Showing papers by "University of Glasgow published in 1978"

Antigenic variation in trypanosomes

Abstract: In its mammalian host, Trypanosoma brucei is able to change the antigenic character of its glycoprotein surface coat and so evade the host's immune response. This phenotypic change seems to occur spontaneously in 1 in 10,000 individuals but is not due to genetic mutation: host antibody is not necessary for its induction but plays a selective part in bringing about the gross changes in parasite numbers and antigenic character observed in the bloodstream by destroying the main component of what is actually a heterogeneous population. The infecting trypanosome population injected into the mammalian host by the tsetse fly vector may also be heterogeneous. Such heterogeneity complicates plans to vaccinate cattle and people against the African trypanosomes based on the premise that the metacyclic trypanosomes of a clone bear the same surface antigen.

Carotenoids in photosynthesis

Abstract: Carotenoids are usually considered to perform two major functions in photosynthesis. They serve as accessory light harvesting pigments, extending the range of wavelengths over which light can drive photosynthesis, and they act to protect the chlorophyllous pigments from the harmful photodestructive reaction which occurs in the presence of oxygen. Drawing upon recent work with photosynthetic bacteria, evidence is presented as to how the carotenoids are organized within both portions of the photosynthetic unit (the light harvesting antenna and the reaction centre) and how they discharge both their functions. The accessory pigment role is a singlet-singlet energy transfer from the carotenoid to the bacteriochlorophyll, while the protective role is a triplet-triplet energy transfer from the bacteriochlorophyll to the carotenoid.

The Regulation of Glycogen Metaabolism

Abstract: Inhibitor-1 is a protein which inhibits phosphorylase phosphatase only when it has been phosphorvlated by cyclic-AMP-dependent protein kinase [Huang, F. L. and Glinsmann. W. H. (1976) Eur. J. Biochem. 70, 419–426]. Inhibitor-1 was purified by a heat treatment at 90°C, precipitation with ammonium sulphate, chromatography on DEAE-cellulose, gel filtration on Sephadex G-100, and finally recromatography of the phosp0horylated protein on DEAE-cellulose. The protein was purified 4000-fold and 1.5 mg per 1000 g muscle was obtained in seveven days corresponding to an overall yield of 15–20%. The purified protein was in a state approaching homogeneity as judged by the criteria of polyacrylamide-gel electrophoresis and ultracentrifugal analysis. The concentration of inhibitor-1 in vivo was calculated to be 1.5 μMM, which is at least as high as the concentrationof phosphorylase phosphatase. The amino acid composition of inhibitor-1 showed several unusual features. Glutamic acid and proline accounted for nearly one third of the residues, tyrosine, tryptophan and cysteine were absent, and the content of aromatic amino acids was very low. The molecular weight measured by sedimentation equilibraium centrifugation was 19 200 and by amino acid analysis was 20 800. These values were lower than the mol. wt of 26000 determined empirically by gel electrophoresis in the presence of sodium dodecyl sulphate, and much lower than the apparent molecular weitht of 60000 estimated by filtraation on Sephadex G-100. The gel filtration behaviour, stability to heating at 100°C and amino acid composition suggest than inhibitor-1 may possess little ordered structure. The phosphorylated form of inhibitor-1contained close to one molecule of covalently bound phosphate per mole of protein, which is consistent with previous finding of a unique decapeptide sequence at the site of phosphorylation, Ile-Arg-Arg-Arg-Arg-Pro-Thr(p-Pro-Ala-Thr-[Cohen, P., Rylatt, D. B. and Nimmo, G. A. (1977) FEEBS Lett. 76, 182–186]. The phosphorylated form of inhibitor-1 inhibited phosphorylase activity (0.02 U) by 50% at a concentration of only 7.0 nM in the standard assay, but the phosphorylated decapeptide was 1000–2000 times less effective as an inhibitor.

