Showing papers by "Stockholm University published in 1979"
TL;DR: The activities of some glutathione-metabolizing enzymes were observed to be 5-to 60-fold lower in lung tissue than in the liver, and that phenobarbital nor methylcholanthrene had a significant effect on the levels of reduced glutATHione in lung and liver.
3,842 citations
TL;DR: The crystal structure of Cs[VOF 3 ] · 1 2 H 2 O has been determined and refined on the basis of three-dimensional X-ray diffractometer data (MoKα radiation).
784 citations
TL;DR: It was concluded that process tracing data can be fruitfully used in studies of decision making but that such data do not release the researcher from the burden of constructing theories or models in relation to which the data must then be analyzed.
656 citations
TL;DR: An improved technique for bacterial direct counts, using fluorescent staining and epifluorescence microscopy, is presented and seasonal changes in frequency of dividing cells were found which covariated with the bacterial uptake of C-labeled phytoplankton exudates.
Abstract: Frequency of dividing cells is suggested to be an indirect measure of the mean growth rate of an aquatic bacterial community. Seasonal changes in frequency of dividing cells were found which covariated with the bacterial uptake of 14C-labeled phytoplankton exudates. Batch and continuous culture growth experiments, using brackish water bacteria in pure and mixed enrichment cultures, were performed to establish a relationship between frequency of dividing cells and growth rate. An improved technique for bacterial direct counts, using fluorescent staining and epifluorescence microscopy, is presented. Based on a 6-month survey in a coastal area of the Baltic Sea, the bacterial production in the photic zone is estimated. Compared to the total primary production in the area, the bacterial population during this period utilized approximately 25% of the amount of carbon originally fixed by the primary producers.
437 citations
TL;DR: The release of dissolved organic carbon from phytolankton during photosynthesis, and the utilization of this carbon by planktonic bacteria, was studied using 14CO2 and selective filtration and in situ for estimation of annual dynamics.
Abstract: The release of dissolved organic carbon (DOC) from phytolankton during photosynthesis, and the utilization of this carbon by planktonic bacteria, was studied using 14CO2 and selective filtration. Natural sea water samples from a coastal area of the Northern Baltic Sea were incubated in the laboratory for detailed studies, and in situ for estimation of annual dynamics. In a laboratory incubation (at +1°C) the concentration of 14C-labelled dissolved organic carbon increased for about 2 h and then reached a steady state, representing about 0. 1% of the total DOC. Labelled organic carbon in the phytoplankton and bacterial fractions continued to increase almost linearly. The continuous increase in the bacterial fraction is thought to represent almost instantaneous utilization of the DOC released from the phytoplankton during photosynthesis. As an annual average, in 4 h in situ incubations, about 65% of the labelled organic carbon was found in the phytoplankton fraction (>3 μm), about 27% in the bacterial fraction (0.2 to 3 μm) and the remaining 8% as DOC (<0.2 μm). Large variations in these percentages were recorded. The measured annual primary production was 93 g C m-2 (March to December), and the estimated bacterial production due to phytoplankton exudates 29 g C m-2. This represents a release of DOC of about 45% of the corrected annual primary production of 110 g C m-2 (assuming a bacterial growth efficiency of 0.6).
288 citations
TL;DR: It is hypothesized that the “instantaneous” learning of a novel, or highly unfamiliar, task such as the compensatory articulation of fixed-mandible vowels is possible neither because speakers draw extensively upon past similar experience nor because special motor mechanisms distinct from those of natural speech are invoked.
229 citations
TL;DR: It is demonstrated that the binding of Con A to purified T cells can in a relatively short time, modify their functional sensitivity to growth factors, even though this binding is not sufficient to stimulate them to proliferate.
