Showing papers by "University of London published in 1986"

Anxiolytic and anxiogenic drug effects on exploratory activity in an elevated plus-maze: a novel test of anxiety in the rat

Abstract: The current studies further investigated the effects, in animal models of anxiety, of novel putative anxiolytic and anxiogenic compounds believed to induce their effects by actions at the GABA-benzodiazepine receptor complex. It was expected that the results would also provide further validation for a novel test of anxiety based on the ratio of open to closed arm entries in an elevated plus maze in the rat. The novel putative anxiolytics CL 218,872 (10–20 mg/kg) and tracazolate (5 mg/kg) significantly elevated the percentage of time spent on the open arms of an elevated plus-maze, consistent with their anxiolytic activity in several other animal tests. Also consistent with results from other animal tests, no anxiolytic activity was observed for the phenylquinoline PK 8165 (10–25 mg/kg), the 3,4-benzodiazepine tofisopam (25–50 mg/kg), or buspirone (0.5–20 mg/kg). The benzodiazepine receptor inverse agonists FG 7142 (1–5 mg/kg) and CGS 8216 (3–10 mg/kg) had anxiogenic activity in this test, as did the atypical benzodiazepine Ro 5-4864 (1–5 mg/kg). Interestingly, however, the benzodiazepine receptor antagonists Ro 15-1788 (10–20 mg/kg) and ZK 93426 (5–10 mg/kg) had no anxiogenic activity in this test.

Multilevel mixed linear model analysis using iterative generalized least squares

Abstract: SUMMARY Models for the analysis of hierarchically structured data are discussed. An iterative generalized least squares estimation procedure is given and shown to be equivalent to maximum likelihood in the normal case. There is a discussion of applications to complex surveys, longitudinal data, and estimation in multivariate models with missing responses. An example is given using educational data.

The autistic child's appraisal of expressions of emotion

Abstract: Groups of MA-matched autistic, normal and non-autistic retarded children were tested for their ability to choose drawn and photographed facial expressions of emotion to "go with" a person videotaped in gestures, vocalizations and contexts indicative of four emotional states. Although both autistic and control subjects were adept in choosing drawings of non-personal objects to correspond with videotaped cues, the autistic children were markedly impaired in selecting the appropriate faces for the videotaped expressions and contexts. Within the autistic group, the children's performance in this task of emotion recognition was related to MA. It is suggested that autistic children have difficulty in recognizing how different expressions of particular emotions are associated with each other, and that this might contribute to their failure to understand the emotional states of other people.

The British Nationality Act as a logic program

Abstract: The formalization of legislation and the development of computer systems to assist with legal problem solving provide a rich domain for developing and testing artificial-intelligence technology.

A preliminary study of the transmission dynamics of the human immunodeficiency virus (HIV), the causative agent of AIDS.

Abstract: The paper describes some preliminary attempts to formulate simple mathematical models of the transmission dynamics of HIV infection in homosexual communities. In conjunction with a survey of the available epidemiological data on HIV infection and the incidence of AIDS, the models are used to assess how various processes influence the course of the initial epidemic following the introduction of the virus. Models of the early stages of viral spread provide crude methods for estimating the basic reproductive rate of the virus, given a knowledge of the incubation period of the disease (AIDS) and the initial doubling time of the epidemic. More complex models are formulated to assess the influence of variation in the incubation period and heterogeneity in sexual activity. The latter factor is shown to have a major effect on the predicted pattern of the epidemic; high levels of heterogeneity decrease its magnitude. Areas of biological uncertainty, future research needs, and public health implications are discussed.

The GRISS: A Psychometric Instrument for the Assessment of Sexual Dysfunction

Abstract: The Golombok Rust Inventory of Sexual Satisfaction (GRISS) is a short 28-item questionnaire for assessing the existence and severity of sexual problems. The design, construction, and item analysis of the GRISS are described. The two separate male and female scales are shown to have high split-half reliabilities of 0.94 for women and 0.87 for men. Validation of change scores in the GRISS on 30 clinical couples, before and after therapy, showed correlations with therapists' blind ratings of 0.54 (p <0.001)for men and 0.43 (p <0.01)for women. Discriminatory validity between clinical (n =69)and nonclinical (n =59)groups was r =0.63 for women and r =0.37 for men. The 12 subscales of impotence, premature ejaculation, anorgasmia, vaginismus, noncommunication, infrequency, male and female avoidance, male and female nonsensuality, and male and female dissatisfaction are also shown to have good reliability and validity.

