Showing papers by "University of Aberdeen published in 1974"

The relationship between plasma and tissue lipids in human atherosclerosis.

Abstract: Publisher Summary This chapter discusses the relationship between plasma and tissue lipids in human atherosclerosis. The concentration of lipoprotein in normal intima is highly correlated with plasma lipoprotein level. The amount and composition of lipid differs greatly between intima and media, and between normal intima and the different types of lesion. In normal intima, there is a progressive increase in the concentration of most lipid classes with age and morphologically this is correlated with increasing numbers of perifibrous lipid droplets that are particularly associated with fragmentary elastic laminae in the deeper layers. With increasing amounts of amorphous atheroma lipid in the deep layers of the lesion, there is a marked increase in the proportion of free cholesterol, decrease in proportion of ester cholesterol, and change in the cholesterol ester fatty acid pattern. Because of the high correlation between intimal and plasma lipoprotein levels, the effect of age can only be examined in terms of volumes of the patient's plasma in the intima.

The ground-state average and equilibrium structures of formaldehyde and ethylene

Abstract: The use of recently determined highly precise rotational constants for various isotopes of formaldehyde and ethylene enables the ground-state average structures to be determined to high accuracy. Harmonic corrections to the inertial constants are calculated using recently determined general harmonic force fields. In the case of formaldehyde, the data enable changes in all three structural parameters due to isotopic mass effects to be determined. For ethylene, only the change in CH bond length on deuteration is well characterized, due to the somewhat lower accuracy in the rotational constants. Using isotopic structural differences transferred from formaldehyde, and supported by calculations, ground-state rotational constants for all deutero isotopes of ethylene are predicted to what is considered to be better than 0·1 per cent reliability. The change in CH bond length on deuteration in ethylene is less than in formaldehyde. This is supported by calculations, although it appears also that the CH bond stretc...

A study of potassium gradients in the epidermis of intact leaves of Commelina communis L. in relation to stomatal opening

Abstract: Potassium sensitive microelectrodes have been used to determine the potassium content of individual epidermal cells in intact leaves of C. communis L. Large gradients of potassium across the stomatal complex were observed. When the stomata were open a stepwise decrease in vacuolar potassium content from the guard cells outwards was found. With the stomata closed a gradient in the opposite direction was observed, with the potassium content of the guard cells much lower than that of the surrounding cells. Electrical potential differences between the cells were determined enabling driving forces on potassium to be calculated. The results indicate that the potassium gradients are maintained against the electrochemical gradient and that potassium transport both into and out of the guard cells is an active process. Potassium transport between the subsidiary cells also appears to be active.Potassium fluxes into the guard cell during stomatal opening were calculated and found to be relatively high. The implications of this are discussed.

Quasi morphine-abstinence syndrome

Abstract: ASSUMING that morphine induces dependence in response to continued interaction of the drug with an unidentified biochemical process of neurones, then suitable pharmacological manipulation might produce a paradigm of the morphine abstinence syndrome in experimental animals not exposed to any opiate If so, the way in which such a quasi-abstinence syndrome was produced might throw light on the endogenous biochemical process involved1

A Cross-Cultural Study of Recognition Memory For Faces

Abstract: The hypothesis that subjects would show superior memory for faces of members of their own ethnic group compared with those of a different ethnic group was tested in a cross-cultural experiment. Thirty two African and 32 European subjects were presented with coloured photographs of ten black Africans and ten white Europeans, with the instruction to try to remember them. Twenty four hours later, the subjects were presented with the same photographs shuffled with an equal number of new photographs of Africans and Europeans, and were asked to identify those they had seen before. The index d' was used as a measure of recognition. As predicted, European subjects were superior at recognising European faces compared with African faces, and African subjects were superior at recognising African faces compared with European faces. Response bias data indicated that European subjects had a differential response bias for the photographs of the two ethnic groups, but African subjects did not differ in their bia...

The Pigments of Reddish Hair and Feathers

Abstract: Despite sporadic investigations over many years the structures of the pigments responsible for most of the yellow, orange, and brown colors of mammalian hair, and of feathers, have remained unknown. However, recent work has shown that the major reddish-brown pigments, gallophaeomelanins, are polymers containing benzothiazole and tetrahydroisoquinoline units. The yellow-orange and violet trichochromes are minor pigments based on a new chromophore, Δ2,2′-bi(1,4-benzothiazine). Both groups arise in vivo from tyrosine and cysteine by a deviation from the biogenetic pathway which normally leads to the formation of eumelanins, the black pigments.

