Showing papers by "Stockholm University published in 1968"

Synthesis of methyl-mercury compounds by extracts of a methanogenic bacterium.

Abstract: THERE have been incidences of extensive alkyl-mercury poisoning in Japan and Sweden. In Japan a large number of people belonging to the fishing population around Minamata Bay were seriously affected by what is now called Minamata disease. This incident was traced back to pollution of the bay with the mercury containing effluent of a large chemical plant. When methyl thiomethyl-mercury was isolated from shellfish in the area of the bay it was suggested that mercury could be alkylated by “plankton and other marine life”2. It was discovered later that the spent catalyst of an acetaldehyde reactor, which caused the pollution, contained approximately 1 per cent methyl mercury; and the biological methylation of mercury was thought to be insignificant.

A new method based on the use of diethyl pyrocarbonate as a nuclease inhibitor for the extraction of undegraded nucleic acid from plant tissues.

Abstract: A new method, based on the use of the diethyl pyrocarbonate as a nuclease inhibitor, has been worked out for the extraction of undegraded nucleic acids from etiolated and green plant tissues. Experimental evidence is given to show that the nucleic acids isolated by this method exhibit a high degree of purity as evidence by their spectra and that they are essentially undergraded as indicated by sedimentation patterns in sucrose density gradients.

Ion Transport Induced by Light and Antibiotics in Chromatophores from Rhodospirillum Rubrum

Abstract: 1 On illumination, chromatophores of Rhodospirillum rubrum took up hydrogen ions from the medium. Hydrogen ion uptake was inhibited or reversed by uncoupling agents and by Triton-X114. 2 Addition of valinomycin in the dark to chromatophores suspended in a medium of low KCl concentration gave rise to a loss of potassium ion from the chromatophores, and a slow H+-uptake. Illumination gave rise to a further efflux of potassium ion, and a stimulated H+-uptake. The light-induced potassium ion efflux increased in extent with increasing external KCl concentration. At high KCl concentrations hydrogen ion efflux occurred on addition of valinomycin in the dark, and a greatly stimulated initial rate of H+-uptake on illumination was observed. 3 Addition of gramicidin to chromatophores in the dark gave rise to effects similar to those observed with valinomycin. On illumination, the uptake of hydrogen ion was somewhat inhibited, and rapidly reversed in the dark. 4 Addition of nigericin in the dark to chromatophores suspended in a medium of low KCl concentration gave rise to a rapid efflux of potassium ion, and an uptake of hydrogen ion which was nearly stoichiometric in rate and extent. On illumination an inhibited H+-uptake occurred, together with an uptake of potassium ion from the medium. The inhibition of H+-uptake, and the extent of K+-uptake were dependent on nigericin concentration and KCl concentration. The sum of the extent of K+-uptake and the extent of H+-uptake was approximately the same in all cases, indicating that an exchange of hydrogen ion within the chromatophores for potassium ion in the medium had occurred. 5 Nigericin gave rise to hydrogen ion efflux from chromatophores suspended in media of high KCl concentration when added in the dark or light. The efflux observed in the light was more extensive and represented a reversal of hydrogen ion uptake. The KCl concentration at which nigericin caused no pH change was shifted from about 4 mM in the dark to about 0.4 mM in the light. The pH gradient across the chromatophore membrane was calculated to be approximately 1 pH unit. 6 Valinomycin inhibited nigericin induced K+-uptake in the light. At high KCl concentrations nigericin inhibited H+-uptake in the absence or presence of valinomycin. 7 No marked inhibition of photophosphorylation by nigericin or valinomycin alone was observed even at high KCl concentrations. However, when both antibiotics were present together in the reaction medium, inhibition was observed which was dependent on the KCl concentration. In the absence of added KCl, no inhibition occured but at 10 mM KCl phosphorylation was 86%, and at 100 mM, 93% inhibited. Similar results were obtained when phosphorylation was coupled to electron flow in uninhibited chromatophores, or through N-methyl phenazonium methosulphate in 2-heptyl-4-hydroxy quinoline N-oxide inhibited chromatophores. Similar effects were observed when dianemycin was used instead of nigericin. 8 The mechanism of action of the antibiotics tested is discussed. It is suggested that their mode of action on chromatophore membranes is the same as that shown for artificial membrane systems. In particular, it is proposed that nigericin and dianemycin are able to catalyse a cation/cation or cation/hydrogen ion exchange across lipid barriers, which is closely coupled and electrically neutral.

Immunological studies in ulcerative colitis. IV. Origin of autoantibodies.