Probability and Statistical Inference

Abstract: 1. Empirical and Probability Distributions. Basic Concepts. The Mean, Variance, and Standard Deviation. Continuous-Type Data. Exploratory Data Analysis. Graphical Comparisons of Data Sets. Time Sequences. Probability Density and Mass Functions. 2. Probability. Properties of Probability. Methods of Enumeration. Conditional Probability. Independent Events. Bayes' Theorem. 3. Discrete Distributions. Random Variables of the Discrete Type. Mathematical Expectation. Bernoulli Trials and the Binomial Distribution. The Moment-Generating Function. The Poisson Distribution. 4. Continuous Distributions. Random Variables of the Continuous Type. The Uniform and Exponential Distributions. The Gamma and Chi-Square Distributions. The Normal Distribution. Distributions of Functions of a Random Variable. Mixed Distributions and Censoring. 5. Multivariable Distributions. Distributions of Two Random Variables. The Correlation Coefficient. Conditional Distributions. The Bivariate Normal Distribution. Transformations of Random Variables. Order Statistics. 6. Sampling Distribution Theory. Independent Random Variables. Distributions of Sums of Independent Random Variables. Random Functions Associated with Normal Distributions. The Central Limit Theorem. Approximations for Discrete Distributions. The t and F Distributions. Limiting Moment-Generating Functions. Chebyshev's Inequality and Convergence in Probability. Importance of Understanding Variability. 7. Estimation. Point Estimation. Confidence Intervals for Means. Confidence Intervals for Difference of Two Means. Confidence Intervals for Variances. Confidence Intervals for Proportions. Sample Size. Distribution-Free Confidence Intervals for Percentiles. A Simple Regression Problem. More Regression. 8. Tests of Statistical Hypotheses. Tests about Proportions. Tests about One Mean and One Variance. Tests of the Equality of Two Normal Distributions. Chi-Square Goodness of Fit Test. Contingency Tables. Tests of the Equality of Several Means. Two-Factor Analysis of Variance. Tests Concerning Regression and Correlation. The Wilcoxon Tests. Kolmogorov-Smirnov Goodness of Fit Test. Resampling Methods. Run Test and Test for Randomness. 9. Theory of Statistical Inference. Sufficient Statistics. Power of a Statistical Test. Best Critical Regions. Likelihood Ratio Tests. Bayesian Estimation. Asymptotic Distributions of Maximum Likelihood Estimators. 10. Quality Improvement through Statistical Methods. Statistical Quality Control. General Factorial and 2k Factorial Designs. More on Design of Experiments. Epilogue.Appendix A. Review of Selected Mathematical Techniques. Algebra of Sets. Mathematical Tools for the Hypergeometric Distribution. Limits. Infinite Series. Integration. Multivariate Calculus. Appendix B. References.Appendix C. Tables.Appendix D. Answers to Odd-Numbered Exercises.Index.

High incidence area of cattle cancer with a possible interaction between an environmental carcinogen and a papilloma virus

Abstract: Cattle in upland areas of Scotland and northern England are substantially more prone to alimentary cancer than those of the immediately neighbouring lowlands, and epidemiological evidence implicates a combination of papilloma virus and bracken in the aetiology of the disease. Here Professor Jarrett outlines the circumstantial case against these agents and discusses its implications.

Genetic Control of Susceptibility and Resistance to Parasitic Infection

Abstract: Publisher Summary Susceptibility or resistance of a host species to parasitic infection is the product of a variety of factors that influence the host–parasite relationship at many points. The chapter discusses some examples of genetically controlled variation in response to parasites operating at the intraspecific level, because such variations offer, through comparison of infections in different host strains and by selective breeding programs, scope for experimental investigation of the mechanisms responsible. The chapter discusses the parasites in animal hostsand the genetics of plant host–parasite relationships. It illustrates examples where susceptibility and resistance have been or could reasonably be interpreted in relation to the operation of immunological responses imposing restraints upon the development and persistence of parasites. Recognition of this fact offers the possibility of an exciting re-evaluation of the response of hosts to parasitic infection and may allow an analysis of the immune response in terms, which clarify both the underlying genetic and immunological mechanisms.

Precambrian solution photochemistry, inverse segregation, and banded iron formations

Abstract: SOLAR radiation on an early Precambrian sea would generate short-lived excited species near the surface of the water. Many of the species would be powerful oxidising or reducing agents. Despite back-reactions, net reducing power would be lost to the atmosphere. This effect would be the opposite of present day photosynthesis and can be termed ‘inverse segregation’. Its possible relevance to banded iron formation is discussed here.

The control of cell division by tension or diffusion.

Abstract: SEVERAL types of experiment which have been interpreted as evidence for the control of cell division by the action of diffusion boundary layers can equally well be interpreted as being due to the action of mechanical effects. The pumping experiment, and wounding experiments1 have all been interpreted as evidence that increasing the rate of exchange of metabolites between cell and medium stimulates the cell cycle and in particular the transition G0 to S. However, there is already much observational evidence that suggests that mechanical stress may lead to increased division2–4. The pumping and wounding5 experiments might mechanically stress cells so that it is timely to carry out an experiment which distinguishes between the effects of mechanical tension and the effects of changed diffusion rates. We provide experimental evidence that mechanical tension may stimulate the cell cycle in vertebrate cells.

