineering]|[Argonne National Lab., IL (United States); Meadows, J.W. [Argonne National Lab., IL (United States)

1993-06-01

9

“Clumped-isotope” geochemistry—The study of naturally-occurring, multiply-substituted isotopologues  

NASA Astrophysics Data System (ADS)

Clumped isotope geochemistry is concerned with the state of ordering of rare isotopes in natural materials. That is, it examines the extent to which rare isotopes (D, 13C, 15N, 18O, etc.) bond with or near each other rather than with the sea of light isotopes in which they swim. Abundances of isotopic 'clumps' in natural materials are influenced by a wide variety of factors. In most cases, their concentrations approach (within ca. 1%, relative) the amount expected for a random distribution of isotopes. Deviations from this stochastic distribution result from: enhanced thermodynamic stability of heavy-isotope 'clumps'; slower kinetics of reactions requiring the breakage of bonds between heavy isotopes; the mass dependence of diffusive and thermo-gravitational fractionations; mixing between components that differ from one another in bulk isotopic composition; biochemical and photochemical fractionations that may reflect combinations of these simpler physical mechanisms; and, in some cases, other processes we do not yet understand. Although clumped isotope geochemistry is a young field, several seemingly promising applications have already emerged. Most importantly, it appears that proportions of 13C- 18O bonds in carbonate minerals are sensitive to their growth temperatures, independent of bulk isotopic composition. Thus, 'clumped isotope' analysis of ancient carbonates can be used as a quantitative paleothermometer that requires no assumptions about the ? 18O of waters from which carbonates grew. This approach has been used to reconstruct marine temperatures across the Phanerozoic (reaching back to the Silurian), terrestrial ground temperatures across the Cenozoic, thermal histories of aqueously altered meteorites, among other applications. Clumped isotope geochemistry is also placing new constraints on the atmospheric budget and stratospheric photochemistry of CO 2, and should be capable of placing analogous new constraints on the budgets of other atmospheric gases. Finally, this field could be extended to encompass sulfates, volatile hydrocarbons, organic moieties and other materials.

Eiler, John M.

2007-10-01

10

APPLICATION OF THE NATURALLY-OCCURRING DEUTERIUM ISOTOPE TO TRACING THE CAPILLARY FRINGE  

EPA Science Inventory

Naturally-occurring deuterium is a useful tracer of subsurface hydrologic processes. A possible application includes the identification of capillary fringes in the vadose zone. Multiple and discontinuous water tables persist in many temperate regions, under various hydrogeologi...

11

Radiometric method for determining concentration of naturally occurring isotopes and device therefor  

SciTech Connect

The proposed method essentially consists in that a sample of a substance is placed between two scintillators in immediate contact therewith whereupon said sample is hermetically sealed. Arranged in close proximity to each scintillator is a photomultiplier tube recording ionizing ..cap alpha..- and b-radiation. A selector is utilized to select pulses corresponding to ..cap alpha..- and b-particles, and delayed coincidence circuits of a recording element separate and record b-..cap alpha.. and ..cap alpha..-..cap alpha.. cascade pairs of delayed coincidences of RaC, ThC, and AcA radionuclides. Flows are measured twice at a predetermined time interval to account for emanation build-up tendency and concentration of isotopes of radium is determined from a formula.

Yakubovich, S.L.; Gerling, V.E.; Golubnichy, V.V.; Kotsen, M.E.; Stepanov, J.N.

1984-10-09

12

Naturally Occurring Anthracyclines  

NASA Astrophysics Data System (ADS)

The present article gives an overview of the natural occurring anthracyclines and anthracyclinones reported from microorganisms. A general description, discussion of their physicochemical properties, including NMR increments, and their structural classification are reported. In addition to a compilation of their sugar moieties, an exhaustive list of naturally occurring anthracyclines and anthracyclinones has been added.

Laatsch, Hartmut; Fotso, Serge

13

Comparing naturally occurring stable isotopes of nitrogen, carbon, and strontium as markers for the rearing locations of Atlantic salmon ( Salmo salar )  

Microsoft Academic Search

We compared the success of using naturally occurring stable isotopes of N, C, and Sr as markers for the rearing locations of juvenile salmon. We analyzed the isotopic signatures (? 15 Na nd? 13C in muscle and scales and 87 Sr\\/86Sr in otoliths) of >200 juvenile Atlantic salmon (Salmo salar) from 12 tributaries of the Connecticut River, USA. Young salmon

Brian P. Kennedy; C. Page Chamberlain; Joel D. Blum; Keith H. Nislow; Carol L. Folt

2005-01-01

14

Comment on ``Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes''  

NASA Astrophysics Data System (ADS)

In their article “Existence of Long-Lived Isomeric States in Naturally-Occuring Neutron-Deficient Th Isotopes” [Phys. Rev. C 76, 021303 (2007)], Marinov fail to demonstrate that basic mass spectrometric protocols, such as abundance sensitivity, linearity, and freedom from possible interferences, have been met. In particular, the claim that four isomeric states of Th have been discovered, using an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS), with abundances from (1-10)×10-11 relative to Th232, cannot be accepted, given the known abundance sensitivities of other sector field mass spectrometers. Accelerator mass spectrometry is the only mass spectrometric methodology capable of measuring relative abundances of the magnitude claimed by Marinov

Barber, R. C.; de Laeter, J. R.

2009-04-01

15

"Naturally occurring asbestos  

NASA Astrophysics Data System (ADS)

The term asbestos refers to six silicate minerals from amphibole and serpentine groups. By definition, it consists in bundles of thin and flexible long fibers, with high-tensile strength, and chemical and heat resistance. In contrast to asbestos found within commercial products and mining, the specific term ''naturally occurring asbestos'' (NOA) refers to asbestiform minerals occurring within rocks or soils that can be released by human activities or weathering processes. The fact that the exposure to asbestos is related to lung pathologies is now widely demonstrated (e.g. asbestosis, mesothelioma and lung cancer). However, if health risks associated with exposure to NOA exist, they are not yet well documented. The crystallization of natural asbestos occurs in specific Mg-rich lithologies associated with peculiar structural and metamorphic conditions. By recognizing and combining such specific geologic criteria, the presence or the absence of asbestos in bedrock terrains can be reasonably predicted and maps of NOA hazard can be drawn. We present here new results of geological mapping and petrological study concerning the evaluation of the NOA hazard in the Alps and Corsica, in France. The three folds approach consists in (1) a determination of lithologies with potential NOA from a bibliographic compilation and extraction of target zones from a geological geodatabase (2) a geological mapping of the target zones followed by a petrological characterization of sampled asbestiform minerals in the laboratory (optical microscopy, TEM, SEM, and Raman spectroscopy technics), and (3) the drawing of the final map of NOA hazard, at regional-scale. Occurrence criteria can be retained as follows: 1. NOA are abundant in the internal zones of the Alps and Corsica, especially within ophiolitic complexes. Natural asbestos are mostly concentrated within ultramafic rocks but can also occur within basic lithologies such as Mg-metagabbros, metabasalts and meta-pillow-lavas, 2. Asbestos is commonly located within fractures, shear-bands or shear-planes, developed during late retrograde metamorphic history, 3. Tremolite-actinolite-type asbestos is abundant both in ultramafic and mafic rocks, 4. Natural asbestos occur in few places within the external zones of the Alps, especially within hercynian ophiolitic massifs or concentrated in late Alpine fractures affecting leptyno-amphibolic lithologies.

Cagnard, F.; Lahondère, D.; Blein, O.; Lahfid, A.; Wille, G.

2012-04-01

16

Naturally occurring cardiac glycosides.  

PubMed

Cardiac glycoside poisoning from the ingestion of plants, particularly of oleanders, occurs with reasonable frequency in tropical and subtropical areas. We have assessed a variety of plant specimens for their cardiac glycoside content by means of radioimmunoassays with antibodies that differ in their specificity for cardiac glycosides. Significant amounts of immunoreactive cardiac glycoside were found to be present in the ornamental shrubs: yellow oleander (Thevetia peruviana); oleander (Nerium oleander); wintersweet (Carissa spectabilis); bushman's poison (Carissa acokanthera); sea-mango (Cerbera manghas); and frangipani (Plumeria rubra); and in the milkweeds: redheaded cotton-bush (Asclepias curassavica); balloon cotton (Asclepias fruiticosa); king's crown (Calotropis procera); and rubber vine (Cryptostegia grandifolia). The venom gland of the cane toad (Bufo marinus) also contained large quantities of cardiac glycosides. The competitive immunoassay method permits the rapid screening of specimens that are suspected to contain cardiac glycosides. Awareness of the existence of these plant and animal toxins and their dangers allows them to be avoided and poisoning prevented. The method is also useful for the confirmation of the presence of cardiac glycosides in serum in cases of poisoning. PMID:3086679

Radford, D J; Gillies, A D; Hinds, J A; Duffy, P

1986-05-12

17

Compilation of Minimum and Maximum Isotope Ratios of Selected Elements in Naturally Occurring Terrestrial Materials and Reagents.  

National Technical Information Service (NTIS)

This report summarizes reported variations in the isotopic compositions of 20 elements that are due to physical and chemical fractionation processes (not due to radioactive decay) and their effects on the standard atomic weight uncertainties.

T. B. Coplen J. A. Hopple J. K. Boehike H. S. Peiser S. E. Rieder

2002-01-01

18

Caffeine, a naturally occurring acaricide.  

PubMed

Since caffeine is a plant alkaloid that has been described as a naturally occurring insecticide, its acaricidal effect on Dermatophagoides pteronyssinus (Dp) was investigated. Twelve cultures were established by adding 30 Dp to 200 mg of Tetramin fish food and brewer's yeast (8:2 ratio); six cultures were treated with 20 mg of finely ground caffeine. All 12 cultures were incubated at 75% relative humidity, 25 degrees C, and observed during 8 weeks. Live mites were then counted under a stereoscope, cultures were extracted, and supernatants were analyzed for Der p I and Der f I allergen content with a two-site monoclonal RIA. Live mite counts in untreated cultures varied from 146 to 274 (215 +/- 47.1), and in caffeine-treated cultures from 0 to 3 (1 +/- 1.2; p less than or equal to 0.0001). Der p I concentrations in untreated cultures varied from 588 to 9000 ng/gm (3138.3 +/- 2990.8 ng/gm), and in caffeine-treated cultures from 52 to 117 ng/gm (78 +/- 23.8 ng/gm; p less than or equal to 0.01). Der p I was not detected in the food media or caffeine; Der f I was not detected in any of the cultures. Results demonstrate that caffeine inhibits mite growth and allergen production. PMID:1991914

Russell, D W; Fernández-Caldas, E; Swanson, M C; Seleznick, M J; Trudeau, W L; Lockey, R F

1991-01-01

19

Inactivation of Naturally Occurring Enteroviruses.  

National Technical Information Service (NTIS)

The goal of this project was to compare the kinetics of chlorine inactivation of a naturally-shed virus and its tissue culture grown counterpart. Since inactivation studies require purified preparation possessing high infectivity titer and low chlorine de...

A. R. Beasley W. Lichter L. L. Wellham

1980-01-01

20

INACTIVATION OF NATURALLY OCCURRING ENTEROVIRUSES  

EPA Science Inventory

The goal of this project was to compare the kinetics of chlorine inactivation of a naturally-shed virus and its tissue culture grown counterpart. Since inactivation studies require purified preparation possessing high infectivity titer and low chlorine demand a major part of this...

21

Naturally occurring, optically driven, cellular rotor  

NASA Astrophysics Data System (ADS)

We report the conversion of optical energy into mechanical energy by naturally occurring red blood cells (RBCs) placed in an optical trap. A trapped RBC undergoes folding due to the elastic nature of its cell membrane. On use of circularly polarized light in the trap, the folded RBCs rotate, indicating their birefringence. The cellular rotation speed depends on the size of the blood cells and on laser power. Rotating RBCs have implications for naturally occurring, optically driven, rotary micromachines.

Dharmadhikari, J. A.; Roy, S.; Dharmadhikari, A. K.; Sharma, S.; Mathur, D.

2004-12-01

22

Purifying food-grade, naturally occurring COâ  

Microsoft Academic Search

Technology to purify naturally occurring COâ into products suitable for enhanced oil recovery (EOR) and food grade COâ markets has been commercially demonstrated in a 20 MMscfd (1,100 ton\\/day) COâ processing facility owned and operated by Columbia Hydrocarbon Corp. The unit demonstrates that it is technically and economically feasible to process low grade natural gas to produce pipeline specification natural

J. E. Nobles; J. W. Stancik

1983-01-01

23

Naturally occurring genetic variation in Arabidopsis thaliana  

Microsoft Academic Search

Currently, genetic variation is probably the most important basic resource for plant biology. In addition to the variation artificially generated by mutants in model plants, naturally occurring genetic variation is extensively found for most species, including Arabidopsis. In many cases, natural variation present among accessions is multigenic, which has historically hampered its analysis. However, the exploitation of this resource down

Maarten Koornneef; Carlos Alonso-Blanco; Dick Vreugdenhil

2004-01-01

24

Naturally occurring antimicrobials for minimally processed foods.  

PubMed

Natural antimicrobials are gaining increased interest from researchers and food manufacturers alike seeking to discover label-friendly alternatives to the widely implemented synthetic compounds. Naturally occurring antimicrobials can be applied directly to food to protect food quality, extend food shelf life by inhibiting or inactivating spoilage microorganisms, and improve food safety by inhibiting or inactivating food-borne pathogens. There are a great number of natural antimicrobials derived from animal, plant, and microbial sources. This manuscript reviews their efficacy against spoilage and pathogenic organisms, their methods of evaluation, and their application in various foods as well as the development of novel delivery systems and incorporation with other hurdles. PMID:23244398

Davidson, P Michael; Critzer, Faith J; Taylor, T Matthew

2012-12-05

25

Deuterium Content of Naturally Occurring Water  

Microsoft Academic Search

THE deuterium content of naturally occurring water has so far been determined by two methods-from the mass-spectrogram of the hydrogen derived from it; and from the specific gravity of deuterium-free water. The former method1 gave for the abundance ratio H\\/D the value 5000 +\\/-500, while two discrepant values2,3 have been obtained by the latter, namely 9000 and 5750+\\/-250.

A. J. Edwards; R. P. Bell; J. H. Wolfenden

1935-01-01

26

Cocaine as a naturally occurring insecticide.  

PubMed Central

Although cocaine has a fascinating and complex medicinal history in man, its natural function in plants is unknown. The present studies demonstrate that cocaine exerts insecticidal effects at concentrations which occur naturally in coca leaves. Unlike its known action on dopamine reuptake in mammals, cocaine's pesticidal effects are shown to result from a potentiation of insect octopaminergic neurotransmission. Amine-reuptake blockers of other structural classes also exert pesticidal activity with a rank order of potency distinct from that known to affect vertebrate amine transporters. These findings suggest that cocaine functions in plants as a natural insecticide and that octopamine transporters may be useful sites for targeting pesticides with selectivity toward invertebrates. Images Fig. 3

Nathanson, J A; Hunnicutt, E J; Kantham, L; Scavone, C

1993-01-01

27

Leaching of technologically enhanced naturally occurring radioactive materials.  

PubMed

A form of waste associated with mining activities is related to the type of deposit being mined and to the procedure of exploitation and enrichment adopted. The wastes usually contain relatively large amounts of technologically enhanced naturally occurring radioactive materials (TENORM). The TENORM are often stored on the surface. Consequently, they can be leached as a result of interaction with aqueous solutions of different chemical composition. This further leads to pollution of water and soil in the vicinity of the stored wastes. The paper presents the results of laboratory investigation aimed at quantifying the leaching process of samples originating from uranium dumps and storage reservoirs associated with brine pumped from coal mines. The leaching process was investigated with respect to selected elements: uranium isotopes, radium isotopes, iron, barium and sodium. The samples were exposed to aqueous solutions of different chemical composition. The experiments revealed that TENORM in form of sulphate compounds are the most resistant against leaching. The leaching coefficient for radium isotopes varies from a few thousandth percent to a few hundredth percent. On the other hand, for TENORM occurring in sand or sludge, the leaching coefficient for uranium and radium isotopes ranged from a few hundredth percent to a few percent. PMID:17482828

Chau, Nguyen Dinh; Chru?ciel, Edward

2007-03-27

28

Naturally occurring, physiologically normal, primate chimeras  

PubMed Central

Callitrichids, South American primates including marmosets and tamarins, have evolved a unique physiology. Twins share a placenta during gestation and exchange stem cells, resulting in naturally occurring chimeric adults. Our study used a quantitative PCR-based assay to address whether this chimerism was restricted to blood and other cells of the hematopoietic lineage or whether it extended to other somatic tissues. These studies help to characterize species that have adapted evolutionarily to pervasive chimerism, with every individual healthy and unperturbed. This experiment of evolution offers insight into transplantation and histocompatibility, reproductive biology and behavior, and innate and adaptive immunity.

Sweeney, Carolyn; Ward, Joshua; Vallender, Eric J.

2012-01-01

29

Gold: compositional variations of naturally occurring alloys  

SciTech Connect

Naturally occurring gold is nearly always alloyed with silver, quantities of which may reach 40 or more percent, and frequently contains minor amounts of copper and mercury and traces of other metals. An extensive literatures search of analyses of gold alloys from world-wide localities, supplemented by several hundred additional electron microprobe analyses, yields the distribution pattern in terms of fineness (((Au)/(Au+Ag) wt %) x 1000). These data reveal few compositions in the range 0-500 fine and a maximum at approximately 920 fine. The near absence of compositions in the 0-500 fineness range and a few examples of coexisting silver and electrum (540 fine) suggest the existence of a miscibility gap at low temperatures. Copper contents generally increase with higher fineness; several natural examples reveal exsolution of cuprian gold and thus indicate another miscibility gap. Natural mercury contents are generally below 0.5 wt %, but placer gold grains commonly reveal surface contamination of mercury lost in streams by former recovery operations. Thin, sharply defined rims of very high fineness gold commonly have developed on placer gains in streams and soil zones.

Craig, J.R.; Rimstidt, J.D.

1985-01-01

30

Some naturally occurring phytophototoxins for mosquito control.  

PubMed

Alpha-terthiophene (alpha-T) and erythrosin-B, the naturally occurring plant secondary metabolites, were tried for their phototoxic properties against Anopheles and Culex larvae under dark, ordinary tube light (1.9-2.4 w/m2) and sun light (680-840 w/m2). LC50 values of alpha-T for Anopheles larvae (4th instar) were found to be 154, 92 and 11 ppb under dark, tube light and sunlight, respectively. For Culex larvae corresponding LC50 values under different light conditions were 129, 97 and 22 ppb. Erythrosin-B under all photoregimens was found to be less toxic to larvae of both Anopheles and Culex sps. Also, the susceptibility of the mosquito species decreased with age, towards alpha-T and erythrosin-B. Cumulative effects in terms of delay in metamorphosis were also observed among survivors of such exposures. The effects of these compounds were also seen on the adults and developing unhatched embryos of a common aquatic snail (Lymnaea sps). The LC50 values of alpha-T for adults were found to be 39, 23 ppm and 77 ppb under dark, tube light and sunlight and for developing unhatched embryos the corresponding values were 620, 41 and 13 ppb. Erythrosin-B was found to be much less toxic under sunlight and dark, to both adults and embryos as compared to the toxicity of alpha-T. Potential use of such biodegradable and eco-friendly compounds of natural origin in mosquito control is discussed. PMID:7821985

Sharma, A; Goel, H C

1994-10-01

31

Naturally occurring contamination in the Mancos Shale.  

PubMed

Some uranium mill tailings disposal cells were constructed on dark-gray shale of the Upper Cretaceous Mancos Shale. Shale of this formation contains contaminants similar to those in mill tailings. To establish the contributions derived from the Mancos, we sampled 51 locations in Colorado, New Mexico, and Utah. Many of the groundwater samples were saline with nitrate, selenium, and uranium concentrations commonly exceeding 250,?000, 1000, and 200 ?g/L, respectively. Higher concentrations were limited to groundwater associated with shale beds, but were not correlated with geographic area, stratigraphic position, or source of water. The elevated concentrations suggest that naturally occurring contamination should be considered when evaluating groundwater cleanup levels. At several locations, seep water was yellow or red, caused in part by dissolved organic carbon concentrations up to 280 mg/L. Most seeps had (234)U to (238)U activity ratios greater than 2, indicating preferential leaching of (234)U. Seeps were slightly enriched in (18)O relative to the meteoric water line, indicating limited evaporation. Conceptually, major ion chemical reactions are dominated by calcite dissolution following proton release from pyrite oxidation and subsequent exchange by calcium for sodium residing on clay mineral exchange sites. Contaminants are likely released from organic matter and mineral surfaces during weathering. PMID:22225529

Morrison, Stan J; Goodknight, Craig S; Tigar, Aaron D; Bush, Richard P; Gil, April

2012-01-20

32

Naturally Occurring Radioactive Materials in Cargo at US Borders  

SciTech Connect

In the U.S. and other countries, large numbers of vehicles pass through border crossings each day. The illicit movement of radioactive sources is a concern that has resulted in the installation of radiation detection and identification instruments at border crossing points. This activity is judged to be necessary because of the possibility of an act of terrorism involving a radioactive source that may include any number of dangerous radionuclides. The problem of detecting, identifying, and interdicting illicit radioactive sources is complicated by the fact that many materials present in cargo are somewhat radioactive. Some cargo contains naturally occurring radioactive material or technologically-enhanced naturally occurring radioactive material that may trigger radiation portal monitor alarms. Man-made radioactive sources, especially medical isotopes, are also frequently observed and produce alarms. Such nuisance alarms can be an operational limiting factor for screening of cargo at border crossings. Information about the nature of the radioactive materials in cargo that can interfere with the detection of radionuclides of concern is necessary. This paper provides such information for North American cargo, but the information may also be of use to border control officials in other countries. (PIET-43741-TM-361)

Kouzes, Richard T.; Ely, James H.; Evans, John C.; Hensley, Walter K.; Lepel, Elwood A.; McDonald, Joseph C.; Schweppe, John E.; Siciliano, Edward R.; Strom, Daniel J.; Woodring, Mitchell L.

2006-01-01

33

The photodegradation of some naturally occurring polymers  

Microsoft Academic Search

This review contains a discussion of how chemical and spectroscopic methods have been used to unravel the complex photodegradation processes that occur when wool and paper (made from high yield pulps) are exposed to light. Both materials yellow when exposed to UV light and are bleached by visible light. In addition, both materials are bleached when irradiated in solutions of

R. S. Davidson

1996-01-01

34

Naturally Occurring Fish Poisons from Plants  

ERIC Educational Resources Information Center

|The fish poisons derived from plants used throughout the world, not only as piscicides but also for a range of other uses, including insecticident and in folk medicines, is presented. The aim of this review is to provide a useful background for students interested in natural products.|

Cannon, Jonathan G.; Burton, Robert A.; Wood, Steven G.; Owen, Noel L.

2004-01-01

35

Bioassay of naturally occurring allelochemicals for phytotoxicity  

Microsoft Academic Search

The bioassay has been one of the most widely used tests to demonstrate allelopathic activity. Often, claims that a particular plant species inhibits the growth of another are based entirely on the seed germination response to solvent extracts of the suspected allelopathic plant; few of these tests are of value in demonstrating allelopathy under natural conditions. The veracity of the

Gerald R. Leather; Frank A. Einhellig

1988-01-01

36

Naturally occurring gold nanoparticles and nanoplates  

NASA Astrophysics Data System (ADS)

During the weathering of gold deposits, exceptionally pure,<200 nm diameter, nanoparticulate gold plates (6 nm thick)are formed. The particles display controlled growth of bothsize and shape and signs of assembly to form belts and sheets.The gold is associated and inter-grown with minerals formedby evaporation and is interpreted to have been deposited rapidlyfrom saline groundwater during a drying event. The size andmorphology of the gold nanoparticles and nanoplates are identicalto the products of experimentally manufactured gold colloids.This represents the first direct observation of colloidal nanoparticulategold in nature, confirming this as an active mechanism of goldtransport during the weathering of gold deposits.

Hough, R. M.; Noble, R. R. P.; Hitchen, G. J.; Hart, R.; Reddy, S. M.; Saunders, M.; Clode, P.; Vaughan, D.; Lowe, J.; Gray, D. J.; Anand, R. R.; Butt, C. R. M.; Verrall, M.

2008-07-01

37

Dog Models of Naturally Occurring Cancer  

PubMed Central

Studies using dogs provide an ideal solution to the gap in animal models of natural disease and translational medicine. This is evidenced by approximately 400 inherited disorders being characterized in domesticated dogs, most of which are relevant to humans. There are several hundred isolated populations of dogs (breeds) and each has vastly reduced genetic variation compared to humans; this simplifies disease mapping and pharmacogenomics. Dogs age five to eight-fold faster than humans, share environments with their owners, are usually kept until old age, and receive a high level of health care. Farseeing investigators recognized this potential and, over the last decade, developed the necessary tools and infrastructure to utilize this powerful model of human disease, including the sequencing of the dog genome in 2005. Here we review the nascent convergence of genetic and translational canine models of spontaneous disease, focusing on cancer.

Rowell, Jennie L.; McCarthy, Donna O.; Alvarez, Carlos E.

2011-01-01

38

Stable isotope deltas: tiny, yet robust signatures in nature.  

PubMed

Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including (14)C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. (13)C, (2)H, and (18)O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as-25 per mil can be written as-25 mUr (or-2.5 cUr or-0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg 'units' are easily included (e.g. either+0.015 ‰ or+15 per meg can be written as+15 ?Ur. PMID:22462621

Brand, Willi A; Coplen, Tyler B

2012-03-30

39

Stable isotope deltas: Tiny, yet robust signatures in nature  

USGS Publications Warehouse

Although most of them are relatively small, stable isotope deltas of naturally occurring substances are robust and enable workers in anthropology, atmospheric sciences, biology, chemistry, environmental sciences, food and drug authentication, forensic science, geochemistry, geology, oceanography, and paleoclimatology to study a variety of topics. Two fundamental processes explain the stable isotope deltas measured in most terrestrial systems: isotopic fractionation and isotope mixing. Isotopic fractionation is the result of equilibrium or kinetic physicochemical processes that fractionate isotopes because of small differences in physical or chemical properties of molecular species having different isotopes. It is shown that the mixing of radioactive and stable isotope end members can be modelled to provide information on many natural processes, including 14C abundances in the modern atmosphere and the stable hydrogen and oxygen isotopic compositions of the oceans during glacial and interglacial times. The calculation of mixing fractions using isotope balance equations with isotope deltas can be substantially in error when substances with high concentrations of heavy isotopes (e.g. 13C, 2H, and 18O ) are mixed. In such cases, calculations using mole fractions are preferred as they produce accurate mixing fractions. Isotope deltas are dimensionless quantities. In the International System of Units (SI), these quantities have the unit 1 and the usual list of prefixes is not applicable. To overcome traditional limitations with expressing orders of magnitude differences in isotope deltas, we propose the term urey (symbol Ur), after Harold C. Urey, for the unit 1. In such a manner, an isotope delta value expressed traditionally as?25 per mil can be written as?25 mUr (or?2.5 cUr or?0.25 dUr; the use of any SI prefix is possible). Likewise, very small isotopic differences often expressed in per meg ‘units’ are easily included (e.g. either+0.015 ‰ or+15 per meg can be written as+15 ?Ur.

Brand, Willi A.; Coplen, Tyler B.

2012-01-01

40

Analysis of natural-occurring and synthetic sexual hormones in sludge-amended soils by matrix solid-phase dispersion and isotope dilution gas chromatography-tandem mass spectrometry.  

PubMed

A sensitive analytical method is presented for the simultaneous determination of four synthetic estrogens and six steroid hormones in sludge-amended soil. The method employs matrix solid-phase dispersion (MSPD) followed by isotope dilution gas chromatography-tandem mass spectrometry injecting a large volume sample (10?L) after trimethylsilyl derivatization, using the solvent vent mode. It affords good resolution, high sensitivity and reproducibility and freedom from interferences even from complex matrices as soil amended with sewage sludge. The limits of detection (LODs) ranged from 10 to 300pgg(-1) with testosterone and progesterone having the highest limits. Soil amended with sewage sludge was spiked at 2, 10, 25 and 50ngg(-1) and the recoveries after MSPD with acetonitrile:methanol (90:10, v/v), ranged from 80 to 110% with relative standard deviations ?9%. The method was applied to the analysis of six soil samples collected from agricultural plots and forested fields that had been amended with sewage sludge using isotopically labeled surrogates. Three of the synthetic estrogens studied were found at least in one of the six samples analyzed and trans-androsterone and estrone were the only natural hormones detected, although at very low levels (?0.4ngg(-1)). PMID:23465128

Albero, Beatriz; Sánchez-Brunete, Consuelo; Miguel, Esther; Pérez, Rosa A; Tadeo, José L

2013-02-08

41

Stable Carbon Isotopic Signatures and Fractionations Occurring During Fungal Biosynthesis of Methyl Chloride  

NASA Astrophysics Data System (ADS)

Methyl halides are responsible for approximately 25% of the equivalent chlorine involved in stratospheric ozone depletion, yet quantitative understanding of their atmospheric budgets is still incomplete. The use of an isotopic mass balance to constrain these budgets is currently being investigated. The utility of this approach will depend not only on being able to measure the source signatures and loss kinetic isotope effects contributing to their atmospheric budgets, but also in our ability to assess the variability in these terms. Natural methyl halide sources and sinks due to microbial cycling, combined with their large and variable associated isotopic effects, should have discernable effects on the global atmospheric signature of these gases. Thus, we have begun investigating the isotopic signatures of methyl halides produced by fungi, and the fractionations occurring during their biosynthesis, using controlled laboratory cultures. Measurements of the stable carbon isotopic signatures of growth medium, biomass, respired CO2, CH3Cl, and the carbon mass balance were made over the growth cycle of Inonotus andersonii, a wood-rot fungus previously shown to emit methyl halides. Resulting CH3Cl ? 13C signatures were enriched by approximately 10\\permil as compared to those previously reported for Phellinus pomaceus, another wood-rot species1. Fractionations between substrate and biomass \\{? s-b\\}, as well as biomass and gases \\{? b-g\\}, were nearly constant during exponential and early stationary phase growth. Biomass was depleted by 1\\permil compared to the 13C malt extract medium, and CH3Cl and CO2 were depleted by up to 5\\permil compared to the biomass, implying the bulk of the final CH3Cl signature is determined during CH3Cl synthesis and not during uptake of the carbon substrate. However, the magnitude of these fractionations, and the direction of ? s-b, probably depends on the complexity of the substrate. Additionally, a survey of isotopic signatures of CH3Cl produced by several fungal species on C3 and C4 substrates was begun to quantify likely variability in the natural source signature. 1 Harper, DB., R.M. Kalin, J.T.G. Hamilton, and C. Lamb, Carbon Isotope Ratios for Chloromethane of Biological Origin: Potential Tool in Determining Biological Emissions, Environ. Sci.Technol., 35, 3616-3619, 2001.

Shaw, S. L.; Henn, M. R.; Chapela, I. H.; Conrad, M. E.; Goldstein, A. H.

2003-12-01

42

Effects of Confirmed and Disconfirmed Expectations: A Naturally Occurring Experiment.  

National Technical Information Service (NTIS)

The existence of a naturally occurring event (the selection of students for an honors program) permitted a test of cognitive dissonance theory through falsification. Affective reactions to confirmed and disconfirmed expectations were measured using both q...

J. E. Skivington R. W. Woodman

1984-01-01

43

Boron isotope variations in nature: a synthesis  

Microsoft Academic Search

The large relative mass difference between the two stable isotopes of boron, 10B and 11B, and the high geochemical reactivity of boron lead to significant isotope fractionation by natural processes. Published 11B values (relative to the NBS SRM-951 standard) span a wide range of 90. The lowest 11B values around — 30 are reported for non-marine evaporite minerals and certain

S. Barth

1993-01-01

44

Naturally Occurring Animal Models with Outer Retina Phenotypes  

PubMed Central

Naturally occurring and laboratory generated animal models serve as powerful tools with which to investigate the etiology of human retinal degenerations, especially retinitis pigmentosa (RP), Leber congenital amaurosis (LCA), cone dystrophies (CD) and macular degeneration (MD). Much progress has been made in elucidating gene defects underlying disease, in understanding mechanisms leading to disease, and in designing molecules for translational research and gene-based therapy to interfere with the progression of disease. Key to this progress has been study of naturally occurring murine and canine retinal degeneration mutants. This article will review the history, phenotypes and gene defects of select animal models with outer retina (photoreceptor and retinal pigment epithelium) degeneration phenotypes.

Baehr, Wolfgang; Frederick, Jeanne M.

2009-01-01

45

Controlled fermentation of kimchi using naturally occurring antimicrobial agents.  

PubMed

Kimchi is a traditional Korean fermented food. Since it ferments continuously during distribution and storage, the extension of shelf life by preventing over-acidification is a major concern in the kimchi industry. One of the most frequently attempted ways to delay fermentation is to add naturally occurring antimicrobial agents. Many researchers have investigated ways to delay over-acidification by adding minor ingredients, fruits or fruit seed extracts, extracts of medicinal herbs, culinary herbs and spices, and other miscellaneous substances to kimchi. The addition of naturally occurring antimicrobial agents may enhance the acceptability of kimchi to consumers over a longer period of time but may also have a disadvantage in that it may cause changes in sensory quality, especially if added in large amounts. To avoid undesirable sensory changes, application of hurdle technologies (i.e., multifactor preservative systems) which involve using combinations of low amounts of various naturally occurring antimicrobial agents as ingredients should be explored with the goal of controlling fermentation. If synergistic or additive antimicrobial effects can be achieved using small amounts of a combination of natural agents, changes in sensory qualities will be minimized, thereby prolonging shelf life. Research findings summarized in this review provide a basis for developing effective hurdle technologies using naturally occurring antimicrobial agents to extend shelf life of kimchi and perhaps other types of traditional fermented foods. PMID:22850370

Kim, Jinsol; Bang, Jihyun; Beuchat, Larry R; Kim, Hoikyung; Ryu, Jee-Hoon

2012-05-29

46

Pathology of Immunodeficient Mice With Naturally Occurring Murine Norovirus Infection  

Microsoft Academic Search

Murine norovirus (MNV) was recently discovered in Rag2?\\/?\\/Stat1?\\/? mice in a U.S. medical research facility. Presently, little is known concerning the epidemiology and natural history of this virus. We studied the pathology of naturally occurring MNV infection in 28 immunodeficient mice of several different genotypes (Rag1?\\/?\\/IFN? R?\\/? ,O T1Rag1?\\/?\\/IFN? R?\\/? ,O T2Rag1?\\/?\\/IFN? R?\\/?, Rag1?\\/?\\/Stat1?\\/?, and Rag2?\\/?) that were maintained in

JERROLD M. WARD; CHRISTIANE E. WOBUS; LARISSA B. THACKRAY; CINDY R. EREXSON; LARRY J. FAUCETTE; Gaël Belliot; ELYSSA L. BARRON; Stanislav Sosnovtsev; Kim Green

2006-01-01

47

Synthetic procedures for the preparation of deuterium-labeled analogs of naturally occurring steroids  

SciTech Connect

The object of this article is to review the procedures that have been published concerning the preparation of deuterium-labeled analogs of naturally occurring steroid hormones. In combination with mass spectrometric methods, these stable isotope-labeled compounds should be applicable for human metabolism studies or as internal standards. Deuteration techniques for the elucidation of stereochemical problems, procedures for the preparation of monodeuterated steroids, and synthesis of deuterated analogs of nonbiologic steroids have therefore not been included in this review. 41 refs.

Wudy, S.A. (Universitaetskinderklinik Ulm, Donau (Germany, F.R.))

1990-10-01

48

Measuring and Modeling Naturally Occurring Radioactive Material: Interpreting the Relationship Between the Natural Radionuclides Present  

SciTech Connect

The regulatory release of sites and facilities (property) for restricted or unrestricted use has evolved beyond prescribed levels to model-derived dose and risk based limits. Dose models for deriving corresponding soil and structure radionuclide concentration guidelines are necessarily simplified representations of complex processes. A conceptual site model is often developed to present a reasonable and somewhat conservative representation of the physical and chemical properties of the impacted material. Dose modeling software is then used to estimate resulting dose and/or radionuclide specific acceptance criteria (activity concentrations). When the source term includes any or all of the uranium, thorium or actinium natural decay series radionuclides the interpretation of the relationship between the individual radionuclides of the series is critical to a technically correct and complete assessment of risk and/or derivation of radionuclide specific acceptance criteria. Unlike man-made radionuclides, modeling and measuring naturally occurring radioactive material (NORM) and technologically enhanced NORM (TENORM) source terms involves the interpretation of the relationship between the radionuclide present, e.g., secular equilibrium, enrichment, depletion or transient equilibrium. Isotopes of uranium, radium, and thorium occur in all three natural decay series. Each of the three series also produces a radon gas isotope as one of its progeny. In nature, the radionuclides in the three natural decay series are in a state that is approaching or has achieved secular equilibrium, in which the activities of all radionuclides within each series are nearly equal. However, ores containing the three natural decay series may begin in approximate secular equilibrium, but after processing, equilibrium may be broken and certain elements (and the radioactive isotopes of that element) may be concentrated or removed. Where the original ore may have contained one long chain of natural decay series radionuclides, the resulting TENORM source term may contain several smaller decay chains, each headed by a different longer lived member of the original series. This paper presents the anatomy of common TENORM source terms and the pitfalls of measuring, interpreting and modeling these source terms. Modeling TENORM with common software such as RESRAD is discussed. In summary: RESRAD modeling (dose assessments) to derive single radionuclide, dose based acceptance criteria, requires a good understanding of the physical, chemical and biological factors/input parameters applicable to the selected exposure scenario(s). When NORM or TENORM source terms are modeled, an additional understanding of the status of equilibrium, is necessary to accurately perform a dose assessment in support of dose based acceptance criteria. Historical information about the site processes/ores, selection of appropriate analytical analyses to identify key decay series radionuclide and a comprehensive review of the characterization data are needed to understand the equilibrium status of the decay series present. Once the source term has been characterized (in regards to relative activities of the radionuclides within a decay series) the source term must be input into RESRAD to reflect that status of equilibrium at time zero, or at the time since placement, if the characterization data reflects the equilibrium status of dated material. When the RESRAD output file is reviewed, depending on the time of maximum dose, DCGL values may be artificially high in value. Sum of fraction calculations, based on the status of equilibrium of each decay series, can also be used to assess the RESRAD results and develop an appropriate MARSSIM final status survey protocol. (authors)

Lombardo, A.J.; Mucha, A.F. [Safety and Ecology Corporation, 2800 Solway Road, Knoxville, TN (United States)

2008-07-01

49

Naturally occurring nitrostable compounds. I. Secondary amines in foodstuffs  

Microsoft Academic Search

A procedure is described for the analysis of naturally occurring secondary amines. Identification of tosylamide derivatives by gas liquid chromotography-man spectrometry is carried out after steam distillation and cleanup. Morpholine and dimethylamine are ubiquitous. Piperidine and pyrrolidine are found in plant-derived material. Other amines are found in smaller quantities.

George M. Singer; William Lijinsky

1976-01-01

50

Emissions of naturally occurring radioactivity: fireclay mine and refractory plant  

Microsoft Academic Search

Atmospheric emissions of naturally occurring radioactivity were measured at a fireclay mine and the associated plant that produces refractory brick products. The only significant radioactive emission from the mine was radon-222. An analysis of the ore radioactivity and surface area of the mine indicated that the radon released is comparable to that from any similar surface area of similar radioactivity.

1981-01-01

51

On the Role of Attention in Naturally Occurring Matching Relations  

ERIC Educational Resources Information Center

|Prior researchers have evaluated the efficacy of using the matching law to describe naturally occurring behavior-environment interactions. However, spurious matching could be obtained if the response and environmental event were correlated, even if the event did not reinforce the response. To assess the likelihood of obtaining spurious matching…

St. Peter, Claire C.; Vollmer, Timothy R.; Bourret, Jason C.; Borrero, Carrie S. W.; Sloman, Kimberly N.; Rapp, John T.

2005-01-01

52

The Assessment of Attachment in a Naturally Occurring Strange Situation.  

ERIC Educational Resources Information Center

|Patterns of attachment in preschool-age children were investigated in a nonexperimental, naturally occurring stressful situation. The sample included 86 families with at least one child 18 to 54 months of age. In each family, the mother planned to deliver another child in a hospital birthing center. Separation from the mother during admission was…

Hoyer, Paulette J.; Jacobson, Joseph L.

53

Synthetic muscle promoters: activities exceeding naturally occurring regulatory sequences  

Microsoft Academic Search

Relatively low levels of expression from naturally occurring promoters have limited the use of muscle as a gene therapy target. Myogenic restricted gene promoters display complex organization usually involving combinations of several myogenic regulatory elements. By random assembly of E-box, MEF-2, TEF-1, and SRE sites into synthetic promoter recombinant libraries, and screening of hundreds of individual clones for transcriptional activity

Xuyang Li; Eric M. Eastman; Ruxandra Draghia-Akli; Robert J. Schwartz

1999-01-01

54

Natural Transformation of Campylobacter jejuni Occurs Beyond Limits of Growth  

PubMed Central

Campylobacter jejuni is a human bacterial pathogen. While poultry is considered to be a major source of food borne campylobacteriosis, C. jejuni is frequently found in the external environment, and water is another well-known source of human infections. Natural transformation is considered to be one of the main mechanisms for mediating transfer of genetic material and evolution of the organism. Given the diverse habitats of C. jejuni we set out to examine how environmental conditions and physiological processes affect natural transformation of C. jejuni. We show that the efficiency of transformation is correlated to the growth conditions, but more importantly that transformation occurs at growth-restrictive conditions as well as in the late stationary phase; hence revealing that growth per se is not required for C. jejuni to be competent. Yet, natural transformation of C. jejuni is an energy dependent process, that occurs in the absence of transcription but requires an active translational machinery. Moreover, we show the ATP dependent ClpP protease to be important for transformation, which possibly could be associated with reduced protein glycosylation in the ClpP mutant. In contrast, competence of C. jejuni was neither found to be involved in DNA repair following DNA damage nor to provide a growth benefit. Kinetic studies revealed that several transformation events occur per cell cycle indicating that natural transformation of C. jejuni is a highly efficient process. Thus, our findings suggest that horizontal gene transfer by natural transformation takes place in various habitats occupied by C. jejuni.

Vegge, Christina S.; Br?ndsted, Lone; Ligowska-Marzeta, Malgorzata; Ingmer, Hanne

2012-01-01

55

Helium isotopic abundance variation in nature  

SciTech Connect

The isotopic abundance of helium in nature has been reviewed. This atomic weight value is based on the value of helium in the atmosphere, which is invariant around the world and up to a distance of 100,000 feet. Helium does vary in natural gas, volcanic rocks and gases, ocean floor sediments, waters of various types and in radioactive minerals and ores due to {alpha} particle decay of radioactive nuclides.

Holden, N.E.

1993-08-01

56

The characteristics of gas hydrates occurring in natural environment  

NASA Astrophysics Data System (ADS)

In the past few years, extensive analyses have been carried out for characterizing the natural gas hydrate samples from Cascadia, offshore Vancouver Island; Mallik, Mackenzie Delta; Mount Elbert, Alaska North Slope; Nankai Trough, offshore Japan; Japan Sea and offshore India. With the results obtained, it is possible to give a general picture of the characteristics of gas hydrates occurring in natural environment. Gas hydrate can occur in sediments of various types, from sands to clay, although it is preferentially enriched in sediments of certain types, for example coarse sands and fine volcanic ash. Most of the gas hydrates in sediments are invisible, occurring in the pores of the sediments, while some hydrates are visible, appearing as massive, nodular, planar, vein-like forms and occurring around the seafloor, in the fractures related to fault systems, or any other large spaces available in sediments. Although methane is the main component of most of the natural gas hydrates, C2 to C7 hydrocarbons have been recognized in hydrates, sometimes even in significant amounts. Shallow marine gas hydrates have been found generally to contain minor amounts of hydrogen sulfide. Gas hydrate samples with complex gas compositions have been found to have heterogeneous distributions in composition, which might reflect changes in the composition of the available gas in the surrounding environment. Depending on the gas compositions, the structure type of a natural gas hydrate can be structure I, II or H. For structure I methane hydrate, the large cages are almost fully occupied by methane molecules, while the small cages are only partly occupied. Methane hydrates occurring in different environments have been identified with almost the same crystallographic parameters.

Lu, H.; Moudrakovski, I.; Udachin, K.; Enright, G.; Ratcliffe, C.; Ripmeester, J.

2009-12-01

57

An Update on Antitumor Activity of Naturally Occurring Chalcones  

PubMed Central

Chalcones, which have characteristic 1,3-diaryl-2-propen-1-one skeleton, are mainly produced in roots, rhizomes, heartwood, leaves, and seeds of genera Angelica, Sophora, Glycyrrhiza, Humulus, Scutellaria, Parartocarpus, Ficus, Dorstenia, Morus, Artocarpus, and so forth. They have become of interest in the research and development of natural antitumor agents over the past decades due to their broad range of mechanisms including anti-initiation, induction of apoptosis, antiproliferation, antimetastasis, antiangiogenesis, and so forth. This review summarizes the studies on the antitumor activity of naturally occurring chalcones and their underlying mechanisms in detail during the past decades.

Zhang, En-Hui; Wang, Ru-Feng; Guo, Shu-Zhen; Liu, Bin

2013-01-01

58

Singlet oxygen quenching ability of naturally occurring carotenoids  

Microsoft Academic Search

The singlet oxygen quenching ability of various naturally occurring carotenoids was examined by measuring toluidine blue-sensitized\\u000a photooxidation of linoleic acid. To assess quenching, the oxidation of linoleic acid was followed by measuring oxygen consumption\\u000a and ultraviolet absorbance at 235 nm. We found that oxygen quenching increased as the number of conjugated double bonds in\\u000a the carotenoids increased, but quenching varied

Osamu Hirayama; Kyoko Nakamura; Syoko Hamada; Yoko Kobayasi

1994-01-01

59

Tribology of naturally occurring boric acid films on boron carbide  

Microsoft Academic Search

In this paper, we describe the formation and self-lubricating mechanisms of naturally occurring boric acid films on boron carbide (B4C) substrates. The sliding friction coefficients of yttria\\/partially stabilized zirconia pins against plain B4C substrates are quite high at 0.3–0.4, but are 6–10 times lower against the B4C substrates subjected to annealing at 800°C. We determined that this low friction was

A. Erdemir; C. Bindal; C. Zuiker; E. Savrun

1996-01-01

60

Biological and pharmacological activity of naturally occurring iridoids and secoiridoids.  

PubMed

The biological and pharmacological activities reported for naturally occurring iridoids and secoiridoids are reviewed. The hypothesis that iridoid glycoside and acetal esters can best be considered as pro-drugs and that corresponding hemiacetals and compounds derived from them carry the pharmacophores is discussed. The possibility that the activity of some iridoids is determined by their conversion to pyridine monoterpene alkaloids (PMTA) is also considered. The evidence available suggests that iridoids show activities consistent with those presented by immunomodulators and adaptogens. PMID:23195768

Ghisalberti, E L

1998-04-01

61

Prostaglandin E 2concentrations in naturally occurring canine cancer  

Microsoft Academic Search

The purpose of this study was to determine the PGE2concentration in naturally-occurring cancer in pet dogs and in canine cancer cell lines in order to identify specific types of canine cancer with high PGE2production which could serve as preclinical models to evaluate anticancer strategies targeting PGE2. PGE2concentrations were measured by enzyme immunoassay in canine melanoma, soft tissue sarcoma, transitional cell

S. I. Mohammed; K. Coffman; N. W. Glickman; M. G. Hayek; D. J. Waters; D. Schlittler; D. B. DeNicola; D. W. Knapp

2001-01-01

62

Histopathology of Naturally Occurring and Surgically Induced Osteoarthritis in Mice  

PubMed Central

Objective The morphology of lesions in mouse models of osteoarthritis (OA) has not been comprehensively characterized, in part because current histological assessments of OA focus primarily on articular cartilage. In the present study, sections of murine stifle joints with naturally occurring (aged animals) and surgically induced (destabilized medial meniscus, DMM) OA were examined using a newly developed histological grading scheme that includes quantitative measurements and semiquantitative grades to evaluate multiple joint tissues. Design The data collected was analyzed using Principal Components Analysis (PCA); factor scores for each joint were generated. Individual parameters and factor scores were compared between surgical groups and among age groups. For comparison, the original Mankin Histological-Histochemical Grading System (HHGS) also was applied. Results Overall, lesions were most severe in the medial tibial plateaus. Significant changes in articular cartilage and neighboring bone were identified in surgically induced models and in naturally occurring disease. Mean factor scores provided a comprehensive evaluation of joint changes. An important new finding was that chondrocyte cell death within the articular cartilage was a commonly identified lesion and its extent significantly increased with age. While the Mankin HHGS detected significant overall differences in OA severity between surgical groups, it was not sensitive in detecting age related differences, nor did it provide information regarding changes in individual tissues. Conclusion These results demonstrate the utility of this newly developed murine OA grading scheme in identifying lesions in articular cartilage and in other joint tissues. Surgically induced changes were similar to those occurring naturally with aging.

McNulty, Margaret A.; Loeser, Richard F.; Davey, Cynthia; Callahan, Michael F.; Ferguson, Cristin M.; Carlson, Cathy S.

2012-01-01

63

Natural and artificial alpha radioactivity of platinum isotopes  

Microsoft Academic Search

The partial alpha emission half-life for the naturally occurring and artificially produced platinum isotopes (Z=78) was evaluated in the framework of a semiempirical, one-parameter model based on the quantum mechanical tunneling mechanism through a Coulomb-plus-centrifugal-plus-overlapping potential barrier within the spherical nucleus approximation. This approach has been shown to be exceptionally well suited (to a level of 90% of the cases

O. A. P. Tavares; E. L. Medeiros

2011-01-01

64

Structural study on a naturally occurring terphenyl quinone.  

PubMed

Two terphenyl quinones were synthesized for a structural study on a naturally occurring biologically active terphenyl quinone. 3-Methoxy-5,6-diphenylcyclohexa-3,5-dien-1,2-dione, a possible structure proposed by our analysis of the NMR spectra, was synthesized by Suzuki-Miyaura coupling and subsequent oxidation of the resulting substituted phenol, although not being identical to the natural product. Recently isolated 3-methoxy-2,5-diphenylcyclohexa-2,5-dien-1,4-dione was synthesized from a commercially available 2,5-diphenyl-1,4-benzoquinone in three steps in a good overall yield, and its NMR spectra were identical to those of the natural product. PMID:23832350

Nakazaki, Atsuo; Huang, Wen-Yu; Koga, Kazushi; Yingyongnarongkul, Boon-ek; Boonsombat, Jutatip; Sawayama, Yusuke; Tsujimoto, Takashi; Nishikawa, Toshio

2013-07-07

65

Purifying food-grade, naturally occurring CO/sub 2/  

SciTech Connect

Technology to purify naturally occurring CO/sub 2/ into products suitable for enhanced oil recovery (EOR) and food grade CO/sub 2/ markets has been commercially demonstrated in a 20 MMscfd (1,100 ton/day) CO/sub 2/ processing facility owned and operated by Columbia Hydrocarbon Corp. The unit demonstrates that it is technically and economically feasible to process low grade natural gas to produce pipeline specification natural gas, raw CO/sub 2/, and food grade CO/sub 2/. The Selexol treating facility is located on a reclaimed coal strip mine with very restricted plot area. Only compression and dehydration equipment for the CO/sub 2/ is located there. The CO/sub 2/ is transported by pipeline to the Marmet site, approx. 7 miles away. This site contains the facilities for purifying the CO/sub 2/ and for storage.

Nobles, J.E.; Stancik, J.W.

1983-12-26

66

Maedi-visna: the meningoencephalitis in naturally occurring cases.  

PubMed

Lesions were examined at different levels of the central nervous system (CNS) in 64 sheep with natural maedi-visna (MV) meningoencephalitis. All animals showed lesions in more than one of the CNS locations examined; the lesions in the cranial regions were periventricular, while those in the spinal cord affected the white matter funicles. Lesions were found particularly in the cerebellar peduncles (non-suppurative meningoencephalitis), followed by the corpus callosum, hippocampus and thoracic spinal cord. Vascular, infiltrative and malacic histopathological patterns were recognized. One pattern predominated in each section examined, although mixed forms occurred. Vascular lesions occurred with similar frequency at all CNS levels, but infiltrative and malacic lesions predominated at rostral and caudal levels, respectively. Cells consistent with macrophages and shown immunohistochemically to be associated with MV virus were seen in malacic and infiltrative lesions, at the periphery of damaged areas. PMID:18922546

Benavides, J; García-Pariente, C; Fuertes, M; Ferreras, M C; García-Marín, J F; Juste, R A; Pérez, V

2008-10-14

67

Transmission of Naturally Occurring Lymphoma in Macaque Monkeys  

NASA Astrophysics Data System (ADS)

Spontaneously occurring rhesus monkey lymphomas were transmitted into healthy rhesus monkeys by using tumor cell suspensions. The naturally arising tumors included an immunoblastic sarcoma and an undifferentiated lymphoma. Recipient animals developed undifferentiated lymphomas, poorly differentiated lymphomas, or parenchymal lymphoproliferative abnormalities suggestive of early lesions of lymphoma. Some of these animals developed such opportunistic infections as cytomegalovirus hepatitis and cryptosporidiosis. They also showed evidence of an abnormal circulating peripheral blood mononuclear cell. These findings, all characteristic of the acquired immune deficiency syndrome (AIDS) of macaques, suggest a link between these transmissible lymphomas and AIDS in macaque monkeys.

Hunt, Ronald D.; Blake, Beverly J.; Chalifoux, Laura V.; Sehgal, Prabhat K.; King, Norval W.; Letvin, Norman L.

