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141.
Bartels F Fernández S Holtel A Timmis KN de Lorenzo V 《The Journal of biological chemistry》2001,276(20):16641-16648
A protein mixture containing two major components able to catalyze a beta-recombination reaction requiring nonspecific DNA bending was obtained by fractionation of a Pseudomonas putida extract. N-terminal sequence analysis and genomic data base searches identified the major component as an analogue of HupB of Pseudomonas aeruginosa and Escherichia coli, encoding one HU protein variant. The minor component of the fraction, termed HupN, was divergent enough from HupB to predict a separate DNA-bending competence. The determinants of the two proteins were cloned and hyperexpressed, and the gene products were purified. Their activities were examined in vitro in beta-recombination assays and in vivo by complementation of the Hbsu function of Bacillus subtilis. HupB and HupN were equally efficient in all tests, suggesting that they are independent and functionally redundant DNA bending proteins. This was reflected in the maintenance of in vivo activity of the final sigma54 Ps promoter of the toluene degradation plasmid, TOL, which requires facilitated DNA bending, in DeltahupB or DeltahupN strains. However, hupB/hupN double mutants were not viable. It is suggested that the requirement for protein-facilitated DNA bending is met in P. putida by two independent proteins that ensure an adequate supply of an essential cellular activity. 相似文献
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A De Lorenzo R P Sorge N Candeloro C Di Campli G Sesti R Lauro 《Canadian journal of physiology and pharmacology》1999,77(1):17-21
During treatment of patients with non-insulin-dependent diabetes mellitus, there may be marked body weight loss. Therefore, body composition should be monitored to check for a decrease in fat mass alone, without an excessive decrease of both fat-free mass and total body water. Accordingly, it is useful to monitor the hydration of these patients. One method that allows us to check the status of body hydration is the multifrequency bioelectric impedance analysis (MFBIA). It makes use of formulas that estimate total body water on the basis of the concept that the human body may be approximated to a cylinder of length equal to body height. In normal subjects body water estimates are sufficiently accurate, but in obese subjects the true hydration status may be overestimated. In this report, we describe the accuracy of mathematical models previously described in the literature, and correct for the overestimation of total body water in obese subjects by means of a new equation based on a new model. The coefficients for each model have been recalculated by the weighing of our sample in order to test the accuracy of estimates obtained with the equations. This new model includes both body volume and two impedances at appropriate frequencies useful for identifying two terms strictly related to extra- and intra-cellular water. The new formulas do not include body weight, but they include the body volume, a parameter more closely related to the biophysical reference model. Fifty-five overweight females, body mass index ranging from 26.8 to 50.2 kg/m2, were enrolled in the study. The proposed equations, taking advantage of two impedance values at appropriate frequencies, better predict total body water in obese women. This was particularly evident when the results obtained with the multifrequency bioelectric impedance analysis and deuterium isotopic oxide dilution method were compared. Although this last method is considered the "gold standard," it is not suitable for use in routine clinical practice. In conclusion, evaluation of total body composition by means of bioelectric impedance analysis might be included in programs for the prevention of non-insulin-dependent diabetes and for monitoring weight loss during overt pathology. 相似文献
145.
A dynamometric hubset that measures the two ground contact force components acting on a bicycle wheel in the plane of the bicycle during off-road riding while either coasting or braking was designed, constructed, and evaluated. To maintain compatibility with standard mountain bike construction, the hubs use commercially available shells with modified, strain gage-equipped axles. The axle strain gages are sensitive to forces acting in the radial and tangential directions, while minimizing sensitivity to transverse forces, steering moments, and variations in the lateral location of the center of pressure. Static calibration and a subsequent accuracy check that computed differences between applied and apparent loads developed during coasting revealed root mean squared errors of 1 percent full-scale or less (full-scale load = 4500 N). The natural frequency of the rear hub with the wheel attached exceeded 350 Hz. These performance capabilities make the dynamometer useful for its intended purpose during coasting. To demonstrate this usefulness, sample ground contact forces are presented for a subject who coasted downhill over rough terrain. The dynamometric hubset can also be used to determine ground contact forces during braking providing that the brake reaction force components are known. However, compliance of the fork can lead to high cross-sensitivity and corresponding large (> 5 percent FS) measurement errors at the front wheel. 相似文献
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147.
