The effect of proteases on endothelial cell migration in vitro

This communication reports on the role of proteases in the migration of endothelial cells in vitro. Endothelial cell (EC) migration was assayed by wounding confluent monolayers of bovine aortic endothelial cells with a razor blade and counting the number of cells crossing the wound per unit time. Treatment with mitomycin C inhibited wound-induced proliferation of endothelial cells without affecting migration, indicating that in this assay migration could be measured independent of proliferation. Migration of endothelial cells in vitro in 10% serum was not affected by depletion of plasminogen, which inhibited plasmin production, or by various protease inhibitors: soybean trypsin inhibitor, Trasylol, E-amino caproic acid (EACA), ovalbumin, p-tpsyl-1-arginine-methyl ester (TAME), and benzamidine. However, migration and proliferation of endothelial cells in vitro was inhibited by acid-treated serum, a procedure commonly used to inactivate protease inhibitors. Migration of bovine smooth muscle cells, 3T3 cells and SV40-3T3 cells was inhibited by plasminogen-depleted serum; reconstitution with purified plasminogen reversed the depressed migration of only SV40-3T3. These results indicated that endothelial cell migration in vitro is not dependent on plasminogen, which may be another unique property of endothelial cells.     

The PPGMRPP repetitive epitope of the Sm autoantigen: Antigenic specificity induced by conformational changes. Application of the Sequential Oligopeptide Carriers (SOCs)

Summary The PPGMRPP sequence, found in several copies in the Sm and U1RNP autoantigens, is the main target of anti-Sm and anti-U1RNP antibodies in systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD) patient's sera. It is also recognized, to a lower extent, by anti-Ro/SSA and anti-La/SSB specificities. The PPGMRPP-NH₂ peptide amide and the PPGMRPP peptide, which is bound to a pentameric sequential oligopeptide carrier (SOC₅), were examined by¹H-NMR spectroscopy and ELISA assays, using sera from patients with autimmune rheumatic diseases. Among the three main conformers found for the free PPGMRPP, the extended one was also identified for PPGMRPP-NH₂ and (PPGMRPP)₅-SOC₅. This can be attributed to the absence of ionic interactions between the Arg-guanidinium and the carboxylate group in the amide and SOC₅-bound forms of the peptide. Immunoassays using sera from various specificities showed an enhanced anti-Sm and anti-U1RNP recognition of PPGMRPP-NH₂ and (PPGMRPP)₅-SOC₅, and lowering of the anti-Ro/SSA and anti-La/SSB reactivity. The presence of multiple conformers of free PPGMRPP may explain the unexpected cross-reactivity to the anti-Ro/La positive sera, while the prevalence of the extended conformation in PPGMRPP-NH₂ and (PPGMRPP)₅-SOC₅ is mainly responsible for the enhanced recognition from the anti-Sm and anti-U1RNP autoantibodies. it is concluded that the antigenic specificity of PPGMRPP-NH₂ and (PPGMRPP)₅-SOC₅ is mainly induced by conformational changes resulting from the conversion of the C-terminal carboxylate group to the amide form.     

Pattern profile analysis of hominid and chimpanzee hand bones

In a study designed to complement morphological research on hominid hand bones, length and width measurements of the thumb, index, and middle rays were obtained from radiographs of modern human hands. These rays are primary in precision-gripping postures and are therefore the ones most relevant for investigating evolutionary changes in fine manipulation. Pattern profile analysis allows individuals or samples to be plotted against a reference sample in standard deviation units, or Z-scores. It provides an indication of how different measurements are from modern human averages, while taking into consideration the degree of variation present within modern human samples. A pattern profile for chimpanzees is clearly distinct from humans but quite similar to that of a bonobo, demonstrating the promise of pattern analysis. Partial pattern profiles of several of the more complete early hominid bones from Hadar, Swartkrans, and Olduvai (O.H. 7) are presented and compared. Hadar bones are long and wide at midshaft relative to articular widths; both body-size effects and functional differences are likely. Thumb distal phalanges from Swartkrans and Olduvai both have relatively small base widths, but they differ in other proportions. Two first metacarpals from Swartkrans show distinct patterns. The profiles of La Ferrassie I and Shanidar IV show the characteristically large Neanderthal distal phalanges. Profiles of Skhūl IV and P?edmost III are alike in some regions with reference to modern North American white males, though they are less similar overall than are those of the two Neanderthals. © 1995 Wiley-Liss, Inc.     