1983-08-01

68

Naturally occurring genetic variation affects Drosophila photoreceptor determination  

Microsoft Academic Search

The signal transduction pathway controlling determination of the identity of the R7 photoreceptor in the Drosophila eye is shown to harbor high levels of naturally occurring genetic variation. The number of ectopic R7 cells induced by the\\u000a dosage-sensitive Sev\\u000a \\u000a S11.1\\u000a transgene that encodes a mildly activated form of the Sevenless tyrosine kinase receptor is highly sensitive to the wild-type\\u000a genetic

Patricia J. Polaczyk; Robert Gasperini; Greg Gibson

1998-01-01

69

Emissions of naturally occuring radioactivity: Stauffer elemental phosphorus plant  

SciTech Connect

Naturally occurring radioactivity was measured in the atmospheric emissions and process materials of a thermal phosphate (elemental phosphorus) plant. Representative exhaust stack samples were collected from each process in the plant. The phosphate ore contained about 120 parts per million uranium. The radioactivity emitted in greatest quantity was radon-222 with an annual release from the plant of 8.3 curies. Emissions of lead-210 and polonium-210 were measured at 280 and 200 millicuries per year. Annual emissions of each of the other radionuclides of the uranium decay chain were estimated to be 4.2 millicuries. The slag pile was determined not to be a source of radon.

Andrews, V.E.

1982-11-01

70

Emissions of naturally occurring radioactivity: fireclay mine and refractory plant  

SciTech Connect

Atmospheric emissions of naturally occurring radioactivity were measured at a fireclay mine and the associated plant that produces refractory brick products. The only significant radioactive emission from the mine was radon-222. An analysis of the ore radioactivity and surface area of the mine indicated that the radon released is comparable to that from any similar surface area of similar radioactivity. The major particulate radioactivity from the refractory operation was polonium-210, released as the brick was fired. Approximately 26 percent of the polonium-210 in green brick was driven off in the kilns.

Andrews, V.E.

1981-02-01

71

Oxygen Isotope Evidence for the Extra-Terrestrial Origin of the First Natural Quasicrystal  

NASA Astrophysics Data System (ADS)

SIMS oxygen-isotopic data indicate that the first naturally occurring quasicrystal is associated with a diverse assemblage of high-temperature refractory chondritic minerals (silicates and oxides) formed in the early solar system.

Guan, Y.; Bindi, L.; Eiler, J. M.; Hollister, L.; MacPherson, G. J.; Steinhardt, P. J.; Yao, N.

2011-03-01

72

Thermal resistance of naturally occurring airborne bacterial spores.  

PubMed Central

Simulation of a heat process used in the terminal dry-heat decontamination of the Viking spacecraft is reported. Naturally occurring airborne bacterial spores were collected on Teflon ribbons in selected spacecraft assembly areas and subsequently subjected to dry heat. Thermal inactivation experiments were conducted at 105, 111.7, 120, 125, 130, and 135 degrees C with a moisture level of 1.2 mg of water per liter. Heat survivors were recovered at temperatures of 135 degrees C when a 30-h heating cycle was employed. Survivors were recovered from all cycles studied and randomly selected for identification. The naturally occurring spore population was reduced an average of 2.2 to 4.4 log cycles from 105 to 135 degrees C. Heating cycles of 5 and 15 h at temperature were compared with the standard 30-h cycle at 111.7, 120, and 125 degrees C. No significant differences in inactivation (alpha = 0.05) were observed between 111.7 and 120 degrees C. The 30-h cycle differs from the 5-and 15-h cycles at 125 degrees C. Thus, the heating cycle can be reduced if a small fraction (about 10-3 to 10-4) of very resistant spores can be tolerated.

Puleo, J R; Bergstrom, S L; Peeler, J T; Oxborrow, G S

1978-01-01

73

Composition and structural aspects of naturally occurring ferrihydrite  

NASA Astrophysics Data System (ADS)

A series of naturally occurring ferrihydrites sampled from an acid mine drainage environment were characterized and compared with synthetic 2-line ferrihydrite using high energy X-ray total scattering and pair distribution function analysis, Scanning Transmission X-ray Microscopy (STXM), Transmission Electron Microscopy (TEM), BET N 2 surface area measurements, and chemical extractions in order to place constraints on their structural and physical properties as a function of composition. Overall, the short- and intermediate-range ordering of the natural samples is comparable to synthetic ferrihydrite. However, with increasing Al, Si, and organic matter contents, a decrease in particle size and an increase in structural disorder were observed. Silica is suspected to have a pronounced effect on the crystallinity of ferrihydrite as a result of its inhibitory effect on Fe polymerization and particle growth, and it is likely complexed at the surfaces of ferrihydrite nanoparticles. Aluminum, on the other hand may substitute for Fe 3+ in natural ferrihydrite. Organic matter is pervasive and intimately associated with ferrihydrite aggregates, and its presence during ferrihydrite precipitation may have contributed to additional structural disorder. The increase in impurity content affects not only the particle size and structural order of ferrihydrite but may also have a significant effect on its surface reactivity.

Cismasu, A. Cristina; Michel, F. Marc; Tcaciuc, A. Patricia; Tyliszczak, Tolek; Brown, Gordon E., Jr.

2011-02-01

74

Epigenetic Variation in Mangrove Plants Occurring in Contrasting Natural Environment  

PubMed Central

Background Epigenetic modifications, such as cytosine methylation, are inherited in plant species and may occur in response to biotic or abiotic stress, affecting gene expression without changing genome sequence. Laguncularia racemosa, a mangrove species, occurs in naturally contrasting habitats where it is subjected daily to salinity and nutrient variations leading to morphological differences. This work aims at unraveling how CpG-methylation variation is distributed among individuals from two nearby habitats, at a riverside (RS) or near a salt marsh (SM), with different environmental pressures and how this variation is correlated with the observed morphological variation. Principal Findings Significant differences were observed in morphological traits such as tree height, tree diameter, leaf width and leaf area between plants from RS and SM locations, resulting in smaller plants and smaller leaf size in SM plants. Methyl-Sensitive Amplified Polymorphism (MSAP) was used to assess genetic and epigenetic (CpG-methylation) variation in L. racemosa genomes from these populations. SM plants were hypomethylated (14.6% of loci had methylated samples) in comparison to RS (32.1% of loci had methylated samples). Within-population diversity was significantly greater for epigenetic than genetic data in both locations, but SM also had less epigenetic diversity than RS. Frequency-based (GST) and multivariate (?ST) methods that estimate population structure showed significantly greater differentiation among locations for epigenetic than genetic data. Co-Inertia analysis, exploring jointly the genetic and epigenetic data, showed that individuals with similar genetic profiles presented divergent epigenetic profiles that were characteristic of the population in a particular environment, suggesting that CpG-methylation changes may be associated with environmental heterogeneity. Conclusions In spite of significant morphological dissimilarities, individuals of L. racemosa from salt marsh and riverside presented little genetic but abundant DNA methylation differentiation, suggesting that epigenetic variation in natural plant populations has an important role in helping individuals to cope with different environments.

Lira-Medeiros, Catarina Fonseca; Parisod, Christian; Fernandes, Ricardo Avancini; Mata, Camila Souza; Cardoso, Monica Aires; Ferreira, Paulo Cavalcanti Gomes

2010-01-01

75

Laboratory observation of naturally occurring dust-density waves  

NASA Astrophysics Data System (ADS)

Dust-density waves are electrostatic compressional waves that propagate in dusty plasma. Compared to the more familiar ion-acoustic waves, in dust-density waves, inertia is provided by dust particles (instead of ions) while pressure is provided by the ions as well as electrons (not just electrons). In a laboratory experiment, we observed dust density waves in a 3D void-free dusty plasma. The waves occur naturally due to an ion-flow instability. Dust particles (4.8 microns) are levitated within the volume of a glass box that rests atop an electrode in a radio-frequency glow discharge plasma. Horizontal confinement of dust particles is provided by the plasma's natural electric field that is enhanced by the walls of the glass box, while vertical confinement is due to the electrode's sheath. We observed dust-density waves with planar wave fronts propagating in alignment with flowing ions. By directly imaging the dust particles with a 500 frame-per-second camera, we monitor the dust density modulations in both space and time. A typical wave propagates at 40 mm/s with a frequency of 24 Hz. In this work, we characterize these waves and their growth as they propagate.

Flanagan, Tim; Goree, John

2010-11-01

76

Assembly of naturally occurring glycosides, evolved tactics, and glycosylation methods.  

PubMed

Glycosylation of proteins and lipids is critical to many life processes. Secondary metabolites (or natural products), such as flavonoids, steroids, triterpenes, and antibiotics, are also frequently modified with saccharides. The resulting glycosides include diverse structures and functions, and some of them have pharmacological significance. The saccharide portions of the glycosides often have specific structural characteristics that depend on the aglycones. These molecules also form heterogeneous "glycoform" mixtures where molecules have similar glycosidic linkages but the saccharides vary in the length and type of monosaccharide unit. Thus, it is difficult to purify homogeneous glycosides in appreciable amounts from natural sources. Chemical synthesis provides a feasible access to the homogeneous glycosides and their congeners. Synthesis of a glycoside involves the synthesis of the aglycone, the saccharide, the connection of these two parts, and the overall manipulation of protecting groups. However, most synthetic efforts to date have focused on the aglycones, treating the attachment of saccharides onto the aglycones as a dispensable topic. The synthesis of the aglycone and the synthesis of the saccharide belong to two independent categories of chemistry, and different types of the aglycones and saccharides pose as specific synthetic subjects in their own disciplines. The only reaction that integrates the broad chemistry of glycoside synthesis is the glycosidic bond formation between the saccharide and the aglycone. Focusing on this glycosylation reaction in this Account, we string together our experience with the synthesis of the naturally occurring glycosides. We briefly describe the synthesis of 18 glycosides, including glycolipids, phenolic glycosides, steroid glycosides, and triterpene glycosides. Each molecule represents a prototypical structure of a family of the natural glycosides with interesting biological activities, and we emphasize the general tactics for the synthesis of these diverse structures. We provide a rationale for four tactics for the synthesis of glycosides, based on the stage at which the glycosidic bond is formed between the saccharide and the aglycone. This choice of tactic determines the success or failure of a synthesis, and the flexibility and the overall efficiency of the synthesis as well. Toward the synthesis of heterogeneous glycoform mixtures, we discuss successive and random glycosylation reactions. Finally, we have developed two new glycosylation protocols that address the challenges in the glycosylation of aglycones that are poorly nucleophilic, extremely acid labile, or extremely electrophilic. One of these new protocols takes advantage of glycosyl trifluoroacetimidate donors, and a second protocol uses gold(I)-catalyzed glycosylation with glycosyl ortho-alkynylbenzoate donors. PMID:22493991

Yu, Biao; Sun, Jiansong; Yang, Xiaoyu

2012-04-11

77

Natural abundance variations in stable isotopes and their potential uses in animal physiological ecology.  

PubMed

Chemical, biological, and physical processes lead to distinctive "isotopic signatures" in biological materials that allow tracing of the origins of organic substances. Isotopic variation has been extensively used by plant physiological ecologists and by paleontologists, and recently ecologists have adopted the use of stable isotopes to measure ecosystem patterns and processes. To date, animal physiological ecologists have made minimal use of naturally occurring stable isotopes as tracers. Here we provide a review of the current and potential uses of naturally occurring stable isotopes in animal physiological ecology. We outline the physical and biological processes that lead to variation in isotopic abundance in plants and animals. We summarize current uses in animal physiological ecology (diet reconstruction and animal movement patterns), and suggest areas of research where the use of stable isotopes can be fruitful (protein balance and turnover and the allocation of dietary nutrients). We argue that animal physiological ecologists can benefit from including the measurement of naturally occurring stable isotopes in their battery of techniques. We also argue that animal physiologists can make an important contribution to the emerging field of stable isotopes in biology by testing experimentally the plethora of assumptions upon which the techniques rely. PMID:9683412

Gannes, L Z; Martínez del Rio, C; Koch, P

1998-03-01

78

Naturally occurring mastitis disrupts developmental competence of bovine oocytes.  

PubMed

We examined the effects of naturally occurring mastitis on bovine oocyte developmental competence in vitro. Specifically, we investigated the effects of intramammary infection on the ovarian pool of oocytes (i.e., follicle-enclosed oocytes) and their ability to undergo in vitro maturation, fertilization, and further development to the blastocyst stage. Culled Holstein cows (n=50) from 9 commercial dairy farms in Israel were allotted to 3 groups according to somatic cell count (SCC) records of the last 3 monthly milk tests as well as of quarter samples collected before slaughter: (1) low SCC (n=7), (2) medium SCC (n=16), or (3) high SCC (n=27). Means of SCC values differed among low-, medium-, and high-SCC groups: 148,000, 311,000 and 1,813,000cell/mL milk, respectively. Milk yield and days in milk did not differ among the 3 groups. Bacterial isolates included coagulase-negative staphylococci, Escherichia coli, Streptococcus dysgalactiae, or no bacteria found. Ovaries were collected at the abattoir and brought to the laboratory. Cumulus oocyte complexes were recovered separately from each cow and subjected individually to in vitro maturation and fertilization, followed by 8d in culture. The number of aspirated oocytes did not differ among groups, with a range of 17 to 21 oocytes per cow. The proportion of oocytes that cleaved into 2- to 4-cell-stage embryos (86.1±3.4%) did not differ among groups. In contrast, mean percentages of embryos developed to the blastocyst stage on d 7 and 8 after fertilization were less in both medium- and-high SCC groups than in the low-SCC group (5.6±2.3 and 4.1±1.8 vs. 18.1±4.6%, respectively). Additional analysis indicated that cleavage and blastocyst-formation rates did not differ among the bacterial types in the low-, medium-, and high-SCC groups. These are the first results to demonstrate that naturally occurring mastitis disrupts the developmental competence of the ovarian pool of oocytes, (i.e., oocytes at the germinal vesicle stage). The disruption was associated with elevation of SCC rather than bacterial type. The results may provide a partial explanation for the low fertility of cows that have contracted mastitic pathogens before insemination. PMID:23957998

Roth, Z; Dvir, A; Kalo, D; Lavon, Y; Krifucks, O; Wolfenson, D; Leitner, G

2013-08-16

79

Naturally occurring minichromosome platforms in chromosome engineering: an overview.  

PubMed

Artificially modified chromosome vectors are non-integrating gene delivery platforms that can shuttle very large DNA fragments in various recipient cells: theoretically, no size limit exists for the chromosome segments that an engineered minichromosome can accommodate. Therefore, genetically manipulated chromosomes might be potentially ideal vector systems, especially when the complexity of higher eukaryotic genes is concerned. This review focuses on those chromosome vectors generated using spontaneously occurring small markers as starting material. The definition and manipulation of the centromere domain is one of the main obstacles in chromosome engineering: naturally occurring minichromosomes, due to their inherent small size, were helpful in defining some aspects of centromere function. In addition, several distinctive features of small marker chromosomes, like their appearance as supernumerary elements in otherwise normal karyotypes, have been successfully exploited to use them as gene delivery vectors. The key technologies employed for minichromosome engineering are: size reduction, gene targeting, and vector delivery in various recipient cells. In spite of the significant advances that have been recently achieved in all these fields, several unsolved problems limit the potential of artificially modified chromosomes. Still, these vector systems have been exploited in a number of applications where the investigation of the controlled expression of large DNA segments is needed. A typical example is the analysis of genes whose expression strictly depends on the chromosomal environment in which they are positioned, where engineered chromosomes can be envisaged as epigenetically regulated expression systems. A novel and exciting advance concerns the use of engineered minichromosomes to study the organization and dynamics of local chromatin structures. PMID:21431718

Raimondi, Elena

2011-01-01

80

Naturally occurring allele diversity allows potato cultivation in northern latitudes.  

PubMed

Potato (Solanum tuberosum L.) originates from the Andes and evolved short-day-dependent tuber formation as a vegetative propagation strategy. Here we describe the identification of a central regulator underlying a major-effect quantitative trait locus for plant maturity and initiation of tuber development. We show that this gene belongs to the family of DOF (DNA-binding with one finger) transcription factors and regulates tuberization and plant life cycle length, by acting as a mediator between the circadian clock and the StSP6A mobile tuberization signal. We also show that natural allelic variants evade post-translational light regulation, allowing cultivation outside the geographical centre of origin of potato. Potato is a member of the Solanaceae family and is one of the world's most important food crops. This annual plant originates from the Andean regions of South America. Potato develops tubers from underground stems called stolons. Its equatorial origin makes potato essentially short-day dependent for tuberization and potato will not make tubers in the long-day conditions of spring and summer in the northern latitudes. When introduced in temperate zones, wild material will form tubers in the course of the autumnal shortening of day-length. Thus, one of the first selected traits in potato leading to a European potato type is likely to have been long-day acclimation for tuberization. Potato breeders can exploit the naturally occurring variation in tuberization onset and life cycle length, allowing varietal breeding for different latitudes, harvest times and markets. PMID:23467094

Kloosterman, Bjorn; Abelenda, José A; Gomez, María del Mar Carretero; Oortwijn, Marian; de Boer, Jan M; Kowitwanich, Krissana; Horvath, Beatrix M; van Eck, Herman J; Smaczniak, Cezary; Prat, Salomé; Visser, Richard G F; Bachem, Christian W B

2013-03-06

81

A nitrogen and sulfur isotope investigation of redox conditions occurring in a shallow outwash aquifer.  

NASA Astrophysics Data System (ADS)

The sources and distribution of elevated nitrate and sulfate concentrations were determined using nitrogen and sulfur isotopes in groundwater from an unconfined outwash aquifer located in Jackson County, southern Indiana. Land use is mostly agricultural. Local farmers apply nitrogeneous inorganic fertilizers to their fields. In addition, two commercial confined feedlots house over two million chickens, and wastes are stored in seven interconnected lagoons at the larger feedlot. These wastes are later applied to an adjacent field via spray irrigation. Over 50 shallow wells (5 m deep), domestic wells (7 m deep) and deep wells (15to 20 m deep) were sampled over a two- year period to monitor nitrogen and sulfur inputs from these sources. Most shallow groundwater in the study area is above the EPA drinking water standards for nitrate-N (>10 mgL). Nitrate concentrations are highest down gradient from the spray irrigation field (53.5 mgL), yet are also elevated in up gradient groundwaters. Nitrogen isotopes are enriched in the heavier isotope (d15N-NO3 > +13.7 ooo) down gradient from the large feedlot and lightest signatures (d15N-NO3 < +2.0 ooo) are found in up gradient groundwater underlying fields that use inorganic fertilizers. Analytes associated with feedlot wastes (sodium, potassium, chloride and sulfate) are also elevated down gradient from the larger feedlot. Deep groundwater has no nitrate and higher sulfate concentrations than shallow waters. In two sets of multi-level wells, enrichment in both oxygen and nitrogen isotopes indicates that denitrification may occur at two depths: 1) locally in shallow waters adjacent to the waste lagoons; and 2) in deeper waters (approximately 10 m) throughout the study area. Sulfate isotopic signatures in deep groundwater approach the signature of pyrite found within the outwash (d34S-SO4 = -11.6 ooo). Autotrophic denitrification may be occurring where nitrate is reduced and the oxidation of pyrite is adding sulfate with depth.

Spalding, R.; Hartke, E.

2001-12-01

82

Prostaglandin E2 concentrations in naturally occurring canine cancer.  

PubMed

The purpose of this study was to determine the PGE2 concentration in naturally-occurring cancer in pet dogs and in canine cancer cell lines in order to identify specific types of canine cancer with high PGE2 production which could serve as preclinical models to evaluate anticancer strategies targeting PGE2. PGE2 concentrations were measured by enzyme immunoassay in canine melanoma, soft tissue sarcoma, transitional cell carcinoma, osteosarcoma, and prostatic carcinoma cell lines; in 80 canine tumor tissue samples including oral melanoma (MEL), oral squamous cell carcinoma (SCC), transitional cell carcinoma of the urinary bladder (TCC), lymphoma (LSA), mammary carcinoma (MCA), osteosarcoma (OSA), prostatic carcinoma (PCA); and in corresponding normal organ tissues. High concentrations of PGE(2)(range 400-3300 pg/10(4)cells) were present in cell culture medium from the transitional cell carcinoma, prostatic carcinoma, and osteosarcoma cell lines. PGE2 concentrations in tumor tissues were elevated (tumor PGE2 concentration>mean+2X sd PGE(2)concentration of normal organ tissue) in 21/22 TCC, 5/6 PCA, 7/10 SCC, 5/10 MEL, 3/8 MCA, 4/15 OSA, and 0/9 LSA. Results of this study will help guide future investigations of anticancer therapies that target cyclooxygenase and PGE2. PMID:11161579

Mohammed, S I; Coffman, K; Glickman, N W; Hayek, M G; Waters, D J; Schlittler, D; DeNicola, D B; Knapp, D W

2001-01-01

83

Properties and mechanisms of action of naturally occurring antifungal peptides.  

PubMed

Antimicrobial peptides are a vital component of the innate immune system of all eukaryotic organisms and many of these peptides have potent antifungal activity. They have potential application in the control of fungal pathogens that are a serious threat to both human health and food security. Development of antifungal peptides as therapeutics requires an understanding of their mechanism of action on fungal cells. To date, most research on antimicrobial peptides has focused on their activity against bacteria. Several antimicrobial peptides specifically target fungal cells and are not active against bacteria. Others with broader specificity often have different mechanisms of action against bacteria and fungi. This review focuses on the mechanism of action of naturally occurring antifungal peptides from a diverse range of sources including plants, mammals, amphibians, insects, crabs, spiders, and fungi. While antimicrobial peptides were originally proposed to act via membrane permeabilization, the mechanism of antifungal activity for these peptides is generally more complex and often involves entry of the peptide into the cell. PMID:23381653

van der Weerden, Nicole L; Bleackley, Mark R; Anderson, Marilyn A

2013-02-05

84

Ginsenosides Are Novel Naturally-Occurring Aryl Hydrocarbon Receptor Ligands  

PubMed Central

The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor that mediates many of the biological and toxicological actions of structurally diverse chemicals. In this study, we examined the ability of a series of ginsenosides extracted from ginseng, a traditional Chinese medicine, to bind to and activate/inhibit the AHR and AHR signal transduction. Utilizing a combination of ligand and DNA binding assays, molecular docking and reporter gene analysis, we demonstrated the ability of selected ginsenosides to directly bind to and activate the guinea pig cytosolic AHR, and to stimulate/inhibit AHR-dependent luciferase gene expression in a recombinant guinea pig cell line. Comparative studies revealed significant species differences in the ability of ginsenosides to stimulate AHR-dependent gene expression in guinea pig, rat, mouse and human cell lines. Not only did selected ginsenosides preferentially activate the AHR from one species and not others, mouse cell line was also significantly less responsive to these chemicals than rat and guinea pig cell lines, but the endogenous gene CYP1A1 could still be inducted in mouse cell line. Overall, the ability of these compounds to stimulate AHR signal transduction demonstrated that these ginsenosides are a new class of naturally occurring AHR agonists.

Hu, Qin; He, Guochun; Zhao, Jing; Soshilov, Anatoly; Denison, Michael S.; Zhang, Aiqian; Yin, Huijun; Fraccalvieri, Domenico; Bonati, Laura; Xie, Qunhui; Zhao, Bin

2013-01-01

85

Ginsenosides are novel naturally-occurring aryl hydrocarbon receptor ligands.  

PubMed

The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor that mediates many of the biological and toxicological actions of structurally diverse chemicals. In this study, we examined the ability of a series of ginsenosides extracted from ginseng, a traditional Chinese medicine, to bind to and activate/inhibit the AHR and AHR signal transduction. Utilizing a combination of ligand and DNA binding assays, molecular docking and reporter gene analysis, we demonstrated the ability of selected ginsenosides to directly bind to and activate the guinea pig cytosolic AHR, and to stimulate/inhibit AHR-dependent luciferase gene expression in a recombinant guinea pig cell line. Comparative studies revealed significant species differences in the ability of ginsenosides to stimulate AHR-dependent gene expression in guinea pig, rat, mouse and human cell lines. Not only did selected ginsenosides preferentially activate the AHR from one species and not others, mouse cell line was also significantly less responsive to these chemicals than rat and guinea pig cell lines, but the endogenous gene CYP1A1 could still be inducted in mouse cell line. Overall, the ability of these compounds to stimulate AHR signal transduction demonstrated that these ginsenosides are a new class of naturally occurring AHR agonists. PMID:23776647

Hu, Qin; He, Guochun; Zhao, Jing; Soshilov, Anatoly; Denison, Michael S; Zhang, Aiqian; Yin, Huijun; Fraccalvieri, Domenico; Bonati, Laura; Xie, Qunhui; Zhao, Bin

2013-06-11

86

Volatile analysis of ground almonds contaminated with naturally occurring fungi.  

PubMed

Aflatoxigenic aspergilli inflict major economic damage to the tree nut industry of California, with the highest negative impact to almonds. Aspergilli and fungi in general are known to emit volatiles in varying quantity and composition dependent upon their growth media. The goal of the study was to determine the volatile emission of whole and blanched almonds that had been picked out and labeled as inedible by processors. The aflatoxin content and number of colony forming units of each sample were also determined. A total of 23 compounds were consistently detected and identified. Several volatiles from the blanched almonds demonstrated significant increases when compared to the emissions of whole almonds. Several of these volatiles are considered fatty acid decomposition products and included hexanal, heptanal, octanal, nonanal, 3-octen-2-one, tetramethylpyrazine, and decanal. The almond samples investigated were characteristic of a typical postharvest environment and illustrative of potential contamination within a stockpile or transport container. Volatiles indicative of fatty acid decomposition were predominant in the samples that underwent some form of blanching. The emission amounts of hexanal, heptanal, octanal, and hexanoic acid increased 3-fold in samples contaminated with aflatoxin; however, due to variability between samples they could not be considered as indicator volatiles for aflatoxin content. The emission profile of volatiles from almond kernels contaminated with naturally occurring aspergilli and associated fungi is heretofore unreported. PMID:21528918

Beck, John J; Mahoney, Noreen E; Cook, Daniel; Gee, Wai S

2011-05-06

87

Effect of naturally occurring tetrapyrroles on photooxidation in cow's milk.  

PubMed

The objective of this work was to better understand the photosensitizing effect of riboflavin versus naturally occurring tetrapyrroles in cow's milk. This was done by exposure of milk samples to blue light (400-500 nm), which is absorbed by riboflavin and tetrapyrroles, orange light (575-750 nm), which is absorbed by tetrapyrroles but not riboflavin, and white light, which contains the entire visible region. The milk was exposed to about 1.6 W/m(2) in 20 h, and two different light sources were tested: HMI lamp and fluorescent light tubes used for commercial display. Sensory analysis showed that wavelengths longer than 575 nm induced significantly more off-flavors than wavelengths shorter than 500 nm. By fluorescence spectroscopy it was observed that tetrapyrroles, in particular, chlorophyllic compounds, were degraded more by orange light than by blue and that the degree of degradation correlated closely with the formation of sensory off-flavors. The fluorescent agent Singlet Oxygen Sensor Green (SOSG) was used to monitor the formation of singlet oxygen under the different light exposure conditions, and the method verified that singlet oxygen was formed in large proportions in milk exposed to wavelengths longer than 575 nm, presumably with minor or no involvement of riboflavin. The results suggest that cholorophyllic compounds are responsible for a major part of photooxidation in milk. It is also suggested that ?-carotene protects against photooxidation under blue light because it absorbs a major portion of the light below 500 nm and thereby reduces reactions with photosensitizers. PMID:21405085

Airado-Rodríguez, Diego; Intawiwat, Natthorn; Skaret, Josefine; Wold, Jens Petter

2011-03-15

88

Naturally occurring asbestos: a recurring public policy challenge.  

PubMed

The potential environmental hazards and associated public health issues related to exposure to respirable dusts from the vicinity of natural in-place asbestos deposits (commonly referred to as naturally occurring asbestos, NOA) have gained the regulatory and media spotlight in many areas around the United States, such as Libby, MT, Fairfax County, VA, and El Dorado Hills, CA, among others. NOA deposits may be present in a variety of geologic formations. It has been suggested that airborne asbestos may be released from NOA deposits, and absent appropriate engineering controls, may pose a potential health hazard if these rocks are crushed or exposed to natural weathering and erosion or to human activities that create dust. The issue that needs to be addressed at a policy level is the method of assessing exposures to elongated rock fragments ubiquitous in dust clouds in these same environments and the associated risk. Elongated rock fragments and single crystal minerals present in NOA have been construed by some as having attributes, including the health effects, of asbestos fibers. However, the Occupational Safety and Health Administration (OSHA), Mine Safety and Health Administration (MSHA), and the Consumer Products Safety Commission (CPSC) found that the scientific evidence did not support this assumption. As in many environmental fields of study, the evidence is often disputed. Regulatory policy is not uniform on the subject of rock fragments, even within single agencies. The core of the issue is whether the risk parameters associated with exposures to commercial asbestos can or should be applied to rock fragments meeting an arbitrary set of particle dimensions used for counting asbestos fibers. Inappropriate inclusion of particles or fragments results in dilution of risk and needless expenditure of resources. On the other hand, inappropriate exclusion of particles or fragments may result in increased and unnecessary risk. Some of the fastest growing counties in the United States are in areas where NOA is known to exist and therefore this issue takes on national significance. This ongoing national dilemma has raised public and business concerns. There has been continuing political and scientific debate and widespread miscommunication over perceived versus actual health risks, the validity of various analytical sampling and testing methods, the questionable necessity and escalating costs of remediation procedures, and the combined negative impact on numerous commercial and public interests. Thus, conflicting research and regulatory positions on the distinctions between and hazards of true asbestos and ordinary rock fragments is all that is presently available to the public until the differing scientific communities and government agencies arrive at a consensus on these issues. The risk assessment methodology and the analytical technology needed to support inferences drawn from existing research are available, but have not been organized and implemented in the manner needed to resolve the NOA controversy. There should exist nationally adopted and peer-reviewed NOA standards (developed jointly by the scientific community, health risk professionals, and government regulators) that establish: (1) a scientific basis for risk evaluation and assessment of NOA and rock fragments; (2) accepted analytical protocols for determining if NOA actually exists in a given area and for separating NOA from related non-asbestos rock fragments and single crystal minerals; and (3) effective public policies for managing NOA, minimizing potential hazards, and protecting public health. This article will review some of the key issues involved with the current NOA debate, propose improved analytical methodologies, describe potential solutions for dealing with NOA, and outline the benefits to be gained by creating a practical national NOA public policy. PMID:18180100

Lee, R J; Strohmeier, B R; Bunker, K L; Van Orden, D R

2007-11-28

89

Organic Food Production and Its Influence on Naturally Occurring Toxins  

Microsoft Academic Search

The levels of natural plant toxins and mycotoxins in foods may be influenced by the methods used (organic vs. conventional)\\u000a for agricultural production. Research findings suggest that organic foods may possess higher levels of natural plant toxins\\u000a than conventional foods based upon mechanistic similarities between natural plant toxin production and the production of plant\\u000a secondary metabolites of nutritional interest. Specific

Carl K. Winter

90

Biosynthesis of toxic naturally-occurring seafood contaminants.  

PubMed

Outbreaks of human illness caused by the consumption of contaminated seafood, continues to be a major problem particularly for the shellfish industry. Toxins from marine, brackish and freshwater environments, which are often produced as a result of harmful algal blooms, have been implicated as the causative agents of these poisonings. Commonly, poisoning events have been grouped into one of six classes, Paralytic Shellfish Poisoning (PSP), Diarrhetic Shellfish Poisoning (DSP), Neurotoxic Shellfish Poisoning (NSP), Ciguatera Fish Poisoning (CFP), Azaspiracid Shellfish Poisoning (AZP), and Amnesiac Shellfish Poisoning (ASP). The causative agents of these specific poisonings along with their biosyntheses are discussed in this review. The highly unusual and complex structures of most common seafood toxins have made them interesting targets for biosynthetic studies. Many of the toxins presented are biosynthesized via complex pathways that have been elucidated either through isotope labelled precursor feeding studies and/or characterization of the genes encoding the producing organism's biosynthetic machinery. Feeding studies key to our understanding of a particular toxin's biosynthesis, such as the incorporation of unusual precursors, as well as unique biosynthetic pathways and rare chemical mechanisms involved in the assembly process are highlighted. More recently, however, modern genomics-based techniques have been used for the elucidation of biosynthetic pathways and these are presented in the context of polyketide, non-ribosomal peptide, and hybrid pathway derived, toxin assembly. PMID:19761784

Kalaitzis, John A; Chau, Rocky; Kohli, Gurjeet S; Murray, Shauna A; Neilan, Brett A

2009-09-15

91

The enormous diversity and biotechnological potential of naturally occurring bacteria  

Microsoft Academic Search

Microbiologist are convinced that the 4000 validly described species represent only a minute fraction of the actually occurring number of prokaryotic species in the environment. The combined application of the polymerase chain reaction (PCR), commercially available sequencing kits and automated sequencing devices has facilitated and accelerated the determination of the phylogenetic position of any culturable and of most uncultured microorganisms.

Erko Stackebrandt

1998-01-01

92

THE LATEST NATURALLY OCCURING SUBSTANCES TO INCREASE INSULIN SENSITIVITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

A number of natural products have been reported to improve blood sugar in people with type 2 diabetes mellitus. The essential nutrient, chromium, has been known for more than four decades to improve insulin sensitivity. We reported more than five years ago that chromium improves the glucose, insul...

93

Specificity of Naturally Occurring Antibody in Normal Gibbon Serum  

Microsoft Academic Search

Gibbon natural antibody examined by immunoelectron microscopy reacted with the entire envelope of type C virus and with areas on the cell surface equivalent to or smaller than the diameter of a virion in gibbon and human culture cells infected with or releasing type C viruses. The antibody activity was absorbed completely by two cell cultures infected with gibbon ape

Tadao Aoki; Margaret Liu; Mary Jane Walling; Grace S. Bushar; Phyllis B. Brandchaft; Thomas G. Kawakami

1976-01-01

94

Naturally occurring vertical transmission of Neospora caninum in dogs  

Microsoft Academic Search

Vertical transmission of Neospora caninum was studied in naturally infected, privately owned dogs, using antibody detection by IFAT to identify infected individuals. Retrospective studies were undertaken in litters from six bitches of the Hamiltonstövare breed, and on litters from seven bitches of other breeds—in both cases following diagnosis of clinical disease in puppies—and prospective studies were carried out on 17

J. S. Barber; A. J. Trees

1998-01-01

95

Overview of naturally occurring Earth materials and human health concerns  

NASA Astrophysics Data System (ADS)

The biosphere and the Earth's critical zone have maintained a dynamic equilibrium for more than 3.5 billion years. Except for solar energy, almost all terrestrial substances necessary for life have been derived from near-surface portions of the land, hydrosphere, and atmosphere. If aggregate biological activities are less than the rate of nutrient supply and/or resource renewal, sustained population growth is possible. Where the replenishment rate of a life-sustaining Earth material is finite, usage may reach a condition of dynamic equilibrium in which biological consumption equals but on average cannot exceed the overall supply. Although large, most natural resources are present in finite abundances; for such commodities, excessive present-day human utilization reduces future availability, and thus the ultimate planetary carrying capacity for civilization. Intensive use of Earth materials has enhanced the quality of life, especially in the developed nations. Still, natural background levels, and Earth processes such as volcanic eruptions, as well as human activities involving agriculture, construction, and the extraction, refining, and transformation of mineral resources have led to harmful side effects involving environmental degradation and public health hazards. Among naturally and anthropogenically induced risks are bioaccessible airborne dusts and gases, soluble pollutants in agricultural, industrial, and residential waters, and toxic chemical species in foods and manufactured products. At appropriate levels of ingestion, many Earth materials are necessary for existence, but underdoses and overdoses have mild to serious consequences for human health and longevity.This overview briefly sketches several natural resource health hazards. Included are volcanic ash + aerosols + gases, mineral dusts, non-volcanic aerosols + nanoparticles, asbestos + fibrous zeolites, arsenic, fluorine, iodine, uranium + thorium + radium + radon + polonium, selenium, mercury, copper, lead, chromium, and cadmium. Also noted are health effects of natural disasters, and an obligatory future sustainable consumption of natural resources. Not treated are the overwhelming adverse effects of malnutrition, lack of potable water, inadequate sanitation, fossil fuel usage, mining, manufacturing, and agricultural pollution, or environmental pathogens, nor are the important impacts of complex mixtures of Earth materials considered.With rise of the worldwide information network, economic globalization, and the industrial thrust of Developing Nations, the achievement of natural resource sustainability has emerged as a strategic imperative. Accompanying increased rates of Earth materials consumption and attendant environmental change, substantially improved, universal public health will require a major global effort, integrating collaborations among geoscientists, medical researchers, and epidemiologists. Governments and NGOs must provide important support of such cooperative efforts, and both health and Earth scientists must cross disciplinary and national boundaries.

Ernst, W. G.

2012-10-01

96

The Frequency, Nature, and Effects of Naturally Occurring Appearance-Focused Social Comparisons  

ERIC Educational Resources Information Center

|This research examined the effects of naturally occurring appearance-focused social comparisons on women's affect, body satisfaction, and weight-related cognitions. During their daily activities, women reporting body dissatisfaction (n = 53) and women reporting body satisfaction (n = 34) recorded their reactions to comparison information.…

Leahey, Tricia M.; Crowther, Janis H.; Mickelson, Kristin D.

2007-01-01

97

Geochemistry of a naturally occurring massive marine gas hydrate  

USGS Publications Warehouse

During Deep Sea Drilling Project (DSDP) Leg 84 a core 1 m long and 6 cm in diameter of massive gas hydrate was unexpectedly recovered at Site 570 in upper slope sediment of the Middle America Trench offshore of Guatemala. This core contained only 5-7% sediment, the remainder being the solid hydrate composed of gas and water. Samples of the gas hydrate were decomposed under controlled conditions in a closed container maintained at 4??C. Gas pressure increased and asymptotically approached the equilibrium decomposition pressure for an ideal methane hydrate, CH4.5-3/4H2O, of 3930 kPa and approached to this pressure after each time gas was released, until the gas hydrate was completely decomposed. The gas evolved during hydrate decomposition was 99.4% methane, ???0.2% ethane, and ???0.4% CO2. Hydrocarbons from propane to heptane were also present, but in concentrations of less than 100 p.p.m. The carbon-isotopic composition of methane was -41 to -44 permil(( 0 00), relative to PDB standard. The observed volumetric methane/water ratio was 64 or 67, which indicates that before it was stored and analyzed, the gas hydrate probably had lost methane. The sample material used in the experiments was likely a mixture of methane hydrate and water ice. Formation of this massive gas hydrate probably involved the following processes: (i) upward migration of gas and its accumulation in a zone where conditions favored the growth of gas hydrates, (ii) continued, unusually rapid biological generation of methane, and (iii) release of gas from water solution as pressure decreased due to sea level lowering and tectonic uplift. ?? 1984.

Kvenvolden, K. A.; Claypool, G. E.; Threlkeld, C. N.; Dendy, Sloan, E.

1984-01-01

98

Suppression of ochratoxin biosynthesis by naturally occurring alkaloids.  

PubMed

The effects of four alkaloids on the biosynthesis of ochratoxin A (OTA), ochratoxin B (OTB) and citrinin were examined on four OTA-producing aspergilli: Aspergillus auricomus, A. sclerotiorum and two isolates of A. alliaceus. Piperine and piperlongumine, natural alkaloids of Piper longum, significantly inhibited OTA production at 0.001% (w/v) for all aspergilli examined. Piperine and piperlongumine affected the polyketide synthesis step of OTA production and inhibited production of citrinin. Curcumin, a constituent of tumeric, completely inhibited mycelial growth of A. alliaceus isolate 791 at 0.1% (w/v) and decreased OTA production by approximately 70% at 0.01% (w/v). Sesamin, a constituent of sesame oil, inhibited OTA and OTB production by 60 and 45%, respectively, at 0.1% (w/v), showing its effect was on chloroperoxidase and polyketide synthase activity. The potential advantage of these natural products to reduce ochratoxin contamination of agricultural commodities is discussed. PMID:17454112

Lee, S E; Park, B S; Bayman, P; Baker, J L; Choi, W S; Campbell, B C

2007-04-01

99

Interactions between plasma proteins and naturally occurring polyphenols.  

PubMed

The plant natural products known as polyphenols are found at micronutrient levels in fruits, vegetables, and plant-based beverages such as wine, tea, coffee and cocoa. Consumption of a fruit- and vegetable-rich diet, the "Mediterranean diet", has been epidemiologically related to health benefits especially for chronic diseases including diabetes, cardiovascular disease, and Alzheimer's disease. The abundance of polyphenols in plant-rich diets, and the potent bioactivities of polyphenols, provide indirect evidence for a role for polyphenols in maintaining good health. However, molecular mechanisms for therapeutic or preventative activity have not been demonstrated in vivo. We summarize the chemical classes of natural polyphenols, their bioactivities and bioavailability and metabolism. Because many polyphenols bind protein, we focus on the potential of protein binding to mediate the health-related effects of polyphenols. We discuss interactions with plasma proteins as the first target organ past the digestive tract for these orally-ingested compounds. PMID:23330924

Li, Min; Hagerman, Ann E

2013-05-01

100

Naturally Occurring Compounds Affect Glutamatergic Neurotransmission in Rat Brain  

Microsoft Academic Search

Natural products, including those derived from plants, have largely contributed to the development of therapeutic drugs. Glutamate\\u000a is the main excitatory neurotransmitter in the central nervous system and it is also considered a nociceptive neurotransmitter,\\u000a by acting on peripheral nervous system. For this reason, in this study we investigated the effects of the hydroalcooholic\\u000a extracts from Drymis winteri (polygodial and

Lucia Helena Martini; Fernanda Jung; Felix Antunes Soares; Liane Nanci Rotta; Deusa Aparecida Vendite; Marcos Emilio dos Santos Frizzo; Rosendo A. Yunes; João Batista Calixto; Susana Wofchuk; Diogo O. Souza

2007-01-01

101

Suppression of ochratoxin biosynthesis by naturally occurring alkaloids  

Microsoft Academic Search

The effects of four alkaloids on the biosynthesis of ochratoxin A (OTA), ochratoxin B (OTB) and citrinin were examined on four OTA-producing aspergilli: Aspergillus auricomus, A. sclerotiorum and two isolates of A. alliaceus. Piperine and piperlongumine, natural alkaloids of Piper longum, significantly inhibited OTA production at 0.001% (w\\/v) for all aspergilli examined. Piperine and piperlongumine affected the polyketide synthesis step

S. E. Lee; B. S. Park; P. Bayman; J. L. Baker; W. S. Choi; B. C. Campbell

2007-01-01

102

Altered Dopamine Signaling in Naturally Occurring Maternal Neglect  

Microsoft Academic Search

BackgroundChild neglect is the most common form of child maltreatment, yet the biological basis of maternal neglect is poorly understood and a rodent model is lacking.Methodology\\/Principal FindingsThe current study characterizes a population of mice (MaD1) which naturally exhibit maternal neglect (little or no care of offspring) at an average rate of 17% per generation. We identified a set of risk

Stephen C. Gammie; Michelle N. Edelmann; Caleigh Mandel-Brehm; Kimberly L. D'Anna; Anthony P. Auger; Sharon A. Stevenson; Dawn N. Albertson

2008-01-01

103

Adsorption of cobalt on some natural zeolites occurring in ?SFR  

Microsoft Academic Search

The subject of this paper was to study Co2+-ion removal from aqueous solutions by means of natural mordenite and clinoptilolite. The mentioned zeolites were of Slovak origin (SFR). The static and dynamic equilibrium adsorption of Co2+-ions by zeolites, the influence of pH, quality and quantity of interfering ions on adsorbate\\/adsorbent system were investigated. The influence of flow rate, activation and

E. Chmielewská-Horváthová; J. Lesný

1992-01-01

104

Evidence of autoinducer activity in naturally occurring biofilms  

Microsoft Academic Search

N-Acyl homoserine lactone (AHL) molecules have been shown to act as mediators of population density-dependent (quorum-sensing) gene expression in numerous Gram-negative bacteria. Functions associated with AHL include light production in Vibrio fischeri, expression of virulence factors in Pseudomonas aeruginosa, and conjugation in Agrobacterium tumefaciens. In nature, bacteria often grow as surface-adherent biofilm communities. As biofilms typically contain high concentrations of

Robert J. C McLean; Marvin Whiteley; David J Stickler; W. Claiborne Fuqua

1997-01-01

105

Naturally occurring Ngn2 promoter activators from Butea superba.  

PubMed

Neurogenin2 (Ngn2), an activator-type bHLH transcriptional factor, promotes differentiation of neural stem cells into neurons by transcription of pro-neural genes. To find neural stem cell accelerators from the extract library of natural resources, we used a two-step screening including a Ngn2 promoter reporter gene screening and differentiation assay screening of neural stem cells. A reporter gene assay that can detect Ngn2 promoter activity by luciferase expression was constructed using C3H10T1/2 cells. Using this primary cell-based screening, Butea superba was found to include Ngn2 promoter activators from our tropical plant extract libraries. Bioassay-guided fractionation of this plant extract led to the isolation of 18 natural products, including pterocarpans and isoflavonoids. Dehydromaackiain (1), formononetin (6), ()-variabilin (13), ()-medicarpin (14), rothindin (17) and ononin (18) showed 1.8–2.8 times higher Ngn2 promoter activity at 5 mM compared with control. Of active natural compounds, 30-methoxydaidzein (3) showed promotion of neurite outgrowth of C17.2 in a secondary screen. 30-Methoxydaidzein (3) increased mRNA expression of pro-neural transcriptional factors (Ngn2, Ngn1, NeuroD2), a mature neuron-specific enzyme GAD1 and a pro-neural neurotrophic growth factor neurotrophin 3 (NT3) in C17.2 neural stem cells. PMID:23903453

Arai, Midori A; Koryudzu, Kazune; Koyano, Takashi; Kowithayakorn, Thaworn; Ishibashi, Masami

2013-10-01

106

Structural characterization of naturally occurring RNA single mismatches  

PubMed Central

RNA is known to be involved in several cellular processes; however, it is only active when it is folded into its correct 3D conformation. The folding, bending and twisting of an RNA molecule is dependent upon the multitude of canonical and non-canonical secondary structure motifs. These motifs contribute to the structural complexity of RNA but also serve important integral biological functions, such as serving as recognition and binding sites for other biomolecules or small ligands. One of the most prevalent types of RNA secondary structure motifs are single mismatches, which occur when two canonical pairs are separated by a single non-canonical pair. To determine sequence–structure relationships and to identify structural patterns, we have systematically located, annotated and compared all available occurrences of the 30 most frequently occurring single mismatch-nearest neighbor sequence combinations found in experimentally determined 3D structures of RNA-containing molecules deposited into the Protein Data Bank. Hydrogen bonding, stacking and interaction of nucleotide edges for the mismatched and nearest neighbor base pairs are described and compared, allowing for the identification of several structural patterns. Such a database and comparison will allow researchers to gain insight into the structural features of unstudied sequences and to quickly look-up studied sequences.

Davis, Amber R.; Kirkpatrick, Charles C.; Znosko, Brent M.

2011-01-01

107

Measurement of isotope abundance variations in nature by gravimetric spiking isotope dilution analysis (GS-IDA).  

PubMed

Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored. PMID:23419016

Chew, Gina; Walczyk, Thomas

2013-03-19

108

Isolation and Spectral Analysis of Naturally Occurring Thiarubrine A  

NASA Astrophysics Data System (ADS)

We have designed an experiment in which students isolate and characterize thiarubrine A, a pseudo-antiaromatic 1,2-dithia-3,5-cyclohexadiene derivative. Thiarubrines are an important class of compounds which have recently received attention because of their unusual reactivity, unique biological activity, and potential medicinal applications. They possess a distinctive red color and structure features that are particularly useful for demonstrating UV-vis, NMR, and IR spectral analyses. A crude mixture containing thiarubrine A is obtained by methanol (liquid-solid) extraction of the roots of short ragweed, Ambrosia artemisiifolia. Alternatively, these compounds can be isolated from numerous taxa within the family Asteraceae. Thiarubrine A possesses alkyl, alkenyl, and alkynyl functionality, which is useful in illustrating the utility of IR and NMR in the characterization of natural products. The long wavelength UV-vis absorption band of thiarubrine is indication of the nonplanarity of dithiin ring and provides an excellent opportunity to discuss the concepts of aromaticity, conjugation, and molecular orbital theory.

Reyes, Juan; Morton, Melita; Downum, Kelsey; O'Shea, Kevin E.

2001-06-01

109

Detecting Selective Sweeps in Naturally Occurring Escherichia Coli  

PubMed Central

The nucleotide sequences of the gapA and pabB genes (separated by approximately 32.5 kb) were determined in 12 natural isolates of Escherichia coli. Three analyses were performed on the data. First, the levels of polymorphism at the loci were compared within and between E. coli and Salmonella strains relative to their degrees of constraint. Second, the gapA and pabB loci were analyzed by the Hudson-Kreitman-Aguade (HKA) test for selective neutrality. Four additional dispersed genes (crr, putP, trp and gnd) were added to the analysis to provide the necessary frame of reference. Finally, the gene genealogies of gapA and pabB were examined for topological consistency within and between the loci. These lines of evidence indicate that some evolutionary event has recently purged the variability in the region surrounding the gapA and pabB loci in E. coli. This can best be explained by the spread of a selected allele through the global E. coli population by directional selection and the resulting loss in variability in the surrounding regions due to genetic hitchhiking.

Guttman, D. S.; Dykhuizen, D. E.

1994-01-01

110

The Frequency, Nature, and Effects of Naturally Occurring Appearance-Focused Social Comparisons  

Microsoft Academic Search

This research examined the effects of naturally occurring appearance-focused social comparisons on women’s affect, body satisfaction, and weight-related cognitions. During their daily activities, women reporting body dissatisfaction (n=53) and women reporting body satisfaction (n=34) recorded their reactions to comparison information. Body-dissatisfied women engaged in more comparisons and a greater proportion of upward comparisons than body-satisfied women. Upward comparisons were associated

Tricia M. Leahey; Janis H. Crowther; Kristin D. Mickelson

2007-01-01

111

Naturally Occurring Orthopoxviruses: Potential for Recombination with Vaccine Vectors  

PubMed Central

Orthopoxviruses are being increasingly used as live recombinant vectors for vaccination against numerous infectious diseases in humans, domestic animals, and wildlife. For risk assessments and surveillance, information about the occurrence, distribution and ecology of orthopoxviruses in western Europe is important but has mainly been based on serological investigations. We have examined kidneys, lungs, spleens, and livers of Norwegian small rodents and common shrews (Sorex araneus) for the presence of orthopoxvirus DNA sequences by PCR with primers complementary to the viral thymidine kinase (TK) gene. PCR amplicons were verified as orthopoxvirus specific by hybridization with a vaccinia virus TK-specific probe. A total of 347 animals (1,388 organs) from eight locations in different parts of Norway, collected at different times of the year during 1993 to 1995, were examined. Fifty-two animals (15%) from five locations, up to 1,600 km apart, carried orthopoxvirus DNA in one or more of their organs, most frequently in the lungs. These included 9 of 68 (13%) bank voles (Clethrionomys glareolus), 4 of 13 (31%) gray-sided voles (Clethrionomys rufocanus), 3 of 11 (27%) northern red-backed voles (Clethrionomys rutilus), 16 of 76 (21%) wood mice (Apodemus sylvaticus), and 20 of 157 (13%) common shrews. The previous isolation of cowpox virus from two clinical cases of infection (human and feline) at two of the locations investigated suggests that the viruses detected are cowpox and that some of the virus-carrying small mammalian species should be included among the cowpox virus natural reservoir hosts in Scandinavia and western Europe.

Sandvik, Tore; Tryland, Morten; Hansen, Hilde; Mehl, Reidar; Moens, Ugo; Olsvik, ?rjan; Traavik, Terje

1998-01-01

112

Isotope fractionation during natural gas hydrate formation  

Microsoft Academic Search

In the task of pursuing the origin of hydrate-bound gas, isotope analysis is a well established tool of prediction. The carbon isotope values of methane, ethane, propane and i-butane will strongly indicate the source to either be microbial, thermogenic or of mixed origin. This is due to kinetic fractionation during microbial activity. In microbial CO2 reduction, the microbes tend to

Espen Nesheim Vaular; Djurdjica Corak; Tanja Barth

2010-01-01

113

Distribution of naturally occurring radionuclides (U, Th) in Timahdit black shale (Morocco).  

PubMed

Attention has been focused recently on the use of Moroccan black oil shale as the raw material for production of a new type of adsorbent and its application to U and Th removal from contaminated wastewaters. The purpose of the present work is to provide a better understanding of the composition and structure of this shale and to determine its natural content in uranium and thorium. A black shale collected from Timahdit (Morocco) was analyzed by powder X-ray diffraction and SEM techniques. It was found that calcite, dolomite, quartz and clays constitute the main composition of the inorganic matrix. Pyrite crystals are also present. A selective leaching procedure, followed by radiochemical purification and alpha-counting, was performed to assess the distribution of naturally occurring radionuclides. Leaching results indicate that 238U, 235U, 234U, 232Th, 230Th and 228Th have multiple modes of occurrence in the shale. U is interpreted to have been concentrated under anaerobic conditions. An integrated isotopic approach showed the preferential mobilization of uranium carried by humic acids to carbonate and apatite phases. Th is partitioned between silicate minerals and pyrite. PMID:17098337

Galindo, C; Mougin, L; Fakhi, S; Nourreddine, A; Lamghari, A; Hannache, H

2006-11-13

114

Stable Cl And O Isotope Ratios Of Anthropogenic And Natural Perchlorates  

NASA Astrophysics Data System (ADS)

Perchlorate (ClO4-) in aqueous systems, even in low concentrations, is recognized to have potential human health risks. The drinking and irrigation water supplies of millions of people in the U.S. have recently been found to be contaminated with perchlorate, and this problem continues to become even more widespread. Perchlorate, as a highly soluble and relatively inert anion, tends to persist over long time periods and its removal by conventional water treatment technologies is difficult and expensive. Many known sources of perchlorate contamination are anthropogenic, resulting from its extensive use as an oxidizer component in solid propellants for missiles, rockets, and fireworks. However, certain fertilizers derived from Chilean nitrate evaporate deposits are known to contain a low percentage of perchlorate (<0.5%) that may contaminate groundwater. New isotopic evidence provides insights on the possible natural sources of perchlorate in surface and ground waters. Stable isotope ratios of Cl and O can now be used to determine whether the source of perchlorates in a given area is natural or anthropogenic. Microbial perchlorate reduction has a large (˜15 per mil) kinetic isotope effect, and this may be used to identify whether natural attenuation of perchlorate is occurring. Anthropogenic perchlorate salts in milligram amounts are readily analyzed for 37Cl and 18O isotopes. Extracting an isotopically measurable amount of perchlorate from natural waters, which are usually within ppb range of concentrations, is a challenge. But with the use of a new class of highly-selective bifunctional anion exchange resins, recovery of trace amounts of perchlorate for accurate isotopic analysis has been demonstrated. Isotopic characterization is being conducted on anthropogenic perchlorate reagents, natural perchlorate-bearing salt deposits, and perchlorate-bearing groundwaters. Significant and consistent isotopic differences in both the Cl and O isotope ratios between anthropogenic and natural perchlorate sources have been identified. Anthropogenic perchlorate has ?37Cl values between -3.1 and +1.3, and ?18O values between -24.7 and -16.1. In contrast, naturally-occurring perchlorate analyzed thus far has ?37Cl values between -14.5 and -11.8, and ?18O values between -9.3 and -4.2, as well as a significant 17O excess not seen in anthropogenic perchlorate. These distinct isotopic characteristics may indicate an atmospheric origin for natural perchlorate. Perchlorate extracted from groundwater samples can be clearly identified in terms of source. Stable isotope forensics will provide a powerful tool for understanding perchlorate occurrences and contamination in the environment.

