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201.
Effects of Selenium Supplementation on Antioxidant Defense and Glucose Homeostasis in Experimental Diabetes Mellitus 总被引:1,自引:0,他引:1
Erbayraktar Z Yilmaz O Artmann AT Cehreli R Coker C 《Biological trace element research》2007,118(3):217-226
The objective of this study was to investigate the effects of different forms of Se supplementation on the antioxidant defense
and glucose homeostasis in experimental diabetes. Sodium selenate (SS) or selenomethionine (SM) were administered (2 μmol
Se kg−1 day−1) via orogastric route to streptozotocine (STZ)-induced diabetic rats in addition to basal diet for 12 weeks. Glucose levels
in whole blood, glutathione peroxidase (GSH-Px) activity in erythrocytes, Se and fructosamine levels in plasma were evaluated
monthly. Plasma Se levels increased significantly in all diabetic groups compared to basal measurements, being more prominent
in SM group [p(SM3/SM0) = 0.018]. The increase in GSH-Px activities was significant at the end of the second month in SS [p(SS2/SS0) = 0.028], whereas at the end of the third month in SM the value was lower [p(SM3/SM0) = 0.018] and the unsupplemented diabetic control (DC) groups, p(DC3/DC0) = 0.012. Glucose increased significantly only in DC group. Fructosamine increased gradually in all diabetic groups, being
significant in DC and SS groups. At the end of the third month, highest fructosamine levels were observed in SS group, which
were significantly higher than the SM group [p(SM/SS) = 0.010]. In conclusion, Se augmented the antioxidant defense by increasing
GSH-Px activity and this effect was more prominent when Se was supplemented as SM, which exerted positive effects also on
glucose homeostasis. 相似文献
202.
Murat Ayaz Nizamettin Dalkilic Hulagu Bariskaner Seckin Tuncer Ilhami Demirel 《Biological trace element research》2007,116(3):301-309
Gender differences are related to the manner in which the heart responds to chronic and acute stress conditions of physiological
and pathological nature. Depending on dose, sodium selenite acts as an antioxidant proven to have beneficial effects in several
pathological conditions G. Drasch, J. Schopfer, and G. N. Schrauzer, Selenium/cadmium ratios in human prostates: indicators
of prostate cancer risk of smokers and non-smokers, and relevance to the cancer protective effects of selenium,Biol. Trace Element Res.
103(2), 103–107 (2005); R. G. Kasseroller and G. N. Schrauzer, Treatment of secondary lymphedema of the arm with physical decongestive
therapy and sodium selenite: a review,Am. J. Ther.
7(4), 273–279 (2000); G. N. Schrauzer, Anticarcinogenic effects of selenium,Cell. Mol. Life Sci.
57(13–14), 1864–1873 (2000); I. S. Palmer and O. E. Olson, Relative toxicities of selenite and selenate in the drinking water of rats,J. Nutr.
104(3), 306–314 (1974). To date, little is known about the gender-dependent direct effects of toxic doses of selenite on electrophysiology
of the cardiovascular system H. A. Schroeder and M. Mitchener, Selenium and tellurium in rats: effect on growth, survival
and tumors,J. Nutr.
101(11), 1531–1540 (1971); G. N. Schrauzer, The nutritional significance, metabolism and toxicology of selenomethionine,Adv. Food Nutr. Res.
47, 73–112 (2003). In the present study, the effects of in vitro toxic concentrations of sodium selenite ranging from 10-6 M to 10-3 M were tested on both male and female rat heart preparations. The toxic effects seen in an electrocardiogram and left ventricular
pressure were dose and sex dependent at most of the tested concentrations. The present study clearly shows that at toxic doses,
stress conditions are induced by selenite, resulting in gender-dependent modifications of the heart function. This modification
is more pronounced in the contraction cascade of female rats. Males, on the other hand, had been much more affected in excitation-related
parameters. 相似文献
203.