The phytoalexin response: elicitation, signalling and control of host gene expression

Abstract: Summary 1. Induced resistance of plants to incompatible races of their microbial pathogens is often characterized by rapid cell death (the hypersensitive response) and the accumulation of low-Mr antimicrobial compounds termed phytoalexins. There is much indirect evidence to support a major role for phytoalexin induction as an event determining host resistance, and genetical analysis of race-specific pathogen-host interactions predicts that induced resistance occurs via interaction between a pathogen avirulence gene product and a host resistance gene product. Elicitors (inducing agents) of phytoalexin accumulation are possible candidates for the active products directly or indirectly resulting from the expression of microbial avirulence genes. The present review considers the process of phytoalexin induction, at the molecular level, from the fungal elicitor to the early changes in host gene expression associated with its action. 2. A number of microbial polysaccharides, glycoproteins, pectic enzymes, peptides and fatty acids have potent elicitor activity. 3. The results of studies on the purification and characterization of microbial elicitors depend on the nature of the bioassay used. Methods for elicitor extraction may lead to artifacts or loss of race specificity. 4. Elicitors isolated from plant pathogens may be race-specific or race-non-specific. In cases where only race-non-specific elicitors can be shown, race-specific induction of phytoalexins may result from the action of enhancer or suppressor molecules. Fungal glucans have been proposed as candidates to act in both these roles. 5. Molecular genetic approaches to the identification of phytopathogenic bacterial avirulence genes may help to prove or disprove the role of elicitors of the phytoalexin response as agents responsible for the induction of host resistance. Similar analyses, involving genetic transformation, should soon be possible for phytopathogenic fungi. 6. Studies on the nature of host receptors for microbial elicitors are still in their infancy. Such receptors are probably localized in the plant plasma membrane, and elicitation results in often striking changes in host membrane properties. 7. Cyclic 3′,5′-adenosine monophosphate and polyamines do not appear to act in plants as intracellular transducers of the phytoalexin response. Interest is now being shown in a possible role for calcium in intracellular signalling. 8. Plant cells contain endogenous elicitor molecules whose synthesis or release may play a role in the intercellular transmission of the phytoalexin response. The main candidates for endogenous elicitors are pectic fragments of the host cell wall, although no direct evidence for their involvement in plant-pathogen interactions is available. Pectic fragments may act as synergists in parallel with, rather than as couplers in series with, microbial elicitors. The role of ethylene as a response coupler for induced resistance phenomena is difficult to assess. 9. Some elicitors may themselves move to the host cell nucleus, although whether this is their effective site of action remains unclear. 10. Induction of the phytoalexin response is associated with specific changes in host gene expression related to the selective induction of new mRNA species and enzyme activities. 11. Progress is now being made in the characterization of enzymes specific for phytoalexin biosynthesis. Enzyme induction and/or infection appears to involve rapid modulation of gene transcription, although some post-translational events may also be involved in determining induction patterns. 12. Work is now commencing on the sequencing of the genes encoding elicitor-inducible enzymes. Multigene families have been identified for phenylalanine ammonia-lyase and chalcone synthase. 13. Phytoalexin accumulation may be accompanied by the rapid induction of ethylene biosynthesis and the expression of genes encoding activities involved in the synthesis of hydroxyproline-rich glycoproteins. 14. Pectic endogenous elicitors of phytoalexin accumulation are also active as inducers of systemic proteinase inhibitor synthesis in some solanaceous species. 15. Results of studies on the mechanisms of signal transmission and differential gene expression in relation to active defence reactions should be of relevance to many other aspects of the plant's response to environmental stimuli at the physiological, biochemical and molecular genetical levels.

The autistic child's appraisal of expressions of emotion: a further study.

Abstract: Autistic and matched non-autistic retarded children were selected for their ability to recognize the correspondence between schematic drawings and videotaped scenes involving people. The subjects of both groups were able to choose schematic drawings of gestures for a person's gestures of emotion enacted on videotape. However, the autistic children were significantly impaired in choosing which of the drawings of gestures should ‘go with’ videotaped vocalizations and facial expressions characteristic of four emotional states. The results were found to be consistent with results from a previous, related study in which the same subjects had chosen drawn or photographed faces to indicate their judgements of the same videotapes of emotional expression. It is suggested that these findings reflect an important aspect of autistic children's social disability.

Optics of Fractal Clusters Such as Smoke

Abstract: Scalar or vector light of wavelength 2~/k strikes N small refracting and absorbing spherules, each of radius a, which have coagulated into a sparse random cluster with fractal dimension D (for smok...

Intrinsic actions of the benzodiazepine receptor antagonist Ro 15-1788.

