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Biomedical subjects

B Dan

Publications and source records attributed to B Dan.

At least 73 records · Page 4Linked to original sources
PubMed1999

Kinematics invariance in multi-directional complex movements in free space: effect of changing initial direction.

We investigated in normal human subjects the effect of changing the initial direction on the kinematic properties of figure '8' movement performed as fast as possible by the right arm extended in free space. To this end, the motion of the index finger was monitored by the ELITE system. The figure '8' movement was characterized by a complex tangential velocity profile (Vt) presenting 5 bell-shaped components. It was found that the temporal segmentation following Vt was not significantly different, whatever the initial direction of the movement. The decomposition of Vt into different velocity profiles with respect to vertical (3 phases, Iy-IIIy) and horizontal (5 phases, Iz-Vz) directions showed a significant relationship between the amplitude and the maximal velocity for all the different phases (except the IIy phase), which demonstrated a good conservation of the Isochrony Principle. However, we showed that the transition between the clockwise and counter-clockwise loop (inflection point) induced greater variability in the vertical velocity profile than in the horizontal one. Moreover, some parameters such as the maximal velocity of Iy and the movement amplitude of the last phases (IIIy and Vz) showed significant changes depending on the initial direction. A highly significant positive correlation was observed between the instantaneous curvature and angular velocity. This was expressed by a power law similar to that previously describe for other types of movement. Furthermore, it was found that this covariation between geometrical and kinematic properties of the trajectory is not dependent on the initial direction of movement. In conclusion, these results support the idea that the fast execution in different directions of a figure '8' movement is mainly controlled by two types of invariant commands. The first one is reflected in the 2/3 power law between angular velocity and curvature and the second one is represented by a segmented tangential velocity profile.

Adult↗
PubMed1999

Magnetic resonance imaging cranial and cerebral dimensions: is there a relationship with Chiari I malformation? A preliminary report in children.

The pathogenesis of idiopathic Chiari I malformation (CM I) remains poorly understood, although it is thought to be due to disproportion between hindbrain structures and the posterior fossa (PF) dimensions. This study was undertaken to determine whether CM I and its possible complications are associated with disproportion between cranial and cerebral dimensions. Surface of the vermis, PF and supratentorial (ST) area were measured on magnetic resonance imaging midsagittal sections and were correlated with age in 19 children with CM I and 43 controls. The ratio of the PF/ST area and of the vermis/PF area were also plotted against age in the two groups and against length of the tonsils herniation in the CM I malformation group. Only the vermis midsagittal area and the vermis/PF ratio were found to be significantly higher in CM I malformation subjects. There was no correlation between the length of tonsils herniation and the vermis/PF area or the PF/ST area ratio in this group. The most severe complications (large syrinx and hydrocephalus) were not associated with particular measurements or calculated ratios in the children with CM I malformation except for the relatively small PF area in a neonate. We conclude that factors responsible for the appearance of clinical signs remain largely unknown. In particular, cranial and brain measurements alone do not seem to predict complications or unfavourable clinical evolution.

Age Factors↗
PubMed1999

Dopey's seizure.

Angelman syndrome is a neurogenetic condition namely characterized by developmental delay, virtual absence of expressive verbal language, peculiar organization of movement, seizures and happy demeanor. This syndrome has been recognized since 1965, but it seems that Walt Disney presented an original depiction of it in his first full-length animated film, including myoclonic jerks and an apparently generalized tonic-clonic seizure.

Angelman Syndrome↗
PubMed1999

Magnetic resonance imaging and angiography in cerebral fungal vasculitis.

We report on an 11-year old girl treated for leukemia who developed infarcts in the right lentiform nucleus and temporal lobe. Magnetic resonance angiography (MRA) showed mild intraluminal irregularities in the right carotid syphon and stenosis of the right proximal middle cerebral artery, suggesting vasculitis. Magnetic resonance imaging (MRI) follow-up showed evolution of the initial infarct into an abscess. Stereotactic biopsy disclosed filaments of aspergillus. This report emphasizes the fact that cerebral aspergillosis should be considered if MRA and MRI are indicative of vasculitis and cerebral infarction in immunosuppressed children.

Aspergillosis↗
PubMed1998

Multi-joint coordination strategies for straightening up movement in humans.

