Showing papers by "University of London published in 1983"

Presynaptic Cholinergic Dysfunction in Patients with Dementia

Abstract: Indices of presynaptic cholinergic nerve endings were assayed in neocortical biopsy samples from patients with presenile dementia. For those patients in whom Alzheimer's disease was histologically confirmed, [14C]acetylcholine synthesis, choline acetyltransferase activity and choline uptake were all found to be markedly reduced (at least 40%) below mean control values. The changes occurred in samples from both the frontal and temporal lobes and for [14C]acetylcholine synthesis the decrease was similar under conditions of high and low neuronal activity (as assessed by incubations in 31 mM and 5 mM K+ respectively). Samples from other demented patients, in whom the histological features of Alzheimer's disease were not detected, produced values for all three biochemical parameters which were similar to controls. For the total group of patients with presenile dementia there were correlations between values for the three markers of presynaptic cholinergic nerve endings suggestive of a loss of functional activity at these sites in Alzheimer's disease.

Cognitive deficits in the pathogenesis of autism

Abstract: En rupture avec les conceptions initiales proposees de l'autisme, l'auteur soutient que ce trouble ne consiste pas dans un trouble d'abord affectif, ni ne se limite a un deficit du registre du langage, ni ne se definit par les handicaps sociaux qui affectent le sujet, mais que l'autisme est fonction d'un deficit crucial dans le domaine cognitif. Ce deficit cognitif est fondamental au double sens du terme, dans le mœsure ou il n'est pas secondaire aux autres traits qui caracterisent l'autisme et ou il est sous-jacent aux autres handicaps qui accompagnent l'autisme. Considerant cette definition comme un acquis des recherches les plus recentes, l'auteur pose la question des relations de cette dimension cognitive fondamentale dans l'autisme aux dimensions du desir et de l'affect

Children in lesbian and single-parent households: psychosexual and psychiatric appraisal

Abstract: SUMMARY Thirty-seven school-age children reared in 27 lesbian households were compared with 38 school-age children reared in 27 heterosexual single-parent households, with respect to their psychosexual development and their emotions, behaviour and relationships. Systematic standardized intervews with the mothers and with the children, together with parent and teacher questionnaires, were used to make the psychosexual and psychiatric appraisal. The two groups did not differ in terms of their gender identity, sex role behaviour or sexual orientation. Also, they did not differ on most measures of emotions, behaviour and relationships-although there was some indication of more frequent psychiatric problems in the single-parent group. It was concluded that rearing in a lesbian household per se did not lead to atypical psychosexual development or constitute a psychiatric risk factor.

A cluster approach to the structure of imperfect materials and their relaxation spectroscopy

Abstract: A new theory is proposed for the explanation of observed relaxation phenomena, which differs significantly from theories suggested by the authors before. The theory is based on a model of structural organization of macroscopically sized samples of imperfectly structured materials, both solids and liquids, and is intermediate in character. In terms of the model, a microscopic structure is maintained over a cluster containing a number of microscopic units, with an array of clusters described by a steady-state distribution completing the macroscopic picture. The structural regularity of each level of morphological organization is precisely defined by a coarse-grained index, which is given a thermodynamic interpretation in terms of binding energies and configurational entropy. The limiting cases of an ideal liquid and a perfect crystal are recovered as asymptotic extremes in terms of this definition. The consequences of this model for the relaxation dynamics of the structure are examined and it is shown that prepared fluctuations decay in a time-power law manner as coupled zero-point motions evolve either within clusters or between clusters, with a power determined by the relevant regularity index. As a result, the origin of power law noise in materials is explained in terms of configurational entropy, and its relation with gaussian and white noise, which appear as asymptotic limits, outlined. The shape of the steady-state distribution of the array of clusters is also determined without any a priori assumptions, and it is shown to range from an unbounded form to a δ function as the regularity of the array superstructure increases. Experimental examples of dielectric relaxation spectroscopy have been used to illustrate these structural concepts and outline the way in which this technique can be used to deduce the structural organization of the sample. Finally, a short description is given of some commonly observed forms of response and their structural interpretation.

