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PubMed1992

The spatial and temporal characteristics of perceiving 3-D structure from motion.

In four experiments, a scalar judgment of perceived depth was used to examine the spatial and temporal characteristics of the perceptual buildup of three-dimensional (3-D) structure from optical motion as a function of the depth in the simulated object, the speed of motion, the number of elements defining the object, the smoothness of the optic flow field, and the type of motion. In most of the experiments, the objects were polar projections of simulated half-ellipsoids undergoing a curvilinear translation about the screen center. It was found that the buildup of 3-D structure was: (1) jointly dependent on the speed at which an object moved and on the range through which the object moved; (2) more rapid for deep simulated objects than for shallow objects; (3) unaffected by the number of points defining the object, including the maximum apparent depth within each simulated object-depth condition; (4) not disrupted by nonsmooth optic flow fields; and (5) more rapid for rotating objects than for curvilinearly translating objects.

Adult↗

PubMed1993

A 10-year experience with postpump chorea.

Postpump chorea (PPC) is the development of choreoathetoid movements within 2 weeks following cardiopulmonary bypass. Over a 10-year period, 668 children underwent open cardiac surgery, of whom 8 (1.2%) developed PPC. Age at surgery ranged from 8 to 34 months. The onset of chorea was 3 to 12 days following surgery. Computed tomography and magnetic resonance imaging showed atrophy but no focal lesions. Cerebral positron emission tomography using [18F]fluorodeoxyglucose in a patient following 12 months of chorea showed patchy areas of decreased glucose metabolism. None of the patients were developmentally normal 22 to 130 months following surgery. Three patients have had transient and 5 have persistent chorea. Neurological deficits ranged from a mild learning disability to progressive hypotonia and obtundation ending in death. One of 4 patients who received haloperidol had a decrease in the severity of chorea. We compared PPC patients with 39 randomly selected controls. During surgery, affected patients spent significantly more time on pump and at temperatures under 36 degrees C, were cooled to lower temperatures than controls, and were more likely to have had a circulatory arrest. One patient developed chorea without a history of circulatory arrest. We conclude that (1) there is a strong association between PPC, deep hypothermia, and circulatory arrest, (2) absence of characteristic macroscopic changes suggests a biochemical or microembolic etiology in some cases, (3) chorea is frequently associated with developmental delay, and (4) the prognosis for complete resolution of chorea is guarded.

Brain↗

PubMedDate not supplied

Pattern in the cortical distribution of prefrontally directed neurons with divergent axons in the rhesus monkey.

Neurons with divergent branched axons have been noted in several structures, but their organization across cortical systems, cortical types, or cortical layers is not known. The above questions were addressed with the aid of multiple fluorescent retrograde tracers injected in one hemisphere of the prefrontal cortex of rhesus monkeys. The prefrontal cortex is well suited for this study because it receives input from diverse cortical systems. A small number of neurons (integral of 1%) that projected to two different ipsilateral prefrontal sites, and were thus double-labeled, were noted in prefrontal, premotor, visual, somatosensory, auditory, and parietotemporal association cortices, suggesting that this form of projection is general within the cortex. However, double-labeled neurons were noted in significantly higher numbers in transitional than in eulaminate areas. Moreover, neurons with divergent axons were more prevalent in the deep cortical layers than in the upper layers in both transitional and eulaminate areas. Although neurons with divergent axons constitute a small population of those that issue corticocortical projections in several adult mammalian species, they are preponderant in the primary sensory cortices of the fetal or neonatal stages. Transitional areas, which include a higher proportion of neurons with divergent axons, may retain some features observed in development to a greater extent than eulaminate sensory areas. This could help explain the great plasticity of transitional areas and their involvement in learning and memory, and also their preferential vulnerability in several neurologic disorders such as Alzheimer's disease and epilepsy.

Animals↗

PubMed1999

Heritable coagulopathies in pregnancy.

