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91.
The antifungal spirocyclic guanidine alkaloid, ptilomycalin A, from marine sponge Monanchora arbuscula, inhibits melanogenesis of Cryptococcus neoformans in vitro through inhibition of biosynthesis of laccase in the melanin biosynthetic pathway with an IC(50) of 7.3 μM. 相似文献
92.
Tadeusz M. Krygowski Wojciech P. Oziminski Christopher A. Ramsden 《Journal of molecular modeling》2011,17(6):1427-1433
The reasons behind changes of aromaticity in 10 unsubstituted aza-azoles were analysed by employing the natural bond orbital
(NBO) approach at the MP2/6-311+G(d,p) level of theory. Sum of occupations of p
z
orbitals at atoms in the ring correlates well with the magnetism based aromaticity index NICS as well as with the number
of nitrogen atoms in the ring. Changes of NICS depend strongly in a linear way on the number of NN bonds. Classification of
azoles based on the number of pyridine-type nitrogen atoms vicinal to NH is supported by plotting the relative occupation
of π orbitals (πocc) against the relative occupation of σ orbitals (σocc) for all individual atoms in rings. 相似文献
93.
Noncovalent DIDS binding to Band 3 (AE1) protein in human erythrocyte membranes, modified by non-penetrating, water soluble
1-ethyl-3-(4-azonia-4,4-dimethylpentyl)-carbodiimide iodide (EAC), was studied at 0°C in the presence of 165 mM KCl. Under
experimental conditions applied up to (48 ± 5) % of irreversible chloride self-exchange inhibition was observed. The apparent
dissociation constant, KD, for “DIDS-Band 3” complex, determined from the chloride transport experiments, was (34 ± 3) nM
and (80 ± 12) nM for control and EAC-treated resealed ghosts, respectively. The inhibition constant, Ki, for DIDS was (35
± 6) nM and (60 ± 8) nM in control and EAC-treated ghosts, respectively. The reduced affinity for DIDS reversible binding
was not a result of negative cooperativity of DIDS binding sites of Band 3 oligomer since Hill’s coefficients were indistinguishable
from 1 (within the limit error) both for control and EAC-treated ghosts. By using tritium-labeled DIDS, 4,4’-diisothiocyanato-2,2’-stilbenedisulfonate
([3H]DIDS), the association rate constant, k+1 (M−1s−1), was measured. The mean values of (4.3 ± 0.7) × 105 M−1s−1 for control and (2.7 ± 0.7) × 105 M−1s−1 for EAC-treated ghosts were obtained. The mean values for KD, evaluated from [3H]DIDS binding measurements, were (37 ± 9) nM and (90 ± 21) nM for control and EAC-modified ghosts, respectively. The results
demonstrate that EAC modification of AE1 reduces about 2-fold the affinity of AE1 for DIDS. It is suggested that half of the
subunits are modified near the transport site by EAC. 相似文献
94.
Ogrodzka K Niedźwiedzki T Chwała W 《Acta of bioengineering and biomechanics / Wroc?aw University of Technology》2011,13(3):47-54
The aim of the study was to assess the variability of parameters characterising the gait of persons suffering from degenerative changes of the knee joint and their influence on the ankle and hip joints. The values of the angular changes in the knee, ankle and hip joints in the three planes of motion were assessed. Locomotion tests were performed on 27 persons, aged between 60 and 74, using Vicon 250, the three-dimensional analysis system. The sharpest deviations from the results of the control group were revealed in the transverse and frontal planes. Degenerative knee joint disease has changed the gait stereotype causing a reduction in the economy of gonarthrosis patients' locomotion, the influence of the disease on the function of the neighbouring joints is also distinctly marked. 相似文献
95.
