Showing papers by "University of York published in 1988"

The structure of 2Zn pig insulin crystals at 1.5 A resolution.

Abstract: The paper describes the arrangement of the atoms within rhombohedral crystals of 2Zn pig insulin as seen in electron density maps calculated from X-ray data extending to 1.5 A (1 A = 10(-10) m = 10(-1) nm) at room temperature and refined to R = 0.153. The unit cell contains 2 zinc ions, 6 insulin molecules and about 3 x 283 water molecules. The atoms in the protein molecules appear well defined, 7 of the 102 side chains in the asymmetric unit have been assigned alternative disordered positions. The electron density over the water molecules has been interpreted in terms of 349 sites, 217 weighted 1.0, 126 weighted 0.5, 5 at 0.33 and 1 at 0.25 giving ca. 282 molecules. The positions and contacts of all the residues belonging to the two A and B chains of the asymmetric unit are shown first and then details of their arrangement in the two insulin molecules, 1 and 2, which are different. The formation from these molecules of a compact dimer and the further aggregation of three dimers to form a hexamer around two zinc ions, follows. It appears that in the packing of the hexamers in the crystal there are conflicting influences; too-close contacts between histidine B5 residues in neighbouring hexamers are probably responsible for movements of atoms at the beginning of the A chain of one of the two molecules of the dimer that initiate movements in other parts, particularly near the end of the B chain. At every stage of the building of the protein structure, residues to chains of definite conformation, molecules, dimers, hexamers and crystals, we can trace the effect of the packing of like groups to like, aliphatic groups together, aromatic groups together, hydrogen-bonded structures, positive and negative ions. Between the protein molecules, the water is distributed in cavities and channels that are continuous throughout the crystals. More than half the water molecules appear directly hydrogen bonded to protein atoms. These are generally in contact with other water molecules in chains and rings of increasing disorder, corresponding with their movement through the crystals. Within the established crystal structure we survey next the distribution of hydrogen bonds within the protein molecules and between water and protein and water and water; all but eight of the active atoms in the protein form at least one hydrogen bond.(ABSTRACT TRUNCATED AT 400 WORDS)

Misspecification Tests in Econometrics: The Lagrange Multiplier Principle and Other Approaches

Abstract: Misspecification tests play an important role in detecting unreliable and inadequate economic models. This book brings together many results from the growing literature in econometrics on misspecification testing. It provides theoretical analyses and convenient methods for application. The main emphasis is on the Lagrange multiplier principle, which provides considerable unification, although several other approaches are also considered. The author also examines general checks for model adequacy that do not involve formulation of an alternative hypothesis. General and specific tests are discussed in the context of multiple regression models, systems of simultaneous equations, and models with qualitative or limited dependent variables.

Emotionally focused therapy for couples

Abstract: This book demonstrates the power of emotional experience in relationships and how this power can be used to reconstruct intimate bonds. In emotionally focused couples therapy, intrapsychic and interpersonal perspectives are combined; interactional positions are assumed to be maintained by strong, primary, emotional responses and by the way interactions are structured and organized. Hence, the goal of emotionally focused therapy is to enable a couple to change the habitual positions they assume in relation to each other and to change the way each partner experiences the relationship.

The formation and function of oviduct fluid.

Abstract: Gabriele Fallopius (1523-1562) is credited with the first correct anatomical description of the oviduct, which he termed the "tuba uteri" after its resemblance to a brass musical instrument. Nowadays the terms 'oviduct', 'Fallopian tube', 'uterine tube' and 'tube' tend to be used interchangeably. In this review, the term 'oviduct' will be used to refer to the mammal generally, the term 'Fallopian tube' to the human exclusively. The oviduct is a muscular tube with a mucous lining. However, its gross anatomy differs considerably between species, notably in the degree of coiling. It is usually divided into 4 regions; the infundibulum, fringed by fimbriae and opening via the tuba1 ostium into the peritoneal cavity, the ampulla, the isthmus and the uterotubal junction. Some authors term the infundibulum and fimbriae the preampulla; the uterotubal junction is also known as the intramural or interstitial portion. For most of its length, the oviduct has two muscle coats, an external longitudinal and an internal circular coat. The mucosa is thrown into folds, also known as 'rugae' or 'plicae'. The proportions of muscle and mucosa vary along the length of the oviduct. The best-characterized species in this respect are the cow and the rabbit (El-Banna & Hafez, 1970; Leese, 1983), in both of which there is a gradual decline in the proportion of mucosa, the degree of mucosal folding, and the surface area of the lumen, and an increase in the proportion of muscle, as one proceeds from the infundibulum to the uterotubal junction.