Abstract: THE process of T-lymphocyte activation requires the participation of metabolically active non-θ-bearing accessory cells1. As first conclusively shown by Habu and Raff2, this requirement is also true of lectin-dependent triggering. Thus, T-cell activation by mitogenic lectins depends on the presence of la-positive non-T cells3,4. The mere binding of lectins such as concanavalin A (Con A) to the surface membrane of T cells does not trigger the cells to go through the mitotic cycle. This can only be achieved by the activity of growth factors present in conditioned media (CM) from Con A-stimulated cell cultures5. Such growth factors, however, cannot activate normal, resting T cells, although they are competent to maintain activated T cells in exponential growth for indefinite periods of time6. Hence, to be mitogenic a lectin must not only induce the in situ production of T-cell growth factors, but must also render resting T cells sensitive to the mitogenic activity of these growth factors. In this report we demonstrate that the binding of Con A to purified T cells can in a relatively short time, modify their functional sensitivity to growth factors, even though this binding is not sufficient to stimulate them to proliferate.
200 citations
TL;DR: In this paper, the authors investigated the number, biomass and oxygen consumption of tardigrades from a Swedish pine forest soil sample for one year and found that all groups fluctuated rather much over the year with a summer minimum (1.1 ˙ 106 animals m-2) and a winter maximum (6.3 ˘ 106 animalsm-2).
Abstract: Nematodes, rotifers and tardigrades from a Swedish pine forest soil were investigated in a monthly sampling programme lasting for one year. The monthly mean values of number, biomass and oxygen consumption were estimated. All groups fluctuated rather much over the year with a summer minimum (1.1 ˙ 106 animals m-2) and a winter maximum (6.3 ˙ 106 animals m-2) for the nematodes. The reasons for these fluctuations are discussed in relation to fluctuations of water content and temperature of the soil. On an annual basis a carbon budget was calculated which gave the following values for this fauna; consumption 4.3, production 0.6, respiration 0.9 and defecation 2.8 g carbon m-2.
197 citations
TL;DR: The kinetics of enzymic reactions in intact cells, in which strand breaks in DNA are produced and sealed again, and it seems that the action of the polymerase was not a rate-limiting event, but rather an earlier step, it is likely that the endonucleolytic activity determined the rate of repair.
Abstract: A simple and sensitive technique for detection of strand breaks in DNA has been further developed. The method has been used to follow UV-induced excision-repair in human fibroblasts. It has been possible to study the kinetics of enzymic reactions in intact cells, in which strand breaks in DNA are produced and sealed again. Hydroxyurea, 5-fluorodeoxyuridine and 1-beta-D-arabinofuranosylcytosine, potent inhibitors of DNA synthesis, drastically increased the number of breaks observed during the repair process. This was probably due to a decreased polymerase activity, which will cause the strand breaks formed by endonuclease to remain open longer. The initial rate of strand-break formation did not seem to be influenced by hydroxyurea or araC, and was about 4000 breaks per minute in a diploid genome, at a dose of 20 J/m2. After 5--30 min, depending on the dose of UV, the number of breaks reached a maximum and started to decrease again. Hydroxyurea decreased the rate of polymerization in the sites under repair. However, there was no concomitant reduction of repair-induced incorporation of [3H]thymidine and no reduction of the excision of pyrimidine dimers. It therefore seems that the action of the polymerase was not a rate-limiting event, but rather an earlier step. It is likely that the endonucleolytic activity determined the rate of repair. As a consequence, the endonuclease and polymerase cannot be bound in a permanent complex. Under certain assumptions, the time for repair of a site, i.e. the time from incision to final ligase sealing, can be estimated as between 3 and 10 min. Essentially no breaks were produced in Xeroderma pigmentosum cells belonging to complementation group A, and there was no enhancement by hydroxyurea. Cells from the variant type of Xeroderma pigmentosum behaved like normal cells in this respect.
194 citations
TL;DR: In this paper, the authors examined the proposition that trade in many commodities can be explained by a chain of comparative advantage and showed that trade accords with the ranking of goods by factor intensity if there are unequal factor prices, free trade, and only final goods.