UNLABELLED: Heritable coagulopathies are leading causes of maternal thromboembolism and are associated with an increased risk of maternal and perinatal morbidity and mortality. The most common of these disorders are antithrombin III deficiency, protein C deficiency, protein S deficiency, activated protein C resistance resulting from the factor V Leiden mutation, elevated prothrombin activity associated with a mutation in the prothrombin gene, and hyperhomocystinemia. The maternal risk of a thromboembolic episode is increased by a factor of eight in the presence of any of these heritable states. In addition, the relative risk for a stillbirth in the presence of one of these disorders is 3.6. These conditions are also associated with intrauterine growth retardation and preeclampsia. Proper management of heritable coagulopathies during pregnancy is essential to reduce the risk of these serious sequelae. Patients with newly diagnosed deep-vein thromboses or pulmonary emboli should be treated with therapeutic levels of unfractionated or low molecular weight heparin, followed by subsequent prophylactic heparin therapy. All patients with a history of thromboembolism before pregnancy or evidence of any of these coagulopathies may be offered prophylactic therapy with low molecular weight heparin. Patients with antithrombin III deficiency should receive full therapeutic heparin therapy for the entire pregnancy, irrespective of their thromboembolic history. Postpartum therapy with either heparin or warfarin is required in all cases. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians LEARNING OBJECTIVES: After completion of this article, the reader will be able to describe the various heritable coagulopathies that can complicate pregnancy, to state the potential adverse effects of heritable coagulopathies in pregnancy, and to explain the management of heritable coagulopathies during pregnancy.

Activated Protein C Resistance↗

PubMed1975

Nerve distribution in the metacarpus and front digit of the horse.

The nerve distribution to the digit of the horse was studied with the compound microscope in serial transverse sections of fetal limbs and plotted on life-size outlines of the horse's foot. It was learned that there is much variation in the topography of the branches of the principal nerves. There is no mirror-image nerve distribution on the 2 sides of the foot. The dorsal branch of the ulnar nerve does not extend below the fetlock. The communication between the palmar metacarpal nerves and branches of the dorsal branch of the digital nerves is only a crossing of nerves without exchange of fibers. The palmar metacarpal nerves usually do not innervate structures distal to the pastern joint. The innervation of the deep structures of the equine foot was tabulated.

Animals↗

PubMedDate not supplied

[NMDA-dependent and NMDA-independent neuronal processes in the cat motor cortex, disinhibited by bicuculline, during forepaw placement conditioning].

Neuronal activity associated with a conditioned forepaw placing reaction was recorded in the cat's motor cortex locally disinhibited by bicuculline spontaneously diffused from the recording pipette. Electrical stimulation of the parieral cortex (area 5) with 3-5 pulses was used as a conditioned stimulus. In both naive and trained cats, adding of APV (NMDA receptor blocker) led to disappearance of the late (30-120 ms) secondary excitatory responses from the pattern of the neuronal reaction to the parietal stimulation recorded in the motor cortex. At the same time, the APV administration did not change the excitatory reactions (recorded, predominantly, in the deep cortical layers) time-locked to the execution of the conditioned movement. The conditioning resulted in a statistically significant increase in the amplitude and duration of the late secondary responses as well as in a shortening of their latency. In some cases (after a long period of training), the late secondary responses to the conditioned stimulus transformed into paroxysmal epileptiform bursts. A hypothesis is discussed that the increase in synaptic strength of the backward horizontal collaterals of layer-II/III pyramidal neurons is responsible for the learning-related changes in the neuronal reactions in the disinhibited motor cortex.

Animals↗

PubMed1995

Advances in antithrombotic therapy: novel agents.

Most of the clinical evaluation of the direct thrombin inhibitors has been in coronary artery disease. The recent clinical reports suggest that there is a narrower window of safety with recombinant hirudin than initially thought particularly when it is used in conjunction with thrombolytic agents and aspirin in acute myocardial infarction. The efficacy data, however, indicate that the direct thrombin inhibitors have great potential particularly in the initial management of patients with acute unstable angina and non-Q-wave infarction. There is much to learn regarding the mechanism of action, optimal dose, and optimal concomitant therapy in the use of direct thrombin inhibitors in the management of acute coronary ischaemia; and since hirudin and other direct thrombin inhibitors have so much potential in the management of acute coronary ischaemia, it is critical that dose-finding studies be performed to determine safe regimens of these agents to allow their evaluation in large-scale trials with important clinical outcomes. The direct thrombin inhibitors have also shown to have promise in the prevention of deep vein thrombosis in high-risk surgical patients. There is limited clinical data on the other novel anticoagulants which are currently being developed.

