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PubMed2005

Ascertaining the prevalence of childhood disability.

OBJECTIVES: To reapply 1985 Office of Population Census and Surveys (OPCS) disability survey methods, modified as necessary, to a sample of children to ascertain presence of disability. To compare OPCS-based prevalence with prevalence based on carer's views and medical records. DESIGN: Analytical study. Setting Community Child Health Department in UK. PARTICIPANTS: Principal carers of 100 children aged 5-15, selected from a district special needs register. Main outcome measures Comparable information about disability from three sources and diagnosis from carers and medical records. RESULTS: Medical records of 46% contained a diagnosis. Carers were always aware of this, although a single question did not always elicit their knowledge. OPCS-derived threshold disability criteria in categories of Hand function, Personal care, Consciousness and Continence gave prevalence results similar to medical records and carers. OPCS criteria yielded higher prevalence of disability in the areas of Locomotion (8%), Communication (14%) and Hearing (18%). Carers, OPCS and medical records disagreed markedly about prevalence of disabilities of Vision, probably because of the use of differing definitions. OPCS learning criteria were judged unsuitable and standard attainment targets (SATs) were substituted. These provided similar prevalence figures to carers and medical records. OPCS behaviour criteria were also unsuitable and were replaced by the General Health and Behaviour Questionnaire (GHBQ). This found an increased prevalence of problems compared with carers and doctors. CONCLUSIONS: Diagnostic labels have limited use when collecting data about disabled children. Doubt is cast on the validity of some of the 1985 OPCS threshold criteria, and reassessment is suggested before their future use. Further work is needed on the use of SATs and GHBQ in the benchmarking of disability. To collect population data it would be easier and at least equally effective (with caution in the case of Vision) to ask carers directly rather than applying descriptive thresholds and external judgements. Similar information could be obtained from medical records, however, they are likely to be out of date.

Adolescent↗
PubMed2002

Multiple modes of regulation of Na+/H+ exchangers.

Mammalian Na(+)/H(+) exchangers (NHE) mediate electroneutral countertransport of H(+) for Na(+) across the plasmalemmal and organellar membranes. They contribute to cellular and organellar pH and volume regulation and transepithelial Na(+) transport. The aim of this review is to illustrate the complex regulation of these transporters by focusing on the multiple mechanisms controlling the epithelial isoform, NHE3. A variety of agents and conditions (e.g., hormones, growth factors, cellular pH, and medium osmolarity) act in concert to achieve short-term and long-term regulation of this isoform. The underlying mechanism involves changes in the number of transporters on the cell surface and/or altered activity of the individual exchangers due to allosteric activation by intracellular protons, phosphorylation and interaction with accessory proteins and the cytoskeleton. A similar regulatory versatility probably applies to other NHE isoforms, and the lessons learned from studying members of the NHE family could serve as a useful reference when exploring the modes and levels of regulation of other transporters.

Animals↗
PubMed1999

Parallel activation of primary and secondary somatosensory cortices in human pain processing.

Cerebral processing of pain has been shown to involve primary (SI) and secondary (SII) somatosensory cortices. However, the temporal activation pattern of these cortices in nociceptive processing has not been demonstrated so far. We therefore used whole-head magnetoencephalography to record cortical responses to cutaneous laser stimuli in six healthy human subjects. By using selective nociceptive stimuli our results confirm involvement of contralateral SI and bilateral SII in human pain processing. Beyond they show for the first time simultaneous activation onset of contralateral SI and SII after approximately 130 ms, indicating parallel thalamocortical distribution of nociceptive information. This contrasts to the serial cortical organization of tactile processing in higher primates and instead corresponds to the parallel cortical organization in lower primates and nonprimates. Thus our finding suggests preservation of the basic mammalian parallel organizational scheme in human pain processing, whereas in the tactile modality parallel organization appears to be abandoned in favor of a serial processing scheme. Functionally, preservation of direct access to SII underscores the relevance of this area in human pain processing, probably reflecting an important role of SII in nociceptive learning and memory.

Adult↗
PubMed2001

A variational method for learning sparse and overcomplete representations.

