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1.
Both myoblasts and myotubes in cultures of clonal rat muscle cells have action potential Na+ ionophore activity. The ionophore is activated by batrachotoxin (K0.5 = 3 to 5 × 10?7 M) and veratridine (K0.5 = 4 to 6 × 10?5 M) which compete for the same activation site. As in denervated rat muscle, the ionophore of cultured muscle is 100 fold more resistant to inhibition by tetrodotoxin (K0.5 = 1.5 to 3 × 10?6 M) and 20 fold more resistant to inhibition by saxitoxin (K0.5 = 1.5 to 3 × 10?7 M) than in nerve, innervated muscle, or cultured neuroblastoma cells.  相似文献   

2.
Increase in body weight and adiposity has deleterious consequences on health. The aim of this study was to compare morphological and metabolic changes in the arterial vessels of Wistar rats with conditions of obesity, hypoestrogenism, and hypoestrogenism plus obesity. Ovariectomized rats (hypoestrogenic condition) received 30 % sugar in drinking water plus standard diet during 10 weeks. The hypoestrogenic-obese (HE-OB) group presented increase in weight, blood pressure, hypertriglyceridemia, and hyperglycemia compared with other groups. The morphological study in aortic vessels from HE showed damage in endothelial smooth muscle tissue compared with the other groups. Adipose cells volume in HE-OB (59.33?±?2.38 μ3?×?105) and obese (OB) (54.95?±?1.36 μ3?×?105) groups were significantly larger than control group (36.38?±?0.98 μ3?×?105). In the HE group adipocyte hyperplasia was observed, while in OB group adipocyte hypertrophy and hyperplasia was shown. The vascular reactivity in HE-OB and OB groups presented decrease in the relaxation to acetylcholine compared with control conditions (p?<?0.05), whereas the addition of NG-nitro-l-arginine methyl ester resulted in a greater inhibition of relaxation in HE-OB and OB groups compared with control conditions (p?<?0.05). These findings suggest that the dysfunction in blood vessels observed in estrogen deficiency and obesity conditions contributes to early cardiovascular alterations.  相似文献   

3.
The migratory history of tapertail anchovy Coilia nasus in the Yangtze River Estuary, China was investigated using otolith Sr:Ca ratios and two-dimensional images of the Sr level from an X-ray electron probe microanalyzer (EPMA). The results showed that 17 of the 22 young-of-the-year (YOY) specimens had low Sr:Ca ratios (1.2–2.4?×?10?3;1.5?±?0.3?×?10?3) at the central otolith area, indicating their riverine origin and initial freshwater residence. In addition, 11 of the 14 adult specimens had low Sr:Ca ratios (1.3–2.2?×?10?3; 1.7?±?0.4?×?10?3) at the central otolith area but showed alternating changes between high (>4.0?×?10?3) and low (<2.5?×?10?3) values outside of this region, reflecting their riverine origin and the migration between freshwater and estuarine habitats. These 28 specimens represented the anadromous population in this region. The other 5 YOY specimens had high Sr:Ca ratios (3.6–5.9?×?10?3; 4.8?±?0.8?×?10?3) throughout the life history. Similarly, the other 3 adult specimens had high Sr:Ca ratios (4.0–5.7?×?10?3; 4.8?±?0.7?×?10?3) at the central otolith area but showed alternating changes between low and high values outside this region, suggesting that estuarine-origin non-anadromous individuals occurred in this region. The average of the otolith Sr:Ca ratios and Sr level mapping along the life-history transects could be used as a scalar for charting the migratory history of the tapertail anchovy in the Yangtze River Estuary: <2.0?×?10?3 for freshwater residence and 3.5–6.0?×?10?3 for estuarine residence.  相似文献   

