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61.
Micuda S Hodac M Sispera L Parízek P Pleskot M Zimova G Cerman J Martínková J Pidrman V 《Physiological research / Academia Scientiarum Bohemoslovaca》2001,50(2):191-196
The present study was undertaken to evaluate the use of cortisol 6beta-hydroxylation in defining the effect of amiodarone on cytochrome CYP3A activity. To accomplish this goal, the in vivo activity of CYP3A was estimated by measuring the 24-hour urinary excretion of 6beta-hydroxycortisol (6beta-OHC) and by calculating 24-hour ratio of 6beta-hydroxycortisol to urinary free cortisol (6beta-OHC/UFC ratio). Nine cardiac patients scheduled for amiodarone treatment were recruited to participate in this study. Urine was collected over a 24-hour period from each subject before the first amiodarone administration and during the third day of oral administration of amiodarone (200 mg four times daily as a loading dose). Three days of amiodarone treatment caused a significant decrease (p<0.05) in both the 6beta-OHC/UFC ratio and the 24-hour urinary excretion of 6beta3-OHC. These results suggest that amiodarone is an inhibitor of CYP3A activity. 相似文献
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64.
Klára Řeháková Eliška Zapomělová Ondřej Prášil Jana Veselá Hana Medová Aharon Oren 《Hydrobiologia》2009,636(1):77-88
There are several conflicting hypothesis that deal with the influence of flooding in the natural river–floodplain systems.
According to the Flood Pulse Concept, the flood pulses are not considered to be a disturbance, while some recent studies have
proven that floods can be a disturbance factor of phytoplankton development. In order to test whether flooding acts as a disturbance
factor in the shallow Danubian floodplain lake (Lake Sakadaš), phytoplankton dynamics was investigated during two different
hydrological years—extremely dry (2003) without flooding and usually flooded (2004). A total of 18 phytoplankton functional
groups were established. The sequence of phytoplankton seasonality can be summarized P/D → E (W1, W2) → C/P (only in potamophase) → S2/H1/SN/S1 → W1/W2 → P/D. The canonical correspondence analysis (CCA) demonstrated that the water level was a significant environmental
variable in 2004. Due to the higher total biomass of Bacillariophyceae established under potamophase conditions, floodings
in the early spring seem to be a stimulating factor for phytoplankton development. On the other hand, the flood pulses in
May and June had dilution effects on nutrients, so that a significantly lower phytoplankton biomass was established indicating
that flooding pulses can be regarded as a disturbance event. Such conditions supported diatom development (D, P, C species)
and prolonged its dominance in the total phytoplankton biomass. A long-lasting Cyanoprokaryota bloom (various filamentous
species—S1, S2, SN and H1 representatives) with very high biomass characterized the limnophase (dry conditions) in summer and autumn of both
years. In-lake variables (lake morphology, internal loadings of nutrients from sediments, light conditions) seem to be important
for the appearance of Cyanoprokaryota bloom. The equilibrium phase was found during the Cyanoprokaryota bloom only in the
extremely dry year. This study showed that depending on the time scale occurrence, flood pulses can be a stimulating or a
disturbance factor for phytoplankton development in Lake Sakadaš.
Handling editor: J. Padisak 相似文献
65.
Phosphorus nutrition and mycorrhiza effects on grass leaf growth. P status- and size-mediated effects on growth zone kinematics 总被引:2,自引:0,他引:2
This study tested whether leaf elongation rate (LER, mm h(-1)) and its components--average relative elemental growth rate (REGRavg, mm mm(-1) h(-1)) and leaf growth zone length (L(LGZ), mm)--are related to phosphorus (P) concentration in the growth zone (P(LGZ) mg P g(-1) tissue water) of Lolium perenne L. cv. Condesa and whether such relationships are modified by the arbuscular mycorrhizal fungus (AMF) Glomus hoi. Mycorrhizal and non-mycorrhizal plants were grown at a range of P supply rates and analysed at either the same plant age or the same tiller size (defined by the length of the sheath of the youngest fully expanded leaf). Both improved P supply (up to 95%) and AMF (up to 21%) strongly increased LER. In tillers of even-aged plants, this was due to increased REGRavg and L(LGZ). In even-sized tillers, it was exclusively due to increased REGRavg. REGRavg was strictly related to P(LGZ) (r2 = 0.95) and independent of tiller size. Conversely, L(LGZ) strictly depended on tiller size (r2 = 0.88) and not on P(LGZ). Hence, P status affected leaf growth directly only through effects on relative tissue expansion rates. Symbiosis with AMF did not modify these relationships. Thus, no evidence for P status-independent effects of AMF on LER was found. 相似文献
66.
A novel Arabidopsis thaliana mutant of one member of the pentatricopeptide repeat (PPR) gene family has been identified among T-DNA insertion lines. Tagging
of the At1g53330 gene caused the appearance of a semi-lethal mutation with a complex phenotypic expression from embryo lethality
associated with the abnormal pattern of cell division during globular to heart transition to fertile plants with just subtle
phenotypic changes. The PPR protein At1g53330.1 was predicted to be targeted to mitochondria by TargetP and MitoProt programs.
Complementation analysis confirmed that the phenotype is a result of a single T-DNA integration. A thorough functional analysis
of this mutant aimed at finding a particular organelle target of At1g53330.1 protein will follow. 相似文献
67.
68.
Ristvejová J Kopecký V Sovová Z Balsera M Arellano JB Green M Ettrich R 《Biochemical and biophysical research communications》2006,345(1):287-291
Infrared and Raman spectroscopy were applied to identify restraints for the structure determination of the 20 amino acid loop between two beta-sheets of the N-terminal region of the PsbQ protein of the oxygen evolving complex of photosystem II from Spinacia oleracea by restraint-based homology modeling. One of the initial models has shown a stable fold of the loop in a 20 ns molecular dynamics simulation that is in accordance with spectroscopic data. Cleavage of the first 12 amino acids leads to a permanent drift in the root means square deviation of the protein backbone and induces major structural changes. 相似文献
69.
Houstek J Pícková A Vojtísková A Mrácek T Pecina P Jesina P 《Biochimica et biophysica acta》2006,1757(9-10):1400-1405
ATP synthase is a key enzyme of mitochondrial energy conversion. In mammals, it produces most of cellular ATP. Alteration of ATP synthase biogenesis may cause two types of isolated defects: qualitative when the enzyme is structurally modified and does not function properly, and quantitative when it is present in insufficient amounts. In both cases the cellular energy provision is impaired, and diminished use of mitochondrial DeltamuH+ promotes ROS production by the mitochondrial respiratory chain. The primary genetic defects have so far been localized in mtDNA ATP6 gene and nuclear ATP12 gene, however, involvement of other nuclear genes is highly probable. 相似文献
70.
Bird schistosomes and cases of human cercarial dermatitis occur worldwide, but the number of cases is not monitored. Experiments with two schistosomes, namely Trichobilharzia szidati and T. regenti, show that they possess potent tools to penetration bird and mammalian skin, as well as exhibit species-specific migration patterns within vertebrate bodies. Therefore, the infections may affect different organs/tissues e.g. lungs or spinal cord. In this minireview, the adaptations and pathogenic effects of bird schistosomes in experimental mammals are discussed, and some ideas/hypotheses on risks to humans from exposure to bird schistosome cercariae are expressed. 相似文献