Showing papers by "University of Aberdeen published in 1988"
TL;DR: Evidence that DNA supercoiling plays a key role in the osmotic induction of proU transcription is presented, and mutations in osmZ are highly pleiotropic, affecting expression of a variety of chromosomal genes including ompF, ompC, fimA, and the bgl operon.
717 citations
TL;DR: In the presence of catalase the oxidation of phenol red was greatly inhibited, although this was dependent upon the concentration of horseradish peroxidase used for the detection of H2O2.
Abstract: 1.
1. Isolated rainbow trout macrophages were stimulated with PMA to release O2− and H2O2, as detected by the reduction of nitroblue tetrazolium (NBT) and the oxidation of phenol red respectively.
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2. The optimal concentration of PMA to elicit the respiratory burst was between 0.2–2 μ g/ml.
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3. Exogenous SOD decreased NBT reduction and enhanced H2O2 production, whereas inhibitors of SOD decreased H2O2 production.
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4. In the presence of catalase the oxidation of phenol red was greatly inhibited, although this was dependent upon the concentration of horseradish peroxidase used for the detection of H2O2.
338 citations
TL;DR: Plasma and platelets represent two distinct pools of PAI‐1, both of which should be considered in studies on the relationship between circulating PAI-1 and thrombotic disease.
Abstract: The distribution of PAI-1 in the plasma and platelets of normal individuals and of patients with platelet abnormalities was studied. An ELISA, capable of measuring PAI-1 in plasma at 1.5 ng/ml, and a functional assay of t-PA inhibition were used to assay platelet-free plasma (PFP), platelet-rich plasma in which the platelets were lysed (PRP) and serum. The PAI-1 concentration of normal PFP was 21.0 +/- 7.2 ng/ml (mean +/- SD) and those of PRP and serum were 282.6 +/- 68.0 and 270.3 +/- 71.9 ng/ml. The concentration of PAI-1 in PRP was proportional to the platelet count with 0.67 +/- 0.18 ng/10(6) platelets. Patients with thrombocytopenia had approximately normal PAI-1 concentrations in PFP; the extremely low concentrations in serum or PRP reflected the platelet count. A patient with grey platelet syndrome showed a comparable pattern, confirming that PAI-1 occurs in the platelet alpha-granules and indicating that the plasma concentration of PAI-1 is independent of the platelet pool of PAI-1. The median inhibitory activities towards t-PA were 1.6, 8.7 and 8.3 units/ml in normal PFP, PRP and serum respectively. PAI-1 in PFP had a median specific activity (units/mg PAI-1) about 5-fold higher than platelet PAI-1. Plasma and platelets represent two distinct pools of PAI-1, both of which should be considered in studies on the relationship between circulating PAI-1 and thrombotic disease.
312 citations
197 citations
TL;DR: In this article, the conductivity of Ca12Al14O33 was investigated and it was shown to be an oxide ion conductor with bulk conductivity only 8-10 times less than that of yttria-stabilized zirconia.
Abstract: Oxide ion conducting solids have much potential for use in fuel cells, sensors, oxygen pumps and gauges. Existing oxide ion conductors are essentially confined to a small group of ceramic oxides with structures related to fluorite, the most important examples being ZrO2- and Bi2O3-related materials. There is a clear need for new oxide ion conductors with improved properties. We report measurements of the conductivity of Ca12Al14O33, which indicate it to be an oxide ion conductor with bulk conductivity only 8–10 times less than that of yttria-stabilized zirconia. The structure of Ca12Al14O33 is unrelated to the fluorite structure. The reasons for the high conductivity are not well understood but may be associated with the fact that the structure contains a mixture of anions, a three-dimensional aluminate framework and essentially free oxide ions.
189 citations
TL;DR: Scientific Discovery: Computational Explorations of the Creative Processes examines the role of language in the creative process and the role that language plays in the development of science.
Abstract: Scientific Discovery: Computational Explorations of the Creative Processes. By Pat Langley, Herbert A. Simon, Gary L. Bradshaw and Jan M. Zytkow. Cambridge Mass., USA, The MIT Press, USD 13.50.
179 citations
TL;DR: In this paper, radiocarbon dating and other age determinations suggest that glaciers readvanced significantly only during the last 5 ka, reaching positions from several 100 m to a few kilometres beyond their present limits.
176 citations
167 citations
Journal Article•
TL;DR: Both respiratory burst activity and bactericidal activity were enhanced after incubation of resident or elicited macrophages with the MAF-containing supernatants for 48-72 hr and a continuous presence of MAF was necessary for maximal stimulation.
