SEARCH · PubMed Health

Results for “Disjunction”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 991 records · Page 55Linked to original sources

PubMed1986

Developmental changes of oculomotor characteristics in infants when awake and in the 'active state of sleep'.

Since the principal criterion for identifying sleep in the young infant is eye closure, a study was undertaken to ascertain whether fast or 'saccadic-type' movements which occur in the eyes-closed condition differ in any respect from those which are observed in the eyes-open (awake) state. Specific parameters included the amplitude-velocity relationship, the numbers and types of non-conjugate movements (disjunctive and monocular), directionality and densities (EM/min). Measurements were made on 12 infants at 4-week intervals as they progressed in age from 4 weeks to 12 weeks. The results disclosed that in the main as the infants developed, a change, if any, of ocular characteristic in the awake state was paralleled by a similar change in the eyes-closed state, although the absolute number of eye movements was higher in the eyes-open state compared to the eyes-closed state. This suggests that the eye movement characteristics, whether the eyes were open or shut, were dictated primarily by oculomotor development and the mechanics of eye closure rather than by different mechanisms of neural control effected through different states of consciousness. Of special interest was the finding that the velocity-amplitude relationship in the infant's eyes-open state was almost identical to that reported for adults in the eyes-open state whereas the value for the eyes-closed state was comparable to that of the adult's eyes-closed awake state rather than to the value obtained for adults in REM sleep.

Aging↗

PubMedDate not supplied

Brain organization and sleep function.

A view of brain organization and sleep function is presented. Sleep is hypothesized to begin at the neuronal group level. Sleep results in the use and thus maintenance, of synapses that are insufficiently stimulated during wakefulness thereby serving to preserve a constancy of a synaptic superstructure. It is further hypothesized that sleep at the neuronal group level is regulated by the production of substances whose rate of production or catabolism is synaptic use-dependent. If sufficient number of neuronal groups are in a sleep state (also called disjunctive state) then the perception of sleepiness occurs. Coordination of neuronal group sleep results from humoral and neuronal projection systems previously linked to sleep regulation. The theory presented is unique in that it: (a) hypothesizes an organizational level at which sleep occurs; (b) hypothesizes that sleep is neuronal--use-dependent, not wakefulness-dependent; (c) hypothesizes that sleep first occurs in evolution when complex ganglia evolved; and (d) hypothesizes the both non-rapid eye movement sleep (NREMS) and REMS serve the same function of synaptic reorganization. The theory is consistent with past theories of sleep function, yet provides a fundamentally new paradigm for sleep research.

Animals↗

PubMed1990

Evolution of nuclear DNA and the occurrence of sequences related to new small chromosomal DNAs in the trypanosomatid genus Endotrypanum.

Comparisons of nuclear DNA restriction fragment patterns were used to examine the evolutionary relatedness among 17 strains previously identified as Endotrypanum, a trypanosomatid parasite of sloths. Fragments were obtained with 6 restriction enzymes and analyzed by Southern blotting with hybridization probes from three loci. An estimate of the percent nucleotide sequence divergence among strains, delta, was calculated and used to construct molecular evolutionary trees. The 17 isolates fell into four distinct groups, one of which (group D) showed no more relationship to groups A-C than it did to other genera (Leishmania, Crithidia, Leptomonas, Trypanosoma), being too distant to be resolved with this method. These and other data suggest that group D may not actually be Endotrypanum. Molecular karyotype analysis revealed considerable variation among the chromosomes of these strains. One strain (LV88, group B) contained a linear 70-kb chromosome not evident in other isolates. Hybridization probes specific for this chromosome (LV88-70) were developed and revealed that related sequences were present at high levels in group B isolates and low levels in group A isolates, although a complex hybridization pattern was evident. Sequences related to LV88-70 were not present in groups C and D, nor in Leishmania major, showing that this DNA has a disjunct distribution which curiously parallels that of virus-like particles present in these isolates.