Abstract: The imidazodiazepine Ro 15-1788 is a benzodiazepine receptor antagonist that was initially reported to be lacking in intrinsic activity in a variety of test situations in which benzodiazepine-like effects can be identified. However, many recent studies have shown that this compound does indeed have intrinsic activity in a variety of behavioural, neurological, electrophysiological and biochemical preparations in both animals and man. The purpose of the present review is firstly to describe these intrinsic actions, and secondly to consider to what extent these intrinsic actions of Ro 15-1788 have implications for current concepts of the functioning of the benzodiazepine receptor.

Two polyphosphatidylinositide metabolites control two K + currents in a neuronal cell

Abstract: Hydrolysis of the membrane phospholipid phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) produces two prospective intracellular messengers: inositol 1,4,5-trisphosphate (InsP3), which releases Ca2+ from intracellular stores; and diacylglycerol (DG), which activates protein kinase C. Here we show how the formation of these two substances triggered by one external messenger, bradykinin, leads to the appearance of two different sequential membrane conductance changes in the neurone-like NG108-15 neuroblastoma-glioma hybrid cell line. In these cells bradykinin rapidly hydrolyses PtdIns(4,5)P2 to InsP3 and DG, raises intracellular Ca2+ and hyperpolarizes then depolarizes the cell membrane. By voltage-clamp recording we show that the hyperpolarization results from the activation pharmacologically-identifiable species of Ca2+-dependent K+ current. This is also activated by intracellular injections of Ca2+ or InsP3 so may be attributed to the formation and action of InsP3. The subsequent depolarization results primarily from the inhibition of a different, voltage-dependent K+ current, the M-current that is also inhibited by DG activators. Hence we describe for the first time a dual, time-dependent role for these two intracellular messengers in the control of neuronal signalling by a peptide.

Cohort Study Analysis with a FORTRAN Computer Program

Abstract: We describe the analysis of cohort study data with a standard FORTRAN program which should run on most computers. It provides a summary measure of the mortality (or incidence) rate ratio between the study cohort and some standard population, based either on person-years at risk or on proportional mortality, and adjusted for age, sex and calendar period; a test of the statistical significance of the ratio; and a set of observed death rates in the study cohort. Results may also be produced in a form suitable for use with GLIM. The analysis may be subdivided into a range of time intervals since each subject was first exposed to risk. The program provides for movement of subjects between different 'level-of-exposure' subgroups within the cohort, and for various methods of censoring. It allows considerable flexibility in data management, and is available with complete documentation and a worked example. The program should enable epidemiologists with little computing experience to carry out formal analysis of cohort studies.

Social constructionism and the development of medical sociology

Abstract: This paper offers a review of recent approaches in the ‘social constructionism’ of medical knowledge. It argues that ‘constructionist’ propositions offer a bold attempt to resolve some of the problems in earlier formulations of the sociology of medical knowledge, particularly those of Eliot Freidson. However, the paper goes on to argue that social constructionism has failed to tackle the inherent relativism in its stance and that it frequently rests on contradictory intellectual and value premises. The paper concludes that both policy considerations and theoretical consistency require a critical appraisal of social contructionism and its future role in medical sociology.

Monitoring the grasslands of the Sahel 1984-1985

Abstract: Normalized difference vegetation index data obtained from polar-orbiting meteorological satellites were used to compare the growing or rainy seasons of 1984 and 1985 for the Sahelian zone of Africa. A substantial difference was found between these two years, with 1985 generally having higher normalized difference vegetation index values indicating higher levels of primary production in 1985 than in 1984. 1 km data were compared for Senegal, Mali, Niger and Sudan, and 7 km data were compared for sub-Saharan Africa. The qualitative comparison of these data suggests the use of similar data to assist in centralized monitoring of rangeland conditions, to identify areas of deficiencies in primary production and provide synoptic information in support of regional drought monitoring.

Lessons from community participation in health programmes

Abstract: A review of close to 200 case studies of health care programs in developing countries that have emphasized community participation suggests 4 major lessons. 1st it is not possible or even useful to have a universally acceptable definition of community participation. Planners should view community participation as being in a dynamic rather than a static state and should remain flexible as people and objectives change. 2nd it is not possible to build broad self-sustaining community participation through health services activities alone. Wide participation develops as part of a process that addresses a range of community needs. 3rd it is not possible to consider community participation outside of a political context. Any program that seeks to address the issue of community participation must also deal with the issues of power and control. 4th it is not realistic to propose a model for managing community participation in health programs. Planners must be prepared to surrender their dominant role in programs and allow communities to decide the ways in which programs will develop. The answers to the questions of the rationale for community participation the identity of the participants and the ways in which people participate can help planners and agencies to clarify and implement program goals. These answers can be viewed as falling along a continuum. Programs at one extreme are mainly concerned with health services management and view community participation as a program component while programs at the other extreme focus on community development activities and give priority to community decision making at the cost of efficiency.