4.
Prostacyclin (PGI2) produced a biphasic response in canine isolated basilar arteries. In low doses (1 × 10?8M?1 × 10?7M) PGI2 caused a slight but consistent relaxation of resting muscle tone. In low concentrations (1 × 10?8M?1 × 10?6M) PGI2 antagonized muscle contractions caused by serotonin or prostaglandin (PG) F. This relaxant effect with low doses of PGI2 on the isolated cerebral artery contrasts with findings obtained with other PGs and supports the hypothesis that PGI2 is a mediator of vasodilatation. However, in 1 × 10?5M concentrations PGI2 contracted the arterial muscle and did not antagonize contractions induced by serotonin or PGF.  相似文献   

5.
A new type of toxicity biphasically dependent on concentration was observed with diethyldithiocarbamate, a metal chelator utilized in medicine. As judged by cell survival and [3H]Urd incorporation, diethyldithiocarbamate was maximally toxic to T lymphocytes and polymorphonuclears at 2.5×10?5 M (first phase) and at higher than 2.5×10?3 M (second phase), but was not toxic at intermediate concentrations around 2.5×10?4 M. The response of chelator treated T lymphocytes to phytohemagglutinin was also biphasic. The first toxic phase was partially reversed by 2.5×10?5 M ZnCl2, while the second phase was partially reversed by 10?2 M CuCl2. This suggests that inhibition of Zn-metalloenzymes in the first phase and of Cu-metalloenzymes in the second may play a crucial role in the mechanism of toxicity. The second toxic phase may be in part due to the observed inhibition of superoxide dismutase rendering the cells susceptible to oxygen toxicity, like obligate anaerobes.  相似文献   

6.
Fluorescence study of the complexation between uranyl salophen (L) and some common anions in acetonitrile–water (90:10, v/v) solution showed a tendency of L toward acetate ion (AcO?). The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and acetate ion which was utilized as the basis for the selective detection of AcO?. The association constant of the 1:1 complex formation of L–AcO? was calculated as 6.60 × 106. The linear response range of the fluorescent chemosensor covers a AcO? concentration range of 1.6 × 10?7 to 2.5 × 10?5 mol/L, with a detection limit of 2.5 × 10?8 mol/L. L showed a selective and sensitive fluorescence enhancement response toward acetate ion over I3?, NO3?, CN?, CO32?, Br?, Cl?, F?, H2PO4? and SO42?, which was attributed to the higher stability of inorganic complex between acetate and L. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

7.
The short term uptake of phosphate involving 10 min absorption followed by 5 min desorption, both at 30 °C, in the concentration range 1.0×10?9 to 7.5×10?2 M KH2PO4 by fresh and washed maize (Zea mays L. cv. Ganga Safed-2) roots can be described by a single isotherm having five phases (0 and I–IV) with regularly spaced kinetic constants. Almost identical kinetics were observed in both fresh and washed maize roots. The kinetics of phase 0 in the concentration range 1.0×10?9–3.0×10?5 M. was sigmoidal in fresh maize roots, however, in washed tissue exhibited 2 phases termed here as 0a and 0b. 0a covered the concentration range 1.0×10?9–5.0×10?6 M and 0b 6.0×10?6–3.0×10?5 M. In the concentration range 1.0×10?4–7.5×10?2 M four distinct phases, termed as I, II, III and IV were evident in both fresh and washed maize roots. Each phase obeyed Michaelis—Menten kinetics. The values of Km and Vmax have been estimated for each phase. The uptake isotherm was accompanied by discontinuous transitions.  相似文献   

