Showing papers by "University of London published in 1992"
TL;DR: Heuristic suggestions for variance imputation based on partial variance information are provided and a key idea is to use separate sources of incomplete information to help choose a better variance estimate.
1,092 citations
TL;DR: This study screened 41 18-month-old toddlers who were at high genetic risk for developing autism, and 50 randomly selected 18- month-olds, using a new instrument, the CHAT, administered by GPs or health visitors, to establish if detection of autism was possible at 18 months of age.
Abstract: Autism is currently detected only at about three years of age. This study aimed to establish if detection of autism was possible at 18 months of age. We screened 41 18-month-old toddlers who were at high genetic risk for developing autism, and 50 randomly selected 18-month-olds, using a new instrument, the CHAT, administered by GPs or health visitors. More than 80% of the randomly selected 18-month-old toddlers passed on all items, and none failed on more than one of pretend play, protodeclarative pointing, joint-attention, social interest, and social play. Four children in the high-risk group failed on two or more of these five key types of behaviour. At follow-up at 30 months of age, the 87 children who had passed four or more of these key types of behaviour at 18 months of age had continued to develop normally. The four toddlers who had failed on two or more of these key types of behaviour at 18 months received a diagnosis of autism by 30 months.
869 citations
TL;DR: In this article, four major criticisms of the Costa and McCrae 5-factor model are discussed, including the lack of a nomological network or theoretical underpinning for the 5 factors, and the failure of providing a biological link between genetic causation and behavioural organization.
758 citations
TL;DR: The purification and properties of three key enzymes (glutathionylspermidine synthetases, trypanothione synthetase, and trypanothsione reductase) are discussed, and the catalytic mechanism, substrate-specificity, andThe three-dimensional structure of trypanOTHione reduCTase are compared to that of glutathione reductor.
Abstract: Trypanosomatids differ from all other organisms in their ability to conjugate the sulfur-containing tripeptide, glutathione, and the polyamine, spermidine, to form trypanothione [N1,N8-bis(glutathionyl)spermidine]. Together with the NADPH-dependent flavoprotein, trypanothione reductase, the dithiol form of trypanothione provides an intracellular reducing environment in these parasites, substituting for glutathione and glutathione reductase found in the mammalian host. Trypanothione and its related enzymes are involved in defense against damage by oxidants, certain heavy metals, and possibly xenobiotics. Trypanothione and its metabolic precursor, glutathionylspermidine, are also implicated in the modulation of spermidine levels during growth. Several existing trypanocidal drugs interact with the trypanothione system, suggesting that trypanothione metabolism may be a good target for the development of new drugs. The purification and properties of three key enzymes (glutathionylspermidine synthetase, trypanothione synthetase, and trypanothione reductase) are discussed, and the catalytic mechanism, substrate-specificity, and the three-dimensional structure of trypanothione reductase are compared to that of glutathione reductase.
737 citations
Book Chapter•
01 Jan 1992Abstract: Critical Theory and Management Studies - Mats Alvesson and Hugh Willmott An Introduction Disciplinary Power in the Modern Corporation - Stanley Deetz Critical Ethnography - John Forester On Fieldwork in a Habermasian Way The Organization of Pleasure - Gibson Burrell Technical, Practical and Critical O.R. - Past, Present and Future? - John Mingers Critical Theory and Accounting - Michael Power and Richard Laughlin Marketing Discourse and Practice - Glenn Morgan Towards a Critical Analysis Information Systems and Critical Theory - Kalle Lyytinen Personnel/Organization Psychology - Brian D Steffy and Andrew J Grimes A Critique of the Discipline Critical Social Science for Managers? Promising Perverse Possibilities - Walter R Nord and John M Jermier
733 citations
709 citations
TL;DR: It is found that whereas autistic children perform very poorly on tests of the concept, believes, they are at or near ceiling on comparable tasks that test understanding of pictorial representation, which supports the existence of a specialized cognitive mechanism, which subserves the development of folk psychological notions, and which is dissociably damaged in autism.
682 citations
TL;DR: The use of simple summary statistics for analysing repeated measurements in randomized clinical trials with two treatments supports the value of the compound symmetry assumption as a realistic simplification in quantitative planning of repeated measures trials.