Dissipation in a fundamental model of quantum optical resonance

Abstract: The fully quantum-electrodynamical model of a two-level atom interacting with a single-cavity mode predicts an atomic evolution whose form is dictated by the discrete nature of the field energy and its statistical distribution. We demonstrate that the revivals of atomic excitation which are the signature of the quantum nature of the evolution are strongly affected by field dissipation even when the damping hardly affects the underlying Rabi oscillations.

Satellite remote sensing of rangelands in Botswana II. NOAA AVHRR and herbaceous vegetation

Abstract: The relation between the normalized difference vegetation index (NDVI) and the herbaceous vegetation in Tamasane, Shakwe, and Masama in eastern Botswana is studied using 1983-1984 AVHRR data. The procedures for Landsat MSS interpolation of ground measurements and the data processing of the AVHRR data are described. The temporal sequence AVHRR global-area coverage (GAC) composite NDVI is examined. The AVHRR GAC composite NDVI and biomass and Landsat MSS interpolations of field measurements are analyzed and compared.

Lung Mechanics in Disease

Abstract: The sections in this article are: 1 Obstructive Lung Disease 1.1 Chronic Obstructive Pulmonary Disease 1.2 Asthma 1.3 Upper Airway Obstruction 2 Restrictive Lung Disease 2.1 Intrapulmonary Disease 2.2 Extrapulmonary Disease

Human papillomavirus types 16 and 18 in carcinomas of the penis from Brazil.

Abstract: Human papillomavirus (HPV) type-16 DNA sequences were found in 26/53 (49%) and HPV type-18 in 5/53 (9%) of penile cancers. In only one specimen was HPV18 found on its own. HPV16 sequences were integrated into the host cell chromosomes although some monomeric and oligomeric free forms of DNA were detected in a few tissues. HPV18 was, as far as detectable, free and unintegrated in all tissues tested. HPV16 DNA was also detected in 40% of cases of carcinoma of the cervix in 19 women from the same social groups as the males. The viral DNA in the female cases was a mixture of integrated and free forms. The DNA binding protein (ICSP 11/12) of herpes simplex type 2 (HSV2) was not detected in 10 penile cancers tested with a monoclonal antibody.

Neutralizing (54K) and non-neutralizing (54K and 48K) monoclonal antibodies against structural and non-structural yellow fever virus proteins confer immunity in mice.

Abstract: Summary The capacity of monoclonal antibodies to protect mice passively against yellow fever (YF) virus infection was investigated. Both neutralizing (54K-specific) and non-neutralizing (54K- and 48K-specific) antibodies protected mice against challenge with the RMP substrain of YF virus. Average survival times of mice inoculated intracerebrally with a standard lethal dose of YF virus differed according to the strain used: thus mice inoculated with the most neurovirulent viruses, FNV and Asibi, survived for 6.50 and 7.65 days respectively, and those with RMP virus survived for 15.75 days. The capacity of antibodies to protect mice passively against virus challenge was directly related to virus neurovirulence. Possible mechanisms and the significance of protection by antibodies against non-structural proteins that do not mediate neutralization, are discussed.

Relationships between larval density, adult size and egg production in the cowpea seed beetle, Callosobruchus maculatus

Abstract: 1 The eggs of the cowpea seed bettle Callosobruchus maculatus (Fab) are attached to cowpeas On hatching, the larvae penetrate the testa and remain in the seed until development is complete and adult eclosion has occurred The adults do not need to feed and were not allowed to do so 2 Strains from Brazil and Nigeria can produce more than twelve adults from a seed bearing numerous eggs, whereas a strain from the Yemen Republic rarely produced more than three 3 In all three strains the mean weight of the adults produced from a single cowpea declined with increasing initial larval density in the seed 4 Egg production by females is positively correlated with their weight at the time of mating, shortly after emergence 5 Lifetime egg production by females of the Brazilian and Nigerian strains was lower if they came from cowpeas with higher initial larval densities No such relationship could be demonstrated in the Yemen strain 6 The fecundity of one generation of these beetles, at least in some geographical strains, is significantly affected by the number of larvae entering the hosts in which the adults of that generation have developed