Angina, Unstable↗

PubMed2004

Individual coping characteristics, rearing conditions and behavioural flexibility in pigs.

Several studies suggest that classification of piglets early in life based on the degree of resistance they display in a so-called Backtest may be indicative of their coping style at a later age. In the present study behavioural flexibility was investigated in pigs diverging for Backtest response and housing environment during rearing. Pigs were housed either without a rooting substrate (barren housing, B) or in identical pens enriched with deep straw bedding (enriched housing, E) from birth. During the suckling period piglets were subjected to the Backtest. Each piglet was restrained on its back for 1 min and the resistance (i.e. number of escape attempts) was scored. Pigs classified as 'high-resisting' (HR) or as 'low-resisting' (LR) were subjected to a simple (left/right) spatial discrimination (T-maze) task at 8 weeks of age. The effect of a single, subtle intramaze change was determined after acquisition of the task. In addition, pigs were subjected to reversal learning to assess their ability to modulate established behaviour patterns. Housing and its interaction with Backtest classification influenced the behavioural response to the intramaze change: E pigs were considerably more distracted than B pigs. Housing condition affected LR pigs more than HR pigs, as indicated by the interaction effects on various recorded behaviours. These interactions indicate that behavioural responding of pigs with diverging coping characteristics cannot simply be generalised across rearing conditions. Furthermore, HR pigs were less successful in reversal learning than LR pigs, suggesting that they have a higher propensity to develop inflexible behavioural routines.

Adaptation, Psychological↗

PubMed2004

Direction-selective visual responses in macaque superior colliculus induced by behavioral training.

In a previous report, we described a heretofore undetected population of neurons in the intermediate and deep layers of the monkey superior colliculus (SC) that yielded directionally selective visual responses to stimuli presented within the central 4 degrees of the visual field. We observed these neurons in three monkeys that had been extensively trained to perform a visual direction discrimination task in this region of the visual field. The task required the monkeys to report the perceived direction of motion by making a saccadic eye movement to one of two targets aligned with the two possible directions of motion. We hypothesized that these neurons reflect a learned association between visual motion direction and saccade direction formed through extensive training on the direction discrimination task. We tested this hypothesis by searching for direction-selective visual responses in two monkeys that had been trained to perform a similar motion discrimination task in which the direction of stimulus motion was dissociated from the direction of the operant saccade. Strongly directional visual responses were absent in these monkeys, consistent with the notion that extensive training can induce highly specific visual responses in a subpopulation of SC neurons.

Animals↗

PubMed2005

A survey of training and practice patterns of massage therapists in two US states.

BACKGROUND: Despite the growing popularity of therapeutic massage in the US, little is known about the training or practice characteristics of massage therapists. The objective of this study was to describe these characteristics. METHODS: As part of a study of random samples of complementary and alternative medicine (CAM) practitioners, we interviewed 226 massage therapists licensed in Connecticut and Washington state by telephone in 1998 and 1999 (85% of those contacted) and then asked a sample of them to record information on 20 consecutive visits to their practices (total of 2005 consecutive visits). RESULTS: Most massage therapists were women (85%), white (95%), and had completed some continuing education training (79% in Connecticut and 52% in Washington). They treated a limited number of conditions, most commonly musculoskeletal (59% and 63%) (especially back, neck, and shoulder problems), wellness care (20% and 19%), and psychological complaints (9% and 6%) (especially anxiety and depression). Practitioners commonly used one or more assessment techniques (67% and 74%) and gave a massage emphasizing Swedish (81% and 77%), deep tissue (63% and 65%), and trigger/pressure point techniques (52% and 46%). Self-care recommendations, including increasing water intake, body awareness, and specific forms of movement, were made as part of more than 80% of visits. Although most patients self-referred to massage, more than one-quarter were receiving concomitant care for the same problem from a physician. Massage therapists rarely communicated with these physicians. CONCLUSION: This study provides new information about licensed massage therapists that should be useful to physicians and other healthcare providers interested in learning about massage therapy in order to advise their patients about this popular CAM therapy.

Adult↗

PubMed2006

Ideas as art. Interview by Dane Cutu.