An expectation-maximization algorithm for learning sparse and overcomplete data representations is presented. The proposed algorithm exploits a variational approximation to a range of heavy-tailed distributions whose limit is the Laplacian. A rigorous lower bound on the sparse prior distribution is derived, which enables the analytic marginalization of a lower bound on the data likelihood. This lower bound enables the development of an expectation-maximization algorithm for learning the overcomplete basis vectors and inferring the most probable basis coefficients.

Journal Article↗
PubMed1998

Mental disorder and violence. A special (high security) hospital study.

BACKGROUND: From a first clinical description of a complete resident sample of special (high security) hospital patients, we examined the association between mental disorder and violence. METHOD: A record survey of all 1740 patients resident at any time between 1 January and 30 June 1993, inclusive, and, for most, the official criminal record. RESULTS: 1015 patients (58%) had functional psychosis, one-quarter of whom also had an independent personality disorder; 461 (26%) had personality disorders uncomplicated by psychosis, and 264 (16%) had learning disabilities. Pre-admission substance misuse, which was probably under-recorded, had been most common among those with psychosis and an independent personality disorder. Less than 10% had never been convicted of a criminal offence, although 25% had been admitted directly from other hospitals. Direct personal violence was more common among men, and fire-setting among women. Schizophrenia was most strongly associated with personal violence. More than 75% of those with a psychosis were recorded as being driven to offend by their delusions. In the absence of delusions, hallucinations had no such effect. CONCLUSIONS: For people with personality disorder better clinical descriptions seem essential. For people with a pure psychosis, as symptoms were usually a factor driving the index offence, treatment appears as important for public safety as for personal health.

Adult↗
PubMed1986

An investigation of decision theory: what are the effects of teaching cue recognition?

As currently formulated, decision theory assumes that care givers learn cue recognition primarily by experience. However, it seems probable that the ability to receive and recognize cues can be taught. To investigate cue recognition abilities of junior and senior baccalaureate nursing students, five computer simulations were developed. The specific question investigated was: What are the effects upon students' cue recognition and clinical decision-making abilities of teaching cue recognition? Following teaching of cue recognition and decision making, a statistically significant difference was noted in both junior and senior students in relation to accuracy of cue recognition and clinical decision making. The conclusions were that cue recognition and cue sorting can be taught. Also, linking or grouping of related cues can be taught. In this study, the teaching of cue recognition and linking of cues improved the accuracy of clinical decisions made by students who were presented computer simulations of a variety of clinical situations.

Computer Simulation↗
PubMed1994

[The remarkable debate during the beginning of the nineteenth century concerning the aetiology of scabies].

The scabies mite (acarus or sarcoptes scabiei) was known already to Aristoteles, to the Arabic medicine during the early and to European physicians as well as laymen during the later Middle Ages, depicted in 1687 by Bonomo in Italy and by Schwiebe in Germany during the beginning of the eighteenth century. Later in the middle of the century three pupils to Linnaeus in their doctor's theses stated that the scabies mite (Acarus humanus subcutaneus) was the cause of scabies. The best pictures of the scabies-mite as well as of the flour- and cheese-mite was given by the Swedish entomologist Charles de Geer in 1778. In spite of all these facts the real aetiology of scabies seemed to be unknown in France and in most parts of Europe. This was probably due to the fact that no one had learned the rather simple method to extract the mite from the skin with a needle and thereby verify its existence. In the beginning of the twentieth century scabies was a real problem for the health authorities. In Paris l'Académie de Médecine even offered a reward to the person who could solve the enigma of the itch. Jean Chrysanthe Galés was the pharmacist at l'Hôpital St. Louis, the famous skin hospital in Paris, where at this time about 65 percent of the beds were occupied by patients suffering from scabies. Galés also studied medicine and wanted to write a doctor's thesis. As the theme of a dissertation he was given the cause of the itch. In 1812 he published his thesis ("Essai sur la Gale") including a plate with sketches of mites that he claimed to have extracted from vesicules on the skin of his scabies patients. His findings could not be verified by other investigators. Galés however refused to take part in any control experiments and left the hospital. The debate concerning the supposed cause of the itch continued for two decades both inside and outside the hospital. F.C. Raspail, a famous natural scientist, was interested. After having studied the literature and especially the drawings by de Geer he was convinced that the mites depicted by Galés were similar to de Geers' flour-and cheese mite and that they had no resemblence to his picture of scabies-mite. In a control experiment Raspail could show how Galés had cheated by contaminating his slide with cheese-mites. However, a Corsican student at l'Hôpital St. Louis named S.F. Renucci knew the answer to the riddle. He had long ago been taught by peasant women of his home island how to extract the mite and he could now show the method to the doctors at l'Hôpital St. Louis. this was on August 13 in 1834, which usually in the literature is looked upon as the day when the discovery of the aethiology of scabies was made. Maybe we have a different view in Sweden.