Complainable Matters: The Use of Idiomatic Expressions in Making Complaints

Abstract: Idiomatic, proverbial, and other figurative expressions are quite frequently employed by speakers in ordinary talk. Our analysis of idioms in naturally occurring conversations reveals that they are used, not randomly, but most notably when one speaker is complaining to another. In this sequential environment the particularly egregious character of the matter being complained about is portrayed through an idiom. In view of the role complaints play in casting private troubles or anxieties into the public domain, it is significant that typically a complaint is formulated idiomatically at a point where there is some conflict or lack of alignment between complainant and recipient. Thus, idioms are introduced in "inauspicious environments," where, up until then, recipients have withheld sympathizing or affiliating with a complainant. Idioms have a special robustness which lends them the function of summarizing the complaint in such a way as to enhance its legitimacy, and simultaneously to bring the complaint to a close.

Correlation of DNA adduct levels in human lung with cigarette smoking

Abstract: Lung cancer is the most common cancer in men in the United Kingdom and the second most common in women, accounting for between 25 and 40% of all cancer deaths1,2 Cigarette smoking is widely accepted as the major cause of lung cancer and linear relationships have been established between the number of cigarettes smoked and lung cancer risk3. Although approximately 50 carcinogenic chemicals have been identified in cigarette smoke4, a causal link between specific compounds and lung cancer has yet to be made. Studies on cigarette smokers' urine5,6, blood7–11 and placenta12 have provided indications of carcinogen exposure, and although the presence of covalently-bound adducts in human DNA provides evidence of exposure to carcinogens12–14, there have been no reports of systematic studies on the levels of DNA adducts in human lung. We report here, using the 32P-post-labelling technique15,16, that cigarette smokers have higher adduct levels than non-smokers, that there is a linear relationship between adduct levels and daily or lifetime cigarette consumption, and that people who have given up smoking for at least five years have adduct levels similar to those of non-smokers.

Hyperactive Boys Almost Grown Up: III. Methylphenidate Effects on Ultimate Height

Abstract: • The height of young adults who were treated with methylphenidate hydrochloride in childhood because of hyperactivity (average daily dose, 45 mg; duration of treatment, six months to five years) was studied. There was no significant difference in height between the treated patients (n =61) and controls (n =99); both groups were at the national US norm in stature. The findings indicated that methylphenidate therapy does not compromise final height, even when it has an adverse impact on children's growth rate during the active treatment phase. A compensatory growth rate, or growth rebound, appears to occur following discontinuation of stimulant therapy.

Species number, species abundance and body length relationships of arboreal beetles in Bornean lowland rain forest trees

Abstract: . 1The relationships between number of species, abundance per species, and body length are examined for 859 species of beetles in samples of arthropods collected from ten Bornean lowland forest trees by insecticide fogging. Similar relationships are examined for different feeding guilds of these beetles, and for those beetles from different species of trees. 2The data are used to construct four interrelated graphs, namely species: abundance, species: body length, population abundance: body length and total number of individuals: body length distributions. 3In contrast to a number of previous studies, no consistent linear relationship between population density and body length was found for the Bornean beetles and it is suggested that, as in birds, the added dispersal ability of flight reduces critical population densities necessary for persistence in small species. Previous relationships between body weight and population abundance may also be artefacts of the way in which data were gathered. 4Despite large samples, we failed to locate the mode in plots of the number of species in each abundance category (species: abundance distribution). 5Species: body length and total number of individuals: body length plots were similar to those found in previous studies, although using data for Coleoptera alone may have produced a steeper decline in the total number of individuals as body size increases than is apparent in samples of all arthropods. 6We present the first three-dimensional graph relating numbers of species, body lengths and population abundances. The surface of this three-dimensional relationship is relatively simple.

Taurine in development.

Abstract: Taurine is a ubiquitous dietary constituent of most mammals and is present in especially high concentrations in the tissues of developing mammals. Research to date indicates that taurine plays an important role in the development of the nervous system and the process of migration in particular. It is speculated that taurine uptake and release, in conjunction with glutamate uptake and release, may represent one form of communication between neurons and glial cells. The need of taurine by the body is emphasized by the ability of the kidney to curtail taurine excretion to conserve taurine in the face of a low dietary taurine intake. The evidence for a special role of taurine in development is considered and discussed.

Patterns in the distribution and abundance of insect populations

Abstract: A central problem in ecology is to identify and understand patterns in the distribution and abundance of species1,2. Here, we analyse six patterns for insect populations and explore their inter-relationships. For moths, aphids, carabid beetles, and insects feeding on bracken, we examine links between local population abundance, local population variability, regional distribution, and body size. We show that population characteristics are correlated both theoretically and empirically. Widespread species are generally locally abundant, and have populations that fluctuate more than scarce, geographically restricted species. Predicted effects of body size are less well supported, although common, widespread, widely fluctuating species tend to be small.