8.
We evaluated the potential of a granular formulation of Metarhizium brunneum F52 containing microsclerotia (MbMSc granules) for control of Aedes aegypti by targeting eggs. MbMSc granules produced infective conidia within 14 days after application to 2.5?g moist potting soil, producing 5.9?×?105, 2.08?×?106 and 6.85?×?106 conidia from 1, 5 and 25?mg MbMSc granules, respectively. Application of MbMSc triggered premature eclosion of eggs (EC50?=?12?mg) with percentages as high as 31?±?2.9% and 67?±?4.3% of the eggs treated with 5 and 25?mg MbMSc granules, respectively, after 14 days on moist filter paper. Premature eclosion of eggs started at 3 days subsequent to MbMSc granule application and survival of larvae was significantly reduced for granule treated eggs (74?±?2.2%, 39?±?2.0% and 23?±?4.9% larvae survived for 1, 5 and 25?mg granule treatments, respectively, EC50?=?4.9?mg). When MbMSc granules were applied in moist potting soil with mosquito eggs, rates of 1, 5 and 25?mg of MbMSc granules significantly reduced adult emergence with only 81?±?2.1%, 47?±?1.9%, and 34?±?2.1% emergence, respectively (EC50?=?7?mg). Eggs treated with increasing concentrations of fungal conidia enhanced premature eclosion of eggs with an EC50?=?1.6?×?106 conidia/mL. Our results demonstrate that MbMSc granules are a promising candidate for control of A. aegypti and that fermentative production of Mb F52 microsclerotia as the active propagule has the potential for use for mosquito control.  相似文献   

9.
C Y Chiou 《Life sciences》1974,14(9):1721-1733
(2-Hydroxyethyl) methyldiethylammonium (DEC; Diethylcholine) was found to inhibit cholinergic fibers slowly, both in skeletal muscle (ED50: 2.25 × 10?5 M in chick biventer cervicis and 42 mg/kg in rat sciatic-gastrocnemius) and in smooth muscle preparations (ED50: 7.7 × 10?4 M in transmurally stimulated guinea-pig ileum) without having any effect on dose-response curves of acetylcholine to contract chick biventer cervicis, frog rectus abdominis and guinea-pig ileum. These results indicate that DEC acts at the prejunctional nerve fibers, but not at the postjunctional cholinergic receptor sites. DEC was acetylated efficiently both by choline acetyltransferase and by minced rat brain, suggesting that it can be acetylated to acetyl-DEC in the nerve ending. Acetyl-DEC was found to block acetylcholine actions competitively both in smooth and in skeletal muscle preparations (1 × 10?3 ? 1 × 10?2M) indicating that the acetylated product of DEC can serve as an antagonist at the cholinergic receptor site. It is therefore concluded that DEC is a false cholinergic transmitter.  相似文献   

10.
The objective of this study was to identify loci associated with tail biting or being a victim of tail biting in Norwegian crossbred pigs using a genome-wide association study with PLINK case?Ccontrol analysis. DNA was extracted from hair or blood samples collected from 98 trios of crossbred pigs located across Norway. Each trio came from the same pen and consisted of one pig observed to initiate tail biting, one pig which was the victim of tail biting and a control pig which was not involved in either behaviour. DNA was genotyped using the Illumina PorcineSNP60 BeadChip whole-genome single-nucleotide polymorphism (SNP) assay. After quality assurance filtering, 53,952 SNPs remained comprising 74 animals (37 pairs) for the tail biter versus control comparison and 53,419 SNPs remained comprising 80 animals (40 pairs) for the victim of tail biting versus control comparison. An association with being a tail biter was observed on Sus scrofa chromosome 16 (SSC16; p?=?1.6?×?10?5) and an unassigned chromosome (p?=?3.9?×?10?5). An association with being the victim of tail biting was observed on Sus scrofa chromosomes 1 (SSC1; p?=?4.7?×?10?5), 9 (SSC9; p?=?3.9?×?10?5), 18 (SSC18; p?=?7?×?10?5 for 9,602,511?bp, p?=?3.4?×?10?5 for 9,653,881?bp and p?=?5.3?×?10?5 for 29,577,783 bp) and an unassigned chromosome (p?=?6.1?×?10?5). An r 2?=?0.96 and a D???=?1 between the two SNPs at 9?Mb on SSC18 indicated extremely high linkage disequilibrium, suggesting that these two markers represent a single locus. These results provide evidence of a moderate genetic association between the propensity to participate in tail-biting behaviour and the likelihood of becoming a victim of this behaviour.  相似文献   

