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101.
102.
Moult J Fidelis K Zemla A Hubbard T Tramontano A 《Structure (London, England : 1993)》2002,10(3):291-2; discussion 292-3
103.
Mikuliszyn R Kowalski W Kowalczuk K 《Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology》2002,9(1):P333-P334
There are many factors affecting pilots' +Gz-tolerance. Recently, attention of the aviation community has been focused on lay-off and it's impact on +Gz-tolerance. Pilots of the Polish Air Force (PAF) have dealt with that problem for several years now. The aim of the study was to provide insight on how lay-off periods with different duration impact +Gz-tolerance. Methods: 95 male jet pilots from the PAF participated in the study. Every one had at least two weeks lay-off period (non-medical reasons). Subjects were divided into four groups according to the length of lay-off period (2-4 weeks; 5-13 weeks; 14-26 weeks; 27-154 weeks), All pilots were subjected to a centrifuge exposure in GOR (0.1 G/s) or ROR (1.0 G/s) profiles, depending on the pre-lay-off exposure. Post-lay-off exposures were carried out directly after lay-off. 18 jet pilots without any lay-off constituted the control group. Results: The difference between pre- and post-lay-off G-tolerance limit (-0,93 +/- 0,53) was statistically significant (p<0.01) only for one group, where lay-off period ranged between two and four weeks. No statistically significant differences were found where influence of other factors like total and yearly flight hours, heart rate gain (AHR) or physical activity measured as maximal oxygen intake were considered. Conclusions: 2-4 weeks of lay-off period decreases +Gz tolerance is statistically significant manner. Subsequent increase of lay-off period does not result in mean tolerance changes for group, however in certain individuals critical decrement of +Gz tolerance occurs. Total and last year flying hours, physical fitness does not modify impact of lay-off period on +Gz tolerance. 相似文献
104.
Elongation factor 2 as a target for selective inhibition of protein synthesis in vitro by the novel aromatic biasamidine 总被引:7,自引:0,他引:7
Gajko-Galicka A Bielawski K Sredzinska K Bielawska A Gindzienski A 《Molecular and cellular biochemistry》2002,230(1-2):159-164
By the formation of cGMP the NO-sensitive guanylyl cyclase plays a key role within the NO/cGMP signaling cascade involved in vascular regulation and neurotransmission. The prosthetic heme group of the enzyme acts as the NO sensor, and binding of NO induces conformational changes leading to an up to 200-fold activation of the enzyme. The unexpected fast dissociation half-life of NO of a few seconds is fast enough to account for the deactivation of the enzyme in biological systems. YC-1 and its analogues acting as NO sensitizers uncovered a new pharmacologically and conceivably physiologically relevant regulatory principle of the enzyme.Two existing isoforms of the heterodimeric guanylyl cyclase (11, 21) are known that are functionally indistinguishable. Up to now, the NO-sensitive guanylyl cyclase has been considered as a soluble enzyme. However, recent evidence about the 21 isoform interacting with a PDZ domain of the postsynaptic scaffold protein PSD-95 suggests that the 2 subunit directs a membrane association of this isoform. The interaction with PSD-95 locates the 21 isoform in close proximity to the NO-generating NO synthase thereby enabling the NO sensor to respond to locally raised NO concentrations. 相似文献
105.
The ribonucleic acids (RNA) form highly folded structures, which behind the helical fragments contain several secondary and tertiary structural motives. All of them have an influence on thermodynamic stability of the RNA. The 5'- and 3'-dangling ends are one of those structural motives, which effect stability of the adjacent helixes. In this paper, we described the influence of 14 different modified nucleotides, placed as 3'-dangling ends, on thermal stability of the RNA duplexes. Collected data demonstrate that: (i) 5-substituents of the uridine have an impact on the 3'-dangling end effect and the largest changes were observed for 5-chloro, bromo and methyl substituents; (ii) position of the methyl group within the uracil residue affect the thermal stability of the duplex; (iii) increasing a size of the heterocycle base placed as the 3'-terminal unpaired nucleotide enhances stabilization of duplexes. 相似文献
106.