MMPI, Rorschach, and WAIS: A Meta-Analytic Comparison of Reliability, Stability, and Validity

Abstract: We estimated the average reliability, stability, and validity of the Minnesota Multiphasic Personality Inventory (MMPI), Rorschach Inkblot Test, and Wechsler Adult Intelligence Scale (WAIS) from articles published in the Journal of Personality Assessment and the Journal of Clinical Psychology betwee

Relating process to outcome in marital therapy

Abstract: Although there are a growing number of outcome research studies in marital therapy, there is a complete absence of research on change processes, and how such processes relate to outcome. This study attempts to analyze the process of change in the “best” sessions of Emotionally Focused Marital Therapy (EFT) (Greenberg & Johnson, 1986). Client performance in therapy was rated on depth of experiencing and the quality of interpersonal interactions. The occurrence of particular change events arising from the theoretical principles of EFT was also noted. Results confirmed hypotheses that higher levels of experiencing and more autonomous and affiliative interactions characterized “best” sessions of couples who were successful in therapy. The implications for treatment are discussed.

The role of glucose and pyruvate transport in regulating nutrient utilization by preimplantation mouse embryos

Abstract: Preimplantation mouse embryos utilize pyruvate preferentially during the early cleavage stages before switching to glucose at around the time of compaction. This switch in substrate preference has been studied using a non-invasive ultramicrofluorometric analytical technique on single mouse embryos. On the basis of transport kinetic studies and inhibition by phloretin, cytochalasin B and sugar analogues, a component of glucose uptake by mouse blastocysts was found to be mediated by facilitated diffusion. The Jmax and Kt of this facilitated component were 3.53 pmol embryo-1 h-1 and 0.14 mM, respectively. At physiological concentrations of glucose, the facilitated component accounts for around 75% of glucose uptake. Glucose uptake by blastocysts was found to be insensitive to insulin, added at a range of concentrations. There was no evidence for glucose active transport. The carrier-mediated component of glucose entry was detectable from the 2-cell stage onwards. Pyruvate uptake was also mediated by a carrier throughout development. In the absence of glucose in the incubation medium, the characteristic decline in pyruvate uptake does not occur. The data are consistent with a role for embryonic cell transport in regulating glucose utilization prior to compaction, but do not exclude the involvement of metabolic factors, such as the allosteric regulation of the enzymes hexokinase and phosphofructokinase.

Normal writing processes and peripheral acquired dysgraphias

Abstract: The cognitive operations involved in writing may be divided for convenience into central and peripheral processes. Central processes include semantic, syntactic and other sentence-level operations, along with those processes responsible for either retrieving from memory the spelling of a familiar word or assembling from sound a plausible spelling for an unfamiliar word or nonword. The end-product of these central processes is an abstract graphemic representation of words as letter strings. Peripheral writing processes translate that abstract graphemic representation into a range of possible output modes, including handwriting, typing, and spelling aloud. A model of peripheral writing processes is presented, concentrating on the processes responsible for creating handwritten output. A number of different peripheral acquired dysgraphias including mirror writing are then reviewed and interpreted in terms of impairment at different levels in the conversion of abstract graphemes into written letters a...

Work and family precursors of burnout in teachers: Sex differences

Abstract: This paper examines factors contributing to burnout in women and men teachers. Results indicated that men were significantly higher than women on one of the Maslach burnout subscales—depersonalization. Additional results showed that women experienced significantly more depression, headaches, and role conflict than their male counterparts. Multiple regression results indicated that 47% of the variation in burnout was accounted for by a model of burnout that included role conflict, marital satisfaction, work sources of stress, and social support in women. But in men, the main contributor to burnout was sources of stress including doubts about competence and problems with students. The results are discussed from a gender role perspective that takes account of the differential implications of gender roles for women and men.

Nonstandard Analysis and its Applications

Abstract: This textbook is an introduction to non-standard analysis and to its many applications. Non standard analysis (NSA) is a subject of great research interest both in its own right and as a tool for answering questions in subjects such as functional analysis, probability, mathematical physics and topology. The book arises from a conference held in July 1986 at the University of Hull which was designed to provide both an introduction to the subject through introductory lectures, and surveys of the state of research. The first part of the book is devoted to the introductory lectures and the second part consists of presentations of applications of NSA to dynamical systems, topology, automata and orderings on words, the non- linear Boltzmann equation and integration on non-standard hulls of vector lattices. One of the book's attractions is that a standard notation is used throughout so the underlying theory is easily applied in a number of different settings. Consequently this book will be ideal for graduate students and research mathematicians coming to the subject for the first time and it will provide an attractive and stimulating account of the subject.

Introduction to Biostatistics, 2nd Edn.

Abstract: Introduction to Biostatistics, 2nd edn. By R. R. Sokal and F. J. Rohlf. ISBN 0 7167 1805 7. Freeman. £37.95.