Animals↗

PubMed1984

Linear and nonlinear models of patient satisfaction with medical care.

The relationship between overall patient satisfaction with medical care and satisfaction with various aspects of health services is explored in a community survey of 225 service consumers. Three alternative models are examined: (i) linear compensatory model; (2) nonlinear conjunctive model; and (3) nonlinear disjunctive model. The results indicate that the nonlinear, noncompensatory models predict overall satisfaction as well as does the linear compensatory model. The pattern of findings is different for men and women. The implications of the findings are discussed.

Adult↗

PubMed1986

Doors and thresholds: Jeddi's approach to psychiatric disorders.

Professor Essedik Jeddi and his team have introduced a most significant institutional and therapeutic innovation at the Ibn Rochd and Pinel section of the Razi university long-term mental hospital in Tunis (Tunisia). The innovation focuses upon the ambiguity of doors and boundaries in the mental asylum. Doors and walls influence the rhythm of activity and the nature of contact between patients, therapists and the wider society and culture. If they are very rigid, they may disjoin the patient from him- or herself, from his/her body, social network and culture. On the other hand, if such boundaries are completely neglected they may merge these related dimensions as undifferentiated entities. Jeddi's innovation is primarily concerned with placing the spatio-temporal experience of the body and the intimate interpersonal interaction at the centre of treatment. It aims at establishing creative modes of expression, interaction and exchange such as tea-sessions, dancing, singing, verbal communication, clay-modelling, figurative or plastic expression, agricultural works. These relationships mediate and differentiate at the same time between the patient, his/her body-self, and his/her social and cultural world, thus avoiding both the disjunction and the merging. It would seem that the activities concerned with the distinction between 'inside' and 'outside', peasant and urban, self and other (e.g. dancing and singing) are of paramount importance in bringing about such mediating and differentiating relationships. In the present study we limit ourselves to one particularly revealing therapeutic activity, namely dancing to live music. Jeddi's innovation is a unique blend of current developments in psychiatry and psychotherapy with Arabo-Islamic science and philosophy.

Cultural Characteristics↗

PubMed1994

Exorcists, psychiatrists, and the problems of possession in northwest Madagascar.

For the Sakalava of northwest Madagascar, spirit possession and madness occupy opposing poles on a spectrum of experiences which, in indigenous terms, range from a good, powerful, and inescapable state to a destructive, dangerous, and frightening illness. While possession by the most powerful spirits is honorable and permanent, the excessive suffering that some mediums experience leads them to seek a way out; in other cases, chronic madness frustrates the afflicted and their kin who search for, but rarely find, a cure. Psychiatrists and protestant exorcists offer last resort options to these individuals, but the efficacy of their treatments varies greatly. While patients and healers are all Malagasy, sub-ethnic divisions are, nevertheless, crucial to defining the tensions that arise within these two alternative therapeutic contexts. The relevance of each approach and efficacy of its associated treatments hinge on the success of the psychiatrist and exorcist to mediate between these ethnic divisions. In turn, each practitioner is faced with the task of integrating conflicting epistemological realities surrounding illness. While exorcisms may be painful and frustrating to patients, the exorcists are more successful as healers, since they first accept and then transform the patients' explanations for and experiences of possession and madness. During protestant healing rituals, possession is viewed as an appropriate idiom for describing illness, and madness is redefined as normative, not deviant, behavior. Failure among psychiatrists can be traced to their inability to comprehend or accept their patients' experiences, a disjunction exacerbated by their acceptance of a cognitive model based on western sensibilities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1986

Investigation of coffee in Drosophila genotoxicity tests.