Three years ago, consultants Laurence Prusak and Thomas H. Davenport asked prominent management thinkers to name their gurus and reported the results in HBR. James G. March appeared on more lists than any other person except Peter Drucker. A professor emeritus in management, sociology, political science, and education at Stanford University, March has taught courses in subjects as diverse as organizational psychology, behavioral economics, leadership, rules for killing people, friendship, computer simulation, and statistics. He is perhaps best known for his pioneering contributions to organization and management theory. March's accomplishments in that field, and in many others, have conferred on him an almost unprecedented reputation as a rigorous scholar and a deep source of wisdom. As University of Chicago professor John Padgett wrote in the journal Contemporary Sociology, "March's influence, unlike that of any of his peers, is not limited to any possible subset of the social science disciplines; it is pervasive." March approaches thought aesthetically; he cares that ideas have "some form of elegance or grace or surprise." His poetic sensibility can be felt in the metaphors he has created over the years--the "garbage can theory" of organizational choice, for instance, and the "hot-stove effect" in learning. In this edited interview with HBR senior editor Diane Coutu, March shares his thinking on aesthetics, leadership, the role of folly, and the irrelevance of relevance when it comes to the pursuit of ideas. He also comments on the fundamental differences between academic and experiential knowledge, underscoring the need for both.

Commerce↗

PubMed1989

[Late-infantile form galactosialidosis with psychomotor retardation and spastic paraparesis].

We described a case of late-infantile form of galactosialidosis. This male patient was a product of normal pregnancy. His parents were first cousins. He first sat at eight months, walked and talked at two years of age. His gait gradually became unsteady and he was diagnosed as spastic paraparesis at the age of five years. Abnormally slow learning was first pointed out at seven years of age. At the age of nine years, we evaluated him in detail at our university hospital. Physical examination revealed a short stature for his age, slightly coarse face, short neck, funnel chest, genu, pes and hallucis valgus. Corneal clouding, hernia and angiokeratoma were not found. Neurological examination showed mental retardation, bilateral optic atrophy without cherry-red spots, and spastic and slightly ataxic gait. Slight muscular atrophy with weakness was also seen in the extremities, more remarkable in the lower limbs. Deep tendon reflexes were hyperactive with bilateral ankle clonus and no extensor planter response. Routine examination of blood, urine and cerebrospinal fluid were normal except for approximately 10% lymphocytes containing cytoplasmic vacuoles. X-ray films of the backbone exhibited vertebral plana with anterior breaking at the second lumbar vertebra level. The electroencephalography showed the multiple spike and slow wave complexes. Brain CT depicted the atrophy of cerebellum. The activities of sialidase and beta-galactosidase were markedly reduced in white blood cells and cultured skin fibroblasts in this patient. His urinary excretion of sialyloligosaccharides increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate Metabolism, Inborn Errors↗

PubMed2006

Cognitive sequelae of subthalamic nucleus deep brain stimulation in Parkinson's disease: a meta-analysis.

BACKGROUND: Deep brain stimulation of the subthalamic nucleus (STN DBS) is an increasingly common treatment for Parkinson's disease. Qualitative reviews have concluded that diminished verbal fluency is common after STN DBS, but that changes in global cognitive abilities, attention, executive functions, and memory are only inconsistently observed and, when present, often nominal or transient. We did a quantitative meta-analysis to improve understanding of the variability and clinical significance of cognitive dysfunction after STN DBS. METHODS: We searched MedLine, PsycLIT, and ISI Web of Science electronic databases for articles published between 1990 and 2006, and extracted information about number of patients, exclusion criteria, confirmation of target by microelectrode recording, verification of electrode placement via radiographic means, stimulation parameters, assessment time points, assessment measures, whether patients were on levodopa or dopaminomimetics, and summary statistics needed for computation of effect sizes. We used the random-effects meta-analytical model to assess continuous outcomes before and after STN DBS. FINDINGS: Of 40 neuropsychological studies identified, 28 cohort studies (including 612 patients) were eligible for inclusion in the meta-analysis. After adjusting for heterogeneity of variance in study effect sizes, the random effects meta-analysis revealed significant, albeit small, declines in executive functions and verbal learning and memory. Moderate declines were only reported in semantic (Cohen's d 0.73) and phonemic verbal fluency (0.51). Changes in verbal fluency were not related to patient age, disease duration, stimulation parameters, or change in dopaminomimetic dose after surgery. INTERPRETATION: STN DBS, in selected patients, seems relatively safe from a cognitive standpoint. However, difficulty in identification of factors underlying changes in verbal fluency draws attention to the need for uniform and detailed reporting of patient selection, demographic, disease, treatment, surgical, stimulation, and clinical outcome parameters.

