Showing papers by "Stockholm University published in 1969"
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TL;DR: It is reported that both mono and dimethylmercury can be produced in bottom sediments and in rotten fish, and relate the findings to the hazards of mercury pollution.
Abstract: FRESHWATER fish, especially pike (Esox lucius), from Sweden sometimes contain abnormally large amounts of mercury1. It was initially concluded to be either inorganic mercury or phenyl mercury, which are known to be released as industrial wastes, but later it was shown that the mercury was present almost entirely as methyl mercury (CH3Hg+)2. A possible explanation is that living organisms have the capacity to methylate mercury compounds present in pollution. We now report that both mono and dimethylmercury (CH3Hg+ and CH3HgCH3) can be produced in bottom sediments and in rotten fish, and relate the findings to the hazards of mercury pollution.
865 citations
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TL;DR: The study of the various pathways by which lymphoid cells can become cytotoxic has been helpful for the understanding of effector role of these cells in cell-destructive reactions in general.
Abstract: Publisher Summary This chapter discusses the cytotoxic effects of lymphoid cells in vitro. The chapter discusses the complex problem of different types of cytotoxic effects of lymphoid cells. These outstanding workers in the field have managed to present a cohesive picture of the various effects on the target cells. The role of “nonspecific” factors is particularly well clarified. The interrelationships among contact lysis, release of pharmacologically active substances, and the terminal components of the complement system are given in the chapter for special consideration. In an in vitro model, it is shown that lymphoid cells from sensitized donors destroy tissue culture cells carrying the antigen to which the cell donor is sensitized. This type of cytolytic reactions is encountered in a great variety of immune situations, comprising all those mentioned in the chapter. The cell that initiates in vitro cytotoxic reaction is assumed to be the sensitized lymphocyte, equipped with its own recognition sites for antigen on the cells that are destroyed. Although this may be true in many situations, it now seems clear that “normal” lymphoid cells can become cytotoxic to other cells by a variety of pathways. The study of the various pathways by which lymphoid cells can become cytotoxic has been helpful for the understanding of effector role of these cells in cell-destructive reactions in general.
581 citations
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TL;DR: In this article, the authors proved the inclusion of subsets Hv of Fv even if the operators P and L are restricted to operate in F. This will follow from their theorem.
229 citations
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TL;DR: In this paper, the time-dependent motion of a rotating stratified fluid is analyzed within the quasigeostrophic approximation, and it is found that the motion is characterized by the ratio B of the stability frequency and the Coriolis parameter.
Abstract: Time-dependent motion of a rotating stratified fluid is analyzed within the quasigeostrophic approximation. A few examples of mechanically driven flow are analyzed. It is found that the motion is characterized by the ratio B of the stability frequency and the Coriolis parameter. Thus the ratio of the horizontal and vertical characteristic scale is in general O(B). In particular the decay process caused by a horizontal boundary will penetrate a distance B−1L into the fluid, L denoting the horizontal scale of the motion.
121 citations
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TL;DR: The findings fit the working hypothesis tested, which regards salt tolerance as partly dependent on the ability to mobilize energy to extrude Na from the cells and to take up K, and the total salt level of the cells is not sufficient to counteract the osmotic potential of the medium.
Abstract: By using the isotope pairs 22Na-24Na and 42K-86Rb, the uptake and retention of Na and K was studied in the salt-tolerant Debaryomyces hansenii and in the less tolerant Saccharomyces cerevisiae at NaCl levels of 4 mm and 0.68, 1.35, and 2.7 m in the medium. The ratio of K to Na is much higher in the cells than in the media, and higher in D. hansenii than in S. cerevisiae under comparable conditions. The difference between the two species is due to a better Na extrusion and a better uptake of K in D. hansenii. The kinetics of ion transport show that at about the time when extrusion of Na could be demonstrated in D. hansenii, K-Rb previously lost to an easily washable compartment of the cells was reabsorbed in both organisms. More H+ was given off from S. cerevisiae than from D. hansenii in the course of these events. The findings fit the working hypothesis tested, which regards salt tolerance as partly dependent on the ability to mobilize energy to extrude Na from the cells and to take up K. The volume changes in S. cerevisiae are greater and are more slowly overcome than those in D. hansenii. The total salt level of the cells is not sufficient to counteract the osmotic potential of the medium, so that additional osmoregulatory mechanisms must be involved in determining halotolerance.