Animals↗
PubMed2001

Towards an inclusive philosophy for phylogenetic inference.

We defend and expand on our earlier proposal for an inclusive philosophical framework for phylogenetics, based on an interpretation of Popperian corroboration that is decoupled from the popular falsificationist interpretation of Popperian philosophy. Any phylogenetic inference method can provide Popperian "evidence" or "test statements" based on the method's goodness-of-fit values for different tree hypotheses. Corroboration, or the severity of that test, requires that the evidence is improbable without the hypothesis, given only background knowledge that includes elements of chance. This framework contrasts with attempted Popperian justifications for cladistic parsimony--in which evidence is the data, background knowledge is restricted to descent with modification, and "corroboration," as a by-product of nonfalsification, is to be measured by cladistic parsimony. Recognition that cladistic "corroboration" reflects only goodness-of-fit, not corroboration/severity, makes it clear that standard cladistic prohibitions, such as restrictions on the evolutionary models to be included in "background knowledge," have no philosophical status. The capacity to assess Popperian corroboration neither justifies nor excludes any phylogenetic method, but it does provide a framework in phylogenetics for learning from errors--cases where apparent good evidence is probable even without the hypothesis. We explore these issues in the context of corroboration assessments applied to likelihood methods and to a new form of parsimony. These different forms of evidence and corroboration assessment point also to a new way to combine evidence--not at the level of overall fit, but at the level of overall corroboration/severity. We conclude that progress in an inclusive phylogenetics will be well served by the rejection of cladistic philosophy.

Likelihood Functions↗
PubMed1990

Classification methods for computerized interpretation of the electrocardiogram.

Two methods for diagnostic classification of the electrocardiogram are described: a heuristic one and a statistical one. In the heuristic approach, the cardiologist provides the knowledge to construct a classifier, usually a decision tree. In the statistical approach, probability densities of diagnostic features are estimated from a learning set of ECGs and multivariate techniques are used to attain diagnostic classification. The relative merits of both approaches with respect to criteria selection, comprehensibility, flexibility, combined diseases, and performance are described. Optimization of heuristic classifiers is discussed. It is concluded that heuristic classifiers are more comprehensible than statistical ones; encounter less difficulties in dealing with combined categories; are flexible in the sense that new categories may readily be added or that existing ones may be refined stepwise. Statistical classifiers, on the other hand, are more easily adapted to another operating environment and require less involvement of cardiologists. Further research is needed to establish differences in performance between both methods. In relation to performance testing the issue is raised whether the ECG should be classified using as much prior information as possible, or whether it should be classified on itself, explicitly discarding information other than age and sex, while only afterwards other information will be used to reach a final diagnosis. Consequences of taking one of both positions are discussed.

Algorithms↗
PubMed1995

Gene therapy for human liver disease.