Beloso, A.; Sturchio, N. C.; Böhlke, J.; Gu, B.; Horita, J.; Brown, G.; Hatzinger, P.

2004-12-01

115

Standards for stable isotope measurements in natural compounds  

Microsoft Academic Search

RESEARCH based on stable isotope variations in natural compounds is expanding in scientific fields such as geochemistry, hydrology, environmental studies and biochemistry. However, intercomparison of results obtained in different laboratories is often not fully reliable and therefore to improve the intercalibration of deuterium and 18O measurements in natural waters, two water standards have been distributed by the International Atomic Energy

R. Gonfiantini

1978-01-01

116

Heterogeneous distribution of natural zinc isotopes in mice.  

PubMed

Zinc (Zn) is required for the function of more than 300 enzymes involved in many metabolic pathways, and is a vital micronutrient for living organisms. To investigate if Zn isotopes could be used to better understand metal homeostasis, as well as a biomarker for diseases, we assessed the distribution of natural Zn isotopes in various mouse tissues. We found that, with respect to Zn isotopes, most mouse organs are isotopically distinct and that the total range of variation within one mouse encompasses the variations observed in the Earth's crust. Therefore, biological activity may have a major impact on the distribution of Zn isotopes in inorganic materials. The most striking aspect of the data is that red blood cells and bones are enriched by ~0.5 per mil in (66)Zn relative to (64)Zn when compared to serum, and up to ~1 per mil when compared to the brain and liver. This fractionation is well explained by the equilibrium distribution of isotopes between different bonding environments of Zn in different organs. Differences in gender and genetic background did not appear to affect the isotopic distribution of Zn. Together, these results suggest the potential use of Zn isotopes as a tracer for dietary Zn, and for detecting disturbances in Zn metabolism due to pathological conditions. PMID:23589059

Moynier, Frédéric; Fujii, Toshiyuki; Shaw, Andrey S; Le Borgne, Marie

2013-06-01

117

Isotopic heterogeneity in synthetic and natural silicon carbide  

Microsoft Academic Search

The distribution of both carbon and silicon isotopes in synthetic sublimation growth SiC wafers and in natural SiC grains was studied using secondary ion mass-spectrometry (SIMS). Significant variations in both isotopic ratios were observed which were broadly correlated with the crystalline perfection as documented by Raman microspectroscopy. Domains consisting of 15R (or with its admixture) are, on average, enriched in

A. A. Shiryaev; M. Wiedenbeck; V. Reutsky; V. B. Polyakov; N. N. Mel’nik; A. A. Lebedev; R. Yakimova

2008-01-01

118

Mobilization of arsenic and other naturally occurring contaminants in groundwater of the Main Ethiopian Rift aquifers.  

PubMed

This study investigates the mechanisms of arsenic (As) and other naturally occurring contaminants (F(-), U, V, B, and Mo) mobilization from Quaternary sedimentary aquifers of the Main Ethiopian Rift (MER) and their enrichment in the local groundwater. The study is based on systematic measurements of major and trace elements as well as stable oxygen and hydrogen isotopes in groundwater, coupled with geochemical and mineralogical analyses of the aquifer rocks. The Rift Valley aquifer is composed of rhyolitic volcanics and Quaternary lacustrine sediments. X-ray fluorescence (XRF) results revealed that MER rhyolites (ash, tuff, pumice and ignimbrite) and sediments contain on average 72 wt. % and 65 wt. % SiO2, respectively. Petrographic studies of the rhyolites indicate predominance of volcanic glass, sanidine, pyroxene, Fe-oxides and plagioclase. The As content in the lacustrine sediments (mean = 6.6 mg/kg) was higher than that of the rhyolites (mean: 2.5 mg/kg). The lacustrine aquifers of the Ziway-Shala basin in the northern part of MER were identified as high As risk zones, where mean As concentration in groundwater was 22.4 ± 33.5 (range of 0.60-190 ?g/L) and 54% of samples had As above the WHO drinking water guideline value of 10 ?g/L. Field As speciation measurements showed that most of the groundwater samples contain predominantly (?80%) arsenate-As(V) over arsenite-As(III) species. The As speciation together with field data of redox potential (mean Eh = +73 ± 65 mV) and dissolved-O2 (6.6 ± 2.2 mg/L) suggest that the aquifer is predominantly oxidative. Water-rock interactions, including the dissolution of volcanic glass produces groundwater with near-neutral to alkaline pH (range 6.9-8.9), predominance of Na-HCO3 ions, and high concentration of SiO2 (mean: 85.8 ± 11.3 mg/L). The groundwater data show high positive correlation of As with Na, HCO3¯, U, B, V, and Mo (R(2) > 0.5; p < 0.001). Chemical modeling of the groundwater indicates that Fe-oxides and oxyhydroxides minerals were saturated in the groundwater, suggesting that the As reactivity is controlled by adsorption/desorption processes with these minerals. The data show that As and other oxyanion-forming elements such as U, B, Mo, and V had typically higher concentrations at pH > ?8, reflecting the pH-dependence of their mobilization. Based on the geochemical and stable isotope variations we have established a conceptual model for the occurrence of naturally occurring contaminants in MER groundwater: 1) regional groundwater recharge from the Highland, along the Rift margins, followed by lateral flow and water-rock interactions with the aquifer rocks resulted in a gradual increase of the salinity and naturally occurring contaminants towards the center of the valley; and (2) local ?(18)O-rich lake water recharge into adjacent shallow aquifers, followed by additional mobilization of As and other oxyanion-forming elements from the aquifer rocks. We posit that the combined physical-chemical conditions of the aquifers such as oxidizing state, Na-HCO3 composition, and pH>?8 lead to enhanced mobilization of oxyanion-forming elements from Fe-oxides and consequently contamination of local groundwater. These geochemical conditions characterize groundwater resources along the Eastern African Rift and thus constitute a potential threat to the quality of groundwater in larger areas of Eastern Africa. PMID:23899878

Rango, Tewodros; Vengosh, Avner; Dwyer, Gary; Bianchini, Gianluca

2013-07-11

119

Mass transfer and carbon isotope evolution in natural water systems  

USGS Publications Warehouse

This paper presents a theoretical treatment of the evolution of the carbon isotopes C13 and C14 in natural waters and in precipitates which derive from such waters. The effects of an arbitrary number of sources (such as dissolution of carbonate minerals and oxidation of organic material) and sinks (such as mineral precipitation, CO2 degassing and production of methane), and of equilibrium fractionation between solid, gas and aqueous phases are considered. The results are expressed as equations relating changes in isotopic composition to changes in conventional carbonate chemistry. One implication of the equations is that the isotopic composition of an aqueous phase may approach a limiting value whenever there are simultaneous inputs and outputs of carbonate. In order to unambiguously interpret isotopic data from carbonate precipitates and identify reactants and products in reacting natural waters, it is essential that isotopic changes are determined chiefly by reactant and product stoichiometry, independent of reaction path. We demonstrate that this is so by means of quantitative examples. The evolution equations are applied to: 1. (1) carbon-14 dating of groundwaters; 2. (2) interpretation of the isotopic composition of carbonate precipitates, carbonate cements and diagenetically altered carbonates; and 3. (3) the identification of chemical reaction stoichiometry. These applications are illustrated by examples which show the variation of ??C13 in solutions and in precipitates formed under a variety of conditions involving incongruent dissolution, CO2 degassing, methane production and mineral precipitation. ?? 1978.

Wigley, T. M. L.; Plummer, L. N.; Pearson, Jr. , F. J.

1978-01-01

120

Analyzing hillslope hydrographs using synthetic and natural isotope signature  

NASA Astrophysics Data System (ADS)

Stable isotopes of water naturally occurring in rainwater have the potential to reveal principal transport mechanisms at multiple scales - from soil profile to hillslope and catchment scale. In this contribution, we study transport processes at the hillslope scale by combining field observations of hillslope discharge and the associated oxygen-18 contents with detailed process-based numerical modeling. One-dimensional dual-continuum vertical flow and transport model (based on Richards and advection-dispersion equations) coupled with one-dimensional single-continuum lateral flow and transport model (based on diffusion wave equation for saturated subsurface flow and advection-dispersion equation for isotope transport) were used to simulate the subsurface processes during observed rainfall-runoff episodes. The observed subsurface runoff and its oxygen-18 composition were compared with the model predictions. In addition, contributions of pre-event and event water to hillslope runoff during major rainfall-runoff episodes were evaluated by means of numerical experiments involving synthetic oxygen-18 rainfall signatures. Although preferential flow played an important role in the hillslope runoff formation, pre-event water was found to be the significant runoff component in most events. Simulation results confirmed the hypothesis of substantial mixing between infiltrating rainwater and water stored in the hillslope soil profile (i.e., the oxygen-18 rainfall signatures were not transformed into the hillslope discharge signatures in a simple and intuitively predictable way). The simulated hillslope responses showed a reasonable agreement with the experimental data in terms of subsurface runoff and oxygen-18 transport dynamics. The applied modeling approach seems to describe adequately both vertical and lateral mixing of water and oxygen-18 in the hillslope segment.

Dusek, Jaromir; Vogel, Tomas; Sanda, Martin; Dohnal, Michal

2013-04-01

121

Application of the natural isotopes in researches of water resources (in Macedonia).  

National Technical Information Service (NTIS)

Isotopes techniques based on the natural stable isotopes are efficient hydrological tool for the determination of the origin of springs and other waters. Through practical example, this paper presents the application of stabile isotopes deuterium (H-2) an...

T. Anovski B. Andonovski N. Jovanovski

1996-01-01

122

Three-Month-Olds Prefer Speech to Other Naturally Occurring Signals  

Microsoft Academic Search

Human infants show a preference for listening to speech, but little is known about how infants listen to other naturally occurring sounds. Here, we test infants' listening bias for speech against a range of naturally occurring sounds that share properties of speech to varying extents and we aim to better characterize the speech properties that attract infant attention. We compared

Sarah Shultz; Athena Vouloumanos

2010-01-01

123

Mass transfer and carbon isotope evolution in natural water systems  

Microsoft Academic Search

This paper presents a theoretical treatment of the evolution of the carbon isotopes C 13 and C 14 in natural waters and in precipitates which derive from such waters. The effects of an arbitrary number of sources (such as dissolution of carbonate minerals and oxidation of organic material) and sinks (such as mineral precipitation, CO 2 degassing and production of

T. M. L. Wigley; L. N. Plummer; F. J. Pearson Jr.

1978-01-01

124

Did major changes in the stable-isotope composition of Proterozoic seawater occur?  

NASA Astrophysics Data System (ADS)

Early Proterozoic marine carbonates of the Rocknest Formation (1.93-1.89 Ga) have very depleted ?18O values (about 8‰) relative to younger, Late Proterozoic marine carbonates that formed in similar depositional environments. Two isotopic trends are superimposed on the data for open-marine components. The first involves stabilization of tidal-flat sediments during early, possibly reflux-type dolomitization by evaporative pore fluids enriched in ?18O The second trend toward isotopically light ?18O values was established during dolomitization of open-marine facies in contact either with meteoric waters (mixing zone) or under conditions of higher temperatures during burial. This resulted in precipitation of blocky, pore-occluding cements. The isotopically most enriched ooids are the best preserved normal marine components and may suggest that the ?18O of seawater was about -9.75‰ ±1.0‰ (SMOW) at 1.9 Ga. This composition would require a major change in the balance of high-temperature oxygen isotopic exchange between seawater and basalt and low-temperature weathering in order to explain the 8‰ positive shift in inferred seawater ?18O between 1.9 and 1.0 Ga. Alternatively, the depleted ?18O values represent an approximately 30-35 °C higher temperature of surface waters at 1.9 Ga. The heaviest carbonate ?13C values are +1.75permil;, more enriched than previously reported for the Early Proterozoic on the basis of bulk-rock data.

Burdett, J. W.; Grotzinger, J. P.; Arthur, M. A.

1990-03-01

125

Isotope fractionation by natural populations of sulfate-reducing bacteria  

NASA Astrophysics Data System (ADS)

Isotope fractionation during sulfate reduction was explored for natural populations of sulfate-reducing bacteria. High fractionations of 30‰ to 40‰ were produced when the natural population metabolized with indigenous organic substrate at environmental temperatures of 15°C to 25°C. Fractionations were unaffected by changes in sulfate concentration between 2 mM and 28 mM. After the natural substrate was exhausted, the sulfate-reducing bacterial population metabolized, in turn, with acetate, ethanol, and lactate. The high fractionations encountered with natural substrate were only reproduced when the amended substrate was supplied at concentrations limiting the activity of the sulfate-reducing population. Higher, nonlimiting concentrations of amended substrate produced lower fractionations of 16‰ to 21% at 25°C. The natural sulfate-reducing population, therefore, probably experienced substrate limitation while utilizing the natural substrate. At the low temperature of 5°C fractionations with amended substrate ranged from 8‰ to 14‰ and were lower than expected based on the normal relationship between rates of sulfate reduction and the extent of isotope fractionation. The processes likely acting to control the magnitude of isotope fractionation are discussed.

Canfield, D. E.

2001-04-01

126

Carbon isotopic fractionation does not occur during dark respiration in Câ and Câ plants  

Microsoft Academic Search

The magnitude of possible carbon isotopic fractionation during dark respiration was investigated with isolated mesophyll cells from mature leaves of common bean (Phaseolus vulgaris L.), a Câ plant, and corn (Zea mays L.), a C, plant. Mesophyll protoplasts were extracted from greenhouse-grown leaves and incubated in culture solutions containing different carbohydrate substrates (fructose, glucose, and sucrose) with known δ¹³C values.

Guanghui Lin; J. R. Ehleringer

1997-01-01

127

Did major changes in the stable-isotope composition of Proterozoic seawater occur  

SciTech Connect

Early Proterozoic marine carbonates of the Rocknest Formation (1.93-1.89 Ga) have very depleted {delta}{sup 18}O values (about 8{per thousand}) relative to younger, Late Proterozoic marine carbonates that formed in similar depositional environments. Two isotopic trends are superimposed on the data for open-marine components. The first involves stabilization of tidal-flat sediments during early, possibly reflux-type dolomitization by evaporative pore fluids enriched in {delta}{sup 18}O. The second trend toward isotopically light {delta}{sup 18}O values was established during dolomitization of open-marine facies in contact either with meteoric waters (mixing zone) or under conditions of higher temperatures during burial. This resulted in precipitation of blocky, pore-occluding cements. The isotopically most enriched ooids are the best preserved normal marine components and may suggest that the {delta}{sup 18}O of seawater was about {minus}9.75{per thousand} {plus minus}1.0{per thousand} (SMOW) at 1.9 Ga. This composition would require a major change in the balance of high-temperature oxygen isotopic exchange between seawater and basalt and low-temperature weathering in order to explain the 8{per thousand} positive shift in inferred seawater {delta}{sup 18}O between 1.9 and 1.0 Ga. Alternatively, the depleted {delta}{sup 18}O values represent an approximately 30-35 C higher temperature of surface waters at 1.9 Ga. The heaviest carbonate {delta}{sup 13}C values are +1.75{per thousand}, more enriched than previously reported for the Early Proterozoic on the basis of bulk-rock data.

Burdett, J.W.; Arthur, M.A. (Univ. of Rhode Island, Narragansett (USA)); Grotzinger, J.P. (Massachusetts Institute of Technology, Cambridge (USA))

1990-03-01

128

Inhibition of Gland Development in Insects by a Naturally Occurring Antiallatotropin ("Anti-Hormone")  

NSDL National Science Digital Library

The exercise will introduce the students to using chemical surgery as well as demonstrate the function of insect juvenile hormone and naturally occuring compounds in the interaction between insects and host plants.

Dorothy Feir (Saint Louis University;)

1981-06-07

129

Examination of naturally occurring polyacetylenes and alpha-terthienyl for their ability to induce cytogenetic damage.  

PubMed

alpha-Terthienyl and 5 polyacetylenes were examined for chromosome damaging activity using Syrian hamster cells. None of these naturally occurring compounds induced sister chromatid exchanges and neither alpha-terthienyl nor phenylheptatriyne induced chromosome aberrations. PMID:7418849

MacRae, W D; Chan, G F; Wat, C K; Towers, G H; Lam, J

1980-09-15

130

Study of naturally occurring, radionuclide bearing deposits at Portland Creek, Newfoundland.  

National Technical Information Service (NTIS)

A small uraniferous peat deposit located near Portland Creek, Newfoundland was investigated as part of the National Uranium Tailings Program (NUTP). The purpose of the investigation was to provide data on naturally occurring uranium series radionuclides a...

1985-01-01

131

Naturally Occurring and Iatrogenic Animal Models of Valvular, Infectious, and Arrhythmic Cardiovascular Disease  

Microsoft Academic Search

Most naturally occurring congenital cardiovascular entities found in humans have been identified in one or more species of\\u000a animals but the utility of these naturally occurring models as research subjects is not well established. Many of the congenital\\u000a diseases are associated with noncardiovascular defects and some of these may result in infertility, impotence, and other reproductive\\u000a problems that preclude the

David R. Gross

132

Naturally occurring neuronal death during the postnatal development of Purkinje cells and their precerebellar afferent projections  

Microsoft Academic Search

Naturally occurring neuronal death plays a substantial developmental role in the building of the neural circuitries. The neuronal death caused by different cerebellar mutations is mostly of an apoptotic nature. Apart from the identity of the intrinsic mechanisms of the mutations, adult cerebellar mutants are a powerful tool to causally study the development of the cerebellar connectivity. Thus, studies on

Silvia H. Madalosso; Eva M. Pérez-Villegas; José A. Armengol

2005-01-01

133

Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation  

USGS Publications Warehouse

As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

2013-01-01

134

Recent Advances in the Chemistry and Biology of Naturally Occurring Antibiotics  

PubMed Central

Lead-in Ever since the world-shaping discovery of penicillin, nature’s molecular diversity has been extensively screened for new medications and lead compounds in drug discovery. The search for anti-infective agents intended to combat infectious diseases has been of particular interest and has enjoyed a high degree of success. Indeed, the history of antibiotics is marked with impressive discoveries and drug development stories, the overwhelming majority of which have their origins in nature. Chemistry, and in particular chemical synthesis, has played a major role in bringing naturally occurring antibiotics and their derivatives to the clinic, and no doubt these disciplines will continue to be key enabling technologies for future developments in the field. In this review article, we highlight a number of recent discoveries and advances in the chemistry, biology, and medicine of naturally occurring antibiotics, with particular emphasis on the total synthesis, analog design, and biological evaluation of molecules with novel mechanisms of action.

Chen, Jason S.; Edmonds, David J.; Estrada, Anthony A.

2009-01-01

135

Isotopic identification of natural vs. anthropogenic sources of Pb in Laramie basin groundwaters, Wyoming, USA  

Microsoft Academic Search

Water well samples, precipitation, and leachates of aquifer rock samples from the Laramie basin, Wyoming, were analyzed to test the suitability of Pb isotopes for tracing hydrologic processes in a basin where Sr isotopes had proven effective. Leachable Pb from host rocks to aquifers in this basin have isotopically distinct compositions and isotopic tracing would be effective in differentiating natural

R. N. Toner; C. D. Frost; K. R. Chamberlain

2003-01-01

136

Investigating microbial carbon cycling using natural abundance isotope analysis of PLFA  

NASA Astrophysics Data System (ADS)

Understanding microbial carbon sources and cycling is fundamental to our conceptualization of microbial ecosystems and their role in biogeochemical cycling in natural systems. Achieving this understanding requires application of a wide range of approaches. Natural abundance isotope analysis of individual compounds, particularly cellular components such as Phospholipids Fatty Acids (PLFA) can provide insights into the carbon sources and metabolic activities of the in situ microbial community from environmental samples. This is primarily because specific PLFA can be well resolved by gas chromatography even from complex matrices where confounding biological/organic compound abound. These PLFA can then be attributed to the viable microbial community, in some cases to specific components of this community and due to characteristic biosynthetic fractionations of stable isotope ratios, ?13C analysis of PLFA can: differentiate isotopically distinct primary carbon sources of heterotrophic communities; identify isotopic patterns characteristic of autotrophic versus heterotrophic processes; and elucidate microbial biosynthetic pathways. In cases where there ?13C cannot provide resolution of carbon sources, new approaches in ?14C of PLFA can be applied. The vast range in ?14C of ancient and modern carbon provides an easily traceable signal that can differentiate uptake and utilization of these carbon sources. This is particularly useful in cases such as contaminated sites where petroleum based contamination has occurred, or in natural systems where microbial communities may be utilizing geologic versus recently photosynthetically fixed carbon. This talk will present several examples demonstrating the utility of this approach.

Slater, G. G.; Brady, A.; Cowie, B.

2008-12-01

137

Apoptosis and autophagy induction as mechanism of cancer prevention by naturally occurring dietary agents  

PubMed Central

Nontoxic naturally occurring compounds, especially those from dietary sources, are receiving increasing consideration for prevention and treatment of diseases including cancer. There is a growing need for innovative anticancer therapies and therefore search for natural compounds with novel biological activities or antineoplastic potential is currently an important area in drug discovery. Support for this interest also comes from increasing concern over the efficacy and safety of many conventional therapies, especially those that run over a long course of time. Laboratory studies in different in vitro and in vivo systems have shown that many natural compounds possess the capacity to regulate response to oxidative stress and DNA damage, suppress angiogenesis, inhibit cell proliferation and induce autophagy and apoptosis. This review discusses the induction of apoptosis and autophagy as a mechanism of cancer prevention by some of the most studied naturally occurring dietary compounds.

Mukhtar, Eiman; Adhami, Vaqar Mustafa; Khan, Naghma; Mukhtar, Hasan

2013-01-01

138

Characterization of a Naturally Occurring Class D ?-Lactamase from Achromobacter xylosoxidans?  

PubMed Central

A chromosomally encoded class D ?-lactamase, OXA-114, was characterized from Achromobacter xylosoxidans strain CIP69598. ?-Lactamase OXA-114 shared 56% amino acid identity with the naturally occurring class D ?-lactamase of Burkholderia cenocepacia and 42% identity with the acquired oxacillinases OXA-9 and OXA-18. OXA-114 has a narrow-spectrum hydrolysis profile, although it includes imipenem, at a very low level. PCR and sequencing revealed that blaOXA-114-like genes were identified in all A. xylosoxidans strains tested (n = 5), indicating that this ?-lactamase is naturally occurring in that species. Induction experiments with imipenem and cefoxitin did not show inducibility of blaOXA-114 expression.

Doi, Yohei; Poirel, Laurent; Paterson, David L.; Nordmann, Patrice

2008-01-01

139

Characterization of Contaminant Transport Using Naturally-Occurring U-Series Disequilibria  

SciTech Connect

Study the migration of nuclear waste contaminants in subsurface fractured systems using naturally occurring uranium and thorium-series radionuclides as tracers under in-situ physico-chemical and hydrogeologic conditions. Radioactive disequilibria among members of these decay-series nuclides can provide information on the rates of adsorption-desorption and transport of contaminants as well as on fluid transport and rock dissolution in a natural setting.

TEH-LUNG KU

2001-06-01

140

School-Age Children's Attributions About Their Own Naturally Occurring Minor Injuries: A Process Analysis  

Microsoft Academic Search

Objective: To analyze children's attribution of cause regarding their naturally occurring minor injuries in light of the pre-injury parental acceptability of children's behavior and the emotions children experienced immediately after the event. Method: Sixty-one 8-year-old children were interviewed biweekly for one year about their naturally oc- curring minor injuries. Participants monitored environmental and psychosocial elements of the injuries and later

Sara Gable; Lizette Peterson

1998-01-01

141

Neutron activation cross sections at 14.4 MeV For some naturally occurring heavy elements in the region 76 <= Z <= 82  

Microsoft Academic Search

Neutron activation cross sections at 14.4 MeV were determined for isotopes of the following naturally occurring heavy elements: Os, Pt, Au, Hg, Tl and Pb. The mixed-powder method with Ge(Li) gamma-detection was used, and the cross sections in mb are as follows. For (n, 2n) reactions (m = metastable; g = ground state); 192Os, 1993+\\/-200 (m+g); 192Pt, 2035+\\/-150 198Pt, 1009+\\/-100

A. K. Hankla; R. W. Fink; J. H. Hamilton

1972-01-01

142

Perchlorate isotope forensics with naturally produced 36Cl  

NASA Astrophysics Data System (ADS)

The source of perchlorate (ClO4-) in many surface and groundwaters is not known. Recent studies (Parker et al., 2008) suggest that natural production is widespread and common, and may involve atmospheric processes. The isotopic composition of perchlorate chlorine and oxygen has proven useful for identifying anthropogenic/natural perchlorate sources (Bohlke et al, 2005) and for exploring biodegradation in environmental samples (Sturchio et al, 2007). The stable isotope approach, however, requires processing very large volumes of water to obtain milligrams of rigorously separated perchlorate for analysis, limiting its widespread application. Chlorine-36 (36Cl) is a long-lived and rare radionuclide produced cosmogenically in the upper atmosphere. The measurement of 36Cl/Cl by accelerator mass spectrometry (AMS) only requires micrograms of sample chlorine enabling lower volume extractions (less than 1/10th that required for stable isotope techniques), and potentially less rigorous perchlorate chemistry. The primary technical goal of our work is to determine the utility of 36Cl in distinguishing perchlorate source and in constraining mechanisms of natural perchlorate formation. We expect that synthetic perchlorate compounds produced using chloride brines from ancient sources and concentrated modern deposits will have low 36Cl/Cl ratios that will be distinct from natural perchlorate produced in the atmosphere. High levels of 36Cl in groundwater or rainwater perchlorate would then be an unambiguous indication of a natural atmospheric production, and the distribution of 36Cl/Cl in precipitation and groundwater (in conjunction with stable isotope compositions) would constrain the mechanism for natural perchlorate production in the atmosphere. Using accelerator mass spectrometry (AMS), we have measured 36Cl/Cl in a number of synthetic perchlorate salts (including potassium, sodium, magnesium, and ammonium salts). Synthetic salt 36Cl/Cl atom ratios range from 1 to 35 e-15 (consistent with recently reported analyses in Sturchio et al., 2008), and are two to fifteen times the AMS background. Bohlke et al, 2005. Anal. Chem. 77, 7838-7842. Parker et al, 2008. Environ. Sci. Technol. 42, 1465-1471. Sturchio et al, 2007. Environ. Sci. Technol. 41, 2796-2802. Sturchio et al, 2008. 36Cl: Tracer of perchlorate origin? (abstr.)Goldschmidt 2008 (July 13-18, Vancouver, Canada). This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

Hillegonds, D.; Parker, D.; Singleton, M.; Buchholz, B.; Esser, B.; Moran, J.; Rood, D.; Finkel, R.

2008-12-01

143

Isotopic distributions.  

PubMed

Isotopic information determined by mass spectrometry can be used in a wide variety of applications. Broadly speaking these could be classified as "passive" applications, meaning that they use naturally occurring isotopic information, and "active" applications, meaning that the isotopic distributions are manipulated in some way. The classic passive application is the determination of chemical composition by comparing observed isotopic patterns of molecules to theoretically calculated isotopic patterns. Active applications include isotope exchange experiments of a variety of types, as well as isotope labeling in tracing studies and to provide references for quantitation. Regardless of the type of application considered, the problem of theoretical calculation of isotopic patterns almost invariably arises. This paper reviews a number of application examples and computational approaches for isotopic studies in mass spectrometry. PMID:23666722

Rockwood, Alan L; Palmblad, Magnus

2013-01-01

144

Cd Isotopic Composition Measured by Plasma Source Mass Spectrometry on Natural and Anthropogenic Materials. A Preliminary Outline of Cd Isotope Systematics  

NASA Astrophysics Data System (ADS)

Cadmium is a trace metal that is used as a geochemical tracer of natural processes, like biological productivity and paleoproductivity, and also of anthropogenic pollution, as Cd is known to be a toxic heavy metal that has become a major environmental and health concern. For these purposes, an outstanding issue is to determine whether Cd, like a number of metallic elements (e.g. Fe, Cu, Zn, Mo, Tl), may display variable isotopic compositions in natural and/or industrial compounds. It is known that Cd may display variable isotopic composition. Indeed, isotopic fractionation processes have been documented in some meteorites and in lunar soils. Consequently, due to its relatively low boiling point (767\\deg C) and also to the large mass range covered by its isotopes (10 mass units), Cd might fractionate isotopically, for example during the outpouring of acidic volcanic magmas and/or the emplacement of granitoids. On another hand, isotopic fractionation could also occur during human activities like refuse incineration or industrial manufacturing, for instance. Finally, biologically-induced isotopic fractionation should not be ruled out, as it is clearly evidenced for other metals, like Fe. A high precision method has been developed for determining the isotopic composition of Cd by plasma source mass spectrometry (Neptune). This method holds on the standard-bracketing technique, owing to the availability of Cd solutions of known isotopic composition provided by the University of M\\H{u}nster. This allows to correct precisely for mass fractionation that occurs in the plasma source mass spectrometer. It is also critical for the analysis to be possible to work with Cd solutions of very high purity. Chemical isolation of Cd involves 3 steps, and may be also suitable for Cd isotopic measurements using solid source mass spectrometry. Preliminary results suggest that Cd is likely to fractionate during smelting activities, as indicated by measurements on mining waste. The calibration of a 110Cd-116Cd double spike is underway for absolute, true isotopic ratios to be derived. The double spike technique allows the isotopic analysis of Cd using a plasma source, but also a solid source mass spectrometer, as Cd ionizes efficiently in such mass spectrometers owing to the standard silicagel technique.

Innocent, C.

2004-05-01

145

Cancer mortality in England in relation to levels of naturally occurring fluoride in water supplies  

Microsoft Academic Search

Sixty-seven small areas in England have been classified into four groups according to the level of naturally occurring fluoride in their water supplies. Small area mortality statistics for 1969-73 have been used to look for differences in cancer mortality in relation to fluoride levels. Deaths from all cancers and from cancer at 12 specific body sites have been examined; no

C Chilvers; D Conway

1985-01-01

146

Antioxidant effect of naturally occurring xanthines on the oxidative damage of DNA bases  

Microsoft Academic Search

The repair of the oxidised radicals of adenine and guanosine by several naturally occurring xanthines was studied. Each pair of DNA purine\\/xanthine was made to react with the sulphate radical and the decrease of the concentration of both compounds was measured by HPLC as a function of irradiation time. The results show that xanthine efficiently prevents the oxidation of the

A. J. S. C. Vieira; J. P. Telo; H. F. Pereira; P. F. Patrocínio; R. M. B. Dias

1999-01-01

147

Everyday Family and Community Life and Children's Naturally Occurring Learning Opportunities  

Microsoft Academic Search

National surveys of nearly 3300 parents (and other caregivers) of infants, toddlers, and preschoolers with or at-risk for developmental delays were conducted to ascertain the sources of naturally occurring learning opportunities afforded young children in the context of family and community life. One group of parents completed a survey about family life as sources of learning opportunities (N = 1723),

Carl J. Dunst; Deborah Hamby; Carol M. Trivette; Melinda Raab; Mary Beth Bruder

2000-01-01

148

Using naturally occurring tumours in dogs and cats to study telomerase and cancer stem cell biology  

Microsoft Academic Search

The recently described cancer stem cell theory opens up many new challenges and opportunities to identify targets for therapeutic intervention. However, the majority of cancer related therapeutic studies rely upon rodent models of human cancer that rarely translate into clinical success in human patients. Naturally occurring cancers in dogs, cats and humans share biological features, including molecular targets, telomerase biology

Lisa Y. Pang; David J. Argyle

2009-01-01

149

Analysis for naturally occuring radionuclides at environmental concentrations by gamma spectrometry  

Microsoft Academic Search

The analytical potential of low level, high resolution gamma-ray spectrometry for naturally occurring radionuclides at environmental levels is described, with particular emphasis on detector background levels and sensitivity. Comparisons are drawn between the performance of a specially designed low background detector system, and that of standard off the shelf devices. Sample characteristics, calibration procedures and checks, are described, and empirical

A. S. Murray; R. Marten; A. Johnston; P. Martin

1987-01-01

150

Subject Reaction to Human-Caused and Naturally-Occurring Radioactive Threat.  

ERIC Educational Resources Information Center

While research has shown that people are adversely psychologically affected by knowledge that their communities have been toxically contaminated, it has been suggested that those who see a disaster as naturally occurring tend to be less adversely affected than those who see a disaster as caused by human acts. To examine this issue, questionnaires…

Belford, Susan; Gibbs, Margaret

151

Antibacterial Activities of Naturally occurring Compounds against Mycobacterium avium subspecies paratuberculosis  

Technology Transfer Automated Retrieval System (TEKTRAN)

Antibacterial activities of 19 naturally-occurring compounds (including essential oils and some of their isolated constituents, apple and green tea polyphenols and other plant extracts) against three strains of Mycobacterium avium subspecies paratuberculosis (Map), a bovine isolate NCTC 8578, a raw ...

152

Studying Compliment Responses; A Comparison of DCTs and Recordings of Naturally Occurring talk.  

ERIC Educational Resources Information Center

Examined the differences between compliment responses collected with two different data collection procedures: naturally occurring data analyzed through conversation analytic methodology, and elicited data collected via a discourse completion task (DCT). The DCT was designed to evoke the same discourse context and preceding context observed in the…

Golato, Andrea

2003-01-01

153

Functional Characterization of Naturally Occurring Pathogenic Mutations in the Human Leptin Receptor  

Microsoft Academic Search

We have recently reported the first naturally occurring mis- sense mutations in the leptin receptor (LR) in patients with severe obesity. We have examined the molecular mechanisms by which these extracellular domain mutations disrupt LR signaling. The Ala409Glu mutant receptor is expressed at the cell surface, binds leptin normally but fails to signal to down- stream pathways. A409 is present

Wendy Kimber; Frank Peelman; Xavier Prieur; Teresia Wangensteen; Stephen O'Rahilly; Jan Tavernier; I. Sadaf Farooqi

2008-01-01

154

Changes in peripheral blood leukocyte populations in pigs with naturally occurring exudative epidermitis  

Microsoft Academic Search

The objective of the study was to analyze changes in peripheral blood leukocyte subsets in cases of naturally occurring exudative epidermitis (EE) in pigs. Five of ten piglets developed the chronic clinical form of EE 2–5 days after weaning (PW). Blood samples were obtained at 7, 14 and 21 days from both normal and clinically affected piglets for routine haematology

M. Nofrarías; J. Pujols; J. Segalés; X. Gibert; N. Majó

2006-01-01

155

Palladium-catalyzed synthesis of naturally occurring heterocyclic compounds from ortho-disubstituted aromatics  

Microsoft Academic Search

\\u000a Abstract  New reactions are described which lead to the catalytic synthesis of naturally occurring compounds or related derivatives,\\u000a such as aurones, flavones, coumarins, quinolones and indigoids. The substrates are aromatic compounds,ortho-disubstituted by groups able to interact with the catalyst, which is a palladium (0) complex.

Zhong-wei An; Marta Catellani; Gian Paolo Chiusoli

1990-01-01

156

Benford's law and naturally occurring prices in certain ebaY auctions  

Microsoft Academic Search

We show that certain winning bids for certain ebaY auctions obey Benford's Law. One implication of this is that it is unlikely that these bids are subjected to collusion among bidders, or ‘shilling’ on the part of sellers. Parenthetically, we also show that numbers from the naturally occurring Fibonacci and Lucas sequences also obey Benford's Law.

David E. Giles

2007-01-01

157

SOS induction of selected naturally occurring substances in Escherichia coli (SOS chromotest)  

Microsoft Academic Search

Naturally occurring substances were tested for genotoxicity using a modified laboratory protocol of the Escherichia coli PQ37 genotoxicity assay (SOS chromotest) in the presence and in the absence of an exogenous metabolizing system from rat liver S9-mix. Aristolochic acid I, II, the plant extract aristolochic acid and psoralene were genotoxic; cycasine, emodine, monocrotaline and retrorsine were classified as marginal genotoxic

Sebastian Kevekordes; Volker Mersch-Sundermann; Christian M Burghaus; Jan Spielberger; Heinz H Schmeiser; Volker M Arlt; Hartmut Dunkelberg

1999-01-01

158

Potent inhibitory effect of naturally occurring flavonoids quercetin and kaempferol on in vitro osteoclastic bone resorption  

Microsoft Academic Search

Several recent studies have suggested that flavonols, a class of phytochemicals with many biological activities, might exert a protective effect against post-menopausal bone loss. In the present study, we investigated the effects of quercetin and kaempferol, two of the major naturally occurring flavonols on the in vitro bone resorbing activity of osteoclasts. Our results indicate that both compounds, at concentrations

Alice Wattel; Said Kamel; Romuald Mentaverri; Florence Lorget; Christophe Prouillet; Jean-Pierre Petit; Patrice Fardelonne; Michel Brazier

2003-01-01

159

Unique single?domain antigen binding fragments derived from naturally occurring camel heavy?chain antibodies  

Microsoft Academic Search

The humoral immune response of camels, dromedaries and llamas includes functional antibodies formed by two heavy chains and no light chains. The amino acid sequence of the variable domain of the naturally occurring heavy-chain antibodies reveals the necessary adaptations to compensate for the absence of the light chain. In contrast to the conventional antibodies, a large proportion of the heavy-chain

Serge Muyldermans; Marc Lauwereys

1999-01-01

160

Therapeutic Recreation in the Naturally Occurring Retirement Community (NORC): Benefitting "Aging in Place."  

ERIC Educational Resources Information Center

|Describes how therapeutic recreation in naturally occurring retirement communities (neighborhoods where most residents are older) can promote healthy lifestyles, presenting a case report of an in-home therapeutic recreation program offered in conjunction with nursing and social services in a such a community and discussing implications for…

Kunstler, Robin

2002-01-01

161

Aging in Place in Naturally Occurring Retirement Communities: Transforming Aging Through Supportive Service Programs  

Microsoft Academic Search

The NORC Supportive Services Program (NORC-SSP) model is a community-level intervention in which older adults, building owners and managers, service providers, funders, and other community partners create a network of services and volunteer opportunities to promote aging in place among older adults who live in ‘naturally occurring retirement communities,’ housing developments and residential areas not planned for older adults but

Barbara Joyce Bedney; Robert Bruce Goldberg; Kate Josephson

2010-01-01

162

Patterns of Molecular Diversity in Naturally Occurring and Refugial Populations of the Least Chub  

Microsoft Academic Search

The least chub Iotichthys phlegethontis is a small, rare cyprinid fish endemic to the Bonneville basin, Utah. Although it was once widely distributed within the basin, naturally occurring populations are now known to exist only in four isolated geographical regions. We used nuclear (amplified fragment length polymorphism) and mitochondrial genetic markers to describe the patterns of genetic divergence and diversity

K. E. Mock; M. P. Miller

2005-01-01

163

Mechanical properties of a porcine aortic valve fixed with a naturally occurring crosslinking agent  

Microsoft Academic Search

The study investigates the mechanical properties of porcine aortic valve leaflets fixed with a naturally occurring crosslinking agent, genipin, at distinct pressure heads. Fresh and the glutaraldehyde-fixed counterparts were used as controls. Subsequent to fixation, the changes in leaflet collagen crimps and its surface morphology were investigated by light microscopy and scanning electron microscopy (SEM). Also, the crosslinking characteristics of

Hsing-Wen Sung; Yen Chang; Chi-Tung Chiu; Chiun-Nan Chen; Huang-Chien Liang

1999-01-01

164

Subject Reaction to Human-Caused and Naturally-Occurring Radioactive Threat.  

ERIC Educational Resources Information Center

|While research has shown that people are adversely psychologically affected by knowledge that their communities have been toxically contaminated, it has been suggested that those who see a disaster as naturally occurring tend to be less adversely affected than those who see a disaster as caused by human acts. To examine this issue, questionnaires…

Belford, Susan; Gibbs, Margaret

165

Analysis of Profitability of Synthetic and Naturally Occurring Pesticides in Solanecio biafrae Production  

Microsoft Academic Search

Vegetable farming offers opportunities for resource-poor farmers, because its production can be done with little capital investment. Pressure from pests reduces yields. Synthetic materials have been used to control pests, but there could be environmental problems associated with their use. Budgetary analysis was used to evaluate economics of naturally occurring and synthetic pesticides in Solanecio biafrae (Olive & Heirne) C.

A. A. Tijani; A. A. Akinola; N. A. Sofoluwe

2011-01-01

166

Comparison between five coexisting species of marine copepods feeding on naturally occurring particulate matter  

Microsoft Academic Search

Grazing by five species of copepods on naturally occurring particles has been investigated over a 1-yr period. The consumption of particles by each species was associated with changes in both total concentration and composition of suspended particulate material. All the cope- pods reacted similarly and simultaneously to the changes of the particle size spectrum by shifting their grazing pressure from

S. A. Poulet

1978-01-01

167

Cardiovascular Reactivity to a Naturally Occurring Stressor: Development and Psychometric Evaluation of a Psychophysiological Assessment Procedure  

Microsoft Academic Search

Three studies were conducted to examine the feasibility, reactive effects of assessment, stability, sampling parameters, and sensitivity of an assessment procedure designed to measure cardiovascular responses to a discrete, naturally occurring, and replicatable stressor—university course examinations. Undergraduate students monitored their blood pressure and heart rate several times during one or two classroom examinations and for several class sessions preceding each

Richard L. Hazlett; Shelley Falkin; William Lawhorn; Elizabeth Friedman; Stephen N. Haynes

1997-01-01

168

Naturally Occurring Retirement Communities: Untapped Resources to Enable Optimal Aging at Home  

Microsoft Academic Search

Staying healthy, independent and happy in one's own home is one of the greatest challenges of aging. Naturally occurring retirement communities (NORCs) are untapped and underutilized resources that have the potential to optimize health, independence, and quality of life for older individuals in an economical way. This conceptual article describes the evolution (1996–2010) of the Cherryhill NORC (13 apartment buildings;

Marita Kloseck; Richard G. Crilly; Gloria M. Gutman

2010-01-01

169

A Naturally Occurring Genetic Variant in the Human Chorionic Gonadotropin  Gene 5 Is Assembly Inefficient  

Microsoft Academic Search

The hCGb gene family is composed of six homologous genes linked in tandem repeat on chromosome 19; the order of the genes is 7, 8, 5, 1, 2, and 3. Previous studies have shown that hCGb gene 5 is highly expressed during the first trimester of pregnancy. The purpose of our study was to identify naturally occurring polymor- phisms in

AMANDA K. MILLER-LINDHOLM; ELLIOTT BEDOWS; CYNTHIA F. BARTELS; JACQUES RAMEY; VICTORIA MACLIN; RAYMOND W. RUDDON

1999-01-01

170

Cooperation between glutathione depletion and protein synthesis inhibition against naturally occurring neuronal death  

Microsoft Academic Search

It is generally agreed that naturally-occurring neuronal death in developing animals is dependent on the synthesis of proteins. Oxidative stress, as when intracellular concentrations of free radicals are raised or when cell constituents such as membrane lipids or protein thiols are oxidized, is also involved in various types of neuronal death. In the present report, we show that the number

V Castagné; P. G. H Clarke

1998-01-01

171

Nineteenth century research on naturally occurring cell death and related phenomena  

Microsoft Academic Search

Research on naturally occurring cell death is older than current opinion gives credit. More than 100 nineteenth century publications deal with it, and we review most of these. Soon after the establishment of the cell theory by Schleiden and Schwann, Carl Vogt (1842) reported cell death in the notochord and adjacent cartilage of metamorphic toads. Subsequent landmark discoveries included the

Peter G. H. Clarke; Stephanie Clarke

1996-01-01

172

The use of naturally occurring selectively isolated bacteria for inhibiting paraffin deposition  

Microsoft Academic Search

One of the most severe problems at any oil fields producing paraffinic oils is that of paraffin depositions. Romania which has a long experience in oil production is also faced with this problem in many oil fields. The microbial treatment, based on the activity of naturally occurring, selectively isolated bacteria, is already proved as an effective alternative to conventional methods

I Lazar; A Voicu; C Nicolescu; D Mucenica; S Dobrota; I. G Petrisor; M Stefanescu; L Sandulescu

1999-01-01

173

ANTIBACTERIAL ACTIVITIES OF NATURALLY OCCURRING COMPOUNDS AGAINST ANTIBIOTIC-RESISTANT MICROCOCCUS LUTEUS ATCC 10240A  

Technology Transfer Automated Retrieval System (TEKTRAN)

After demonstrating the lack of effectiveness of standard antibiotics against acquired antibiotic resistance of Micorococcus luteus (ATCC 10240A), we showed that seven naturally occurring substances were bactericidal against this bacterium, typical of strains that may be found as contaminants of foo...

174

Naturally occurring high chloride coal and superheater corrosion - a laboratory study  

Microsoft Academic Search

The fireside corrosion potential of commercial boiler tube alloys at elevated temperatures when exposed to the combustion products from a series of coals was investigated. The results of the laboratory and field tests were previously reported. In a supplementary phase of the program, the effect of chloride on similar alloys while firing a naturally occurring high chloride Midwestern bituminous coal

A. L. Plumley; W. R. Roczniak

1981-01-01

175

Naturally-Occurring Comprehension Strategies Instruction in 9th-Grade Language Arts Classrooms  

Microsoft Academic Search

In this descriptive classroom study, we used video-based observations supplemented with teacher interviews to provide precise information about the instruction of comprehension strategies that naturally occurred in 4 Norwegian lower-secondary language arts classrooms while students worked with expository texts. The results showed that the teachers varied vastly with respect to the amount of comprehension strategies instruction, that the repertoire of

Øistein Anmarkrud; Ivar Bråten

2011-01-01

176

15 N isotope biogeochemistry and natural denitrification process in groundwater: Application to the chalk aquifer of northern France  

Microsoft Academic Search

The use of 15 N natural isotope tracing in an aquifer contained within chalk rocks in northern France indicates that, under certain hydrogeological conditions, major denitrification occurs. At the boundary where the aquifer becomes confined, the nitrate concentrations decrease in the direction of groundwater flow accompanied by an exponential increase in 15 N (expressed in 15 N ) of the

André Mariotti; Alain Landreau; Béatrice Simon

1988-01-01

177

ENVIRONMENTAL ISOTOPES FOR RESOLUTION OF HYDROLOGY PROBLEMS  

EPA Science Inventory

The use of environmental isotopes as tracers in the hydrosphere is increasing as analytical instrumentation improves and more applications are discovered. There exists still misconceptions on the role of isotopes in resolving hydrology problems. Naturally occurring isotopes in th...

178

Is it necessary to raise awareness about technologically enhanced naturally occurring radioactive materials?  

PubMed

Since radiation risks are usually considered to be related to nuclear energy, the majority of research on radiation protection has focused on artificial radionuclides in radioactive wastes, spent nuclear fuel or global fallout caused by A-bomb tests and nuclear power plant failures. Far less attention has been paid to the radiation risk caused by exposure to ionizing radiation originating from natural radioactivity enhanced due to human activity, despite the fact that technologically enhanced naturally occurring radioactive materials are common in many branches of the non-nuclear industry. They differ significantly from "classical" nuclear materials and usually look like other industrial waste. The derived radiation risk is usually associated with risk caused by other pollutants and can not be controlled by applying rules designed for pure radioactive waste. Existing data have pointed out a strong need to take into account the non-nuclear industry where materials containing enhanced natural radioactivity occur as a special case of radiation risk and enclose them in the frame of the formal control. But up to now there are no reasonable and clear regulations in this matter. As a result, the non-nuclear industries of concern are not aware of problems connected with natural radioactivity or they would expect negative consequences in the case of implementing radiation protection measures. The modification of widely comprehended environmental legislation with requirements taken from radiation protection seems to be the first step to solve this problem and raise awareness about enhanced natural radioactivity for all stakeholders of concern. PMID:19809704

Michalik, Bogus?aw

2009-06-24

179

Interaction of flavonoids, the naturally occurring antioxidants with different media: A UV-visible spectroscopic study  

NASA Astrophysics Data System (ADS)

Quantitative parameters for interaction of flavonoids—the naturally occurring antioxidants, with solvents and surfactants are determined using UV-visible absorption spectroscopy. The availability of flavonoids; kaempferol, apigenin, kaempferide and rhamnetin in micelles of sodium dodecyl sulfate (SDS) is reflected in terms of partition coefficient, Kc. Thermodynamic calculations show that the process of transfer of flavonoid molecules to anionic micelles of SDS is energy efficient. A distortion in flavonoid's morphology occurs in case of kaempferol and apigenin in surfactant and water, exhibited in terms of a new band in the UV region of electronic spectra of these flavonoids. The partition coefficients of structurally related flavonoids are correlated with their antioxidant activities.

Naseem, Bushra; Shah, S. W. H.; Hasan, Aurangzeb; Sakhawat Shah, S.

2010-04-01

180

Issues in the disposal of waste containing naturally occurring radioactive material.  

PubMed

This article considers a number of key issues in the disposal of waste containing enhanced levels of naturally occurring radioactive material (NORM), including gaseous, liquid and solid media. A brief review is made of sources of natural radioactivity in the biosphere and of anthropogenic enhancement of the concentration of NORM in the various media. The factors controlling the mobility of radionuclide activity in the environment are examined and disposal options are considered, comparison also being made with disposal of nuclear fuel cycle materials, in particular the tailings of uranium mining. Current and proposed disposal practices and policies for NORM are cited, reference being made to experiences in a number of countries. PMID:9451776

Bhattacharyya, D K

1998-03-01

181

Prospective trial of metronomic chlorambucil chemotherapy in dogs with naturally occurring cancer.  

PubMed

The purpose of this study was to assess the toxicoses and antitumor activity of metronomic chlorambucil at a dosage of 4 mg m(-2) daily in dogs with naturally occurring cancer. Thirty-six dogs were enrolled in the study. The protocol was well tolerated with no grade 3 or 4 toxicoses noted. Complete remission was achieved, and lasted over 35 weeks in three dogs (mast cell tumour, soft tissue sarcoma and thyroid carcinoma). Partial remission was noted in 1 dog with histiocytic sarcoma (39 weeks duration) for an overall remission rate of 11% (4 of 36). Stable disease was noted in 17 dogs (47%) with various other cancers. The median progression-free interval was 61 days, and the median survival time was 153 days. Chlorambucil given in a metronomic protocol showed antitumor activity in dogs with a variety of naturally occurring cancers. PMID:22236329

Leach, T N; Childress, M O; Greene, S N; Mohamed, A S; Moore, G E; Schrempp, D R; Lahrman, S R; Knapp, D W

2011-09-09

182

Associations Between Cognitive Function and Naturally Occurring Daily Cortisol During Middle Adulthood: Timing Is Everything  

PubMed Central

Objectives. We examined associations between cognitive function (CF) and the naturally occurring daily cortisol levels using data from the Midlife in the United States survey and the National Study of Daily Experiences. Methods. A national sample of 1,500 (mean age = 57 years; range = 33–84, 56% female) completed a phone-based battery of cognitive tasks and 3–6 months later provided saliva samples upon waking, 30 min after waking, at lunch time, and at bedtime on 4 consecutive days. Results. Higher CF, particularly executive function, was associated with healthier daily cortisol profiles, including a steeper diurnal cortisol slope, higher morning cortisol levels, and lower afternoon and evening cortisol levels. Discussion. The results indicate that better CF is associated with healthier profiles of naturally occurring cortisol and underscore the importance of the timing of cortisol sampling.

Almeida, David M.; Lachman, Margie E.; Tun, Patricia A.; Rosnick, Christopher B.; Seeman, Teresa

2011-01-01

183

The Effect of Climate Changes on the Disposal Facility of Natural Occurring Radioactive Materials in Egypt  

Microsoft Academic Search

Oil and gas extraction and processing operations sometimes accumulate naturally occurring radioactive materials (NORM) at\\u000a concentrations above normal in by-product waste streams. There are number of industries generates NORM contaminated waste\\u000a in Egypt. Trench was used as a disposal facility for NORM contaminated waste at one site of the petroleum industry in Egypt.\\u000a \\u000a The aim of this work is to

Mohammad Mohamed; GELEEL MOHAMED

184

Pyrethroid insecticides: A naturally occurring toxin. (Latest citations from Pollution Abstracts). Published Search  

SciTech Connect

The bibliography contains citations concerning the effects of pyrethrum and pyrethroid insecticides. Topics examine toxicity to fish, worms, flies, mosquitoes, and moths. Chemical residue on crops, the transportation of pyrethrum from soils to crops, and pyrethrum accumulation in ponds and lakes are among the topics discussed. Naturally occurring and synthetic pyrethroid insecticides are included. (Contains a minimum of 173 citations and includes a subject term index and title list.)

