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891.
Susanne Olsson 《Inorganica chimica acta》2011,377(1):181-184
Two crystalline complexes of bis(η1-methylcyclopentadienyl)zinc, [Zn(C5H4Me)2(py)2] (1), where py is pyridine, and [Zn(C5H4Me)2(teeda)], 2, where teeda is N,N,N′,N′-tetraethylethylenediamine have been isolated. The crystal structures of 1 and 2 are the first crystal structures for Zn(C5H4Me)2 complexes reported in the literature; both structures display η1-coordination of the methylcyclopentadienyl ring to zinc, and both compounds display chirogenic α-carbon atoms. While 1 forms racemic crystals, 2 undergoes spontaneous resolution and crystals of 2 are thus enantiomerically pure. 1H NMR showed that Zn(C5H4Me)2 is stereochemically labile in solution with only one signal for the Cp-protons. This fact opens up the possibility for total spontaneous resolution and absolute asymmetric synthesis. 相似文献
892.
Natural killer (NK) cells are important effectors in resistance to viral infections. The role of NK cells in the acute response to human immunodeficiency virus 1 (HIV-1) infected cells was investigated in a mouse model based on a HIV-1/murine leukemia virus (MuLV) pseudovirus. Splenocytes infected with HIV-1/MuLV were injected intraperitoneally and local immunologic responses and persistence of infected cells were investigated. In vivo depletion with an anti-NK1.1 antibody showed that NK cells are important in resistance to virus infected cells. Moreover, NK cell frequency in the peritoneal cavity increased in response to infected cells and these NK cells had a more mature phenotype, as determined by CD27 and Mac-1 expression. Interestingly, after injection of HIV-1/MuLV infected cells, but not MuLV infected cells, peritoneal NK cells had an increased cytotoxic activity. In conclusion, NK cells play a role in the early control of HIV-1/MuLV infected cells in vivo. 相似文献
893.
Fuchs R Schraml E Leitinger G Letofsky-Papst I Stelzer I Haas HS Schauenstein K Sadjak A 《Experimental cell research》2011,317(20):2969-2980
Even though the erythroleukemia cell lines K562 and HEL do not express α1-adrenoceptors, some α1-adrenergic drugs influence both survival and differentiation of these cell lines. Since Ca2+ is closely related to cellular homeostasis, we examined the capacity of α1-adrenergic drugs to modulate the intracellular Ca2+ content in K562 cells. Because of morphological alterations of mitochondria following α1-adrenergic agonist treatment, we also scrutinized mitochondrial functions. In order to visualize the non-adrenoceptor binding site(s) of α1-adrenergic drugs in erythroleukemia cells, we evaluated the application of the fluorescent α1-adrenergic antagonist BODIPY® FL-Prazosin. We discovered that the α1-adrenergic agonists naphazoline, oxymetazoline and also the α1-adrenergic antagonist benoxathian are able to raise the intracellular Ca2+-content in K562 cells. Furthermore, we demonstrate that naphazoline treatment induces ROS-formation as well as an increase in Δψm in K562 cells. Using BODIPY® FL-Prazosin we were able to visualize the non-adrenoceptor binding site(s) of α1-adrenergic drugs in erythroleukemia cells. Interestingly, the SERCA-inhibitor thapsigargin appears to interfere with the binding of BODIPY® FL-Prazosin.Our data suggest that the effects of α1-adrenergic drugs on erythroleukemia cells are mediated by a thapsigargin sensitive binding site, which controls the fate of erythroleukemia cells towards differentiation, senescence and cell death through modulation of intracellular Ca2+. 相似文献
894.
Sebens S Bauer I Geismann C Grage-Griebenow E Ehlers S Kruse ML Arlt A Schäfer H 《The Journal of biological chemistry》2011,286(47):40911-40921
Adaptation of epithelial cells to persistent oxidative stress plays an important role in inflammation-associated carcinogenesis. This adaptation process involves activation of Nrf2 (nuclear factor-E2-related factor-2), which has been recently shown to contribute to carcinogenesis through the induction of proteasomal gene expression and proteasome activity. To verify this possible link between inflammation, oxidative stress, and Nrf2-dependent proteasome activation, we explored the impact of inflammatory (M1) macrophages on the human colon epithelial cell line NCM460. Transwell cocultures with macrophages differentiated from granulocyte monocyte-colony-stimulating factor-treated monocytes led to an increased activity of Nrf2 in NCM460 cells along with an elevated proteasome activity. This higher proteasome activity resulted from Nrf2-dependent induction of proteasomal gene expression, as shown for the 19 and 20 S subunit proteins S5a and α5, respectively. These effects of macrophage coculture were preceded by an increase of reactive oxygen species in cocultured NCM460 cells and could be blocked by catalase or by the reactive oxygen species scavenger Tiron, whereas transient treatment of NCM460 cells with H(2)O(2) similarly led to Nrf2-dependent proteasome activation. Through the Nrf2-dependent increase of proteasomal gene expression and proteasome activity, the sensitivity of NCM460 cells to tumor necrosis factor-related apoptosis-inducing ligand- or irinotecan-induced apoptosis declined. These findings indicate that inflammatory conditions such as the presence of M1 macrophages and the resulting oxidative stress are involved in the Nrf2-dependent gain of proteasome activity in epithelial cells, e.g. colonocytes, giving rise of greater resistance to apoptosis. This mechanism might contribute to inflammation-associated carcinogenesis, e.g. of the colon. 相似文献
895.