Complex movement execution theoretically involves numerous biomechanical degrees of freedom, leading to the concept of redundancy. The kinematics and kinetics of rapid straightening up movement from the squatting position were analysed with the optoelectronic ELITE system in 14 subjects. We found multiple acceleration and deceleration peaks for the hip, knee and ankle joints during the early extension phase of the movement. In order to test the temporal coordination between the angular acceleration of these joints, conjugate crosscorrelation functions (CCF) between each set of two variables were calculated. We found a bimodal distribution of the maximum CCF in positive and negative values suggesting the existence of two distinct strategies, the in-phase and the out-of-phase strategy for each pair of joints. The hip and knee coordination strategies (in- or out-of-phase) were well conserved in each subject for repetitive movements. Combination of joint pair strategies was more reproducible for the hip-knee/knee-ankle pair than for the other combinations, suggesting that the straightening up strategies are organised around the knee. We conclude that mastering of the redundancy problem can be realised by using coordination strategies characterised by opposed joint acceleration patterns.

Acceleration↗
PubMed1998

Divergent responses to fluoxetine from two compulsive, food-related conditions: bulimia nervosa and compulsive water drinking.

BACKGROUND: The association of compulsive water drinking with bulimia nervosa is rarely encountered. Nevertheless similar behavior patterns could involve a common pathophysiological mechanism. METHODS: A case report with the association of those two disorders is described. Treatment with fluoxetine was introduced to alleviate the compulsive aspects of those disorders. RESULTS: Fluoxetine had a positive effect on bulimia nervosa but none on compulsive water drinking. CONCLUSIONS: The different response to pharmacologic treatment could mean that bulimia nervosa and compulsive water drinking are based on different physiological mechanisms.

Adult↗
PubMed1998

Dacrystic seizures reconsidered.

Ictal lachrymation has not been reported in children as a main seizure manifestation. We report an infant with tuberous sclerosis who presented with seizures characterised by lachrymation without apparent emotional change associated with a left posterior temporal epileptic focus. We discuss the pathophysiological implications, and propose a clinically orientated classification of crying seizures.

Electroencephalography↗
PubMed1997

Hemorrhage in the cavum septi pellucidi in a full-term neonate.

A case of hemorrhage in the cavum septi pellucidi presenting as macrocephaly secondary to hydrocephalus in a full-term neonate is described. This condition has only been reported previously in one premature infant. This unusual location of intracranial bleeding has been demonstrated by ultrasonography and MRI. We discuss the pathophysiology.

Cerebral Hemorrhage↗
PubMed1997

Development of cardiopulmonary integration and the role of arousability from sleep.

The recent literature on cardiopulmonary integration in infants is surveyed here, focusing on arousals from sleep. Recent studies reported that the ontogenicity of cardiopulmonary integration cannot be evaluated independently from that of sleep-wake cycles. The issue is of importance for researchers and clinicians evaluating cardiorespiratory characteristics in infants. It also has significant implications in the understanding of clinical conditions, such as parasomnias, obstructive sleep apneas, or some cases of sudden infant death syndrome. The propensity to arouse can be evaluated by exposing the sleeper to awakening challenges. Arousal thresholds are determined by measuring the intensity of the stimulus needed to induce arousals. However, these studies are complicated by factors such as the scoring of the arousal responses. Another difficulty lies in the choice and modality of the arousal stimulus. Noise, gases, light, and nociceptive, mechanical, chemical, or temperature stimuli have all been used to induce arousals. Confounding factors modify the sleeper's responses to a given stimulus. Prenatal drug, alcohol, or cigarette use and the infant's age or, previous sleep deprivation also modify thresholds. Other confounding factors include time of the night, sleep stages, the sleeper's body position, and sleeping conditions. Arousal can also occur spontaneously because of endogenous stimuli. The literature surveyed here also covers such unresolved issues as the clinical significance of aborted arousals, or the mechanisms responsible for the arousal reactions.

Age Factors↗
PubMed1997

New syndrome or severe expression of Gordon syndrome? A case report.