11.
The growth response (increase in weight) of cultured explants from seedling date (Phoenix dactylifera L.) and mature coconut (Cocos nucifera L. cv. Malayan Dwarf) palms to source and concentration of organic nitrogen. carbohydrate, auxins, cytokinins and gibberellins was examined. Growth was strongly stimulated by the presence of auxins (10?7 to 10?6M), cytokinins (10?6 to 10?5M), high concentrations of sucrose (0.2 M), and in the absence of NH4Cl, by organic sources of reduced nitrogen. Higher concentrations of auxin (2,4-D or NAA at 10?6 to 10?5M) which still stimulated growth of Phoenix tissue, proved inhibitory to growth of freshly excised Cocos tissues. Explants from both palms initiated roots when subcultured on a medium with increased levels of auxin (NAA, 2.5 × 10?6 to 2.5 × 10?5M) and reduced levels of cytokinin (6-BAP, 5 × 10?8M). Isolated roots excised from these explants continued growth and produced new laterals when subcultured on media with GA3 (5 × 10?7M) and reduced levels of auxin, cytokinin, and either minerals or sucrose.  相似文献   

12.
In this study, effective gamete concentrations, egg viability, and fertilization volumes were evaluated for Haliotis midae (L.). Sperm concentrations between 5?×?103 and 5?×?104?mL?1 (p?>?0.05) consistently resulted in high hatch-out rates (96?±?1%). At concentrations higher than 5?×?105?mL?1, hatch-out rates decreased to 69?±?7% (p??1 resulted in high fertilization rates, with 50?eggs?mL?1 being the ideal concentration for fertilization in H. midae. Egg viability was consistently high up to 100?min post-spawning, with a decrease in hatch-out success, when eggs were fertilized 120?min post-spawning. Fertilization volumes did not affect successful hatch-out. The results from this study can be implemented by South African abalone farms to increase hatch-out rates and subsequent culture. It can also be used as basis for the development of fertilization protocols in other marine invertebrate species.  相似文献   

13.

Purpose

Life cycle assessment (LCA) has largely focused on characterizing the impact of outdoor emissions. However, the intake fraction (iF) of indoor air emissions could be more important. The present paper aims to determine the long-term intake fractions of indoor emissions, including multiple indoor removal pathways such as sorption on indoor surfaces, and to compare it to the outdoor intake fraction.

Method

The developed model accounts for the different removal pathways in buildings, including air exchange, degradation in the gas phase, degradation on surfaces, and finally partitioning between air, walls, and furniture assuming a kinetically limited material transfer between gas phase and a near-surface film. The indoor intake fraction is presented as a function of the adsorption and degradation rate on surfaces.

Results and discussion

The intake fraction of volatile substances is only affected by the ventilation rate, with a constant intake fraction of 1?×?10?2. For ozone-sensitive substances, indoor gas phase reactions can significantly reduce the intake fraction. Semi-volatile substances are affected by the adsorption and degradation on room surfaces. For highly adsorbing substances, the decrease in intake fraction is limited to a minimum value of 2.5?×?10?4 by the mass transfer rate between air and room surfaces for a typical office or residence room in developed countries with temperate climate. Indoor intake fraction is compared to outdoor intake fraction calculated using the Impact 2002 multimedia model. Typical calculated indoor intake fraction values are in a significantly higher range (2.5?×?10?4 to 1?×?10?2) than inhalation outdoor values (1?×?10?9 to 1?×?10?6).

Conclusions

This paper opens new possibilities to assess the health impact of indoor and outdoor air emissions in a consistent way, including surface sorption??a major removal pathway for semi-volatile compounds. By combining the newly calculated intake fractions with effect factors and with indoor and outdoor emissions per functional unit, it becomes possible to consistently account for indoor exposure in methods such as LCA  相似文献   