Different isometric force - [Ca2+] relationships in slow and fast twitch skinned muscle fibres of the rat

Skinned muscle fibres prepared from fast and slow twitch muscles of rat have been activated in Ca²⁺-buffered solutions using a new activation procedure (Moisescu, D.G. and Thieleczek, R. (1978) J. Physiol. 275, 241–262). The results indicate that (i) the Ca²⁺ activation curve is less steep for slow fibres, (ii) physiologically relevant force levels are attained considerably faster at constant [Ca²⁺] in fast fibres, and (iii) active force becomes noticeable at lower [Ca²⁺], but reaches saturation at higher [Ca²⁺] for slow fibres.     

NMR assignment of the N-terminal region of human La free and in complex with RNA

¹H, ¹⁵N and ¹³C chemical shift assignments are presented for the N-terminal region of human La protein, in the apo and 5′-UUUU RNA-bound state. Secondary structure analysis shows conformational changes in the interdomain linker upon complex formation.     

High foliicolous lichen alpha-diversity on individual leaves in Costa Rica and Amazonian Ecuador

Two individual, dicotyledoneous leaves (125 and 98 cm² in size) and one composed palm leaf (c. 6800 cm² in size), gathered at La Selva Biological Station, Costa Rica, and Jatun Satcha Biological Station, Amazonian Ecuador, were screened for small-scale foliicolous lichen diversity. On the dicotyledoneous leaf from Costa Rica, 49 lichens and one lichenicolous fungus were found, while a comparable leaf from Ecuador revealed 46 lichens and two lichenicolous fungi. The palm leaf yielded 81 lichens and one lichenicolous fungus. This is the highest alpha-diversity so far reported for foliicolous lichens on individual leaves and invites for comparison with tree diversity in tropical rain forests. Due to the high proportion of species represented by a single thallus, the taxonomic diversity of lichens on individual leaves (or trees in selected plots) cannot be self-supporting, but reflects a high degree of dispersion or entropy within the community of which the individual leaf (or selected plot) is part. Diversity is therefore fractal, showing similar patterns at different scales, each part of a given community reflecting the entire community. Thus, mechanisms that result in high small-scale diversity must be looked for at the community level.     

The butterflies and birds of Madeira and La Gomera: taxon cycles and human influence

Analyses of the habitat distributions and densities of Madeiran and La Gomeran butterflies and birds are used to test the predictions of the taxon cycle hypothesis. The predictions are as follows: recent colonists should occupy more habitats and be found at higher densities than endemic species or sub-species; colonists should predominate in the marginal habitats on the islands.
The distributions of Madeiran and La Gomeran birds and butterflies do not conform to those predicted by the taxon cycle. Neither do the densities of the bird and butterfly species on either island. There is some evidence that recent colonizers occupy marginal habitats but we suggest that it is difficult to draw conclusions when man has greatly influenced the nature of the islands' habitats.     

Chain heterogeneity in the methemoglobin-azide equilibrium.

The absorption spectra of solutions of methemoglobin partially saturated with azide were resolved into the best fitting components of two reference spectra (methemoglobin and methemoglobin azide) by a least-squares curve fitting operation. While good fits of sample spectra in terms of reference spectra were obtained as the extreme values of saturation were approached, poor fits were obtained in the middle region of fractional saturation. The distribution of residuals was markedly wavelength dependent, the greatest excursions being obtained at the isoabsorption point in the 0–100% azide difference spectrum of methemoglobin. The results are attributed to chain differences in an uncooperative tetramer.