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991.
992.
Chromaffin granules are involved in catecholamine synthesis and traffic in the adrenal glands. The transporting membrane proteins
of chromaffin granules play an important role in the ion homeostasis of these organelles. In this study, we characterized
components of the electrogenic 86Rb+ flux observed in isolated chromaffin granules. In order to study single channel activity, chromaffin granules from the bovine
adrenal medulla were incorporated into planar lipid bilayers. Four types of cationic channel were found, each with a different
conductance. The unitary conductances of the potassium channels are 360 ± 10 pS, 220 ± 8 pS, 152 ± 8 pS and 13 ± 3 pS in a
gradient of 450/150 mM KCl, pH 7.0. A multiconductance potassium channel with a conductivity of 110 ± 8 pS and 31 ± 4 pS was
also found. With the exception of the 13 pS conductance channel, all are activated by depolarizing voltages. One type of chloride
channel was also found. It has a unitary conductance of about 250 pS in a gradient of 500/150 mM KCl, pH 7.0. 相似文献
993.
Ciesielska E Szulawska A Studzian K Ochocki J Malinowska K Kik K Szmigiero L 《Journal of inorganic biochemistry》2006,100(10):1579-1585
In search for new platinum-based anticancer drugs, four cisplatin analogues, which contain pyrazole rings as non-leaving ligands, have been synthesized: cis-PtCl(2)(3,5-DM HMPz)(2), cis-PtCl(2)(Pz)(2), cis-PtCl(2)(ClMPz)(2), and cis-PtCl(2)(HMPz)(2), where Pz=pyrazole, H=hydroxyl, M=methyl. We tested their cytotoxicity, apoptosis induction ability, DNA damaging and modification properties comparing them in respect to the parent compound. The cytotoxic activity of these platinum pyrazole complexes toward the murine leukemia cell line was 2.9-3.8 times lower than actvity of cisplatin. The tested compounds varied in their mechanism of action by producing different DNA lesions. The most interesting compound seems to be the complex with chloromethyl groups at N1 of pyrazole rings, which exhibited the highest ability to form bifunctional adducts with DNA in vitro. 相似文献
994.
Tubek S 《Biological trace element research》2006,114(1-3):1-5
A negative relationship between water hardness and cardiovascular mortality rate was demonstrated and became a source of interest
regarding minerals and trace metals in the pathogenesis of atherosclerosis, cardiovascular diseases, and arterial hypertension.
Higher incidences of sudden death, cerebrovascular diseases, arterial hypertension, and coronary heart disease have been reported
in soft water areas. A major research effort has been devoted to the problem in an attempt to find a protective factor in
hard water or a detrimental factor or element in soft water. The roles of calcium, magnesium, cobalt, lithium, vanadium, silicon,
manganese, and copper have been considered potentially beneficial, whereas those of cadmium, lead, silver, zinc, and antimony
have been considered potentially harmful. Cobalt and zinc have been attributed both roles. In the present article, the role
of trace quantities of several elements in mineral water in the etiopathogenesis of primary arterial hypertension is reviewed.
An erratum to this article is available at . 相似文献
995.
Kołodziej Barbara Kochan Ewa Kazimierczak Jerzy Chmiel Aleksander 《Plant Growth Regulation》2006,48(1):13-19
American ginseng (Panax quinquefolium L.) is a perennial medicinal herb originally grown in Canada and USA, and recently also in China, Australia, Holland and
Poland. Several commercial preparations are produced from ginseng roots, that are known for their antifatigue, antitumor,
antistress and immune system stimulating functions. The medicinal properties are due mainly to the active components – ginsenosides.