Measuring the Impact of Water Supply and Sanitation Investments on Diarrhoeal Diseases: Problems of Methodology

Abstract: A review of the published literature on the impact of water supply and/or excreta disposal facilities on diarrhoeal diseases, or on infections related to diarrhoea, reveals several methodological problems that hamper the drawing of definitive conclusions from these studies. This paper examines eight of these methodological problems: lack of adequate control, the one to one comparison, confounding variables, health indicator recall, health indicator definition, failure to analyse by age, failure to record usage, and the seasonality of impact variables. It is suggested that an evaluation of the impact on health of environmental interventions may best be undertaken by the combined efforts of engineers, social scientists and epidemiologists in 'opportunistic' settings and that the intervening behavioural processes so necessary for health impact to occur should be a primary focus of such evaluations.

The Occurrence and Ecology of Recent Rhodoliths — A Review

Abstract: Rhodoliths (= rhodolites, coralline algal nodules) are nodules and unattached branched growths with a nodular form composed principally of coralline algae.

The conodont animal

Abstract: A unique specimen of a small, elongate, soft-bodied animal from the Lower Carboniferous of the Edinburgh district, Scotland, is described. The head expands anteriorly into two lobate structures flanking a central lumen; behind this lies a conodont apparatus, apparently in situ, consisting of an aligned set of ramiform elements followed by a pair of ozarkodiniform elements and one of platform elements. From the morphology of the platform elements the animal has been identified as Clydagnathus? cf. cavusformis. Repeated structures which may represent segments are evident in the posterior part of the trunk, which bears a posterior and a caudal fin, each supported by rays. The animal shows similarities to both chordates and chactognaths, but the evidence supports its assignment to a separate phylum, the Conodonta. The function of the conodonts remains equivocal, but it seems more likely that they served as teeth than as internal supports.

The Immune Response

Abstract: Trichinella spiralis is a highly successful parasite in that it can establish, develop, and reproduce in a wide range of vertebrate hosts. This low host specificity implies that the organism has the ability to adapt to a variety of environmental conditions and hence is relatively unaffected by many of those aspects of natural immunity that impose a more rigid specificity on other species. However, in common with all metazoan parasites, T. spiralis presents the host with a complex antigenic stimulus and thus evokes a powerful immune response. The complexity of the stimulus arises not only from the diversity of antigens present at any one time, but also from the fact that antigens may show stage specificity, changing qualitatively and quantitatively throughout development, and may be released in different tissues of the body. Many components of the immunological response probably have little or no effect on either host or parasite, though they may prove useful in diagnosis; some are deleterious to the parasite and provide protective resistance against infection, yet others are actually or potentially harmful to the host, either from their involvement in immunopathological reactions or through their modulation of unrelated immune responses. This chapter will concentrate on those responses that confer resistance on the host; immune responses in the contexts of diagnosis and pathology are dealt

Cutaneous factors related to the risk of malignant melanoma.

Abstract: In a case-control study, 287 women with malignant melanoma were compared with 574 age-matched controls. Red hair colour at age 5 years was associated with a tripling of risk [relative risk (RR) = 3.0], blonde hair with a 60% increase (RR = 1.6) and fair skin with a doubling (RR = 2.1). Women with melanoma also reported that they tended to burn (RR = 1.4) and to freckle (RR = 1.9) after exposure to sunlight. Since fair skin, red hair, and the tendency to burn or freckle after exposure to sunlight all cluster in the same individuals, the extent to which each of these factors had an independent influence on susceptibility to melanoma was investigated. Hair colour, especially red hair, proved to be the major determinant, followed by skin colour. The reporting of above average numbers of naevi on the body was as strong a predictor of melanoma as was red hair colour (RR = 3.4). A history of psoriasis was also more common in cases than controls (RR = 3.0) as was a history of vitiligo (RR = 1.8). A history of acne appeared to be protective (RR = 0.4) as did a history suggestive of chloasma (RR = 0.6) and premature greying of the hair (RR = 0.6). These relationships were irrespective of hair and skin colour.