Not Available

1993-05-01

185

Polyporus tenuiculus : a new naturally occurring mushroom that can be industrially cultivated on agricultural waste  

Microsoft Academic Search

Polyporus tenuiculus is a naturally occurring species from Central and South America that is consumed by different ethnic groups in the region.\\u000a To determine the optimal conditions for fruiting body production, two strains were assayed on wheat straw and sawdust with\\u000a or without supplements. Sixty days of incubation at 25°C were needed to produce a solid block. The highest yield

Alejandra Omarini; Bernardo E. Lechner; Edgardo Albertó

2009-01-01

186

Immunoprevention of naturally occurring endogenous murine type-C RNA viruses  

Microsoft Academic Search

GENETIC sequences coding for type-C RNA viruses exist within the DNA of mouse cells1,2. In some inbred mouse strains endogenous viruses infectious for mouse cells are spontaneously activated and replicate in the animal: there is an associated incidence of lymphoreticular neoplasia correlated with the age of onset and level of virus expression3,4. Isolates from these naturally occurring lymphoreticular neoplasms as

Meir Kende; John R. Stephenson; Gary J. Kelloff

1978-01-01

187

9-?-L(+) Adenosine: A new naturally occurring plant growth substance elicited by triacontanol in rice  

Microsoft Academic Search

The naturally occurring plant growth substance elicited by triacontanol was found to be 9-ß-L(+) adenosine by physical and spectral methods. At picomolar concentrations, 9-ß-L(+) adenosine stimulated growth as determined by dry weight measurements of several plant species. Reaction of adenosine deaminase with adenosine from rice showed that small quantities of 9-ß-L(+) adenosine exist in plants. We believe this is the

Stanley Ries; Violet Wert; N. F. D. O'Leary; Muraleedharan Nair

1990-01-01

188

Effects of naturally occurring furanocoumarins on lipid peroxidation and carbon tetrachloride induced hepatotoxicity in mice  

Microsoft Academic Search

Several naturally occurring furanocoumarins significantly inhibited microsomal lipid peroxidation not only mediated by endogeneous\\u000a iron and NADPH but also initiated by CCl4 metabolites. Phellopterin, a potent inhibitor of cytochrome P-450, exhibited an almost complete inhibition of CCl4-induced hepatotoxicity as measured by sGPT activity 24 hr after CCl4 intoxication, whereas other furanocoumarins such as imperatorin, byakangelicin and oxypeucedanin methanolate exerted no

Kuk Hyun Shin; Won Sick Woo; Ki Ho Moon; Seung Jo Yoo

1993-01-01

189

The crystal chemistry of a naturally occurring magnesium hydroxide sulfate hydrate, a precipitate of heated seawater  

Microsoft Academic Search

The crystal chemistry of a naturally occurring magnesium hydroxide sulfate hydrate, MgSO 4 · 1\\/3 Mg ( OH 2 ) · 1\\/3 H 2 O (designated MHSH(2\\/3)), and a number of existing and predicted compounds which are structurally related to MHSH(2\\/3) are discussed. An x-ray diffraction powder pattern for MHSH(2\\/3) is calculated from single crystal data to aid in the

Michael F. Hochella Jr.; Keith D. Keefer; Bernard H. W. S. Dejong

1983-01-01

190

Naturally occurring H-DNA-forming sequences are mutagenic in mammalian cells  

Microsoft Academic Search

Naturally occurring DNA sequences can form noncanonical structures such as H-DNA, which are abundant and regulate the expression of several disease-linked genes. Here, we show that H-DNA-forming sequences are intrinsically mutagenic in mammalian cells. This finding suggests that DNA is a causative factor in mutagenesis and not just the end product. By using the endogenous H-DNA-forming sequence found in the

Guliang Wang; Karen M. Vasquez

2004-01-01

191

Inhibition of Af-Nitrosodiethylamine Carcinogenesis in Mice by Naturally Occurring Organosulfur Compounds and Monoterpenes  

Microsoft Academic Search

Naturally occurring compounds belonging to two chemical groups were studied for their capacities to inhibit \\/V-nitrosodictln lamino (NI)KA)- induced carcinogenesis in female A\\/J mice. One group consists of orga- nosulfur compounds found in Alliiim species, including garlic, onions, leeks, and shallots, and the other, two monoterpenes, i.e., D-limonene and D-carvone.In an initial experiment, in which organosulfur compounds were investigated, diallyl

Lee W. Wattenberg; Velia L. Sparnins; George Barany

192

A Neighborhood Naturally Occurring Retirement Community: Views From Providers and Residents  

Microsoft Academic Search

Maximizing quality of life for older adults poses challenges for formal service providers. One strategy to identify and address factors influencing health\\/mental health and promoting autonomy of community-dwelling older people is through a Neighborhood Naturally Occurring Retirement Community (NNORC), a community development model of formal and informal home and community-based support. This article uses qualitative methods to report on critical

Laura Bronstein; Zvi D. Gellis; Bonnie L. Kenaley

2011-01-01

193

Expression of cyclooxygenase-1 and 2 in naturally-occurring canine cancer  

Microsoft Academic Search

The purpose of this work was to determine cox-1 and cox-2 expression by immunohistochemistry in forms of naturally occurring canine cancer in order to identify animal systems for pre-clinical evaluation of cox inhibitors and cox-2 inhibitors in cancer. Canine lymphoma (LSA), prostatic carcinoma (PCA), osteosarcoma (OSA), oral melanoma (MEL), oral squamous cell carcinoma (SCC), oral fibrosarcoma (FSA), mammary carcinoma (MCA),

S. I. Mohammed; K. N. M. Khan; R. S. Sellers; M. G. Hayek; D. B. DeNicola; L. Wu; P. L. Bonney; D. W. Knapp

2004-01-01

194

Glucosamine, a naturally occurring amino monosaccharide, suppresses the ADP-mediated platelet activation in humans  

Microsoft Academic Search

Objective: To evaluate the anti-thrombotic action of glucosamine, a naturally occurring amino monosaccharide, platelets were stimulated with ADP in the presence of glucosamine, and its effects on platelet functions were examined. Materials and Methods: Human platelet-rich plasma was stimulated with 2.5 ?M ADP in the presence of glucosamine (0.01 ~ 1 mM) or other aminosugars (N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine, 1 mM), and platelet

J. Hua; S. Suguro; K. Iwabuchi; Y. Tsutsumi-Ishii; K. Sakamoto; I. Nagaoka

2004-01-01

195

Naturally occurring high-chloride coal and superheater corrision laboratory study  

SciTech Connect

Commerical boiler tube alloys were tested for the corrosive effect of chloride while firing a naturally occurring high chloride Midwestern bituminous coal. On the basis of exposure in the convection pass at temperatures from 1100-1700/sup 0/F, Inconel Alloy 690 was found to have very good resistance to corrosion while Incoloy 800H and Tp-310 s. s. were good transitional materials. Poor materials were T-22, 316 s. s., Inconel 617, and Inconel 671.

Plumley, A.L.; Roczniak, W.R.

1982-10-01

196

Naturally occurring high-chloride coal and superheater corrision laboratory study  

Microsoft Academic Search

Commerical boiler tube alloys were tested for the corrosive effect of chloride while firing a naturally occurring high chloride Midwestern bituminous coal. On the basis of exposure in the convection pass at temperatures from 1100-1700°F, Inconel Alloy 690 was found to have very good resistance to corrosion while Incoloy 800H and Tp-310 s. s. were good transitional materials. Poor materials

A. L. Plumley; W. R. Roczniak

1982-01-01

197

Reducing Health Risks and Psychological Distress Among Older Black Residents of Naturally Occurring Retirement Communities  

Microsoft Academic Search

Studies indicate that living alone, or living in anonymous housing complexes-such as Naturally Occurring Retirement Communities (NORCs)-can produce feelings of isolation and loneliness, which can negatively affect psychological well-being and physical health. Little is known about how NORCs, occupied by relatively poor older minorities may provide a context for low-cost interventions directed at enhancing well-being and therefore health. Given that

Beverly P. Lyons; Carol Magai

2001-01-01

198

Characterization of a Naturally Occurring Class D  Lactamase from Achromobacter xylosoxidans  

Microsoft Academic Search

A chromosomally encoded class D -lactamase, OXA-114, was characterized from Achromobacter xylosoxi- dans strain CIP69598. -Lactamase OXA-114 shared 56% amino acid identity with the naturally occurring class D -lactamase of Burkholderia cenocepacia and 42% identity with the acquired oxacillinases OXA-9 and OXA-18. OXA-114 has a narrow-spectrum hydrolysis profile, although it includes imipenem, at a very low level. PCR and sequencing

Yohei Doi; Laurent Poirel; David L. Paterson; Patrice Nordmann

2008-01-01

199

Emissions of naturally occurring radioactivity from aluminum and copper facilities. Report No. 6 (final)  

SciTech Connect

This report summarizes five surveys which were conducted at a Bauxite mining operation, an alumina reduction plant, an aluminum reduction plant, an underground copper mine and mill, and an open pit copper mine and concentrator. Process components and controlled source releases were sampled for naturally occurring radioactivity. Particular emphasis was given to radon-222, lead-210, and polonium-210 emissions from crushing and drying processes.

Andrews, V.E.

1982-11-01

200

Soil-to-Crop Transfer Factors of Naturally Occurring Radionuclides and Stable Elements for Long-Term Dose Assessment  

SciTech Connect

A soil-to-crop transfer factor, TF, is a key parameter that directly affects the internal dose assessment for the ingestion pathway, however, obtaining TFs of various long-lived radionuclides occurred during operation of nuclear power plants is difficult because most of them could not be found in natural environments. In this study, therefore, we collected crops and their associated soils throughout Japan and measured more than 50 elements to obtain TFs under equilibrium conditions. The TFs were calculated for 42 elements (Li, Na, Mg, Al, Si, P, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Y, Mo, Cd, Sn, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tl, Pb, Th and U) from their concentrations in both crop and soil samples. The TF is defined as the concentration of an isotope in a crop (in Bq/kg or mg/kg dry weight) divided by the concentration of the isotope in soil (in Bq.kg or mg/kg dry weight). Probability distributions of TFs for 62 upland field crops were usually log-normal type so that geometric means (GMs) were calculated. The values for the elements of interest from the viewpoint of long-term dose assessment were 2.5E-02 for Se, 7.9E-02 for Sr, 3.1E-03 for Cs, 4.2E-04 for Th and 4.6E-04 for U. Leafy vegetable showed the highest TFs for all the elements among the crop groups. It was clear that these data were usually within the 95% confidence limits of TFs compiled by IAEA in Technical Report Series 364. (authors)

Uchida, S.; Tagami, K. [National Institute of Radiological Sciences, Inage-ku, Chiba (Japan)

2007-07-01

201

Comparative field water relations of three Mediterranean shrub species co-occurring at a natural CO(2) vent.  

PubMed

Annual variations in the water relations and stomatal response of Erica arborea, Myrtus communis and Juniperus communis occurring at a natural CO(2) vent were analysed under Mediterranean field conditions. A distinct gradient of CO(2)concentration ([CO(2)]) exists between two sites near a natural CO(2)-emitting vent, with higher [CO(2)] (700 micromol mol(-1)) in the proximity of the CO(2) spring. Plants at the CO(2) spring site have been growing for generations at elevated [CO(2)]. At both sites, maximum leaf conductance was related to predawn shoot water potential. The effects of water deficits during the summer drought were severe. Leaf conductance and water potential recovered after major rainfalls in September to predrought values. Strong relationships between leaf conductance, predawn water potential, and leaf-specific hydraulic resistance are consistent with the role of stomata in regulating plant water status. Considerable between-species variation in sensitivity of water potentials and stomatal characters to elevated [CO(2)] were observed. Common to all the shrubs were a reduction in leaf conductance and an increase in water potentials in response to elevated [CO(2)]. Elevated [CO(2)] decreased the sensitivity of leaf conductance to vapour pressure deficit. Morphological characters (including stomatal density and degree of sclerophylly) showed site-dependent variations, but degree and sign of such changes varied with the species and/or the season. Measurements of discrimination against (13)C provided evidence for long-term decreases of water use efficiency in CO(2) spring plants. Analysis of C isotope composition suggested that a downward adjustment of photosynthetic capacity may have occurred under elevated [CO(2)]. Elevated [CO(2)] effects on water relations and leaf morphology persisted in the long term, but the three shrubs growing in the same environment showed species-specific responses. PMID:10948241

Tognetti, R; Minnocci, A; Peñuelas, J; Raschi, A; Jones, M B

2000-06-01

202

Impaired interaction of naturally occurring mutant NF2 protein with actin-based cytoskeleton and membrane.  

PubMed

Although schwannomin, the product of the neurofibromatosis type 2 gene, shares homology with three cytoskeleton-to-membrane protein linkers defining the ERM family, the mechanism by which it exerts a tumor suppressive activity remains elusive. Based on the knowledge of naturally occurring mutations, a functional study of schwannomin was initiated. Constructs encoding the two wild-type isoforms and nine mutant forms were transfected into HeLa cells. Transiently expressed wild-type isoforms were both observed underneath the plasma membrane. At this location they were detergent insoluble and redistributed by a cytochalasin D treatment, suggesting interaction with actin-based cytoskeletal structures. Proteins with single amino acid substitutions at positions 219 and 220 demonstrated identical properties. Three different truncated schwannomins, that are prototypic for most naturally occurring NF2 mutations, were affected neither in their location nor in their cytochalasin D sensitivity. However, they were revealed to be detergent soluble, indicating a relaxed interaction with the actin-based structures. An increased solubility was also observed for a mutant with a single amino acid substitution at position 360 in the C-terminal half of the protein. Mutant proteins with either a single amino acid deletion at position 118 or an 83 amino acid deletion within the N-terminal domain had lost the submembraneous localization and tended to accumulate in perinuclear patches that were unaffected by cytochalasin D treatment. A similar behavior was observed when the N-terminal domain was entirely deleted. Taken together these observations suggest that the N-terminal domain is the main determinant that localizes the protein at the membrane where it interacts weakly with actin-based cytoskeletal structures. The C-terminal domain potentiates this interaction. With rare exceptions, most naturally occurring mutant schwannomins that have lost their tumor suppressive activity are impaired in an interaction involving actin-based structures and are no longer firmly maintained at the membrane. PMID:9425229

Deguen, B; Mérel, P; Goutebroze, L; Giovannini, M; Reggio, H; Arpin, M; Thomas, G

1998-02-01

203

Intramolecular nitrone dipolar cycloadditions: control of regioselectivity and synthesis of naturally-occurring spirocyclic alkaloids.  

PubMed

The intramolecular nitrone dipolar cycloaddition of in situ-generated nitrones such as compound 26 has been used for the synthesis of cyclic isoxazolidines 27 and 29. The regioselectivity of the intramolecular cycloaddition depends on the nature of the terminal substituent on the dipolarophile. The influence of the substituent on the regioselectivity of the cycloaddition has been examined using several model systems and two methods of nitrone formation. These studies demonstrated that the cyano-substituent plays a special role in favouring the formation of the 6,6,5-ring fused adduct 27 under thermodynamically controlled conditions. The utility of the cyclo-adduct 57 (see Scheme 12) as a precursor for the naturally occurring histrionicotoxins is illustrated by the synthesis of three "unsymmetrical" (i.e. with each side chain bearing different functional groups) members of the histrionicotoxin family HTX-259A, HTX-285C and HTX-285E (2, 3 and 4 respectively). PMID:23051904

Hodges, Alastair J; Adams, Joseph P; Bond, Andrew D; Holmes, Andrew B; Press, Neil J; Roughley, Stephen D; Ryan, John H; Saubern, Simon; Smith, Catherine J; Turnbull, Michael D; Newton, Annabella F

2012-10-11

204

Isotopic composition and neutronics of the Okelobondo natural reactor  

NASA Astrophysics Data System (ADS)

The Oklo-Okelobondo and Bangombe uranium deposits, in Gabon, Africa host Earth's only known natural nuclear fission reactors. These 2 billion year old reactors represent a unique opportunity to study used nuclear fuel over geologic periods of time. The reactors in these deposits have been studied as a means by which to constrain the source term of fission product concentrations produced during reactor operation. The source term depends on the neutronic parameters, which include reactor operation duration, neutron flux and the neutron energy spectrum. Reactor operation has been modeled using a point-source computer simulation (Oak Ridge Isotope Generation and Depletion, ORIGEN, code) for a light water reactor. Model results have been constrained using secondary ionization mass spectroscopy (SIMS) isotopic measurements of the fission products Nd and Te, as well as U in uraninite from samples collected in the Okelobondo reactor zone. Based upon the constraints on the operating conditions, the pre-reactor concentrations of Nd (150 ppm +/- 75 ppm) and Te (<1 ppm) in uraninite were estimated. Related to the burnup measured in Okelobondo samples (0.7 to 13.8 GWd/MTU), the final fission product inventories of Nd (90 to 1200 ppm) and Te (10 to 110 ppm) were calculated. By the same means, the ranges of all other fission products and actinides produced during reactor operation were calculated as a function of burnup. These results provide a source term against which the present elemental and decay abundances at the fission reactor can be compared. Furthermore, they provide new insights into the extent to which a "fossil" nuclear reactor can be characterized on the basis of its isotopic signatures. In addition, results from the study of two other natural systems related to the radionuclide and fission product transport are included. A detailed mineralogical characterization of the uranyl mineralogy at the Bangombe uranium deposit in Gabon, Africa was completed to improve geochemical models of the solubility-limiting phase. A study of the competing effects of radiation damage and annealing in a U-bearing crystal of zircon shows that low temperature annealing in actinide-bearing phases is significant in the annealing of radiation damage.

Palenik, Christopher Samuel

205

First Total Synthesis of a Naturally Occurring Iodinated 5?-Deoxyxylofuranosyl Marine Nucleoside  

PubMed Central

4-Amino-7-(5?-deoxy-?-D-xylofuranosyl)-5-iodo-pyrrolo[2,3-d]pyrimidine 1, an unusual naturally occurring marine nucleoside isolated from an ascidan, Diplosoma sp., was synthesized from D-xylose in seven steps with 28% overall yield on 10 g scale. The key step was Vorbrüggen glycosylation of 5-iodo-pyrrolo[2,3-d]pyrimidine with 5-deoxy-1,2-O-diacetyl-3-O-benzoyl-D-xylofuranose. Its absolute configuration was confirmed.

Sun, Jianyun; Dou, Yanhui; Ding, Haixin; Yang, Ruchun; Sun, Qi; Xiao, Qiang

2012-01-01

206

Quantitative assay of photoinduced antibiotic activities of naturally-occurring 2,2':5',2"-terthiophenes.  

PubMed

Nine naturally-occurring 2,2':5',2"-terthiophenes were quantitatively evaluated for their in vitro photoinduced growth inhibitory activity against three bacterial strains. All the compounds proved active towards Staphylococcus aureus. As regards Escherichia coli, the unsubstituted 2,2':5'2"-terthiophene (MIC = 0.62 microgram/ml at 4j/cm2 fluence), was found to be the only compound active. None of the compounds tested displayed activity on Pseudomonas aeruginosa at the highest concentration tested. PMID:8792675

Ciofalo, M; Petruso, S; Schillaci, D

1996-08-01

207

Naturally Occurring IgM Anti-Leukocyte Autoantibodies Inhibit T-Cell Activation and Chemotaxis  

Microsoft Academic Search

Introduction  Naturally occurring IgM antileukocyte antoantibodies (IgM-ALA) are present from birth and increase during inflammatory processes\\u000a of diverse etiologies. The clinical observation demonstrating a significant correlation (P?

Peter I. Lobo; Kailo H. Schlegal; John Vengal; Mark D. Okusa; Hong Pei

2010-01-01

208

Bibliography of reports, papers, and presentations on naturally occurring radioactive material (NORM) in petroleum industry wastes  

SciTech Connect

This bibliography was created to support projects conducted by Argonne National Laboratory (ANL) addressing issues related to naturally occurring radioactive material (NORM) in petroleum industry wastes. The bibliography provides citations for many of the available published reports, papers, articles, and presentations on petroleum industry NORM. In the past few years, the rapid expansion of NORM treatment and disposal technologies, the efforts to characterize NORM wastes and their associated potential risks, and the promulgation of state-level NORM regulatory programs have been well-documented in project reports and in papers presented at technical conferences and symposia. There are 221 citations.

Smith, K.P.; Wilkey, M.L.; Hames, R.D.

1997-07-01

209

Naturally occurring levels of elements in fishes as determined by PIXE and XRF methods  

NASA Astrophysics Data System (ADS)

Naturally occurring levels of S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Sb, Sr and Pb were measured in the gills, liver and muscles of fishes (Zosterisessor ophiocephalus Pall) in the northwestern region of the Adriatic Sea. The overall performance of PIXE and XRF methods was tested by the analysis of standard reference materials. The mean concentration values for elements were calculated from the distribution of experimentally determined concentration values. The obtained data are discussed in the framework of metal metabolism and toxicology.

Tallandini, L.; Giacobini, F.; Turchetto, M.; Galassini, S.; Liu, Q. X.; Shao, H. R.; Moschini, G.; Moro, R.; Gialanella, G.; Ghermandi, G.; Cecchi, R.; Injuk, J.; Valkovi?, V.

1989-04-01

210

Influence of Easily Degradable Naturally Occurring Carbon Substrates on Biodegradation of Monosubstituted Phenols by Aquatic Bacteria  

PubMed Central

The influence of readily degradable, naturally occurring carbon substrates on the biodegradation of several monosubstitued phenols (m-cresol, m-aminophenol, p-chlorophenol) was examined. The natural substrate classes used were amino acids, carbohydrates, and fatty acids. Samples of the microbial community from Lake Michie, a mesotrophic reservoir, were adapted to different levels of representatives from each natural substrate class in chemostats. After an extended adaptation period, the ability of the microbial community to degrade the monosubstituted phenols was determined by using a radiolabeled substrate uptake and mineralization method. Several microbiological characteristics of the communities were also measured. Adaptation to increasing concentrations of amino acids, carbohydrates, or fatty acids enhanced the ability of the microbial community to degrade all three phenols. The stimulation was largest for m-cresol and m-aminophenol. The mechanism responsible for the enhancement of monosubstituted phenol metabolism was not clearly identified, but the observation that adaptation to amino acids also increased the biodegradation of glucose and, to a lesser extent, naphthalene suggests a general stimulation of microbial metabolism. This study demonstrates that prior exposure to labile, natural substrates can significantly enhance the ability of aquatic microbial communities to respond to xenobiotics.

Shimp, Robert J.; Pfaender, Frederic K.

1985-01-01

211

Molecular- and nm-scale Investigation of the Structure and Compositional Heterogeneity of Naturally Occurring Ferrihydrite  

NASA Astrophysics Data System (ADS)

Ferrihydrite is a hydrated Fe(III) nano-oxide that forms in vast quantities in contaminated acid mine drainage environments. As a result of its high surface area, ferrihydrite is an important environmental sorbent, and plays an essential role in the geochemical cycling of pollutant metal(loid)s in these settings. Despite its environmental relevance, this nanomineral remains one of the least understood environmental solids in terms of its structure (bulk and surface), compositional variations, and the factors affecting its reactivity. Under natural aqueous conditions, ferrihydrite often precipitates in the presence of several inorganic compounds such as aluminum, silica, arsenic, etc., or in the presence of organic matter. These impurities can affect the molecular-level structure of naturally occurring ferrihydrite, thus modifying fundamental properties that are directly correlated with solid-phase stability and surface reactivity. Currently there exists a significant gap in our understanding of the structure of synthetic vs. natural ferrihydrites, due to the inherent difficulties associated to the investigation of these poorly crystalline nanophases. In this study, we combined synchrotron- and laboratory-based techniques to characterize naturally occurring ferrihydrite from an acid mine drainage system situated at the New Idria mercury mine in California. We used high-energy X-ray total scattering and pair distribution function analysis to elucidate quantitative structural details of these samples. We have additionally used scanning transmission X-ray microscopy high resolution imaging (30 nm) to evaluate the spatial relationship of major elements Si, Al, and C within ferrihydrite. Al, Si and C K-edge near- edge X-ray absorption fine structure spectroscopy and 27Al nuclear magnetic resonance spectroscopy were used to obtain short-range structural information. By combining these techniques we attain the highest level of resolution permitted by current analytical methods to study such naturally occurring nanomaterials, both at the molecular- and nm-scale. This work provides structural information at the short-, medium- and long- range, as well as evidence of compositional heterogeneity, and mineral/organic matter associations.

Cismasu, C.; Michel, F. M.; Stebbins, J. F.; Tcaciuc, A. P.; Brown, G. E.

2008-12-01

212

Oocyst Discharge, Rumen Metabolism and Performance of Early Weaned Lambs with Naturally Occurring Coccidiosis Fed Monensin  

PubMed Central

Ninety-six 9.5 kg early-weaned lambs with naturally occurring coccidiosis were fed monensin either at 0, 11, 22, or 33 mg/kg of feed for 105 days. Fecal oocyst discharge during the first three days was highest with monensin 22 mg, lowest with monensin 33 mg and averaged 149.6 × 103 oocysts per gram feces for all lambs. Monensin at 22 mg/kg of feed reduced Eimeria ninakohlyakimovae and E. ahsata oocyst discharge. Organic matter and crude protein digestibilities were highest (P ? 0.05) in lambs fed monensin 22 mg/kg of feed. Monensin increased (P ? 0.01) rumen ammonia and propionic acid and decreased (P ? 0.01) acetic acid. Feeding monensin 33 mg decreased (P ? 0.05) feed intake by 5% and had no effect on gain or feed efficiency. Optimal responses were observed with monensin at 11 mg, feed consumption was not affected, gains were 8% higher (P ? 0.05) and feed was utilized 9% more efficiently (P ? 0.05) than the controls. In conclusion, monensin was an effective therapeutic agent against naturally occurring coccidial infections in early weaned lambs. Performance responses were largest with monensin fed at the rate of 11 mg/kg of feed.

Horton, G. M. J.; Stockdale, P. H. G.

1981-01-01

213

Naturally occurring osmolytes modulate the nanomechanical properties of polycystic kidney disease domains.  

PubMed

Polycystin-1 (PC1) is a large membrane protein that is expressed along the renal tubule and exposed to a wide range of concentrations of urea. Urea is known as a common denaturing osmolyte that affects protein function by destabilizing their structure. However, it is known that the native conformation of proteins can be stabilized by protecting osmolytes that are found in the mammalian kidney. PC1 has an unusually long ectodomain with a multimodular structure including 16 Ig-like polycystic kidney disease (PKD) domains. Here, we used single-molecule force spectroscopy to study directly the effects of several naturally occurring osmolytes on the mechanical properties of PKD domains. This experimental approach more closely mimics the conditions found in vivo. We show that upon increasing the concentration of urea there is a remarkable decrease in the mechanical stability of human PKD domains. We found that protecting osmolytes such as sorbitol and trimethylamine N-oxide can counteract the denaturing effect of urea. Moreover, we found that the refolding rate of a structurally homologous archaeal PKD domain is significantly slowed down in urea, and this effect was counteracted by sorbitol. Our results demonstrate that naturally occurring osmolytes can have profound effects on the mechanical unfolding and refolding pathways of PKD domains. Based on these findings, we hypothesize that osmolytes such as urea or sorbitol may modulate PC1 mechanical properties and may lead to changes in the activation of the associated polycystin-2 channel or other intracellular events mediated by PC1. PMID:20937836

Ma, Liang; Xu, Meixiang; Oberhauser, Andres F

2010-10-11

214

Naturally Occurring Human Urinary Peptides for Use in Diagnosis of Chronic Kidney Disease*  

PubMed Central

Because of its availability, ease of collection, and correlation with physiology and pathology, urine is an attractive source for clinical proteomics/peptidomics. However, the lack of comparable data sets from large cohorts has greatly hindered the development of clinical proteomics. Here, we report the establishment of a reproducible, high resolution method for peptidome analysis of naturally occurring human urinary peptides and proteins, ranging from 800 to 17,000 Da, using samples from 3,600 individuals analyzed by capillary electrophoresis coupled to MS. All processed data were deposited in an Structured Query Language (SQL) database. This database currently contains 5,010 relevant unique urinary peptides that serve as a pool of potential classifiers for diagnosis and monitoring of various diseases. As an example, by using this source of information, we were able to define urinary peptide biomarkers for chronic kidney diseases, allowing diagnosis of these diseases with high accuracy. Application of the chronic kidney disease-specific biomarker set to an independent test cohort in the subsequent replication phase resulted in 85.5% sensitivity and 100% specificity. These results indicate the potential usefulness of capillary electrophoresis coupled to MS for clinical applications in the analysis of naturally occurring urinary peptides.

Good, David M.; Zurbig, Petra; Argiles, Angel; Bauer, Hartwig W.; Behrens, Georg; Coon, Joshua J.; Dakna, Mohammed; Decramer, Stephane; Delles, Christian; Dominiczak, Anna F.; Ehrich, Jochen H. H.; Eitner, Frank; Fliser, Danilo; Frommberger, Moritz; Ganser, Arnold; Girolami, Mark A.; Golovko, Igor; Gwinner, Wilfried; Haubitz, Marion; Herget-Rosenthal, Stefan; Jankowski, Joachim; Jahn, Holger; Jerums, George; Julian, Bruce A.; Kellmann, Markus; Kliem, Volker; Kolch, Walter; Krolewski, Andrzej S.; Luppi, Mario; Massy, Ziad; Melter, Michael; Neususs, Christian; Novak, Jan; Peter, Karlheinz; Rossing, Kasper; Rupprecht, Harald; Schanstra, Joost P.; Schiffer, Eric; Stolzenburg, Jens-Uwe; Tarnow, Lise; Theodorescu, Dan; Thongboonkerd, Visith; Vanholder, Raymond; Weissinger, Eva M.; Mischak, Harald; Schmitt-Kopplin, Philippe

2010-01-01

215

High Diversity of the Fungal Community Structure in Naturally-Occurring Ophiocordyceps sinensis  

PubMed Central

Background Ophiocordyceps sinensis (syn. Cordyceps sinensis), which is a parasite of caterpillars and is endemic to alpine regions on the Tibetan Plateau, is one of the most valuable medicinal fungi in the world. “Natural O. sinensis specimens” harbor various other fungi. Several of these other fungi that have been isolated from natural O. sinensis specimens have similar chemical components and/or pharmaceutical effects as O. sinensis. Nevertheless, the mycobiota of natural O. sinensis specimens has not been investigated in detail. Methodology/Principal Findings Based on the technique of PCR-single-strand conformation polymorphism (PCR-SSCP), the mycobiota of three different sections (stromata, sclerotia, and mycelial cortices) from natural O. sinensis specimens were investigated using both culture-dependent and -independent methods. For the culture-dependent method, 572 fungal strains were isolated, and 92 putative operational taxonomic units (OTUs) were identified from 226 sequenced strains with the threshold of 97%. For the culture-independent method, 490 fungal clones were identified from about 3000 clones of ITS fragments from the whole-community DNA; based on PCR-SSCP analyses, 266 of these clones were selected to be sequenced, and 118 putative OTUs were detected. The overwhelming majority of isolates/clones and OTUs were detected from mycelial cortices; only a few were detected from stromata and sclerotia. The most common OTUs detected with both methods belonged to Ascomycota; however, only 13 OTUs were detected simultaneously by both methods. Potential novel lineages were detected by each of the two methods. Conclusions/Significance A great number of fungal species present in the mycobiota of naturally-occurring O. sinensis specimens were detected, and many of them may represent undescribed lineages. That only a few of the same OTUs were detected by both methods indicated that different methods should be used. This study increased our understanding about the fungal community structure of this valuable medicinal herb.

Zhang, Yongjie; Zhang, Shu; Wang, Mu; Bai, Fengyan; Liu, Xingzhong

2010-01-01

216

NPACT: Naturally Occurring Plant-based Anti-cancer Compound-Activity-Target database  

PubMed Central

Plant-derived molecules have been highly valued by biomedical researchers and pharmaceutical companies for developing drugs, as they are thought to be optimized during evolution. Therefore, we have collected and compiled a central resource Naturally Occurring Plant-based Anti-cancer Compound-Activity-Target database (NPACT, http://crdd.osdd.net/raghava/npact/) that gathers the information related to experimentally validated plant-derived natural compounds exhibiting anti-cancerous activity (in vitro and in vivo), to complement the other databases. It currently contains 1574 compound entries, and each record provides information on their structure, manually curated published data on in vitro and in vivo experiments along with reference for users referral, inhibitory values (IC50/ED50/EC50/GI50), properties (physical, elemental and topological), cancer types, cell lines, protein targets, commercial suppliers and drug likeness of compounds. NPACT can easily be browsed or queried using various options, and an online similarity tool has also been made available. Further, to facilitate retrieval of existing data, each record is hyperlinked to similar databases like SuperNatural, Herbal Ingredients’ Targets, Comparative Toxicogenomics Database, PubChem and NCI-60 GI50 data.

Mangal, Manu; Sagar, Parul; Singh, Harinder; Raghava, Gajendra P. S.; Agarwal, Subhash M.

2013-01-01

217

Influence of easily degradable naturally occurring carbon substrates on biodegradation of monosubstituted phenols by aquatic bacteria  

SciTech Connect

The influence of readily degradable, naturally occurring carbon substrates on the biodegradation of several monosubstituted phenols (m-cresol, m-aminophenol, p-chlorophenol) was examined. The natural substrate classes used were amino acids, carbohydrates, and fatty acids. Samples of the microbial community from Lake Michie, a mesotrophic reservoir, were adapted to different levels of representatives from each natural substrate class in chemostats. After an extended adaptation period, the ability of the microbial community to degrade the monosubstituted phenols was determined by using a radiolabeled substrate uptake and mineralization method. Several microbiological characteristics of the communities were also measured. Adaptation to increasing concentrations of amino acids, carbohydrates, or fatty acids enhanced the ability of the microbial community to degrade all three phenols. The stimulation was largest for m-cresol and m-aminophenol. The mechanism responsible for the enhancement of monosubstituted phenol metabolism was not clearly identified, but the observation that adaptation to amino acids also increased the biodegradation of glucose and, to a lesser extend, naphthalene suggests a general stimulation of microbial metabolism.

Shimp, R.J.; Pfaender, F.K.

1985-02-01

218

NPACT: Naturally Occurring Plant-based Anti-cancer Compound-Activity-Target database.  

PubMed

Plant-derived molecules have been highly valued by biomedical researchers and pharmaceutical companies for developing drugs, as they are thought to be optimized during evolution. Therefore, we have collected and compiled a central resource Naturally Occurring Plant-based Anti-cancer Compound-Activity-Target database (NPACT, http://crdd.osdd.net/raghava/npact/) that gathers the information related to experimentally validated plant-derived natural compounds exhibiting anti-cancerous activity (in vitro and in vivo), to complement the other databases. It currently contains 1574 compound entries, and each record provides information on their structure, manually curated published data on in vitro and in vivo experiments along with reference for users referral, inhibitory values (IC(50)/ED(50)/EC(50)/GI(50)), properties (physical, elemental and topological), cancer types, cell lines, protein targets, commercial suppliers and drug likeness of compounds. NPACT can easily be browsed or queried using various options, and an online similarity tool has also been made available. Further, to facilitate retrieval of existing data, each record is hyperlinked to similar databases like SuperNatural, Herbal Ingredients' Targets, Comparative Toxicogenomics Database, PubChem and NCI-60 GI(50) data. PMID:23203877

Mangal, Manu; Sagar, Parul; Singh, Harinder; Raghava, Gajendra P S; Agarwal, Subhash M

2012-11-29

219

Background in the context of land contaminated with naturally occurring radioactive material.  

PubMed

The financial implications of choosing a particular threshold for clearance of radioactively contaminated land are substantial, particularly when one considers the volume of naturally occurring radioactive material (NORM) created each year by the production and combustion of fossil fuels and the exploitation of industrial minerals. Inevitably, a compromise needs to be reached between the level of environmental protection sought and the finite resources available for remediation. In the case of natural series radionuclides, any anthropogenic input is always superimposed on the inventory already present in the soil; this 'background' inventory is conventionally disregarded when assessing remediation targets. Unfortunately, the term is not well defined and the concept of 'background dose' is open to alternative interpretations. In this paper, we address the issue of natural background from a geochemical rather than from a solely radiological perspective, illustrating this with an example from the china clay industry. We propose a simple procedure for decision making based on activity concentrations of primordial radionuclides and their progeny. Subsequent calculations of dose need to take into account the mineralogical and chemical characteristics of the contamination, which in the case of NORM are invariably reflected in uranium series disequilibrium. PMID:23519083

Read, D; Read, G D; Thorne, M C

2013-03-21

220

Stable Isotopic and Hydrogeochemical Characteristics of Natural Attenuation in a Municipal Landfill  

NASA Astrophysics Data System (ADS)

The goal of the study is to know the mechanisms of groundwater contamination by leachate from a municipal landfill located at Busan city, Korea. This study illustrates that isotopic and major ions chemistry of groundwater and leachate is to provide redox, ion exchange and precipitation reactions occurring in the aquifer. The multivariate statistical methods were also adopted to investigate of groundwater chemistry variation induced by leachates from a landfill and to evaluate the biodegradation processes by hydrogeochemical and isotopic studies. Hydrogeochemical and stable isotope data exhibit that chemical and isotopic compositions of the landfill were significantly affected by biodegradation of organic wastes. The comparison results of hydrochemical components distribution by box-whisker plots showed that Na, Cl, and K of leachates have higher values than those of groundwaters and stream waters. It is presumably considered that the active biological activity has led to increase of temperature and bicarbonate values of leachate. The lack of correlation between bicarbonate and calcium concentrations in leachate and contaminated groundwater is ascribed to microbiologically mediated reactions. Sulfate variation of groundwaters which is induced by the difference of disseminated pyrite contents included in andesite and rhyolite implies that geology is critical parameter for the capability of natural attenuation in oxygen-limited sulfate reducing environment formed by landfill leachate. The enrichment of bicarbonate in leachates suggest that an additional source of CO2 from microbial degradation of organic wastes. The enrichment of deuterium isotopic values of leachates probably results from metanogenesis within the limited reservoir of landfill. The delta 13C-DIC values were significantly enriched in leachates than in pristine groundwater. Alkalinity showed a positive relationship with delta 13C-DIC in water samples. Some groundwater samples also showed deuterium enrichment, indicating contamination by leachate plumes. Results of this study show that landfill leachate is isotopically distinct from pristine groundwater and stream water, and suggest that stable isotopes of carbon and deuterium were used as powerful tracers to trace subsurface migration of leachate plumes and to evaluate degradation of waste organics by microbial activities.

Ko, K.; Lee, K.

2008-12-01

221

From phenotypic to molecular polymorphisms involved in naturally occurring variation of plant development.  

PubMed

An enormous amount of naturally occurring genetic variation affecting development is found within wild and domesticated plant species. This diversity is presumably involved in plant adaptation to different natural environments or in human preferences. In addition, such intraspecific variation provides the basis for the evolution of plant development at larger evolutionary scales. Natural phenotypic differences are now amenable to genetic dissection up to the identification of causal DNA polymorphisms. Here we describe 30 genes and their functional nucleotide polymorphisms currently found as underlying allelic variation accounting for plant intraspecific developmental diversity. These studies provide molecular and cellular mechanisms that determine natural variation for quantitative and qualitative traits such as: fruit and seed morphology, colour and composition; flowering time; seedling emergence; plant architecture and inflorescence or flower morphology. Besides, analyses of flowering time variation within several distant species allow molecular comparisons between species, which are detecting homologous genes with partly different functions and unrelated genes with analogous functions. Thus, considerable gene function differences are being revealed also among species. Inspection of a catalogue of intraspecific nucleotide functional polymorphisms shows that transcriptional regulators are the main class of genes involved. Furthermore, barely more than half of the polymorphisms described are located in coding regions and affect protein structure, while the rest are regulatory changes altering gene expression. These limited analyses of intraspecific developmental variation support Doebley and Lukens's proposition (1998) that modifications in cis -regulatory regions of transcriptional regulators represent a predominant mode for the evolution of novel forms, but await more detailed studies in wild plant species. PMID:16096977

Alonso-Blanco, Carlos; Mendez-Vigo, Belén; Koornneef, Maarten

2005-01-01

222

Beneficial effects of autologous bone marrow-derived mesenchymal stem cells in naturally occurring tendinopathy.  

PubMed

Tendon injuries are a common age-related degenerative condition where current treatment strategies fail to restore functionality and normal quality of life. This disease also occurs naturally in horses, with many similarities to human tendinopathy making it an ideal large animal model for human disease. Regenerative approaches are increasingly used to improve outcome involving mesenchymal stem cells (MSCs), supported by clinical data where injection of autologous bone marrow derived MSCs (BM-MSCs) suspended in marrow supernatant into injured tendons has halved the re-injury rate in racehorses. We hypothesized that stem cell therapy induces a matrix more closely resembling normal tendon than the fibrous scar tissue formed by natural repair. Twelve horses with career-ending naturally-occurring superficial digital flexor tendon injury were allocated randomly to treatment and control groups. 1X10(7) autologous BM-MSCs suspended in 2 ml of marrow supernatant were implanted into the damaged tendon of the treated group. The control group received the same volume of saline. Following a 6 month exercise programme horses were euthanized and tendons assessed for structural stiffness by non-destructive mechanical testing and for morphological and molecular composition. BM-MSC treated tendons exhibited statistically significant improvements in key parameters compared to saline-injected control tendons towards that of normal tendons and those in the contralateral limbs. Specifically, treated tendons had lower structural stiffness (p<0.05) although no significant difference in calculated modulus of elasticity, lower (improved) histological scoring of organisation (p<0.003) and crimp pattern (p<0.05), lower cellularity (p<0.007), DNA content (p<0.05), vascularity (p<0.03), water content (p<0.05), GAG content (p<0.05), and MMP-13 activity (p<0.02). Treatment with autologous MSCs in marrow supernatant therefore provides significant benefits compared to untreated tendon repair in enhancing normalisation of biomechanical, morphological, and compositional parameters. These data in natural disease, with no adverse findings, support the use of this treatment for human tendon injuries. PMID:24086616

Smith, Roger Kenneth Whealands; Werling, Natalie Jayne; Dakin, Stephanie Georgina; Alam, Rafiqul; Goodship, Allen E; Dudhia, Jayesh

2013-09-25

223

Beneficial Effects of Autologous Bone Marrow-Derived Mesenchymal Stem Cells in Naturally Occurring Tendinopathy  

PubMed Central

Tendon injuries are a common age-related degenerative condition where current treatment strategies fail to restore functionality and normal quality of life. This disease also occurs naturally in horses, with many similarities to human tendinopathy making it an ideal large animal model for human disease. Regenerative approaches are increasingly used to improve outcome involving mesenchymal stem cells (MSCs), supported by clinical data where injection of autologous bone marrow derived MSCs (BM-MSCs) suspended in marrow supernatant into injured tendons has halved the re-injury rate in racehorses. We hypothesized that stem cell therapy induces a matrix more closely resembling normal tendon than the fibrous scar tissue formed by natural repair. Twelve horses with career-ending naturally-occurring superficial digital flexor tendon injury were allocated randomly to treatment and control groups. 1X107 autologous BM-MSCs suspended in 2 ml of marrow supernatant were implanted into the damaged tendon of the treated group. The control group received the same volume of saline. Following a 6 month exercise programme horses were euthanized and tendons assessed for structural stiffness by non-destructive mechanical testing and for morphological and molecular composition. BM-MSC treated tendons exhibited statistically significant improvements in key parameters compared to saline-injected control tendons towards that of normal tendons and those in the contralateral limbs. Specifically, treated tendons had lower structural stiffness (p<0.05) although no significant difference in calculated modulus of elasticity, lower (improved) histological scoring of organisation (p<0.003) and crimp pattern (p<0.05), lower cellularity (p<0.007), DNA content (p<0.05), vascularity (p<0.03), water content (p<0.05), GAG content (p<0.05), and MMP-13 activity (p<0.02). Treatment with autologous MSCs in marrow supernatant therefore provides significant benefits compared to untreated tendon repair in enhancing normalisation of biomechanical, morphological, and compositional parameters. These data in natural disease, with no adverse findings, support the use of this treatment for human tendon injuries.

Smith, Roger Kenneth Whealands; Werling, Natalie Jayne; Dakin, Stephanie Georgina; Alam, Rafiqul; Goodship, Allen E.; Dudhia, Jayesh

2013-01-01

224

BRC dosposal alternatives for NORM (naturally-occurring radioactive materials) wastes in Texas  

SciTech Connect

The Texas Low-Level Radioactive Waste Disposal Authority has investigated low-cost, alternative disposal methods for certain wastes containing small quantities of NORM. This paper presents a multipathway safety analysis of various scenarios for disposing of wastes containing limited quantities of naturally-occurring radioactive materials (NORM) in Texas. The wastes include pipe scales and sludges from oil and gas production, residues from rare-earth mineral processing, and water treatment resins, but exclude large-volume, diffuse waste. The purpose of the safety analysis to the define concentration and quantity limits for the key nuclides of NORM what will avoid dangerous radiation exposures under different waste disposal scenarios. 2 refs., 4 figs., 1 tab.

Nielson, K.K.; Rogers, V.C. (Rogers and Associates Engineering Corp., Salt Lake City, UT (USA)); Pollard, C.S. (Texas Low-Level Radioactive Waste Disposal Authority, Austin, TX (USA))

1989-01-01

225

Using (222)Rn as a naturally occurring tracer to estimate NAPL contamination in an aquifer.  

PubMed

The naturally occurring radioisotope (222)Rn was used as a partitioning tracer to evaluate the presence and amount of a non-aqueous phase liquid (NAPL) in an aquifer. The batch experiment results of a diesel contaminated soil showed that the emanation rate of (222)Rn decreased to 31%, relative to a background rate. Batch experiment results of water contaminated by gasoline, diesel, PCE and TCE were similar. A field study to examine TCE contamination was conducted using 54 groundwater samples in Wonju city, Republic of Korea. Estimates of TCE contamination ranged from <0.001mg/L to 14.3mg/L, and (222)Rn concentrations ranged from 1.89Bq/L to 444. Results of (222)Rn analysis showed that TCE contamination was mainly restricted to an asphalt laboratory area and that the (222)Rn values of a NAPL-contaminated aquifer were correlated with TCE analytical results. PMID:23602707

Yoon, Yoon Yeol; Koh, Dong Chan; Lee, Kil Yong; Cho, Soo Young; Yang, Jae Ha; Lee, Kang Kun

2013-04-04

226

Naturally occurring Parelaphostrongylus tenuis-associated choriomeningitis in a guinea pig with neurologic signs.  

PubMed

An adult male guinea pig (Cavia porcellus) with a 1-month history of hind limb paresis, torticollis, and seizures was euthanized and submitted for necropsy. Gross examination was unremarkable, but histologic examination revealed multifocal eosinophilic and lymphoplasmacytic choriomeningitis and cross sections of nematode parasites within the leptomeninges of the midbrain and diencephalon. Morphologic features of the nematode were consistent with a metastrongyle, and the parasite was identified as Parelaphostrongylus tenuis by polymerase chain reaction testing and nucleotide sequencing. Further questioning of the owner revealed that the guinea pig was fed grass from a yard often grazed by white-tailed deer (Odocoileus virginianus). To the authors' knowledge, this is the first report of a naturally occurring P. tenuis infection in a guinea pig. PMID:23238578

Southard, T; Bender, H; Wade, S E; Grunenwald, C; Gerhold, R W

2012-12-13

227

The effect of various naturally occurring metal-binding compounds on the electrochemical behavior of aluminum  

SciTech Connect

Naturally occurring biological molecules are of considerable interest as possible corrosion inhibitors because of increased attention on the development of environmentally compatible, nonpolluting corrosion inhibitors. A hydroxamate yeast siderophore (rhodotorulic acid), a catecholate bacterial siderophore (parabactin), an adhesive protein from the blue mussel Mytilus edulis, and two metal-binding compounds isolated from the tomato and sunflower roots, namely, chlorogenic and caffeic acid, respectively, were adsorbed from solution onto pure aluminum (99.9995%) and their effect on the critical pitting potential and polarization resistance in deaerated 0.1 M NaCl was measured. These measurements were made using anodic polarization and ac impedance spectroscopy. The catechol-containing siderophore has an inhibitive effect on the critical pitting potential of aluminum in 0.1 M NaCl and increases the polarization resistance of the metal over time. The adhesive protein from the blue mussel is also effective in inhibiting the pitting of aluminum.

Hansen, D.C.; McCafferty, E. [Naval Research lab., Washington, DC (United States)

1996-01-01

228

A unique case of naturally occurring mummification of human brain tissue.  

PubMed

When skulls and bones were exhumed from a mass grave in Bulgaria and subjected to medicolegal examination they were found to originate from 39 humans aged 36-60 years old who had been buried approximately 45-50 years ago. Solid structures which strongly resembled shrunken human brain tissue were found inside 2 intact skulls. Among other bones 5 similar structures were found one of which was an almost entirely preserved human brain, and the others were fragments from different regions of the human brain. Samples of these structures were immersed in 15% aqueous glycerol solution to soften and were examined by light and electron microscopy. Samples of this material and of fresh human brain were subjected to elementary atomic spectral analysis. These complex studies indicated the samples to be naturally mummified human brain tissue and that this process had occurred due to specific conditions within the cranial cavities after burial. PMID:1419879

Radanov, S; Stoev, S; Davidov, M; Nachev, S; Stanchev, N; Kirova, E

1992-01-01

229

Naturally occurring mutations of the extracellular Ca2+-sensing receptor: implications for its structure and function.  

PubMed

The extracellular Ca2+-sensing receptor is a member of the G-protein-coupled receptor family 3 in which agonists bind to a dimeric Venus-flytrap domain in the extracellular portion of the receptor. How agonist binding to this domain leads to activation of the seven-transmembrane domain is a major unresolved question. Information derived from the three-dimensional structure of the Venus-flytrap domain of the related metabotropic glutamate type 1 receptor, and from naturally occurring mutations of the Ca2+-sensing receptor identified in subjects with familial hypocalciuric hypercalcemia and autosomal dominant hypocalcemia offers new insights into the mechanism of receptor activation, and into the mechanism of action of allosteric modulators of the receptor. PMID:12890593

Hu, Jianxin; Spiegel, Allen M

2003-08-01

230

Immunomodulatory activity of naturally occurring monoterpenes carvone, limonene, and perillic acid.  

PubMed

The immunomodulatory activity of some naturally occurring monoterpenes were studied in Balb/c mice. Administration of various monoterpenes such as carvone (100 micromoles/Kg body wt/dose/animal), limonene (100 micromoles/Kg body wt/dose/animal) and perillic acid (50 micromoles/Kg body wt/dose/animal) were found to increase the total white blood cells (WBC) count in Balb/c mice. The maximum total WBC count in carvone treated animals was observed on the 12th day (16,560 cells/cmm) while in limonene (13,783 cells/cmm) and perillic acid (14,437 cells/cmm) treated animals the maximum count was observed on the 9th day after the drug treatment. Administration of terpenoids increased the total antibody production, antibody producing cells in spleen, bone marrow cellularity and alpha-esterase positive cells significantly compared to the normal animals indicating its potentiating effect on the immune system. PMID:12784919

Raphael, T J; Kuttan, G

2003-05-01

231

Naturally occurring radioactive materials (NORM): a matter of wide societal implication.  

PubMed

Naturally occurring radioactive materials are ubiquitous on Earth and their radioactivity may become concentrated as a result of human activities. Numerous industries produce concentrated radioactivity in their by-products: the coal industry, petroleum extraction and processing, water treatment, etc. The present reference system of radiation protection does not provide a complete framework for the coherent management of all types of radioactively contaminated materials. Inconsistencies in waste management policy and practice can be noted across the board, and especially vis-à-vis the management of radioactive waste from the nuclear industry. This article reviews the present societal approach to manage materials that are radioactive but are often not recognised as being such, and place the management of radioactive materials from the nuclear industry in perspective. PMID:11302258

Pescatore, C; Menon, S

2000-12-01

232

Systems and methods for facilitating hydrogen storage using naturally occurring nanostructure assemblies  

SciTech Connect

Some or all of the needs above can be addressed by embodiments of the invention. According to embodiments of the invention, systems and methods for facilitating hydrogen storage using naturally occurring nanostructure assemblies can be implemented. In one embodiment, a method for storing hydrogen can be provided. The method can include providing diatoms comprising diatomaceous earth or diatoms from a predefined culture. In addition, the method can include heating the diatoms in a sealed environment in the presence of at least one of titanium, a transition metal, or a noble metal to provide a porous hydrogen storage medium. Furthermore, the method can include exposing the porous hydrogen storage medium to hydrogen. In addition, the method can include storing at least a portion of the hydrogen in the porous hydrogen storage medium.

Fliermans; , Carl B. (Augusta, GA)

2012-08-07

233

Naturally occurring high chloride coal and superheater corrosion - a laboratory study  

SciTech Connect

The fireside corrosion potential of commercial boiler tube alloys at elevated temperatures when exposed to the combustion products from a series of coals was investigated. The results of the laboratory and field tests were previously reported. In a supplementary phase of the program, the effect of chloride on similar alloys while firing a naturally occurring high chloride Midwestern bituminous coal in the same laboratory furnace were studied. On the basis of exposure in the convection pass at temperatures from 1100 to 1700 F, Inconel Alloy 690 was very good while Incoloy 800 and Tp-310 S.S. were good transitional materials. Poor materials were T-22, 316S.S., Inconel 617, and Inconel 671. 4 refs.

Plumley, A.L.; Roczniak, W.R.

1981-01-01

234

Naturally occurring Tyzzer's disease in cotton-top tamarins (Saguinus oedipus).  

PubMed

We noted naturally occurring infection with Clostridium piliforme (Tyzzer's disease) in 2 captive-reared cotton-top tamarins (Saguinus oedipus). Spontaneous Tyzzer's disease has been reported in multiple species of laboratory, domestic, and wild animals but is extremely rare in humans and nonhuman primates. Distinct from idiopathic colitis, which is common in cotton-top tamarins, these 2 tamarins had severe, transmural, necrotizing typhlocolitis accompanied by myocarditis and hepatitis. Abundant bacteria compatible with C. piliforme, the etiologic agent of Tyzzer's disease, were present adjacent to lesions in the cecum-colon, liver, and heart. Therefore, colitis caused by C. piliforme, although rare, should be included as a differential diagnosis in cotton-top tamarins and as a cause of postnatal mortality in this species. PMID:17348301

Sasseville, Vito G; Simon, Meredith A; Chalifoux, Laura V; Lin, Kuei-Chin; Mansfield, Keith G

2007-02-01

235

Healthy Naturally Occurring Retirement Communities: A Low-Cost Approach to Facilitating Healthy Aging  

PubMed Central

Naturally occurring retirement communities (NORCs) are broadly defined as communities where individuals either remain or move when they retire. Using the determinants of health model as a base, we hypothesize that some environmental determinants have a different impact on people at different ages. Health benefits to living within NORCs have been observed and likely vary depending upon where the specific NORC exists on the NORC to healthy-NORC spectrum. Some NORC environments are healthier than others for seniors, because the NORC environment has characteristics associated with better health for seniors. Health benefits within healthy NORCs are higher where physical and social environments facilitate greater activity and promote feelings of well-being. Compared to the provision of additional medical or social services, healthy NORCs are a low-cost community-level approach to facilitating healthy aging. Municipal governments should pursue policies that stimulate and support the development of healthy NORCs.