Heats of formation of C1?C4 alkyl nitrites (RONO) and their RO-NO bond dissociation energies

Abstract: The heats of formation of C3 and C4 alkyl nitrites (RONO) have been determined via their heats of combustion by bomb calorimetry, thereby providing a complete set of values of ΔHof for C1-C4 alkyl nitrites. The experimental values are in excellent agreement with values derived from group additivity rules. For branched compounds these calculations involve corrections for gauche interactions. In these cases, the gauche interactions are reflected in the activation energies E1 determined by recent kinetic studies, required for breaking the RO-NO bond. The heats of formation of the alkoxy radicals involved together with ΔHof(NO) = 21.6 kcal/mole leads to the result D(RO-NO) = 41.5 ± 1 kcal/mole. The concordance between D(thermochemical) and D(kinetic), unlike previous kinetic studies, implies that E2 = 0 ± 1 kcal/mole.

The structure and development of septa in Neurospora crassa.

Abstract: Electron microscopy of septa ofNeurospora crassa has shown that microfibrillar material is a major structural component. These microfibrils are arranged in a predominantly tangential orientation and in young (24 hours) mycelium can often be seen in unextracted septal preparations. In older (5 days) mycelium they are overlain with amorphous material, which can be removed by treatment with Pronase, or by chemical extractions. The structure of septa is described and compared with that of the lateral hyphal wall. Developing septa are typically surrounded by vesicles, and sometimes by alignments of cytoplasmic tubules. Electron and light microscopic autoradiography have shown that N-acetylglucosamine is quickly and specifically incorporated into developing septa, and there is no evidence for its prior incorporation into any cytoplasmic site. Glucose is also incorporated into septa, but less specifically. From the autoradiographic results and from experiments with chemical and enzymic extractions it is suggested that chitin is a major component of the septum. A model of the septum is constructed from these data.

Compound Formation and Phase Equilibria in the System PbO-SiO2

Abstract: Compound formation in the system PbO-SiO2 was studied; the results are contrasted with those previously reported. Fifteen binary phases, 4 of which had not been reported, were prepared in the present study. The new phases include Pb5Si8O21, an orthorhombic polymorph of PbSiO3, Pb3SiO5, and a high-SiO2 phase containing ∼ 60 mol% SiO2. It was shown that Pb3SiO5 is thermodynamically stable relative to Pb2SiO4 and 4PbO.SiO2 below 640±5°C. A revised phase equilibrium diagram is presented.

Free-radical grafting of monomers to polydienes. II. Kinetics and mechanism of styrene grafting to polybutadiene

Abstract: A kinetic analysis of the grafting reaction has shown that, provided rubber radicals are not involved in termination reactions, the observed normal kinetics of styrene polymerization are to be expected. An expression relating the graft fraction with the rubber and monomer concentrations has been derived and its validity verified from the results reported in Part I. The observation that the molecular weight of the ungrafted PBD falls during the reaction has been explained on a theoretical basis.

Cicero and Milo

Abstract: The battle of Bovillae on 18th January, 52 B.C., which led to Clodius' death, was literally treated by Cicero in a letter to Atticus as the beginning of a new era—he dated the letter by it, although over a year had elapsed. It is difficult to exaggerate the relief it afforded him from fear and humiliation for a few precious years before civil war put him once more in jeopardy. At one stroke Cicero lost his chief inimicus and the Republic lost a hostis and pestis. Moreover, the turmoil led to a political realignment for which Cicero had been striving for the last ten years—a reconciliation between the boni and Pompey, as a result of which Pompey was commissioned to put the state to rights. Cicero's behaviour in this context, especially his return to the centre of the political scene, is, one would have thought, of capital importance to the biographer of Cicero. Yet two recent English biographies have but briefly touched on the topic. It is true that, in the background of Cicero's personal drama, Caesar and Pompey were taking up positions which, as events turned out, would lead to the collapse of the Republic. However, Cicero and Milo were not to know this, nor were their opponents; friendly cooperation between the two super-politicians apparently was continuing. Politicians on all sides were still aiming to secure power and honour through the traditional Republican magistracies, and in this pursuit were prepared to use the odd mixture of violence, bribery and insistence on the strict letter of the constitution, which was becoming a popular recipe. In retrospect their obsession with the customary organs of power has a certain irony. Yet it is a testimony to the political atmosphere then. Their manoeuvres are also important because both the instability caused by the violence of Clodius and Milo, and the eventual confidence in the rule of law established under Pompey's protection, helped to determine the political position of the boni associated with Pompey in 49 B.C. Cicero's relationship with Milo is at first sight one of the more puzzling aspects of his career. What had they in common, except that Milo, like most late Republican politicians, was at one time associated with Pompey? Properly interpreted, however, this relationship may not only illuminate Cicero's own attitudes but illustrate the character of the last years of Republican politics.