Chi-Square Distribution↗

PubMed2001

Neurodevelopmental outcome related to cerebral risk factors in children after neonatal arterial switch operation.

BACKGROUND: Neurodevelopmental outcome after neonatal arterial switch operation for complete transposition of the great arteries is an important topic needing prospective assessment. METHODS: A group of 33 unselected children (3.0 to 4.6 years) operated on as neonates with combined deep hypothermic circulatory arrest and low flow cardiopulmonary bypass and a control group of 32 age-matched healthy children (3.0 to 4.8 years) underwent evaluation of socioeconomic and clinical neurological status and a standardized test comprising all areas of child development. Results of patients were related to those of the control group, to population norms, and to preoperative, perioperative, and postoperative cerebral risk factors. RESULTS: Clinical neurological status was normal in 26 patients (78.8%) and reduced in 7 (21.2%). Complete developmental score and the subscores for motor function, visual perception, learning and memory, cognitive function, language, and socioemotional functions were not different compared to population norms. Compared to the patients, the children of the control group scored higher on tests of complete development, cognition, and language, but also on socioeconomic status. Complete developmental score and the scores for motor, cognitive, and language functions were weakly inversely related to the duration of circulatory arrest, but not to the duration of bypass. Cerebral risk factors such as serum levels of the neuron-specific enolase, perinatal acidosis, perinatal asphyxia, peri- and postoperative cardiocirculatory insufficiency, or clinical seizures were not correlated to the test results. CONCLUSIONS: Neonatal arterial switch operation with combined circulatory arrest and low flow bypass is associated with neurological impairment, but not with reduced development as assessed by formal testing of motor, cognitive, language, and behavioral functions. Perioperative serum level of the neuron-specific enolase is not a valid marker for later developmental impairment.

Arteries↗

PubMed2001

Risk and the neoliberal state: why post-Mitch lessons didn't reduce El Salvador's earthquake losses.

Although El Salvador suffered light losses from Hurricane Mitch in 1998, it benefited from the increased international aid and encouragement for advance planning, especially mitigation and prevention interventions. Thus, one would have supposed, El Salvador would have been in a very advantageous position, able more easily than its economically crippled neighbours, Honduras and Nicaragua, to implement the 'lessons of Mitch'. A review of the recovery plan tabled by the El Salvador government following the earthquakes of early 2001 shows that despite the rhetoric in favour of 'learning the lessons of Mitch', very little mitigation and prevention had actually been put in place between the hurricane (1998) and the earthquakes (2001). The recovery plan is analysed in terms of the degree to which it deals with root causes of disaster vulnerability, namely, the economic and political marginality of much of the population and environmental degradation. An explanation for the failure to implement mitigation and preventive actions is traced to the adherence by the government of El Salvador to an extreme form of neoliberal, free market ideology, and the deep fissures and mistrust in a country that follow a long and bloody civil war.

Disaster Planning↗

PubMed1999

Buccal fat pad pedicle flap for midface augmentation.