Masotti, Paul J.; Fick, Robert; Johnson-Masotti, Ana; MacLeod, Stuart

2006-01-01

236

Characterization of Naturally-Occurring Humoral Immunity to AAV in Sheep  

PubMed Central

AAV vectors have shown great promise for clinical gene therapy (GT), but pre-existing human immunity against the AAV capsid often limits transduction. Thus, testing promising AAV-based GT approaches in an animal model with similar pre-existing immunity could better predict clinical outcome. Sheep have long been used for basic biological and preclinical studies. Moreover, we have re-established a line of sheep with severe hemophilia A (HA). Given the impetus to use AAV-based GT to treat hemophilia, we characterized the pre-existing ovine humoral immunity to AAV. ELISA revealed naturally-occurring antibodies to AAV1, AAV2, AAV5, AAV6, AAV8, and AAV9. For AAV2, AAV8, and AAV9 these inhibit transduction in a luciferase-based neutralization assay. Epitope mapping identified peptides that were common to the capsids of all AAV serotypes tested (AAV2, AAV5, AAV8 and AAV9), with each animal harboring antibodies to unique and common capsid epitopes. Mapping using X-ray crystallographic AAV capsid structures demonstrated that these antibodies recognized both surface epitopes and epitopes located within regions of the capsid that are internal or buried in the capsid structure. These results suggest that sheep harbor endogenous AAV, which induces immunity to both intact capsid and to capsid epitopes presented following proteolysis during the course of infection. In conclusion, their clinically relevant physiology and the presence of naturally-occurring antibodies to multiple AAV serotypes collectively make sheep a unique model in which to study GT for HA, and other diseases, and develop strategies to circumvent the clinically important barrier of pre-existing AAV immunity.

Tellez, Joseph; Van Vliet, Kim; Tseng, Yu-Shan; Finn, Jonathan D.; Tschernia, Nick; Almeida-Porada, Graca; Arruda, Valder R.; Agbandje-McKenna, Mavis; Porada, Christopher D.

2013-01-01

237

Characterization of Naturally-Occurring Humoral Immunity to AAV in Sheep.  

PubMed

AAV vectors have shown great promise for clinical gene therapy (GT), but pre-existing human immunity against the AAV capsid often limits transduction. Thus, testing promising AAV-based GT approaches in an animal model with similar pre-existing immunity could better predict clinical outcome. Sheep have long been used for basic biological and preclinical studies. Moreover, we have re-established a line of sheep with severe hemophilia A (HA). Given the impetus to use AAV-based GT to treat hemophilia, we characterized the pre-existing ovine humoral immunity to AAV. ELISA revealed naturally-occurring antibodies to AAV1, AAV2, AAV5, AAV6, AAV8, and AAV9. For AAV2, AAV8, and AAV9 these inhibit transduction in a luciferase-based neutralization assay. Epitope mapping identified peptides that were common to the capsids of all AAV serotypes tested (AAV2, AAV5, AAV8 and AAV9), with each animal harboring antibodies to unique and common capsid epitopes. Mapping using X-ray crystallographic AAV capsid structures demonstrated that these antibodies recognized both surface epitopes and epitopes located within regions of the capsid that are internal or buried in the capsid structure. These results suggest that sheep harbor endogenous AAV, which induces immunity to both intact capsid and to capsid epitopes presented following proteolysis during the course of infection. In conclusion, their clinically relevant physiology and the presence of naturally-occurring antibodies to multiple AAV serotypes collectively make sheep a unique model in which to study GT for HA, and other diseases, and develop strategies to circumvent the clinically important barrier of pre-existing AAV immunity. PMID:24086458

Tellez, Joseph; Van Vliet, Kim; Tseng, Yu-Shan; Finn, Jonathan D; Tschernia, Nick; Almeida-Porada, Graça; Arruda, Valder R; Agbandje-McKenna, Mavis; Porada, Christopher D

2013-09-24

238

Nineteenth century research on naturally occurring cell death and related phenomena.  

PubMed

Research on naturally occurring cell death is older than current opinion gives credit. More than 100 nineteenth century publications deal with it, and we review most of these. Soon after the establishment of the cell theory by Schleiden and Schwann, Carl Vogt (1842) reported cell death in the notochord and adjacent cartilage of metamorphic toads. Subsequent landmark discoveries included the massive cell death that occurs in pupating diptera (Weismann 1864), chondrocyte death during endochondral ossification (Stieda 1872), phagocytosis associated with cell death in the muscles of metamorphic toads (Metschnikoff 1883), chromatolytic (apoptotic) cell death in ovarian follicles (Flemming 1885), the reinterpretation of "Sarkoplasten" as "Sarkolyten" in metamorphic amphibia (Mayer 1886), the programmed loss of an entire population of neurons in fish embryos (Beard 1889), the death of scattered myocytes and myofibres in mammalian muscle (Felix 1889), and the death of many motor and sensory neurons in chick embryos (Collin 1906). Other lines of nineteenth century research established concepts important for understanding cell death, notably trophic interactions between neurons and their targets, and intercellular competition. PMID:8742050

Clarke, P G; Clarke, S

1996-02-01

239

Naturally occurring neuronal plasticity in visual wulst of the Baya weaver, Ploceus philippinus (Linnaeus, 1766).  

PubMed

The visual wulst (VW), the rostro-dorsal surface of the avian telencephalon extending from the midline to the lateral region of the brain, is a laminated "bulge" consisting in four histologically distinct rostro-caudally arranged laminae with a specific sequence: hyperpallium apicale, interstitial nucleus of hyperpallium apicale, hyperpallium intercalatum and hyperpallium densocellulare. The VW has been proposed to be the avian equivalent of the mammalian striate cortex. Various behavioral studies including lesion experiments have indicated the importance of the VW, which receives visual and/or auditory cues. We have investigated qualitatively and quantitatively the fascinating structural changes occurring in VW neurons of the seasonally breeding bird, Ploceus philippinus (Linnaeus, 1766). The Golgi method was used to study the seasonal fluctuations in the neuronal classes of the VW with regard to dendritic thickness, spine morphology and spine density during both the non-breeding and breeding periods of male Baya weaver birds. Significant variations in parameters studied among the various neuronal types located in the different well-demarcated regions of the VW are believed to contribute to the functional differences reported among the wulst regions. Thus, this study extends our view demonstrating naturally occurring neuronal plasticity in a seasonally dynamic avian brain of a bird that hones not only its learning and memorizing system but also its social and sexual system in preparation for the breeding season. PMID:23435992

Srivastava, U C; Gaur, Parul

2013-02-26

240

P-Element repression in Drosophila melanogaster by a naturally occurring defective telomeric P copy.  

PubMed Central

In Drosophila melanogaster, hybrid dysgenesis occurs in progeny from crosses between females lacking P elements and males carrying P elements scattered throughout the genome. We have genetically isolated a naturally occurring P insertion at cytological location 1A, from a Tunisian population. The Nasr'Allah-P(1A) element [NA-P(1A)] has a deletion of the first 871 bp including the P promoter. It is flanked at the 3' end by telomeric associated sequences and at the 5' end by a HeT-A element sequence. The NA-P(1A) element strongly represses dysgenic sterility and P transposition. However, when testing P-promoter repression, NA-P(1A) was unable to repress a germinally expressed P-lacZ construct bearing no 5'-homology with it. Conversely, a second P-lacZ construct, in which the fusion with lacZ takes place in exon 3 of P, was successfully repressed by NA-P(1A). This suggests that NA-P(1A) repression involves a homology-dependent component.

Marin, L; Lehmann, M; Nouaud, D; Izaabel, H; Anxolabehere, D; Ronsseray, S

2000-01-01

241

Phosphate removal from wastewaters by a naturally occurring, calcium-rich sepiolite.  

PubMed

Developing an easily handled and cost-effective phosphate absorbent is crucial for the control of water eutrophication. In this study, a naturally occurring, calcium-rich sepiolite (NOCS) was evaluated for its feasibility as a phosphate absorbent candidate. Batch studies showed that phosphate sorption on NOCS followed a stepwise isotherm for concentrations between 5 and 1000 mg P/l, and the phosphate sorption was fitted well by the Freundlich equation. The estimated maximum phosphorus sorption capacity was 32.0 mg P/g, which was quite high compared with other natural materials and was comparable to some efficient manmade P absorbents. The NOCS sorption kinetics followed a pseudo-first-order model with an R(2) value of 0.999. The adsorption of phosphate was highly pH dependent. Phosphate adsorption decreased moderately with increasing pH values from 3.0 to 6.0, and it decreased sharply in alkaline conditions. Ionic strength, sulfate, nitrate and chloride anions had no effects on the phosphate removal capacity of NOCS, but fluoride and bicarbonate anions exerted large effects. Phosphorus fractionation indicated that phosphate removed from the solution was primarily formed as a calcium-bound phosphorus precipitation, which was further confirmed by SEM-EDS analysis. Moreover, phosphate was barely (<1.5%) desorbed from the phosphorus-adsorbed sepiolite regardless of pH value. PMID:22088501

Yin, Hongbin; Yun, Ye; Zhang, Yinlong; Fan, Chengxin

2011-10-29

242

Acoustic surface perception from naturally occurring step sounds of a dexterous hexapod robot  

NASA Astrophysics Data System (ADS)

Legged robots that exhibit dynamic dexterity naturally interact with the surface to generate complex acoustic signals carrying rich information on the surface as well as the robot platform itself. However, the nature of a legged robot, which is a complex, hybrid dynamic system, renders the more common approach of model-based system identification impractical. The present paper focuses on acoustic surface identification and proposes a non-model-based analysis and classification approach adopted from the speech processing literature. A novel feature set composed of spectral band energies augmented by their vector time derivatives and time-domain averaged zero crossing rate is proposed. Using a multi-dimensional vector classifier, these features carry enough information to accurately classify a range of commonly occurring indoor and outdoor surfaces without using of any mechanical system model. A comparative experimental study is carried out and classification performance and computational complexity are characterized. Different feature combinations, classifiers and changes in critical design parameters are investigated. A realistic and representative acoustic data set is collected with the robot moving at different speeds on a number of surfaces. The study demonstrates promising performance of this non-model-based approach, even in an acoustically uncontrolled environment. The approach also has good chance of performing in real-time.

Cuneyitoglu Ozkul, Mine; Saranli, Afsar; Yazicioglu, Yigit

2013-10-01

243

Controls on chemistry and diagenesis of naturally occurring iron-oxide phases  

SciTech Connect

The purposes of this study were to (i) document chemical and mineralogical compositions in two naturally acidic drainages over a 1 m soil profile, (ii) document organic and inorganic signatures representative of past chemical or biological processes in the soils, and (iii) determine whether mineralogical and chemical differences are a consequence of differences in original composition, depositional conditions, or diagenesis. Two sites were studied: Paymaster Creek in the Heddleston Mining District near Lincoln, Montana and the New World Mining District near Cooke City, Montana. The oldest deposits at both naturally acidic sites pre-date human mining activity by several thousand years, although there is recent human activity at both sites. Both sites have streams with high dissolved Fe and moderately low pH and actively accumulate schwertmannite on streambeds. Soil deposits away from the streambed at Paymaster Creek contained goethite with adsorbed sulfate, but no schwertmannite, suggesting either that the original conditions precluded schwertmannite precipitation or that diagenesis occurred rapidly converting the schwertmannite to goethite. The New World Mining District site showed the expected profile, which is a gradual transition from schwertmannite- and goethite-bearing soils to goethite-only soils. Concentrations of Cr, As and other trace elements shown to retard diagenesis were higher at the New World site than at the Paymaster site.

Nancy W. Hinman; J. Michelle Kotler; Beizhan Yan; Aaron Tenesch; Richard V. Morris; Daphne L. Stoner; Jill R. Scott

2009-07-01

244

Characterization of a naturally occurring recombinant isolate of Grapevine fanleaf virus.  

PubMed

The naturally occurring Grapevine fanleaf virus (GFLV) recombinant isolate A17b was recovered from its grapevine host by sap inoculation and serial passages onto Gomphrena globosa, a pseudo local lesion herbaceous host, and Chenopodium quinoa, a systemic herbaceous host, to characterize some of its biological properties. Sequence analysis of the CP gene, in which a recombinational event was previously detected, demonstrated the genetic stability of recombinant isolate A17b over a 5-year period in its natural host as well as in C. quinoa. Also, recombinant isolate A17b was graft transmissible, as shown by an in vitro heterologous approach, and transmitted by the nematode Xiphinema index as readily as nonrecombinant GFLV isolates. Furthermore, despite a lower pathogenicity on Chenopodium amaranticolor, recombinant isolate A17b had a similar host range and induced similar symptoms in type and severity to nonrecombinant GFLV isolates. Interestingly, the use of infectious chimeric RNA2 transcripts in combination to RNA1 transcripts of GFLV strain F13 suggested no implication of the recombination event in the CP gene of isolate A17b in the reduced pathogenicity on C. amaranticolor. Altogether, recombinant isolate A17b had similar biological properties to GFLV nonrecombinant isolates. PMID:15968475

Vigne, E; Demangeat, G; Komar, V; Fuchs, M

2005-06-22

245

Effects of naturally occurring coumarins on hepatic drug-metabolizing enzymes inmice  

SciTech Connect

Cytochromes P450 (P450s) and glutathione S-transferases (GSTs) constitute two important enzyme families involved in carcinogen metabolism. Generally, P450s play activation or detoxifying roles while GSTs act primarily as detoxifying enzymes. We previously demonstrated that oral administration of the linear furanocoumarins, isopimpinellin and imperatorin, modulated P450 and GST activities in various tissues of mice. The purpose of the present study was to compare a broader range of naturally occurring coumarins (simple coumarins, and furanocoumarins of the linear and angular type) for their abilities to modulate hepatic drug-metabolizing enzymes when administered orally to mice. We now report that all of the different coumarins tested (coumarin, limettin, auraptene, angelicin, bergamottin, imperatorin and isopimpinellin) induced hepatic GST activities, whereas the linear furanocoumarins possessed the greatest abilities to induce hepatic P450 activities, in particular P450 2B and 3A. In both cases, this corresponded to an increase in protein expression of the enzymes. Induction of P4502B10, 3A11, and 2C9 by xenobiotics often is a result of activation of the pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Using a pregnane X receptor reporter system, our results demonstrated that isopimpinellin activated both PXR and its human ortholog SXR by recruiting coactivator SRC-1 in transfected cells. In CAR transfection assays, isopimpinellin counteracted the inhibitory effect of androstanol on full-length mCAR, a Gal4-mCAR ligand-binding domain fusion, and restored coactivator binding. Orally administered isopimpinellin induced hepatic mRNA expression of Cyp2b10, Cyp3a11, and GSTa in CAR(+/+) wild-type mice. In contrast, the induction of Cyp2b10 mRNA by isopimpinellin was attenuated in the CAR(-/-) mice, suggesting that isopimpinellin induces Cyp2b10 via the CAR receptor. Overall, the current data indicate that naturally occurring coumarins have diverse activities in terms of inducing various xenobiotic metabolizing enzymes based on their chemical structure.

Kleiner, Heather E. [Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Park Road 1-C, Smithville, TX 78957 (United States)], E-mail: hklein@lsuhsc.edu; Xia, Xiaojun; Sonoda, Junichiro [Howard Hughes Medical Institute, Gene Expression Laboratory, Salk Institute for Biological Sciences, La Jolla, CA 92037 (United States); Zhang, Jun [Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 (United States); Pontius, Elizabeth; Abey, Jane [Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Park Road 1-C, Smithville, TX 78957 (United States); Evans, Ronald M. [Howard Hughes Medical Institute, Gene Expression Laboratory, Salk Institute for Biological Sciences, La Jolla, CA 92037 (United States); Moore, David D. [Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 (United States); DiGiovanni, John [Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, Park Road 1-C, Smithville, TX 78957 (United States)

2008-10-15

246

Hydrogen sulfide in the mouse ductus arteriosus: a naturally occurring relaxant with potential EDHF function.  

PubMed

We have previously reported that bradykinin relaxes the fetal ductus arteriosus via endothelium-derived hyperpolarizing factor (EDHF) when other naturally occurring relaxants (prostaglandin E2, nitric oxide, and carbon monoxide) are suppressed, but the identity of the agent could not be ascertained. Here, we have examined in the mouse whether hydrogen sulfide (H2S) is a relaxant of the ductus and, if so, whether it may also function as an EDHF. We found in the vessel transcripts for the H2S synthetic enzymes, cystathionine-?-lyase (CSE) and cystathionine-?-synthase (CBS), and the presence of these enzymes was confirmed by immunofluorescence microscopy. CSE and CBS were distributed across the vessel wall with the former prevailing in the intimal layer. Both enzymes occurred within the endoplasmic reticulum of endothelial and muscle cells, whereas only CSE was located also in the plasma membrane. The isolated ductus contracted to inhibitors of CSE (d,l-propargylglycine, PPG) and CBS (amino-oxyacetic acid), and PPG contraction was attenuated by removal of the endothelium. EDHF-mediated bradykinin relaxation was curtailed by both PPG and amino-oxyacetic acid, whereas the relaxation to sodium nitroprusside was not affected by either treatment. The H2S donor sodium hydrogen sulfide (NaHS) was also a potent, concentration-dependent relaxant. We conclude that the ductus is endowed with a H2S system exerting a tonic relaxation. In addition, H2S, possibly via an overriding CSE source, qualifies as an EDHF. These findings introduce a novel vasoregulatory mechanism into the ductus, with implications for antenatal patency of the vessel and its transitional adjustments at birth. PMID:23376828

Baragatti, Barbara; Ciofini, Enrica; Sodini, Daria; Luin, Stefano; Scebba, Francesca; Coceani, Flavio

2013-02-01

247

Identification and characterization of naturally occurring splice variants of SAMHD1  

PubMed Central

Background Sterile Alpha Motif and HD domain-containing protein 1 (SAMHD1) is a recently identified host factor that restricts HIV-1 replication in dendritic and myeloid cells. SAMHD1 is a dNTPase that presumably reduces the cellular dNTP levels to levels too low for retroviral reverse transcription to occur. However, HIV-2 and SIV encoded Vpx counteracts the antiviral effects of SAMHD1 by targeting the protein for proteasomal degradation. SAMHD1 is encoded by a multiply spliced mRNA and consists of 16 coding exons. Results Here, we identified two naturally occurring splice variants lacking exons 8–9 and 14, respectively. Like wildtype SAMHD1, both splice variants localize primarily to the nucleus, interact with Vpx, and retain some sensitivity to Vpx-dependent degradation. However, the splice variants differ from full-length SAMHD1 in their metabolic stability and catalytic activity. While full-length SAMHD1 is metabolically stable in uninfected cells, both splice variants were inherently metabolically unstable and were rapidly degraded even in the absence of Vpx. Vpx strongly increased the rate of degradation of full-length SAMHD1 and further accelerated the degradation of the splice variants. However, the effect of Vpx on the splice variants was more modest due to the inherent instability of these proteins. Analysis of dNTPase activity indicates that neither splice variant is catalytically active. Conclusions The identification of SAMHD1 splice variants exposes a potential regulatory mechanism that could enable the cell to control its dNTPase activity on a post-transcriptional level.

2012-01-01

248

A naturally occurring point mutation confers broad range tolerance to herbicides that target acetolactate synthase.  

PubMed

Acetolactate synthase (ALS) inhibitors are among the most commonly used herbicides. They fall into four distinct families of compounds: sulfonylureas, imidazolinones, triazolopyrimidine sulfonanilides, and pyrimidinyl oxybenzoates. We have investigated the molecular basis of imidazolinone tolerance of two field isolates of cocklebur (Xanthium sp.) from Mississippi and Missouri. In both cases, tolerance was conferred by a form of ALS that was less sensitive to inhibitors than the wild type. The insensitivity pattern of the Mississippi isolate was similar to that of a commercial mutant of corn generated in the laboratory: ICI 8532 IT. Sequencing revealed that the same residue (Ala57-->Thr) was mutated in both Mississippi cocklebur and ICI 8532 IT corn. ALS from the Missouri isolate was highly insensitive to all the ALS herbicide families, similar in this respect to another commercial corn mutant: Pioneer 3180 IR corn. Sequencing of ALS from both plants revealed a common mutation that changed Trp552 to Leu. The sensitive cocklebur ALS cDNA, fused with a glutathione S-transferase, was functionally expressed in Escherichia coli. The recombinant protein had enzymatic properties similar to those of the plant enzyme. All the possible point mutations affecting Trp552 were investigated by site-directed mutagenesis. Only the Trp-->Leu mutation yielded an active enzyme. This mutation conferred a dramatically reduced sensitivity toward representatives of all four chemical families, demonstrating its role in herbicide tolerance. This study indicates that mutations conferring herbicide tolerance, obtained in an artificial environment, also occur in nature, where the selection pressure is much lower. Thus, this study validates the use of laboratory models to predict mutations that may develop in natural populations. PMID:7615543

Bernasconi, P; Woodworth, A R; Rosen, B A; Subramanian, M V; Siehl, D L

1995-07-21

249

Pharmacological properties of naturally occurring variants of the human norepinephrine transporter.  

PubMed

The human norepinephrine transporter (hNET) gene has five sequence polymorphisms that predict amino acid substitutions in the transporter protein: Val69Ile, Thr99Ile, Val245Ile, Val449Ile, and Gly478Ser. In order to functionally characterize the naturally occurring transporter variants, we used site-directed mutagenesis to establish the hNET variants and compared some basic pharmacological properties (uptake of norepinephrine and its inhibition by the tricyclic antidepressant desipramine) in COS-7 cells transiently expressing variant hNETs and wild-type hNET. None of the hNET variants displayed changes in the potency (Ki) of desipramine for inhibition of norepinephrine uptake. Furthermore, variants Val69Ile, Thr99Ile, ValZ45Ile, and Val449Ile did not affect kinetic constants (Km, Vmax) of norepinephrine uptake. However, COS-7 cells expressing the hNET variant Gly478Ser displayed an approximately four-fold increase in the Km for norepinephrine, while the Vmax was unaffected. The increase in the Km, which is equivalent to a four-fold reduction in the affinity of the variant hNET for its natural substrate norepinephrine, indicates that the glycine in position 478 is part of a substrate recognition domain. The reduced clearance of released norepinephrine by reuptake through the Gly478Ser variant might cause an increase in the synaptic and the circulating concentration of norepinephrine. Elevated norepinephrine concentrations have been associated with human diseases and it will be interesting to explore a possible contribution by the Gly478Ser variant to certain disease states. PMID:10898109

Runkel, F; Brüss, M; Nöthen, M M; Stöber, G; Propping, P; Bönisch, H

2000-07-01

250

Recombinant feline leukemia virus genes detected in naturally occurring feline lymphosarcomas.  

PubMed Central

Using a polymerase chain reaction strategy aimed at detecting recombinant feline leukemia virus (FeLV) genomes with 5' env sequences originating from an endogenous source and 3' env sequences resulting from FeLV subgroup A (FeLV-A), we detected recombinant proviruses in approximately three-fourths of naturally occurring thymic and alimentary feline lymphosarcomas (LSAs) and one-third of the multicentric LSAs from cats determined to be FeLV capsid antigen positive by immunofluorescence assay. In contrast, only 1 of 22 naturally arising FeLV-negative feline LSAs contained recombinant proviruses, and no recombinant env gene was detected in seven samples from normal tissues or tissues from FeLV-positive animals that died from other diseases. Four preferred structural motifs were identified in the recombinants; one is FeLV-B like (recognizing that FeLV-B itself is a product of recombination between FeLV-A and endogenous env genes), and three contain variable amounts of endogenous-like env gene before crossing over to FeLV-A-related sequences: (i) a combination of full-length and deleted env genes with recombination at sites in the middle of the surface glycoprotein (SU), (ii) the entire SU encoded by endogenous-like sequences, and (iii) the entire SU and approximately half of the transmembrane protein encoded by endogenous-like sequences. Additionally, three of the thymic tumors contained recombinant proviruses with mutations in the vicinity of the major neutralizing determinant for the SU protein. These molecular genetic analyses of the LSA DNAs correspond to our previous results in vitro and support the occurrence and association of viral recombinants and mutants in vivo in FeLV-induced leukemogenesis. Images

Sheets, R L; Pandey, R; Jen, W C; Roy-Burman, P

1993-01-01

251

Spectral Analysis of Naturally Occurring Methylxanthines (Theophylline, Theobromine and Caffeine) Binding with DNA  

PubMed Central

Nucleic acids exist in a dynamic equilibrium with a number of molecules that constantly interact with them and regulate the cellular activities. The inherent nature of the structure and conformational integrity of these macromolecules can lead to altered biological activity through proper targeting of nucleic acids binding ligands or drug molecules. We studied the interaction of naturally occurring methylxanthines such as theophylline, theobromine and caffeine with DNA, using UV absorption and Fourier transform infrared (FTIR) spectroscopic methods, and especially monitored their binding affinity in the presence of Mg2+ and during helix-coil transitions of DNA by temperature (Tm) or pH melting profiles. The study indicates that all these molecules effectively bind to DNA in a dose dependent manner. The overall binding constants of DNA-theophylline?=?3.5×103 M?1, DNA-theobromine?=?1.1×103 M?1, and DNA-Caffeine?=?3.8×103 M?1. On the other hand Tm/pH melting profiles showed 24–35% of enhanced binding activity of methylxanthines during helix-coil transitions of DNA rather than to its native double helical structure. The FTIR analysis divulged that theophylline, theobromine and caffeine interact with all the base pairs of DNA (A-T; G-C) and phosphate group through hydrogen bond (H-bond) interaction. In the presence of Mg2+, methylxanthines altered the structure of DNA from B to A-family. However, the B-family structure of DNA remained unaltered in DNA-methylxanthines complexes or in the absence of Mg2+. The spectral analyses indicated the order of binding affinity as “caffeine?theophylline>theobromine” to the native double helical DNA, and “theophylline?theobromine>caffeine to the denatured form of DNA and in the presence of divalent metal ions.

Johnson, Irudayam Maria; Prakash, Halan; Prathiba, Jeyaguru; Raghunathan, Raghavachary; Malathi, Raghunathan

2012-01-01

252

Natural Abundance Isotopic Fractionation in the Fermentation Reaction: Influence of the Fermentation Medium  

Microsoft Academic Search

The isotopic parameters of fermentation products provide reliable criteria for characterizing their carbohydrate precursors on the condition that the isotopic coefficients which relate individual sites in the products and in the reactants have strictly reproducible or predictible values. Since fermentation may be performed either in natural media (such as fruit juices) which exhibit variable compositions or in “synthetic” media prepared

Ben-Li Zhang; Yunianta; Claude Vallet; Maryvonne L. Martin

1997-01-01

253

Evaluation of occupational exposure to naturally occurring radioactive materials in the Iranian ceramics industry.  

PubMed

Zircon contains small amounts of uranium, thorium and radium in its crystalline structure. The ceramic industry is one of the major consumers of zirconium compounds that are used as an ingredient at ?10-20 % by weight in glaze. In this study, seven different ceramic factories have been investigated regarding the presence of radioactive elements with focus on natural radioactivity. The overall objective of this investigation is to provide information regarding the radiation exposure to workers in the ceramic industry due to naturally occurring radioactive materials. This objective is met by collecting existing radiological data specific to glaze production and generating new data from sampling activities. The sampling effort involves the whole process of glaze production. External exposures are monitored using a portable gamma-ray spectrometer and environmental thermoluminescence dosimeters, by placing them for 6 months in some workplaces. Internal routes of exposure (mainly inhalation) are studied using air sampling, and gross alpha and beta counting. Measurement of radon gas and its progeny is performed by continuous radon gas monitors that use pulse ionisation chambers. Natural radioactivity due to the presence of ²³?U, ²³²Th and ??K in zirconium compounds, glazes and other samples is measured by a gamma-ray spectrometry system with a high-purity germanium detector. The average concentrations of ²³?U and ²³²Th observed in the zirconium compounds are >3300 and >550 Bq kg?¹, respectively. The specific activities of other samples are much lower than in zirconium compounds. The annual effective dose from external radiation had a mean value of ?0.13 mSv y?¹. Dust sampling revealed the greatest values in the process at the powdering site and hand weighing places. In these plants, the annual average effective dose from inhalation of long-lived airborne radionuclides was 0.226 mSv. ²²²Rn gas concentrations in the glaze production plant and storage warehouse were found to range from 10 to 213 Bq m?³. In this study, the estimated annual effective doses to exposed workers were <1 mSv y?¹. PMID:21148590

Fathabadi, N; Farahani, M V; Amani, S; Moradi, M; Haddadi, B

2010-12-09

254

Alternatives for the disposal of NORM (naturally occurring radioactive materials) wastes in Texas  

SciTech Connect

Some of the Texas wastes containing naturally occurring radioactive materials (NORM) have been disposed of in a uranium mill tailings impoundment. There is currently no operating disposal facility in Texas to accept these wastes. As a result, some wastes containing extremely small amounts of radioactivity are sent to elaborate disposal sites at extremely high costs. The Texas Low-Level Radioactive Waste Disposal Authority has sponsored a study to investigate lower cost, alternative disposal methods for certain wastes containing small quantities of NORM. This paper presents the results of a multipathway safety analysis of various scenarios for disposing of wastes containing limited quantities of NORM in Texas. The wastes include pipe scales and sludges from oil and gas production, residues from rare-earth mineral processing, and water treatment resins, but exclude large-volume, diffuse wastes (coal fly ash, phosphogypsum). The purpose of the safety analysis is to define concentration and quantity limits for the key nuclides of NORM that will avoid dangerous radiation exposures under different waste disposal scenarios.

Nielson, K.K.; Rogers, V.C. (Rogers Associates Engineering Corporation, Salt Lake City, UT (USA)); Pollard, C.G. (Texas Low-Level Radioactive Waste Disposal Authority, Austin (USA))

1989-11-01

255

Two Naturally Occurring Terpenes, Dehydrocostuslactone and Costunolide, Decrease Intracellular GSH Content and Inhibit STAT3 Activation  

PubMed Central

The main purpose of the present study is to envisage the molecular mechanism of inhibitory action ofdehydrocostuslactone (DCE) andcostunolide (CS), two naturally occurring sesquiterpene lactones, towards the activation of signal transducer and activator of transcription 3 (STAT3). We report that, in human THP-1 cell line, they inhibit IL-6-elicited tyrosine phosphorylation of STAT3 and its DNA binding activity with EC50 of 10 µM with concomitantdown-regulation ofthe phosphorylation of the tyrosine Janus kinases JAK1, JAK2 and Tyk2. Furthermore, these compounds that contain an ?-?-unsatured carbonyl moiety and function as potent Michael reaction acceptor, induce a rapid drop in intracellular glutathione (GSH) concentration by direct interaction with it, thereby triggering S-glutathionylation of STAT3. Dehydrocostunolide (HCS), the reduced form of CS lacking only the ?-?-unsaturated carbonyl group, fails to exert any inhibitory action. Finally, the glutathione ethylene ester (GEE), the cell permeable GSH form, reverts the inhibitory action of DCE and CS on STAT3 tyrosine phosphorylation. We conclude that these two sesquiterpene lactones are able to induce redox-dependent post-translational modification of cysteine residues of STAT3 protein in order to regulate its function.

Butturini, Elena; Cavalieri, Elisabetta; Carcereri de Prati, Alessandra; Darra, Elena; Rigo, Antonella; Shoji, Kazuo; Murayama, Norie; Yamazaki, Hiroshi; Watanabe, Yasuo; Suzuki, Hisanori; Mariotto, Sofia

2011-01-01

256

Neuropathogenesis of naturally occurring encephalitis caused by Listeria monocytogenes in ruminants.  

PubMed

Listeriosis is a serious food-borne disease with increasing frequency in humans and ruminants. Despite the facts that in both hosts, listeriosis can occur as rhombencephalitis and ruminants are a reservoir of Listeria monocytogenes (LM) strains pathogenic for humans, little work has been done on the pathogenesis in ruminants. This study investigates the neuropathogenesis of listeric encephalitis in over 200 natural cases in cattle, sheep and goats by analyzing anatomical distribution, severity, bacterial load and temporal evolution of the lesions. Our results suggest that LM gains access to the brainstem of all three species via axonal migration not only along the trigeminal nerve, but also along other nerves. The ensuing encephalitis does not remain restricted to the brainstem. Rather, LM spreads further from the brainstem into rostral brain regions likely by intracerebral axonal migration. Significant differences in severity of the lesions and bacterial load were found between cattle and small ruminants, which may be caused by species-specific properties of antibacterial immune responses. As histopathological lesions of human rhombencephalitis caused by LM strongly resemble those of ruminants, the disease likely has a similar pathogenesis in both hosts. PMID:19476464

Oevermann, Anna; Di Palma, Stefano; Doherr, Marcus G; Abril, Carlos; Zurbriggen, Andreas; Vandevelde, Marc

2009-05-20

257

Regulatory Initiatives for Control and Release of Technologically Enhanced Naturally-Occurring Radioactive Materials  

SciTech Connect

Current drafts of proposed standards and suggested State regulations for control and release of technologically-enhanced naturally-occurring radioactive material (TENORM), and standards for release of volumetrically-contaminated material in the US are reviewed. These are compared to the recommendations of the International Atomic Energy Association (IAEA) Safety Series and the European Commission (EC) proposals. Past regulatory efforts with respect to TENORM in the US dealt primarily with oil-field related wastes. Currently, nine states (AK, GA, LA, MS, NM, OH, OR SC, TX) have specific regulations pertaining to TENORM, mostly based on uranium mill tailings cleanup criteria. The new US proposals are dose- or risk-based, as are the IAEA and EC recommendations, and are grounded in the linear no threshold hypothesis (LNT). TENORM wastes involve extremely large volumes, particularly scrap metal and mine wastes. Costs to control and dispose of these wastes can be considerable. The current debate over the validity of LNT at low doses and low dose rates is particularly germane to this discussion. Most standards setting organizations and regulatory agencies base their recommendations on the LNT. The US Environmental Protection Agency has released a draft Federal Guidance Report that recommends calculating health risks from low-level exposure to radionuclides based on the LNT. However, some scientific and professional organizations are openly questioning the validity of LNT and its basis for regulations, practices, and costs to society in general. It is not clear at this time how a non-linear regulatory scheme would be implemented.

Egidi, P.V.

1999-03-02

258

The role of bacterial nanowires on naturally-occurring electrical fields  

NASA Astrophysics Data System (ADS)

Microbial activity is shown to significantly contribute to the naturally occurring electrical fields observed in geologic media. To investigate the source mechanism of this phenomenon we constructed models of the subsurface by inoculating saturated sand columns with the bacterium Shewanella oneidensis MR-1 and a mutant strain as control. S. oneidensis (and other microoragnisms) are known to develop a structured network of electron- conductive bacterial nanowires as a response to electron acceptor limitation conditions. We show that strong voltage gradients (SP) were concomitant with redox potential gradients in the MR-1 column but absent in the mutant columns. We hypothesize that deeply submerged (suffocating) cells gain access to oxygen through the nanowire network which extends to the groundwater - atmospheric air interface. The nanowires serve as conduits for transfer electrons from bacteria in the anaerobic part of the column to bacteria at the surface that have access to oxygen. We suggest that this process is directly linked with SP and redox gradients that develop across the column. We also observed that in the absence of conductive nanowires (or other conductors) redox potential gradients do not necessarily promote SP gradients as documented in our control columns. Our results suggest that microbial activity and nanowires greatly impact the electrical properties of porous materials and contribute to our understanding of the mechanisms that underlie geophysical methods for mapping microbial activity in near subsurface environments.

Hill, E. A.; Ntarlagiannis, D.; Atekwana, E. A.; Gorby, Y. A.

2007-05-01

259

? arcades: recurring motifs in naturally occurring and disease-related amyloid fibrils  

PubMed Central

Amyloid fibrils are filamentous protein aggregates that accumulate in diseases such as Alzheimer’s or type II diabetes. The amyloid-forming protein is disease specific. Amyloids may also be formed in vitro from many other proteins, after first denaturing them. Unlike the diverse native folds of these proteins, their amyloids are fundamentally similar in being rigid, smooth-sided, and cross-?-structured, that is, with ? strands running perpendicular to the fibril axis. In the absence of high-resolution fibril structures, increasingly credible models are being derived by integrating data from a crossfire of experimental techniques. Most current models of disease-related amyloids invoke “? arcades,” columnar structures produced by in-register stacking of “? arches.” A ? arch is a strand-turn-strand motif in which the two ? strands interact via their side chains, not via the polypeptide backbone as in a conventional ? hairpin. Crystal structures of ?-solenoids, a class of proteins with amyloid-like properties, offer insight into the ?-arc turns found in ? arches. General conformational and thermodynamic considerations suggest that complexes of 2 or more ? arches may nucleate amyloid fibrillogenesis in vivo. The apparent prevalence of ? arches and their components have implications for identifying amyloidogenic sequences, elucidating fibril polymorphisms, predicting the locations and conformations of ? arcs within amyloid fibrils, and refining existing fibril models.—Kajava, A. V., Baxa, U., Steven, A. C. ? arcades: recurring motifs in naturally occurring and disease-related amyloid fibrils.

Kajava, Andrey V.; Baxa, Ulrich; Steven, Alasdair C.

2010-01-01

260

Artificially Induced and Naturally Occurring Hydraulic Tomography for Characterizing Groundwater Basins  

NASA Astrophysics Data System (ADS)

A hydraulic tomographic survey is an innovative approach to characterize the heterogeneity of hydraulic parameters in the subsurface. During hydraulic tomography, spatial and temporal pressure responses from a series of aquifer excitations at different locations and times are collected. Such a data set provides additional independent constraints and makes groundwater inverse problems better posed. Based on the sequential successive linear estimator approach (Yeh and Liu, 2000), we developed an iterative sequential successive linear estimator to analyze the data sets for estimating hydraulic conductivity and specific storage of three-dimensional groundwater basins. To account for the temporal correlation of transient heads, we treated head responses at different time steps in one pumping test as one dataset, whereas head responses from different pumping tests are incorporated into the inverse approach sequentially. After the sequential inclusion of the data sets from different excitations, we iterate the process to improve our estimates. Our study shows that the head is highly correlated with specific storage at early time during a pumping test and with hydraulic conductivity at late time. Consequently, to obtain good estimates of both hydraulic conductivity and specific storage, the head responses at both early and late time are needed. Our new inverse approach has been implemented on a parallel computing platform and applications of our new method for large-scale, naturally occurring hydraulic tomographic surveys are discussed using changes in external loadings on aquifers (such as river stages, barometric pressures, precipitations, surface water reservoirs, trains, etc.).

Zhu, J.; Yeh, T. J.

2004-12-01

261

Pre-concentration of naturally occurring radionuclides and the determination of (212)Pb from fresh waters.  

PubMed

A novel technique has been developed for determining the (212)Pb activity of fresh waters. This is of interest to environmental monitoring programmes that utilise gross ?-activity methods to screen for anthropogenic radionuclides. The contribution from (212)Pb varies, and is difficult to experimentally measure due to its relatively short half-life (t(½) = 10.6 h) and low environmental activity (<0.1 Bq l(-1)). The use of a three-stage technique that encompasses a unique form of pre-concentration, separation and analysis by liquid scintillation counting allows a lower detection limit of 0.006 Bq l(-1) with a chemical yield of 92.5 ± 5.6%. The measurement can be obtained within 7 h of sample collection, and is calculated using the radioactive decay of (212)Bi. Other naturally occurring radionuclides may also be extracted using the pre-concentration stage of the technique, with efficiencies above 90% at a range of pH values. PMID:21306802

Burnett, J L; Croudace, I W; Warwick, P E

2011-04-01

262

Sperm morphology, motility, and velocity in naturally occurring polyploid European weatherfish (Misgurnus fossilis L.).  

PubMed

Spontaneous polyploidy has been frequently documented in various fish species. This process may lead to disruption in testicular development and function. In the present study, sperm morphology and motility, elements critical to male fertility, were characterized in the naturally occurring triploid (3n) and tetraploid (4n) European weatherfish, Misgurnus fossilis L. (Teleostei, Cobitidae) inhabiting the upper reaches of the Lužnice River in the Czech Republic. Sperm with smaller heads, shorter flagella, and a lower number of mitochondria was observed in 3n specimens compared with 4n, but no differences were observed in size of midpiece or ultrastructure of sperm. Similar to most teleosts, the European weatherfish spermatozoon lacked an acrosome and consisted of a head (containing DNA), a midpiece (containing mitochondria and proximal and distal centrioles), and a flagellum with 9 + 2 microtubular structure. Sperm velocity was significantly lower in individuals with 4n compared with 3n, whereas no difference in sperm motility was observed. The stepwise linear regression reported significant negative correlations between sperm velocity and length of sperm head (r = -0.92, P < 0.01). In conclusion, the data reported no effect of polyploidy on sperm ultrastructure and motility in the European weatherfish, although it can affect sperm velocity, possibly through differences in head size and the number of mitochondria, which provide ATP for sperm movement. PMID:23664795

Alavi, Sayyed Mohammad Hadi; Drozd, Bo?ek; Hatef, Azadeh; Flajšhans, Martin

2013-05-10

263

Studies of two naturally occurring compounds which effect release of acetylcholine from synaptosomes. [Leptinotarsa decemlineata  

SciTech Connect

Two naturally occurring compounds which effect the release of neurotransmitter from synaptosomes have been purified to apparent homogeneity. Iotrochotin (IOT) isolated from wound exudate of the Caribbean purple bleeder sponge promotes release in a manner that is independent of the extracellular Ca/sup 2 +/ ion concentration. Leptinotarsin (LPT-d), a protein taken from hemolymph of the Colorado potato beetle, Leptinotarsa decemlineata, stimulates Ca/sup 2 +/-dependent release. IOT is slightly acidic and has a molecular weight of approximately 18 kD. (/sup 3/H)acetylcholine which has been introduced into synaptosomes as (/sup 3/H)choline can be released by IOT. The toxin releasable pool of labelled neurotransmitter is not depleted by depolarization of the synaptosomes with high potassium, and therefore seems to be primarily extravesicular. LPT-d is a larger protein (molecular weight = 45 kD) than IOT, and seems to effect primarily vesicular release by opening at least one type of presynaptic Ca/sup 2 +/ channel. The facilitatory effects of the toxin on synaptosomal release can be inhibited by inorganic Ca/sup 2 +/ channel antagonists, but are not generally affected by organic antagonists.

Koenig, M.L.

1985-01-01

264

An overview of naturally occurring radioactive materials (NORM) in the petroleum industry  

SciTech Connect

Oil and gas extraction and processing operations sometimes accumulate naturally occurring radioactive materials (NORM) at concentrations above normal in by-product waste streams. Results from NORM surveys indicate that radionuclide concentrations can be quite variable, ranging from undetectable to extremely high levels. To date, efforts to characterize the geographic distribution of NORM have been limited by poor statistical representation. In addition, the fate of NORM in the environment has not been fully defined, and few human health risk assessment have been conducted. Both the petroleum industry and regulators are becoming increasingly concerned about the presence of NORM. At present, most existing federal environmental regulations do not address oil and gas NORM, and only a few states have developed regulatory programs. Available data suggest that the occurrence of NORM (and associated health risks) is significant enough to warrant increased regulatory control. However, before these regulations can be developed, additional research is needed to (1) better characterize the occurrence and distribution of NORM throughout the industry, (2) quantify hazards posed by NORM to industry workers and the general public, and (3) develop effective waste treatment and minimization technologies that will lower the risk associated with NORM and reduce disposal costs.

Smith, K.P.

1992-12-01

265

Antioxidant effect of naturally occurring xanthines on the oxidative damage of DNA bases  

NASA Astrophysics Data System (ADS)

The repair of the oxidised radicals of adenine and guanosine by several naturally occurring xanthines was studied. Each pair of DNA purine/xanthine was made to react with the sulphate radical and the decrease of the concentration of both compounds was measured by HPLC as a function of irradiation time. The results show that xanthine efficiently prevents the oxidation of the two DNA purines. Theophyline and paraxanthine repair the oxidised radical of adenine but not the one from guanosine. Theobromine and caffeine do not show any protecting effect. An order of the oxidation potentials of all the purines studied is proposed. La réparation des radicaux oxydés de l'adénine et de la guanosine par des xanthines naturelles a été étudiée en soumettant chaque paire base de l'ADN/xanthine à l'oxydation par le radical sulfate et en mesurant par HPLC la disparition des deux composés en fonction du temps d'irradiation. Les résultats montrent que la xanthine joue un rôle protecteur efficace contre l'oxydation des deux purines de l'ADN. La théophyline et la paraxanthine réparent le radical oxydé de l'adénine mais pas celui de la guanosine. La théobromine et la cafeíne n'ont pas d'effet protecteur. Un ordre de potentiels d'oxydation des purines étudiées est proposé.

Vieira, A. J. S. C.; Telo, J. P.; Pereira, H. F.; Patrocínio, P. F.; Dias, R. M. B.

1999-01-01

266

Relationships of phytomacrofauna to surface area in naturally occurring macrophyte stands  

USGS Publications Warehouse

Most studies of the relationships between freshwater macrophytes and phytomacrofauna, or the macroinvertebrates associated with the macrophytes, have been based on individual plant collections or samples from monotypic plant stands. We describe the phytomacrofauna assemblages within naturally occurring, taxonomically mixed stands, and consider how macrophyte surface area and plant morphology influenced phytomacrofauna diversity and abundance. Samples of submersed macrophytes and phytomacrofauna were collected April-November 1979 in Anchor Bay of Lake St. Clair. Only the portions of macrophytes within the water column and invertebrates from above the sediment were considered. Densities of phytomacrofauna were not consistently related to fluctuations in macrophyte surface area, indicating that the use of macrophyte structure by the invertebrates changed during the year. Both the abundance and species richness of the phytomacrofauna were strongly related to macrophyte species richness reflecting the response of the invertebrates to the structural heterogeneity in taxonomically mixed stands. Vertically heterogeneous stands with an understory of Chara and an overstory of vascular macrophytes, for example, were likely to contain more invertebrates than stands with only one macrophyte taxon.

Brown, Charles L.; Poe, Thomas P.; French, John R. P., III; Schloesser, Donald W.

1988-01-01

267

Evaluation of naturally occurring radioactive materials (NORM) in the South Western oil wells of Iran.  

PubMed

An investigation was carried out to find out the concentration of Naturally Occurring Radioactive Materials (NORMs) in an oil production unit, an evaporation pond, and a drilling site in the Khuzestan province, in south west Iran the 4th largest oil producing country in the world. The nuclides (232)Th and (40)K were determined in soil samples and (226)Ra was analyzed in both soil and water. The (232)Th ranged between 8.7 and 403 Bq kg(-1), while the minimum concentration for (40)K was much larger, i.e. 82 Bq kg(-1) and its maximum concentration was 815 Bq kg(-1). Soil samples indicated very low concentrations of (226)Ra, typically between 10.6 and 42.1 Bq kg(-1) with some exceptions of 282, 602, and even 1480 Bq kg(-1). Also, the range for (226)Ra in water was less from 0.1 to a maximum 30.3 Bq L(-1). Results show that on average, NORM concentrations in these areas are lower in comparison with the usual concentration levels in typical oil and gas fields, but despite this fact, necessary measures have to be taken in order to minimize the environmental impact of radioactive materials. PMID:22321893

Khodashenas, Alireza; Roayaei, Emad; Abtahi, Seyed Mojtaba; Ardalani, Elham

2012-02-08

268

Comparison of naturally occurring shale bitumen asphaltene and retorted shale oil asphaltene  

SciTech Connect

Asphaltene is ubiquitously present in both the natural occurring bitumen and the retorted shale oil. Very few cases for the comparison of asphaltene properties are available in the literature. In this research, a comparison of the shale bitumen asphaltene and the retorted shale oil asphaltene was undertaken to investigate structural changes during thermal cracking. This was accomplished by means of elemental chemical analysis, infrared spectra, proton nmr spectra, and carbon-13 spectra of the bitumen asphaltenes and asphaltenes derived from shale oil retorted at 425 and 500/sup 0/C. Elemental analysis indicated that asphaltenes derived from retorted shale oils have smaller H/C ratio and smaller oxygen and sulfur contents, but greater nitrogen content than that derived from shale bitumen. Infrared spectra revealed that the retorted shale oil asphaltenes have greater pyrrolic N-H and hydrogen bonded O-H or N-H absorption than the shale bitumen asphaltene. Retorted shale oil asphaltenes have relatively higher aromaticity, lower degree of substitution of the aromatic sheet, and shorter alkyl substituents, which indicated that the main reactions in the retorting process are carbon-carbon bond fission and intramolecular aromatization.

Shue, F.F.; Yen, T.F.

1980-01-01

269

Microbial Utilization of Naturally Occurring Hydrocarbons at the Guaymas Basin Hydrothermal Vent Site †  

PubMed Central

The Guaymas Basin (Gulf of California; depth, 2,000 m) is a site of hydrothermal activity in which petroliferous material is formed by thermal alteration of deposited planktonic and terrestrial organic matter. We investigated certain components of these naturally occurring hydrocarbons as potential carbon sources for a specific microflora at these deep-sea vent sites. Respiratory conversion of [1-14C]hexadecane and [1(4,5,8)-14C]naphthalene to 14CO2 was observed at 4°C and 25°C, and some was observed at 55°C, but none was observed at 80°C. Bacterial isolates were capable of growing on both substrates as the sole carbon source. All isolates were aerobic and mesophilic with respect to growth on hydrocarbons but also grew at low temperatures (4 to 5°C). These results correlate well with previous geochemical analyses, indicating microbial hydrocarbon degradation, and show that at least some of the thermally produced hydrocarbons at Guaymas Basin are significant carbon sources to vent microbiota.

Bazylinski, Dennis A.; Wirsen, Carl O.; Jannasch, Holger W.

1989-01-01

270

Naturally occurring anti-band 3 antibodies have a unique affinity for C3.  

PubMed Central

Naturally occurring anti-band 3 antibodies appear to mediate opsonization of oxidatively stressed and in vivo aged red cells. Their low concentration in plasma (< 100 ng/ml) and weak affinity (estimated association constant, 5-7 x 10(6) l/mol) contrasted with their biological efficiency. In compensating for their inadequate properties they have an affinity for C3 at a site independent of the antigen binding domain, with an estimated association constant of 2-3 x 10(5) l/mol. Though weak, their binding to C3 was about 100 times higher than that of whole IgG, which is known to have an affinity for C3. The affinity for C3 may render these antibodies preferred targets of the short-lived nascent C3b and result in a preferential C3b-anti-band 3 complex formation. C3b-IgG complexes represent the best opsonins and can nucleate alternative complement pathway C3 convertases by which opsonization is further enhanced. Images Figure 1 Figure 2

Lutz, H U; Nater, M; Stammler, P

1993-01-01

271

Radiological dose assessment related to management of naturally occurring radioactive materials generated by the petroleum industry  

SciTech Connect

A preliminary radiological dose assessment of equipment decontamination, subsurface disposal, landspreading, equipment smelting, and equipment burial was conducted to address concerns regarding the presence of naturally occurring radioactive materials (NORM) in production waste streams. The assessment estimated maximum individual dose equivalents for workers and the general public. Sensitivity analyses of certain input parameters also were conducted. On the basis of this assessment, it is concluded that (1) regulations requiring workers to wear respiratory protection during equipment cleaning operations are likely to result in lower worker doses, (2) underground injection and downhole encapsulation of NORM wastes present a negligible risk to the general public, and (3) potential doses to workers and the general public related to smelting NORM-contaminated equipment can be controlled by limiting the contamination level of the initial feed. It is recommended that (1) NORM wastes be further characterized to improve studies of potential radiological doses; (2) states be encouraged to permit subsurface disposal of NORM more readily, provided further assessments support this study; results; (3) further assessment of landspreading NORM wastes be conducted; and (4) the political, economic, sociological, and nonradiological issues related to smelting NORM-contaminated equipment be studied to fully examine the feasibility of this disposal option.

Smith, K.P.; Blunt, D.L.; Williams, G.P. [Argonne National Lab., IL (United States). Environmental Assessment Div.; Tebes, C.L. [Univ. of Illinois, Urbana, IL (United States)

1996-09-01

272

Novel class of glutathione transferases from cyanobacteria exhibit high catalytic activities towards naturally occurring isothiocyanates  

PubMed Central

In the present paper, we report a novel class of GSTs (glutathione transferases), called the Chi class, originating from cyanobacteria and with properties not observed previously in prokaryotic enzymes. GSTs constitute a widespread multifunctional group of proteins, of which mammalian enzymes are the best characterized. Although GSTs have their origin in prokaryotes, few bacterial representatives have been characterized in detail, and the catalytic activities and substrate specificities observed have generally been very modest. The few well-studied bacterial GSTs have largely unknown physiological functions. Genome databases reveal that cyanobacteria have an extensive arsenal of glutathione-associated proteins. We have studied two cyanobacterial GSTs which are the first examples of bacterial enzymes that are as catalytically efficient as the best mammalian enzymes. GSTs from the thermophile Thermosynechococcus elongatus BP-1 and from Synechococcus elongatus PCC 6301 were found to catalyse the conjugation of naturally occurring plant-derived isothiocyanates to glutathione at high rates. The cyanobacterial GSTs studied are smaller than previously described members of this enzyme family, but display many of the typical structural features that are characteristics of GSTs. They are also active towards several classical substrates, but at the same moderate rates that have been observed for other GSTs derived from prokaryotes. The cloning, expression and characterization of two cyanobacterial GSTs are described. The possible significance of the observed catalytic properties is discussed in the context of physiological relevance and GST evolution.

