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At least 577 records · Page 32Linked to original sources
PubMed2000

Characterising phosphorus loss in surface and subsurface hydrological pathways

The magnitude and composition of the phosphorus (P) load transported in surface and subsurface hydrological pathways from a grassland catchment depends on the discharge capacity of the flow route and the frequency with which the pathway operates. Surface runoff is an important pathway for P loss, but this pathway is spatially limited and temporarily confined to high magnitude, high intensity rainfall events. High P concentrations (mean: 1.1 mg TP l(-1)) were recorded, with most P transported in the dissolved fraction. Preferential flow pathways, particularly soil macropores and field drains, are important contributors to the overall P load; most P is transported in the particulate fraction and associated with organic or colloidal P forms. High P concentrations (mean: 1.2 mg TP l(-1)) were recorded in macropore flow in the upper 0-15 cm of a grassland soil, and generally declined with increasing soil depth. On average, P concentrations in drainflow were over six times greater in stormflow compared to baseflow. Stormflow P losses in drainflow were predominantly in the particulate fraction; significant correlation (P < 0.01) was recorded with suspended sediment concentrations in drainflow. Phosphorus concentrations in groundwater were low (< 0.2 mg TP l(-1) at 150 cm), although this pathway may contribute to stream flow for the majority of the year.

Journal Article↗
PubMed2003

Interleukin-1beta does not contribute to genetic strain-based differences in iNOS expression and activity in chicken macrophages.

The expression of IL-1beta and inducible nitric oxide synthase (iNOS) from iNOS hypo (GB2, B(6)B(6)) and hyper (K-strain, B(15)B(15)) responder chickens was examined. Compared to GB2, macrophages from K-strain expressed higher iNOS mRNA as quantitated by reverse transcriptase polymerase (RT-PCR) chain reaction after stimulation with 1 microgram/ml of Escherichia coli (E. coli) lipopolysaccharide (LPS). On the contrary, IL-1beta mRNA expression was comparable between K and GB2 macrophages at 3h post-LPS stimulation but persisted up to 9h only in GB2 macrophages. The LPS-inducible interleukin-1 (IL-1) surface receptor expression, measured by flow cytometry, was higher in GB2 than on K-strain macrophages. Blocking of IL-1 receptor by the anti-IL-1 receptor antibody reduced the LPS-mediated iNOS expression by 50% as quantified by competitive RT-PCR. Furthermore, iNOS activity (nitrite) was also reduced to 50%. However, this magnitude of inhibition was similar in both K and GB2 macrophages. While these observations suggest that IL-1beta is involved in mediating LPS-induced iNOS expression and activity, the differential response of GB1 and K-strain macrophages in terms of LPS-induced iNOS expression and activity is unlikely to be modulated by IL-1beta.

Animals↗
PubMed2002

Differential expression of inducible nitric oxide synthase is associated with differential Toll-like receptor-4 expression in chicken macrophages from different genetic backgrounds.