Abstract: This paper explores the use of simple summary statistics for analysing repeated measurements in randomized clinical trials with two treatments. Quite often the data for each patient may be effectively summarized by a pre-treatment mean and a post-treatment mean. Analysis of covariance is the method of choice and its superiority over analysis of post-treatment means or analysis of mean changes is quantified, as regards both reduced variance and avoidance of bias, using a simple model for the covariance structure between time points. Quantitative consideration is also given to practical issues in the design of repeated measures studies: the merits of having more than one pre-treatment measurement are demonstrated, and methods for determining sample sizes in repeated measures designs are provided. Several examples from clinical trials are presented, and broad practical recommendations are made. The examples support the value of the compound symmetry assumption as a realistic simplification in quantitative planning of repeated measures trials. The analysis using summary statistics makes no such assumption. However, allowance in design for alternative non-equal correlation structures can and should be made when necessary.
607 citations
TL;DR: Hyperactive children were more concerned to reduce overall delay levels than either to maximize reward amount or immediacy, suggesting a maladaptive preference for the small reward under the trials constraint.
Abstract: Two experiments are reported in which hyperactive and control children repeatedly chose between small immediate and large delayed rewards. In experiment 1, the best choice option was manipulated by varying levels of delay after reward delivery. In experiment 2 it was manipulated by changing the economic constraint (10 minutes or 20 trials). Both groups were equally efficient at earning points under most conditions, but hyperactive children exhibited a maladaptive preference for the small reward under the trials constraint. The results suggest that hyperactive children were more concerned to reduce overall delay levels than either to maximize reward amount or immediacy.
542 citations
TL;DR: Both carnosol and carnosic acid stimulated DNA damage in the bleomycin assay but they scavenged hydroxyl radicals in the deoxyribose assay.
Abstract: 1. Carnosol and carnosic acid have been suggested to account for over 90% of the antioxidant properties of rosemary extract.2. Purified carnosol and carnosic acid are powerful inhibitors of lipid peroxidation in microsomal and liposomal systems, more effective than propyl gallate.3. Carnosol and carnosic acid are good scavengers of peroxyl radicals (CCl3O2) generated by pulse radiolysis, with calculated rate constants of 1–3 × 106M-1 S-1 and 2.7 × 107M-1 S-1 respectively.4. Carnosic acid reacted with HOCl in such a way as to protect the protein α1-antiproteinase against inactivation.5. Both carnosol and carnosic acid stimulated DNA damage in the bleomycin assay but they scavenged hydroxyl radicals in the deoxyribose assay. The calculated rate constants for reaction with ·OH in the deoxyribose system for carnosol and carnosic acid were 8.7 × 1010M-1 and 5.9 × 1010M-1 S-1 respectively.6. Carnosic acid appears to scavenge H2O2, but it could also act as a substrate for the peroxidase system.7. Carnosic acid a...
491 citations
TL;DR: Examination of patterns of hysterectomy in the Oxford‐Family Planning Association (Oxford‐FPA) study in relation to age, parity, social class and calendar period finds patterns are similar to previous studies.
TL;DR: The new and revised classification is compared with the previous version, the reasons for the changes are outlined, and reference is made to a number of newly characterized lesions that have been included.
Abstract: This article introduces the revised World Health Organization (WHO) classification of odontogenic tumors and jaw cysts and certain bone lesions that either are peculiar to the jaws or have distinctive features in that location. The new and revised classification is compared with the previous version, the reasons for the changes are outlined, and reference is made to a number of newly characterized lesions that have been included.
TL;DR: Serological studies on a group of 151 S. mansoni‐infected individuals resident in an endemic areain Machakos District, Kenya found antibody levels against various antigens before treatment were related to intensity of previous infections; antibodies in blood samples taken 6 months after treatment wererelated to cumulative reinfection rates over the following 30 months.