Abstract: The incidence and height of antibody titers to colon, assayed by indirect hemagglutination with a heat stable colon extract from germ free rats, is significantly higher in sera from patients with ulcerative colitis than in those from healthy controls or from patients with amebic liver abscess or dysentery. While sera from ulcerative colitis patients and controls are indistinguishable in regard to incidence and height of antibody titers to Forsman antigen, Staphylococcus aureus S 209, Clostridium difficile, and several common strains of E. coli, they have elevated titers and increased incidence of antibodies to a heat stable antigen of E. coli O14. Patients with amebic dysentery have normal titers of such antibodies. Absorption of patients' sera with E. coli O14 antigen inhibits the colon directed hemagglutination reaction in approximately 30% of the cases tested. Likewise, the anti-E. coli O14 reaction can sometimes be inhibited with the colon extract. Other E. coli strains and other bacteria are inactive or have only weak inhibitory activity. Hemagglutination inhibition experiments show that germ free rat colon and E. coli O14 contain common structures, depicted by antibodies in the patients' sera. This pattern of reactivity closely resembles that seen in rats made autoimmune to colon by injection of newborn rabbit colon. E. coli O14 is known to carry a heterogenetic antigen present in lower concentration (or activity) in most Enterobacteriaceae. Hemagglutination inhibition experiments with rabbit antisera to E. coli O14 suggest that the antigen common for E. coli O14 and colon is related to this heterogenetic antigen. The findings imply that this antigen, which is constantly present in low concentrations in the human colon, may give rise to anticolon antibody formation in ulcerative colitis through breakage of tolerance. Since this antigen is present in healthy individuals as well, additional factors are required to explain the induction of anti-colon autoimmunity in ulcerative colitis.

A simple test for uniformity of a circular distribution

Abstract: SUMMARY Consider a finite set of points, located on the circumference of a circle. Several tests have been proposed of the hypothesis that the points constitute a random sample from a uniform distribution. In this paper we study a test statistic defined as the maximal number of points that can be covered by some semicircle. Exact and asymptotic distributions under the null hypothesis, and under a certain alternative hypothesis, are given together with some tables. A related test statistic is studied briefly. An expression is obtained concerning most powerful invariant tests of the hypothesis of a uniform circular distribution. In 1965, Dr G. Borenius described an unpublished experiment with a bubble chamber, where points representing events were observed through a circular window. A natural hypothesis was that the events occurred at random with a constant probability density within the circle. In one case it was observed that 67 out of 100 events fell within a suitably chosen semicircle. The question then arose whether this asymmetry should be judged inconsistent with the hypothesis of a uniform distribution. More generally, suppose that n points are observed and that each point is moved radially to the circumferences of the circle. We then have a sample of n points on the circumference and want to test the hypothesis that the underlying probability distribution is uniform over the circumference. The test statistic suggested by the foregoing paragraph is the maximal number of points in the sample that can be covered by a suitably chosen semicircle. In the following this test statistic will be denoted by N. We reject the hypothesis if N is too large. Many other tests of the same hypothesis have been proposed. For example, the classical Kolmogorov-Smirnov test has been adapted to circular distributions by Kuiper; see Kuiper (1960) and Stephens (1965). Watson (1961) did the same thing for the Crame6r-von Mises test. A detailed study of the null distribution of Watson's test statistic has been made by Stephens (1963, 1964). For a general review of statistical methods in connexion with circular distributions, see Batschelet (1965). The problem of determining the distribution of N under the hypothesis is purely combinatorial. It was solved by Borenius for sample sizes n up to n = 15 and the general solution was inductively conjectured by him. He thus found that the above-mentioned observation, N = 67 for a sample of size n = 100, corresponds to a level of significance P = 1U6 0/. Dr S. Johansen, University of Copenhagen, has told the author that he, too, has found the null-distribution of N. This was done in connexion with an application to the study of

Quantitative and experimental studies of the interstitial fauna in four Swedish sandy beaches

Abstract: The distribution of the interstitial metazoans was studied quantitatively in four Swedish beaches, three in the Baltic and one in the Skagerrak. As many as 1.5 × 106 individuals per m2 were found (Asko beach, south of Stockholm). Temperature, salinity, oxygen concentration and availability, grain size, water contents and organic material were measured in connection with the sampling. The oligochaetes, turbellarians and harpacticoids showed different degrees of submergence landwards in the beaches with the oligochaetes near the sand surface, followed by the turbellarians and - deepest down - the harpacticoids. This may be explained by a difference in dependence on water-saturation: the oligochaetes are more or less terrestrial, and the turbellarians can move in a thinner water film than can the harpacticoids. A correlation between the distribution of oxygen and certain species was found in several cases. The microbial film on the sand grains is pointed out as an important food-source and the utili...

