Production of TNF-alpha and TNF-beta by staphylococcal enterotoxin A activated human T cells

Staphylococcal enterotoxin at concentrations of less than 1 pg/ml induces significant TNF activity in human peripheral blood T cells and monocytes. Maximal TNF activity is routinely detected after 48 to 72 h of culture. IL-2 and IL-4 were both growth promoting for human T cells but only IL-2 could efficiently induce TNF production. The production of TNF-alpha and TNF-beta differed greatly in kinetics. An early intracytoplasmatic production of TNF-alpha after 6 h was detected in both monocytes and T cells whereas a late production of TNF-beta (lymphotoxin) after 48 h, occurred in the T cell population. Induction of TNF-alpha and TNF-beta production by Staphylococcal enterotoxin requires the presence of both monocytes and T cells. The CD4+45R- but not CD4+45R+ and CD8+ cells supported TNF-alpha production in monocytes. The main lytic component from Staphylococcal enterotoxin-activated mononuclear cells is TNF-beta. CD4+ and CD8+ T cells produced about equal amounts of biologically active TNF into the culture supernatants but a fourfold higher frequency of TNF-beta producing cells was demonstrated among CD4+ vs CD8+ cells. The CD4+45R- T cell subset was an efficient producer of TNF-beta and IFN-gamma whereas the CD4+45R+ T cell subset produced significant amounts of TNF-beta but only marginal amounts of IFN-gamma.     

Molecular organization of human plasma alpha 2-macroglobulin and its trypsin complexes. A small-angle x-ray scattering investigation

The molecular organization of human plasma alpha 2-macroglobulin (alpha 2M), and its 1:1 and 1:2 trypsin complexes, have been investigated using the small-angle x-ray scattering method. All the experimental data can be explained by the same basic model, consisting of three oblate-shaped domains arranged in a sandwich-like structure. Each of the larger peripheral domains consists of two parallel elliptic cylinders associated side-by-side, whereas the smaller central domain consists of just one elliptic cylinder. In the native molecule the three domains are separated by regions of low protein density. Upon trypsin binding the dimensions of the four peripheral cylinders remain unchanged, but their positioning in space is reorganized so that the whole molecule becomes more compact. The model thus offers a plausible explanation for the mechanism of inactivating of the protease by entrapping it between the two larger domains. By comparing the shape and dimensions of the total molecule with those determined for the half-molecular fragment, obtained after reducing the intersubunit disulfide bonds, we propose that the fragment consists of just one of the peripheral domains plus half of the central domain. Different projections of the model are consistent with the electron micrographs of alpha 2M given in the literature. The model can also explain many of the physical and chemical properties recorded for alpha 2M and its protease complexes.     

Estimation of the effect of photoinhibition on the carbon gain in leaves of a willow canopy

The occurrence of photoinhibition of photosynthesis in leaves of a willow canopy was examined by measuring the chlorophyll-a fluorescence ratio of F _V/F _M (F_M is the maximum fluorescence level of the induction curve, and F_V is the variable fluorescence, F _V=F _M–F ₀, where F₀ is the minimal fluorescence). The majority of the leaves situated on the upper parts of peripheral shoots showed an afternoon inhibition of this ratio on clear days. This was the consequence of both a decrease in F _M and a rise in F _O. In the same leaves the diurnal variation in intercepted photosynthetic photon flux density (PPFD) was monitored using leaf-mounted sensors. Using the multivariate method, partial least squares in latent variables, it is shown that the dose of PPFD, integrated and linearly weighted over the last 6-h period, best predicts photoinhibition. Photoinhibition occurred even among leaves that did not intercept PPFDs above 1000 mol·m^–2·s^–1. Exposure of leaves to a standard photoinhibitory treatment demonstrated that the depression in the F _V/F _M ratio was paralleled by an equal depression in the maximal quantum yield of CO₂ uptake and a nearly equal depression in the rate of bending (convexity) of the light-response curve of CO₂ uptake. As a result, the rate of net photosynthesis is depressed over the whole natural range of PPFD. By simulating the daily course in the rate of net photosynthesis, it is estimated that in the order of one-tenth of the potential carbon gain of peripheral willow shoots is lost on clear days as a result of photoinhibition. This applies to conditions of optimal temperatures. Photoinhibition is even more pronounced at air temperatures below 23° C, as judged from measurements of the F_V/F_M ratio on clear days: the afternoon inhibition of this ratio increased in a curvilinear manner from 15% to 25% with a temperature decrease from 23° to 14° C.Abbreviations and Symbols F_O minimum fluorescence - F_V variable fluorescence - F_M maximum fluorescence - PLS partial least squares in latent variables - PPFD photosynthetic photon flux density - VPD water vapour-pressure deficit This study was supported by the Swedish Natural Science Research Council. We are indebted to Dr. Jerry Leverenz (Department of Plant Physiology, University of Umeå, Sweden) for guidance with the modelling of the photosynthesis data.     

One of the major sulphated proteins secreted by rat hepatocytes contains low-sulphated chondroitin sulphate.