The purpose of this study was to examine iNOS gene expression and activity in macrophages from different chicken genetic lines against various bacterial LPS. Furthermore, the possible involvement of surface LPS receptors as candidates for differential iNOS gene induction in these genetic lines of chicken was also examined. Sephadex-elicited abdominal macrophages (1 x 10(6)) as well as iNOS hyper-responder macrophages from a transformed chicken macrophage cell line, MQ-NCSU, were exposed to 5 microg/ml LPS from E. coli, Shigella flexneri, Serratia marcensces, and Salmonella typhimurium. Nitrite levels were quantitated in the culture supernatant fractions of macrophages after 24h by the Griess method. The results showed that macrophages from K-strain (B(15)B(15)) (range from two separate trials: 31-89 microM) and MQ-NCSU (22-81 microM) were high responders whereas macrophages from both GB1 (B(13)B(13)) (15-38 microM) and GB2 (B(6)B(6)) (7-15 microM) chickens were low responders against all LPSs used. Northern blot analysis revealed that K-strain macrophages expressed higher intensity of 4.5Kb iNOS mRNA (iNOS/beta-actin ratio) than macrophages from GB2 regardless of the LPS source. To elucidate possible molecular mechanism(s) involved in iNOS gene expression in these two strains of chickens, the constitutive expression of LPS-related macrophage cell surface receptors, CD14, Toll-like receptor-2 (TLR2), and Toll-like receptor-4 (TLR4), was examined via flow cytometry using anti-human CD14, TLR2 and TLR4 antibodies. CD14 surface expression and intensity was not different between macrophages from K-strain or GB2 chickens. In contrast, while the overall percentage of TLR4-positive macrophages was the same (K-strain, trial 1=92%, trial 2=62%; GB2, trial 1=91%, trial 2=64%), the mean fluorescence intensity (MFI), an indicator of receptor number, was significantly higher (P=0.05) in K-strain macrophages (MFI: trial 1=145; trial 2=131) than GB2 macrophages (MFI: trial 1=101; trial 2=98). Furthermore, TLR2 (a previously thought candidate as LPS signaling molecule) positive cell numbers were higher in K-strain than the GB2 macrophages in one of the two trials with no difference in the intensity of TLR2 expression in either trial. These findings suggest that the observed differences in iNOS expression and activity among the K-strain (hyper-responder) and GB2 (hypo-responder) chickens are, at least in part, due to differential expression of TLR4 (an LPS signaling molecule), leading to more intense LPS-mediated activation of K-macrophages.

Animals↗
PubMed2002

Involvement of lipopolysaccharide related receptors and nuclear factor kappa B in differential expression of inducible nitric oxide synthase in chicken macrophages from different genetic backgrounds.

Macrophages from Cornell K-strain chickens (B(15)B(15)) are hyper and from GB2 chickens (B(6)B(6)) are hypo-responders to LPS-mediated inducible NOS (iNOS) expression and activity. The molecular mechanism(s) responsible for this differential expression is not yet fully understood. We have previously reported that macrophages from K (iNOS hyper-responder) and GB2 (iNOS hypo-responder) chickens differ in constitutive expression of TLR4 but not in CD14 molecules. The objectives of the current study was to determine if the iNOS differences between K and GB2 macrophages are possibly due to differential expression of LPS-induced TLR4, CD14 and/or nuclear factor kappa B (NF kappa B). The results showed that Sephadex-elicited, adherence purified K macrophages expressed more inducible TLR4 and CD14 receptors (P<0.05) at 6 and 12h post-LPS stimulation than GB2 macrophages as measured by flow cytometry. In addition, pre-incubation of macrophages from a transformed chicken macrophage cell line, MQ-NCSU, with 50 microg/ml anti-CD14 and anti-TLR4 antibodies significantly reduced where as pre-incubation with 100 microg/ml completely blocked LPS-mediated iNOS activity as measured by nitrite levels. Furthermore, the amount of nuclear bound NF kappa B was found to be significantly greater in K than in GB2 macrophages at 3 min post-LPS stimulation. This nuclear localization of NF kappa B as well as iNOS activity was completely inhibited by pretreatment of macrophages with 50 micro M MG132, a proteosome inhibitor, both in K and GB2 macrophages. Taken together, these findings suggest that a differential and perhaps more stronger LPS-mediated signaling via CD14, TLR4 and NF kappa B is responsible for the heightened iNOS gene induction in K-strain (hyper-responder) macrophages than in GB2 (hypo-responder) chickens.

Animals↗
PubMed1998

Genetic alterations in brain tumors identified by RAPD analysis.

