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101.
102.
Katarzyna Kurpiewska Josep Font Marc Ribó Maria Vilanova Krzysztof Lewiński 《Proteins》2009,77(3):658-669
To investigate the structural origin of decreased pressure and temperature stability, the crystal structure of bovine pancreatic ribonuclease A variants V47A, V54A, V57A, I81A, I106A, and V108A was solved at 1.4–2.0 Å resolution and compared with the structure of wild‐type protein. The introduced mutations had only minor influence on the global structure of ribonuclease A. The structural changes had individual character that depends on the localization of mutated residue, however, they seemed to expand from mutation site to the rest of the structure. Several different parameters have been evaluated to find correlation with decrease of free energy of unfolding ΔΔGT, and the most significant correlation was found for main cavity volume change. Analysis of the difference distance matrices revealed that the ribonuclease A molecule is organized into five relatively rigid subdomains with individual response to mutation. This behavior consistent with results of unfolding experiments is an intrinsic feature of ribonuclease A that might be surviving remnants of folding intermediates and reflects the dynamic nature of the molecule. Proteins 2009. © 2009 Wiley‐Liss, Inc. 相似文献
103.
Driven by seasonality, many common recurrent infectious diseases are characterized by strong annual, biennial and sometimes
irregular oscillations in the absence of vaccination programs. Using the seasonally forced SIR epidemic model, we are able
to provide new insights into the dynamics of recurrent diseases and, in some cases, specific predictions about individual
outbreaks. The analysis reveals a new threshold effect that gives clear conditions for the triggering of future disease outbreaks
or their absence. The threshold depends critically on the susceptibility S
0 of the population after an outbreak. We show that in the presence of seasonality, forecasts based on the susceptibility S
0 are more reliable than those based on the classical reproductive number R
0 from the conventional theory.
相似文献
104.
105.
Janusz Szklarzewicz Dariusz Matoga Krzysztof Lewiński 《Inorganica chimica acta》2007,360(6):2002-2008
Ligand-field photolysis of K4[Mo(CN)8] · 2H2O in 98% N2H4 · H2O yields the catalytical decomposition of N2H4 into NH3 and N2. From irradiated solutions of octacyanomolybdate(IV) both in NH3(aq) and 98% N2H4 · H2O(l) as solvents, the salt of the formula (PPh4)2[Mo(CN)4O(NH3)] · 2H2O was isolated. The salt is not formed by direct ligand replacement in tetracyanooxomolybdate(IV) ions derived from K3Na[Mo(CN)4O2] · 6H2O as the solute in similar conditions. The X-ray crystal structure and spectral properties of (PPh4)2[Mo(CN)4O(NH3)] · 2H2O are described. The improved method of the synthesis of K4[Mo(CN)8] · 2H2O is also presented. 相似文献
106.
Papillary thyroid carcinoma (PTC) represents an example of tumour with high incidence of oncogenic sequences, such as RET/PTC and Trk. Both of them arise from the fusion of 3' terminal sequences of TK domain of RET or NTRK1 gene, respectively, with 5' terminal sequences of their activating genes. In case of NTRK1 oncogene, several rearrangement types are observed, characteristic for PTC: Trk (TMP3), Trk-T1, Trk-T2, Trk-T3 and Trk-2h, observed in human breast cancer cell line. Studies from different geographical regions, revealed significant population differences in the incidence of Trk rearrangements (0-50%), while within the same population, the frequency of Trk in spontaneous and radiation-associated PTCs is similar. The results of studies, focused on the correlation between tumour genotype and the histopathological type of tumour, involving cases of both RET/PTC and Trk rearrangements in PTC, are not unequivocal. In many studies, no correlation was observed between the presence of RET and/or NTRK1 rearrangement and such parameters, as patient's age at diagnosis, gender, histopathological type of tumour or clinical stage (TNM stage grouping), although the earliest clinical symptoms and the worst disease outcomes were observed for RET/NTRK1 rearrangement positive tumours. Differences in the rearrangement incidence between male and female patients were associated with the latency period of radiation-associated tumours, being significantly lower in women. In general, it is assumed that oncogenic Trk sequences are typical for the spontaneous type of PTC. 相似文献
107.