In this work, the results of field cultivation experiments are presented that examine the effects of foliar application of
several growth regulators on quality parameters and ginsenoside content of P. quinuefolium roots. The growth regulators tested, i.e., kinetin, daminozide, mixture of gibberellic acid (GA3) with potassium salt of α-naphthalene acetic acid (kNAA) and new preparation – IPO-1 – benzimidazole derivative (obtained
from the Institute of Organic Industry in Warsaw – at present during the process of patent), were applied at a concentration
of 100 or 200 mg l−1 in the middle of June in the 2nd year of vegetation. After 4 years of cultivation, the roots were dug up and dried, and subsequently
the quantitative analysis of individual saponins (Rb1, Rb2, Rc, Rd, Re, Rg1) by HPLC was performed. Growth regulators significantly affected quality parameters, morphological features and accumulation
of individual and total ginsenosides in ginseng roots. Regardless of doses, the plant roots treated with growth regulators
had a higher content of total ginsenosides in comparison to the control. The growth regulators also affected individual ginsenosides
level and narrowed the ratio of Rb:Rg group. The application of kinetin, daminozide and benzimidazole derivative for foliar spray during 2nd year of American ginseng
vegetation caused a significant increase in air dry weight of roots and aboveground parts whereas the mixture of GA3 and kNAA showed a decreasing effect. An increase of roots size was observed using higher doses (200 mg l−1) of kinetin and daminozide while a decreasing tendency appeared with the application of the other preparations. 相似文献
996.
Nickel-induced Inhibition of Wheat Root Growth is Related to H2O2 Production, but not to Lipid Peroxidation 总被引:1,自引:1,他引:0
Effects of exogenous nickel (Ni: 10 and 200 μM) on growth, mitotic activity, Ni accumulation, H2O2 content and lipid peroxidation as well as the activities of various antioxidative enzymes, such as superoxide dismutase (SOD),
catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GSH-Px) were investigated in wheat roots. A considerable
Ni accumulation in the roots occurred at both the concentrations. Although Ni at 10 μM did not have any significant effect
on root growth, it strongly inhibited the root growth at 200 μM. Mitotic activity in the root tips was not significantly affected
by exposure of the seedlings to 10 μM Ni; however, it was almost completely inhibited at 200 μM treatment. Ni stress did not
result in any significant changes in CAT and APX activities as well as lipid peroxidation. However, H2O2 concentration increased up to 82% over the control in the roots of seedlings exposed to 200 μM Ni. There was a significant
decline in both SOD (50%) and GSH-Px (20–30%) activities in the roots when the seedlings were treated with 200 μM Ni. The
results indicated that a strong inhibition of wheat root growth caused by Ni stress was not due to enhanced lipid peroxidation,
but might be related to the accumulation of H2O2 in root tissue. 相似文献
997.
998.
999.
1000.
Time-resolved fluorescence of 3-methylbenzimidazole (m3B) was used to study stacking interaction between base moieties in di-, tri- and tetra-phosphate analogues of 3-methylbenzimidazolyl(5′-5′)guanosine (m3Bp
n
G, n = 2, 3, 4), using 5′-triphosphate of 3-methylbenzimidazole riboside (m3BTP) as reference. Fluorescence intensity decays of all compounds cannot be satisfactory fitted with single-exponential function. Although an increase of a number of exponents led to better fits, interpretation of the individual exponential terms, i.e. pre-exponential amplitudes and fluorescence lifetimes, cannot be adequately characterized. We show that these fluorescence decays are best fitted by power-like function derived from physically justified distribution of the fluorescence lifetimes, and characterized by the mean value of the excited-state lifetime and relative variance of lifetime fluctuations around the mean value. The latter led to the parameter of heterogeneity and number of decay paths, which depend on the factors responsible for non-radiative decay of the excited state, including base–base stacking interaction. This was studied by means of changes of temperature and the number of phosphate groups in dinucleotides. It was shown that the strongest effect of stacking interactions, characterized by lowest values of both fluorescence mean decay time and relative variance, occurs in the case of m3Bp3G containing the same number of phosphates as natural mRNA cap. The possible importance of these results for interpretation of the mechanism of function of the mRNA cap structure is discussed. 相似文献