Halina Szatyłowicz Tadeusz Marek Krygowski Aneta Jezierska-Mazzarello 《Journal of molecular modeling》2011,17(1):125-131
Due to gradual and controlled changes of interatomic distances between heavy atoms in OH…F− of C6H5OH…F− systems it was possible to study the electronic structure evolution. Computation at B3LYP/6-311+G(d,p) level of theory was
performed for this purpose. Changes in charges at atoms and characteristics at bond critical points (BCPs) of the H-bond region
and also in distant parts of the systems were investigated by means of natural bond orbitals (NBO) and atoms in molecules
(AIM) analyses. It is shown that at the border line between partially covalent and non-covalent H-bonding (Espinosa et al.
in J Chem Phys 117:5529, 2002; Grabowski et al. in J Phys Chem B 110:6444, 2006) with the H…F interatomic distance ∼1.8 Ǻ the hydrogen atom has the most positive charge. In addition, the change in the
atomic charge values in the interacting region affects the phenyl ring properties. The decrease of the sum of atomic charges
as well as of the aromaticity was noticed when the OH….F distance is shortened. 相似文献
96.
Abstract: Casein kinase II (CKII) is a protein kinase acting in the intracellular cascade of reactions activated by growth factor receptors, and that has a profound influence on cell proliferation and survival. In this investigation, we studied the changes in the activity and levels of CKII in the rat brain exposed to 10. 15 and 20 min of transient forebrain ischemia followed by variable periods of reperfusion. The cytosolic CKII activity decreased during reperfusion by ∼ 30 and ∼ 50% in the selectively vulnerable areas, striatum and the CA1 region of the hippocampus, respectively. In the resistant CA3 region of hippocampus and neocortex, the activity increased by ∼ 20 and ∼ 60%, respectively. The postischemic changes in CKII activity were dependent on the duration of the ischemic insult. The levels of CKII did not change after ischemia, suggesting that the enzyme is modulated by covalent modification or is interacting with an endogenous inhibitor/activator. Treatment of the cytosolic fraction from cortex of rats exposed to ischemia and 1 h of reperfusion with agarose-bound phosphatase decreased the activity of CKII to control levels, suggesting that CKII activation after ischemia involves a phosphorylation of the enzyme. The correlation between postischemic CKII activity and neuronal survival implies that preservation or activation of CKII activity may be important for neuronal survival after cerebral ischemia. 相似文献
97.
98.
99.
Kim JK Sala-Mercado JA Rodriguez J Scislo TJ O'Leary DS 《American journal of physiology. Heart and circulatory physiology》2005,288(3):H1374-H1380
Previous studies showed that the arterial baroreflex opposes the pressor response mediated by muscle metaboreflex activation during mild dynamic exercise. However, no studies have investigated the mechanisms contributing to metaboreflex-mediated pressor responses during dynamic exercise after arterial baroreceptor denervation. Therefore, we investigated the contribution of cardiac output (CO) and peripheral vasoconstriction in mediating the pressor response to graded reductions in hindlimb perfusion in conscious, chronically instrumented dogs before and after sinoaortic denervation (SAD) during mild and moderate exercise. In control experiments, the metaboreflex pressor responses were mediated via increases in CO. After SAD, the metaboreflex pressor responses were significantly greater and significantly smaller increases in CO occurred. During control experiments, nonischemic vascular conductance (NIVC) did not change with muscle metaboreflex activation, whereas after SAD NIVC significantly decreased with metaboreflex activation; thus SAD shifted the mechanisms of the muscle metaboreflex from mainly increases in CO to combined cardiac and peripheral vasoconstrictor responses. We conclude that the major mechanism by which the arterial baroreflex buffers the muscle metaboreflex is inhibition of metaboreflex-mediated peripheral vasoconstriction. 相似文献
100.
Growth parameters and photosynthetic pigments in leaf segments of Zea mays exposed to cadmium, as related to protection mechanisms 总被引:1,自引:0,他引:1
The influence of cadmium on growth parameters and photosynthetic pigment content was studied in maize leaf segments differing in tissue maturity. Experiments were carried out with maize seedlings Zea mays L. cv. Hidosil treated with 25, 50, 100, 150 and 200 microM Cd for 14 days under low light conditions. Tissue age-dependent decrease of fresh mass, dry mass and area of the leaf segments was correlated with Cd concentration in the growth medium. Cd induced changes in chlorophyll and carotenoid contents, and the specific areas and densities of the leaf segments were dependent on age and metal concentration. Results are discussed with respect to the protection mechanisms in the leaf segments. 相似文献