14.
Bone is one of the main target organs for the lanthanides (Ln). Biodistribution studies of Tm-based compounds in vivo showed that bone had significant uptake. But the effect of Tm3+ on primary mouse bone marrow stromal cells (BMSCs) has not been reported. So we investigated the effect and underlying mechanisms of Tm3+ on BMSCs. Cell viability, cell apoptosis, reactive oxygen species (ROS) level, lactate dehydrogenase (LDH) activity and mitochondrial membrane potential (MMP) were studied. The results indicated that Tm3+ increased the viability of BMSCs at concentrations of 1?×?10?7, 1?×?10?6, 1?×?10?5, and 1?×?10?4 mol/L in a dose-dependent manner, turned to decrease the viability of BMSCs at the highest concentration of 1?×?10?3 mol/L for 24, 48, and 72 h. Tm3+ at 1?×?10?3 mol/L promoted apoptosis of BMSCs, increased the ROS and LDH levels, and decreased MMP in BMSCs. Taken together, we demonstrated that Tm3+ at 1?×?10?3 mol/L might induce cellular apoptosis through mitochondrial pathway. These results may be helpful for more rational application of Tm-based compounds in the future.  相似文献   

15.
Kinetin has a stimulating effect in the Avena straight-growth test. The action of different concentrations of kinetin, 2.5 × 10?7, 2.5 × 10?6 and 2.5 × 10?5M, in combination with different concentrations of IAA was studied in this test. It was shown that the effect of low IAA concentrations, 0.25 × 10?7 and 1 × 10?7M, was strongly enhanced by the addition of all the kinetin concentrations investigated. The effect of the highest IAA concentrations, 25 × 10?7 and 100 × 10?7M, on the other hand, was inhibited relatively strongly by the highest employed concentration of kinetin. The results are explained as due to a kinetin-produced increase of auxin in the coleoptile segment, which in combination with low IAA concentrations can lead to a growth stimulation and with high IAA concentrations to a growth inhibition. Since kinetin in purification and chromatography of auxin can partly follow IAA, thereby affecting the quantitative yield, it is emphasized that, prior to the test, auxin extracts containing cytokinins should be freed from the latter by, for example, gel filtration or paper electrophoresis.  相似文献   

16.
Glutamate-NAD oxidoreductase, E.C. 1.4.1.3 (GDH), from seedlings of Beta vulgaris cv. Rota, Jahnsch Peragis Comp., was enzymatically characterized. This enzyme with molecular weight of 2.6 × 105 has a pH optimum of around 8 for animation of α-KGA and around 9.5 for the desamination of glutamate. The apparent Km for α-KGA is 6.7 × 10?4M, for NH3 2.5 × 10?3M, for NADH 3.2 × 10?5M and for NAADPH 5.5 × 10?4M. NAD1 inhibits the reaction non-competitively when NADPH serves as substrate. The apparent K1 is 4.5 × 10?4M. The data are discussed on relation to the properties of GDH from other plant sources.  相似文献   

17.
Abstract

In this study, human exposure and risks of metals through fish ingestion were predicted. Concentrations of 10 metals (Cd, As, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn) in 17 commonly eaten fish species in Saudi Arabia were characterized. Using the fish ingestion patterns, chronic daily intakes of metals among the Saudi and expatriate populations were predicted to be in the ranges of 8.89?×?10?06–1.08?×?10?02 and 6.59?×?10?06–7.97?×?10?03?mg/kg/day, respectively. The average cancer risks from inorganic arsenic were 2.76?×?10?05 and 2.09?×?10?05 for Saudi and expatriate, and the ranges were 1.61?×?10?09–1.58?×?10?03 and 2.64?×?10?09–1.27?×?10?03, respectively. The predicted risks were much lower than the previously reported risks. There were 47.4% and 42.4% chances that cancer risks would be higher than 1.0?×?10?05 (10 per million) among Saudi and expatriate, respectively. The average cumulative hazard index (HI) for Saudi and expatriate were 0.324 and 0.239 with the ranges of 0.0142–7.26 and 0.017–6.43, respectively. Approximately 3.06% and 1.56% cases among Saudi and expatriate had HI greater than unity, indicating possible health concern, respectively. Through comprehensive understanding of exposure and risks, strategies can be adopted to protect human health.  相似文献   