Kohls S Stamp P Knaak C Messmer R 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,123(2):327-338
Partial restoration of male fertility limits the use of C-type cytoplasmic male sterility (C-CMS) for the production of hybrid
seeds in maize. Nevertheless, the genetic basis of the trait is still unknown. Therefore, the aim to this study was to identify
genomic regions that govern partial restoration by means of a QTL analysis carried out in an F2 population (n = 180). This population was derived from the Corn Belt inbred lines B37C and K55. F2BC1 progenies were phenotyped at three locations in Switzerland. Male fertility was rated according to the quality and number
of anthers as well as the anthesis-silking interval. A weak effect of environment on the expression of partial restoration
was reflected by high heritabilities of all fertility-related traits. Partial restoration was inherited like an oligogenic
trait. Three major QTL regions were found consistently across environments in the chromosomal bins 2.09, 3.06 and 7.03. Therefore,
a marker-assisted counter-selection of partial restoration is promising. Minor QTL regions were found on chromosomes 3, 4,
5, 6 and 8. A combination of partial restorer alleles at different QTL can lead to full restoration of fertility. The maternal
parent was clearly involved in the partial restoration, because the restorer alleles at QTL in bins 2.09, 6.04 and 7.03 originated
from B37. The three major QTL regions collocated with other restorer genes of maize, a phenomenon, which seems to be typical
for restorer genes. Therefore, a study of the clusters of restorer genes in maize could lead to a better understanding of
their evolution and function. In this respect, the long arm of chromosome 2 is particularly interesting, because it harbors
restorer genes for the three major CMS systems (C, T and S) of maize. 相似文献
896.
In C3 leaves, the mesophyll conductance to CO2 diffusion, gm, determines the drawdown in CO2 concentration from intercellular airspace to the chloroplast stroma. Both gm and stomatal conductance limit photosynthetic rate and vary in response to the environment. We investigated the response of gm to changes in CO2 in two Arabidopsis genotypes (including a mutant with open stomata, ost1), tobacco and wheat. We combined measurements of gas exchange with carbon isotope discrimination using tunable diode laser absorption spectroscopy with a CO2 calibration system specially designed for a range of CO2 and O2 concentrations. CO2 was initially increased from 200 to 1000 ppm and then decreased stepwise to 200 ppm and increased stepwise back to 1000 ppm, or the sequence was reversed. In 2% O2 a step increase from 200 to 1000 ppm significantly decreased gm by 26–40% in all three species, whereas following a step decrease from 1000 to 200 ppm, the 26–38% increase in gm was not statistically significant. The response of gm to CO2 was less in 21% O2. Comparing wild type against the ost1 revealed that mesophyll and stomatal conductance varied independently in response to CO2. We discuss the effects of isotope fractionation factors on estimating gm. 相似文献
897.
King J Unterkofler K Teschl G Teschl S Koc H Hinterhuber H Amann A 《Journal of mathematical biology》2011,63(5):959-999
Recommended standardized procedures for determining exhaled lower respiratory nitric oxide and nasal nitric oxide (NO) have
been developed by task forces of the European Respiratory Society and the American Thoracic Society. These recommendations
have paved the way for the measurement of nitric oxide to become a diagnostic tool for specific clinical applications. It
would be desirable to develop similar guidelines for the sampling of other trace gases in exhaled breath, especially volatile
organic compounds (VOCs) which may reflect ongoing metabolism. The concentrations of water-soluble, blood-borne substances
in exhaled breath are influenced by: (i) breathing patterns affecting gas exchange in the conducting airways, (ii) the concentrations
in the tracheo-bronchial lining fluid, (iii) the alveolar and systemic concentrations of the compound. The classical Farhi
equation takes only the alveolar concentrations into account. Real-time measurements of acetone in end-tidal breath under
an ergometer challenge show characteristics which cannot be explained within the Farhi setting. Here we develop a compartment
model that reliably captures these profiles and is capable of relating breath to the systemic concentrations of acetone. By
comparison with experimental data it is inferred that the major part of variability in breath acetone concentrations (e.g.,
in response to moderate exercise or altered breathing patterns) can be attributed to airway gas exchange, with minimal changes
of the underlying blood and tissue concentrations. Moreover, the model illuminates the discrepancies between observed and
theoretically predicted blood-breath ratios of acetone during resting conditions, i.e., in steady state. Particularly, the
current formulation includes the classical Farhi and the Scheid series inhomogeneity model as special limiting cases and thus
is expected to have general relevance for a wider range of blood-borne inert gases. The chief intention of the present modeling
study is to provide mechanistic relationships for further investigating the exhalation kinetics of acetone and other water-soluble
species. This quantitative approach is a first step towards new guidelines for breath gas analyses of volatile organic compounds,
similar to those for nitric oxide. 相似文献
898.