Two preparations of coffee (instant coffee and freeze-dried home-brew coffee) were tested in different mutagenicity assays in germ cells as well as in somatic cells of Drosophila melanogaster. The three end-points assayed in germ cells were sex-linked recessive lethals (mainly gene mutations and small chromosome aberrations), dominant lethals (cytotoxic effects as well as genotoxic effects) and sex-chromosome losses (chromosome breakage and non-disjunction). The aqueous coffee solutions were fed either to adult male flies for 3 days or to growing larvae during the whole larval development. Treated males were crossed with appropriately marked females, and the different genetic end-points were analysed in the F1 or F2 generation. The test concentrations (instant coffee 4% (w/v), home-brew coffee 3%) were acutely toxic in adult males (killing approximately 75 and 90% of the exposed flies, respectively). No increase in deaths was caused in larvae by the same concentrations. Only cytotoxic effects were observed in the test for dominant lethals. No conclusive genotoxic effects could be detected in any of the three germ cell assays. The coffee preparations were also tested for induction of mutation and mitotic recombination in somatic cells of the wing imaginal disc. Larvae trans-heterozygous for two recessive wing hair markers were fed high concentrations of the coffees for varying periods of time. Wings of surviving adult flies were analysed for mosaic spots. Twin spots exhibiting both mutant phenotypes are produced by mitotic recombination; single spots showing one or the other phenotype are the result of somatic mutation, such as gene mutation or deletion, or of mitotic recombination. Both coffees had weak effects on normal (repair-proficient) cells as well as on excision repair-defective cells in this assay. Additional experiments with pure caffeine and decaffeinated coffee show that these weak effects in somatic cells were most probably caused by the caffeine present in the two coffees.

Animals↗

PubMed1976

Relationship between SCR, heart rate and information processing.

This study was designed to investigate the relationship between the amount of information processing in concept learning (CL) and autonomic physiological activity as measured by skin conductance response (SCR). Heart rate (HR) was also measured. Two conceptual rules were used: a conjunctive and an inclusive disjunctive concept. The results indicated that the SCR rose with increasing amount of information processing at the feedback during CL. Furthermore, it was shown that SCR increased with increasing difficulty of the conceptual rule. HR appeared not to vary with amount of information processing, nor with type of concept. In the conjunctive series, however, there was a significant difference between HR at stimulus presentation and HR at feedback.

Concept Formation↗

PubMed1986

The optic tectum of gymnotiform teleosts Eigenmannia virescens and Apteronotus leptorhynchus: a Golgi study.

Golgi, Nissl, Bielschowsky and cholinesterase techniques have been used to analyze the optic tectum of the weakly electric teleost fish Eigenmannia virescens and Apteronotus leptorhynchus. Six layers are readily distinguished: a fairly thick stratum marginale, a narrow stratum opticum and stratum fibrosum et griseum superficiale, a well-developed stratum griseum centrale, a stratum album centrale and a compact stratum periventriculare. Fifty-six neuronal types are present. In regard to comparative aspects of tectal organization, it became apparent that although most neuronal types are similar to those reported in other teleostean fish, there are certain obvious differences such as: pyramidal cell somata not confined to stratum fibrosum et griseum superficiale, but also clustered in the adjacent stratum opticum, presenting stratified or diffuse basilar dendritic arbors; and a change from vertical to oblique and almost horizontal neuronal orientation in the ventral and caudal tectum. The presence of pyramidal cells with aligned and misaligned apical and basal dendritic fields. A cell of stratum griseum centrale with an ascending axon to stratum opticum. A special projection type of fusiform cell of stratum griseum centrale, with an efferent axon of somatic origin. A cell rich stratum griseum centrale, with a wider variety of multipolar and bipolar cell population than reported in other teleosts. Fourteen types of pyriform cells are present, four of which are efferent. Our observations are suggestive of regional differences in regard to the caudalmost tectum in Apteronotus: presumably this is related to the extremely sparse retinal input to this part of the tectum. A close functional correlation has been found between some multipolar and pyriform cells identified in our material with similar cells reported by Rose and Heiligenberg as multisensory cells, following recordings and horseradish peroxidase fillings of these cells. Based on the observation of patchy torus semicircularis input to stratum fibrosum et griseum superficiale, disjunct from the retinal input to this layer, it is proposed that perhaps this arrangement is the result of competition for synaptic targets during development.