Abstract: Previous studies in school children have demonstrated the slow development with age of resistance to reinfection after chemotherapy of Schistosoma mansoni infections, and have indicated that inappropriate ("blocking") antibody responses prevent the expression of immunity in young children. The present study was designed to investigate further the nature of the protective responses, by serological studies on a group of 151 S. mansoni-infected individuals resident in an endemic area in Machakos District, Kenya. Antibody levels against various antigens in blood samples before treatment were related to intensity of previous infections; antibodies in blood samples taken 6 months after treatment were related to cumulative reinfection rates over the following 30 months. IgE against an adult-worm antigen preparation correlated positively with age and negatively with reinfection. In contrast, IgE antibodies against other life-cycle stages showed either no relationship or the reverse correlation. Furthermore, antibodies of other isotypes against adult-worm antigens showed no correlations with reinfection. The correlation with IgE could be demonstrated for different preparations of adult worms, including a periodate-treated preparation presumptively depleted of carbohydrate epitopes. For both the intact and the periodate-treated preparations, multiple regression analysis of the results for children less than or equal to 16 years old demonstrated an IgE effect after allowing for age, although this effect was not observed in a previously studied group of school children. Western blot analysis of the adult-worm preparation revealed a limited set of antigens recognized by IgE, among which an antigen of 22 kDa was prominent. The qualitative presence of IgE against this antigen could also be shown to be related to a lack of subsequent reinfection.
Journal Article•
TL;DR: The test was shown to be sensitive, and specificity was demonstrated using DNA derived from a panel of Gram-negative pathogens, and there was no detectable difference between B. melitensis and B. abortus.
Abstract: Suitable reaction conditions and oligonucleotide primers were sought for the detection of Brucella melitensis and Brucella abortus by the polymerase chain reaction. Primers were chosen from within the coding sequence of a gene encoding a 31 kDa B. abortus antigen. The test was shown to be sensitive, and specificity was demonstrated using DNA derived from a panel of Gram-negative pathogens. There was no detectable difference between B. melitensis and B. abortus in the sensitivity of the reaction or in the size of the amplification product. The technique should be applicable in the diagnosis of brucellosis.
TL;DR: It is hypothesize that the strain‐related increase in PGE influences the synthetic activity of surface bone cells directly, whereas the strain-related increased in PGI2 additionally influences modeling and remodeling through the production of a cytokine or growth factor for which the loading‐related RNA is coded.
Abstract: The continuing ability of the skeleton to withstand functional loads without damage requires that bone mass and architecture are adjusted according to the loads experienced. Load bearing is the only functional influence that requires a particular bone architecture, and functionally engendered strains within the bone tissue provide the only feedback containing the necessary information on the relationship between current architecture and prevailing load history. The specific strain-related objectives of the adaptive modeling and remodeling response to load bearing have not been adequately defined. They appear to be different for cortical and cancellous bone and vary according to cortical location. Experiments suggest that adaptive modeling and remodeling is sensitive to dynamic but not static strain change and that the osteogenic response to a period of dynamic strain is quickly saturated but is higher when the rate of change in strain is high and the distribution of strain unusual. Presumably it is the cumulative effect of this osteogenic response to load bearing that normally maintains bone mass above that seen in disuse situations. Through their independent effects on bone cell behavior, nutritional and hormonal factors can enable, enhance, limit, or frustrate full expression of the osteogenic response to strain change. However, such systemic factors do not appear to be able to engender or successfully imitate the sustained cumulative local response to load bearing that normally maintains functionally appropriate bone mass and architecture. Experiments in vivo and in vitro suggest that in osteocytes and surface osteoblasts the almost immediate response to strain change is increased production of prostacyclin. Surface osteoblasts also produce prostaglandin E.(ABSTRACT TRUNCATED AT 250 WORDS)
Book•
01 Aug 1992TL;DR: A large number of trials in patients with cancer or infections suggest that certain liposomal drug formulations are likely to prove clinically useful, and liposome-entrapped drugs and vaccines exhibit superior pharmacological properties to those observed with conventional formulations.
Abstract: Liposomes (phospholipid-based vesicles) have been investigated since 1970 as a system for the delivery or targeting of drugs to specific sites in the body. Because of their structural versatility in terms of size, composisition, surface charge, bilayer fluidity and ability to incorporate almost any drug regardless of solubility, or to carry on their surface cell-specific ligands, liposomes have the potential to be tailored in a variety of ways to ensure the production of formulations that are optimal for clinical use. This includes controlled retention of entrapped drugs in the presence of biological fluids, controlled vesicle residence in the blood circulation or other compartments in the body, and enhanced vesicle uptake by target cells.
TL;DR: An aggressive approach to cholesterol reduction features in most of the official guidelines for the primary prevention of coronary heart disease, and high percentages of the British population would become candidates for drug treatment if the guidelines currently advanced by some authorities were put into practice.