When isolated hepatocytes are incubated with 35SO4(2-), a specific set of secretory proteins is labelled. One of these proteins is electrophoretically heterogeneous, with an apparent molecular mass of 35-45 kDa [Marcks von Würtemberg & Fries (1989) Biochemistry 28, 4088-4093]. Here we report that treatment with chondroitinase ABC converted the broad electrophoretic band of this protein, with a 50-60% loss of radioactivity, into a relatively homogeneous band with a molecular mass of 28 kDa. Size determination by gel chromatography of the protein's oligosaccharide chain (released by alkali treatment) indicated that it contained about 40 hexose units. Similar analysis of the enzyme-resistant oligosaccharide chain remaining linked to the protein after chondroitinase ABC treatment indicated a size of between six and eight hexose units. These observations suggest that the protein's oligosaccharide chain carries only three or four sulphate groups, of which one or two are located close to the polypeptide chain. Consistent with this hypothesis, the free oligosaccharide behaved like a low-sulphated glycosaminoglycan upon ion-exchange chromatography.     

An in vitro bioassay for quantitation of human interferons by measurements of antiproliferative activity on a continuous human lymphoma cell line

Interferons have, in addition to their antiviral effects, been shown to possess several non-antiviral activities. In this study, an in vitro bioassay for interferon alpha (IFN-alpha) preparations based on their antiproliferative effect in cultured Daudi cells has been developed. Briefly, about 10(5) cells per ml treated with different concentrations of IFN were incubated under standard culture conditions for 3 days. Two different end points, i.e. incorporation of [3H]thymidine and final cell density, were used and responses were evaluated according to established pharmacopoeial principles for quantification of biomolecules. Both methods gave similar results. However, measurement of final cell density yielded the most precise results. The proposed assay, with an effective assay range of 1-10 IU/ml (approximately 0.2-2 x 10(-12)M, had a high sensitivity and precision as well as a good reproducibility. Compared with antiviral assays, it is less resource demanding. In conclusion, the in vitro bioassay described is well suited for potency determinations of IFN-alpha and probably also IFN-beta preparations.     

Species composition of dabbling duck assemblages: ecomorphological patterns compared with null models

Ecomorphological patterns of breeding dabbling duck (Anas spp.) assemblages were studied in six regions in northern Europe. Observed spacings among species in terms of bill lamellar density and body length were compared with expected spacings based on null models incorporating different levels of constraints (regional species pools, species relative abundances, lake size and habitat requirements of species). Deviations of observed spacings from expected ones were compared with prey abundance and prey size diversity in the lakes. Observed spacings in terms of body length, but not in terms of bill lamellar density, were greater than expected on the basis of null models. The most abundant species were generally relatively more different than less abundant species in terms of body length but not in terms of bill lamellar density. Deviations between observed and expected spacings in terms of body length were more like those predicted by the competition hypothesis in lakes with low food abundance than in lakes with high food abundance. Patterns in bill lamellar spacings were not related to food abundance nor to food size diversity. In general, patterns in body length spacings were consistent with the competition hypothesis whether the null model used in comparisons was constrained or not.     

Shoulder muscle load and muscle fatigue among industrial sewing-machine operators

Physiological responses to physical work were assessed for 29 female industrial sewing-machine operators during an 8-h working day under ordinary working conditions. During sewing-machine work, the average (left and right) static load in the trapezius muscle was 9% of the maximal electromyogram (EMG) amplitude (% EMG_max), while the average mean load was 15% EMG_max, and the average peak load was 23% EMG_max. The static load level was unrelated to the muscle strength of the sewing-machine operators, which for the group as a whole was within the normal range. The load levels remained unchanged during the working day, while changes in the EMG mean power frequency and zero crossing frequency rate occurred, both indicating the development of muscle fatigue in left and right trapezius muscle during the working day. In line with this, the rating of perceived exertion in the shoulder and neck region increased during. the working day. Dividing the group of sewing-machine operators into two groups, those with the highest frequency and those with the lowest frequency of shoulder/neck troubles showed that the former group had significantly lower muscle strength, despite the fact that no differences in the surface EMG during sewing were found between the two groups. It was concluded that industrial sewing-machine work involves a pattern of shoulder muscle activity which induces fatiguing processes in the shoulder and neck regions. Furthermore, since the static shoulder muscle load was independent of muscle strength, factors other than working posture may be of significance for the static shoulder muscle load.     

Psychological complications after stillbirth--influence of memories and immediate management: population based study.

OBJECTIVE--To identify factors that may predict long term psychological complications among women who have had a stillborn child. DESIGN--Nationwide population based study using epidemiological methods. SUBJECTS--380 subjects and 379 controls who had had a stillborn or non-deformed live child in Sweden in 1991. RESULTS--Information was provided by 636 (84%) women. The ratio (95% confidence interval) of proportions of women with symptoms related to anxiety above the 90th centile for women who had had a stillborn child compared with those who had not was 2.1 (1.2 to 3.9). An interval of 25 hours or more from the diagnosis of death in utero to the start of delivery gave a ratio of 4.8 (1.5 to 15.9). The ratio was 2.3 (1.1 to 5.3) for not seeing the child as long as the mother had wished and 3.1 (1.6 to 6.0) for no possession of a token of remembrance. CONCLUSION--It is advisable to induce the delivery as soon as feasible after the diagnosis of death in utero. A calm environment for the woman to spend as much time as she wants with her stillborn child is beneficial, and tokens of remembrance should be collected.