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1.
2.
This paper reports a study of body height in the adult Jewish population of Israel, comparing native-born with immigrant groups. The sample tested included 1,411 men and 961 women, all clinically healthy according to the results of multiphasic screening. The phenomenon observed in other immigration-absorbing countries also holds for Israel: native Israelis are significantly taller than their immigrant counterparts. The findings were verified over different age and working activity strata, and thus may be taken to reflect the influence of better socioeconomic and environmental conditions on the bodily development of those born in Israel. 相似文献
3.
Carel J. Van Oss 《Cell biochemistry and biophysics》1989,14(1):1-16
The energy vs distance balance of cell suspensions (in the presence and in the absence of extracellular biopolymer solutions)
is studied, not only in the light of the classical Derjaguin-Landau-Verwey-Over-beek (DLVO) theory (which considered just
the electrostatic (EL) and Lifshitz-van der Waals (LW) interactions), but also by taking electron-acceptor/electron-donor,
or Lewis acid-base (AB) and osmotic (OS) interactions into account. Since cell surfaces, as well as many biopolymers tend
to have strong monopolar electron-donor properties, they are able to engage in a strong mutual AB repulsion when immersed
in a polar liquid such as water. The effects of that repulsion have been observed earlier in the guise of hydration pressure.
The AB repulsion is, at close range, typically one or two orders of magnitude stronger than the EL repulsion, but its rate
of decay is much steeper. In most cases, AB interactions are quantitatively the dominant factor in cell stability (when repulsive)
and in “hydrophobic interactions” (when attractive). OS interactions exerted by extracellularly dissolved biopolymers are
weak, but their rate of decay is very gradual, so OS repulsions engendered by biopolymer solutions may be of importance in
certain long-range interactions. OS interactions exerted by biopolymers attached to cells or particles (e.g., by glycocalix
glycoproteins), are very short-ranged and usually are negligibly small in comparison with the other interaction forces, in
aqueous media. 相似文献
4.
Analysis of epitope expression and the functional repertoire of recombinant complement receptor 2 (CR2/CD21) in mouse and human cells 总被引:9,自引:0,他引:9
J C Carel B Frazier T J Ley V M Holers 《Journal of immunology (Baltimore, Md. : 1950)》1989,143(3):923-930
We transfected human complement receptor 2 (CR2/CD21) cDNA containing eukaryotic expression constructs into CR2-negative mouse L cells and human K562 erythroleukemia cells. We subsequently selected stably transformed cells that expressed human CR2, as assessed by flow microfluorimetry analysis and immunoprecipitation of 125I-labeled surface membranes using the monoclonal anti-CR2 antibody, HB5. Utilizing flow microfluorimetry analysis, epitopes recognized by anti-CR2 mAb HB5, OKB7, B2, and four other anti-CR2 antibodies were detected on CR2 expressing transfectants but not parental cells. In addition, CR2 expressing transfected cells efficiently formed rosettes with sheep erythrocyte intermediates bearing human C3bi and C3d, but not C4b or C3b, consistent with the known ligand specificity of CR2. CR2 containing transfectants were also demonstrated to specifically bind EBV. Infection with EBV of CR2 expressing L cells and K562 cells resulted in mean expression of Epstein-Barr nuclear Ag (EBNA) at 48 h in 0.35% of CR2 expressing L cells and 3.7% of CR2 expressing K562 cells. Parental L cells and K562 cells did not express EBNA after EBV infection. These results indicate that CR2 alone is sufficient to transfer both C and EBV receptor functions to heterologous cells. In addition, expression of EBNA was found to be significantly higher in human K562 than mouse L cells, both expressing the same recombinant receptor. These results suggest that mechanisms other than CR2 binding lead to inefficient EBV infection and/or EBNA synthesis in mouse fibroblasts. 相似文献
5.
6.
Summary The hydraulic conductivity of rabbit gallbladder epithelium has been studied using a continuous volumetric method based on capacitance measurements. The time resolution for measuring osmotic flows is in the range of seconds. Volume flows have been induced by osmotic gradients between 0 and 100 mosmol. In this range the flow-force relation is linear and theP
f value is 9.3×10–3 cm/sec. After correction for solute polarization effects, theP
f value amounts to 0.05 cm/sec. The observed flow is constant between 5 sec up to 20 min after a sudden increase in the osmolarity of the mucosal solution. The wet weight of the gallbladder tissue decreases by 22% and increases by 30% during osmotic flows from serosa to mucosa and from mucosa to serosa, respectively. Volume flows induced by hydrostatic pressure gradients on the mucosal surface are linearly related to the driving forces between 0 and 40 mbar. TheP
f value is 0.15 cm/sec. The volume flows are constant between 2 sec and 15 min after pressure application. The flow-force relation for pressure gradients on the serosal surface is markedly nonlinear for gradients greater than 5 mbar. Below 5 mbar theP
f value is 4.5 cm/sec. From electrical measurements, e.g., resistance and streaming potentials, and from flux studies with inulin and polyethylene glycol 4000, it is concluded that hydrostatic and osmotic gradients are not comparable when they are applied to gallbladder epithelium. They induce volume flows across different pathways, e.g., osmosis predominantly across the cellular route and pressure filtration predominantly across paracellular routes. 相似文献
7.