Midface aging is characterized by soft-tissue ptosis with loss of cheek projection. Subperiosteal midface lifts may reposition the soft-tissue mounds and improve the tear trough, but may not fill the lateral cheeks in patients with significant jowls or poor bony support. Correction with alloplastic implants is helpful, but may not be accepted by many patients. During subperiosteal midface lifts, the author often excises Bichat's fat pad to decrease the jowl and to diminish face fullness. He has modified this approach and used a vascularized Bichat's fat flap to aid lateral cheek projection while still improving lower face fullness and the jowl. For the last 4 years, close to 150 patients undergoing subperiosteal midface lifts have had vascularized Bichat's fat pad flaps. The jowls were marked preoperatively. All patients had complete cheek undermining either through a buccal sulcus incision or through a crow's-foot incision, or through a muscle-sparing limited lower blepharoplasty incision. Bichat's fat pad is identified in its pocket medial to the masseter tendon. Mobilization of Bichat's fat pad is done by blunt dissection, preserving its thin fascial envelope. The "hernial saclike" pocket, excluding Stensen's duct and the buccal branches of the facial nerve, is identified and protected. Suspension is accomplished by fixation with 3-0 polydioxanone sutures either to the temporalis fascia (via the temporal incisions), to the arcus marginalis, or to the suborbicularis oculi fat pad. Fixation technique is dependent on where the fat pad is needed and the surgeon's preference. Fat pad repositioning is accomplished with a minor learning curve. The most common problems are tearing of the fat pad during fixation and temporary numbness of the long buccal nerve. Attention to leaving the capsule intact and gentle handling is essential to fixation. Nevertheless, in some patients with poor-quality fat pads, fixation is extremely difficult. Four-year results have been excellent. Further studies with magnetic resonance imaging of postoperative patients are necessary to assess longevity. Bichat's fat pad provides autologous vascularized tissue for midface fill. Placement may be lateral for cheek augmentation or medial for deep nasolabial folds. Jowl improvement also occurs with the removal of Bichat's fat pad from its pocket.

Adipose Tissue↗

PubMed2003

A nonparametric item analysis of a selected item subset of the learning process questionnaire.

BACKGROUND: Although there have been numerous studies conducted on the psychometric properties of Biggs' Learning Process Questionnaire (LPQ), these have involved the use of traditional omnibus measures of scale quality such as corrected item total correlations, internal consistency estimates of reliability, and factor analysis. However, these omnibus measures of scale quality are sample dependent and fail to model item responses as a function of trait level. And since the item trait relationship is typically nonlinear, traditional factor analytic methods are inappropriate. AIMS: The purpose of this study was to identify a unidimensional subset of LPQ items and examine the effectiveness of these items and their options in discriminating between changes in the underlying trait level. In addition to assessing item quality, we were interested in assessing overall scale quality with non-sample dependent measures. METHOD: The sample was split into two nearly equal halves, and a undimensional subset of items was identified in one of these samples and cross-validated in the other. The nonlinear relationship between the probability of endorsing an item option and the underlying trait level was modelled using a nonparametric latent trait technique known as kernel smoothing and implemented with the program TestGraf. After item and scale quality were established, maximum likelihood estimates of participants' trait level were obtained and used to examine grade and gender differences. RESULTS: A undimensional subset of 16 deep and achieving items was identified. Slightly more than half of these items needed some of their options combined so that the probability of endorsing an item option as a function of increasing trait level corresponded to the ideal rank ordering of the item options. With this adjustment, scale quality as measured by the information function and standard error function was found to be good. However, no statistically significant gender differences were observed and, although statistically significant grade differences were observed, they were not substantively meaningful. CONCLUSIONS: The use of nonparametric kernel-smoothing techniques is advocated over parametric latent trait methods for the analysis of attitudinal and psychological measures involving polychotomous ordered-response categories. It is also suggested that latent trait methods are more appropriate than traditional test-based measures for studying differential item functioning both within and between cultures. Nonparametric kernel-smoothing techniques hold particular promise in identifying and understanding cross-cultural differences in student approaches to learning at both the item and scale level.

Achievement↗

PubMed1981

Crawling-onset age predicts visual cliff avoidance in infants.

Two experiments are reported that tested the effects of crawling-onset age, the amount of crawling experience, and testing age on avoidance of the deep side of a visual cliff apparatus by human infants. In Experiment 1, 49 infants ranging in age from 7 to 13 mo. were tested on the visual cliff after 1 or 2 mo. of crawling experience. Discriminant analysis revealed that crawling-onset age, and not crawling experience, discriminated between those infants who crossed and those infants who avoided the apparent drop-off. Infants who crossed the deep side were infants with an early crawling-onset age. In Experiment 2, 40 infants were tested on a visual cliff apparatus, half at 9 and half at 12 mo. of age. Discriminant analysis again found that crawling-onset age discriminated between infants who crossed the infants who would not cross the deep side, whereas testing age alone did not. These results call into question the idea that experience crawling is critical in inducing visually guided avoidance behavior in infants. It is argued that the crawling-onset age effect occurs because crawling during the tactile phase of infancy interferes with later visual control of locomotion.

Age Factors↗