Wiktelius, Eric; Stenberg, Gun

2007-01-01

273

Myricetin and Quercetin Are Naturally-Occurring Co-substrates of Cyclooxygenases In Vivo1  

PubMed Central

Bioflavonoids are ubiquitously present in the plant kingdom, and some of them are presently being sold as healthy dietary supplements around the world. Recently, it was shown that some of the dietary polyphenols were strong stimulators of the catalytic activity of cyclooxygenase I and II, resulting in increased formation of certain prostaglandin (PG) products in vitro and also in intact cells in culture. In the present study, we investigated the effect of two representative dietary compounds, quercetin and myricetin, on plasma and tissue levels of several PG products in normal Sprague-Dawley rats. We found that these two dietary bioflavonoids could strongly stimulate the formation of PG products in vivo in a time-dependent manner, and the stimulatory effect of these two bioflavonoids was dose-dependent with a unique biphasic pattern. At lower doses (<0.3 mg/kg b.w.), they strongly stimulated the formation of PGE2, but at higher doses (>0.3 mg/kg b.w.), there was a dose-dependent reduction of the stimulatory effect. These results provide support for the hypothesis that some of the bioflavonoids are naturally-occurring physiological co-substrates for the cyclooxygenases in vivo.

Bai, Hyoung-Woo; Zhu, Bao T.

2009-01-01

274

Use of naturally occurring mercury to determine the importance of cutthroat trout to Yellowstone grizzly bears  

USGS Publications Warehouse

Spawning cutthroat trout (Oncorhynchus clarki (Richardson, 1836)) are a potentially important food resource for grizzly bears (Ursus arctos horribilis Ord, 1815) in the Greater Yellowstone Ecosystem. We developed a method to estimate the amount of cutthroat trout ingested by grizzly bears living in the Yellowstone Lake area. The method utilized (i) the relatively high, naturally occurring concentration of mercury in Yellowstone Lake cutthroat trout (508 ?? 93 ppb) and its virtual absence in all other bear foods (???6 ppb), (ii) hair snares to remotely collect hair from bears visiting spawning cutthroat trout streams between 1997 and 2000, (iii) DNA analyses to identify the individual and sex of grizzly bears leaving a hair sample, (iv) feeding trials with captive bears to develop relationships between fish and mercury intake and hair mercury concentrations, and (v) mercury analyses of hair collected from wild bears to estimate the amount of trout consumed by each bear. Male grizzly bears consumed an average of 5 times more trout/kg bear than did female grizzly bears. Estimated cutthroat trout intake per year by the grizzly bear population was only a small fraction of that estimated by previous investigators, and males consumed 92% of all trout ingested by grizzly bears.

Felicetti, L. A.; Schwartz, C. C.; Rye, R. O.; Gunther, K. A.; Crock, J. G.; Haroldson, M. A.; Waits, L.; Robbins, C. T.

2004-01-01

275

Investigation of the activity level and radiological impacts of naturally occurring radionuclides in blast furnace slag.  

PubMed

The activity level and possible radiological impacts of naturally occurring radionuclides on the health of workers and members of the public, as a result of utilisation of blast furnace slag (BFS) samples as a substitute for aggregate in road construction were investigated by using a gamma-ray spectrometer and potential exposure scenarios given in Radiation Protection 122. The mean activity concentrations of the (226)Ra, (232)Th and (40)K in BFS samples were found to be 152.4, 54.9 and 183.1 Bq kg(-1), respectively. These values are compared with typical values measured in BFS samples from the European Union countries, which are 270, 70 and 240 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The values of radium equivalent activity index calculated for BFS samples were within the recommended safety limits. The highest total annual effective doses evaluated as 0.9 and 0.4 mSv y(-1) for members of the public and workers, respectively, were lower than the annual limit of 1 mSv y(-1). PMID:22826355

U?ur, F A; Turhan, S; Sahan, H; Sahan, M; Gören, E; Gezer, F; Ye?ingil, Z

2012-07-22

276

Differential modulation of the genotoxicity of food carcinogens by naturally occurring monomeric and dimeric polyphenolics.  

PubMed

Naturally occurring dimeric polyphenolics and their gallate esters were isolated from grape seeds, almond fruits, and apple skin, and their ability to modulate the mutagenicity of food carcinogens was studied in the Ames test, and compared to that of the monomeric green tea flavonols, (+)-catechin and (-)-epicatechin. Neither the monomeric nor the dimeric polyphenols and their galloylated derivatives influenced the mutagenic activity elicited by the indirectly acting food carcinogens benzo[a]pyrene and 2-amino-3-methylimidazo-[4,5-f]quinoline (IQ), in the presence of a hepatic activation system derived from Aroclor 1254-treated rats; the only exception was the B7 dimer, which, at concentrations above 1 microM, suppressed the mutagenicity of IQ. None of the polyphenolics modulated the mutagenic activity elicited by the directly acting carcinogen N'-methyl-N'-nitro-nitrosoguanidine (MNNG). In contrast, all the dimeric polyphenols and the galloylated metabolites, at concentrations over 1 microM, potentiated the mutagenic activity induced by the indirectly acting carcinogen N-nitrosopyrrolidine, in the presence of an activation system derived from isoniazid-treated rats. In conclusion, dimeric polyphenols and galloylated derivatives of plant origin are unlikely to influence the initiation stage of the carcinogenicity of chemicals through mechanisms that involve inhibition of their cytochrome P450-mediated bioactivation or scavenging of the reactive, genotoxic intermediates. PMID:10712742

Catterall, F; Souquet, J M; Cheynier, V; de Pascual-Teresa, S; Santos-Buelga, C; Clifford, M N; Ioannides, C

2000-01-01

277

Chlorination of 4-hydroxycinnamic acid and its toxic risk as a natural occurring water contaminant  

SciTech Connect

During the decay process of plant material a number of phenolic compounds are released into the environment. Previous studies on water courses have shown that five phenolic acids derived from plants predominate with 4-hydroxycinnamic acid as the major compound. Many of these compounds can travel through the soil matrix and enter a water stream. However, water supplies are routinely chlorinated which leads to the chemical chlorination of phenolic water contaminants. These naturally occurring phenolics may therefore change their chemical and biological behavior and probably become, after chlorination, increasingly toxic. Although the occurrence of water compounds in tap water have been increasingly investigated with focus on industrial water pollutants, it is not fully understood to what extent the decay of plant material contributes to phenolic water contamination. Great concern about routine water chlorination has been expressed, because of the chlorination of aliphatic and aromatic water contaminants possibly accompanied by a change in their chemical and biological behavior and the synthesis of organochlorine derivatives. The present situation does not allow any prediction of the chemical and biological behavior of the parent compound nor is it possible to anticipate the amount and potential risk of its organochlorine derivatives. The objective of the present work was to study the chemical behavior of plant-derived phenolic acids under conditions similar to the routine water chlorination. The toxicity of the chlorophenoic mixtures was assessed on a Escherichia coli strain similar to that found in the human intestine.

Borlakoglu, J.T.; Kickuth, R.

1986-12-01

278

Affiliative relationships between adult males and immature group members in naturally occurring ringtailed lemurs (Lemur catta).  

PubMed

Affiliative relations between adult males and immature group members were studied in three naturally occurring groups of ringtailed lemurs (Lemur catta) over a 12-month period at Beza-Mahafaly Reserve, southwestern Madagascar. No statistically significant difference was found in rates of affiliative interactions between adult males and older immatures (juveniles and adolescents) over reproductive seasons. However, some of the adult males in two focal groups increased their rates of affiliative behaviors with older immatures during the lactation and subsequent 1993 postmigration periods. Female involvement with infants during lactation season, the increasing independence of juveniles and adolescents, and length of male tenure may be factors contributing to such a pattern. Neither adult males nor immatures were significantly responsible for the initiation and maintenance of proximity in male-immature dyadic interactions. Neither dominance rank nor age-class of the adult male affected their rates of affiliative behavior with immatures. The majority of focal males exhibited an interest in infants and occasionally participated in alloparental care. It is suggested that adult males can benefit from affiliative relations with immatures in terms of opportunities for greater spatial centrality in the group, which can lead to enhanced predator protection and greater opportunities to develop affiliative relationships with females. Immatures can benefit from affiliation with males in relation to enhanced predator detection and protection, alloparental care, and opportunities to develop social skills. PMID:9209574

Gould, L

1997-06-01

279

Simultaneous determination of three naturally occurring estrogens in environmental waters by high-performance liquid chromatography.  

PubMed

A simple, sensitive and accurate reversed-phase high-performance liquid chromatographic (HPLC) method for simultaneous determination of three naturally occurring estrogenic steroids including estrone (E1), 17?-estradiol (E2) and estriol (E3) in environmental water samples was developed. Analytes were extracted with ethyl acetate solvents and preconcentrated prior to HPLC analysis. Separations were accomplished in <20 min using a reversed-phase C(18) column (4.6×250 mm id, 5 ?m) with a gradient elution of mobile phase containing 3.0 mM ammonium acetate/acetonitrile mixtures (flow rate, 1.0 mL/min). UV light absorption responses at 205 nm were linear over a wide concentration range from 100,000 ?g/L to the detection limits of 0.96 ?g/L E1, 0.64 ?g/L E2 and 0.78 ?g/L E3. Quantitation was carried out by the peak area method. The relative standard deviation for the analysis of three estrogens was <3.0%. This method was applied for the simultaneous determination of estrogens in environmental water samples collected in Zhejiang, China. The higher concentrations of both E2 and E3 were found in Tang River and West Lake waters, and E1 was detected in lake water only. All three estrogens were below the detection limits in rain waters. PMID:21793210

Wang, Chengjun; Xu, Chunmei; Chen, Fan; Tang, Xuejiao

2011-07-27

280

Neuroprotective action and free radical scavenging activity of Guttiferone-A, a naturally occurring prenylated benzophenone.  

PubMed

Reactive oxygen species (ROS) are important mediators in a number of neurodegenerative diseases and molecules capable of scavenging ROS may be a feasible strategy for protecting neuronal cells. We previously demonstrated a powerful iron-chelating action of Guttiferone-A (GA), a naturally occurring polyphenol, on oxidative stress injuries initiated by iron overload. Here we addressed the neuroprotective potential of GA in hydrogen peroxide and glutamate-induced injury on rat's primary culture of cortical neurons and PC12 cells, respectively, and antioxidant properties concerning scavenging and anti-lipoperoxidative activities in cell-free models. The decrease in cell viability induced by each of the toxins, assessed by [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] (MTT) assay, was significantly attenuated by GA. In addition, GA was found to be a potent antioxidant, as shown by (i) inhibition of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical reduction (EC50=20.0??M), (ii) prevention against chemically or electrochemically generated superoxide radicals, (iii) inhibition of spontaneous brain lipid peroxidation and (iv) interference with the Fenton reaction. These results indicate that GA exerts neuroprotective effects against H2O2 or glutamate toxicity and its antioxidant activity, demonstrated in vitro, could be at least partly involved. They also suggest a promising potential for GA as a therapeutic agent against neurodegenerative diseases involving ROS and oxidative damage. PMID:23115059

Nuñez-Figueredo, Y; García-Pupo, L; Ramírez-Sánchez, J; Alcántara-Isaac, Y; Cuesta-Rubio, O; Hernández, R D; Naal, Z; Curti, C; Pardo-Andreu, G L

2012-10-31

281

Inhibition of colony formation of Hela cells by naturally occurring and synthetic agents.  

PubMed

The present study compared the effects of naturally occurring extracts or compound in combination with synthetic selenium compounds on the colony formation and nucleic acid synthesis of cultured human cervical epitheloid carcinoma cells (Hela). Crude extract of bean (Phaseolus vulgaris) or purified lectin from red kidney bean (Phaseolus vulgaris) in combination with selenomethionine were more effective in inhibiting the colony formation of Hela cells than when these cells were treated with these agents alone. Extracts of saffron (Crocus sativus) and selenite have previously been shown to inhibit the colony formation and nucleic acid synthesis by Hela cells in vitro. In the present study we examined the effects of saffron extract in combination with selenite on the colony formation and DNA and RNA synthesis in Hela cells. We found that the treatment of tumor Hela cells with saffron extract in combination with selenite increased the level of inhibition of the colony formation and nucleic acid synthesis in comparison with cells that were treated with only one of these agents. The inhibitory effect of saffron extract in combination with selenite was modified by intracellular sulfhydryl compounds. PMID:8922269

Abdullaev, F I; Gonzalez de Mejia, E

282

Effect of naturally occurring hydroxychavicol acetate on the cytokine production in T helper cells.  

PubMed

Naturally occurring phenolic compounds, such as chavicol analogues, have been shown to have potent antioxidant and anti-inflammatory activities. We have previously isolated two chavicol acetate analogues, acetoxychavicol acetate (ACA) and hydroxychavicol acetate (HCA) from the rhizomes of Alpinia galanga. Although the function of ACA has been studied in many systems, the function of HCA has yet to be systemically examined. In this study, we have comparably examined the functions of ACA and HCA on the cytokine production in Th cells. ACA exhibited potent antioxidant activity and increased cell apoptosis; therefore, cytokine production by Th cells was diminished. Although HCA had neither antioxidant activity nor pro-apoptotic function, it was shown to increase IL-2 production and attenuate IFNgamma expression in Th cells. In addition, we demonstrated that HCA suppressed T-bet expression, which is responsible for IL-2 suppression and IFNgamma induction in Th cells and inhibited T-bet-mediated Th1 cell differentiation. Therefore, we suggest that HCA may be beneficial as therapeutics for treating inflammatory immune disorders caused by extravagant activation of Th1-mediated immune responses. PMID:19208458

Min, Hyun Jung; Nam, Joo-Won; Yu, Eun Sun; Hong, Jeong-Ho; Seo, Eun-Kyoung; Hwang, Eun Sook

2009-02-07

283

Introduction to chemistry and applications in nature of mass independent isotope effects special feature.  

PubMed

Stable isotope ratio variations are regulated by physical and chemical laws. These rules depend on a relation with mass differences between isotopes. New classes of isotope variation effects that deviate from mass dependent laws, termed mass independent isotope effects, were discovered in 1983 and have a wide range of applications in basic chemistry and nature. In this special edition, new applications of these effects to physical chemistry, solar system origin models, terrestrial atmospheric and biogenic evolution, polar paleo climatology, snowball earth geology, and present day atmospheric sciences are presented. PMID:24167299

Thiemens, Mark H

2013-10-28

284

Measured intake and excretion patterns of naturally occurring 234U, 238U, and calcium in humans.  

PubMed

The normal dietary and fluid intake and urinary and fecal excretion of 234U and 238U were determined in humans under strictly controlled conditions in the Metabolic Research Ward at Hines Hospital. These values formed the basis of the metabolic balances of these uranium isotopes. The major pathway of 234U and of 238U excretion was via the intestine while the urinary 234U and 238U were very low, averaging 2% of the total excretion. The uranium balances were roughly in equilibrium. These data were used in combination with measurements of tissue concentrations of uranium from nonoccupationally exposed humans to calculate steady-state uptake factors for environmental exposure to uranium isotopes during baseline conditions of a normal dietary intake. PMID:2236501

Spencer, H; Osis, D; Fisenne, I M; Perry, P M; Harley, N H

1990-10-01

285

Characterization of calcium isotopes in natural and synthetic barite  

USGS Publications Warehouse

The mineral barite (BaSO4) accommodates calcium in its crystal lattice, providing an archive of Ca-isotopes in the highly stable sulfate mineral. Holocene marine (pelagic) barite samples from the major ocean basins are isotopically indistinguishable from each other (??44/40Ca = -2.01 ?? 0.15???) but are different from hydrothermal and cold seep barite samples (??44/40Ca = -4.13 to -2.72???). Laboratory precipitated (synthetic) barite samples are more depleted in the heavy Ca-isotopes than pelagic marine barite and span a range of Ca-isotope compositions, ??44/40Ca = -3.42 to -2.40???. Temperature, saturation state, a Ba2 + / a SO42 -, and aCa2+/aBa2+ each influence the fractionation of Ca-isotopes in synthetic barite; however, the fractionation in marine barite samples is not strongly related to any measured environmental parameter. First-principles lattice dynamical modeling predicts that at equilibrium Ca-substituted barite will have much lower 44Ca/40Ca than calcite, by -9??? at 0 ??C and -8??? at 25 ??C. Based on this model, none of the measured barite samples appear to be in isotopic equilibrium with their parent solutions, although as predicted they do record lower ??44/40Ca values than seawater and calcite. Kinetic fractionation processes therefore most likely control the extent of isotopic fractionation exhibited in barite. Potential fractionation mechanisms include factors influencing Ca2+ substitution for Ba2+ in barite (e.g. ionic strength and trace element concentration of the solution, competing complexation reactions, precipitation or growth rate, temperature, pressure, and saturation state) as well as nucleation and crystal growth rates. These factors should be considered when investigating controls on isotopic fractionation of Ca2+ and other elements in inorganic and biogenic minerals. ?? 2008 Elsevier Ltd.

Griffith, E. M.; Schauble, E. A.; Bullen, T. D.; Paytan, A.

2008-01-01

286

Distinguishing sources of base cations in irrigated and natural soils: evidence from strontium isotopes  

Microsoft Academic Search

Strontium isotope ratios (87Sr\\/86Sr) of soil solids, soil cation extracts, irrigation water and plant material are used to determine strontium and therefore cation sources and fluxes in irrigated and natural soil–plant systems. Strontium isotopes of soil solids from four soil profiles (two irrigated vineyard soils and two 'natural' profiles from nearby reserves) show large differences between soil horizons with depth.

Graham P. Green; Erick A. Bestland; G. Stewart Walker

2004-01-01

287

Estimated trichloroethene transformation rates due to naturally occurring biodegradation in a fractured-rock aquifer  

USGS Publications Warehouse

Rates of trichloroethene (TCE) mass transformed by naturally occurring biodegradation processes in a fractured rock aquifer underlying a former Naval Air Warfare Center (NAWC) site in West Trenton, New Jersey, were estimated. The methodology included (1) dividing the site into eight elements of equal size and vertically integrating observed concentrations of two daughter products of TCE biodegradation–cis-dichloroethene (cis-DCE) and chloride–using water chemistry data from a network of 88 observation wells; (2) summing the molar mass of cis-DCE, the first biodegradation product of TCE, to provide a probable underestimate of reductive biodegradation of TCE, (3) summing the molar mass of chloride, the final product of chlorinated ethene degradation, to provide a probable overestimate of overall biodegradation. Finally, lower and higher estimates of aquifer porosities and groundwater residence times were used to estimate a range of overall transformation rates. The highest TCE transformation rates estimated using this procedure for the combined overburden and bedrock aquifers was 945 kg/yr, and the lowest was 37 kg/yr. However, hydrologic considerations suggest that approximately 100 to 500 kg/yr is the probable range for overall TCE transformation rates in this system. Estimated rates of TCE transformation were much higher in shallow overburden sediments (approximately 100 to 500 kg/yr) than in the deeper bedrock aquifer (approximately 20 to 0.15 kg/yr), which reflects the higher porosity and higher contaminant mass present in the overburden. By way of comparison, pump-and-treat operations at the NAWC site are estimated to have removed between 1,073 and 1,565 kg/yr of TCE between 1996 and 2009.

Chapelle, Francis H.; Lacombe, Pierre J.; Bradley, Paul M.

2012-01-01

288

Residential Proximity to Naturally Occurring Asbestos and Mesothelioma Risk in California  

PubMed Central

Rationale: Little is known about environmental exposure to low levels of naturally occurring asbestos (NOA) and malignant mesothelioma (MM) risk. Objectives: To conduct a cancer registry-based case control study of residential proximity to NOA with MM in California. Methods: Incident MM cases (n = 2,908) aged 35 yr or more, diagnosed between 1988 and 1997, were selected from the California Cancer Registry and frequency matched to control subjects with pancreatic cancer (n = 2,908) by 5-yr age group and sex. Control subjects were selected by stratified random sampling from 28,123 incident pancreatic cancers in the same time period. We located 93.7% of subjects at the house or street level at initial diagnosis. Individual occupational exposure to asbestos was derived from the longest held occupation, available for 74% of MM cases and 63% of pancreatic cancers. Occupational exposure to asbestos was determined by a priori classification and confirmed by association with mesothelioma. Main Results: The adjusted odds ratios and 95% confidence interval for low, medium, and high probabilities of occupational exposures to asbestos were 1.71 (1.32–2.21), 2.51 (1.91–3.30), and 14.94 (8.37–26.67), respectively. Logistic regression analysis from a subset of 1,133 mesothelioma cases and 890 control subjects with pancreatic cancer showed that the odds of mesothelioma decreased approximately 6.3% for every 10 km farther from the nearest asbestos source, an odds ratio of 0.937 (95% confidence interval = 0.895–0.982), adjusted for age, sex, and occupational exposure to asbestos. Conclusions: These data support the hypothesis that residential proximity to NOA is significantly associated with increased risk of MM in California.

Pan, Xue-lei; Day, Howard W.; Wang, Wei; Beckett, Laurel A.; Schenker, Marc B.

2005-01-01

289

Modeling the pulsed light inactivation of microorganisms naturally occurring on vegetable substrates.  

PubMed

Pulsed light (PL) is a fast non-thermal method for microbial inactivation. This research studied the kinetics of PL inactivation of microorganisms naturally occurring in some vegetables. Iceberg lettuce, white cabbage and Julienne-style cut carrots were subjected to increasing PL fluences up to 12J/cm(2) in order to study its effect on aerobic mesophilic bacteria determined by plate count. Also, sample temperature increase was determined by infrared thermometry. Survivors' curves were adjusted to several models. No shoulder but tail was observed. The Weibull model showed good fitting performance of data. Results for lettuce were: goodness-of-fit parameter RMSE=0.2289, fluence for the first decimal reduction ?=0.98±0.80J/cm(2) and concavity parameter p=0.33±0.08. Results for cabbage were: RMSE=0.0725, ?=0.81±0.23J/cm(2) and p=0.30±0.02; and for carrot: RMSE=0.1235, ?=0.39±0.24J/cm(2) and p=0.23±0.03. For lettuce, a log-linear and tail model was also suitable. Validation of the Weibull model produced determination coefficients of 0.88-0.96 and slopes of 0.78-0.99. Heating was too low to contribute to inactivation. A single low-energy pulse was enough to achieve one log reduction, with an ultrafast treatment time of 0.5ms. While PL efficacy was found to be limited to high residual counts, the achievable inactivation level may be considered useful for shelf-life extension. PMID:21645816

Izquier, Adriana; Gómez-López, Vicente M

2011-04-07

290

Assessment of radiological hazards of naturally occurring radioactive materials in cement industry.  

PubMed

A study on the radiological hazard in Portland cement due to the presence of naturally occurring radioactive materials is being carried out. The Portland cement manufactured in the Islamabad/Rawalpindi region of Pakistan, intermediate products (clinker) and the various raw materials which compose the product have been analysed for (226)Ra, (232)Th and (40)K using a gamma spectrometry system with a N-type high-purity germanium detector of 80 % relative efficiency. From the measured gamma ray spectra, specific activities were determined. The mean values of the total specific activity of (226)Ra, (232)Th and (40)K are 34.2±11.9, 29.1±3.6 and 295.1±66.9 Bq kg(-1), respectively in Portland cement, 28.4±8.7, 11.3±1.7 and 63.1±17.3 Bq kg(-1), respectively in lime stone, 8.2±1.9, 16.2±3.9 and 187.7±53.2 Bq kg(-1), respectively in gypsum, 34.7±13.1, 41.2±6.7 and 187.6±17.2 Bq kg(-1), respectively in clay, 41.1±11.8, 39.3±6.9 and 195.1±29.2 Bq kg(-1), respectively in latrite and 51.1±18.2, 23.2±1.2 and 258.4±15.3 Bq kg(-1), respectively in clinker. The radium equivalent activities (Ra(eq)), external hazard index (H(ex)), internal hazard index (H(in)), absorbed dose rate in air (D) and annual effective dose rate (E(eff)) were also determined. The measured activity concentrations for these radio nuclides and radiological indices were compared with the reported national and international data. All these measured values are comparable with the worldwide data reported in UNSCEAR publications. PMID:22355168

Aslam, Muhammad; Gul, Rahmat; Ara, Tauseef; Hussain, Manzur

2012-02-20

291

Polyporus tenuiculus: a new naturally occurring mushroom that can be industrially cultivated on agricultural waste.  

PubMed

Polyporus tenuiculus is a naturally occurring species from Central and South America that is consumed by different ethnic groups in the region. To determine the optimal conditions for fruiting body production, two strains were assayed on wheat straw and sawdust with or without supplements. Sixty days of incubation at 25 degrees C were needed to produce a solid block. The highest yield was obtained with strain ICFC 383/00 grown on supplemented willow sawdust. In a second experiment the strain ICFC 383/00 and different supplements were used to improve the biological efficiency (BE) and to determine the quality traits and its biodegradation capacity. The highest yields were obtained on sawdust with 25% of supplements reaching 82.7% of BE. Supplements raised the number of flushes, generally from four to five, contributing to increased yields. The type of substrate had a significant effect on fruiting body diameters of P. tenuiculus, and the largest mushrooms were harvested on supplemented substrate with the highest BE coinciding with the highest dry matter loss in substrates. P. tenuiculus showed a capacity to degrade sawdust, causing a decrease of 67.2-74.5% in cellulose, 80.4-85.7% in hemicellulose, and 60.6-66.2% in lignin content at the end of the cultivation cycle. The decrease in hemicellulose was relatively greater than that of cellulose and lignin on supplemented substrates. This is the first report of the cultivation of P. tenuiculus on lignocellulosic waste, and it is a promising species both for commercial production and for its potential use in the degradation of other biowastes. PMID:19212788

Omarini, Alejandra; Lechner, Bernardo E; Albertó, Edgardo

2009-02-11

292

Diversity of Opines and Opine-Catabolizing Bacteria Isolated from Naturally Occurring Crown Gall Tumors  

PubMed Central

The diversity of opines from 43 naturally occurring crown gall tumors on several plant species was analyzed for the presence of agropine, chrysopine, iminodiacid, an unidentified leucinopine-like iminodiacid (IDA-B), mannopine, octopine, nopaline, DL- and LL-succinamopine, leucinopine and heliopine. Opine utilization patterns of agrobacteria and fluorescent pseudomonads resident in a tumor were then analyzed and compared for agreement with the opine isolated from that tumor. Nopaline was the most common opine found and was detected in tumors from cherry, blackberry, grape, and plum. Octopine was not found, although octopine-catabolizing bacteria were isolated from several tumors. A new, previously undescribed iminodiacid of the succinamopine-leucinopine type (provisionally designated IDA-B) was isolated from tumors of wild blackberry. Field tumors from apple, blueberry and grape yielded no detectable opines, even though opine-utilizing bacteria were present. Bacterial isolates from plum and cherry showed the best correspondence between the opine in tumors (nopaline) and the presence of bacteria that catabolized that opine. However, several unusual opine catabolic combinations were identified, including isolates that catabolized a variety of opines but were nonpathogenic. More variability was observed among isolates from field tumors on the remaining plant species. We isolated novel mannopine-nopaline type agrobacteria from field tumors of cherry, plum and blackberry that induced tumors containing either mannopine (plus agropine) or nopaline, but not both. Epidemiologically, the galled plants from an area were not of clonal origin (same Ti plasmid), indicating that the field tumors from a small area were incited by more than one type of Ti plasmid.

Moore, L. W.; Chilton, W. S.; Canfield, M. L.

1997-01-01

293

Determination of naturally occurring MTBE biodegradation by analysing metabolites and biodegradation by-products  

NASA Astrophysics Data System (ADS)

Methyl tert-butyl ether (MTBE) is one of the main additives in gasoline. Its degradation is known to be difficult in natural environments. In this study, significant MTBE degradation is demonstrated at a contaminated site in Leuna (eastern Germany). Since the extent of the plume appeared to be constant over the last 5 years, an extended study was performed to elucidate the degradation processes. Special attention was paid to the production, accumulation and degradation of metabolites and by-products. Groundwater samples from 105 monitoring wells were used to measure 20 different substances. During the degradation process, several intermediates such as tert-butyl alcohol (TBA), tert-butyl formate, formate and lactate were produced. However, the potentially carcinogenic by-product methacrylate was not detected in several hundred samples. At the Leuna site, MTBE degradation occurred under microaerobic conditions. In contrast to hydrocarbons and BTEX, there was no evidence for anaerobic MTBE degradation. Among the degradation products, TBA was found to be a useful intermediate to identify MTBE degradation, at least under microaerobic conditions. TBA accumulation was strongly correlated to MTBE degradation according to the kinetic properties of both degradation processes. Since maximum degradation rates (vmax) and km values were higher for MTBE (vmax = 2.3 mg/l/d and km = 3.2 mg/l) than for TBA (vmax = 1.35 mg/l/d and km = 0.05 mg/l), TBA significantly accumulated as an intermediate by-product. The field results were supported by bench scale model aquifer experiments.

Martienssen, Marion; Fabritius, Holger; Kukla, Stefan; Balcke, Gerd U.; Hasselwander, Eyk; Schirmer, Mario

2006-09-01

294

Removal of arsenite and arsenate using hydrous ferric oxide incorporated into naturally occurring porous diatomite.  

PubMed

In this study, a simplified and effective method was tried to immobilize iron oxide onto a naturally occurring porous diatomite. Experimental resultsfor several physicochemical properties and arsenic edges revealed that iron oxide incorporated into diatomite was amorphous hydrous ferric oxide (HFO). Sorption trends of Fe (25%)-diatomite for both arsenite and arsenate were similar to those of HFO, reported by Dixit and Hering (Environ. Sci. Technol. 2003, 37, 4182-4189). The pH at which arsenite and arsenate are equally sorbed was 7.5, which corresponds to the value reported for HFO. Judging from the number of moles of iron incorporated into diatomite, the arsenic sorption capacities of Fe (25%)-diatomite were comparable to or higher than those of the reference HFO. Furthermore, the surface complexation modeling showed that the constants of [triple bond]SHAsO4- or [triple bond]SAsO4(2-) species for Fe (25%)-diatomite were larger than those reference values for HFO or goethite. Larger differences in constants of arsenate surface species might be attributed to aluminum hydroxyl ([triple bond]Al-OH) groups that can work better for arsenate removal. The pH-controlled differential column batch reactor (DCBR) and small-scale column tests demonstrated that Fe (25%)-diatomite had high sorption speeds and high sorption capacities compared to those of a conventional sorbent (AAFS-50) that is known to be the first preference for arsenic removal performance in Bangladesh. These results could be explained by the fact that Fe (25%)-diatomite contained well-dispersed HFO having a great affinity for arsenic species and well-developed macropores as shown by scanning electron microscopy (SEM) and pore size distribution (PSD) analyses. PMID:16568781

Jang, Min; Min, Soo-Hong; Kim, Tak-Hyun; Park, Jae Kwang

2006-03-01

295

Endogenous relaxin is a naturally occurring modulator of experimental renal tubulointerstitial fibrosis.  

PubMed

Relaxin is a naturally occurring regulator of collagen turnover. In this study, we determined the role of endogenous relaxin in the pathogenesis of primary tubulointerstitial fibrosis after unilateral ureteric obstruction (UUO). Four- to 6-wk-old relaxin (RLX) gene-knockout (RLX(-/-)) and age-matched wild-type (RLX(+/+)) mice, with equivalent baseline collagen levels, were subjected to UUO. Obstructed and contralateral kidneys were collected at d 0, 3, and 10 after surgery and analyzed for changes in inflammatory and fibrosis-related markers. UUO was associated with a progressive increase in fibrosis in all obstructed, but not contralateral kidneys. The increase in total collagen (hydroxyproline analysis) was associated with more alpha-smooth muscle actin (alpha-SMA) staining (myofibroblasts) and interstitial collagen sub-types (SDS-PAGE; types I, III, and V), whereas gelatin zymography demonstrated increased expression of matrix metalloproteinase-2 after surgery. By d 10 after UUO, there was a 5-fold decrease in RLX mRNA expression (quantitative RT-PCR) in RLX(+/+) animals. Total collagen and alpha-SMA expression were significantly greater in the obstructed kidneys of RLX(-/-) mice 3 d after UUO (both P < 0.05 vs. RLX(+/+) D3 after UUO), but comparable to that in RLX(+/+) animals 10 d after UUO. Administration of recombinant H2 relaxin to RLX(-/-) mice 4 d before UUO ameliorated the increase in collagen and alpha-SMA expression (both P < 0.05 vs. untreated RLX(-/-) mice) by d 3 after UUO. Expression of monocyte chemoattractant protein-1 and macrophage infiltration (inflammation) in addition to that of matrix metalloproteinases was unaffected by genotype after UUO. These combined data demonstrate that endogenous RLX acts as a modulating factor in tubulointerstitial fibrosis, a hallmark of progressive renal disease. This is likely to be via direct effects on renal myofibroblast function. PMID:17095590

Hewitson, Tim D; Mookerjee, Ishanee; Masterson, Rosemary; Zhao, Chongxin; Tregear, Geoffrey W; Becker, Gavin J; Samuel, Chrishan S

2006-11-09

296

The isotopic effects of electron transfer: An explanation for Fe isotope fractionation in nature  

Microsoft Academic Search

Isotope fractionation of electroplated Fe was measured as a function of applied electrochemical potential. As plating voltage was varied from ?0.9 V to 2.0 V, the isotopic signature of the electroplated iron became depleted in heavy Fe, with ?56Fe values (relative to IRMM-14) ranging from ?0.18(±0.02) to ?2.290(±0.006) ‰, and corresponding ?57Fe values of ?0.247(±0.014) and ?3.354(±0.019) ‰. This study

Abby Kavner; François Bonet; Anat Shahar; Justin Simon; Edward Young

2005-01-01

297

Natural mass-dependent variations in the isotopic composition of molybdenum  

NASA Astrophysics Data System (ADS)

We present the first observations of natural mass-dependent fractionation of the isotopic composition of molybdenum (Mo), using multi-collector inductively coupled plasma mass spectrometry. Variations in the isotopic composition of Mo are reported as ? 97/95Mo (=(( 97Mo/ 95Mo) sample/( 97Mo/ 95Mo) standard-1)×1000‰). External analytical precision of ? 97/95Mo is <±0.25‰ (2?) on natural samples. Our data demonstrate a clear offset of >1‰ between sediments deposited under anoxic conditions (? 97/95Mo=+1.02 to +1.52‰ relative to our in-house standard) and ferromanganese nodules (? 97/95Mo=-0.63 to -0.42‰). ? 97/95Mo of Pacific Ocean seawater (? 97/95Mo=+1.48‰) lies within the range of values for anoxic sediments, closest to modern Black Sea anoxic sediments. Molybdenites from continental ore deposits have intermediate ? 97/95Mo ranging from -0.26 to +0.09‰. Variations in the abundances of 92Mo, 95Mo, 96Mo, 97Mo and 98Mo are consistent with mass-dependent fractionation. A sporadic unidentified interference occurs at mass 94 and 100Mo is not measured. We hypothesize that the ? 97/95Mo offset between anoxic sediments and ferromanganese nodules results from Mo isotope fractionation during inefficient scavenging of Mo from seawater by Mn oxides under oxic conditions. The similarity in ? 97/95Mo of anoxic sediments and seawater is consistent with the very efficient removal of Mo from seawater under anoxic conditions in the presence of H 2S. The data can be interpreted in terms of a steady-state mass balance between the Mo flux into the oceans from the continents and the Mo flux out of the oceans into oxic and anoxic sediments. Such an interpretation is quantitatively consistent with existing estimates of the removal fluxes of Mo to anoxic and oxic sediments. These findings suggest that ? 97/95Mo in seawater may co-vary with changes in the relative proportions of anoxic and oxic sedimentation in the oceans, and that this variation may be recorded in ? 97/95Mo of anoxic sediments. Hence, the Mo isotope system may be useful in paleoredox investigations.

Barling, J.; Arnold, G. L.; Anbar, A. D.

2001-12-01

298

Naturally Occurring Radionuclides of Ash Produced by Coal Combustion. The Case of the Kardia Mine in Northern Greece  

Microsoft Academic Search

West Macedonia Lignite Center (WMLC), located in Northwest Greece, releases into the atmosphere about 21,400 tons\\/year of fly ash through the stacks of four coal fired plants. The lignite ash contains naturally occurring radionuclides, which are deposited on the WMLC basin. This work investigates the natural radioactivity of twenty six ash samples, laboratory produced from combustion of lignite, which was

M. Fotakis; L. Tsikritzis; N. Tzimkas; N. Kolovos; R. Tsikritzi

2008-01-01

299

Investigation of Naturally Occurring Radio Nuclides in Shir-kuh Granites  

NASA Astrophysics Data System (ADS)

One of the principle natural radiation resources is Granite which can be dangerous for human because of its radiations. Based on this fact, in this research we attempt to specify the activity amount of these natural radio nuclides, existing in Shir-kuh Granite of Yazd state. To specify the activity amount of this natural radio nuclides, it has been applied the measurement method of Gamma spectroscopy using high purity Germanium (HPGe) detector.

Mazarei, Mohammad Mehdi; Zarei, Mojtaba

2011-12-01

300

Investigation of Naturally Occurring Radio Nuclides in Shir-kuh Granites  

SciTech Connect

One of the principle natural radiation resources is Granite which can be dangerous for human because of its radiations. Based on this fact, in this research we attempt to specify the activity amount of these natural radio nuclides, existing in Shir-kuh Granite of Yazd state. To specify the activity amount of this natural radio nuclides, it has been applied the measurement method of Gamma spectroscopy using high purity Germanium (HPGe) detector.

Mazarei, Mohammad Mehdi; Zarei, Mojtaba [Department of Science, Bushehr Branch, Islamic Azad University, City of Aalishahr, Bushehr Province, Iran P.O.Box: 7519619555 (Iran, Islamic Republic of)

2011-12-26

301

Some natural variations in the relative abundance of copper isotopes  

USGS Publications Warehouse

The relative isotopic abundance of copper has been measured in a number of minerals and a few plant materials. Suites of samples from Michigan and the Colorado Plateau have been examined in more detail to determine if local variations due to isotopic exchange or diffusion could be found. The relative isotopic abundance of copper in specimens from several other localities was also determined. The variations noted were small but in some cases were felt to be significant because they were larger than the experimental error (0??1 per cent in the ratio). A total spread of -1 to +8 parts per mil compared to the standard was found in the specimens tested. ?? 1958.

Walker, E. C.; Cuttitta, F.; Senftle, F. E.

1958-01-01

302

Elevated Bacterial Abundance in Laboratory-Grown and Naturally Occurring Frost Flowers Under Late Winter Conditions  

NASA Astrophysics Data System (ADS)

Sea ice has been identified as an important microbial habitat, with bacteria and other microbes concentrated in the brine inclusions between ice crystals. Frost flowers, thought to draw brine from underlying sea ice, have not been characterized from a microbial standpoint. To test whether frost flowers serve as an upward vector of bacteria contained within sea ice brines we grew frost flowers in a freezer laboratory (air temperature of -21°C) from saline water spiked with the mesophilic (and thus passive under experimental conditions) bacterium Halomonas pacifica. Salinity of melted samples was measured and bacterial abundance determined by epifluorescent microscopy. Bacterial counts scaled to ice-melt volume averaged 2.82 x 106 ml-1 for frost flowers, compared to 9.47 x 105 ml-1 for underlying ice (3 x higher). Bacterial counts also correlated significantly with salinity (maximum value of 62.5 psu) for frost flowers, brine skim, and ice (df = 17, r = 0.59, p < 0.0001). Segregation coefficients were calculated to describe the efficiency of transport of both cells and salt from the starting solution into frost flowers. From these coefficients an enrichment index was calculated to test for bacterial concentration into frost flowers at a different rate than salt. Analysis with a Student’s T-test (df = 24, t = 0.306, p = .76) indicated that cells and salt were not transported into frost flowers with a significantly different efficiency. To test these findings in the field we then collected frost flowers (and related samples) from new sea ice near Barrow, Alaska in April 2009. Bacterial counts were significantly elevated (again, a 3-fold increase) in natural frost flowers (mean = 2.73 x 105 ml-1) compared to underlying sea ice (mean = 8.46 x 104 cells ml-1). For all field samples collected (frost flowers, underlying brine skim and sea ice, as well as snow), bacterial abundance correlated significantly with salinity (maximum value 124 psu, df = 40, r = 0.60, p < 0.0001). The presence of elevated numbers of bacteria in frost flowers may have implications for the previously observed chemical reactions that take place in them, especially if microbial activity can be shown to occur in this unique low temperature, low water activity microbial habitat.

Bowman, J. S.; Deming, J. W.

2009-12-01

303

Increased carbon uptake in marine sediment enabled by naturally occurring electrical conductors  

NASA Astrophysics Data System (ADS)

Reduction-oxidation (redox) gradients are common across marine sediment-water interfaces and result from microbially-mediated reactions such as the oxidation of organic matter coupled to reduction of electron acceptors. Most microbes living in sediments do not have direct access to oxygen in their immediate environment, however it has recently been shown that sulfide-oxidizing microbes may employ extracellular electron transfer (EET) to couple the oxidation of sulfide in the anoxic zone to reduction of oxygen at the sediment-water interface located several centimeters away. However, no mechanisms for this observed phenomenon have been validated. Accordingly, we tested the hypothesis that conductive minerals in marine sediment (specifically pyrite) can couple spatially separated redox reactions such as anaerobic respiration and oxygen reduction. Marine sediment was amended with naturally occurring pyrite in varying concentrations (0, 2, 10 and 50 weight-percent) and then incubated with 10 ?M 13C-labeled acetate. After six hours, the treatments with the greatest amount of added pyrite showed the greatest incorporation of acetate from the labeled pool. The fraction of labeled acetate incorporation more than doubled in the 10 and 50 weight-percent treatments compared to the control sediment. We also designed a circuit to investigate the electrical conductivity of the sediment treatments as a function of added pyrite. A potentiostat was used to establish a known voltage across a sediment column and current was measured. Resistance (the inverse of conductance) was calculated from a linear fit of current data over a range of voltages ranging from 0.5 to 1.0 V. The treatments with added pyrite had lower resistance than background sediment, with the lowest resistance corresponding to the 50% pyrite treatment. We also examined the effect of varying pyrite content on microbial community composition using massively parallel 16S rRNA sequencing. Microbial community analyses reveal that the majority of microbes in the sediment belong to the deltaproteobacteria or gammaproteobacteria classes, which have been previously implicated in EET in laboratory and field-based bioelectrochemical studies. These data force us to reconsider the role of EET and conductive minerals in organic carbon cycling -particularly in metaliferous sediments- and suggest that EET-enabled anaerobic metabolism may represent a significant contribution to marine carbon cycling.

Nielsen, M. E.; Cahoon, D. P.; Girguis, P. R.

2011-12-01

304

Glargine insulin for treatment of naturally occurring diabetes mellitus in dogs.  

PubMed

Objective-To evaluate the effects of twice-daily glargine insulin administration in dogs with diabetes mellitus. Design-Open-label, prospective clinical trial. Animals-10 dogs with naturally occurring diabetes mellitus. Procedures-Dogs with poorly regulated or newly diagnosed diabetes mellitus were enrolled if their owners agreed to return them to the hospital at 1- to 3-week intervals for 4 follow-up visits. During each follow-up visit, blood glucose concentrations were measured every 2 hours for at least 10 hours after feeding a diet high in insoluble fiber and after administration of glargine insulin (time 0). The initial glargine insulin dosage was 0.5 U/kg (0.23 U/lb) SC twice daily. Results-All dogs had well-regulated diabetes mellitus at a mean ± SD of 38 ± 14 days (median, 43 days; range, 7 to 55 days) following study enrollment. At the time diabetes mellitus was well regulated, mean glargine insulin dosage was 0.5 ± 0.15 U/kg (0.23 ± 0.068 U/lb; median, 0.5 U/kg; range, 0.32 to 0.67 U/kg [0.15 to 0.30 U/lb]) twice daily, and 3 dogs were receiving a dosage < 0.4 U/kg (0.18 U/lb). In dogs with well-regulated diabetes mellitus, the mean minimum blood glucose concentration (163 ± 89 mg/dL; 95% confidence interval, 100 to 227 mg/dL) was detected 2 hours after administration of glargine insulin and the mean maximum blood glucose concentration (230 ± 95 mg/dL; 95% confidence interval, 64 to 323 mg/dL) was detected 12 hours after administration of glargine insulin. There was no significant difference between mean minimum and mean maximum blood glucose concentrations nor were there significant differences between blood glucose concentrations measured at other time points. Blood glucose concentration < 80 mg/dL was measured at least once in 7 of 10 dogs. Conclusions and Clinical Relevance-Results of the present study suggested that, in diabetic dogs fed a diet high in insoluble fiber, glargine insulin is a peakless insulin that does not induce a distinct blood glucose concentration nadir. For glargine insulin, 0.3 U/kg (0.136 U/lb) SC twice daily is recommended as an initial dosage. PMID:24094263

Hess, Rebecka S; Drobatz, Kenneth J

2013-10-15

305

Mechanisms of action of naturally occurring antibodies against ?-amyloid on microglia  

PubMed Central

Background Naturally occurring autoantibodies against amyloid-? (nAbs-A?) have been shown to exert beneficial effects on transgenic Alzheimer’s disease (AD) animals in vivo and on primary neurons in vitro. Not much is known about their effect on microglial cells. Our aim was to investigate the effect of nAbs-A? on amyloid-? (A?)-treated microglial cells in vitro with respect to cell viability, stress pathways, cytokine production and phagocytotic abilities and whether these effects can be conveyed to neurons. Methods Primary microglial cells isolated from Swiss Webster mouse mesencephalons on embryonic day 13.5 were pretreated with nAbs-A? and then treated with A? oligomers. After 3 hours, phagocytosis as well as western blot analysis were evaluated to measure the amount of phagocytized A?. Cell viability was analyzed using an MTT assay 24 hours after treatment. Pro-inflammatory cytokines in the supernatants were analyzed with ELISAs and then we treated primary neuronal cells with these conditioned microglia supernatants. Twenty-four hours later we did a MTT assay of the treated neurons. We further investigated the effect of a single nAbs-A? administration on Tg2576 mice in vivo. Results Upon co-administration of A? and nAbs-A? no change in microglia viability was observed. However, there was an increase in phosphorylated p38 protein level, an increase in the pro-inflammatory cytokines TNF-? and IL-6 and an increase in A? uptake by microglial cells. Treatment of primary neurons with conditioned microglia medium led to a 10% improvement in cell viability when nAbs-A? were co-administered compared to A?-treated cells alone. We were unable to detect changes in cytokine production in brain lysates of Tg2576 mice. Conclusions We provide evidence on the mechanism of action of nAbs-A? on microglia in vitro. Interestingly, our in vivo data indicate that nAbs-A? administration should be considered as a therapeutic strategy in AD, since there is no inflammatory reaction.

2013-01-01

306

Magnesium isotope fractionation by chemical diffusion in natural settings and in laboratory analogues  

NASA Astrophysics Data System (ADS)

Laboratory experiments are used to document isotopic fractionation of magnesium by chemical diffusion in a silicate melt and the results compared to the magnesium isotopic composition across contacts between igneous rocks of different composition in natural settings. The natural samples are from transects from felsic to mafic rocks at Vinal Cove in the Vinalhaven Intrusive Complex, Maine and from the Aztec Wash pluton in Nevada. Two laboratory diffusion couples made by juxtaposing melts made from powders of the felsic and mafic compositions sampled at Vinal Cove were annealed at about 1500 °C for 22.5 and 10 h, respectively. The transport of magnesium in the diffusion couples resulted in easily measured magnesium isotopic fractionations at the interface (?26Mg˜1.5‰). These isotopic fractionations provide a distinctive isotopic "fingerprint" that we use to determine whether chemical gradients in natural settings where melts of different composition were juxtaposed were due to chemical diffusion. The magnesium isotopic fractionation along one profile at Vinal Cove is exactly what one would expect based on the fractionations found in the laboratory experiments. This is an important result in that it shows that the isotope fractionation by chemical diffusion found in highly controlled laboratory experiments can be found in a natural setting. This correspondence implies that chemical diffusion was the dominant process responsible for the transport of magnesium across this particular contact at Vinal Cove. A second Vinal Cove profile has a very similar gradient in magnesium concentration but with significantly less magnesium isotopic fractionation than expected. This suggests that mass transport at this location was only partly by diffusion and that some other mass transport mechanism such as mechanical mixing must have also played a role. The magnesium isotopic composition of samples from Aztec Wash shows no resolvable isotopic fractionation across the contact between the mafic and felsic rocks. The different degrees of magnesium isotopic fractionation associated with otherwise similar composition gradients in natural settings show that kinetic isotope fractionations provide a key discriminator for establishing whether or not molecular diffusion was the process responsible for an observed elemental gradient. In the one case of a contact at Vinal Cove where we are confident that the magnesium elemental and isotopic gradients were produced by diffusion, we deduced a cooling rate of about 1.5 °C per day.

Chopra, Rahul; Richter, Frank M.; Bruce Watson, E.; Scullard, Christian R.

2012-07-01

307

Assessing Interactions of Organic Compounds during Biodegradation of Complex Waste Mixtures by Naturally Occurring Bacterial Assemblages.  

National Technical Information Service (NTIS)

Selected organic chemicals were tested to determine the minimum concentrations at which complete inhibition of microbial degradative processes occurred. Complete inhibition did not occur at less than 2 g/L phenol, 10 g/L toluene or n-butanol, and 100 g/L ...

H. M. Hwang R. E. Hodson D. L. Lewis

1989-01-01

308

High Diversity of the Fungal Community Structure in Naturally-Occurring Ophiocordyceps sinensis  

Microsoft Academic Search

BackgroundOphiocordyceps sinensis (syn. Cordyceps sinensis), which is a parasite of caterpillars and is endemic to alpine regions on the Tibetan Plateau, is one of the most valuable medicinal fungi in the world. “Natural O. sinensis specimens” harbor various other fungi. Several of these other fungi that have been isolated from natural O. sinensis specimens have similar chemical components and\\/or pharmaceutical

Yongjie Zhang; Shu Zhang; Mu Wang; Fengyan Bai; Xingzhong Liu; Alexander Idnurm

2010-01-01

309

Naturally-Occurring Radionuclides In Drinking Water From Surface And Groundwater Reservoirs  

SciTech Connect

Radioactivity in water for human consumption is under closer scrutiny than ever before and many countries adopted guideline values based on total alpha and total beta activity measurements. Although most waters from surface circulation meet these guidelines, it is frequently found that groundwater exceed guideline values. Results of water analyses by alpha spectrometry clarified that the main radionuclides present are from the uranium decay series, such as uranium isotopes, radium ({sup 226}Ra), radon ({sup 222}Rn), and also {sup 210}Pb and {sup 210}Po. Occasionally, groundwater displayed {sup 226}Ra concentrations higher than 1 Bq L{sup -1} and {sup 222}Rn concentrations above 1000 Bq L{sup -1}. Nevertheless, lack of conformity of these waters with guidelines adopted, generally, is not due to anthropogenic inputs.

Carvalho, F. P.; Madruga, M. J.; Oliveira, J. M.; Lopes, I.; Ferrador, G.; Sequeira, M. M. [Nuclear and Technological Institute (ITN) Department of Radiological Protection and Nuclear Safety E.N. 10, 2686-953 Sacavem (Portugal)

2008-08-07

310

Naturally-Occurring Radionuclides In Drinking Water From Surface And Groundwater Reservoirs  

NASA Astrophysics Data System (ADS)

Radioactivity in water for human consumption is under closer scrutiny than ever before and many countries adopted guideline values based on total alpha and total beta activity measurements. Although most waters from surface circulation meet these guidelines, it is frequently found that groundwater exceed guideline values. Results of water analyses by alpha spectrometry clarified that the main radionuclides present are from the uranium decay series, such as uranium isotopes, radium (226Ra), radon (222Rn), and also 210Pb and 210Po. Occasionally, groundwater displayed 226Ra concentrations higher than 1 Bq L-1 and 222Rn concentrations above 1000 Bq L-1. Nevertheless, lack of conformity of these waters with guidelines adopted, generally, is not due to anthropogenic inputs.

Carvalho, F. P.; Madruga, M. J.; Oliveira, J. M.; Lopes, I.; Ferrador, G.; Sequeira, M. M.

2008-08-01

311

APPLICATIONS OF ENVIRONMENTAL ISOTOPES FOR WATERSHED INVESTIGATIONS  

EPA Science Inventory

Environmental isotopes include naturally-occurring nuclides that can be applied as tracers within watersheds (Sidle, 1998). Recent advances in mass spectroscopy may supplant many traditional and costly hydrometric techniques. It is now possible, for example, to utilize isotopes a...

312

Review of research on impacts to biota of discharges of naturally occurring radionuclides in produced water to the marine environment.  

PubMed

Produced water has been described as the largest volume waste stream in the exploration and production process of oil and gas. It is accompanied by discharges of naturally occurring radionuclides raising concerns over the potential radiological impacts of produced water on marine biota. In the Northern European marine environment, radioactivity in produced water has received substantial attention owing to the OSPAR Radioactive Substances Strategy which aims at achieving 'concentrations in the environment near background values for naturally occurring radioactive substances'. This review provides an overview of published research on the impacts to biota from naturally occurring radionuclides discharged in produced water by the offshore oil and gas industry. In addition to summarising studies and data that deal directly with the issue of dose and effect, the review also considers studies related to the impact of added chemicals on the fate of discharged radionuclides. The review clearly illustrates that only a limited number of studies have investigated possible impacts on biota from naturally occurring radionuclides present in produced water. Hence, although these studies indicate that the risk to the environment from naturally occurring radionuclides discharged in produced water is negligible, the substantial uncertainties involved in the assessments of impact make it difficult to be conclusive. With regard to the complexity involved in the problem under consideration there is a pressing need to supplement existing data and acquire new knowledge. Finally, the present work identifies some knowledge gaps to indicate future research requirements. PMID:23022586

Hosseini, Ali; Brown, Justin E; Gwynn, Justin P; Dowdall, Mark

2012-09-26

313

Investigating microbial carbon cycling using natural abundance isotope analysis of PLFA  

Microsoft Academic Search

Understanding microbial carbon sources and cycling is fundamental to our conceptualization of microbial ecosystems and their role in biogeochemical cycling in natural systems. Achieving this understanding requires application of a wide range of approaches. Natural abundance isotope analysis of individual compounds, particularly cellular components such as Phospholipids Fatty Acids (PLFA) can provide insights into the carbon sources and metabolic activities

G. G. Slater; A. Brady; B. Cowie

2008-01-01

314

Fate and bioaccumulation of soil-associated low-level naturally occurring radioactivity following disposal into a marine ecosystem. Final report  

SciTech Connect

The fate of radium (Ra) and other naturally occurring uranium-series isotopes associated with soils disposed in seawater was examined using the Marine Ecosystem Research Laboratory (MERL) controlled marine ecosystems. Thirty-seven kilograms of a soil containing approximately 400 pCi Ra-226/g from an inactive uranium ore processing plant site in Middlesex, New Jersey, were added to each of two mesocosms over five days in mid-September 1984. Radionuclide activity in these and two control mesocosms was observed for three months after the soil additions. Radioactivity in the soil appeared to be confined to discrete soil particles rather than being distributed equally on the soil particles, suggesting the source of the radioactivity was remnant ore particles.