Micheline Giphart-Gassler Carel Wijffelman John Reeve 《Journal of molecular biology》1981,145(1):139-163
This paper describes the identification and functional role of late gene products of bacteriophage Mu, including an analysis of the structural proteins of the Mu virion.In vitro reconstitution of infectious phage particles has shown that four genes (E, D, I, J) control the formation of phage heads and that a cluster of eight genes (K, L, M, N, P, Q, R, S) controls the formation of phage tails.Sodium dodecyl sulphate/polyacrylamide gel electrophoresis of Mu polypeptides synthesized in Escherichia coli minicells infected by Mu phages carrying amber mutations in various late genes has resulted in the identification of the products of gene C (15.5 × 103Mr); H (64 × 103Mr); F (54 × 103Mr); G (16 × 103Mr); L (55 × 103Mr); N (60 × 103Mr); P (43 × 103Mr) and S (56 × 103Mr). Minicells infected with λpMu hybrid phages and deletion mutants of Mu were used to identify polypeptides encoded by the V-β region of the Mu genome. These are the products of genes V, W or R (41.5 × 103Mr, and 45 × 103Mr); U (20.5 × 103Mr) and of genes located in the β region (24 × 103Mr (gpgin) and 37 × 103Mr (possibly gpmom)).Analytical separation of the proteins of the Mu virion revealed that it consists of a major head polypeptide with a molecular weight of 33 × 103, a second head polypeptide of 54 × 103 (gpF) and two major tail polypeptides with molecular weights of 55 × 103 and 12.5 × 103 (gpL and gpY, respectively). In addition, there are five minor components of the tail (including gpN, gpS and gpU) and approximately seven minor components of the head structure of the virion (including gpH). 相似文献
8.
9.
Carel J. van Oss 《Preparative biochemistry & biotechnology》2013,43(3):375-376
ABSTRACT Covalent structural information on membrane proteins is not easily acquired since it is difficult to obtain pure membrane proteins in sufficient quantities. We have therefore examined the Bio-Rad 491 prep cell continuous elution electrophoresis apparatus as a method for providing the quantities of purified , alpha and beta subunits from (Na.K)-ATPase required for these studies. Twenty-four milligrams of crude (Na.K)-ATPase preparation was applied to the prep cell which consisted of a 7% Laemmli separating gel 4.5 cm in length. The prep cell was Y run under constant power and continuous cooling conditions. Those fractions containing the beta subunit were combined and further purified by wheat germ agglutinin affinity"' chromatography. Fractions containing the alpha subunit were combined and did not require further purification. The identity and the degree of purity of the proteins obtained using this approach was assessed utilizing SDS-PAGE, amino acid analysis 375 Copyright 1993 by Marcel Dekker, Inc. * and N-tertninal sequencing. This simple and fast method provides approximately 1.8 milligrams of each purified subunit from 24 milligrams of relatively crude microsomes. Recovery of the alpha and beta subunits from the crude (Na.K)-ATPase preparation was estimated to be 28% and 81%, respectively. 相似文献
10.
Esther H. D. Carlitz Robert Miller Clemens Kirschbaum Wei Gao Daniel C. H?nni Carel P. van Schaik 《PloS one》2016,11(4)
Non-human primates face major environmental changes due to increased human impacts all over the world. Although some species are able to survive in certain landscapes with anthropogenic impact, their long-term viability and fitness may be decreased due to chronic stress. Here we assessed long-term stress levels through cortisol analysis in chimpanzee hair obtained from sleeping nests in northwestern Uganda, in order to estimate welfare in the context of ecotourism, forest fragmentation with human-wildlife conflicts, and illegal logging with hunting activity (albeit not of primates), compared with a control without human contact or conflict. Concerning methodological issues, season [F(2,129) = 37.4, p < 0.0001, r2 = 0.18] and the age of nests [F(2,178) = 20.3, p < 0.0001, r2 = 0.11] significantly predicted hair cortisol concentrations (HCC). With regard to effects of anthropogenic impacts, our results neither showed elevation of HCC due to ecotourism, nor due to illegal logging compared to their control groups. We did, however, find significantly increased HCC in the fragment group compared to chimpanzees living in a nearby intact forest [F(1,88) = 5.0, p = 0.03, r2 = 0.20]. In conclusion, our results suggest that hair cortisol analysis is a powerful tool that can help understanding the impact of anthropogenic disturbances on chimpanzee well-being and could be applied to other great ape species. 相似文献