Variation in noradrenaline output with changes in stimulus frequency and train length: Role of different noradrenaline pools

Abstract: 1 During adrenergic nerve stimulation the output/pulse of noradrenaline from the rabbit vas deferens and portal vein is not constant but increases as the stimulus frequency or train length is increased. Depending upon the stimulus frequency and train length the fractional release of noradrenaline may vary from less than 10-7 to greater than 10-4. 2 Endogenous tissue stores of noradrenaline were labelled by incubation with (-)-[3H]-noradrenaline and [14C]-tyrosine. The output/pulse of newly synthesized [14C]-noradrenaline remained constant as the train length was increased whilst the output/pulse of [3H]-noradrenaline increased under the same conditions. This phenomenon was independent of the stimulus frequency. Newly synthesized noradrenaline also appeared in the superfusate following nerve stimulation more rapidly than exogenously loaded noradrenaline. 3 Both [3H]-noradrenaline and [14C]-tyrosine were found to label an easily releasable store of noradrenaline. Mobilization from this store was the same at low and high frequencies of nerve stimulation. 4 It is concluded that at least two functional stores of noradrenaline exist within the adrenergic nerve ending. Newly synthesized noradrenaline is probably only a minor constituent of transmitter output under normal conditions of adrenergic nerve activity. 5 At least two mechanisms control the amount of noradrenaline released per pulse during nerve stimulation. Facilitation of release with increasing train lengths appears to be due to the mobilization of transmitter from a secondary store. Facilitation of release with increasing stimulus frequency is not dependent on mobilization from any particular store and at present there is no satisfactory explanation for this phenomenon.

Concrete and Abstract Terms and Relations in Testing a Rule

Abstract: Subjects have more difficulty in correctly testing a conditional rule stated in abstract form than the same rule given in “thematic” form. The “thematic” form of the rule involves both concrete ter...

Teaching African Children Pictorial Depth Perception: In Search of a Method:

Abstract: Data, suggesting that the exposure of pictorially relatively unsophisticated subjects to stereograms is likely to alleviate their difficulties in perception of pictorial depth in ordinary stimuli, are presented. It is suggested that this remedial measure may prove efficacious in populations that are experiencing such difficulties and are hence handicapped in their use of visual aids.

Control of development of excised fruit bodies and stipes of Coprinus cinereus

Abstract: Excised fruit bodies and stipes of Coprinus cinereus (Schaeff. ex Fr.) S. F. Gray will elongate in the absence of added water or nutrients. The extent of the elongation increases with the initial size of the fruit body, the relative humidity, and the presence of nutrients. The elongation can be reduced or prevented by metabolic inhibitors. There is no evidence for the involvement of growth hormones. The rapid elongation of the stipe can be considered as an autonomous endotrophic process.

Maternal characteristics of women having twin pregnancies

Abstract: A comparison was made between 1308 mothers delivered of twins in Aberdeen between 1950 and 1969 and mothers of singleton infants. There was a greater number of tall women amongst mothers of twins. This was more marked in primigravidae than in multiparae. The rate of twinning was less in thin women than in those who were obese or of normal build. The social class of the husband did not appear to influence the incidence of twins. The rate of weight gain in twin pregnancies, even in early pregnancy, was high compared with the rate in singleton pregnancies. The more frequent occurrence of twinning in heavier, taller women, suggests that nutrition might be responsible but this is not borne out by the findings about social class.

Acid glycosaminoglycan, collagen and elastin content of normal artery, fatty streaks and plaques.

Abstract: The intimal connective tissue plays a major role in atherosclerosis It is directly concerned in the proliferative changes leading to stenosis, and appears to be significantly involved in lipid accumulation The purpose of this paper is to relate the available information on the amounts of acid glycosaminoglycans (GAG), collagen,and elastin in the human intima to the amounts of intact intimai lipoprotein and of bound or precipitated lipid It is clear that there are major gaps in our knowledge, and that this is an area in which further work is urgently required

The effects of nitrogen levels in sitka spruce needles on Elatobium abietinum (Walker) populations in North-Eastern Scotland.