Influence of the fire retardant ammonium polyphosphate on the thermal degradation of poly(methyl methacrylate)

Abstract: The thermal degradation of ammonium polyphosphate (APP), a commercial fire retardant, and its blends with poly(methyl methacrylate) (PMMA) have been studied by thermal volatilization analysis (TVA) and the degradation products identified. APP degrades under vacuum in three stages. Initially it condenses to an ultraphosphate ( 370°C). In the presence of APP, the normal depolymerization of PMMA to monomer competes with degradation reactions which form high-boiling chain fragments, methanol, carbon monoxide, dimethyl-ether, carbon dioxide, hydrocarbons, and char. These additional reactions are initiated principally by the PPA. Intramolecular cyclization occurs, resulting in the formation of anhydride, and ester groups are eliminated, methanol and carbon monoxide being evolved. Further degradation of the modified polymer leads to the other volatile products and the char.

Immunity to intestinal parasites

Abstract: Intestinal parasites are common in man and animals and can cause severe disease. Knowledge of immunity to such infections is limited and comes largely from studies using laboratory host-parasite systems. Understanding how immunity can operate, and why it often does not, is not only of intrinsic interest but necessary for the development of immunological methods of control.

An algorithm for optimal designs on a design space

Abstract: Two variations of a simple monotunic algorithm for computing optimal designs on a finite design space are presented. Various properties are listed. Comparisons witn other algorithms are made.

The regulation of glycogen metabolism. Phosphorylation of inhibitor-1 from rabbit skeletal muscle, and its interaction with protein phosphatases-III and -II.

Abstract: Inhibitor-1 from rabbit skeletal muscle was phosphorylated by protein kinase dependent on adenosine 3' :5'-monophosphate (cyclic AMP), but not by phosphorylase kinase or by glycogen synthetase kinase-2. Protein phosphatase-III, isolated and stored in the presence of manganese ions to keep it stable, was in a form which catalysed a rapid dephosphorylation and inactivation of inhibitor-1. The kinetic constants for the dephosphorylation of inhibitor-1 [Km = 0.7 micron, V(rel) = 40] were comparable to those for the dephosphorylation of phosphorylase kinase [Km =1.1 micron, V (rel) = 62] and phosphorylase [Km = 5.0 micron, V (rel) = 100]. The dephosphorylation of inhibitor -1 was inhibited by inhibitor-2, indicating that it was catalysed by protein phosphatase-III, and not by another enzyme that might be contaminating the preparation. When protein phosphatase-III was diluted into buffers containing excess EDTA, it lost activity initially, but after 90 min, the activity reached a plateau that remained stable for at least 20h. The initial loss in activity varied with the substrate that was tested; it was 20-30% with phosphorylase a, 50-60% with phosphorylase kinase and greater than or equal to 95% with inhibitor-1. This form of protein phosphatase-III was inhibited by inhibitor-1 in a noncompetitive manner, and the Ki for inhibitor-1 was 1.6 +/- 0.3 nM. The phosphorylase phosphatase, phosphorylase kinase phosphatase and glycogen synthetase phosphatase activities of protein phosphatase-III were inhibited in an identical manner by inhibitor-1. This result emphasizes the potential importance of inhibitor-1 in the regulation of glycogen metabolism, since it can influence the state of phosphorylation of three different enzymes. The formation of the inactive complex between inhibitor-1 and protein phosphatase-III was reversed by incubation with trypsin (which destroyed inhibitor-1, but not protein phosphatase-III) or by dilution of the inactive complex. Kinetic studies, using the form of protein phosphatase-III which dephosphorylated inhibitor-1 very rapidly, demonstrated three unusual features of the system: (a) inhibitor-1 was still as powerful and inhibitor of the dephosphorylation of phosphorylase a and phosphorylase kinase a even under conditions where it was being rapidly dephosphorylated; (b) inhibitor-1 was not an inhibitor of its own dephosphorylation; (c) phosphorylase a did not effect the rate of dephosphorylation of inhibitor-1 even when it was present in a 50-fold molar excess over inhibitor-1. The result of these three properties is that inhibitor-1 is preferentially dephosphorylated by protein phosphatase-III even in the presence of a large excess of other phosphoprotein substrates. Inhibitor-1 was also dephosphorylated by protein phosphatase-II. The kinetic constants for the dephosphorylation of inhibitor-1 [Km = 2.8 micron, V (rel) = 200] and the alpha-subunit of phosphorylase kinase [Km = 3.7 micron, V (rel) = 100]were comparable...