Abstract: Recent reviews of the primary prevention of coronary heart disease through lowering cholesterol concentrations have varied considerably in their evaluation of the benefits of the intervention. 1-4 The degree of disagreement is surprising as they review essentially the same data, from clinical trials of cholesterol lowering by drugs or by diet. There is agreement about a reduced risk for coronary events, but there are differing interpretations of the increase in mortality from non-cardiovascular causes that has generally been seen. Particular concern was generated by a recent meta-analysis that showed a significantly increased risk of death from accidents and violence when the results of six randomised primary prevention trials were pooled.3 Despite the uncertainty an aggressive approach to cholesterol reduction features in most of the official guidelines for the primary prevention of coronary heart disease.` In Britain the introduction of the new general practitioner contract, with its focus on health promotion, is likely to result in an increase in cholesterol testing. High percentages of the British population would become candidates for drug treatment if the guidelines currently advanced by some authorities were put into practice. For middle aged men and women with other coronary risk factors the European Atherosclerosis Society recommends a cut off level, above which the use of lipid lowering drugs should be considered,6 well below the mean population cholesterol concentration.0`'2 The entry criteria for the expanded clinical evaluation of lovastatin study (EXCEL)\"5 would include a third of the British population. 10-12
TL;DR: The increase in plasma endothelin-1 and endethelin-3 concentrations in patients with the hepatorenal syndrome is consistent with the hypothesis that these substances have a role in the pathogenesis of the disease.
Abstract: Background. Severe renal vasoconstriction is central to the pathogenesis of renal failure in the hepatorenal syndrome. Endothelin-1 and endothelin-3 are potent, long-acting vasoconstrictors, and endothelin-1 has selective potency as a renal vasoconstrictor. These properties suggest a role for endothelins in the hepatorenal syndrome. Methods. We measured plasma endothelin-1 and endothelin-3 concentrations using specific radioimmunoassays in subjects with the hepatorenal syndrome, liver disease but normal renal function, chronic renal failure, acute renal failure, liver dysfunction and renal impairment, or normal liver and kidney function. Results. The patients with the hepatorenal syndrome had markedly elevated mean (±SE) plasma concentrations of endothelin-1 (36±5 ng per liter [14.5±1.8 pmol per liter]) and endothelin-3 (43±3 ng per liter [16.3±1.0 pmol per liter]) as compared with the normal subjects (endothelin-1, 4±1 ng per liter [1.7±0.2 pmol per liter]; and endothelin-3, 18±1 ng per liter [6...
TL;DR: It is suggested that an experimental approach must be combined with a psychometric one to obtain answers which go beyond the sterility often associated with a purely correlational approach, as suggested by Cronbach.
TL;DR: The Worry Domains Questionnaire (WDQ) as mentioned in this paper yields a global score which is calculated by summing scores on five subscales: these subscales, or domains, are labelled (1) Relationships (2) Lack of Confidence (3) Aimless Future (4) Work Incompetence and (5) Financial).
TL;DR: Quantitation of the 5 kb 'common' deletion of mtDNA using PCR revealed a progressive accumulation with age, from approximately 1 in 100,000 at 21 years to 1 in 10,000 in 56 years and 1 in 5000 at 78 years of age.
TL;DR: Sensitivity of the VA technique was greater than 75% for measles, neonatal tetanus, malnutrition, and trauma-related deaths; however, malaria, anaemia, acute respiratory-tract infection, gastroenteritis, and meningitis were detected with sensitivities of less than 50%.
01 Jan 1992
TL;DR: In this article, a scaled sandbox model was used to simulate the growth and sequential development of critical thrust wedges in isotropic cohesionless and anisotropic cohesionless materials.
Abstract: Scaled sandbox models have been used to simulate the growth and sequential development of critical thrust wedges in isotropic cohesionless and anisotropic cohesionless materials. Variations in the initial thickness of the layered sequence, the friction of the basal detachment, and the anisotropy of the layered system have been systematically investigated. Imbricate fans of dominantly foreland-vergent thrust systems are developed similar to those found in accretionary prisms and in foreland fold and thrust belts. Critical taper wedges close to theoretically predicted geometries are developed for intermediate values of basal friction (µb = 0.47 whereas for the lower value of basal friction low-taper wedges are formed with tapers less than predicted by theory. Supra-critical wedges are formed when the basal friction equals or is greater than the coefficient of friction in the wedge and the wedge has a high taper closer to the angle of rest for the modelling material. The spacing/thickness ratio of foreland-vergent thrusts increases as the layer thickness increases. The spacing of thrust faults increases with increased basal friction. Higher basal friction or anisotropy within the layered systems favours displacement along foreland-vergent thrusts and suppresses backthrusts.