Lipopolysaccharide from Proteus mirabilis O29 induces changes in red blood cell membrane lipids and proteins 总被引:2,自引:0,他引:2
Gwoździński K Pieniazek A Kaca W 《The international journal of biochemistry & cell biology》2003,35(3):333-338
Alterations in red blood cell (RBC) plasma membranes, i.e. in lipids and proteins, and osmotic fragility of these cells after treatment with Proteus mirabilis O29 endotoxin (lipolysaccharide (LPS)) were examined using a spin labelling method. At the highest concentration of LPS, insignificantly decreased fluidity of membrane lipids was observed. Changes in conformation of membrane proteins were determined by two covalently bound spin labels, 4-maleimido-2,2,6,6-tetramethylpiperidine-1-oxyl (MSL) and 4-iodoacetamido-2,2,6,6-tetramethylpiperidine-1-oxyl (ISL). The analysis of spectra of MSL and ISL showed modifications in membrane proteins in red blood cells treated with the highest concentration of lipopolysaccharide. On the other hand, in the case of isolated membranes, disturbances in membrane were observed for all concentrations of LPS. The alterations in membrane lipids and proteins are paralleled in a significant rise in osmotic fragility of RBCs upon endotoxin treatment. These results provide experimental evidence that P. mirabilis O29 LPS causes deleterious changes in membranes of human red blood cells. They show that action of lipopolysaccharide mainly concerns the membrane cytoskeleton. 相似文献
107.
108.
Koceva-Chyła A Gwoździński K Kochman A Stolarska A Jóźwiak Z 《Cellular & molecular biology letters》2003,8(1):179-183
Protection from doxorubicin-induced lipid peroxidation in vivo by two pyrroline and pyrrolidine nitroxides, Pirolin, PL, and Pirolid, PD, was examined in the heart tissue of rats treated with this drug. The level of lipid peroxidation was estimated on the basis of MDA content. A considerable (three-fold) increase in the MDA amount was found in heart homogenates from rats injected with doxorubicin, whereas no significant changes in MDA content compared to control were observed in cardiomyocytes treated with the nitroxides (Pirolin or Pirolid) only. Pirolin injected simultaneously with doxorubicin showed antioxidative effect and markedly attenuated lipid peroxidation in the heart tissue caused by this drug. In contrast to Pirolin, structurally related Pirolid was ineffective in the protection of heart myocytes from DOX-induced lipid peroxidation. 相似文献
109.
Bryl K 《Cellular & molecular biology letters》2003,8(2):285-296
Rhodopsins are currently known to belong to two distinct protein families. The visual rhodopsins, found in eyes throughout the animal kingdom, are photosensory pigments. Archaeal rhodopsins, found in extreme halophiles, function as light-driven proton pumps (bacteriorhodopsins), chloride ion pumps (halorhodopsins), or photosensory receptors (sensory rhodopsins). Light absorption by rhodopsins triggers their characteristic photoconversion extending into the (milli)second time range. There are three main paradigms of rhodopsins photoconversion. (1) Initiation of the trans-cis isomerization is the very primary consequence of light absorption. (2) Rhodopsins store light energy via the charge-separation mechanism (the charge of Schiff base is separated from its counterion). (3) Full trans-cis isomerization of the chromophore is a prerequisite for the full biological activity of rhodopsins. These paradigms will be questioned. 相似文献
110.
Okon K Szumera A Papla B Pietkun I Zdunczyk A Rucinska M Skotnicki AB Stachura J 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》2003,25(4):227-234
OBJECTIVE: To analyze cytologic and histologic parameters in bone marrow trephine biopsy in an attempt to define heterogeneity of hairy cell leukemia cells. STUDY DESIGN: The study group consisted of 28 trephine biopsies. Immunohistochemistry for CD20 antigen was used. Image processing and measurements were performed with AnalySIS 3.0 image analysis system (Soft Imaging System GmbH, Germany) and custom built programs. For planimetric measurements of nuclei, automatic segmentation was implemented. The measured parameters were: surface area, perimeter, minimum, mean and maximum diameter, and a set of form factors. Relative volumes of bone trabeculae, adipose tissue, hematopoietic tissue and neoplastic infiltrate were assessed by the point counting method. Nuclear volume was measured by the point sampled intercept method. Bone marrow fibrosis was assessed using a curvilinear line test system. RESULTS: Significant variability of cell nuclei was found, and their classification into 3 types was possible. The relative frequency of those types was different in various cases and allowed subdivision of cases into 3 groups that differed in some clinical and histologic manifestations. CONCLUSION: The present study demonstrated the heterogeneity of cell populations of hairy cell leukemia. 相似文献