Sensory dominance in infants. II: Ten-month-old infants' response to auditory-visual compounds

Abstract: A series of studies was conducted with 10-month-old infants in which their response to temporally modulated auditory-visual compounds was examined. The general procedure consisted of first habituating the infants to a compound stimulus (consisting of a flashing checkerboard and a pulsing sound) and then testing their response to it by presenting a series of trials where either one or two temporal attributes of the visual, the auditory, or of both components were changed. When the auditory and visual components were temporally identical, during the habituation phase, the infants only encoded the temporal attributes of the auditory component. When the two components were temporally distinct, or when they were identical but when multiple discriminative cues were available, the infants encoded the temporal aspects of both the auditory and the visual components. When the information context was made more complex, the infants' performance deteriorated, but when the salience of the visual component was increased the infants' performance improved. In sum, although the auditory modality can dominate the visual modality at 10 months of age, the visual modality can process temporal information when the temporal relationship of the information in the two modalities is distinct. Most of the research on sensory/perceptual development in human infants has been concerned with the functional characteristics of single sensory modalities. Only quite recently have investigators begun to examine the way that sensory systems interact with one another during early development (Rose & Ruff, 1987). Most of the research on intersensory interaction has, however, been concerned with the detection of intersensory equivalence. The implicit assumption of all this work has been that the sensory systems operate on an equal footing. Given that the structural and functional aspects of the different sensory systems develop asynchronously (Bronson, 1982; Gottlieb, 1971; Kasatkin, 1972; Volokhov, 1968), however, the possibility that sensory dominance hierarchies operate during early development and that their nature may change during this time must be considered seriously. In a companion article, Lewkowicz (1988; see pp. 155-171, this issue) reported on a set of studies that investigated 6-monthold infants' processing of temporally based auditory-visual compounds. The general purpose of those studies was to investigate the relationship of the auditory and visual modalities when information from each of them competed for the infant's attention. Specifically, these studies systematically determined whether responsiveness to information in one sensory modality

Coordinated assembly of multisubunit proteins: oligomerization of bacterial enterotoxins in vivo and in vitro.

Abstract: In this paper we study the assembly, in vivo and in vitro, of a family of hexameric, heat-labile enterotoxins produced by diarrheagenic bacteria. The toxins, which consist of an A subunit and five B subunits, are assembled by a highly coordinated process that ensures secretion of the holotoxin complex. We show that (i) oxidation of cysteine residues in the B subunits is a prerequisite step for in vivo formation of B-subunit pentamers, (ii) reduction of dissociated B subunits in vitro abolishes their ability to reassemble, (iii) the kinetics of B-pentamer assembly in vivo can be mimicked under defined conditions in vitro, (iv) A subunits cannot associate with fully assembled B pentamers in vitro, and (v) A subunits cause an approximately 3-fold acceleration in the rate of B-subunit pentamerization in vivo, implying that A subunits play a coordinating role in the pathway of holotoxin assembly. The last finding is likely to be of general significance, since it provides a mechanism for preferentially excluding or favoring certain intermediates in the assembly of multisubunit proteins.

On the question of mechanism in phototherapy for seasonal affective disorder: considerations of clinical efficacy and epidemiology.

Abstract: or months to exert their effects, and the clinical results are often not so dramatically straightforward. We may guess that bright light to the retina, in light-starved patients suffering from seasonal affective disorder (SAD), excites central responses through direct connections to the hypothalamus, where aberrant vegetative sleep and feeding patterns can be brought under control and the mood can be elevated. Indeed, given preliminary evidence that antidepressant medications may change the retina’s sensitivity to light (Terman, Rem6, and Wirz-Justice, in preparation), the primary locus may be peripheral. But we are far from fleshing out such scenarios with convincing data, and there

The use of benomyl to control infection by vesicular–arbuscular mycorrhizal fungi

Abstract: SUMMARY The effect of the fungicide, benomyl, on vesicular arbuscular (VA) mycorrhizal infection and phosphorus uptake was studied in two pot experiments, using pea Pisum sativum L., mustard Sinapis alba L. and red clover Trifolium pratense L. Benomyl was either incorporated into the soil or sprayed on to the surface of the pot. Benomyl had no effect on concentrations of water-soluble P in soil but reduced VA mycorrhizal infection and P inflow in pea. Mustard plants were uninfected even in untreated pots and benomyl had no effect on P inflow in mustard. In clover, there was a positive correlation between shoot P concentration and percentage of root length infected with VA mycorrhizal fungi. Copper, zinc and manganese concentrations in clover shoots were affected by benomyl but this may not have been related to mycorrhizal infection. Benomyl is recommended as a treatment to control VA mycorrhizal infection, with many fewer undesirable consquences than result from soil sterilization.