116 citations
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83 citations
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TL;DR: It is pointed out in this paper that a high cross-contamination occurs when fractionation is performed with these Spinco rotors, however, good separation with a high yield can be obtained with the Spinco centrifuge if the 40.2 rotor and the procedure that is described are employed.
81 citations
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TL;DR: It is interpreted that the observed differences between Vicia and Nigella are due to the presence and absence of heterochromatin in their chromosome complements respectively.
Abstract: The chromosome breaking effect of mitomycin C, methyl methanesulfonate, maleic hydrazide, 8-ethoxycaffeine and gamma rays on the primary root meristematic cells of Nigella damascena was studied. All the agents tested except 8-ethoxycaffeine, produced relatively fewer aberrations, when compared to Vicia faba cells, though both the species have nearly similar total chromosomal length. Test for the presence of heterochromatin in Nigella gave negative results and it is interpreted that the observed differences between Vicia and Nigella are due to the presence and absence of heterochromatin in their chromosome complements respectively. The role of heterochromatin in the production of chromosome aberrations and its significance in evolution are briefly discussed.
78 citations
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TL;DR: The results support the hypothesis that in contrast to phenobarbital, 3,4-benzpyrene yields a modified cytochrome (P-448) in the liver microsomes with an increased affinity for 3, 4-benZpyrene as well as a decreased affinity for aminopyrine.
77 citations
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TL;DR: In this paper, the problem is to estimate φ(m) 1/m, λ(m, λ 1/ m, ν(m), ν 2/m as m → ∞, where m is the set of all vectors of dimension m with all components 0 or 1.
74 citations
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TL;DR: The results suggest a nonrandom distribution of these two enzyme groups in the membranes of the endoplasmic reticulum, NADH-ferricyanide reductase and cytochrome b5 are most concentrated within the large vesicles in the lowest third of the gradient, while NADPH-cytochrome c reductases and cy tochrome P-450 are found in highest concentration in the small vesicle that make up the upper third ofThe gradient.
Abstract: Microsomal membranes are postulated to contain either a homogeneous arrangement of individual enzymes or groupings of functionally related enzymes. In the present study we attempt to distinguish between these hypotheses in subfractions of rough microsomes from rat liver. After sonication, the individual vesicles that make up the rough-membrane fraction average less than 1/100 of their previous mass. The vesicles in the sonicated suspension are fractionated roughly according to size on a continuous sucrose gradient. Enzyme activity or concentration in fractions of the gradient is expressed on a phospholipid basis. Fractions containing primarily small vesicles differ from those containing larger vesicles in a manner suggesting a certain degree of separation of NADH-linked from NADPH-linked enzymes. NADH-ferricyanide reductase, NADH-cytochrome c reductase and cytochrome b5 are most concentrated within the large vesicles in the lowest third of the gradient. In contrast, NADPH-cytochrome c reductase and cytochrome P-450 are found in highest concentration in the small vesicles that make up the upper third of the gradient. The results suggest a nonrandom distribution of these two enzyme groups in the membranes of the endoplasmic reticulum.
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TL;DR: A metabolic link between an energy-rich intermediate of the electron transport coupled energy transfer pathway is postulated to exist and a scheme for the suggested connections between energy sources, chlorophyll, and cytochromes in relation to carotenoid is given.
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TL;DR: Chromium-51-labeled chicken erythrocytes treated with rabbit anti-Forssman antibody and the first four or the first seven components of human complement, released isotope upon exposure to human leukocytes, which affected both types of target cell-complement intermediates.