We report the utility of random amplified polymorphic DNA (RAPD) analysis for identifying subtle genomic alterations in meningiomas and gliomas by comparing the DNA band profile of tumor vis-à-vis its constitutional counterpart. Twenty out of the 29 decanucleotide GC-rich random primers utilized for the RAPD analysis of meningiomas revealed alteration(s) in the tumor genome. In gliomas, changes were detected by 16 of the 18 primers. While all the seven meningioma samples exhibited alterations in tumor DNA, changes were evident in 21 of the 24 glioma cases. These alterations in tumor DNA included the loss of a normal band, appearance of a new band and amplification of a pre-existing band. Many primers detected more than one alterations in a given tumor. Our approach, which covers the range from 0.4 to 2 kb, besides detecting a significant number of changes in a spectrum of brain tumors, complements existing DNA fingerprinting methods, such as microsatellite mapping (less than 0.4 kb) and Southern blotting (over 2 kb), for detecting genetic alterations in tumors.

Brain Neoplasms↗
PubMed1994

Milk whey proteins in plasma of sows: variation with physiological state.

The whey proteins alpha-lactalbumin and beta-lactoglobulin have been investigated as potential markers of mammary development in sows by measuring their concentrations in plasma. The whey proteins were isolated from porcine milk by gel filtration, ion-exchange and hydrophobic interaction chromatography, characterized by several criteria and used to raise antibodies. Specific radioimmunoassays were set up for porcine alpha-lactalbumin and beta-lactoglobulin and validated for use in porcine blood and milk. Plasma levels of the whey proteins were measured in sows that were pregnant, suckling litters post partum, weaned abruptly at birth or were pregnant but mastectomized. Both whey proteins showed similar patterns in plasma post partum, falling from a maximum 1 d after parturition to values < 0.02% those in milk by day 4-5 post partum in suckling sows and showing a transient peak associated with early involution before declining to very low concentrations in non-suckling sows. alpha-Lactalbumin was first detected in the last week prepartum, rising markedly in the 3 d before parturition, correlated with rising prolactin (r = 0.986) and falling progesterone (r = -0.998). beta-Lactoglobulin rose much earlier from 5 weeks prepartum, at the time when lobulo-alveolar mammary development is occurring, and correlated (r = 0.929) with oestradiol-17 beta. In mastectomized sows, concentrations of whey proteins in plasma were reduced by 90% or more when compared with intact animals, though following a similar pattern. This study shows that whey protein concentrations in plasma vary with physiological state and reflect aspects of the development of the mammary gland. The very different profiles for alpha-lactalbumin and beta-lactoglobulin prepartum indicate that they are differently controlled.

Animals↗
PubMed1994

Hormonal induction of alpha-lactalbumin and beta-lactoglobulin in cultured mammary explants from pregnant pigs.

Mammary tissue from pigs on days 60, 80, 90, 100 and 100+ (days 106-111) of pregnancy has been cultured in vitro as explants. The total accumulation in tissue and culture medium of the whey proteins alpha-lactalbumin and beta-lactoglobulin has been measured using specific radioimmunoassays. The control, uncultured tissue showed progressive morphological development from sparse, non-secretory epithelial tissue on day 60 to full lobulo-alveolar development with some accumulated secretion from day 100. In uncultured explants beta-lactoglobulin could be detected consistently from day 90 (13 +/- 12 ng/micrograms DNA, n = 4) and alpha-lactalbumin from day 100 (1.3 +/- 0.5 ng/micrograms DNA, n = 11). At all stages of pregnancy, both whey proteins increased markedly during the period of culture (up to 7 d). Stimulation of alpha-lactalbumin appeared to be primarily under prolactin control. Prolactin increased alpha-lactalbumin accumulation to a similar extent alone, or in the presence of insulin and/or corticosterone. The response to prolactin was dose-dependent over the range 0.4-20 nM (10-500 ng/ml). Porcine prolactin was more potent than ovine prolactin. There was no effect of porcine growth hormone and no synergism detected between prolactin and tri-iodothyronine. By contrast, no specific hormonal requirements were established for accumulation of beta-lactoglobulin, which appeared to increase in vitro if tissue remained viable in various combinations of insulin, corticosterone and prolactin. It was not stimulated by growth hormone. There was some indication of a prolactin-sensitive component in longer term cultures after day 4.