Patil J Stucki S Nussberger J Schaffner T Gygax S Bohlender J Imboden H 《Regulatory peptides》2011,167(1):31-41
Although the physiological and pharmacological evidences suggest a role for angiotensin II (Ang II) with the mammalian heart, the source and precise location of Ang II are unknown. To visualize and quantitate Ang II in atria, ventricular walls and interventricular septum of the rat and human heart and to explore the feasibility of local Ang II production and function, we investigated by different methods the expression of proteins involved in the generation and function of Ang II. We found mRNA of angiotensinogen (Ang-N), of angiotensin converting enzyme, of the angiotensin type receptors AT(1A) and AT? (AT(1B) not detected) as well as of cathepsin D in any part of the hearts. No renin mRNA was traceable. Ang-N mRNA was visualized by in situ hybridization in atrial ganglial neurons. Ang II and dopamine-β-hydroxylase (DβH) were either colocalized inside the same neuronal cell or the neurons were specialized for Ang II or DβH. Within these neurons, the vesicular acetylcholine transporter (VAChT) was neither colocalized with Ang II nor DβH, but VAChT-staining was found with synapses en passant encircle these neuronal cells. The fibers containing Ang II exhibited with blood vessels and with cardiomyocytes supposedly angiotensinergic synapses en passant. In rat heart, right atrial median Ang II concentration appeared higher than septal and ventricular Ang II. The distinct colocalization of neuronal Ang II with DβH in the heart may indicate that Ang II participates together with norepinephrine in the regulation of cardiac functions: produced as a cardiac neurotransmitter Ang II may have inotropic, chronotropic or dromotropic effects in atria and ventricles and contributes to blood pressure regulation. 相似文献
899.
Herter S Schmidt M Thompson ML Mikolasch A Schauer F 《Applied microbiology and biotechnology》2011,90(3):1037-1049
Laccases are copper-containing phenol oxidases that are commonly found in many types of plant, insect, fungi and bacteria.
Whilst phenol oxidases have been well characterized in fungal species, laccase-type enzymes originating from bacteria have
been much less well defined. Bacteria belonging to the family Azotobacteraceae share many morphological characteristics with
strains already known to exhibit polyphenol and phenol oxidase activity; and hence the aim of this work was to identify and
characterize a novel laccase from the isolated strain Azotobacter chroococcum SBUG 1484 in an attempt to provide further understanding of the roles such enzymes play in physiological development. Laccase
activity was clearly observed through oxidation of 2,6-dimethoxyphenol, other typical substrates including: methoxy-monophenols,
ortho- and para-diphenols, 4-hydroxyindole, and the non-phenolic compound para-phenylenediamine. A. chroococcum SBUG 1484 showed production of a cell-associated phenol oxidase when grown under nitrogen-fixing conditions, and was also
observed when cells enter the melanogenic and encystment stages of growth. Catechol which is structurally related to melanin
compounds was also released from Azotobacter cells into the surrounding culture medium during nitrogen-fixing growth. From our results we propose that a membrane-bound
laccase plays an important role in the formation of melanin, which was monitored to correlate with progression of A. chroococcum SBUG 1484 cells into the encystment stage of growth. 相似文献
900.
Schöpper H Palme R Ruf T Huber S 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(8):1089-1100
Stress, when extreme or chronic, can have a negative impact on health and survival of mammals. This is especially true for
females during reproduction when self-maintenance and investment in offspring simultaneously challenge energy turnover. Therefore,
we investigated the effects of repeated stress during early- and mid-gestation on the maternal stress axis, body weight gain
and reproductive output. Female guinea pigs (Cavia aperea f. porcellus, n = 14) were either stressed (treatment: exposure to strobe light in an unfamiliar environment on gestational day -7, 0, 7,
14, 21, 28, 35, 42) or left completely undisturbed (control) throughout pregnancy. Females of both groups received the same
respective diets, and reproductive parameters were evaluated upon parturition. Additionally, hormonal data were obtained from
blood and feces. The stress exposure induced a significant increase in plasma cortisol concentrations during the afternoon.
In contrast to this short-term response in plasma cortisol concentrations, we found no significant differences in the levels
of cortisol metabolites in feces collected after stress exposure between groups and even significantly decreased levels of
fecal cortisol metabolites on non-stress days over time in treatment females. Among treatment females, gain in body weight
was attenuated over gestation and body weight was lower compared to control females during lactation, especially in cases
of large litter sizes. No differences could be seen in the reproductive parameters. We conclude that repeated stress exposure
with strobe light during early- and mid-gestation results in a down-regulation of the hypothalamic–pituitary–adrenal axis
and lower weight gain in treatment females, but has no effect on reproductive output. 相似文献