Legall H Stiel H Beck M Leupold D Gruszecki WI Lokstein H 《Journal of biochemical and biophysical methods》2007,70(3):369-376
Peridinin-chlorophyll a protein (PCP) is a unique water soluble antenna complex that employs the carotenoid peridinin as the main light-harvesting pigment. In the present study the near edge X-ray absorption fine structure (NEXAFS) spectrum of PCP was recorded at the carbon K-edge. Additionally, the NEXAFS spectra of the constituent pigments, chlorophyll a and peridinin, were measured. The energies of the lowest unoccupied molecular levels of these pigments appearing in the carbon NEXAFS spectrum were resolved. Individual contributions of the pigments and the protein to the measured NEXAFS spectrum of PCP were determined using a “building block” approach combining NEXAFS spectra of the pigments and the amino acids constituting the PCP apoprotein. The results suggest that absorption changes of the pigments in the carbon near K-edge region can be resolved following excitation using a suitable visible pump laser pulse. Consequently, it may be possible to study excitation energy transfer processes involving “optically dark” states of carotenoids in pigment-protein complexes by soft X-ray probe optical pump double resonance spectroscopy (XODR). 相似文献
204.
Serum or plasma can be utilized in a variety of studies targeted toward the discovery of disease biomarkers. In this study, the proteome profiles of plasma samples prepared using various anticoagulants (EDTA, heparin or citrate), were compared with those of serum using two-dimensional electrophoresis (2-DE). Proteins which evidenced different levels in the plasma and serum were screened and identified using ESI-Q-TOF MS/MS. The proteins which became detectable after the removal of fibrinogen from serum were identified as pigment epithelial differentiating factor (four spots), fetuin-like protein, and the hemopexin precursor. In particular, three proteins, pre-serum amyloid P component, plasma glutathione peroxidase precursor, and tetranectin, evidenced increased volume intensity only in the plasma samples prepared with EDTA. 相似文献
205.
Susan E. Crow Christopher W. Swanston Kate Lajtha J. Renée Brooks Heath Keirstead 《Biogeochemistry》2007,85(1):69-90
Soil organic matter (SOM) is often separated by physical means to simplify a complex matrix into discrete fractions. A frequent
approach to isolating two or more fractions is based on differing particle densities and uses a high density liquid such as
sodium polytungstate (SPT). Soil density fractions are often interpreted as organic matter pools with different carbon (C)
turnover times, ranging from years to decades or centuries, and with different functional roles for C and nutrient dynamics.
In this paper, we discuss the development and mechanistic basis of common density-based methods for dividing soil into distinct
organic matter fractions. Further, we directly address the potential effects of dispersing soil in a high density salt solution
on the recovered fractions and implications for data interpretation. Soil collected from forested sites at H. J. Andrews Experimental
Forest, Oregon and Bousson Experimental Forest, Pennsylvania was separated into light and heavy fractions by floatation in
a 1.6 g cm−3 solution of SPT. Mass balance calculations revealed that between 17% and 26% of the original bulk soil C and N content was
mobilized and subsequently discarded during density fractionation for both soils. In some cases, the light isotope was preferentially
mobilized during density fractionation. During a year-long incubation, mathematically recombined density fractions respired
∼40% less than the bulk soil at both sites and light fraction (LF) did not always decompose more than the heavy fraction (HF).
Residual amounts of tungsten (W) present even in well-rinsed fractions were enough to reduce microbial respiration by 27%
compared to the control in a 90-day incubation of Oa material. However, residual W was nearly eliminated by repeated leaching over the year-long incubation, and is not likely
the primary cause of the difference in respiration between summed fractions and bulk soil. Light fraction at Bousson, a deciduous
site developed on Alfisols, had a radiocarbon-based mean residence time (MRT) of 2.7 or 89 years, depending on the interpretation
of the radiocarbon model, while HF was 317 years. In contrast, both density fractions from H. J. Andrews, a coniferous site
developed on andic soils, had approximately the same MRT (117 years and 93 years for LF and HF). At H. J. Andrews the organic
matter lost during density separation had a short MRT (19 years) and can account for the difference in respired CO2 between the summed fractions and the bulk soil. Recognition and consideration of the effects of the density separation procedure
on the recovered fractions will help prevent misinterpretation and deepen our understanding of the specific role of the recovered
organic matter fractions in the ecological context of the soil studied. 相似文献
206.