Abstract: Chromium-51-labeled chicken erythrocytes (E), treated with rabbit anti-Forssman antibody (A) and the first four (C1-4) or the first seven (C1-7) components of human complement (C), released isotope upon exposure to human leukocytes. Isotope release from EACJ-7 cells proceeded more rapidly and was more extensive than that from EACI-3 cells. Lysis of these cells was suppressed by pretreatment of leukocytes with antimycinA. Monocyte-enriched leukocyte preparations affected both types of target cell-complement intermediates, whereas purified lymphocytes lysed EACI-7 cells but not EACI-3 cells.
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TL;DR: The ability of soluble succinate dehydrogenase to reconstitute the succinate oxidase system is irreversibly lost after pretreatment with oxaloacetate and it is suggested that oxalo acetate may either bind rather tightly with the enzyme or promote a reversible conformation change leading from the active form of the dehydrogen enzyme to an inactive one.
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TL;DR: It is indicated that alkylation of protein SH plays a predominant role in cell killing, and iPMS which has the lowest s of the investigated compounds seems to kill cells mainly by a genetic mechanism, giving a nearly one-hit exponential survival curve.
Abstract: The bactericidal and mutagenic effectiveness in E. coli of a few unsubstituted and substituted methanesulfonic esters and diethyl sulfate was related to the substrate constants, s , of the alkylating agents. The relative LD 50 values of the compounds except isopropyl methanesulfonate (iPMS) were found to agree with the relative reaction rates at a nucleophilic constant n = 5.1–5.5; it is, hence, indicated that alkylation of protein SH plays a predominant role in cell killing. iPMS which has the lowest s of the investigated compounds seems to kill cells mainly by a genetic mechanism. In contrast to the sigmoid survival-dose curves obtained with the other substances, iPMS gives a nearly one-hit exponential survival curve. iPMS was also demonstrated to differ from the other compounds by the absence of after-effects in treated cells, such as the enhanced killing during a post-treatment incubation in the absence of Mg 2+ . The relative mutagenic effectiveness (mutation to streptomycin independence in the strain Sd- 4 ) of the compounds studied, including iPMS, agrees with relative alkylation rates at n = ca . 2,5, i . e . close to values found for DNA. Also with respect to mutation iPMS differs from other compounds, giving a practically linear dose-response curve. Ethyl methanesulfonate (EMS) and other compounds with intermidiate s values give, superimposed on a linear component distinguishable at low doses, exponential (“multi-hit”) mutation curves leading to high mutation frequencies around LD 50 .
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TL;DR: There was an inhibition of the NADPH-linked drug hydroxylation and lipid peroxidation activities, as well as an inactivation of the reduction of cytochrome b5 by NADPH, while the NADH-cytochrome c reductase system was considerably less sensitive to trypsin treatment of the microsomes.
Abstract: Treatment of rat liver microsomes with low amounts of trypsin resulted in an inactivation of NADPH-cytochrome P-450 reductase parallel to the release of NADPH-cytochrome c reductase. Associated herewith there was an inhibition of the NADPH-linked drug hydroxylation and lipid peroxidation activities, as well as an inactivation of the reduction of cytochrome b5 by NADPH. The NADH-cytochrome c reductase system, on the other hand, was considerably less sensitive to trypsin treatment of the microsomes. The inhibition of the NADH-cytochrome c reductase activity at higher concentrations of trypsin was, however, likewise correlated with a solubilization of cytochrome b5. High concentrations of trypsin also caused a conversion of cytochrome P-450 into cytochrome P-420 and a disappearance of the spectral shift characteristic of the interaction of cytochrome P-450 with substrates of the hydroxylating system.
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TL;DR: In this paper, an oxygen-deficient hexagonal phase in oxygen at 850°C for 2 h produces stoichiometric samples which are still hexagonal, whereas the tetragonal/cubic structure is restored by heating for 1 h at 1350°C.