Hunt, C.D.

1986-10-01

315

Rare gas isotopic compositions in natural gases of Japan  

Microsoft Academic Search

Isotopic and elemental compositions of rare gases in various types of gas samples collected in the Japanese Islands were investigated. Excess 3He was found in most samples. Many samples showed a regionally uniform high 3He\\/4He ratio of about 7 times the atmospheric ratio. The He concentrations varied from 0.6 to 1800 ppm, and they were low in CO2-rich gases and

Keisuke Nagao; Nobuo Takaoka; Osamu Matsubayashi

1981-01-01

316

RESTORATION OF MUNICIPAL DRINKING WATER SUPPLY WELLS IMPACTED BY NATURALLY OCCURRING ARSENIC  

EPA Science Inventory

Studies have indicated that arsenic concentrations greater than the newly proposed U.S. Environmental Protection Agency (EPA) maximum contaminant level (MCL) of 10 micrograms per liter (ug/L) occur in specific parts of numerous aquifers around the United States. One such aquifer...

317

Potential use of naturally occurring sulphuric acid to beneficiate poorly soluble phosphate from Eppawala, Sri Lanka  

Microsoft Academic Search

A 29 000 yr old high-sulphur peat deposit occurs in the western district of Colombo, Sri Lanka. This permanently submerged deposit has several pyrite-rich layers in 8 to 10 m sequences and is connected to the open ocean. Sea water intrudes to the peat deposit during tidal movements. Villagers have excavated the peat to form islands which serve as foundations

Kapila Dahanayake; Atula Senaratne; S. M. N. D. Subasinghe; A. Liyanaarachchi

1991-01-01

318

Vitamin B 12 production and depletion in a naturally occurring eutrophic lake.  

PubMed

The distribution of vitamin B(12) within Upper Klamath Lake was surveyed at approximately monthly intervals during a period from September 1968 to November 1969. High concentrations (up to 1.8 mug/g of dry sediment) characteristically occurred at the water-sediment interface, with a sharp decline below this area. A heavy bloom of Aphanizomenon flos-aquae occurred from the latter part of May through October 1969. B(12) concentrations of the uppermost sediments, from all but one sampling site, increased gradually through the bloom, followed by a drastic increase during the die-off period. B(12) is probably not a limiting factor for primary productivity, since sufficient levels of this vitamin were found to occur throughout the year. Of 42 cultures isolated from Upper Klamath Lake water and sediments, 20 were found capable of producing 50 pg or more of B(12)/ml of medium. Phytoplankton samples were found to contain up to 5 mug of B(12)/g of dry material. Degradation of B(12) occurred in sterilized as well as fresh sediment samples. PMID:4622828

Gillespie, P A; Morita, R Y

1972-02-01

319

Spectroscopic study of major components of dissolved organic matter naturally occurring in water  

Microsoft Academic Search

Natural organic compounds are present in significant concentration in all types of water. The spectroscopic study of dissolved organic matter and its major components is important for applications of lidar remote sensing techniques for water quality measurements. In this paper, fluorescence emission and excitation spectra, as well as absorption spectra for commercially available analogues of major components of gelbstoff are

Svetlana V. Patsayeva; Rainer Reuter

1995-01-01

320

NATURAL OCCURANCE OF XYLELLA FASTIDIOSA IN A COMMERCIAL NURSERY IN MARYLAND  

Technology Transfer Automated Retrieval System (TEKTRAN)

Since Xylella fastidiosa is an important plant pathogen in the landscape nursery trade, a survey was conducted in 2003 and 2004 in a commercial wholesale and production nursery in Maryland to determine the natural occurrence of X. fastidiosa in nursery plants and surrounding vegetation using enzyme-...

321

Potential involvement of Neospora caninum in naturally occurring ovine abortions in New Zealand  

Microsoft Academic Search

Neospora caninum is an obligate intracellular parasite and is recognised as the leading cause of bovine abortion worldwide. Natural infection with N. caninum has been described in sheep but it has generally not been regarded as a significant cause of abortion. Recently, there have been several New Zealand cases of foetal abortions where N. caninum was detected which strongly suggested

L. Howe; M. G. Collett; R. S. Pattison; J. Marshall; D. M. West; W. E. Pomroy

322

Algal products as naturally occurring modulators for the multidrug resistance (MDR) transporter  

Microsoft Academic Search

Extracts of various algae show modulating activity of the multidrug resistance (MDR) transporter in the mussel Mytilus californianus. Mytilus californianus is a filter feeder that removes seaweed particulates, phytoplankton and their byproducts from the water. The gills of Mytilus californianus express high MDR titer and activity possibly to provide protection from natural toxins in the diet. To test this hypothesis,

N. Eufemia; S. Girshick; D. Epel

2000-01-01

323

Temperature-composition relationships between naturally occurring augite, pigeonite, and orthopyroxene at one bar pressure  

Microsoft Academic Search

Natural orthopyroxene crystals containing augite exsolution lamellae were heated at one bar and controlled oxygen fugacity to determine the temperature at which orthopyroxene + augite first react to form pigeonite + melt. Pigeonite was detected by X-ray precession pho- tography. The reaction to form pigeonite is initiated at the orthopyroxene-augite boundary, probably on the augite lamellae, which are structurally similar

J. SrepHEhr HUBBNBR

324

Naturally occurring sphalerite as a novel cost-effective photocatalyst for bacterial disinfection under visible light.  

PubMed

The photocatalytic disinfection capability of the natural semiconducting mineral sphalerite is studied here for the first time. Natural sphalerite can completely inactivate 1.5 × 10(7) cfu/mL E. coli K-12 within 6 h under visible light irradiation. The photocatalytic disinfection mechanism of natural sphalerite is investigated using multiple scavengers. The critical role that electrons play in bactericidal actions is experimentally demonstrated. The involvement of H(2)O(2) in photocatalytic disinfection is also confirmed using a partition system combined with different scavengers. Moreover, the photocatalytic destruction of bacterial cells is observed through transmission electron microscopic analysis. A catalase activity study reveals that antioxidative enzyme activity is high in the initial stage of photocatalytic disinfection but decreases with time due to damage to enzymatic functioning. Natural sphalerite is abundant and easy to obtain and possesses excellent visible-light photocatalytic activity. These superior properties make it a promising solar-driven photocatalyst for large-scale cost-effective wastewater treatment. PMID:21668021

Chen, Yanmin; Lu, Anhuai; Li, Yan; Zhang, Lisha; Yip, Ho Yin; Zhao, Huijun; An, Taicheng; Wong, Po-Keung

2011-06-14

325

A NATURALLY OCCURRING EPIGENETIC MUTATION IN AN SBP-BOX GENE INHIBITS TOMATO FRUIT RIPENING  

Technology Transfer Automated Retrieval System (TEKTRAN)

A major player in the regulatory network controlling fruit ripening is likely to be the gene at the tomato Colorless non-ripening (Cnr) locus 1,2. The Cnr mutation results in colorless fruits with a significant loss of cell to cell adhesion. The nature of the mutation and the identity of the Cnr g...

326

Food safety and risk assessment: naturally occurring potential toxicants and anti-nutritive compounds in plant foods.  

PubMed

The centralisation and globalisation of the world food supply presents opportunities for massive epidemics of food borne illness. Food processing generally decreases exposure to naturally occurring toxicants. A significant number of deaths are caused in both developed and developing countries from the consumption of naturally occurring toxicants and this exceeds the numbers attributable to artificial food contaminants and pollutants. The risk posed by naturally occurring toxicants is greater in developing countries where food choice and facilities for food processing are limited. The main risk in developed countries is from food important from areas where food safety controls are inadequate. Toxins derived from marine algae present a specific threat to health especially as seafood is being traded from areas where poisoning by algal toxins is known to occur. A systematic approach to food safety using HACCP methodology and identity preservation of the food are crucial in the prevention of food related illness. There is also a need for international agreed standards for tolerable levels of naturally occurring toxicants in foodstuffs but these should derived not be set unreasonably low as this would threaten food security in developing countries. The occurrence of a number of fatalities in developing countries among people consuming herbal teas and dietary supplements underscores the need to assess the safety of these products before they are placed on the market. PMID:15806954

Sanders, Thomas A B

2003-01-01

327

Detection of naturally occurring enteroviruses in waters using direct RT-PCR and integrated cell culture-RT-PCR  

Microsoft Academic Search

Viruses detected by rapid molecular assays are not always infectious. In this study we compared enterovirus levels in natural waters using culture and reverse transcription-polymerase chain reaction (RT-PCR) techniques to determine whether molecular units of naturally occurring enteroviruses can be utilized to predict viral infectivity. Viruses were concentrated from 12 river water and effluent samples using 1MDS filter–filtration and beef

Y. C. Shieh; C. I. Wong; J. A. Krantz; F. C. Hsu

2008-01-01

328

Naturally occurring wild relatives of temperate fruits in Western Himalayan region of India: an analysis  

Microsoft Academic Search

Wild relatives (WR) of temperate fruits belonging to genera viz., Malus, Prunus, Pyrus, Vitis, Rubus, Fragaria and others showed a wide range of diversity thereby possibility of utilizing large numbers of desirable genes\\/traits particularly\\u000a the resistance to biotic and abiotic stresses which is generally lacking in their cultivated allies. About 55 WR of 23 temperate\\u000a fruits, occurring in WH, including those

Jai Chand Rana; K. Pradheep; V. D. Verma

2007-01-01

329

Stratigraphic and geochemical controls on naturally occurring arsenic in groundwater, eastern Wisconsin, USA  

Microsoft Academic Search

High arsenic concentrations (up to 12,000mug\\/L) have been measured in groundwater from a confined sandstone aquifer in eastern Wisconsin. The main arsenic source is a sulfide-bearing secondary cement horizon (SCH) that has variable thickness, morphology, and arsenic concentrations. Arsenic occurs in pyrite and marcasite as well as in iron oxyhydroxides but not as a separate arsenopyrite phase. Nearly identical sulfur

M. E. Schreiber; J. A. Simo; P. G. Freiberg

2000-01-01

330

Stratigraphic and geochemical controls on naturally occurring arsenic in groundwater, eastern Wisconsin, USA  

Microsoft Academic Search

High arsenic concentrations (up to 12,000 7g\\/L) have been measured in groundwater from a confined sandstone aquifer in eastern Wisconsin. The main arsenic source is a sulfide-bearing secondary cement horizon (SCH) that has variable thickness, morphology, and arsenic concentrations. Arsenic occurs in pyrite and marcasite as well as in iron oxyhydroxides but not as a separate arsenopyrite phase. Nearly identical

M. E. Schreiber; J. A. Simo; P. G. Freiberg

2000-01-01

331

A naturally occurring nanomaterial from the Sundew (Drosera) for tissue engineering.  

PubMed

In recent years advances have been made in the design of novel materials for tissue engineering through the use of polysaccharides. This study evaluated the ability of a naturally secreted polysaccharide adhesive from the Sundew (Drosera capensis) as a support for cell growth. The Sundew adhesive has several advantages including its high elasticity and antibiotic nature. By coating glass cover slips with the Sundew adhesive, a network of nanofibers was generated that was capable of promoting attachment and differentiation of a model neuronal cell line, PC-12. We also demonstrated the potential of this material for repairing bone and soft tissue injuries, by testing attachment of osteoblasts and endothelial cells. Finally, it was determined that the Sundew biomaterial was stable through testing by atomic force microscopy and prolonged cell growth. This work has proven the capabilities of using a nanomaterial derived from the Sundew adhesive for the purpose of tissue engineering. PMID:22064887

Lenaghan, S C; Serpersu, K; Xia, L; He, W; Zhang, M

2011-11-07

332

Algal products as naturally occurring substrates for p-glycoprotein in Mytilus californianus  

Microsoft Academic Search

Mytilus californianus is a filter feeder that removes seaweed particulates, phytoplankton, and their byproducts from the water. The gills of this animal express high multixenobiotic resistance (MXR) and multixenobiotic transport activity that is related to the mammalian p-glycoprotein (p-gp). The high p-gp observed in mussel gills may provide the mussel protection from natural toxins in the diet. To test this

N. Eufemia; S. Clerte; S. Girshick; D. Epel

2002-01-01

333

Triple mechanisms of glyphosate-resistance in a naturally occurring glyphosate-resistant plant Dicliptera chinensis  

Microsoft Academic Search

Dicliptera chinensis Juss. is a unique annual plant that is naturally resistant to the herbicide glyphosate. We reported here the characterization of its 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), the target of glyphosate action. In comparison to the glyphosate-sensitive weed Ageratum houstonianum, D. chinensis had higher EPSPS activity, even before glyphosate treatment. Glyphosate treatment caused a significant increase in the EPSPS mRNA and

Chiou-Ing Yuan; Mou-Yen Chaing; Yih-Ming Chen

2002-01-01

334

Molecular structure of a naturally occurring alcohol dehydrogenase null activity allele in Drosophila melanogaster  

Microsoft Academic Search

An alcohol dehydrogenase null activity allele,AdhnAH52, extracted from a natural population ofDrosophila melanogaster has been cloned and sequenced. Compared with the wild-type consensus sequence, the nucleotide sequence ofAdhnAH52 contains eight extra bases in intron 2, adjacent to the 5' splice site. It seems likely that the extra bases result from two structural changes, with a 10-base pair insertion at the

John B. Gibson; Ann Verona Wilks

1989-01-01

335

Ursolic acid, a naturally occurring triterpenoid, demonstrates anticancer activity on human prostate cancer cells  

Microsoft Academic Search

Purpose  Glucocorticoids are widely used as adjuvant therapy in hormonal refractory prostate cancer; their therapeutic role, however,\\u000a remains unclear. Ursolic acid, a natural triterpene, structurally similar to dexamethasone, exhibits antitumor effects in\\u000a various cell types. Our main objective was to investigate the effects of ursolic acid on cell viability, apoptosis and bcl-2\\u000a protein, in human hormone refractory and androgen-sensitive prostate cancer

E. Kassi; Z. Papoutsi; H. Pratsinis; N. Aligiannis; M. Manoussakis; P. Moutsatsou

2007-01-01

336

Adjuvant activity of naturally occurring monophosphoryl lipopolysaccharide preparations from mucosa-associated bacteria.  

PubMed

Natural heterogeneity in the structure of the lipid A portion of lipopolysaccharide (LPS) produces differential effects on the innate immune response. Gram-negative bacterial species produce LPS structures that differ from the classic endotoxic LPS structures. These differences include hypoacylation and hypophosphorylation of the diglucosamine backbone, both differences known to decrease LPS toxicity. The effect of decreased toxicity on the adjuvant properties of many of these LPS structures has not been fully explored. Here we demonstrate that two naturally produced forms of monophosphorylated LPS, from the mucosa-associated bacteria Bacteroides thetaiotaomicron and Prevotella intermedia, function as immunological adjuvants for antigen-specific immune responses. Each form of mucosal LPS increased vaccination-initiated antigen-specific antibody titers in both quantity and quality when given simultaneously with vaccine antigen preparations. Interestingly, adjuvant effects on initial T cell clonal expansion were selective for CD4 T cells. No significant increase in CD8 T cell expansion was detected. MyD88/Toll-like receptor 4 (TLR4) and TRIF/TLR4 signaling pathways showed equally decreased signaling with the LPS forms studied here as with endotoxic LPS or detoxified monophosphorylated lipid A (MPLA). Natural monophosphorylated LPS from mucosa-associated bacteria functions as a weak but effective adjuvant for specific immune responses, with preferential effects on antibody and CD4 T cell responses over CD8 T cell responses. PMID:23798540

Chilton, Paula M; Hadel, Diana M; To, Thao T; Mitchell, Thomas C; Darveau, Richard P

2013-06-24

337

Stable water isotope characterization of human and natural impacts on land-atmosphere exchanges in the Amazon Basin  

Microsoft Academic Search

Stable water isotopes have been employed as a means of challenging, validating, and improving numerical models of the Amazon Basin since the 1980s. This paper serves as an exemplar of how characterization of human and natural impacts on surface-atmosphere water exchanges could beneficially exploit stable water isotope data and simulations. Interpretations of Amazonian isotopic data and model simulations are found

K. McGuffie; A. Henderson-Sellers

2004-01-01

338

ISOTOPE HYDROLOGY LABORATORY (WATER QUALITY MANAGEMENT BRANCH, WATER SUPPLY AND WATER RESOURCES DIVISION, NRMRL)  

EPA Science Inventory

The mission of NRMRL's Water Supply and Water Resources Division's Isotope Hydrology Laboratory (IHL) is to resolve environmental hydrology problems through research and application of naturally occurring isotopes. The emergent field of isotope hydrology follows advances in anal...

339

Preparation, characterization, and cation exchange selectivity of synthetic and topotactically altered naturally occurring trioctahedral micas  

NASA Astrophysics Data System (ADS)

The large quantity of high level nuclear waste held in underground stainless steel storage tanks around the country has necessitated the need for inorganic ion exchange materials with the ability to selectively remove radioactive species such as 137Cs and 90Sr in the presence of large concentrations of competing cations. Sodium expandable micas, such as sodium fluorophlogopite and K-depleted phlogopite have shown promise for this purpose. During this research highly charged sodium fluorophlogopite micas, Nax(Mg3)[AlxSi4-x]O 10F2·yH2O, with layer charges of -2, -3, and -4 per unit cell were synthesized from a dry mix of poorly crystalline kaolinite, Mg(NO3)2, and NaF. Additional silicon was also added to the reaction mixture in the form of amorphous SiO2 to increase the Si:Al ratio as needed. Talc was also utilized for the first time as Si and Mg sources in the synthesis of Na-2-mica. Potassium-depleted phlogopite, K1-xNax(Mg3)[AlSi3]O 10(OH)2, was prepared by conventional and microwave assisted equilibration of <45mum phlogopite mica with a solution containing sodium tetraphenylborate. The synthesized materials were characterized using X-ray diffraction, scanning electron microscopy, magic angle spinning nuclear magnetic resonance, and wet chemical techniques. Three synthetic sodium fluorophlogopite micas and one K-depleted phlogopite sample were selected for ion exchange studies. Ion exchange isotherms for the synthetic sodium fluorophlogopite micas were obtained for Cs+, Sr2+, Ba2+, and Co2+. For the K-depleted phlogopite ion exchange isotherms for Cs+ and Sr2+ were determined. The ion exchange studies indicated that only the Na-2-mica was selective for Cs+, all three micas were selective for Sr2+. All three mica also appeared to be highly selective for both Ba2+ and Co2+. The ion exchange studies indicated that the K-depleted phlogopite was highly selective for both Cs+ and Sr 2+. The ion selectivity of all of these micas indicates that they may be useful not only for removal of radioactive isotopes from the nuclear waste stream, but also removal of transition metal cations from industrial wastes.

Stout, Stephen Anthony

340

A coupled NMR and MS isotopic method for the authentication of natural vinegars  

Microsoft Academic Search

The natural site-specific deuterium content and the overall 13C content of acetic acids, extracted from vinegars or obtained by chemical synthesis, were determined by NMR and mass spectrometries. The isotope ratios (D\\/H)CH3 and the ?13C deviation of these samples were compared to those of a series of ethanols of the same natural or synthetic origins. The different groups of natural

Gérald Remaud; Claude Guillou; Claude Vallet; Gérard J. Martin

1992-01-01

341

Naturally occurring murine leukemia viruses in wild mice: characterization of a new "amphotropic" class.  

PubMed Central

A new class of murine leukemia viruses, isolated from wild Mus musculus trapped in California, is described. These viruses, designated "amphotropic," replicate in mouse, rabbit, mink, human, guinea pig, and rat cells, but not in hamster, quail, or duck cells. They show N-tropism for mouse cells, and do not trigger the XC cell response. They are distinct by interference and virus neutralization testing from the previously recognized mouse-tropic and xenotropic MuLV classes. Mouse-tropic viruses occuring along with three of the four amphotropic isolates were found to be distinguishable by virus neutralization from other mouse-tropic murine leukemia virus strains of laboratory mouse origin.

Hartley, J W; Rowe, W P

1976-01-01

342

When a natural disaster occurs: lessons learned in meeting students' needs.  

PubMed

Across the nation, weather-related natural disasters-tropical storms, floods, tornadoes, and earthquakes-struck even areas where weather concerns are not paramount on the minds of most people. These natural disasters heightened awareness that all geographic areas are susceptible to aberrant weather conditions. The purpose of this article was to relate the lessons learned by one academic health center in meeting students' emergency preparedness and disaster recovery needs following a major hurricane in fall 2008. To gauge students' storm-related needs, a Hurricane Needs Survey (HNS) was conducted in spring 2009, 7 months after the hurricane. Students responded to 26 structured response items and 3 open-ended questions. Five hundred fifteen surveys were completed, constituting a response rate of 37.2%. Data were analyzed by creating frequencies to profile students' hurricane experiences. Results indicated that all students left the island under mandatory evacuation orders; most stayed with their families, and most experienced moderate material losses. For some students, the evacuation process and life after the storm contributed to ongoing problems, worries, and academic performance issues. Qualitative content analysis was used to derive themes from the students' narrative responses to the HNS open-ended questions about their perceptions of the extent to which the University of Texas Medical Branch met their needs. When students' hurricane response comments were analyzed, three major themes emerged: being prepared, needing to be connected, and returning to normalcy. The major lessons learned are that the emergency preparation of students requires greater specificity and that discussion about poststorm recovery expectations is essential. Following a natural disaster, students experience more distress than may be readily apparent. PMID:22142912

Watson, Pamela G; Loffredo, Vincent J; McKee, John C

343

Bioaccumulation of Naturally Occurring Mixed Halogenated Dimethylbipyrroles in Whale and Dolphin Products on the Japanese Market  

Microsoft Academic Search

Mixed halogenated dimethyl bipyrroles (HDBPs), which are thought to be produced naturally, were quantified in whale and dolphin\\u000a products marketed for human consumption in Japan. The major component of HDBPs was 3,3?,4,4?-tetrabromo-5,5?-dichloro-1,1?-dimethyl\\u000a -2,2?-bipyrrole (Br4Cl2-DBP), accounting for 85% of the total of five HDBPs detected, followed by Br3Cl2-DBP. Mean concentrations of HDBPs ranged from 0.27 ?g\\/g lipid (n = 31) in minke

K. Haraguchi; Y. Hisamichi; T. Endo

2006-01-01

344

Characterization and molecular mechanism of a naturally occurring metsulfuron-methyl resistant strain of Pseudomonas aeruginosa  

Microsoft Academic Search

Strain L36, naturally resistant to the herbicide metsulfuron-methyl (SM), was isolated and characterized with respect to the\\u000a molecular mechanism of resistance. The isolate was identified as Pseudomonas aeruginosa based on bacterial morphology, physiology, cellular fatty acid, and 16S rRNA gene sequence. Minimal inhibitory concentrations\\u000a of metsulfuron-methyl against the growth of L36 and wild type isolate PAO1 were 6.03 and 1.33 mM,

Xing HuangJian; Jian He; Xiao-Fei Sun; Ji-Quan Sun; Yong-Feng Li; Jing-Jing Shen; Shun-Peng Li

2010-01-01

345

Molecular structure of a naturally occurring alcohol dehydrogenase null activity allele in Drosophila melanogaster  

Microsoft Academic Search

An alcohol dehydrogenase null activity allele,Adh\\u000a \\u000a nAH52\\u000a , extracted from a natural population ofDrosophila melanogaster has been cloned and sequenced. Compared with the wild-type consensus sequence, the nucleotide sequence ofAdh\\u000a \\u000a nAH52\\u000a contains eight extra bases in intron 2, adjacent to the 5' splice site. It seems likely that the extra bases result from\\u000a two structural changes, with a 10-base pair

John B. Gibson; Ann Verona Wilks

1989-01-01

346

Genetic variation for an aphid wing polyphenism is genetically linked to a naturally occurring wing polymorphism.  

PubMed

Many polyphenisms are examples of adaptive phenotypic plasticity where a single genotype produces distinct phenotypes in response to environmental cues. Such alternative phenotypes occur as winged and wingless parthenogenetic females in the pea aphid (Acyrthosiphon pisum). However, the proportion of winged females produced in response to a given environmental cue varies between clonal genotypes. Winged and wingless phenotypes also occur in males of the sexual generation. In contrast to parthenogenetic females, wing production in males is environmentally insensitive and controlled by the sex-linked, biallelic locus, aphicarus (api). Hence, environmental or genetic cues induce development of winged and wingless phenotypes at different stages of the pea aphid life cycle. We have tested whether allelic variation at the api locus explains genetic variation in the propensity to produce winged females. We assayed clones from an F2 cross that were heterozygous or homozygous for alternative api alleles for their propensity to produce winged offspring. We found that clones with different api genotypes differed in their propensity to produce winged offspring. The results indicate genetic linkage of factors controlling the female wing polyphenism and male wing polymorphism. This finding is consistent with the hypothesis that genotype by environment interaction at the api locus explains genetic variation in the environmentally cued wing polyphenism. PMID:15817441

Braendle, Christian; Friebe, Ilvy; Caillaud, Marina C; Stern, David L

2005-03-22

347

Phenylpropanoids as naturally occurring antioxidants: from plant defense to human health.  

PubMed

Phenylpropanoids (PPs) belong to the largest group of secondary metabolites produced by plants, mainly, in response to biotic or abiotic stresses such as infections, wounding, UV irradiation, exposure to ozone, pollutants, and other hostile environmental conditions. It is thought that the molecular basis for the protective action of phenylpropanoids in plants is their antioxidant and free radical scavenging properties. These numerous phenolic compounds are major biologically active components of human diet, spices, aromas, wines, beer, essential oils, propolis, and traditional medicine. Last few years, much interest has been attracted to natural and synthetic phenylpropanoids for medicinal use as antioxidant, UV screens, anticancer, anti-virus, anti-inflammatory, wound healing, and antibacterial agents. They are of great interest for cosmetic and perfume industries as active natural ingredients. In the present review, the metabolic pathways of phenylpropanoid biosynthesis in plants and the mechanism of phenylpropanoid-mediated plant defense are described. Learning from plants, free radical-driven, molecular and cellular processes modulated by phenylpropanoids in human cell cultures in vitro and in the in vivo animal models of tumors, inflammation, and cellular damage are also reviewed. PMID:17519109

Korkina, L G

2007-04-15

348

Rapid formation of N-nitrosodimethylamine from gramine, a naturally occurring precursor in barley malt.  

PubMed

The two tertiary amine alkaloids, hordenine and gramine, which are biosynthesized in malt during germination, were subjected to nitrosation under conditions typical for the study of tertiary amine nitrosation. At 65 degrees C in dilute aqueous acid (pH 4.4 or pH 6.4), nitrosation of both amines resulted in formation of N-nitrosodimethylamine (NDMA). At 24 degrees C in dilute acid (pH 3.4), the initial rate of NDMA formation from gramine was nearly equal to the initial rate of NDMA formation from dimethylamine. At the same temperature, the ratio of initial rates of formation of NDMA from gramine and trimethylamine was 6250:1. At 23 degrees C, the ratio of initial rates of formation of NDMA from gramine and hordenine was 5200:1. The rapid reaction of gramine with nitrous acid and the nature of the gramine nitrosation reaction products both indicated that gramine did not undergo nitrosation by the expected mechanism of nitrosative dealkylation. A new mechanism if proposed to explain the labile nature of the dimethylamino group of gramine and to account for the fact that NDMA is the only N-nitrosamine formed during the nitrosation of gramine. PMID:6533024

Mangino, M M; Scanlan, R A

1984-01-01

349

Recruiting Older Adults into a Physical Activity Promotion Program: "Active Living Every Day" Offered in a Naturally Occurring Retirement Community  

ERIC Educational Resources Information Center

|Purpose: This article explores recruitment strategies based on the transtheoretical model (TTM) with older adults living in a naturally occurring retirement community (NORC) to encourage enrollment in a physical activity promotion program, "Active Living Every Day" (ALED). Reasons for participation or nonparticipation are identified. Design and…

Hildebrand, Mary; Neufeld, Peggy

2009-01-01

350

Recruiting Older Adults into a Physical Activity Promotion Program: "Active Living Every Day" Offered in a Naturally Occurring Retirement Community  

ERIC Educational Resources Information Center

Purpose: This article explores recruitment strategies based on the transtheoretical model (TTM) with older adults living in a naturally occurring retirement community (NORC) to encourage enrollment in a physical activity promotion program, "Active Living Every Day" (ALED). Reasons for participation or nonparticipation are identified. Design and…

Hildebrand, Mary; Neufeld, Peggy

2009-01-01

351

Troglitazone prevents and reverses dyslipidemia, insulin secretory defects, and histologic abnormalities in a rat model of naturally occurring obese diabetes  

Microsoft Academic Search

Troglitazone has been shown to improve insulin sensitivity and thereby exert hypoglycemic effects in various animal models and humans with insulin resistance and diabetes. The recently established animal model of naturally occurring obese diabetes, the Otsuka Long-Evans Tokushima fatty (OLETF) rat, has many similarities with human type 2 diabetes mellitus and is characterized by a high degree of insulin resistance.

Dong Mei Jia; Akinari Tabaru; Hayato Nakamura; Ken-Ichiro Fukumitsu; Toshiharu Akiyama; Makoto Otsuki

2000-01-01

352

Elevated Appraisals of the Negative Impact of Naturally Occurring Life Events: A Risk Factor for Depressive and Anxiety Disorders  

ERIC Educational Resources Information Center

|The tendency to appraise naturally occurring life events (LEs) as having high negative impact may be a predisposing factor for the development of depression and anxiety disorders. In the current study, appraisals of the negative impact of recent LEs were examined in relationship to depressive and anxiety disorders in a sample of 653 adolescents…

Espejo, Emmanuel Peter; Hammen, Constance; Brennan, Patricia A.

2012-01-01

353

Fuzzy rule-based modelling for human health risk from naturally occurring radioactive materials in produced water  

Microsoft Academic Search

Produced water, discharged from offshore oil and gas operations, contains chemicals from formation water, condensed water, and any chemical added down hole or during the oil\\/water separation process. Although, most of the contaminants fall below the detection limits within a short distance from the discharge port, a few of the remaining contaminants including naturally occurring radioactive materials (NORM) are of

Chowdhury Shakhawat; Husain Tahir; Bose Neil

2006-01-01

354

The Case of an In-Home Recreation Program for an Older Adult in a Naturally Occurring Retirement Community (NORC).  

ERIC Educational Resources Information Center

|Describes the implementation of an in-home therapeutic recreation (TR) program with an elderly woman living in a naturally occurring retirement community (NORC) by a fourth-year TR student. The program helped meet her physical, social, and cognitive needs and re-stimulate her interests. Results suggest that in-home TR can be beneficial, and TR…

Chow, Yvette

2002-01-01

355

A novel Arometic compound acts synergistically with a naturally occurring monoterpene to elicit strong behavioral responses in Asian citrus psyllid  

Technology Transfer Automated Retrieval System (TEKTRAN)

Inscent, Inc. has developed methodologies for rapidly screening potential ligands of chemosensory proteins (CSPs) isolated from the antennae of target insects. These novel ligands, referred to as Arometics, mimic naturally-occurring odorants and may function as super-stimuli because of their strong ...

356

Naturally occurring radioactive material from the aluminium industry—a case study: the Egyptian Aluminium Company, Nag Hammady, Egypt  

Microsoft Academic Search

The activity concentrations and the gamma-absorbed dose rates of the terrestrial naturally occurring radionuclides 226Ra and 232Th were determined in samples of bauxite, alumina and aluminium dross tailings industrial waste (used to produce two types of alums) using high purity germanium (HPGe) gamma ray spectrometry. The bauxite and alumina are imported by Egyptalum (The Egyptian Aluminium Company, Nag Hammady, Egypt)

Adel G E Abbady; A M El-Arabi

2006-01-01

357

Naturally occurring radioactive material from the aluminium industry---a case study: the Egyptian Aluminium Company, Nag Hammady, Egypt  

Microsoft Academic Search

The activity concentrations and the gamma-absorbed dose rates of the terrestrial naturally occurring radionuclides 226Ra and 232Th were determined in samples of bauxite, alumina and aluminium dross tailings industrial waste (used to produce two types of alums) using high purity germanium (HPGe) gamma ray spectrometry. The bauxite and alumina are imported by Egyptalum (The Egyptian Aluminium Company, Nag Hammady, Egypt)

Adel G. E. Abbady; A. M. El-Arabi

2006-01-01

358

Upper limits for the existence of long-lived isotopes of roentgenium in natural gold  

SciTech Connect

A sensitive search for isotopes of a superheavy element (SHE) in natural gold materials has been performed with accelerator mass spectrometry at the Vienna Environmental Research Accelerator, which is based on a 3-MV tandem accelerator. Because the most likely SHE in gold is roentgenium (Rg, Z = 111), the search concentrated on Rg isotopes. Two different mass regions were explored: (i) For the neutron-deficient isotopes {sup 261}Rg and {sup 265}Rg, abundance limits in gold of 3x10{sup -16} were reached (no events observed). This is in stark contrast to the findings of Marinov et al.[Int. J. Mod. Phys. E 18, 621 (2009)], who reported positive identification of these isotopes with inductively coupled plasma sector field mass spectrometry in the (1-10)x10{sup -10} abundance range. (ii) Theoretical models of SHEs predict a region of increased stability around the proton and neutron shell closures of Z = 114 and N = 184. We therefore investigated eight heavy Rg isotopes, {sup A}Rg, A = 289, 290, 291, 292, 293, 294, 295, and 296. For six isotopes no events were observed, setting limits also in the 10{sup -16} abundance range. For {sup 291}Rg and {sup 294}Rg we observed two and nine events, respectively, which results in an abundance in the 10{sup -15} range. However, pileup of a particularly strong background in these cases makes a positive identification as Rg isotopes--even after pileup correction--unlikely.

Dellinger, F.; Kutschera, W.; Forstner, O.; Golser, R.; Priller, A.; Steier, P.; Wallner, A.; Winkler, G. [University of Vienna, Faculty of Physics, Vienna Environmental Research Accelerator (VERA) Laboratory, Waehringer Strasse 17, A-1090 Wien (Austria)

2011-01-15

359

Rapidly assessing changes in bone mineral balance using natural stable calcium isotopes  

PubMed Central

The ability to rapidly detect changes in bone mineral balance (BMB) would be of great value in the early diagnosis and evaluation of therapies for metabolic bone diseases such as osteoporosis and some cancers. However, measurements of BMB are hampered by difficulties with using biochemical markers to quantify the relative rates of bone resorption and formation and the need to wait months to years for altered BMB to produce changes in bone mineral density large enough to resolve by X-ray densitometry. We show here that, in humans, the natural abundances of Ca isotopes in urine change rapidly in response to changes in BMB. In a bed rest experiment, use of high-precision isotope ratio MS allowed the onset of bone loss to be detected in Ca isotope data after about 1 wk, long before bone mineral density has changed enough to be detectable with densitometry. The physiological basis of the relationship between Ca isotopes and BMB is sufficiently understood to allow quantitative translation of changes in Ca isotope abundances to changes in bone mineral density using a simple model. The rate of change of bone mineral density inferred from Ca isotopes is consistent with the rate observed by densitometry in long-term bed rest studies. Ca isotopic analysis provides a powerful way to monitor bone loss, potentially making it possible to diagnose metabolic bone disease and track the impact of treatments more effectively than is currently possible.

Morgan, Jennifer L. L.; Skulan, Joseph L.; Gordon, Gwyneth W.; Romaniello, Stephen J.; Smith, Scott M.; Anbar, Ariel D.

2012-01-01

360

Rapidly assessing changes in bone mineral balance using natural stable calcium isotopes.  

PubMed

The ability to rapidly detect changes in bone mineral balance (BMB) would be of great value in the early diagnosis and evaluation of therapies for metabolic bone diseases such as osteoporosis and some cancers. However, measurements of BMB are hampered by difficulties with using biochemical markers to quantify the relative rates of bone resorption and formation and the need to wait months to years for altered BMB to produce changes in bone mineral density large enough to resolve by X-ray densitometry. We show here that, in humans, the natural abundances of Ca isotopes in urine change rapidly in response to changes in BMB. In a bed rest experiment, use of high-precision isotope ratio MS allowed the onset of bone loss to be detected in Ca isotope data after about 1 wk, long before bone mineral density has changed enough to be detectable with densitometry. The physiological basis of the relationship between Ca isotopes and BMB is sufficiently understood to allow quantitative translation of changes in Ca isotope abundances to changes in bone mineral density using a simple model. The rate of change of bone mineral density inferred from Ca isotopes is consistent with the rate observed by densitometry in long-term bed rest studies. Ca isotopic analysis provides a powerful way to monitor bone loss, potentially making it possible to diagnose metabolic bone disease and track the impact of treatments more effectively than is currently possible. PMID:22652567

Morgan, Jennifer L L; Skulan, Joseph L; Gordon, Gwyneth W; Romaniello, Stephen J; Smith, Scott M; Anbar, Ariel D

2012-05-31

361

Upper limits for the existence of long-lived isotopes of roentgenium in natural gold  

NASA Astrophysics Data System (ADS)

A sensitive search for isotopes of a superheavy element (SHE) in natural gold materials has been performed with accelerator mass spectrometry at the Vienna Environmental Research Accelerator, which is based on a 3-MV tandem accelerator. Because the most likely SHE in gold is roentgenium (Rg, Z = 111), the search concentrated on Rg isotopes. Two different mass regions were explored: (i) For the neutron-deficient isotopes Rg261 and Rg265, abundance limits in gold of 3×10-16 were reached (no events observed). This is in stark contrast to the findings of Marinov [Int. J. Mod. Phys. EIMPEER0218-301310.1142/S021830130901280X 18, 621 (2009)], who reported positive identification of these isotopes with inductively coupled plasma sector field mass spectrometry in the (1-10)×10-10 abundance range. (ii) Theoretical models of SHEs predict a region of increased stability around the proton and neutron shell closures of Z = 114 and N = 184. We therefore investigated eight heavy Rg isotopes, ARg, A = 289, 290, 291, 292, 293, 294, 295, and 296. For six isotopes no events were observed, setting limits also in the 10-16 abundance range. For Rg291 and Rg294 we observed two and nine events, respectively, which results in an abundance in the 10-15 range. However, pileup of a particularly strong background in these cases makes a positive identification as Rg isotopes—even after pileup correction—unlikely.

Dellinger, F.; Kutschera, W.; Forstner, O.; Golser, R.; Priller, A.; Steier, P.; Wallner, A.; Winkler, G.

2011-01-01

362

Interactions between natural-occurring landscape conditions and land use influencing the abundance of riverine smallmouth bass, micropterus dolomieu  

USGS Publications Warehouse

This study examined how interactions between natural landscape features and land use influenced the abundance of smallmouth bass, Micropterus dolomieu, in Missouri, USA, streams. Stream segments were placed into one of four groups based on natural-occurring watershed characteristics (soil texture and soil permeability) predicted to relate to smallmouth bass abundance. Within each group, stream segments were assigned forest (n = 3), pasture (n = 3), or urban (n = 3) designations based on the percentages of land use within each watershed. Analyses of variance indicated smallmouth bass densities differed between land use and natural conditions. Decision tree models indicated abundance was highest in forested stream segments and lowest in urban stream segments, regardless of group designation. Land use explained the most variation in decision tree models, but in-channel features of temperature, flow, and sediment also contributed significantly. These results are unique and indicate the importance of natural-occurring watershed conditions in defining the potential of populations and how finer-scale filters interact with land use to further alter population potential. Smallmouth bass has differing vulnerabilities to land-use attributes, and the better the natural watershed conditions are for population success, the more resilient these populations will be when land conversion occurs.

Brewer, S. K.; Rabeni, C. F.

2011-01-01

363

The atomic weight and isotopic composition of nitrogen and their variation in nature  

SciTech Connect

Two stable isotopes of nitrogen exist in nature, /sup 14/N and /sup 15/N. The less abundant isotope, /sup 15/N, was discovered in 1929 by Naude, who studied the band spectra of nitric oxide, NO. However, the main source of a standard for this element is the air in the atmosphere, which is made up of approximately 78% N/sub 2/. Reviewed in this paper is the measurements of the isotopic composition in air and its variation around the world. Also investigated is the variation of the isotopic composition in the various compounds or sources of nitrogen compared to the value in air. Data on the atomic weight and non-terrestrial data for nitrogen is also reviewed.

Holden, N.E.

1987-01-01

364

Automated determination of silicon isotope natural abundance by the acid decomposition of cesium hexafluosilicate.  

PubMed

A procedure for the automated determination of isotopic abundances of silicon from biogenic and lithogenic particulate matter and from dissolved silicon in fresh or saltwaters is reported. Samples are purified using proven procedures through the reaction of Si with acidified ammonium molybdate, followed by precipitation with triethylamine and combustion of the precipitate to yield silicon dioxide. The silicon dioxide is converted to cesium hexafluosilicate by dissolution in hydrogen fluoride and the addition of cesium chloride. Isotopic analysis is accomplished by decomposing the cesium hexafluosilicate with concentrated sulfuric acid to generate silicon tetrafluoride gas. Silicon tetrafluoride is purified cryogenically and analyzed on a gas source isotope ratio mass spectrometer. Yields of silicon tetrafluoride are >99.5%. The procedure can be automated by modifying commercial inlet systems designed for carbonate analysis. The procedure is free of memory effects and isotopic biases. Reproducibility is +/-0.03-0.10 per thousand for a variety of natural and synthetic materials. PMID:16944891

Brzezinski, Mark A; Jones, Janice L; Beucher, Charlotte P; Demarest, Mark S; Berg, Howard L

2006-09-01

365

Realtime stable isotope monitoring of natural waters by parallel-flow laser spectroscopy.  

PubMed

A parallel-flow H(2)O(liquid)-H(2)O(vapor) equilibration and laser spectroscopy method provides a new way to monitor the hydrogen and oxygen stable isotopic composition of water from rivers or lakes or in hydrologic tracer tests in real time. Two custom-built equilibrator devices and one commercial membrane device were tested to determine if they could be used to convert natural water samples (lakes, rivers, groundwater) to a H(2)O gas phase for continuous online ?(18)O and ?D isotopic analysis by laser spectroscopy. Both the commercial minimodule device and the marble-filled equilibrator produced water vapor in isotopic equilibrium with the flowing liquid water, suggesting that unattended field measurement using these devices is possible. Oxygen isotope disequilibrium was indicated using the minimodule device at low temperatures. PMID:21214188

Koehler, Geoff; Wassenaar, Leonard I

2011-01-07

366

Ba isotopic signature for early differentiation between Cs and Ba in natural fission reactors  

NASA Astrophysics Data System (ADS)

Ba isotopic studies of the Oklo and Bangombé natural fission reactors in east Gabon provide information on the geochemical behavior of radioactive Cs ( 135Cs and 137Cs) in a geological medium. Large isotopic deviations derived from fissiogenic Ba were found in chemical leachates of the reactor uraninites. The fissiogenic Ba isotopic patterns calculated by subtracting the non-fissiogenic component are classified into three types that show different magnifications of chemical fractionation between Cs and Ba. In addition, the isotopic signatures of fissiogenic 135Ba, 137Ba and 138Ba suggest an early differentiation between Cs and Ba of less than 20 years after the production of fissiogenic Cs and Ba. On the other hand, only small excesses of 135Ba ( ? < +1.8) and/or 137Ba ( ? < +1.3) were identified in some clay samples, which might have resulted from selective adsorption of 135Cs and 137Cs that migrated from the reactors by differentiation.

Hidaka, Hiroshi; Gauthier-Lafaye, François

2008-08-01

367

Naturally occurring tyrosinase inhibitors: mechanism and applications in skin health, cosmetics and agriculture industries.  

PubMed

Tyrosinase is a copper-containing enzyme, which is widely distributed in microorganisms, animals and plants and is a key enzyme in melanin biosynthesis, involved in determining the color of mammalian skin and hair. In addition, unfavorable enzymatic browning of plant-derived foods by tyrosinase causes a decrease in nutritional quality and economic loss of food products. The inadequacy of current conventional methods to prevent tyrosinase action encourages researchers to seek new potent tyrosinase inhibitors for food and cosmetics. This article presents a study on the importance of tyrosinase, biochemical characteristics, type of inhibitions, activators from various natural sources with its clinical and industrial importance in recent prospects is discussed in this paper. PMID:17605157

Parvez, Shoukat; Kang, Moonkyu; Chung, Hwan-Suck; Bae, Hyunsu

2007-09-01

368

Schwann cell hyperplasia and tumors in transgenic mice expressing a naturally occurring mutant NF2 protein.  

PubMed

Specific mutations in some tumor suppressor genes such as p53 can act in a dominant fashion. We tested whether this mechanism may also apply for the neurofibromatosis type-2 gene (NF2) which, when mutated, leads to schwannoma development. Transgenic mice were generated that express, in Schwann cells, mutant NF2 proteins prototypic of natural mutants observed in humans. Mice expressing a NF2 protein with an interstitial deletion in the amino-terminal domain showed high prevalence of Schwann cell-derived tumors and Schwann cell hyperplasia, whereas those expressing a carboxy-terminally truncated protein were normal. Our results indicate that a subset of mutant NF2 alleles observed in patients may encode products with dominant properties when overexpressed in specific cell lineages. PMID:10215625

Giovannini, M; Robanus-Maandag, E; Niwa-Kawakita, M; van der Valk, M; Woodruff, J M; Goutebroze, L; Mérel, P; Berns, A; Thomas, G

1999-04-15

369

Schwann cell hyperplasia and tumors in transgenic mice expressing a naturally occurring mutant NF2 protein  

PubMed Central

Specific mutations in some tumor suppressor genes such as p53 can act in a dominant fashion. We tested whether this mechanism may also apply for the neurofibromatosis type-2 gene (NF2) which, when mutated, leads to schwannoma development. Transgenic mice were generated that express, in Schwann cells, mutant NF2 proteins prototypic of natural mutants observed in humans. Mice expressing a NF2 protein with an interstitial deletion in the amino-terminal domain showed high prevalence of Schwann cell-derived tumors and Schwann cell hyperplasia, whereas those expressing a carboxy-terminally truncated protein were normal. Our results indicate that a subset of mutant NF2 alleles observed in patients may encode products with dominant properties when overexpressed in specific cell lineages.

Giovannini, Marco; Robanus-Maandag, Els; Niwa-Kawakita, Michiko; van der Valk, Martin; Woodruff, James M.; Goutebroze, Laurence; Merel, Philippe; Berns, Anton; Thomas, Gilles

1999-01-01

370

Nature and nurture: Environmental isotope story of the River Rhine  

Microsoft Academic Search

The total dissolved load of the Rhine river increases downstream due to the combined impact of natural and pollution loads. The natural background, controlled by geology, is soon swamped by pollution, particularly from salt and coal mining activities in Alsace and the Ruhr area. The Rhine is also a net source of CO2 from oxidation of excess organic productivity that

D. Buhl; R. D. Neuser; D. K. Richter; D. Riedel; B. Roberts; H. Strauss; J. Veizer

1991-01-01

371

An Isotope Fractionation - Reactive Transport Model to Assess Natural Attenuation of Chlorinated Solvents  

NASA Astrophysics Data System (ADS)

While compound-specific isotope analysis has been used successfully to demonstrate in situ degradation of chlorinated solvents, it suffers from uncertainty resulting from geological heterogeneity and variability in redox conditions. The primary objective of this project was to create an Isotope Fractionation - Reactive Transport Model (IF-RTM) capable of simultaneously simulating multiple isotopes within a complex reaction network, in this case C, Cl and H isotopes during the sequential degradation of chlorinated ethenes, and with heterogeneous environmental conditions. This IF-RTM can then be used as a tool to quantitatively assess contaminant mass destruction through natural attenuation processes, potentially reducing the required monitoring effort, informing remediation or mitigation efforts, and providing insight into the relative impacts of mass attenuation mechanisms. A greater level of model confidence can be obtained by incorporating isotope fractionation into the model output, rather than the usual concentration only approach. A model code capable of simulating concentration changes and isotope fractionation of multiple isotopes (C, Cl, H) during reductive dechlorination and aerobic degradation has been developed using the biogeochemical speciation and transport modelling programme PHREEQC-2. This model is novel not only because it simulates multiple isotopes, but also because it also incorporates secondary isotope effects in the simulation of chlorine isotope fractionation. Microcosm data, including a dataset representing the first a comprehensive, three-isotope (C, Cl, H) characterisation of the TCE reductive dechlorination sequence will be presented and have been used to calibrate/validate this model. The model was found to be capable of simulating the carbon, chlorine and hydrogen isotope fractionation patterns and change in concentration for TCE and its degradation products throughout the reductive dechlorination process. In the next stage of this project solute transport capability will be added to the model by modifying it to be used with a reactive multi-component transport model such as PHAST. The final IF-RTM product will have the capability of simulating changes in concentrations of the parent compound (e.g. PCE) and its degradation products (e.g. VC) and the isotope ratios (of C, Cl and H) of each compound in 3D space. This IF-RTM can also be modified to include fractionation resulting from physical processes such as hydrodynamic dispersion. The developed model will be tested on a large dataset collected at a contaminated field site, namely the TCE plume at Hill AFB, UT.

Stack, P.; Kuder, T.; Vanderford, M.; Philp, P.; van Breukelen, B.

2012-04-01

372

Hidden localization motifs: naturally occurring peroxisomal targeting signals in non-peroxisomal proteins  

PubMed Central

Background Can sequence segments coding for subcellular targeting or for posttranslational modifications occur in proteins that are not substrates in either of these processes? Although considerable effort has been invested in achieving low false-positive prediction rates, even accurate sequence-analysis tools for the recognition of these motifs generate a small but noticeable number of protein hits that lack the appropriate biological context but cannot be rationalized as false positives. Results We show that the carboxyl termini of a set of definitely non-peroxisomal proteins with predicted peroxisomal targeting signals interact with the peroxisomal matrix protein receptor peroxin 5 (PEX5) in a yeast two-hybrid test. Moreover, we show that examples of these proteins - chicken lysozyme, human tyrosinase and the yeast mitochondrial ribosomal protein L2 (encoded by MRP7) - are imported into peroxisomes in vivo if their original sorting signals are disguised. We also show that even prokaryotic proteins can contain peroxisomal targeting sequences. Conclusions Thus, functional localization signals can evolve in unrelated protein sequences as a result of neutral mutations, and subcellular targeting is hierarchically organized, with signal accessibility playing a decisive role. The occurrence of silent functional motifs in unrelated proteins is important for the development of sequence-based function prediction tools and the interpretation of their results. Silent functional signals have the potential to acquire importance in future evolutionary scenarios and in pathological conditions.

Neuberger, Georg; Kunze, Markus; Eisenhaber, Frank; Berger, Johannes; Hartig, Andreas; Brocard, Cecile

2004-01-01

373

A naturally occurring allele of BRCA1 coding for a temperature-sensitive mutant protein.  

PubMed

Recent evidence suggests that the breast and ovarian cancer susceptibility gene product BRCA1 is involved in at least two fundamental cellular processes: transcriptional regulation and DNA repair. However, the mechanism of action of BRCA1 in either of these processes is still unknown. Here, we report the characterization of a disease-predisposing allele of BRCA1, identified in a family with several cases of ovarian cancer, coding for a protein that displays temperature-sensitive activity in transcriptional activation. The mutant protein differs from the wild type protein at a single amino acid, R1699W that occurs in a region at the N-terminal BRCT domain that is highly conserved among BRCA1 homologs. When the C-terminus of the mutant protein (aa 1560-1863) was fused to a heterologous GAL4 DNA-binding domain and expressed in yeast or mammalian cells, it was able to activate transcription of a reporter gene to levels observed for wild type BRCA1 at the permissive temperature (30 degrees C) but exhibited significantly less transcription activity at the restrictive temperature (37 degrees C or 39 degrees C). Our results indicate that the transcriptional activity of the R1699W mutant can be modulated as a function of temperature and provide a novel experimental approach which can be utilized to dissect the molecular mechanism(s) of BRCA1 in processes related to transcription. PMID:12496476

Worley, Terri; Vallon-Christersson, Johan; Billack, Blase; Borg, Ake; Monteiro, Alvaro N A

374

Hepatitis B virus capsid assembly is enhanced by naturally occurring mutation F97L.  

PubMed

In chronic hepatitis B virus (HBV) infections, one of the most common mutations to the virus occurs at amino acid 97 of the core protein, where leucine replaces either phenylalanine or isoleucine, depending on strain. This mutation correlates with changes in viral nucleic acid metabolism and/or secretion. We hypothesize that this phenotype is due in part to altered core assembly, a process required for DNA synthesis. We examined in vitro assembly of empty HBV capsids from wild-type and F97L core protein assembly domains. The mutation enhanced both the rate and extent of assembly relative to those for the wild-type protein. The difference between the two proteins was most obvious in the temperature dependence of assembly, which was dramatically stronger for the mutant protein, indicating a much more positive enthalpy. Since the structures of the mutant and wild-type capsids are essentially the same and the mutation is not involved in the contact between dimers, we suggest that the F97L mutation affects the dynamic behavior of dimer and capsid. PMID:15308745

Ceres, Pablo; Stray, Stephen J; Zlotnick, Adam

2004-09-01

375

Phylogeny and Virulence of Naturally Occurring Type III Secretion System-Deficient Pectobacterium Strains?  