179 citations
TL;DR: In this article, a model of stable periodic solutions to a simple nonlinear model of the ocean-atmosphere-ice system is presented, which consists of a coupled set of nonlinear ordinary differential equations.
Abstract: A study of stable periodic solutions to a simple nonlinear model of the ocean-atmosphere-ice system is presented. The model has two dependent variables: ocean-atmosphere temperature and latitudinal extent of the ice cover. No explicit dependence on latitude is considered in the model. Hence all variables depend only on time and the model consists of a coupled set of nonlinear ordinary differential equations. The globally averaged ocean-atmosphere temperature in the model is governed by the radiation balance. The reflectivity to incoming solar radiation, i.e., the planetary albedo, includes separate contributions from sea ice and from continental ice sheets. The major physical mechanisms active in the model are (1) albedo-temperature feedback, (2) continental ice-sheet dynamics and (3) precipitation-rate variations. The model has three-equilibrium solutions, two of which are linearly unstable, while one is linearly stable. For some choices of parameters, the stability picture changes and sustained, finite-amplitude oscillations obtain around the previously stable equilibrium solution. The physical interpretation of these oscillations points to the possibility of internal mechanisms playing a role in glaciation cycles.
TL;DR: It is suggested that rat liver microsomes contain glutathione S-transferase distinct from those found in the cytoplasmic and that the microsomal transferase can be activated by modification of microsome sulfhydryl group(s).
TL;DR: The history of the recording and interpretation of the Fennoscandian uplift illustrates the main history of Earth sciences because the results obtained had (and still have) immediate impact of the interpretation of a large number of fundamental problems in Earth sciences as discussed by the authors.
Abstract: The history of the recording and interpretation of the Fennoscandian uplift illustrates the main history of Earth sciences because the results obtained had (and still have) immediate impact of the interpretation of a large number of fundamental problems in Earth sciences. Thanks to a paper of De Geer in 1888, the glacial isostatic origin was established. Fennoscandia became the classic area of glacial isostasy, and its sea level records were used for geophysical calculations of the properties and dynamics of the mantle and crust. The varve dated sea level curve of Liden (1938) from the center of uplift provided an exceptionally well dated record. With the radiocarbon method, the records of shorelines and shorelevel displacement curves were drastically improved providing a totally new basis for the understanding of the geodynamics of the Fennoscandian uplift and for the geophysical interpretation of the data obtained. This is especially true in combination with the repeated levelling data obtained during the last decades for Finland and Sweden.
TL;DR: In this article, a cross-section method was used to study the developmental changes in elementary decoding and encoding processes of 163 Swedish-German bilingual students, whose length of residence in Sweden varied.
TL;DR: Conditioned media obtained from concanavalin A‐stimulated spleen cell cultures maintain mitogen‐derived T cell blasts in exponential growth for indefinite periods of time, but the appearance of activity in CM is Con A dose‐dependent.
Abstract: Conditioned media (CM) obtained from concanavalin A (Con A)-stimulated spleen cell cultures maintain mitogen-derived T cell blasts in exponential growth for indefinite periods of time. Such purified T cell blasts do not respond to Con A, and the growth-promoting activity in CM is independent of the mitogenic lectin used for its production. However, the appearance of activity in CM is Con A dose-dependent. Furthermore, the production of these T cell growth factors is independent of B cells, while it requires both T cells and nontheta-bearing, probably la-positive cells present in normal and nude spleens. On the other hand, the T cell blasts which are reactive to the growth factors, neither produce CM by themselves nor can they cooperate with nude spleen cells for its production, in the presence of a mitogenic lectin.
Since the concentration of growth factors in CM determines the extent of T cell growth, we propose that the growth of some T cells is necessarily dependent upon the activity in CM described here and, consequently, that the basis for T cell activation is the induction of such growth factors.