Abstract: Reducing high-purity BaTiO3 in hydrogen for 1 h at 1275°C leads to an oxygen deficiency x= 0.0036 in BaTiO3–x with maintenance of the tetragonal/cubic perovskite-type structure. Reduction at 1325° C leads to x= 0.0073 and brings about transformation to the hexagonal modification. Up to 1500°C (x= 0.0233) no further phase change occurs. Annealing the oxygen-deficient hexagonal phase in oxygen at 850° C for 2 h produces stoichiometric samples which are still hexagonal, whereas the tetragonal/cubic structure is restored by heating for 1 h at 1350°C. The unit cell found for the hexagonal phase is somewhat smaller than previously reported.
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TL;DR: The content of acid ether-soluble auxins and inhibitors in vegetative tissues of aspen (Populus tremula L.) was determined with the Avena coleoptile straightgrowth assay and a growth promotor, tentativety identified as indol-3-yl-acetic acid, occurred in highest concentration in the growing stem parts.
Abstract: The content of acid ether-soluble auxins and inhibitors in vegetative tissues of aspen (Populus tremula L.) was determined with the Avena coleoptile straightgrowth assay. A growth promotor, tentativety identified as indol-3-yl-acetic acid, occurred in highest concentration in the growing stem parts. It was also detected in various parts of the roots. Large amounts of inhibitors (inhihitor β) were found in growing stem tissue and in upper mature stem parts. Considerably lower content of inhibitors was found in leaves, in the basal stem part and in the roots. Nonwoody growing roots and the wood of older root segments, especially, contained very smalt quantities of inhibitors. The elution volume of a part of the inhibitory activity on a Sephadex column was similar to that of abscisic acid.
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TL;DR: ‘Vertical linearity’ and ‘Roundness’ are the most important of these factors and account for a considerable portion of the similarity among many letters.
Abstract: Summary.-28 lower-case letters of the Swedish alphabet were studied by the method of multidimensional similarity analysis. 57 Ss participated in the experiment. 9 factors were found. Factor I is called 't' or 'Vertical linearity,' Factor 11: '0' or 'Roundness,' Factor 111: 'n' or 'Parallel vertical linearity,' Factor IV: 'i' or 'Vertical linearity with dot,' Factor V: 'p' or 'Roundness attached to vertical linearity,' Factor VI: 'k' or 'Vertical linearity with crossness,' Factor VII: 'a' or 'Roundness attached to a hook,' Factor VIII: 'v' or 'Angularity open upward' and Factor IX: '2' or 'Zigzaggedness.' 'Vertical linearity' and 'Roundness' are the most important of these factors and account for a considerable portion of the similarity among many letters. In previous experiments with nine capital letters (Kuennapas, 1966, 1967, 1968a) it was shown that multidimensional similarity analysis (Ekman, 1965, 1968) could be used successfully for the study of the perceived forms of these capitals. The factors revealed by the analyses could be interpreted easily and meaningfully as 'Rectangularity,' 'Roundness' and 'Vertical linearity.' The purposes of the present study were (a) to extend the multidimensional similarity analysis to the whole alphabet of lower-case letters, and (b) to reveal the main perceptual dimensions of visual forms of these letters.
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TL;DR: In this paper, the authors define a vector notation for Borel measures on real Euclidean w-space, where the product of the measures is the convolution a * r and the norm of a measure is its total variation.
Abstract: 1. Notation and definitions. Let R denote real Euclidean w-space. We shall employ standard vector notations, whereby / = (tu • • •, tm), u = («i, • • • , um) denote points of R , tu = ^ ï* /*w» and 11\ = (tt). In connection with Fourier transforms x = (xi, • • •, xm) denotes a point of a "dual" copy of R. M=M(R) shall denote the totality of bounded complex-valued Borel measures on R, made into a Banach algebra in the usual way, i.e. the "product" of the measures and 0 let , a G I f and a > 0 let us define
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TL;DR: The hypothesis was substantiated that perceived size of space depends on perceived depth and judged size (rectangular area) might be a power function of judged depth times perceived width.