18.
Bisphenol A (BPA) [2,2-bis-(4-hydroxyphenyl) propane] is an important industrial agent, made by combining acetone and phenol, that is used extensively as a monomer in the production of polycarbonate plastics and as a precursor of epoxy resins. Micronucleus assays have served as an index of cytogenetic damage in in vivo and in vitro studies. We studied the genotoxic and cytotoxic effects of BPA on bovine peripheral lymphocytes in vitro. Lymphocyte cultures from two donors were exposed to four different concentrations of BPA (1?×?10?4, 1?×?10?5, 1?×?10?6, and 1?×?10?7 mol.L?1) for 48 h. The highest concentration of BPA (1?×?10?4 mol.L?1) resulted in a significant increase in the number of micronuclei in comparison with the negative control (67.50?±?2.121/1,000 binucleated cells versus 36.0?±?5.657/1,000 binucleated cells in the DMSO control, P??=??0.018). BPA did not affect the nuclear division index at any treatment concentrations. The present results thus demonstrate a significant genotoxic effect by BPA on bovine peripheral lymphocytes in vitro, only at the highest concentration.  相似文献   

19.
Biofuels derived from non-crop sources, such as microalgae, offer their own advantages and limitations. Despite high growth rates and lipid accumulation, microalgae cultivation still requires more energy than it produces. Furthermore, invading organisms can lower efficiency of algae production. Simple environmental changes might be able to increase algae productivity while minimizing undesired organisms like competitive algae or predatory algae grazers. Microalgae are susceptible to pH changes. In many production systems, pH is kept below 8 by CO2 addition. Here, we uncouple the effects of pH and CO2 input, by using chemical pH buffers and investigate how pH influences Nannochloropsis salina growth and lipid accumulation as well as invading organisms. We used a wide range of pH levels (5, 6, 7, 8, 9, and 10). N. salina showed highest growth rates at pH 8 and 9 (0.19?±?0.008 and 0.19?±?0.011, respectively; mean ± SD). Maximum cell densities in these treatments were reached around 21 days into the experiment (95.6?×?106?±?9?×?106 cells mL?1 for pH 8 and 92.8?×?106?±?24?×?106 cells mL?1 for pH 9). Lipid accumulation of unbuffered controls were 21.8?±?5.8 % fatty acid methyl esters content by mass, and we were unable to trigger additional significant lipid accumulation by manipulating pH levels at the beginning of stationary phase. Ciliates (grazing predators) occurred in significant higher densities at pH 6 (56.9?±?39.6?×?104 organisms mL?1) than higher pH treatments (0.1–6.8?×?104 organisms mL?1). Furthermore, the addition of buffers themselves seemed to negatively impact diatoms (algal competitors). They were more abundant in an unbuffered control (12.7?±?5.1?×?104 organisms mL?1) than any of the pH treatments (3.6–4.7?×?104 organisms mL?1). In general, pH values of 8 to 9 might be most conducive to increasing algae production and minimizing invading organisms. CO2 addition seems more valuable to algae as an inorganic carbon source and not as an essential mechanism to reduce pH.  相似文献   

20.
Alkaline hydrolysis and subcritical water degradation were investigated as ex-situ remediation processes to treat explosive-contaminated soils from military training sites in South Korea. The addition of NaOH solution to the contaminated soils resulted in rapid degradation of the explosives. The degradation of explosives via alkaline hydrolysis was greatly enhanced at pH ≥12. Estimated pseudo-first-order rate constants for the alkaline hydrolysis of 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in contaminated soil at pH 13 were (9.6?±?0.1)×10?2, (2.2?±?0.1)×10?1, and (1.7?±?0.2)×10?2 min?1, respectively. In the case of subcritical water degradation, the three explosives were completely removed at 200–300°C due to oxidation at high temperatures and pressures. The degradation rate increased as temperature increased. The pseudo-first-order rate constants for DNT, TNT, and RDX at 300°C were (9.4?±?0.8)×10?2, (22.8?±?0.3)×10?2, and (16.4?±?1.0)×10?2, respectively. When the soil-to-water ratio was more than 1:5, the extent of alkaline hydrolysis and subcritical water degradation was significantly inhibited.  相似文献   

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