A Survey of Some Connections Between Classical, Intuitionistic and Minimal Logic

Abstract: Publisher Summary This chapter discusses the relationships among classical, intuitionistic and minimal logic. Classical logic is interpretable (also interpretable with respect to derivability) in intuitionistic and minimal logic by the translation absurdity, conjunctions, implications, and universal formulas. If the intuitionistic natural number theory is consistent, then the classical natural number theory is also consistent. Intuitionistic predicate logic is interpretable (also interpretable with respect to derivability) in classical predicate logic. A classical argument can be understood intuitionistically, if the formulas are interpreted throughout in the weak sense, that is, classical logic can be interpreted in intuitionistic logic by a translation that successively replaces classical formulas by their double negation. The chapter suggests that the axioms for classical and intuitionistic natural number theory are the same.

On the new “psychophysical law”: A validation study

Abstract: Controversies on Stevens’ “new psychophysics” were first reviewed brieny and classified. Then, the validity of subjective ratio scales, including the validity of the psychophysical power law were studied both theoretically and experimentally: (1) It was argued that the results of the method of cross-modality matching (CMM) should in general disagree with those from the direct estimation methods due to the variation of the exponent with various factors; (2) An experimental situation was arranged where 20 Os took part in both CMM and the magnitude estimation experiments in order to make the two sets of results comparable; (3) As expected, the results pointed to the invalidity of the subjective ratio scales and the power law rather than their validity, since the equal-sensation functions predicted from CMM disagreed with those obtained from magnitude estimation on three criteria, namely, slope, linearity and curvilinearity, presence and absence of an additive constant.

Cytotoxic Action of Stimulated Lymphocytes on Allogenic and Autologous Erythrocytes

Abstract: Fowl erythrocytes are lysed when exposed to an excess of fowl blood lymphocytes in the presence of phytohemagglutinin. No significant cell damage is seen in the absence of phytohemagglutinin, or when the lymphocytes are replaced by malignant lymphoid cells, thymus cells, or nonlymphoid cells. The lymphocytes remain viable during the reaction. Differences in histocompatibility between lymphocytes and erythrocytes are not required. Autologous lymphocytes are cytotoxic to the same extent as allogenic lymphocytes over a wide range of experimental conditions.

Interindividual differences in scaling performance.

Abstract: 21 Ss performed complete ratio estimation of 7 stimuli in each of 6 continua. Individual scales were constructed and condensed into a measure of scale range. The coefficients of correlation between continua were positive and mostly statistically significant but much lower than the coefficients of reliability. The results support a two-factor hypothesis, according to which individual differences in scaling behavior reflect both a genuine perceptual variability and differences in response bias.

Dosage and time effects of cigarette smoking.

Abstract: Effects of cigarette smoking were examined in eight healthy habitual smokers. Comparisons between effects on catecholamine excretion produced by 2, 4, and 6 cigarettes, smoked within a 2-hr period, showed a progressive increase in adrenaline excretion with number of cigarettes, while noradrenaline excretion was not noticeably affected. Comparisons between smoking and control conditions showed effects on hand steadiness, skin temperature, heart rate, and blood pressure. Dose- and time-response curves indicated that the relatively largest effect was regularly produced by the first cigarette, while the 2nd to 6th cigarette produced progressively smaller changes.

The simultaneous use of chemical tracers in oceanic studies II. A three‐reservoir model of the North and South Pacific Oceans

Abstract: Salinity, oxygen, inorganic phosphorus, organic and inorganic carbon, carbonate alkalinity, insoluble carbonate, and radiocarbon are used simultaneously as tracers to investigate oceanic circulation, chemical processes within the ocean and chemical exchange at oceanic boundaries. Estimates of the rates of these processes are made using the equation for chemical transport in the simplest approximation which recognizes spatially variable exchange at the ocean-atmosphere boundary, horizontal and vertical advective and eddy diffusive transport, and gravitational settling of insoluble chemicals within the oceans. This approximation is a cyclic model with one atmospheric and three oceanic reservoirs between which tracers exchange by first-order kinetics. Data for the Pacific Ocean are used after having been averaged over time and the regions: warm surface water, cold surface water, and deep water. Northern and southern cold surface waters are treated as alternate cases. We deduce that: 1 The mass of deep water in the Pacific Ocean divided by its rate of production is about 1100 years, a time interval in close agreement with its average radiocarbon age relative to that of cold surface water. 2 In the South Pacific Ocean, the transfer of water between the deep ocean and the surface is principally by exchange with cold surface water. A small net circulation from warm surface water to cold surface water is suggested by the model, but the rate cannot be calculated with existing information. 3 The three-reservoir model cannot, even to a first approximation, explain the circulation of the North Pacific Ocean, because it overlooks the flow of deep water into the North Pacific Ocean from the South Pacific Ocean. 4 Both oxygen and carbon dioxide are evolved from surface waters at low latitudes and absorbed at high latitudes. The rates of exchange from warm surface water to cold surface water are of the order of 10 17 mmol yr ?1 . 5 About 10% of the inorganic carbon in deep water arrives there from surface water by gravitational settling of organic carbon and insoluble carbonate. The other 90% is transported there by the water itself. 6 The use of pH measurements to assay for dissolved inorganic carbon and alkalinity seriously limits the reliability of carbon data in the present study. Small errors in pH result in large uncertainties in the deduced rates of gravitational transport of organic carbon and insoluble carbonates and in the rate of exchange of CO 2 with the atmosphere. DOI: 10.1111/j.2153-3490.1968.tb00348.x