Investigators working in the area of gene therapy believe the potential for advances in all medical disciplines is enormous. It is humbling, however to appreciate how far we need to go, as the field is truly in its infancy. Gene transfer technologies currently under evaluation in clinical trials have major limitations. Vector systems used in the clinics by the year 2000 probably have yet to be discovered. An additional lesson learned is that efforts at gene therapy are hampered by a lack of knowledge of the basic biology of the target organ and pathogenesis of the underlying disease. Successful gene therapy programs will critically evaluate the field and through fundamental research move steadily forward toward the long-term goal of truly effective therapy for a wide spectrum of disease. In the near future, two liver diseases are the most likely to be treated with gene therapy. The evaluation of patients with familial hypercholesterolemia is ongoing, and once approved, more candidates will be enrolled for therapy. Progress also has been made in creating vectors for the treatment of ornithine transcarbamylase deficiency. It remains to be seen whether adenoviruses or retroviruses will be used first in attempts to control this disease. Although the inflammatory response noted with current recombinant viruses is a formidable problem, the efficiency of gene transfer into the liver with these vectors makes continued study worthwhile.

Adenoviridae↗
PubMed1998

On the matter of rules. Past-tense formation and its significance for cognitive neuroscience.

If neuronal models are successful, they will account for specifically human complex behaviours. Most of these behaviours can be described as governed by rules. In recent years, much effort has been spent to elucidate the neuronal basis of rules, and many researchers have focussed on modelling rules and regularities underlying language, particularly those relevant for past-tense formation. After introducing problems posed by past-tense formation, important aspects of recent controversies between connectionists and linguists concerning the nature of rules will be reviewed and analysed on the basis of elementary simulations. It is argued that modular networks with varying connection probabilities between their layers would be ideal for modelling learning and processing of past-tense formation. The motivation for postulating such networks comes from neurobiological models of language and from neuroanatomical data about cortico-cortical connectivity. Furthermore, such modular networks may explain double dissociations of regular and irregular past-tense formation in neurological patients, as reported in recent neuropsychological publications. It is concluded that past-tense formation does not pose problems to pattern associators, given that some structure is built into the network which approximates wirings in the human cortex.

Brain↗
PubMed2000

The neuroanatomical correlates of route learning impairment.

Recent functional imaging studies of topographical learning point to the participation of a large network of cortical and subcortical regions. Nevertheless, areas which are crucial remain poorly specified due to the absence of group studies of subjects with focal lesions distributed throughout the brain. We assessed the ability of 127 subjects with stable, focal lesions to learn a complex real-life route, a critical aspect of topographical functioning. Results indicated that impairment in route learning was highly associated with damage to medial occipital and posterior parahippocampal cortices in either hemisphere, the right hippocampus, and the right inferotemporal region. Impairment was seen among 86% of the subjects with damage to any these regions, in contrast to impairment among 31% of subjects with lesions in other regions. The importance of medial occipitotemporal cortices bilaterally and right inferotemporal cortex likely reflects the critical role of the ability to quickly and accurately perceive and learn multiple topographical scenes. The importance of the right (and probably left) posterior parahippocampal gyrus and of the right hippocampus likely reflects their critical, distinctive roles forming an integrated representation of the extended topographical environment (i.e., the appearance of places and spatial relationships between specific places), and consolidating that representation into multifaceted contextual knowledge of the environment.

Brain Mapping↗
PubMed2003

Comparison of implicit and explicit learning processes in a probabilistic task.

This experiment compared the performance with explicit (rule-application and rule-discovery) and implicit (nonrule-instructed) learning approaches on the performance of a probabilistic video game task requiring fine motor control. The task required visual tracking of a small ball of light and "catching" it by means of joystick manipulation. A general pattern of improvement with practice occurred for all conditions. All conditions showed use of predictive relations among stimulus events. However, task performance of the rule-application and rule-discovery conditions were inferior to the nonrule-instructed implicit condition, particularly during the early phases of rule acquisition and application. This pattern strongly suggests substantial performance costs associated with attempting to discover or apply probabilistic rules. Decrements are likely due to increased cognitive demands associated with attempting to remember and strategically apply provided probability rules or attempting to discover and apply potentially important and useful probability information from a complex visual display.

Adult↗
PubMed1991

Disaster management. Lessons learned.