Abstract: Rainbow trout head kidney and blood leucocytes are shown to be capable of secreting a soluble macrophage-activating factor (MAF) after stimulation with concanavalin A (Con A). The presence of phorbol myristate acetate (PMA) as a co-stimulant increased the production of MAF. Both respiratory burst activity (nitroblue tetrazolium, NBT, reduction and H2O2 production) and bactericidal activity were enhanced after incubation of resident or elicited macrophages with the MAF-containing supernatants for 48-72 hr. The target culture period before the addition of MAF did not affect their responsiveness, but a continuous presence of MAF was necessary for maximal stimulation.
161 citations
TL;DR: Strong and weak immunoreactivity was identified in hepatocytes, columnar absorptive epithelial cells of the small intestine, polymorphonuclear leucocytes and their precursors in the bone marrow, and in mast cells, and Immunoreactivity could not be demonstrated in the adrenal gland, placenta, colonic epithelium and alveolar type II cells and Clara cells ofThe lung.
Abstract: 1. The localisation and distribution of cytochrome P-450 in human tissues has been studied by immunocytochemistry using a monoclonal antibody to a major form of human hepatic cytochrome P-450, P-450hA7, which is closely related to cytochromes P-450 HLp and P-450NF. 2. Strong immunoreactivity was identified in hepatocytes, columnar absorptive epithelial cells of the small intestine, polymorphonuclear leucocytes and their precursors in the bone marrow, and in mast cells. 3. Weak immunoreactivity was present in the proximal tubules of the kidney, pancreatic acini, gall bladder epithelium, squamous epithelium and sebaceous glands of the skin, interstitial cells of the testis and luteal cells of the ovary. 4. Immunoreactivity could not be demonstrated in the adrenal gland, placenta, colonic epithelium and alveolar type II cells and Clara cells of the lung.
151 citations
TL;DR: The groves are characterized by high inputs of leaf litter in the dry season, extensive colonization of surface organic matter by ectomycorrhizas and hyphal strands, and high carbon: extractable inorganic phosphorus ratios in the mineral soil in the wet season.
Abstract: SUMMARY
The mycorrhizal status of a group of caesalpinioid legumes in lowland rain-forest in Korup National Park, SW Cameroon, was examined. Species in ten genera, Anthonotha, Aphanocalyx, Berlinia, Didelotia, Gilbertiodendron, Julbernardia, Microberlinia, Monopetalanthus, Tetraberlinia(tribe Amherstieae) and Afzelia(tribe Detarieae) were ectomycorrhizal. These species were not uniformly distributed in the forest, and three large emergent species Microberlinia bisulcata A. Chev., Tetraberlinia bifoliolata(Harms) Hauman, and T. moreliana Aubr. in particular appear to form groves c. 600 m across. This type of distribution may be related to the ectomycorrhizal habit.
A previous large scale enumeration and soil survey on four 5 km transects of plots in the forest, carried out during the wet season, had revealed an association between these ectomycorrhizal legumes and low concentrations ( 5 μg g-1) of extractable phosphorus in the mineral soil. In the current study part of one of the original transects in a low phosphorus area of the forest, where ectomycorrhizal trees comprise 29 % of the basal area, was resampled at the subplot level during the dry season. Whereas in the wet season soil phosphorus had been lower (2·8 μg g-1) within the ectomycorrhizal groves than without (3·8 μg g-1), in the dry season the situation was reversed and the overall concentrations were higher (12·3 and 7·9 μg g-1 respectively). Ordination analysis re-affirmed the association of the three Microberlina/Tetraberlinia species with relatively low concentrations of extractable phosphorus in the wet season but relatively high ones in the dry season. The groves are characterized by high inputs of leaf litter in the dry season, extensive colonization of surface organic matter by ectomycorrhizas and hyphal strands, and high carbon: extractable inorganic phosphorus ratios in the mineral soil in the wet season. These features are discussed in relation to the presumed ability of ectomycorrhizas to utilize organic phosphorus.
TL;DR: In cultured human hepatoma cells phenolphthalein glucuronidation was increased 3-fold by 2 mM phenobarbitone in the culture medium but not by 25 microM benz(a)anthracene (BA), while 1-naphthol glucuronidated was not increased by either PB or BA, suggesting induction of different cytochrome P-450 isoenzymes.
TL;DR: Although there appeared to be a decline in NART performance in the Korsakoff and Huntington's groups, it did provide a significantly higher IQ estimate than the Vocabulary sub-test.
Abstract: The validity of premorbid IQ estimates provided by the National Adult Reading Test (NART) and Vocabulary sub-test of the Wechsler Adult Intelligence Scale were evaluated, by comparison with matched, healthy control subjects, in Korsakoff psychosis, alcoholic dementia, dementia Alzheimer type (DAT), multi-infarct dementia (MID), Huntington's disease, and closed head injury (CHI). There was no significant difference in NART performance between control subjects and the alcoholic dementia, DAT, MID, and CHI groups. Although there appeared to be a decline in NART performance in the Korsakoff and Huntington's groups, it did provide a significantly higher IQ estimate than the Vocabulary sub-test. All clinical groups, with the exception of the CHI group, performed at a significantly lower level than the control group on the Vocabulary sub-test.