TL;DR: Growth factors contained in Con A‐CM maintain exponential growth in T cell blasts derived from mitogen stimulation of spleen cells with Con A, phytohemagglutinin, lentil lectin and pokeweed mitogen (PWM), as well as from mixed lymphocyte reactions to H‐2 D or I‐E and I‐C‐encoded determinants and from non‐H‐2 Mls locus‐controlled reactions.
Abstract: Growth factors contained in Con A(concanavalin A)-conditioned media (CM) maintain exponential growth in T cell blasts derived from mitogen stimulation of spleen cells with Con A, phytohemagglutinin, lentil lectin and pokeweed mitogen (PWM), as well as from mixed lymphocyte reactions to H-2 D or I-E and I-C-encoded determinants and from non-H-2 Mls locus-controlled reactions. Such growth factors are strictly T cell blast-specific, inasmuch as they do not stimulate resting, small T or B lymphocytes nor B cell blasts generated by lipopolysaccharide or lipoprotein activation. The responsiveness of T cell blasts to CM appears to be the result of the availability on the cell surface of an acceptor site for growth factors which is not expressed in resting cells, because T cell blasts, but not small spleen cells, absorb out the growth-promoting activity contained in CM. Furthermore, lectins such as Con A and PWM interfere with the blast surface membrane in such a way that they inhibit the response to growth factors. Finally, there is no detectable allotypic or isotypic restriction in the activity of Con A-CM on a variety of target T cell blasts.
TL;DR: 14 cases of sperm tails from men who have spermatozoa that are immotile but living are described, which belong to five distinct groups and three men from this fifth category did not suffer from the immotiles-cilia syndrome.
TL;DR: Treatment of the N-deacylated polysaccharide with nitrous acid caused deamination with concomitant rearrangements, typical of 4-amino-4-deoxyhexopyranosyl residues in which the amino group occupies an equatorial position.
01 Jan 1979
TL;DR: In this paper, the notions of meaning and proof and how they depend on each other are discussed and the question of the completeness of the usual sentential operations is dealt with.
Abstract: In this lecture I shall discuss the notions of meaning and proof and how they depend on each other. In conclusion, I shall deal with the question of the completeness of the usual sentential operations.
TL;DR: In this article, simultaneous measurements of the nightglow profiles of the O2(b1g+−X3Σg−) A-band, the atomic oxygen green line and the OH (8−3) Meinel band are presented.
TL;DR: “iminium oxidase” seems to be a more adequate name for this enzyme, which has a strong affinity for 2a, as shown in a study on the inhibition of the oxidation of 3-(aminocarbonyl)-1-methylpyridinium chloride.
TL;DR: In this article, the fixed point theory of partially ordered sets cannot be reduced to topological fixed point theories, and a substantial number of previously known results in this field are not only subsumed under their approach but are also extended and refined.
TL;DR: The most common substances were trans-nonachlor and oxychlordane, but differences could be observed between species as discussed by the authors, and the probable explanation for their presence in a Swedish lake is air transportation.
TL;DR: The Kattegat sea-level spectrum offers a "eustatic test area" as mentioned in this paper, and the eustatic curve calculated from this spectrum agrees in such detail with the records from other parts of northwestern Europe (e.g., northwest England, The Netherlands, northern Norway).
TL;DR: One of the biphenyls previously known to accumulate in the bronchi was found not to occur in the lung as methylsulfonyl derivatives, but most probably only as the unchanged compound.
TL;DR: In this paper, the authors extended their earlier results on the dollar DM exchange rate to the 1977-78 period and showed that the rise of the DM in the second half of 1978 was consistent with the 'fundamentals' equation.
TL;DR: With adequate safety measures and a well-trained staff, exercise stress testing can be regarded as a safe method to be used in the evaluation of even very ill patients.
TL;DR: In this paper, the stereoisomeric pairs of pyruvic acid and related acetals linked to the 3,4- and 4,6-positions, respectively, of the anomeric methyl d -galactopyranosides and the corresponding acyclic CH3 groups were determined.