Animals↗
PubMed2001

Prolactin-stimulated polymerization of acetyl-coA carboxylase in explants of mid-pregnant rat mammary gland.

Prolactin significantly increased the rate of fatty acid synthesis in explants of mid-pregnant rat mammary gland cultured for 96 h with insulin plus corticosterone. Under these conditions, prolactin increased the specific activity of total acetyl-CoA carboxylase in nuclear-free homogenates of explants by 2.6, and increased the proportion of the enzyme in the active polymeric form from 0.44 to 0.89. Removal of prolactin after 48 h in culture decreased the specific activity of the total enzyme by about half. and decreased the proportion as polymer to 0.52. The results show that prolactin plays a major role in mid-pregnant rat mammary gland in the polymerization which accompanies increased activity of the total enzyme and increased rate of fatty acid synthesis.

Acetyl-CoA Carboxylase↗
PubMed2003

Environmental costs of freshwater eutrophication in England and Wales.

Eutrophication has many known consequences, but there are few data on the environmental and health costs. We developed a new framework of cost categories that assess both social and ecological damage costs and policy response costs. These findings indicate the severe effects of nutrient enrichment and eutrophication on many sectors of the economy. We estimate the damage costs of freshwater eutrophication in England and Wales to be $105-160 million yr(-1) (pound 75.0-114.3 m). The policy response costs are a measure of how much is being spent to address this damage, and these amount to $77 million yr(-1) pound 54.8 m). The damage costs are dominated by seven items each with costs of $15 million yr(-1) or more: reduced value of waterfront dwellings, drinking water treatment costs for nitrogen removal, reduced recreational and amenity value of water bodies, drinking water treatment costs for removal of algal toxins and decomposition products, reduced value of nonpolluted atmosphere, negative ecological effects on biota, and net economic losses from the tourist industry. In common with other environmental problems, it would represent net value (or cost reduction) if damage was prevented at source. A variety of effective economic, regulatory, and administrative policy instruments are available for internalizing these costs.

Costs and Cost Analysis↗
PubMed2005

Experimental and theoretical studies of the C2F4 + O reaction: nonadiabatic reaction mechanism.

In this work, the C(2)F(4)(X(1)A(g)) + O((3)P) reaction was investigated experimentally using molecular beam-threshold ionization mass spectrometry (MB-TIMS). The major primary products were observed to be CF(2)O (+ CF(2)) and CF(3) (+ CFO), with measured approximate yields of % versus %, respectively, neglecting minor products. Furthermore, the lowest-lying triplet and singlet potential energy surfaces for this reaction were constructed theoretically using B3LYP, G2M(UCC, MP2), CBS-QB3, and G3 methods in combination with various basis sets such as 6-31G(d), 6-311+G(3df), and cc-pVDZ. The primary product distribution for the multiwell multichannel reaction was then determined by RRKM statistical rate theory and weak-collision master equation analysis. It was found that the observed production of CF(3) (+ CFO) can only occur on the singlet surface, in parallel with formation of ca. 5 times more CF(2)O(X) + CF(2)(X(1)A(1)). This requires fast intersystem crossing (ISC) from the triplet to the singlet surface at a rate of ca. 4 x 10(12) s(-1). The theoretical calculations combined with the experimental results thus indicate that the yield of triplet CF(2)(ã(3)B(1)) + CF(2)O formed on the triplet surface prior to ISC is < or =35%, whereas singlet CF(2)(X(1)A(1)) + CF(2)O is produced with yield > or =60%, after ISC. In addition, the thermal rate coefficients k(O + C(2)F(4)) in the T = 150-1500 K range were computed using multistate transition state theory and can be expressed as k(T) = 1.67 x 10(-16) x T(1.48) cm(3) molecule(-1) s(-1); they are in agreement with the available experimental results in the T = 298-500 K range.

Journal Article↗