Electron microscopic studies of unfertilized and fertilized eggs from marine teleosts

Abstract: Ripe eggs of several species of marine teleostean fishes were studied in the unfertilized state and after insemination. The ultrastructure of the fish egg was investigated and several species-specific differences were discovered in the surface layers of the ripe egg. The electron microscopic changes found upon fertilization of the egg are discussed.

Optical characteristics of mesospheric aerosol distributions in relation to noctilucent clouds

Abstract: It has not hitherto been possible to establish whether the appearance of noctilucent clouds is due to an increased concentration or locally increased size of solid particles at the mesopause, or to a combination of these mechanisms. In this contribution the possibility of a relationship between the optical characteristics of noctilucent clouds and ice sublimation is discussed on the basis of present-day knowledge of the structure and photochemistry of the mesosphere. The first part is devoted to a discussion of the character of the sublimation process at these altitudes. It is found that such a process is possible in conditions prevailing at the high-latitude summer mesopause. The time scale of sublimation and evaporation is slow compared with horizontal translation velocities observed in this region. Below the mesopause evaporation becomes rapid compared with the settling speed of submicron particles. In the second part the scattering properties of monodisperse and polydisperse particle distributions, and the possible changes following a sublimation process are reviewed on the basis of numerical computations of scattering functions of coated spherical particles. It is found that the optical consequences of sublimation depend critically upon the presence and relative concentration of particles obeying the Rayleigh scattering law in the visible spectrum. The characteristic time scale of brightness changes by sublimation is at least 10 to 100 minutes. Different optical methods for further investigation of the nature of mesospheric aerosols are summarized and a method is proposed for the detection of scattering layers in the mesosphere by means of ultraviolet intensity and polarization measurements from rockets and satellites. DOI: 10.1111/j.2153-3490.1968.tb00354.x

Porteus Maze Differences Between Psychopathic and Non‐psychopathic Criminals

Abstract: Rule-breaking, careless drawing and some other behaviours observed in the Porteus Maze test have been shown to differentiate between delinquent and non-delinquent groups. In this study it was assumed that the frequencies of errors would be related to a classification along the dimension of psychopathy as defined by Cleckley (1955). Criminals were rated by psychiatrists for degrees of psychopathy. As expected, Ss with high ratings in psychopathy committed significantly more errors. The relationships between the error scores (Q-scores) and some other variables are reported. Some modifications in the scoring are suggested.

The Role of Cytochrome P-450 in Microsomal Mixed Function Oxidation Reactions

Abstract: The central role of oxygen in many metabolic reactions of the cell is the general theme of this colloquium. Prof. Lubbers [1] has described the role of the hemoproteins, hemoglobin and myoglobin in oxygen transfer reactions whereas Prof. Chance [2] has presented his elegant experiments on the reduction of oxygen by the mitochondrial respiratory chain. The present discussion will center on a different type of reaction in which oxygen participates in many mammalian cells. These reactions are those which have been termed [3] mixed function oxidation reactions — reactions which are catalyzed [4] by a unique hemoprotein called cytochrome P-450.

Grímsey and the Maximum Extent of the Last Glaciation of Iceland

Abstract: It was formerly supposed that the small island of Grimsey about 40 km north of the mainland of Iceland, had not been glacierized during the Wurm period. Evidence for a glaciation is presented toget...

Cu2+ in Non Axial‐Field: A Model for Cu2+ in Copper Enzymes

Abstract: By γ-irradiation at 77° K of the Cu1+-containing organic crystals, Cu(CH3CN)4ClO4, Cu(HOOCCH2CH2CN)4ClO4, and Cu(CH3CN)4BF4, Cu2+ centres in near-tetrahedral field were produced. These Cu2+ centres approximated the electron spin resonance characteristics (|A1|= 0.008 cm−1) and light absorption of Cu2+ in Cu-containing oxidoreductases. No exact correlation was found between the g-values of the model system and the Cu-oxidases. It is suggested that the Cu site in these enzymes is intermediate between the square planar (normal for Cu2+) and the tetrahedral (normal for Cu1+) configuration, which makes it suited for rapid electron transport.