Protein kinase Cdelta targets mitochondria, alters mitochondrial membrane potential, and induces apoptosis in normal and neoplastic keratinocytes when overexpressed by an adenoviral vector 下载免费PDF全文
Inactivation of protein kinase Cdelta (PKCdelta) is associated with resistance to terminal cell death in epidermal tumor cells, suggesting that activation of PKCdelta in normal epidermis may be a component of a cell death pathway. To test this hypothesis, we constructed an adenovirus vector carrying an epitope-tagged PKCdelta under a cytomegalovirus promoter to overexpress PKCdelta in normal and neoplastic keratinocytes. While PKCdelta overexpression was detected by immunoblotting in keratinocytes, the expression level of other PKC isozymes, including PKCalpha, PKCepsilon, PKCzeta, and PKCeta, did not change. Calcium-independent PKC-specific kinase activity increased after infection of keratinocytes with the PKCdelta adenovirus. Activation of PKCdelta by 12-O-tetradecanoylphorbol-13-acetate (TPA) at a nanomolar concentration was lethal to normal and neoplastic mouse and human keratinocytes overexpressing PKCdelta. Lethality was inhibited by PKC selective inhibitors, GF109203X and Ro-32-0432. TPA-induced cell death was apoptotic as evidenced by morphological criteria, TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) assay, DNA fragmentation, and increased caspase activity. Subcellular fractionation indicated that PKCdelta translocated to a mitochondrial enriched fraction after TPA activation, and this finding was confirmed by confocal microscopy of cells expressing a transfected PKCdelta-green fluorescent protein fusion protein. Furthermore, activation of PKCdelta in keratinocytes altered mitochondrial membrane potential, as indicated by rhodamine-123 fluorescence. Mitochondrial inhibitors, rotenone and antimycin A, reduced TPA-induced cell death in PKCdelta-overexpressing keratinocytes. These results indicate that PKCdelta can initiate a death pathway in keratinocytes that involves direct interaction with mitochondria and alterations of mitochondrial function. 相似文献
148.
Black seabream, Spondyliosoma cantharus, caught off the Canary Islands is characterized by a protogynous hermaphroditism. The size range of the catches is between 8 and 40cm, with a main distribution between 16 and 24cm. The mean length of the individuals shows an increase with increasing depth. Males:females ratio is unbalanced in favour of females (1:2.18). The reproductive season extends from late autumn to mid spring, with a peak in spawning activity in January–February. A dichromatism is found between males and females during the spawning season. Males reach maturity at a larger total length, 22.7cm (3 years old), than females, 17.3cm (2 years old). Morphometric relationship between length and mass for the whole population is described by the parameters: a=0.00732, and b=3.24747. Otoliths age readings indicate that the exploited population consists of eleven age groups (0–X years), including a very high proportion of individuals between 2 and 3 years old. The von Bertalanffy growth parameters for the whole population are: L=43.35cm, k=0.24 year–1, and t0=–0.11 year. The rates of total, natural and fishing mortality are 1.36, 0.52 and 0.84 year–1, respectively. The length at first capture is 16.8cm. The exploitation rate indicates that the stock is overfished. 相似文献
149.
Microbial activity in spent nuclear fuel pools which contain ultrapure and radioactive water has been previously observed. The aim of the present research was to isolate and identify the microorganisms attached to the nuclear pool wall of a Spanish nuclear power plant. Amplification of 16S rDNA fragments from the culturable microorganisms by PCR using universal primers for the domain 'Bacteria', followed by Denaturing Gradient Gel Electrophoresis analysis revealed the presence of six different bacteria. The complete gene for 16S rDNA of each one was sequenced and identified as belonging to three different phylogenetic groups, viz. beta-Proteobacteria, Actinomycetales and the Bacillus/Staphylococcus group. A fungus was also found and identified as Aspergillus fumigatus by sequencing the D2 region of the large subunit rDNA gene. The isolation of these microorganisms in oligotrophic and radioactive conditions is of great interest due to the possibility of their use in bioremediation processes of radionuclide-contaminated environments. 相似文献
150.
Marangoni A Aldini R Sambri V Giacani L Di Leo K Cevenini R 《FEMS immunology and medical microbiology》2004,40(3):187-191
Stimulation of isolated rat Kupffer cells by viable Leptospira interrogans, Treponema pallidum and Borrelia garinii elicited cellular responses resulting in the release of different tumor necrosis factor alpha (TNF-alpha) levels, depending on the spirochetes. L. interrogans induced TNF-alpha levels higher than those achieved with B. garinii and T. pallidum (in this order), but lower than the levels achieved with lipopolysaccharide (LPS). In contrast to L. interrogans, pretreatment of borreliae and treponemes with polymyxin B did not substantially diminish the ability of B. garinii and T. pallidum to stimulate Kupffer cells. Purified T. pallidum lipoproteins TpN47, TmpA, TpN15-TpN17, and B. garinii OspA induced TNF-alpha responses comparable to that achieved by LPS. This response was almost insensitive to the action of polymyxin B. 相似文献