The frequency of occurrence of feline leukaemia virus subgroups in cats

Abstract: Feline leukaemia viruses (FeLV) were isolated from cats in Glasgow and New York with lymphosarcoma and from apparently healthy carrier cats. The subgroup composition of each isolate was determined. All isolates contained FeLV of subgroup A(FeLV-A) and a high proportion also contained subgroup B virus (FeLV-B). Virus of subgroup C (FeLV-C) was rare and occurred in association with FeLV-A and, in some isolates, with FeLV-B as well. The same pattern was observed in isolates from British and American cats. The frequency of FeLV subgroups was different in cats with lymphosarcoma and in healthy carrier cats. In cats with lymphosarcoma, 42% had FeLV-A and 58% had FeLV-AB; there was no obvious correlation between virus subgroup and type of disease. In FeLV-positive healthy cats, 65% had FeLV-A and 33% had FeLV-AB. FeLV-C was isolated only from cats with disease. The healthy carrier cats were from multiple-cat households (MCH). Two distinct types of FeLV-infected MCH were found: MCH-A in which the carrier cats yielded only FeLV-A, and MCH-AB in which cats with either FeLV-A or FeLV-AB were present. In MCH-AB half of the cats had FeLV-A and half had FeLV-AB. Overall, the proportion of cats in MCH which were viraemic with FeLV was 42%. However, there was a marked difference in the prevalence of carrier cats in each type of MCH: in MCH-A, 28% were FeLV-positive while in MCH-AB, 53% were viraemic.

Estimation of Correlation Coefficients by Ellipsoidal Trimming

Abstract: The ellipsoid of minimal content containing a set of points is used as a trimming device and as a direct means of estimating correlation coefficients for mid‐truncated data. Numerical results are presented for simulated data and for Fisher's data from Iris setosa plants.

Thermal degradation of the polyurethane from 1,4-butanediol and methylene bis(4-phenyl isocyanate)

Abstract: A polyurethane prepared from 1,4-butanediol (BD) and methylene bis(4-phenyl isocyanate) begins to evolve volatile degradation products at approximately 240°C By a combination of thermal analysis methods (TVA, TG, and DSC) and examination of the volatile and involatile products by using a combination of GLC and infrared and mass spectrometric analysis, it is shown that the total reaction comprises a primary depoly-condensation process in which the two monomers are formed, followed by the subsequent reaction of these monomers to form the volatile products, tetrahydrofuran, dihydrofuran, carbon dioxide, water, butadiene, hydrogen cyanide, and carbon monoxide and residual carbodiimide and urea structures A mechanism, which accounts for all these products, has been formulated and tested

Interfacial slip and damping in fibre reinforced composites

Abstract: The effect of interfacial slip on the stress—strain properties of a rubbery polymer reinforced with short fibres is discussed with particular reference to hysteresis. The amount of energy dissipated by interface sliding and by the viscoelastic response of the matrix is calculated in the light of a simple model. This is compared with the dynamic properties of the composites, both with a view to designing composites with a useful combination of stiffness and damping, and also with the possibility of evaluating the integrity of the fibre-matrix interface from dynamic measurements.

The Marxist theory of the labour aristocracy

Abstract: (1978). The Marxist theory of the labour aristocracy. Social History: Vol. 3, No. 1, pp. 61-82.