TL;DR: It is suggested that an increase in the blood PGE2 level may contribute to the pathogenesis of fever.
TL;DR: Using this assay, the authors have shown that normal macrophages are able to kill an A-layer lacking strain of A. salmonicida but not an A -layer possessing strain (048), and macrophage activated in vivo were shown to be capable of killing both strains effectively.
Abstract: . A novel assay to detect macrophage bactericidal activity is reported. It utilizes the reduction of a tetrazoiium dye, MTT, to colorimetrically detect the number of surviving bacteria after incubation with the macrophages. This assay has been optimized for the killing of Aeromonas salmonicida and its advantages over conventional colony counting are discussed. Using this assay, the authors have shown that normal macrophages are able to kill an A-layer lacking strain of A. salmonicida (004) but not an A-layer possessing strain (048). In contrast, macrophages activated in vivo were shown to be capable of killing both strains effectively.
TL;DR: The case is made for estimating absolute values using stereological principles rather than relying on planar data (profile areas, perimeter lengths, numbers, apparent thicknesses) without resorting to expensive measuring devices.
TL;DR: In this paper, a suite of alkali feldspars from the Klokken syenite intrusion (U-Pb age 1166 ± 4 Ma ) have been fully characterized by transmission electron microscopy.
Journal Article•
TL;DR: An immunoregulatory role in conditions in which retinal autoimmunity is implicated, such as chronic idiopathic posterior uveitis and retinal vasculitis is postulated for these cells.
Abstract: A possible role for retinal pigment epithelial cells (RPE) as local antigen presenting cells in immune inflammatory eye disease was investigated by studying the in vitro response of human RPE cells to stimulation with purified IFN-gamma or Con A induced lymphokine. RPE cells cultured with a single dose of 50-1000 u/ml IFN-gamma for up to 8 days to allow maximal Class II gene transcription, expressed HLA DP, DR and DQ antigens in a dose-dependent manner with 80% or more of cells positive for each antigen at the higher concentration. After removal of a suboptimal IFN-gamma stimulus, HLA-DR antigen expression persisted for at least 15 days. HLA-DP and DQ antigens persisted only after maximal IFN-gamma stimulation. Lymphokine from Con A stimulated lymphocytes induced higher levels of DR and DQ expression (80%) over DP (15%) implying complex interactions with other mediators present in the lymphocyte culture supernatant. Since RPE cells phagocytose and recycle autoantigen-rich retinal rod outer segments and co-express HLA DR and DQ Class II antigens in response to IFN-gamma stimulation, an immunoregulatory role in conditions in which retinal autoimmunity is implicated, such as chronic idiopathic posterior uveitis and retinal vasculitis is postulated for these cells.
TL;DR: In this paper, the peak-shift method was used for a narrow molecular weight fraction of atactic polystyrene by using differential scanning calorimetry during the heating stage of well-defined three-step thermal cycles.
Abstract: The structure parameter x (also known as the nonlinearity parameter), which in the KAHR model determines the relative contributions of temperature and structure to the retardation times of polymers in the glass transition region, is evaluated experimentally for a narrow molecular weight fraction of atactic polystyrene by the peak-shift method. This method is based on the dependence on heating rate and annealing time of the endothermal peak temperatures Tp, obtained by differential scanning calorimetry during the heating stage of well-defined three-step thermal cycles. The results obtained from the shifts of Tp, with both heating rate and the amount of isothermal recovery during the annealing stage before reheating, are consistent with the theoretical predictions of the KAHR model. The appropriate analysis of the data for a polystyrene fraction of molecular weight 30,100 leads to a value of x = 0.46 ± 0.02. Furthermore, this value of x is constant for a wide range of annealing times and heating rates and for two different annealing temperatures, in full agreement with the theoretical model. The advantages of the peak-shift method over that used by most other workers, the curve-fitting method, are critically discussed.
TL;DR: Assemblages of dinoflagellate cysts of Cenomanian-Turonian age recovered from sequences containing bituminous marls in the Lower Saxony Basin, Helgoland and eastern England vary in composition according to lithofacies and palynofacies.
TL;DR: In this article, it was shown that when estimates made over periods which do not exactly equal 24 hr are corrected to a daily, or hourly rate, and when CO 2 production is also variable, an error is introduced.
TL;DR: Modified Earle's medium was more effective in this respect than Williams' E medium and increased the O‐dealkylations of ethoxyresorufin, benzyloxyres orufin and pentoxyresOrufin 50‐, 30‐ and 10‐fold, respectively.