Nonlocality and the Kochen-Specker paradox

Abstract: A new proof of the impossibility of reconciling realism and locality in quantum mechanics is given. Unlike proofs based on Bell's inequality, the present work makes minimal and transparent use of probability theory and proceeds by demonstrating a Kochen-Specker type of paradox based on the value assignments to the spin components of two spatially separated spin-1 systems in the singlet state of their total spin. An essential part of the argument is to distinguish carefully two commonly confused types of contextuality; we call them ontological and environmental contextuality. These in turn are associated with two quite distinct senses of nonlocality. We indicate the relevance of our treatment to other related discussions in recent literature on the philosophy of quantum mechanics.

Plant/animal interactions during the upper carboniferous

Abstract: This paper discusses evidence for plant/animal relationships in the Upper Carboniferous. Close interactions are examined from the study of fossil plants and animals preserved in coal swamp and coastal plain environments. Evidence for plant/animal interactions is in the form of: (1) animal morphology, including both vertebrates and invertebrates. The vertebrates are dominated by amphibians; however, a few reptiles are known and are mostly carnivores or insectivores. The invertebrate communities are dominated by arthropods, many of which are herbivores. Millipedes, springtails and mites are present on the forest floor and in peats, with insects dominating above ground environments. The diets of the animals have been studied using evidence from gut contents, coprolites, anatomy and comparisons to modern representatives. (2) Plant morphology, including positive stimulation (i.e., dispersal vectors) or in terms of negative stimulation such as protection against herbivory. These data include plant anatomy and morphology, evidence of herbivory in the form of chewed leaves, bored seeds and megaspores, etc. Evidence is provided that suggests that the medullosan seed fern pollen typeMonoletes may have been dispersed by animal vectors. Information on plant/animal relationships in a single environment is based on a study of coprolites extracted from permineralizations (coal balls). Assemblages of coprolites found in these coal balls suggest that they were formed principally from mites, Collembola and millipedes, and demonstrates that the association of soil arthropods, which is important in modern soil ecosystems, was already dominating similar environments in the late Carboniferous. The abundant fossil evidence for plant/animal interrelationships during the Upper Carboniferous should be evaluated when considering co-evolution.

Diabetes mortality: new light on an underestimated public health problem.

Abstract: Mortality from diabetes is underestimated four- to fivefold by methods of analysis of death certification data which use only underlying cause of death. This problem is partially overcome by coding all conditions mentioned on death certificates. For a sample of deaths in England and Wales over the years 1972–1977, the observed proportion of certificates with specific underlying causes of death for certificates mentioning diabetes was compared with the expected proportion for all certificates. These observed/expected ratios were significantly increased in each sex for circulatory diseases and were significantly reduced for neoplasms. For ‘nephritis’ they were also increased, especially below 45 years of age. These results were confirmed by an analysis of underlying cause of death in a cohort of nearly 6,000 members of the British Diabetic Association. Of the 2,134 deaths in this cohort, diabetes was not mentioned on 33% of the death certificates. For the period 1972–1977, death rates for circulatory diseases associated with diabetes increased by 6% for males but remained constant for females.

Description and Classification of Rhodoliths (Rhodoids, Rhodolites)

Abstract: Nodules composed of coralline algae have been described since the latter part of the eighteenth centuary (Pallas 1766, Ellis and Solander 1786). The first extensive descriptive work on free-living corallines was undertaken by Foslie (1894), Lemoine (1910) and later by Cabioch (1966, 1969). Bosellini and Ginsburg (1970) were the first to recognise the palaeoecological significance of rhodoliths and they suggested a descriptive terminology. They proposed the term rhodolite for “... nodules and detached branch growths with a nodular form composed principally of coralline algae ...”. Unfortunately the term rhodolite has priority for a variety of garnet (Binda 1973) and therefore “rhodolith” has now become the accepted term (Toomey 1975). More recently “rhodoid” has been suggested (Peryt, this vol.) but this is not preferred by the author because (a) an acceptable term is already in use and (b) its etymology is unsuitable (Rhodolith-rhodophycean or red stone, rhodoid-rhodophycean or red-like).

Genetic evidence that a Y-linked gene in man is homologous to a gene on the X chromosome.