Abstract: Garling, T. Studies in visual perception of architectural spaces and rooms. I. Judgment scales of open and closed space. Scand. J. Psychol., 1969, io, 250–256.—Eight observers judged open and closed space, viewing spaces from different spots along a street in a small town. The spaces were viewed and judged either as wholes or parts by using a ratio scaling procedure. The observers were found to make reliable judgments of closed and open space. The function relating these judgment to each other approximated, however, a complementary relation as expected for category ratings. Judgments of whole spaces might be predicted from averaged judgments of their parts.
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TL;DR: Heart rate, systolic pressure, and subjective effort increased consistently with increasing work load, while catecholamine-excretion rates remained close to control levels at the lower work loads, while the highest load induced a significant increase in both adrenaline and noradrenaline output.
Abstract: Catecholamine excretion, cardiovascular functions, and subjective effort were studied in 10 healthy male Ss in a control condition and in three experimental sessions in each of which 5 successive 6...
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TL;DR: Emotional involvement was found to be inversely proportional to the square root of subjective distance, when other variables were kept constant, and the result of a previous study by Ekman and Bratfisch is thus further confirmed.
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TL;DR: The final steps of the reactions leading to the formation of inorganic pyrophosphate (PP i) or ATP in bacterial photophosphorylation have been shown by us to be reversible to the level of electron transport in chromatophores from Rhodospirillum rubrum by addition of either of these two compounds in the dark.
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TL;DR: This type of flavin is mostly, if not exclusively, connected with succinate dehydrogenase flavoprotein from aerobic cells (“SD-flavin”) and differs from acid-extractable flavin of the same tissue by the following main characteristics: pH-dependence of the fluorescence, optical spectra and alkaline photolysis.
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TL;DR: The structure of the lipopolysaccharide from Salmonella friedenau T1 form has been investigated and a low percentage of branching, through β-d-galactofuranose residues, substituted in the 3- and 6-position is demonstrated.
Abstract: The structure of the lipopolysaccharide from Salmonella friedenau T1 form has been investigated. The T1-specific chains are composed of almost equal amounts of β-d-ribofuranose and β-d-galactofuranose residues. The former are linked to the 2-position, the latter to the 3-position or, to a smaller extent, to the 6-position. A low percentage of branching, through β-d-galactofuranose residues, substituted in the 3- and 6-position, is demonstrated. The core region of the T1 lipopolysaccharide seems to have the same general structure as that of other Salmonella lipopolysaccharides.
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TL;DR: A strong matrix ENDOR signal was observed, which decreased by about 40% when 2 H 2 O was used as solvent, which indicates that the active sites are inside the protein and should be correlated to the percent of exchangeable protons in the immediate environment of the active site.
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TL;DR: The fruit bodies of the fungi Polyporus fomentarius and polyporus igniarius have been examined for polysaccharide content as discussed by the authors, and they both contain a mannofucogalactan and a glucuronoglucan.
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TL;DR: The results showed that the apparent duration of the signal grew as a logarithmic function of stimulus intensity, consistent with the hypothesis relating apparent duration to activation level as well as with results of similar experiments involving electrical and vibrotactile stimulation.
Abstract: Berglund, B., Berglund, U., Ekman, G. & Frankenhaeuser, M. The influence of auditory stimulus intensity on apparent duration. Scand J. Psychol., 1969, 1021–26.— apparent duration of an auditory signal of 1000 C/S was measured by the method of magnitude estimation. Ten different stimulus intensities ranging from 57 to 104 dB were used in combination with three different durations: 50, 250, and 500 msec. The results showed that the apparent duration of the signal grew as a logarithmic function of stimulus intensity. These results are consistent with the hypothesis relating apparent duration to activation level as well as with results of similar experiments involving electrical and vibrotactile stimulation.
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TL;DR: Results show that the site of inactivation caused by the extraction of UQ occurs in the region between the NADH and succinate dehydrogenases and cy tochrome b, and that UQ is essential for electron transport between the two flavoproteins and the cytochrome system.