PubMed Central

Pectobacterium species are enterobacterial plant-pathogenic bacteria that cause soft rot disease in diverse plant species. Previous epidemiological studies of Pectobacterium species have suffered from an inability to identify most isolates to the species or subspecies level. We used three previously described DNA-based methods, 16S-23S intergenic transcribed spacer PCR-restriction fragment length polymorphism analysis, multilocus sequence analysis (MLSA), and pulsed-field gel electrophoresis, to examine isolates from diseased stems and tubers and found that MLSA provided the most reliable classification of isolates. We found that strains belonging to at least two Pectobacterium clades were present in each field examined, although representatives of only three of five Pectobacterium clades were isolated. Hypersensitive response and DNA hybridization assays revealed that strains of both Pectobacterium carotovorum and Pectobacterium wasabiae lack a type III secretion system (T3SS). Two of the T3SS-deficient strains assayed lack genes adjacent to the T3SS gene cluster, suggesting that multiple deletions occurred in Pectobacterium strains in this locus, and all strains appear to have only six rRNA operons instead of the seven operons typically found in Pectobacterium strains. The virulence of most of the T3SS-deficient strains was similar to that of T3SS-encoding strains in stems and tubers.

Kim, Hye-Sook; Ma, Bing; Perna, Nicole T.; Charkowski, Amy O.

2009-01-01

376

A Naturally Occurring Outbreak of Tuberculosis in a Group of Imported Cynomolgus Monkeys (Macaca fascicularis)  

PubMed Central

This case report describes the diagnosis of tuberculosis (caused primarily by Mycobacterium bovis) in a group of newly imported Chinese origin cynomolgus monkeys. We also describe the use of sedation to enhance the accuracy of evaluation of the intrapalpebral tuberculin skin test using the mammalian old tuberculin reagent and report the first known diagnosis of Mycobacterium paraffinicum in a nonhuman primate. By 48 h after injection during the second tuberculin skin test, 6 of the 80 macaques had developed eyelid reactions ranging from mild (grade 1) to severe (grade 4). Given the range and severity of reactions, we suspected an outbreak of tuberculosis in the group. Because of the nature of the reactions, we sedated the animals at the 72-h evaluation to more closely observe and then palpate the injected eyelid. Evaluation of unsedated animals revealed 22 with a reaction to mammalian old tuberculin. We confirmed these 22 cases and identified an additional 11 animals with reactions when the monkeys were sedated. Mycobacterial culture of tissue from 6 macaques with reactions confirmed M. bovis in 3 animals. In addition, 1 of these 3 animals was culture-positive for both M. bovis and M. paraffinicum, and another was culture-positive for M. avium complex only. The addition of sedation to facilitate visual inspection and then palpation of the injected eyelid of these macaques increased the accuracy of evaluation and understanding of the number and severity of reactions to tuberculin skin testing.

Panarella, Matthew L; Bimes, Randy S

2010-01-01

377

Correlation of Naturally Occurring HIV-1 Resistance to DEB025 with Capsid Amino Acid Polymorphisms  

PubMed Central

DEB025 (alisporivir) is a synthetic cyclosporine with inhibitory activity against human immunodeficiency virus type-1 (HIV-1) and hepatitis C virus (HCV). It binds to cyclophilin A (CypA) and blocks essential functions of CypA in the viral replication cycles of both viruses. DEB025 inhibits clinical HIV-1 isolates in vitro and decreases HIV-1 virus load in the majority of patients. HIV-1 isolates being naturally resistant to DEB025 have been detected in vitro and in nonresponder patients. By sequence analysis of their capsid protein (CA) region, two amino acid polymorphisms that correlated with DEB025 resistance were identified: H87Q and I91N, both located in the CypA-binding loop of the CA protein of HIV-1. The H87Q change was by far more abundant than I91N. Additional polymorphisms in the CypA-binding loop (positions 86, 91 and 96), as well as in the N-terminal loop of CA were detected in resistant isolates and are assumed to contribute to the degree of resistance. These amino acid changes may modulate the conformation of the CypA-binding loop of CA in such a way that binding and/or isomerase function of CypA are no longer necessary for virus replication. The resistant HIV-1 isolates thus are CypA-independent.

Gallay, Philippe A.; Ptak, Roger G.; Bobardt, Michael D.; Dumont, Jean-Maurice; Vuagniaux, Gregoire; Rosenwirth, Brigitte

2013-01-01

378

Resorcylic Acid lactones as the protein kinase inhibitors , naturally occuring toxins.  

PubMed

Resorcylic acid lactones (RALs) are polyketide natural products with a large macrocyclic ring fused to a resorcylic acid residue. Some RALs contain an ?,?-unsaturated ketone in the macrocycle. So far 46 kinases have been identified that could be potentially targeted by this family of compounds. RALs are of interest for their modulation of growth, and tentatively for the treatment of cancer and neurodegenerative diseases. RALs containing a cis-enone are susceptible to Michael addition reactions with the cysteine residue in the kinase nucleotide binding site, and thus serve as potent inhibitors of several protein kinases - they therefore represent a unique pharmacophore. Notably, this moiety has been shown to be effective also in vivo. This mini-review focuses on the structure and biological effects of the most important RALs, namely zearalenone, hypothemycin, pochonins, lasiodiplodins, aigialomycins, cochlicomycins, zaenols, and paecilomycins. Finally, the review also deals with radicicol, which is a nanomolar inhibitor of the chaperone Hsp90, whose suppression leads to a combinatorial block of cancer-causing pathways. PMID:24070207

Patocka, Jiri; Soukup, Ondrej; Kuca, Kamil

2013-11-01

379

Laboratory studies using naturally occurring "green rust" to aid metal mine water remediation.  

PubMed

Green rust, an Fe (II) and (III) oxyhydroxy salt, can alter the aqueous oxidation state, mobility and toxicity, of inorganic contaminants and thus could have applications in water treatment. This paper discusses a series of stirred, open batch experiments designed to evaluate green rust, and its oxidised equivalent in this context comparing it to a ferrihydrite/goethite 'ochre'. Natural green rust was added to different mine waters as either a wet, reduced material or a dry, partially oxidised material. Experiments showed that the addition of either form accelerated the removal of potentially harmful elements from solution. Within one hour Fe, Al and Cu were completely removed from mine waters with initial concentrations of 80, 70 and 8.5mg/L, respectively, and Zn was reduced from 60 to <5mg/L. These experiments show the potential of green rust in mine water treatment, especially as it is able to remove problematic elements such as Al and Zn. The material is effective even after being dried and mostly oxidised. Changes to the pH and ORP of the mine waters and surface catalysis are the suggested mechanisms of accelerated removal of contaminants. PMID:21497995

Bearcock, Jenny M; Perkins, William T; Pearce, Nicholas J G

2011-03-29

380

Naturally Occurring Changes in Women's Drinking From High School to College and Implications for Sexual Victimization  

PubMed Central

Objective: The current study examined the natural trajectories of alcohol use among women as they transitioned from high school to college, considering changes in drinking for students at initially different levels of drinking. We examined the hypothesis that the association between college drinking and sexual victimization would be stronger for women with less high school drinking experience. Method: Female, college-bound, high school seniors were recruited from the community at the time of graduation (N = 437). Alcohol consumption and sexual victimization were assessed at the time of high school graduation (Time 0 [T0]) and at the end of the first (T1) and second (T2) semesters of college. Results: Abstainers and light drinkers increased alcohol consumption from T0 to T1; however, consumption by those already engaging in heavy episodic drinking remained stable. Consumption did not increase for any group from T1 to T2. As expected, maximum consumption in college was strongly associated with experiencing incapacitated rape or other sexual victimization during the same semester; however, prior drinking experience did not moderate the relationship. Conclusions: Occasions of heavy drinking in college are a significant risk factor for sexual victimization for both experienced and inexperienced drinkers. Findings point toward universal prevention, ideally before college entry, as a strategy for reducing heavy episodic drinking and hence, college sexual victimization.

Testa, Maria; Hoffman, Joseph H.

2012-01-01

381

Trigonelline, a naturally occurring constituent of green coffee beans behind the mutagenic activity of roasted coffee?  

PubMed

Trigonelline and amino acids are natural components in green coffee beans. Model systems mimicking coffee roasting were used to produce heated samples of trigonelline, amino acids and glucose. Trigonelline and amino acids were heated separately or in combinations for 20 min at 250 degrees C. The results of bacteria mutation assays (Salmonella typhimurium strains TA 98, YG 1024 and YG 1029) showed that trigonelline, alone or in combination with most of the single amino acids and mixtures of amino acids, yielded potent mutagenic activity. Of the singly heated compounds, the highest mutagenic activity was found for trigonelline. The mutagenic activity detected with metabolic activation of the heated trigonelline samples indicated that the mutagenic compounds might be amines; however, higher mutagenic activity was found for trigonelline and its combinations without metabolic activation, which suggests that other types of mutagens (direct-acting) were predominant. High-performance liquid chromatographic analysis of some of the heated samples did not reveal the presence of any known mutagenic heterocyclic amine. PMID:9268042

Wu, X; Skog, K; Jägerstad, M

1997-07-14

382

Efficacy of tulathromycin injectable solution for the treatment of naturally occurring Swine respiratory disease.  

PubMed

Tulathromycin, a novel triamilide antimicrobial, was evaluated for treatment of swine respiratory disease (SRD) in field efficacy studies involving 720 pigs in six North American swine herds. In each study, feeder pigs with clinical SRD were randomly assigned in equal numbers to a group treated with tulathromycin given as a single injection at 2.5 mg/kg of body weight or to a saline-treated control group. Four of the studies included a third group treated with ceftiofur sodium for 3 consecutive days at 3 mg/kg of body weight. Pigs were treated on day 0 and evaluated for treatment response on day 7. In each study, 10 or more nontreated pigs and saline-treated pigs that did not respond to treatment underwent necropsies to obtain lung samples that were evaluated for SRD pathogens. The overall cure rate was 46.4% for saline-treated pigs, 71.1% for tulathromycin-treated pigs, and 63.1% for ceftiofur-treated pigs. The cure rate for tulathromycin-treated pigs was significantly higher than for saline-treated pigs (P = .0116). Mortality from SRD occurred in 24 control pigs, seven tulathromycin-treated pigs, and one ceftiofur-treated pig. The mortality rate was significantly lower for both the tulathromycin- and ceftiofur-treated pigs compared with those treated with saline (P = .0148 and P = .0195, respectively). Actinobacillus pleuropneumoniae, Pasteurella multocida, Haemophilus parasuis, and Mycoplasma hyopneumoniae, bacteria commonly associated with SRD, were isolated from SRD-affected pigs. Under field conditions, tulathromycin injectable solution given as a single IM dose of 2.5 mg/kg of body weight was safe and effective in the treatment of SRD. PMID:16094568

Nutsch, Robert G; Hart, Fred J; Rooney, Kathleen A; Weigel, Daniel J; Kilgore, W Randal; Skogerboe, Terry L

2005-01-01

383

Naturally occurring NS gene variants in an avian influenza virus isolate.  

PubMed

The A/Turkey/Wisconsin/68 (H5N9) isolate of avian influenza (AI) consists of two virus populations which have different NS genes and differ in their biological responses in chicken embryos. They were classified as being either rapidly embryo-lethal (REL) or slowly embryo-lethal (SEL), (Avian Dis., 33 (1989) 695-706). In this study, sequence analysis identified only two nucleotide differences between the two NS genes, creating single amino acid differences in both the NS1 and the NS2 protein. The difference in the NS1 protein appears to be neutral, while the differences in the NS2 places a phenylalanine at position 48. This amino acid has not been previously demonstrated at this position in an NS2 sequence and its presence results in a distinct hydrophobic shift in the region. The sequence specifying the phenylalanine also creates an EcoRI site in the cDNA of the REL NS gene. Analysis of several clones showed that this site appears to co-segregate with the REL characteristic. Molecular differences between the two NS gene variants were reflected by differences in the kinetics of early protein synthesis in infected cells. In particular, the NS2 protein is in higher concentration (relative to the NS1) in SEL-infected cells than in REL-infected cells. No differences were detectable, however, in the rates of viral replication, either in cell culture or in embryos. Also, the REL or SEL rate was established early during infection of the embryo and could not be competed out by the other variant population 3 h after inoculation. Thus, these two natural NS gene variants appear to specify early differences which influence the time of death of an infected embryo but the differences do not appear to influence virus replication. PMID:1320795

Perdue, M L

1992-05-01

384

Collection, isolation and enrichment of naturally occurring magnetotactic bacteria from the environment.  

PubMed

Magnetotactic bacteria (MTB) are aquatic microorganisms that were first notably described in 1975 from sediment samples collected in salt marshes of Massachusetts (USA). Since then MTB have been discovered in stratified water- and sediment-columns from all over the world. One feature common to all MTB is that they contain magnetosomes, which are intracellular, membrane-bound magnetic nanocrystals of magnetite (Fe3O4) and/or greigite (Fe3S4) or both. In the Northern hemisphere, MTB are typically attracted to the south end of a bar magnet, while in the Southern hemisphere they are usually attracted to the north end of a magnet. This property can be exploited when trying to isolate MTB from environmental samples. One of the most common ways to enrich MTB is to use a clear plastic container to collect sediment and water from a natural source, such as a freshwater pond. In the Northern hemisphere, the south end of a bar magnet is placed against the outside of the container just above the sediment at the sediment-water interface. After some time, the bacteria can be removed from the inside of the container near the magnet with a pipette and then enriched further by using a capillary racetrack and a magnet. Once enriched, the bacteria can be placed on a microscope slide using a hanging drop method and observed in a light microscope or deposited onto a copper grid and observed using transmission electron microscopy (TEM). Using this method, isolated MTB may be studied microscopically to determine characteristics such as swimming behavior, type and number of flagella, cell morphology of the cells, shape of the magnetic crystals, number of magnetosomes, number of magnetosome chains in each cell, composition of the nanomineral crystals, and presence of intracellular vacuoles. PMID:23183960

Oestreicher, Zachery; Lower, Steven K; Lin, Wei; Lower, Brian H

2012-11-15

385

Use of Sulphur and Boron Isotopes to Identify Natural Gas Processing Emissions Sources  

NASA Astrophysics Data System (ADS)

Natural gas processing results in the emission of large amounts of gaseous pollutants as a result of planned and / or emergency flaring, sulphur incineration, and in the course of normal operation. Since many gas plants often contribute to the same air shed, it is not possible to conclusively determine the sources, amounts, and characteristics of pollution from a particular processing facility using traditional methods. However, sulphur isotopes have proven useful in the apportionment of sources of atmospheric sulphate (Norman et al., 1999), and boron isotopes have been shown to be of use in tracing coal contamination through groundwater (Davidson and Bassett, 1993). In this study, both sulphur and boron isotopes have been measured at source, receptor, and control sites, and, if emissions prove to be sufficiently distinct isotopically, they will be used to identify and apportion emissions downwind. Sulphur is present in natural gas as hydrogen sulphide (H2S), which is combusted to sulphur dioxide (SO2) prior to its release to the atmosphere, while boron is present both in hydrocarbon deposits as well as in any water used in the process. Little is known about the isotopic abundance variations of boron in hydrocarbon reservoirs, but Krouse (1991) has shown that the sulphur isotope composition of H2S in reservoirs varies according to both the concentration and the method of formation of H2S. As a result, gas plants processing gas from different reservoirs are expected to produce emissions with unique isotopic compositions. Samples were collected using a high-volume air sampler placed directly downwind of several gas plants, as well as at a receptor site and a control site. Aerosol sulphate and boron were collected on quartz fibre filters, while SO2 was collected on potassium hydroxide-impregnated cellulose filters. Solid sulphur samples were taken from those plants that process sulphur in order to compare the isotopic composition with atmospheric measurements. A method was developed to extract and concentrate boron for isotope analysis. Isotopic composition and concentrations of both sulphur and boron were measured in order to determine whether emissions have distinct sulphur and/or boron isotopic compositions. Preliminary results of SO2 and solid sulphur analysis show values that range from +3 to +30 \\permil.

Bradley, C. E.; Norman, A.; Wieser, M. E.

2003-12-01

386

Naturally occurring and stress induced tubular structures from mammalian cells, a survival mechanism  

PubMed Central

Background Tubular shaped mammalian cells in response to dehydration have not been previously reported. This may be due to the invisibility of these cells in aqueous solution, and because sugars and salts added to the cell culture for manipulation of the osmotic conditions inhibit transformation of normal cells into tubular shaped structures. Results We report the transformation of normal spherical mammalian cells into tubular shaped structures in response to stress. We have termed these transformed structures 'straw cells' which we have associated with a variety of human tissue types, including fresh, post mortem and frozen lung, liver, skin, and heart. We have also documented the presence of straw cells in bovine brain and prostate tissues of mice. The number of straw cells in heart, lung tissues, and collapsed straw cells in urine increases with the age of the mammal. Straw cells were also reproduced in vitro from human cancer cells (THP1, CACO2, and MCF7) and mouse stem cells (D1 and adipose D1) by dehydrating cultured cells. The tubular center of the straw cells is much smaller than the original cell; houses condensed organelles and have filamentous extensions that are covered with microscopic hair-like structures and circular openings. When rehydrated, the filaments uptake water rapidly. The straw cell walls, have a range of 120 nm to 200 nm and are composed of sulfated-glucose polymers and glycosylated acidic proteins. The transformation from normal cell to straw cells takes 5 to 8 hr in open-air. This process is characterized by an increase in metabolic activity. When rehydrated, the straw cells regain their normal spherical shape and begin to divide in 10 to 15 days. Like various types of microbial spores, straw cells are resistant to harsh environmental conditions such as UV-C radiation. Conclusion Straw cells are specialized cellular structures and not artifacts from spontaneous polymerization, which are generated in response to stress conditions, like dehydration. The disintegrative, mobile, disruptive and ubiquitous nature of straw cells makes this a possible physiological process that may be involved in human health, longevity, and various types of diseases such as cancer.

Wu, Yonnie; Laughlin, Richard C; Henry, David C; Krueger, Darryl E; Hudson, JoAn S; Kuan, Cheng-Yi; He, Jian; Reppert, Jason; Tomkins, Jeffrey P

2007-01-01

387

Stable Isotopic and Hydrogeochemical Characteristics of Natural Attenuation in a Municipal Landfill  

Microsoft Academic Search

The goal of the study is to know the mechanisms of groundwater contamination by leachate from a municipal landfill located at Busan city, Korea. This study illustrates that isotopic and major ions chemistry of groundwater and leachate is to provide redox, ion exchange and precipitation reactions occurring in the aquifer. The multivariate statistical methods were also adopted to investigate of

K. Ko; K. Lee

2008-01-01

388

Natural variations in calcium isotope composition as a monitor of bone mineral balance in humans.  

NASA Astrophysics Data System (ADS)

The skeleton is the largest reservoir of calcium in the human body and is responsible for the short term control of blood levels of this element. Accurate measurement of changes in bone calcium balance is critical to understanding how calcium metabolism responds to physiological and environmental changes and, more specifically, to diagnosing and evaluating the effectiveness of treatments for osteoporosis and other serious calcium-related disorders. It is very difficult to measure bone calcium balance using current techniques, however, because these techniques rely either on separate estimates of bone resorption and formation that are not quantitatively comparable, or on complex and expensive studies of calcium kinetics using administered isotopic tracers. This difficulty is even more apparent and more severe for measurements of short-term changes in bone calcium balance that do not produce detectable changes in bone mineral density. Calcium isotopes may provide a novel means of addressing this problem. The foundation of this isotope application is the ca. 1.3 per mil fractionation of calcium during bone formation, favoring light calcium in the bone. This fractionation results in a steady-state isotopic offset between calcium in bone and calcium in soft tissues, blood and urine. Perturbations to this steady state due to changes in the net formation or resorption of bone should be reflected in changes in the isotopic composition of soft tissues and fluids. Here we present evidence that easily detectable shifts in the natural calcium isotope composition of human urine rapidly reflect changes in bone calcium balance. Urine from subjects in a 17-week bed rest study was analyzed for calcium isotopic composition. Bed rest promotes net resorption of bone, shifting calcium from bone to soft tissues, blood and urine. The calcium isotope composition of patients in this study shifted toward lighter values during bed rest, consistent with net resorption of isotopically-light bone calcium. In contrast, little shift was seen in patients who exercised during bed rest, consistent with the expectation that exercise should inhibit bone resorption. Most intriguingly, an opposite-sense shift was seen in patients who were administered aledronate, a drug which inhibits bone resorption. We hypothesize that these patients entered a state of positive bone mineral balance despite initiation of bed rest. Comparison of isotopic data with measurements of bone mineral density and metabolic markers of bone metabolism confirms that the calcium isotope composition of urine reflects changes in bone mineral balance. Calcium isotope analysis of urine and soft tissues may provide information on bone mineral balance that is in important respects better than that available from other techniques, and illustrates the usefulness of applying geochemical techniques to biomedical problems.

Skulan, J.; Anbar, A.; Thomas, B.; Smith, S.

2004-12-01

389

Contrasts in growth and water sources in co-occurring Mediterranean riparian tree species: Evidence from tree ring isotopes and dendrochronology  

NASA Astrophysics Data System (ADS)

Riparian trees have growth responses to varying water sources that are more subtle than those of their upland counterparts, but differences in water use between co-occurring riparian species are not easily discerned by conventional dendrochronology. While tree ring isotopes have been developed as a useful tool for understanding past climate (temperature and precipitation) at the growth limits for particular species, relatively little research has investigated responses in tree growth in water-rich environments, where co-occurring tree species may express differential adaptation to water availability and shifting water sources. Better understanding of such subtle adaptations will improve predictions of the response of lowland riparian forests to climate changes that manifest as shifts in: regional ground water tables; the spatial/temporal distribution of precipitation; or volumes and timing of streamflow. We use an approach that combines dendrochronology and tree ring isotopes (?18O) to discern the relationships between tree growth and water sources for two contrasting, co-occurring Mediterranean riparian species-- Fraxinus excelsior and Populus nigra. We developed growth time series via two methods (one de-trended for climate) and extracted alpha-cellulose from tree rings to assess relative responses to water stress via ?18O, and we analyzed these data alongside streamflow and precipitation data for the Ain River basin in France. We find that both species exhibit decreased growth during drought years, but F. excelsior demonstrates more consistent annual growth than P. nigra. In contrast, oxygen isotopic values in P. nigra have low interannual variability compared with ?18O in F. excelsior. These differences suggest contrasting patterns of water use by these co-occurring species, wherein F. excelsior functions as an opportunist, scavenging water from the vadose zone where and when it cannot access groundwater. In contrast, the P. nigra demonstrates consistent groundwater usage (consistent with its moniker-obligate phreatophyte) and tends to struggle in drought years. These observations are consistent with ancillary data on rooting depths which show that F. excelsior maintains its roots above the gravel layer, where it can extract soil water from precipitation or overbank flooding. In contrast, P. nigra roots deeply into the phreatic zone without maintaining significant vadose zone roots, and is therefore less adaptable to rapid declines in the water table. These factors suggest, in contrast to prior work, that poplars may be more sensitive to drought than ash trees. Such dynamics in water use between such co-occurring, yet contrasting riparian trees within a riparian floodplain may indicate the response in succession and stand composition to climate changes or major anthropogenic impacts.

Singer, M. B.; Dufour, S.; Stella, J. C.; Piégay, H.; Johnstone, L.; Wilson, R.

2011-12-01

390

The isotopic compositions of molecular nitrogen: implications on their origins in natural gas accumulations  

Microsoft Academic Search

The isotopic compositions of N2 (?15N, ‰, atm) imply the geochemical origins of molecular nitrogen in natural gas accumulations, but the irregular variation of ?15NN2 for most petroliferous basins puzzles scientists. We believe that this is due to multiple origins of N2 which are often mixed together and leads to the irregularities in gas pools. The four petroliferous basins, the

Yuenian Zhu; Buqing Shi; Chaobin Fang

2000-01-01

391

Online Measurement of the Intramolecular Isotopic Composition of Acetate in Natural Porewater Samples  

Microsoft Academic Search

Carbon dioxide and methane are traditionally considered to be the dominant end products of anaerobic metabolism while acetate is thought to be a rapidly consumed intermediate. However, in some settings, recent evidence has grown to suggest that, at least transiently, acetate can be a major metabolic end product. In natural systems, isotopic mass balances can be used to partition the

R. B. Thomas; M. A. Arthur; K. H. Freeman

2006-01-01

392

Natural variations detected in the isotopic composition of copper: possible applications to archaeology and geochemistry  

Microsoft Academic Search

Copper isotopic compositions have been measured both in natural copper minerals from supergene\\/oxidation zones and in some ancient metal artefacts using two different instruments. Measurements were first made using a low temperature thermal ionisation technique with a thermal ionisation mass spectrometer (TIMS); independent data was obtained using a commercial inductively coupled plasma (ICP) magnetic sector multiple collector mass spectrometer. Significant

N. H Gale; A. P Woodhead; Z. A Stos-Gale; A Walder; I Bowen

1999-01-01

393

Carbon Isotope Fractionation Associated with Aerobic Microbial Oxidation of Natural Gas  

Microsoft Academic Search

Carbon stable isotope fractionation associated with the aerobic microbial consumption of propane (C3), n-butane (n-C4) and n-pentane (n-C5) of natural gas were analyzed from the gas seepages of Chianan (Chiayi-Tainan) foothill zone and Hualine hot spring field of Taiwan. The aerobic biologic effect on natural gas is related to subsurface structure, the aerobic and anoxic environment of shallow depth and

Yane-Shih Wang; Chun-Yin Hwang; Jong-chang Wu; Cheng-Lung Kuo

394

Naturally occurring bacteriophages lyse a large proportion of canine and feline uropathogenic Escherichia coli isolates in vitro.  

PubMed

We investigated the feasibility of bacteriophage therapy to combat canine and feline Escherichia coli urinary tract infections (UTIs) by testing the in vitro lytic ability of 40 naturally occurring bacteriophages on 53 uropathogenic E. coli (UPEC). The mean number of UPEC strains lysed by an individual bacteriophage was 21/53 (40%, range 17-72%). In total, 50/53 (94%) of the UPEC strains were killed by one or more of the bacteriophages. Ten bacteriophages lysed 51% of UPEC strains individually and 92% of UPEC strains as a group. Electron microscopy and DNA sequencing of 5 'promising' bacteriophages revealed that 4 bacteriophages belonged to the lytic T4-like genus, while one displayed morphologic similarity to temperate P2-like bacteriophages. Overall, these results indicate that the majority of UPEC are susceptible to lysis by naturally occurring bacteriophages. Thus, bacteriophages show promise as therapeutic agents for treatment of canine and feline E. coli UTIs. PMID:17959211

Freitag, T; Squires, R A; Schmid, J

2007-10-23

395

Spontaneous Correction in the Behavioral Confirmation Process: The Role of Naturally-Occurring Variations in Self-Regulatory Resources  

Microsoft Academic Search

Perceivers' tendencies to correct for expectancy-related biases can be affected by experimental manipulations of goals and cognitive resources. In the current research, we examined the role of naturally-occurring, environmentally-produced variations in self-regulatory resources, represented by the time of semester in which college students participated. A pilot study established the association between time of semester and self-regulatory resources. Using a simulated

Mario P. Casa de Calvo; Darcy A. Reich

2007-01-01

396

Detection of Activated Caspase3 by a Cleavage Site-Directed Antiserum during Naturally Occurring DRG Neurons Apoptosis  

Microsoft Academic Search

We prepared a cleavage site-directed antiserum against Caspase-3 (anti-p20\\/17), which reacts with the p20\\/17 fragment (p20\\/17) activated by cleavage but not proCaspase-3 (p32), and examined the relationship between the activation of Caspase-3 and apoptosis. We identified p20\\/17-positive cells where cell death occurs naturally: interdigits of the forelimbs, small intestine epithelium, thymus, trigeminal ganglia, and dorsal root ganglia of mouse embryos.

Yoriko Kouroku; Koko Urase; Eriko Fujita; Kyoko Isahara; Yoshiyuki Ohsawa; Yasuo Uchiyama; Mariko Y. Momoi; Takashi Momoi

1998-01-01

397

Physiological quantities of naturally occurring steroid hormones (androgens and progestogens), precursors and metabolites in beef of differing sexual origin  

Microsoft Academic Search

The present investigation gives a comprehensive overview of the naturally occurring steroid hormones, their precursors and\\u000a metabolites in the food-stuff beef. Thus, comparison values have been established using modern analytical techniques for the\\u000a evaluation of the alimentary administration of hormones via beef and for the evaluation of detected residues. The utilization\\u000a of hormone patterns in meat samples enables the sexual

Mathias Hartwig; Sonja Hartmann; Hans Steinhart

1997-01-01

398

Laboratory methods for evaluating migrated high molecular weight hydrocarbons in marine sediments at naturally occurring oil seeps  

Microsoft Academic Search

A laboratory study has been conducted to determine the best methods for the detection of C10–C40 hydrocarbons at naturally occurring oil seeps in marine sediments. The results indicate that a commercially available method using n-C6 to extract sediments and gas chromatography–flame ionization detection (GC–FID) to screen the resulting extract is effective at recognizing the presence of migrated hydrocarbons at concentrations

Graham A. Logan; Michael A. Abrams; Nicola F. Dahdah; Emmanuelle Grosjean

2009-01-01

399

The naturally occurring silent invertase structural gene suc2° contains an amber stop codon that is occasionally read through  

Microsoft Academic Search

The yeast invertase structural gene SUC2 has two naturally occurring alleles, the active one and a silent allele called suc2°. Strains carrying suc2° are unable to ferment sucrose and do not show detectable invertase activity. We have isolated suc2° and found an amber codon at position 232 of 532 amino acids. However, transformants carrying suc2° on a multicopy plasmid were

Daniel Gozalbo; Stefan Hohmann

1989-01-01

400

Inhibitory effect of ODN, a naturally occurring processing product of diazepam binding inhibitor, on secretagogues-induced insulin secretion  

Microsoft Academic Search

Diazepam binding inhibitor (DBI1–86) is a peptide that is present in large amounts in the intestine and pancreas and which inhibits glucose-stimulated insulin release from both perfused pancreas and isolated islets in low nanomolar concentrations. Here, DBI33–50 (also known as ODN, octadecaneuropeptide), one of the naturally occurring processing products of DBI1–86, and certain synthetic modified derivatives, have been shown to

P. De Stefanis; F. Impagnatiello; A. Berkovich; A. Guidotti

1995-01-01

401

Background Characterisation Study of Naturally Occurring Acid Rock Drainage in the Sangre De Cristo Mountains, Taos County, New Mexico  

Microsoft Academic Search

A background characterisation study was carried out in the Sangre de Cristo mountains, New Mexico, to: 1. quantify naturally occurring contaminant loads from mineralised areas; 2. define site-specific background concentrations; and 3. to determine key factors controlling spatial and temporal variations in contaminant concentrations. The study included a comprehensive sampling and testing program (paste pH\\/EC, ABA, leach extraction tests) of

S Shaw; C Wels; A Robertson; S Fortin; B Walker

2003-01-01

402

Elevated Appraisals of the Negative Impact of Naturally Occurring Life Events: A Risk Factor for Depressive and Anxiety Disorders  

Microsoft Academic Search

The tendency to appraise naturally occurring life events (LEs) as having high negative impact may be a predisposing factor\\u000a for the development of depression and anxiety disorders. In the current study, appraisals of the negative impact of recent\\u000a LEs were examined in relationship to depressive and anxiety disorders in a sample of 653 adolescents who were administered\\u000a diagnostic and life

Emmanuel Peter Espejo; Constance Hammen; Patricia A. Brennan

403

Water quality in the vicinity of Mosquito Creek Lake, Trumbull County, Ohio, in relation to the chemistry of locally occurring oil, natural gas, and brine  

USGS Publications Warehouse

Environmental samples collected in the Mosquito Creek Lake area were used to characterize water quality in relation to the chemistry of locally occurring oil, natural gas, and brine and to establish baseline water quality. Mosquito Creek Lake (a manmade reservoir) and the shallow bedrock aquifers near the lake are major sources of potable water in central Trumbull County. The city of Warren relies on the lake as a sole source of potable water. Some of the lake bottom may be in direct hydraulic connection with the underlying aquifers. The city of Cortland, along the southeastern shore of the lake, relies on the Cussewago Sandstone aquifer as a sole source of potable water. This aquifer subcrops beneath the glacio-fluvial sediments that underlie the lake. Nearly all residential homes around the lake, with the exception of homes in the city of Cortland, rely on domestic supply wells as a source of potable water. Oil and natural gas exploration and production have been ongoing in the Mosquito Creek Lakearea since the discovery of the historic Mecca Oil Pool in the Mississippian Berea and Cussewago Sandstones in 1860. Since the late 1970' s, the major drilling objective and zone of production is the Lower Silurian Clinton sandstone. The oil and natural gas resources of the Mosquito Creek Lake area, including reservoir pressure, production history, and engineering and abandonment practices are described in this report. The chemical and isotopic characteristics of the historic Mecca oil and natural gas are very different than those of the Clinton sandstone oil and natural gas. Gas chromatograms show that Mecca oil samples are extensively altered by biodegradation, whereas Clinton sandstone oils are not. Extensive alteration of Mecca oil is consistent with their occurrence at very shallow depths (less than 100 ft below land surface) where microbial activity can affect their composition. Also, the carbon-isotope composition of dissolved methane gas from Berea and Cussewago Sandstone water samples indicates that the gas is microbially generated, whereas the Clinton sandstone gases are thermogenically generated. Methane gas, in addition to crude oil, occurs naturally in the shallow Berea and Cussewago Sandstone aquifers in the Mosquito Creek Lake area and concentrations of dissolved methane are significant in the city of Cortland public-supply wells and in the domestic-supply wells near the southern shore of the lake. Water associated with oil and gas in the Clinton sandstone is a brine with high concentrations of chloride. Water from the Berea and Cussewago Sandstones, however, is fresh and potable. The contrasting geochemical characteristics are important for addressing water-quality issues that relate to oil and natural gas development in the Mosquito Creek area. A reexamination of the geologic framework and results of a subsurface-gas survey show that crude oil in the historic Mecca Oil Pool probably does not seep into Mosquito Creek Lake. Environmental samples show no evidence of any measurable release of oil, gas, or brine from the deeper Clinton sandstone oil and gas wells to the shallow aquifers, the lake, or lake tributaries. Brine is not associated with the hydrocarbons in the shallow Berea-Cussewago aquifer system and therefore cannot be a source of brine contamination. A mixing diagram constructed for dissolved bromide and chloride in surface water and water-supply wells shows no demonstrable mixing of these water resources with brine from the Clinton sandstone. There is some notable salinity in surface waters; however, the water is bromide poor, and a mixing diagram indicates that some local ground waters are influenced by halite solutions, presumably derived from leaching of road salt or from septic effluent.

Barton, G. J.; Burruss, R. C.; Ryder, R. T.

1998-01-01

404

Naturally occurring graphite cones  

Microsoft Academic Search

Carbon, boron nitride, and other materials that form nanotubes are also able to form conical shapes. Even though the potential applications of cone arrays as electron emitters and other devices are very promising, understanding of their structure and formation mechanisms is still very limited compared to nanotubes and other carbon structures. Moreover, the cones have only been synthesized in a

John A. Jaszczak; George W. Robinson; Svetlana Dimovski; Yury Gogotsi

2003-01-01

405

Dual infection and superinfection inhibition of epithelial skin cells by two alphaherpesviruses co-occur in the natural host.  

PubMed

Hosts can be infected with multiple herpesviruses, known as superinfection; however, superinfection of cells is rare due to the phenomenon known as superinfection inhibition. It is believed that dual infection of cells occurs in nature, based on studies examining genetic exchange between homologous alphaherpesviruses in the host, but to date, this has not been directly shown in a natural model. In this report, gallid herpesvirus 2 (GaHV-2), better known as Marek's disease virus (MDV), was used in its natural host, the chicken, to determine whether two homologous alphaherpesviruses can infect the same cells in vivo. MDV shares close similarities with the human alphaherpesvirus, varicella zoster virus (VZV), with respect to replication in the skin and exit from the host. Recombinant MDVs were generated that express either the enhanced GFP (eGFP) or monomeric RFP (mRFP) fused to the UL47 (VP13/14) herpesvirus tegument protein. These viruses exhibited no alteration in pathogenic potential and expressed abundant UL47-eGFP or -mRFP in feather follicle epithelial cells in vivo. Using laser scanning confocal microscopy, it was evident that these two similar, but distinguishable, viruses were able to replicate within the same cells of their natural host. Evidence of superinfection inhibition was also observed. These results have important implications for two reasons. First, these results show that during natural infection, both dual infection of cells and superinfection inhibition can co-occur at the cellular level. Secondly, vaccination against MDV with homologous alphaherpesvirus like attenuated GaHV-2, or non-oncogenic GaHV-3 or meleagrid herpesvirus (MeHV-1) has driven the virus to greater virulence and these results implicate the potential for genetic exchange between homologous avian alphaherpesviruses that could drive increased virulence. Because the live attenuated varicella vaccine is currently being administered to children, who in turn could be superinfected by wild-type VZV, this could potentiate recombination events of VZV as well. PMID:22629393

Jarosinski, Keith W

2012-05-21

406

Pristanic acid and phytanic acid: naturally occurring ligands for the nuclear receptor peroxisome proliferator-activated receptor alpha.  

PubMed

Phytanic acid and pristanic acid are branched-chain fatty acids, present at micromolar concentrations in the plasma of healthy individuals. Here we show that both phytanic acid and pristanic acid activate the peroxisome proliferator-activated receptor alpha (PPARalpha) in a concentration-dependent manner. Activation is observed via the ligand-binding domain of PPARalpha as well as via a PPAR response element (PPRE). Via the PPRE significant induction is found with both phytanic acid and pristanic acid at concentrations of 3 and 1 microM, respectively. The trans-activation of PPARdelta and PPARgamma by these two ligands is negligible. Besides PPARalpha, phytanic acid also trans-activates all three retinoic X receptor subtypes in a concentration-dependent manner. In primary human fibroblasts, deficient in phytanic acid alpha-oxidation, trans-activation through PPARalpha by phytanic acid is observed. This clearly demonstrates that phytanic acid itself, and not only its metabolite, pristanic acid, is a true physiological ligand for PPARalpha. Because induction of PPARalpha occurs at ligand concentrations comparable to the levels found for phytanic acid and pristanic acid in human plasma, these fatty acids should be seen as naturally occurring ligands for PPARalpha. These results demonstrate that both pristanic acid and phytanic acid are naturally occurring ligands for PPARalpha, which are present at physiological concentrations. PMID:11060349

Zomer, A W; van Der Burg, B; Jansen, G A; Wanders, R J; Poll-The, B T; van Der Saag, P T

2000-11-01

407

Naturally Occurring Radionuclides of Ash Produced by Coal Combustion. The Case of the Kardia Mine in Northern Greece  

NASA Astrophysics Data System (ADS)

West Macedonia Lignite Center (WMLC), located in Northwest Greece, releases into the atmosphere about 21,400 tons/year of fly ash through the stacks of four coal fired plants. The lignite ash contains naturally occurring radionuclides, which are deposited on the WMLC basin. This work investigates the natural radioactivity of twenty six ash samples, laboratory produced from combustion of lignite, which was sampled perpendicularly to the benches of the Kardia mine. The concentrations of radionuclides 40K, 235U, 238U, 226Ra, 228Ra and 232Th, were measured spectroscopically and found round one order of magnitude as high as those of lignite. Subsequently the Radionuclide Partitioning Coefficients of radionuclides were calculated and it was found that they are higher for 232Th, 228Ra and 40K, because the latter have closer affinity with the inorganic matrix of lignite. During combustion up to one third of the naturally occurring radioisotopes escape from the solid phase into the flue gases. With comparison to relative global data, the investigated ash has been found to have relatively high radioactivity, but the emissions of the WMLC radionuclides contribute only 0.03% to the mean annual absorbed dose.

Fotakis, M.; Tsikritzis, L.; Tzimkas, N.; Kolovos, N.; Tsikritzi, R.

2008-08-01

408

The carbon isotopic composition of catalytic gas: A comparative analysis with natural gas  

SciTech Connect

Tee idea that natural gas is the thermal product of organic decomposition has persisted for over half a century. Crude oil is thought to be an important source of gas, cracking to wet gas above 150 C, and dry gas above 200 C. But there is little evidence to support this view. For example, crude oil is proving to be more stable than previously thought and projected to remain intact over geologic time at typical reservoir temperature. Moreover, when oil does crack, the products do not resemble natural gas. Oil to gas could be catalytic, however, promoted by the transition metals in carbonaceous sediments. This would explain the low temperatures at which natural gas forms, and the high amounts of methane. This idea gained support recently when the natural progression of oil to dry gas was duplicated in the laboratory catalytically. The authors report here the isotopic composition of catalytic gas generated from crude oil and pure hydrocarbons between 150 and 200 C. {delta}{sup 13}C for C{sub 1} through C{sub 5} was linear with 1/n (n = carbon number) in accordance with theory and typically seen in natural gases. Over extended reaction, isobutane and isopentane remained lighter than their respective normal isomers and the isotopic differentials were constant as all isomers became heavier over time. Catalytic methane, initially {minus}51.87{per_thousand} (oil = {minus}22.5{per_thousand}), progressed to a final composition of {minus}26.94{per_thousand}, similar to the maturity trend seen in natural gases: {minus}50{per_thousand} to {minus}20{per_thousand}. Catalytic gas is thus identical to natural gas in molecular and isotopic composition adding further support to the view that catalysis by transition metals may be a significant source of natural gas.

Mango, F.D. [Rice Univ., Houston, TX (United States). Dept. of Chemical Engineering; Elrod, L.W. [Houston Advanced Research Center, The Woodlands, TX (United States). Geotechnology Research Inst.

1999-04-01

409

The carbon isotopic composition of catalytic gas: A comparative analysis with natural gas  

NASA Astrophysics Data System (ADS)

The idea that natural gas is the thermal product of organic decomposition has persisted for over half a century. Crude oil is thought to be an important source of gas, cracking to wet gas above 150°C, and dry gas above 200°C. But there is little evidence to support this view. For example, crude oil is proving to be more stable than previously thought and projected to remain intact over geologic time at typical reservoir temperatures. Moreover, when oil does crack, the products do not resemble natural gas. Oil to gas could be catalytic, however, promoted by the transition metals in carbonaceous sediments. This would explain the low temperatures at which natural gas forms, and the high amounts of methane. This idea gained support recently when the natural progression of oil to dry gas was duplicated in the laboratory catalytically. We report here the isotopic composition of catalytic gas generated from crude oil and pure hydrocarbons between 150 and 200°C. ? 13C for C 1 through C 5 was linear with 1/ n ( n = carbon number) in accordance with theory and typically seen in natural gases. Over extended reaction, isobutane and isopentane remained lighter than their respective normal isomers and the isotopic differentials were constant as all isomers became heavier over time. Catalytic methane, initially -51.87‰ (oil = -22.5‰), progressed to a final composition of -26.94‰, similar to the maturity trend seen in natural gases: -50‰ to -20‰. Catalytic gas is thus identical to natural gas in molecular and isotopic composition adding further support to the view that catalysis by transition metals may be a significant source of natural gas.

Mango, Frank D.; Elrod, L. W.

1999-04-01

410

Survey of Natural Cadmium Isotope Fractionation by Double Spike Thermal Ionisation Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Wombacher et al. (2003) have shown recently that natural Cd isotope fractionations in terrestrial materials are extremely limited (~100 ppm/amu or less). Thus, excellent external precision is absolutely paramount if Cd isotope fractionations are to be adequately quantified. Here we present a new high-precision double spike (DS) technique for Cd isotopes in which the Cd is measured by thermal ionisation mass spectrometry (TIMS, ThermoElectron Triton), which draws on the pioneering work of Rosman et al. (1980). We observe pronounced anomalous odd-even isotope mass bias during TIMS measurement of Cd with silica gel activator, and avoid such effects by utilizing even isotopes of Cd only. The double spike and its composition were carefully optimized (cf. Galer, 1999), and the "natural" Cd isotope fractionation is expressed as the relative deviations in ^{112}Cd/^{110}Cd (in parts per 104) from our JMC Cd shelf standard. The external reproducibility for 100 ng loads of double-spiked JMC Cd shelf is ± 0.14 ?^{112/110}Cd (2SD, N=57) -- i.e. ±7 ppm/amu -- which is a factor of 4 to 10 times better than that reported in published studies using MC-ICP-MS techniques (e.g. Wombacher et al., 2003; Cloquet et al., 2005). The DS-TIMS method offers further benefits in terms of superior sensitivity, while Cd abundances are obtained as a biproduct by isotope dilution. We have analyzed ?^{112/110}Cd in over sixty samples from different terrestrial reservoirs and environments in order to delimit the extent of natural isotope fractionation of Cd. Most samples were duplicated or triplicated. To facilitate inter-lab comparison, our measured ?^{112/110}Cd for the standards "Münster Cd" and BAM-1012 averaged +21.46 and -7.42, respectively. On the whole, our study confirms the conclusions of Wombacher et al. (2003) that Cd isotope variations in terrestrial materials are limited -- nearly all samples fall within the range -1.0 to +1.0 in ?^{112/110}Cd. Nevertheless, we are able for the first time to resolve clearly differences far outside of analytical error. Analyses of 31 hydrogenous Fe-Mn deposits (and phosphorites) worldwide range from -0.6 to +2.0; those from the Indian and Circum- Antarctic Oceans lie at ~0, whíle Pacific and Atlantic samples generally having positive values. We suggest these differences reflect different rates of vertical inorganic scavenging and remineralization. Oceanic basalts (MORB, Hawaii) and continental loess samples generally have negative ?^{112/110}Cd (-1.2 to -0.5) which may imply that the bulk silicate Earth has a mildly negative value relative to our Cd standard. Major sphalerite deposits worldwide are clustered between -1.0 and 0 suggesting that the mechanisms of ore deposit formation do not result in large isotopic fractionations of Cd. Ocean floor hydrothermal sulphide and Fe-Mn deposits mostly cluster around -0.5, but a few of the sulphides exhibit large variations -- as fractionated as -3.0 to +1.0. Overall, natural variations in ?^{112/110}Cd appear to be quite limited -- and are now resolvable -- but are dwarfed by the extreme Cd isotope fractionations found in meteorites (Rosman et al., 1980; Wombacher et al., 2003) and anthropogenic Cd (Cloquet et al., 2005). References: Cloquet C. et al. (2005), Geostand. Geoanal. Res. 1, 95-106; Galer S.J.G. (1999), Chem. Geol. 157, 255-274; Rosman K.J.R. et al. (1980), Geochem. J. 14, 269-277; Wombacher F. et al. (2003), Geochim. Cosmochim. Acta 67, 4639-4654.

Schmitt, A.; Galer, S. J.; Abouchami, W.

2006-12-01

411

In vitro activity of Brazilian medicinal plants, naturally occurring naphthoquinones and their analogues, against methicillin-resistant Staphylococcus aureus.  

PubMed

Fourteen extracts from Brazilian traditional medicinal plants used to treat infectious diseases were used to look for potential antimicrobial activity against multiresistant bacteria of medical importance. Staphylococcus aureus strains were susceptible to extracts of Punica granatum and Tabebuia avellanedae. The minimum inhibitory concentrations (MICs) of the total extracts and of additional fractions of these plants were determined by employing strains of methicillin-resistant (MRSA) and -sensitive (MSSA) S. aureus, including isolates of the PFGE clone A, which is prevalent in Brazil and two ATCC reference strains. A mixture of ellagitannins isolated from P. granatum and two naphthoquinones isolated from T. avellanedae demonstrated antibacterial activity against all S. aureus strains tested. Semi-synthetic furanonaphthoquinones (FNQs) showed lower MICs than those exhibited by natural occurring naphthoquinones. The results indicate that these natural products can be effective potential candidates for the development of new strategies to treat MRSA infections. PMID:12636992

Machado, T B; Pinto, A V; Pinto, M C F R; Leal, I C R; Silva, M G; Amaral, A C F; Kuster, R M; Netto-dosSantos, K R

2003-03-01

412

Correlation of natural gas by use of carbon isotopic distribution between hydrocarbon components  

SciTech Connect

The natural distribution of carbon isotopes between hydrocarbon gas components is used for (1) determining a gas's maturity, (2) correlating a reservoired gas to its source, (3) correlating one reservoired gas with another, and (4) recognizing gas mixtures. Calculated separations of carbon isotopes between the normal alkane components of a natural gas have been related to source rock maturity by use of a single, continuous diagram, independent of source type. Actual data from a wide variety of geologic settings and geologic ages confirm this relationship and demonstrate its applicability to the source rock Levels of Organic Metamorphism ranging form 8 to 13, covering the entire range of oil and wet-gas generation. At greater maturities, the wet-gas components are found to undergo thermal degradation, losing their usefulness for correlation. Three examples showing indigenous gas (west Texas), non-indigenous gas (Gippsland basin, Australia), and gas mixtures from multiple sources (southeastern Alberta) illustrate exploration applications.

James, A.T.

1983-07-01

413

Present State of the avogadro constant determination from silicon Crystals with natural isotopic compositions  

Microsoft Academic Search

A determination of the Avogadro constant from two selected silicon single-crystals with natural isotopic compositions is described. The density, molar mass, and lattice spacing of the two crystals were measured at NMIJ, PTB, IRMM, IMGC, and NIST. When all the data are combined, they lead to a value of the Avogadro constant of 6.022 1353 (18)×1023 mol-1 with a relative

Kenichi Fujii; Atsushi Waseda; Naoki Kuramoto; Shigeki Mizushima; Peter Becker; Horst Bettin; Arnold Nicolaus; Ulrich Kuetgens; Staf Valkiers; Philip Taylor; Paul De Bievre; Giovanni Mana; Enrico Massa; Richard Matyi; Ernest Kessler; Michael Hanke

2005-01-01

414

Distribution of injected technetium(99m)-labeled mesenchymal stem cells in horses with naturally occurring tendinopathy.  

PubMed

This study aimed to investigate immediate cell survival and distribution following different administration routes of mesenchymal stem cells (MSCs) into naturally occurring tendon injuries. Ten million MSCs, labeled with technetium-99m hexamethylpropyleneamine oxime, were implanted into 13 horses with naturally occurring tendon or ligament injuries intra-lesionally, intravenously and by regional perfusion, and traced for up to 48?h using planar gamma scintigraphy. Labeling efficiencies varied between 1.8% and 18.5% (mean 9.3%). Cells were retained in the damaged area after intra-lesional administration but only 24% of cells were still present within the tendon after 24?h. After intravenous injection, cells largely distributed to the lung fields, with no detectable cells in the tendon lesions. Significant labeling of the tendon lesions was observed in 11/12 horses following regional perfusion but at a lower level to intra-lesional injection. The highest cell numbers were retained after intra-lesional injection, although with considerable cell loss, while regional perfusion may be a viable alternative for MSC delivery. Cells did not "home" to damaged tendon in large numbers after intravenous administration. Cells were detected in the lungs most frequently after intravascular administration, although with no adverse effects. Low cell retention has important implications for designing effective clinical therapies for human clinical use. PMID:23508674

Becerra, Patricia; Valdés Vázquez, Miguel A; Dudhia, Jayesh; Fiske-Jackson, Andrew R; Neves, Francisco; Hartman, Neil G; Smith, Roger K W

2013-03-18

415

A Naturally-Occurring Histone Acetyltransferase Inhibitor Derived from Garcinia indica Impairs Newly Acquired and Reactivated Fear Memories  

PubMed Central

The study of the cellular and molecular mechanisms underlying the consolidation and reconsolidation of traumatic fear memories has progressed rapidly in recent years, yet few compounds have emerged that are readily useful in a clinical setting for the treatment of anxiety disorders such as post-traumatic stress disorder (PTSD). Here, we use a combination of biochemical, behavioral, and neurophysiological methods to systematically investigate the ability of garcinol, a naturally-occurring histone acetyltransferase (HAT) inhibitor derived from the rind of the fruit of the Kokum tree (Garcina indica), to disrupt the consolidation and reconsolidation of Pavlovian fear conditioning, a widely studied rodent model of PTSD. We show that local infusion of garcinol into the rat lateral amygdala (LA) impairs the training and retrieval-related acetylation of histone H3 in the LA. Further, we show that either intra-LA or systemic administration of garcinol within a narrow window after either fear conditioning or fear memory retrieval significantly impairs the consolidation and reconsolidation of a Pavlovian fear memory and associated neural plasticity in the LA. Our findings suggest that a naturally-occurring compound derived from the diet that regulates chromatin function may be useful in the treatment of newly acquired or recently reactivated traumatic memories.

Maddox, Stephanie A.; Watts, Casey S.; Doyere, Valerie; Schafe, Glenn E.

2013-01-01

416

A naturally-occurring histone acetyltransferase inhibitor derived from Garcinia indica impairs newly acquired and reactivated fear memories.  

PubMed

The study of the cellular and molecular mechanisms underlying the consolidation and reconsolidation of traumatic fear memories has progressed rapidly in recent years, yet few compounds have emerged that are readily useful in a clinical setting for the treatment of anxiety disorders such as post-traumatic stress disorder (PTSD). Here, we use a combination of biochemical, behavioral, and neurophysiological methods to systematically investigate the ability of garcinol, a naturally-occurring histone acetyltransferase (HAT) inhibitor derived from the rind of the fruit of the Kokum tree (Garcina indica), to disrupt the consolidation and reconsolidation of Pavlovian fear conditioning, a widely studied rodent model of PTSD. We show that local infusion of garcinol into the rat lateral amygdala (LA) impairs the training and retrieval-related acetylation of histone H3 in the LA. Further, we show that either intra-LA or systemic administration of garcinol within a narrow window after either fear conditioning or fear memory retrieval significantly impairs the consolidation and reconsolidation of a Pavlovian fear memory and associated neural plasticity in the LA. Our findings suggest that a naturally-occurring compound derived from the diet that regulates chromatin function may be useful in the treatment of newly acquired or recently reactivated traumatic memories. PMID:23349897

Maddox, Stephanie A; Watts, Casey S; Doyère, Valérie; Schafe, Glenn E

2013-01-21