TL;DR: In both groups glucose intolerance was more strongly associated with waist-hip girth ratio than with skinfolds or body mass index, and the association between hyperinsulinaemia and obesity is less specific for centrally-distributed fat.
Abstract: Type 2 (non-insulin-dependent) diabetes mellitus and insulin resistance are associated with centrally-distributed obesity. These disturbances are especially prevalent in people of South Asian (Indian, Pakistani and Bangladeshi) descent. We examined the relationship of glucose intolerance to body fat pattern in a population survey of 2936 men and 537 women of South Asian and European origin living in London, UK. In both groups glucose intolerance (defined as diabetes or impaired glucose tolerance) was more strongly associated with waist-hip girth ratio than with skinfolds or body mass index. The associations between body mass index and glucose intolerance were fully accounted for by waist-hip ratio. In European men with normal glucose tolerance fasting insulin levels were more strongly correlated with body mass index than with waist-hip ratio. Physical activity scores were lower in South Asians than in Europeans but no statistically significant associations between glucose intolerance and low physical activity were detectable. Leisure-time physical activity scores were inversely correlated with 2 h insulin levels in both groups. In contrast with other studies these results suggest that a specific effect of intra-abdominal fat deposition underlies the association between glucose intolerance and obesity. The association between hyperinsulinaemia and obesity is less specific for centrally-distributed fat. When measured appropriately waist-hip ratio is the most valid anthropometric index for identifying individuals whose obesity predisposes them to glucose intolerance.
TL;DR: Attentional responses to threat stimuli were assessed in anxious patients, normal controls, and subjects who had recovered from a clinical anxiety state to try to understand the motivation behind these responses.
Abstract: Attentional responses to threat stimuli were assessed in anxious patients, normal controls, and subjects who had recovered from a clinical anxiety state. The main aims of the study were: (1) to rep...
TL;DR: Interestingly, proliferative responses to some regions of the molecule, including some highly conserved sequences, were highest in young children and decreased markedly with increasing age, and high concentrations of antibodies to a conserved region close to the N terminus of Pf MSP1 were also significantly associated with protection.
Abstract: Summary We have investigated the pattern of acquired immune responses to the major surface protein of Plasmodium falciparum merozoites (gp 190, Pf MSP1) in a malaria endemic population in West Africa. A prospective longitudinal study in 3- to 8-year-old children was conducted to examine the relationship between naturally acquired immune responses to Pf MSP1 and subsequent susceptibility to malaria infection and clinical disease. A population cross-sectional survey was performed to investigate changes in immune response with age. The prevalence and concentration of antibodies to all regions of the molecule increased with age with the highest prevalence of antibodies being detected against regions of the molecule which are highly conserved between parasite isolates. In vitro lymphoproliferation and interferon-gamma production in response to recombinant proteins representing polymorphic regions of the molecule also increased with age. Interestingly, proliferative responses to some regions of the molecule, including some highly conserved sequences, were highest in young children and decreased markedly with increasing age. Significant associations were observed between antibody and lymphoproliferative responses to proteins from the C terminus of the molecule and resistance to episodes of fever associated with high parasitaemia in partially immune children. In addition, high concentrations of antibodies to a conserved region close to the N terminus of Pf MSP1 were also significantly associated with protection.
TL;DR: This poster presents a poster presented at the 2016 World Health Organization (WHO) conference on infectious disease in children and young people and focuses on the treatment of diarrhoea and vomiting in children aged five to eight years.
Abstract: Lorenzo Savioli’, Don Bundy’ and Andrew Toni ‘WHO Collaborating Centre on the Epidemiolop of Intestinal Parasites, Department of Biology, Imperial College of Science, Technology and Medicine, London, UK; Centre for International Child Health, Institute of Child Health, University of London, UK
TL;DR: The results illustrate the importance of previously existing symptoms, stereotyped beliefs and social factors in explanations of climacteric symptoms, as well as general health, use of medical services and beliefs about the menopause.