Abstract: In the past seven years five serious outbreaks of E. abietinum have occurred in north-eastern Scotland. These were usually characterised by a rapid build-up of numbers from April to June followed by a sudden drop in late June and early July. Rapidly increasing populations were characterised by low adult/first instar nymph ratios, slowly increasing populations exhibited higher ratios. More alatae were present when aphid numbers were high. This resulted in a decreased production of nymphs. The total soluble nitrogen level in Sitka spruce needles decreased from May to August. Most individual amino acid levels also decreased. Several essential amino acids, including methionine, histidine aud iso-leucine, were in short supply for much of this period. Amino acid levels in aphid extracts also decreased from May to July. The size of the adult aphids remained constant throughout April to late June but dry and fresh weight decreased from late April onwards. The lipid proportion of the dry weight decreased from May to August as did the number of adults bearing embryos. From July onwards a small, decreasing population of aphids existed which showed reduced rates of development and reproduction.

Potentially dangerous surges in an Antrim mudslide

Abstract: Summary Measurements of surface movements and pore-water pressures in a mudslide at Minnis North, north-eastern Ireland, are presented. This feature comprises steep feeder mudslides leading down to a more gently inclined accumulation mudslide, from which a steep front slope descends to the coast road. Frequent surges of the mudslide, which discharges considerable quantities of debris on to this road, are described and discussed. In one of these, pore-water pressures and surface movements were monitored up to failure and the surge itself witnessed by one of the authors. It is concluded that the surges generally originate through‘undrained loading’ of the rear of the accumulation slide by the feeder slides. Attention is drawn particularly to the danger inherent in situations where large volumes of underconsolidated and therefore potentially highly mobile material can collect above a steep front slope and to the difficulty, in the case studied, of obtaining warning of failure. Evidence is also presented to show that this danger is increased if surface streams are present on the mudslide.

Mechanisms of Energy Coupling to the Transport of Amino Acids by Staphylococcus aureus

Abstract: We have studied the effect of artifically imposed transmembrane pH gradients on the uptake of amino acids by Staphylococcus aureus. In high potassium medium, cells treated with valinomycin and tetrachlorosalicylanilide and at Donnan equilibrium, were found to accumulate glutamate. In low potassium medium, addition of acid to the extracellular environment was found to stimulate the uptake of glutamate and aspartate, to induce partial lysine efflux, and to cause a small and transient isoleucine uptake. In conjunction with earlier data from this laboratory (1973), it is concluded that the basic, neutral and acidic amino acids behave, respectively, as cationic, uncharged and anionic sub-strates, accumulating in Staphylococcus aureus in response to (a) the membrane potential, inside negative, (b) the total protonmotive force, and (c) the transmembrane pH gradient, inside alkaline.

DNA replication and RNA transcription of euchromatic and heterochromatic chromosome regions during grasshopper meiosis.

Abstract: The sequence of chromosome replication and the extent of RNA transcription were determined for pre-meiotic S-phase and first meiotic prophase in males of Myrmeleotettix maculatus and Chorthippus parallelus. Some heterochromatic chromosome segments are replicated early in S-phase while others are replicated late. In general, heavily condensed heterochromatic regions of the chromosomes show little or no RNA transcription as defined by 3H-uridine incorporation. Extra (i.e. in excess of 2) M4 autosomes in Ch. parallelus are slightly more condensed (heterochromatic) than their two homologues and this change in coiling behaviour is paralleled by a reduction in the rate of transcription and a change in the time of its replication, more of the DNA being synthesised at the end of S-phase. These findings are discussed in relation to the definition of heterochromatin.

p-fluorophenylalanine and 'division related proteins'

Abstract: CELLS approaching mitosis after completion of DNA synthesis are believed to synthesise certain RNA messages and to translate these in order that proteins essential for mitosis become available1–6. The synthesis during G2 of ‘division-related proteins’ is by no means proven, however, and there is distinctly contradictory evidence in the case of HeLa cells7. The time spent in G2 varies considerably between cell types and the synthesis of proteins involved in the mitotic process might be sufficiently complete by mid S phase in some cell lines while it is only accomplished by late G2 in others. If we assume, however, that proteins specifically related to division are made in G2, then it is of interest to know the latest time that they can be made before division, and what they do.