Our experiences have taught us that practice makes perfect and that it probably is unreasonable to expect everything to be orderly, sane, and appropriate during disaster management. The best we can hope for probably is controlled chaos. We do believe that we have generated an improved plan, that the plan is known, and that it is being revised continuously. We can no longer rely on our goodwill and good intentions to manage mass casualties in a disaster. There are too many factors that can reduce our ability to provide medical care in this situation. Hospital planning is essential. The hospital should be represented on the emergency preparedness committee so it is knowledgeable about the various plans throughout the city. Each plan must be practiced and critiqued to identify potential problems. Hospital staff must be kept current on the various plans to understand the communication, authority, responsibility, security, and medical control for each plan. We have instituted a video program outlining the various tasks for each hospital department for each disaster plan. This format allows the personnel in these departments to review their responsibilities continually in a concise manner and allows practice of disaster preparedness without implementing an entire disaster drill. Table 1 provides a quick review of the areas and questions we found to be problems when implementing our disaster plan.

Accidents, Aviation↗
PubMed2006

Neuropsychological assessment with the Visual Gestalt Test: psychometric properties and differential diagnostic probabilities.

The Visual Gestalt Test is a neuropsychological instrument developed for evaluation of learning and memory of visuo-spatial material. A revised strategy of scoring has motivated the present study, where data from 153 normal persons, 99 epilepsy patients, and 24 depressed patients are presented and compared. The Visual Gestalt Test is observed to discriminate between normal and diagnosed groups in several ways. Additionally it is found to discriminate between depressed and brain damage subgroups of patients. Data are presented in order to supplement previously published ways of scoring and norms. Practical guidelines for the clinical applications of the test are suggested as perspectives.

Adolescent↗
PubMed2002

A new area in the human brain associated with learning and memory: immunohistochemical and functional MRI analysis.

Previous studies identified a new brain area, the marginal division (MrD), at the caudomedial border of the neostriatum in the brain of the rat, cat and monkey. The MrD was distinguishable from the rest of the striatum by the presence of spindle-shaped neurons, specific connections, and dense immunoreactivity for neuropeptides and monoamines in fibers, terminals and neuronal somata. Behavioral testing demonstrated that the MrD contributes to learning and memory in the rat. In the present study, the structure and the function of the MrD were investigated in the human brain. The presence of spindle-shaped neurons and the distribution of neurotransmitters in the MrD were evaluated by immunocytochemical methods. The function of the MrD was identified with functional magnetic resonance imaging (fMRI) of healthy volunteers tested with an auditory digital working memory task. Highly active areas were observed in the prefrontal cortex and MrD with left sided predominance during performance of the task, but other parts of the neostriatum were not excited and the MrD was not activated in a control test of non-working memory. The results of the present investigation therefore indicate the existence of a new area associated with learning and memory function in the human brain. The MrD probably plays an important role in the execution of digital working memory and appears to link the limbic system and the basal nucleus of Meynert. The MrD may also be involved in the mechanism of Alzheimer's disease.

Adult↗
PubMed1998

Approximate Statistical Tests for Comparing Supervised Classification Learning Algorithms.

This article reviews five approximate statistical tests for determining whether one learning algorithm outperforms another on a particular learning task. These tests are compared experimentally to determine their probability of incorrectly detecting a difference when no difference exists (type I error). Two widely used statistical tests are shown to have high probability of type I error in certain situations and should never be used: a test for difference of two proportions and a paired-differences t test based on taking several random train-test splits. A third test, a paired-differences t test based on 10-fold cross-validation, exhibits somewhat elevated probability of type I error. A fourth test, McNemar's test, is shown to have low type I error. The fifth test is a new test, 5 x 2 cv, based on five iterations of twofold cross-validation. Experiments show that this test also has acceptable type I error. The article also measures the power (ability to detect algorithm differences when they do exist) of these tests. The cross-validated t test is the most powerful. The 5 x 2 cv test is shown to be slightly more powerful than McNemar's test. The choice of the best test is determined by the computational cost of running the learning algorithm. For algorithms that can be executed only once, McNemar's test is the only test with acceptable type I error. For algorithms that can be executed 10 times, the 5 x 2 cv test is recommended, because it is slightly more powerful and because it directly measures variation due to the choice of training set.

Journal Article↗