Abstract: The mammalian sex chromosomes are thought to be related to each other by sharing a common origin. That is, the X and Y chromosomes originally evolved from a pair of chromosomes that only differed at the locus determining sexual differentiation1,2. For example, this evolutionary relationship is reflected during meiosis3 in chromosomal pairing between the tip of the human X chromosome short arm and the Y chromosome which presumably implies sequence homology4. However, compelling genetic evidence for functional homology between the mammalian X and Y chromosome is lacking. We describe here the localization of a gene to the tip of the short arm of the human X chromosome and evidence for a related gene on the Y chromosome.

Biochemical Evidence of Selective Nerve Cell Changes in the Normal Ageing Human and Rat Brain

Abstract: Atrophy with ageing of human whole brain, entire temporal lobe, and caudate nucleus was assessed in autopsy specimens, by biochemical techniques. Only the caudate nucleus showed changes. Markers for several neurotransmitter systems were also examined for changes with age. In neocortex and temporal lobe of human brain, small decreases were detected in markers of cholinergic nerve terminals, whereas a large decrease (79%) occurred in the caudate nucleus. Findings were similar in striatum from 3--33-month-old rats. No change occurred in binding of [3H]quinuclidinyl benzilate by human samples. Markers of serotonergic terminals were also unchanged in human and rat brain. By contrast, binding of [3H]lysergic acid diethylamide and [3H]serotonin was decreased (32-81%) in human neocortex and temporal lobe, but not in caudate nucleus. A 43% loss of a marker of gamma-aminobutyrate terminals occurred in human neocortex, while [3H]muscimol binding increased (179%). No changes were detected in markers of catecholamine synapses in temporal lobe or rat striatum. Hence, with human ageing there appears to be a loss of markers of gamma-aminobutyrate neurones intrinsic to neocortex and acetylcholine cells intrinsic to the caudate nucleus, as well as a change in postsynaptic serotonin receptors in neocortex. These losses are accompanied by relative preservation of markers of ascending projections from basal forebrain and brain stem.

Transmission of Plant Viruses

Abstract: Plant viruses are obligate parasites, often causing the death of their host, so it is necessary for them to spread from plant to plant and to be introduced into living cells. This spread or transmission will be considered under the following headings: (1) mechanical transmission (2) vegetative, graft and dodder transmission (3) transmission by pollen seeds (4) insect and mite transmission (5) nematode and fungal transmission.

Medical care in developing countries. Assessment and assurance of quality.

Abstract: In recent years attention in developing countries has concentrated upon strategies to improve the equitable provision of essential health care-the primary health care approach. Very little work has been reported in connection with the quality of medical care, and yetfor the successful outcome of care it is necessary that adequate health care processes be carried out. Conceptual, methodological, data, and organizational issues related to quality assessment and assurance are presented. Thefew examples of reported work concerned with these important aspects of medical care in developing countries are reviewed. Suggestions are made as to how measures to ensure reasonable quality might be further developed and refined.

Effects of cadmium and lead on radish plants with particular reference to movement of metals through soil profile and plant

Abstract: Studies were made of the effects of insoluble and soluble compounds of Cd and Pb on the growth of radish plants. The effect of Cd toxicity was progressive chlorosis, particularly of the young leaves, followed by necrosis. The effect of Pb toxicity was stunted growth. Root growth was more inhibited than shoot growth in metal-contaminated soils. On a molarity basis Cd was twenty times more toxic than Pb.

Metabolic processes in Alzheimer's disease: adenine nucleotide content and production of 14CO2 from [U-14C]glucose in vitro in human neocortex.

Abstract: Samples of neocortex removed at diagnostic craniotomy from patients with Alzheimer's disease and incubated in vitro showed an increased production of 14CO2 from [U-14C]glucose compared with neurosurgical controls. This was a feature of incubations in the presence of both 5 mM K+ (142% control) and 31 mM K+ (126%). Specific labelling of the amino acid pool was unaltered, suggesting that the apparent increase of CO2 production was not merely a reflection of changes in dilution of the radiolabel from glucose. The content of adenine nucleotides was significantly less than control values in the tissue from patients with Alzheimer's disease after in vitro incubations but the adenylate energy charge was unchanged, indicating that normal energy metabolism was not grossly impaired in these preparations.