TL;DR: The results show that the induction of the dimorphic transition in this organism is accompanied by a steep rise in internal pH, which is not known whether these changes are the cause or consequence of morphogenesis.
Abstract: SUMMARY: Weak acids were used to measure the internal pH of yeast cells of Candida albicans that had been induced to form buds or germ tubes. Under conditions that supported germ tube formation the internal pH rose from around 6.8 to over 8.0 after 30 min in two different induction media. Internal pH measured by 31P NMR confirmed this pattern and also showed that the internal pH fell to around 7.0 prior to the outgrowth of germ tubes. Conditions which led to budding induced less cytoplasmic alkalinization. This alkalinization was brought about when cells were inoculated into media of neutral pH and at an increased temperature. Increasing the temperature of the medium augmented the alkalinization of the cytoplasm induced by raising the external pH. Strains of C. albicans defective in the ability to produce germ tubes did not show this dramatic cytoplasmic alkalinization under conditions which normally supported filamentous growth. The raising of internal pH may be due to the activation of the plasma membrane proton-pumping ATPase since diethylstilboestrol inhibited the cytoplasmic alkalinization and germ tube formation without causing irreversible loss of cell viability. The results show that the induction of the dimorphic transition in this organism is accompanied by a steep rise in internal pH. It is not known whether these changes are the cause or consequence of morphogenesis.
TL;DR: Patients' call for help and the doctors' response may be at an instinctive level according to the patients' distress; these patterns of behaviour may be difficult to modify by public education.
Abstract: The longest component of the total delay in coming under coronary care is patient delay, and it has been suggested that public education might be used to make it shorter. The patterns of patient delay were studied in 450 patients with acute myocardial infarction uncomplicated by cardiac arrest out of hospital, of whom 243 had a previous history of ischaemic heart disease. Patient delays had a skewed distribution with a modal delay of up to one hour, a median delay of two hours, and a mean delay of 10 hours. Two thirds of patients had sought help from their general practitioners within four hours of the onset of symptoms. During the first four hours the longer that patients delayed the lower was the subsequent mortality (27%, 18%, and 9% for delays of one hour or less, up to two hours, and up to four hours, respectively), but patients who delayed four to eight hours had the highest mortality of all (38%). Neither the median value nor the pattern of patient delays was altered by a previous history of ischaemic heart disease. There were pronounced differences in doctor delays, depending on the patient9s age, delay time, and ultimate place of treatment, showing that the doctors9 behaviour was influenced before they had seen their patients. Nevertheless, the median total delay for patients aged up to 70 was one hour 35 minutes, and a higher proportion of patients were seen early after infarction than in recent hospital trials of thrombolytic treatment. These findings suggest that the patients9 call for help and the doctors9 response may be at an instinctive level according to the patients9 distress; these patterns of behaviour may be difficult to modify by public education.
TL;DR: The hypothesis considered in this paper is that the secular decline in mortality rates can be attributed to the secular rise in real per capita income and that the remaining fluctuations in mortality rate can be explained by cyclical movements in income and variations in unemployment.
Abstract: The relationship between unemployment and health status is examined in a comparative study of five European countries using a time series model. "The hypothesis considered in this paper is that the secular decline in mortality rates can be attributed to the secular rise in real per capita income and that the remaining fluctuations in mortality rates can be explained by cyclical movements in income and variations in unemployment." The data concern the Federal Republic of Germany, France, Italy, Sweden, and Ireland.
TL;DR: The Caminada-Moreau barrier headland of South Louisiana is a low-profile beach and dune coastline that is transgressing rapidly over the surfaces of the abandoned Lafourche delta complex.
TL;DR: The requirements and advantages of multiple group principal component analysis (MGPCA) when it is used to investigate population differentiation are explored and it is shown that MGPCA per se does not require equality of variance along the axes although it may be a requirement of some of the techniques subsequently used to analyse the component scores.
Abstract: This paper explores the requirements and advantages of multiple group principal component analysis (MGPCA) when it is used to investigate population differentiation. A distinction is drawn between equality of orientation of the within-group axes and equality of variance along these axes. Several examples of the use of MGPCA are discussed and it is shown that MGPCA per se does not require equality of variance along the axes although it may be a requirement of some of the techniques subsequently used to analyse the component scores. MGPCA is simple and direct, being based on the mathematically well defined eigenvector analysis of a symmetric positive definite (pooled within-group covariance) matrix and it can be thought of as a step in the computation of canonical variate analysis (CVA). It can be used with CVA (which is the most popular method of biometrically assessing population affinities) to assess the contribution of within-group components to among-group discrimination. It is also one of a range of appropriate techniques that can be used to define (and delete if required) within-group growth effects and is particularly suitable when CVA is being used to assess the population affinities. When used in this way it has the advantage of being more influenced by the groups with the greatest growth range.