Chronic Obstructive Pulmonary Disease (COPD): Identification of Affected Horses

Abstract: SUMMARY Mean normal values for PaO2 and max Δ Ppl for horses were determined. Using 2 standard deviations below (PaO2) and above (max Δ Ppl) the mean normal values as a guide, horses affected with COPD were satisfactorily distinguished from other horses in a series of 100 animals. The frequency of occurrence of 20 different clinical parameters in affected, not affected and possibly affected horses was examined statistically. Poor work performance and a history of previous febrile illness occurred more often in COPD horses than in others. The presence of a chronic cough, dyspnoea, double expiratory effort, increased breathing sounds, wheezing and crepitant breathing sounds occur more frequently in COPD horses than in others and the presence of prolonged coughing was highly indicative of COPD. Crepitant breathing sounds (observed only in horses in the affected group), wheezing and increased respiration sounds were observed in a high proportion of horses affected with COPD, but a diagnosis of COPD based solely on these parameters would lead to an unacceptably low number of cases being recognised. While radiological examination appeared to be helpful, x-ray films were in general difficult to interpret. Haemato-logical examination was of no help in the diagnosis of COPD. The beneficial effect of removing affected horses from contact with hay and straw was recorded. RESUME Les valeurs moyennes normales de PaO2 et les valeurs maximales de Ppl ont ete determinees chez le cheval. En employant les deviations standards au dessous pour PaO2 et au dessus pour Ppl des valeurs moyennes, on peut distinguer les chevaux atteints dans une serie de 100 chevaux. La frequence d'apparition de 20 parametres cliniques differents fut determinee de maniere statistique pour les chevaux atteints, suspects et indemnes. Une aptitude physique insuffisante et les commemoratifs d'une maladie febrile anterieure ont ete constates plus souvent chez les chevaux atteints de MPCO. L'existence d'une toux chronique, de dyspnee, d'une expirationa deux temps et les bruits respiratoires crepitants ou sifflants est plus frequente chez les chevaux atteints de MPCO que chez les autres. Les bruits respiratoires crepitants (seulement observes chez les chevaux atteints de MPCO), les bruits respiratoires sifflants et l'intensite accrue des sons respiratoires furent constates chez un grand nombre de chevauxa MPCO; toutefois le diagnostic de MPCO etaye par ces seuls parametres serait par trop restrictif. Les examens radiologiques furent utiles mais les cliches furent trop souvent difficilesa interpreter. L'hematologie n'apporta aucune aide. On nota l'interet qu'il y avait de soustraire les animaux malades du contact des fourrages, paille ou foin. ZUSAMMENFASSUNG Normale Durchschnittswerte fur PaO2 und Δ Ppl max wurden bestimmt. Die Verwendung von zwei Standard-abweichungen unter (PaO2) oder uber (Δ Ppl max) dem Mittelwert erlaubte die zufriedenstellende Unterscheidung von Pferden mit COPD und von anderen Pferden in einer Reihe von 100 Tieren. Die Frequenz des Auftretens von 20 verschiedenen klinischen Parameter bei befallenen nicht befallenen und moglicherweise befallenen Pferden wurde statistisch analysiert. Ungenugende Leistungs-fahigkeit und eine Anamnese von durchgemachten febrilen Zustanden wurde bei COPD-Pferden ofter vermerkt als bei anderen. Das Vorliegen eines chromischen Hustens, von Dyspnoe, einer doppelschlafigen Exspiration, vermehrter Atemgerausche, Giemen und krepitierender Auskultationsgerausche wird bei COPD Pferden haufiger festgestellt als bei anderen und ein langdauernder Husten ist ein guter Indikator fur COPD. Krepitierende Auskultationsgerausche (nur bei befallenen Pferden vorhanden), Giemen und verstarkte Atemgerausche konnten bei der Mehrzahl von COPD Pferden festgestellt werden, aber eine Diagnose von COPD, die sich nur auf diese Parameter stutzte, wurde zu einer zu kleinen Anzahl erkannter Falle fuhren. Wenn auch die Rontgenuntersuchung helfen mag, bleiben doch die Aufnahmen in der Regel schwierig zu interpretieren. Die haematologische Untersuchung war keine Hilfe fur die Diagnose von COPD. Die gunstigen Auswirkungen der Elimination von Heu und Stroh auf affizierte Pferde wurden festgehalten.

A review of the effects of trace concentrations of anaesthetics on performance

Abstract: The professional performance of the anaesthetist is a subject of enormous importance which has been subjected to very little scientific scrutiny. From a questionnaire sent to junior hospital doctors of all specialties, Wilkinson, Tyler and Varey (1975) elicited that more than one-third of medical staff below the grade of registrar believed they suffered an impairment of working efficiency as a result of fatigue. Symptoms which were reported included irritability, inability to speak, tiredness and slowing of thought processes. Junior anaesthetists also believed that breathing anaesthetic waste gases contributed to fatigue and impaired working efficiency. affect performance. Performance following recovery from clinical doses of anaesthetic agents has been discussed recently in an excellent, comprehensive review by Drummond (1975) and this aspect will not be considered here. It is now generally accepted that working in the operating theatre environment is associated with an increase in health hazards. Although the direct cause of this problem has not been established, complaints of headaches by anaesthetists working with unscavenged anaesthetic circuits, data demonstrating illeffects in laboratory animals induced by low concentrations of anaesthetic agents, and laboratory studies