Animals↗

PubMed1980

Defining health.

Societies are here postulated as autopoietic systems, that is, they are living unities the components of which maintain processes that ensure the production of such components. Autopoietic systems are circularly involved in maintaining themselves and society partakes of this selfmaintaining characteristic. Health is a societal concept applied to its component individual human beings and describes their fitness for the survival of the society. Medicine that treats disease is concerned with the individual and his survival. Health caring institutions and concepts (right to health care, health insurance, public health programs) are all societal endeavours that are not designed for individual benefit, but constitute an increasingly important survival strategy of societal unities. It can be anticipated that the most important medical issues in the future (allocation of resources, genetic manipulation, population growth control, right to medical care) will concern the disjunctive efforts of medicine and public health as the respective survival strategies of individuals and societies.

Biological Evolution↗

PubMed1989

Analysis of Aprt deficient mutants of Friend erythroleukaemia cells.

Cytogenetic analysis of mutants of the Friend Erythroleukaemia cell line deficient in adenine phosphoribosyl transferase (Aprt) was undertaken to ascertain whether non-disjunctional events were involved in the production of this mutation. All mutant clones examined were found to carry two copies of chromosome 8, the chromosome to which Aprt maps. Since the two homologues are distinguishable by silver staining, it was also clear that no mutants contained two copies of one homologue having lost the other. Treatment of mutants with 5-azacytidine failed to reactivate the Aprt locus.

Adenine Phosphoribosyltransferase↗

PubMed1996

Saccular impact on ocular torsion.

When someone is tilted laterally, the shear force on the maculae of the utriculus and the sacculus is described by the sine and the cosine of the angle of tilt, respectively. So both the sacculus and the utriculus are stimulated, but in the literature, ocular torsion is normally attributed to utricular function alone (and, thus, seen as a response to y-axis linear acceleration). However, on the base of a series of experiments on a tilt chair, a linear track, human centrifuges, and during parabolic flights, we conclude that the sacculus contributes to ocular torsion as well (there is a response to z-axis linear acceleration). The data suggest that the ratio of the utricular and saccular impact on ocular torsion is 3:1. The utriculus generates conjugate and the sacculus disjunctive torsional eye movements.

Adult↗

PubMed1994

Imaginary constructions and forensic reconstructions of fatal violence against women: implications for community violence prevention.

The almost exclusive media focus on political violence in South Africa has deflected attention from the high levels of interpersonal violence in areas of socioeconomic deprivation. In order to explore the tension between an at-risk community's perspective and the current reality of violence against women, imaginary constructions of their own violent death produced by 45 African female interview respondents were examined in conjunction with forensic data relating to 73 African female homicide victims in Cape Town, South Africa. The prototypical account of an imagined homicide involved a female commuter being approached by a group of men, taunted and assaulted, raped and then killed. The majority of actual homicides occurred at or in the vicinity of the residence of the victim, with the attacker being known to the deceased. Whilst only 1 of the imagined homicide narratives depicted the use of alcohol by the victim, over half the actual homicides had elevated postmortem blood alcohol levels. These and other disjunctions and convergencies between lay and forensic constructions of violent female death should be viewed in the wider context of enmeshment in social circumstance, and could provide some understanding of how at-risk communities perceive violence against women, thereby providing a foundation for appropriate prevention programmes.

Adult↗

PubMed1991

Frequency of trisomy 21 in Germany before and after the Chernobyl accident.

For Berlin (West) the rate of trisomy 21 among newborn and all prenatally diagnosed cases can be almost completely recorded, including the maternal age distribution. During the 9-year-period from 1980 and 1988 the average number of trisomy 21 per month was about 2, following a Poisson distribution. A significant increase (P less than 0.01) was observed in January 1987, exactly 9 months after the Chernobyl accident. In a supraregional study based on greater than 30,000 prenatal diagnoses performed in 1986, no significant effect could be observed. However, the highest rates of trisomy 21 were observed in the more heavily contaminated, southern part of Germany. The majority of these fetuses were conceived during the period of greatest radioactive exposure. The data are discussed with respect to the effect of low-dose radiation around the time of conception on the induction of non-disjunction in man.