Bolanowski M Bar-Andziak E Kos-Kudła B Krzyzanowska-Swiniarska B Lewiński A Lomna-Bogdanov E Milewicz A Sowiński J Zgliczyński W 《Endokrynologia Polska》2007,58(4):350-3; discussion 354-5
Consensus statement of the Polish Society of Endocrinology, regarding presurgical somatostatin analogs in acromegaly has been presented. It is suggested to administer depot somatostatin analog (Octreotide LAR at the dose 20 mg and then 30 mg or equivalent doses of Lanreotide Autogel 90/120 mg every 4 weeks) in order to normalize or suppress to a maximal extent GH and IGF-1 concentrations. The period of therapy in case of microadenoma would be at least 3 months (targets: biochemical improvement, reduced risk of disease's complications, perioperative risk reduction, inhibition of tumor growth). The period of therapy in case of macroadenoma would be at least 6 months, until maximal possible reduction of GH and IGF-1 concentrations (targets: tumor shrinkage, biochemical improvement, reduced risk of disease's complications, perioperative risk reduction). Using an uniform approach in a group, as numerous as possible, of treated patients would allow objective evaluation of long-term efficacy of the treatment. 相似文献
108.
P. J. Lewi 《Bulletin of mathematical biology》1965,27(3):271-280
Volume elasticity of the arterial system and its component parts is developed starting from a Windkessel*-model, which is defined in 4 points. Emphasis is laid on the simplicity of the derived equations and accessibility to experimental verification. The theory is an extension of earlier work achieved by Wetterer and Pieper (1953), who introduced an essentially physical method for the indirect determination of volume elasticity in situ, by creating forced sinusoidal oscillations in the arterial system, using a special pump operated at a considerably lower frequency than the mean heart frequency. The elegance of both experimental technique and the derived equations incited us to investigate the mathematical foundation and possible generalization of the method. 相似文献
109.
Relative efficacies of indole antioxidants in reducing autoxidation and iron-induced lipid peroxidation in hamster testes 总被引:2,自引:0,他引:2
Increased iron stores are associated with free radical generation and carcinogenesis. Lipid peroxidation is involved in DNA damage, thus indirectly participating in the early steps of tumor initiation. Melatonin and structurally related indoles are effective in protecting against oxidative stress. The aim of the study was to compare the relative efficacies of melatonin, N-acetylserotonin (NAS), indole-3-propionic acid (IPA), and 5-hydroxy-indole-3-acetic acid (5HIAA) in altering basal and iron-induced lipid peroxidation in homogenates of hamster testes. To determine the effect of the indoles on the autoxidation of lipids, homogenates were incubated in the presence of each agent in concentrations of 0.0, 0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0, 2.0, 2.5, or 5.0 mM. To study their effects on induced lipid peroxidation, homogenates were incubated with FeSO(4) (30 microM + H(2)O(2) (0.1 mM) + each of the indoles in the same concentrations as above. The degree of lipid peroxidation was expressed as concentrations of malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) per mg protein. The indoles decreased both basal and iron-related lipid peroxidation in a concentration-dependent manner. Melatonin reduced basal MDA + 4-HDA levels when used at the concentrations of 0.25 mM or higher, and prevented iron-induced lipid peroxidation at concentrations of 1.0, 2.0, 2.5, or 5.0 mM. The lowest effective concentrations of NAS required to lower basal and iron-related lipid peroxidation were 0.05 mM and 0.25 mM, respectively. IPA, only when used in the highest concentrations of 2.5 mM or 5 mM inhibited basal lipid peroxidation levels and it was ineffective on the levels of MDA + 4-HDA due to iron damage. 5HIAA reduced basal lipid peroxidation when used at concentrations of 0.25 mM or higher, and it prevented iron-induced lipid peroxidation only at the highest applied concentration (5 mM). In conclusion, melatonin and related indoles at pharmacological concentrations protect against both the autoxidation of lipids as well as induced peroxidation of lipids in testes. In doing so, these agents would be expected to reduce testicular cancer that is initiated by products of lipid peroxidation. 相似文献
110.