Shin DJ Kim E Park SB Jang WC Bae Y Han J Jang Y Joung B Lee MH Kim SS Huang H Chahine M Yoon SK 《Life sciences》2007,80(8):716-724
Brugada syndrome (BS) is an inherited cardiac disorder associated with a high risk of sudden cardiac death and is caused by mutations in the SCN5A gene encoding the cardiac sodium channel alpha-subunit (Na(v)1.5). The aim of this study was to identify the genetic cause of familial BS and characterize the electrophysiological properties of a novel SCN5A mutation (W1191X). Four families and one patient with BS were screened for SCN5A mutations by PCR and direct sequencing. Wild-type (WT) and mutant Na(v)1.5 channels were expressed in tsA201 cells, and the sodium currents (I(Na)) were analyzed using the whole-cell patch-clamp technique. A novel mutation, W1191X, was identified in a family with BS. Expression of the WT or the mutant channel (Na(v)1.5/W1191X) co-transfected with the beta(1)-subunit in tsA201 cells resulted in a loss of function of Na(v)1.5 channels. While voltage-clamp recordings of the WT channel showed a distinct acceleration of Na(v)1.5 activation and fast inactivation kinetics, the Na(v)1.5/W1191X mutant failed to generate any currents. Co-expression of the WT channel and the mutant channel resulted in a 50% reduction in I(Na). No effect on activation and inactivation were observed with this heterozygous expression. The W1191X mutation is associated with BS and resulted in the loss of function of the cardiac sodium channel. 相似文献
207.
Prodocimo V Galvez F Freire CA Wood CM 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(5):519-528
Na+ and Ca2+ regulation were compared in two euryhaline species, killifish (normally estuarine-resident) and rainbow trout (normally freshwater-resident)
during an incremental salinity increase. Whole-body unidirectional fluxes of Na+ and Ca2+, whole body Na+ and Ca2+, and plasma concentrations (trout only), were measured over 1-h periods throughout a total 6-h protocol of increasing salinity
meant to simulate a natural tidal flow. Killifish exhibited significant increases in both Na+ influx and efflux rates, with efflux slightly lagging behind efflux up to 60% SW, but net Na+ balance was restored by the time killifish reached 100% SW. Whole body Na+ did not change, in agreement with the capacity of this species to tolerate daily salinity fluctuations in its natural habitat.
In contrast, rainbow trout experienced a dramatic increase in Na+ influx (50-fold relative to FW values), but not Na+ efflux between 40 and 60% SW, resulting in a large net loading of Na+ at higher salinities (60–100% SW), and increases in plasma Na+ and whole body Na+ at 100% SW. Killifish were in negative Ca2+ balance at all salinities, whereas trout were in positive Ca2+ balance throughout. Ca2+ influx rate increased two- to threefold in killifish at 80 and 100% SW, but there were no concomitant changes in Ca2+ efflux. Ca2+ flux rates were affected to a larger degree in trout, with twofold increases in Ca2+ influx at 40% SW and sevenfold increases at 100% SW. Again, there was no change in Ca2+ efflux with salinity, so plasma Ca2+ concentration increased in 100% SW. As the killifish is regularly submitted to increased salinity in its natural environment,
it is able to rapidly activate changes in unidirectional fluxes in order to ensure ionic homeostasis, in contrast to the trout. 相似文献
208.