A boy with multiple congenital anomalies including median cleft palate, bilateral hearing loss, clino- and camptodactyly, bilateral single palmar flexion creases, severe hypotonia with kyphoscoliosis and respiratory insufficiency, failure to thrive, bilateral cryptorchidism and facial dysmorphism (epicanthus, a flat nasal bridge, a small mouth, a small nose with anteverted nostrils, low-set ears, a prominent forehead, microretrognathia) is presented. His mother has a median cleft palate, bilateral hearing loss, single palmar flexion creases, and short stature. An autosomal or X-linked dominant syndrome with more severe expression in the proband than in his mother is suggested.

Abnormalities, Multiple↗
PubMed1996

Normal sleep architecture in infants and children.

Because the collection of normative sleep data in the pediatric age group largely depends on technical issues, this article discusses various aspects of sleep recordings in infants and children. Polygraphic monitoring of sleep and waking behavior contributes to a better description of maturational stages in children, from the prenatal period to the end of adolescence. This article reviews the general characteristics of normal children's sleep and the environmental factors that influence these maturational processes. The use of polygraphic recordings to identify neurological deficits and to predict behavioral and neurological outcome in infants and children, however, does not hold great promise. The importance of polysomnographic evaluation is admitted for some major clinical conditions, such as risks for abnormal breathing or narcoleptic attacks.

Adolescent↗
PubMed1992

[Fetal alcoholism syndrome: apropos of a case].

Fetal alcoholic syndrome (F.A.S.) is a well-recognized entity for over 20 years; it associates mental retardation, delayed growth and anomalies of the cranium in children born from alcoholic mothers. The syndrome has been described primarily in young children. By contrast, its evolution is not well known. We report the case of a 15-year old youngster, who exhibited the characteristic features of F.A.S. We also review the data related to the clinical and pathophysiologic aspects of the syndrome.

Adolescent↗
PubMed1992

[Fetal alcohol syndrome].

Ethanol teratogenicity manifests itself in the form of the foetal alcohol syndrome (FAS). This syndrome is characterised by growth delay, impairment of the central nervous system, and various facial dysmorphisms. We report the case of a 19 month-old boy affected by FAS. In addition to the three common features of FAS, this patient disclosed organic (digestive and cardiac) malformations and cellular chemotaxis deficiency. We have reviewed the literature to provide an update on the clinical signs of FAS. The abnormalities provoked by foetal exposure to ethanol can be very varied, none of them being specific.

Abnormalities, Multiple↗
PubMed1991

[Organic morbidity of a hospitalized psychiatric population].

In order to determine organic morbidity in psychiatry, 140 psychiatric inpatients (aged between 20 and 49) were examined. After various investigations (physical, biological, chest film, EEG, ECG), it was concluded that 52% of the patients suffer from at least one physical disease, and 23% suffer from more than one. The most frequent diseases are digestive (hepatic), respiratory and cardiovascular. The relationship between opiate addiction and stomatological, urogenital and dermatological diseases, and between alcoholism and liver diseases seems clear. It would appear that a medical approach adapted to psychiatric patients is necessary in order better to diagnose these physical diseases, and to reduce psychiatric overmorbidity, which might lead to a decrease in psychiatric excess mortality.

Adult↗
PubMed1983

The paper chase.

Explore the source record for details and available documents.

Boston↗
PubMedDate not supplied

Alcoholism and emotional reactivity: more heterogeneous film-induced emotional response in newly detoxified alcoholics compared to controls--a preliminary study.

Alcoholics are thought to be characterized by irregular emotional responses, having trouble reaching an optimal level of emotional arousal. They therefore may use alcohol to restore emotional homeostasis. This study investigated whether recently detoxified alcoholics show different emotional responses as compared to controls. Film excerpts were used to induce emotions in 14 newly detoxified alcoholics (9 men, 5 women) and matched controls in a standardized laboratory setting. Subjective emotional (questionnaires) and physiological measures were employed. Depression and cognitive deterioration were controlled. Based on subjective ratings, alcoholics displayed greater variability of emotion; they displayed also fewer or no physiological arousal changes. Subjective emotional responses were exceedingly high or low. These differences were not accounted for by depression or cognitive deterioration. We hypothesize that alcohol could be used to restore an optimal level of emotional arousal. This homeostatic function of alcohol is yet to be clearly assessed.

Adult↗