Abnormalities, Radiation-Induced↗

PubMed1995

Aneuploidies and micronuclei in the germ cells of male mice of advanced age.

The objective of this research was to determine whether the frequencies of chromosomally defective germ cells increased with age in male laboratory mice. Two types of chromosomal abnormalities were characterized: (1) testicular spermatid aneuploidy (TSA) as measured by a new method of multi-color fluorescence in situ hybridization (FISH) with DNA probes specific for mouse chromosomes X, Y and 8, and (2) spermatid micronucleus (SMN) analyses using anti-kinetochore antibodies. B6C3F1 mice (aged 22.5 to 30.5 months, heavier than controls but otherwise in good health) showed significant approximately 2.0 fold increases in the aneuploidy phenotypes X-X-8, Y-Y-8, 8-8-X and 8-8-Y with the greatest effects appearing in animals aged greater than 28 months. No age effect was observed, however, in X-Y-8 hyperhaploidy. Major age-related increases were seen in Y-Y-8 and X-X-8 hyperhaploidies suggesting that advanced paternal age is associated primarily with meiosis II rather than meiosis I disjunction errors. A approximately 5 fold increase was also found in the frequency of micronucleated spermatids in aged mice when compared with young controls. All micronuclei detected in the aged animals lacked kinetochore labeling, suggesting that they either did not contain intact chromosomes or the chromosomes lacked detectable kinetochores. The findings of the TSA and SMN assays are consistent with meiotic or premeiotic effects of advanced age on germ cell chromosomes, but there were differences in the age dependencies of aneuploidy and micronuclei. In summary, advanced paternal age may be a risk factor for chromosomal abnormalities (both aneuploidy and structural abnormalities) in male germ cells.

Aging↗

PubMed1994

Learning and discovery from a clinical database: an incremental concept formation approach.

The main interest of this research is to discover clinical implications from a large PTCA (Percutaneous Transluminal Coronary Angioplasty) database. A case-based concept formation model D-UNIMEM, a modified version of Lebowitz's UNIMEM, is proposed for this purpose. In this model, we integrated two kinds of class memberships: the feature-disjunction class membership and the index-conjunction class membership. The former is a polythetic clustering approach and serves at the early stage of concept formation. The latter allows only relevant instances to be placed in the same cluster and serves as the later stage of concept formation. D-UNIMEM could extract interesting correlations among features from the learned concept hierarchy.

Abstracting and Indexing↗

PubMed1994

Centrosome and kinetochore movement during mitosis.

During the past year important progress has been made in refining our understanding of how chromosomes become equally distributed to daughter cells during mitosis. Unlike the situation in diatoms and yeast, it now appears that spindle pole (centrosome) separation during spindle formation and anaphase B is mediated in vertebrates primarily by an astral pulling, and not a pushing, mechanism. Kinetochore motility is directionally unstable, which has important consequences for how chromosomes move to the equator of the forming spindle. Finally, the observation that sister chromatid disjunction occurs even in the presence of high levels of maturation promoting factor reveals that the series of biochemical events responsible for this phenomenon is not an obligatory part of the pathway by which the cell exits mitosis.

Anaphase↗

PubMed1993

Trisomy in humans: incidence, origin and etiology.

Molecular studies conducted over the past year have demonstrated the importance of aberrant genetic recombination in the etiology of several human trisomies, and have begun to shed light on the basis of the association between advancing maternal age and trisomy. Preliminary studies of gametes using fluorescence in situ hybridization indicate that this will be a useful approach in the analysis of human non-disjunction.

Animals↗