von Engelhardt W Dycker Ch Lechner-Doll M 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2007,177(6):631-640
In camelids the ventral parts of compartments 1 and 2 (C1/C2) and the total surface of compartment 3 of the forestomach are
lined with tubular glands, whereas in ruminants the surface of the forestomach is composed entirely of stratified, squamous
epithelium. Thus, differences in absorption rates between these foregut fermenters can be expected. In five camels C1/C2 was
temporarily isolated, washed and filled with buffer solutions. Absorption of short-chain fatty acids (SCFA) and net absorption
of sodium and water were estimated relative to Cr-ethylenediaminetetraacetic acid as a fluid marker. SCFA were extensively
absorbed in the forestomach; clearance rates of SCFA with different chain lengths were equal. After lowering the pH of solutions
SCFA absorption rates increased, but much less than the increase of the non-ionized fraction. Absorption of propionate was
lower when acetate had been added. Findings suggest that most of the SCFA in camels are transported in the ionized form, most
likely via an anion exchange mechanism. Net water absorption is closely related to net sodium absorption. Apparently water
absorption results from an iso-osmotic process. Differences between absorption mechanisms of SCFA from the forestomach of
camelids and ruminants are discussed. 相似文献
209.
Na+ accumulation in shoot is related to water transport in K+-starved sunflower plants but not in plants with a normal K+ status 总被引:1,自引:0,他引:1
Sunflower plants (Helianthus annuus L. cv Sun-Gro 380) grown in nutrient solutions with different K+ levels were used to study the effect of potassium status on water uptake, Na+ uptake and Na+ accumulation in the shoot. Changes in nutrient potassium levels induced evident differences in internal potassium content. When both low and normal-K+ plants were exposed to 22 °C and salinity conditions (25 or 50 mM NaCl) during a short time period (9 h), water uptake in low-K+ plants was greater than in normal-K+ plants. In addition, K+ starvation favoured the Na+ uptake and the Na+ accumulation both in the root and in the shoot. When the plants were exposed to heat stress by a sharp increase of the temperature to 32 °C during the same period of time, the stimulating effect of K+ starvation on the water uptake was even greater. The high temperature increased Na+ uptake in both types of plants, but the Na+ accumulation in the shoot was only favoured in low-K+ plants. The results suggest that Na+ accumulation in the shoot is more dependent on the water uptake in low-K+ plants than in normal-K+ plants, and this effect could explain the greatest susceptibility to the salinity in K+-starved plants under high transpiration conditions, which are typical in dry climates. 相似文献
210.
The strength and pattern of coevolution between amino acid residues vary depending on their structural and functional environment.
This context dependence, along with differences in analytical technique, is responsible for the different results among coevolutionary
analyses of different proteins. It is thus important to perform detailed study of individual proteins to gain better insight
into how context dependence can affect coevolutionary patterns even within individual proteins, and to unravel the details
of context dependence with respect to structure and function. Here we extend our previous study by presenting further analysis
of residue coevolution in cytochrome c oxidase subunit I sequences from 231 vertebrates using a statistically robust phylogeny-based maximum likelihood ratio method.
As in previous studies, a strong overall coevolutionary signal was detected, and coevolution within structural regions was
significantly related to the Cα distances between residues. While the strong selection for adjacent residues among predicted coevolving pairs in the surface
region indicates that the statistical method is highly selective for biologically relevant interactions, the coevolutionary
signal was strongest in the transmembrane region, although the distances between coevolving residues were greater. This indicates
that coevolution may act to maintain more global structural and functional constraints in the transmembrane region. In the
transmembrane region, sites that coevolved according to polarity and hydrophobicity rather than volume had a greater tendency
to colocalize with just one of the predicted proton channels (channel H). Thus, the details of coevolution in cytochrome c oxidase subunit I depend greatly on domain structure and residue physicochemical characteristics, but proximity to function
appears to play a critical role. We hypothesize that coevolution is indicative of a more important functional role for this
channel.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献