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Biomedical subjects

A Kelemen

Publications and source records attributed to A Kelemen.

At least 19 recordsLinked to original sources
PubMed2004

Intentional seizure interruption may decrease the seizure frequency in drug-resistant temporal lobe epilepsy.

We investigated the nature of preictal subjective phenomena and whether they had any effect on the seizure frequency in 95 adult patients with medial temporal lobe epilepsy. Seventy-three (77%) patients indicated that they experienced seizure-provoking factors. Ten patients (11%) had prodromas independent of auras, while auras occurred in 89%. Forty-four patients (46%) reported that that they had tried to stop their seizures in the presence of prodroma or aura and this action had resulted in success at least once. Twenty-one patients (22%) regularly tried to stop their seizures because this effort was often successful according to their interpretation. Patients who reported that they could frequently inhibit their seizures had 1.8 +/- 1.6 seizures/month, a significantly lower mean seizure frequency than those 74 patients who did not do it regularly (4.6 +/- 4.8 seizures/month, P<0.001). Patients who reported regular experience in inhibiting intentionally their seizures more often had affective (P=0.05) and vertiginous auras (P<0.01) as well as isolated auras (P<0.05). Patients who experienced provoking factors showed the same seizure frequency as those who did not. Our results suggest that intentional seizure inhibition had an impact on the severity of drug-resistant epilepsy.

Adolescent↗
PubMed2003

Mosaic mutations of the LIS1 gene cause subcortical band heterotopia.

BACKGROUND: Subcortical band heterotopia (SBH) is a neuronal migration disorder. DCX mutations are responsible for almost all familial cases, 80% of sporadic female cases, and 25% of sporadic male cases of SBH, and are associated with more severe gyral and migration abnormality over the anterior brain regions. Somatic mosaicism has previously been hypothesized in a patient with posteriorly predominant SBH and a mutation of the LIS1 gene, which is usually mutated in patients with severe lissencephaly. The authors identified mosaic mutations of LIS1 in two patients (Patients 1 and 2) with predominantly posterior SBH. METHODS: After ruling out DCX mutations, the authors performed sequencing of the LIS1 gene in lymphocyte DNA. Because sequence peaks in both patients were suggestive of mosaic mutations, they followed up with denaturing high-pressure liquid chromatography analysis on blood and hair root DNA and compared the areas of heteroduplex and homoduplex peaks. A third patient showing the same mutation as Patient 2 but with no evidence of mosaicism was used for comparing the phenotype of mosaic vs full mutation. RESULTS: The two patients with posterior SBH harbored a missense (Arg241Pro) and a nonsense (R8X) mosaic mutation of LIS1. The rate of mosaicism in Patient 1 was 18% in the blood and 21% in the hair roots, whereas in Patient 2 it was 24% and 31% in the same tissues. The patient with a full R8X mutation of LIS1 had severe lissencephaly. CONCLUSIONS: Subcortical band heterotopia can occur with mosaic mutations of the LIS1 gene. Mutation analysis of LIS1, using highly sensitive techniques such as denaturing high-pressure liquid chromatography, should be considered for patients with posteriorly predominant subcortical band heterotopia and pachygyria.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2002

Thermoluminescent and dosimetric properties of X ray phosphors.

Rare earth doped oxide, phosphate, etc. are radioluminescent phosphors that have a broad application in X ray imaging, in luminescent screens, image transformers and in fluorescent lamp manufacturing. Some of them have interesting thermoluminescence features as well, which makes the phosphors applicable also in dosimetry. Two of these materials are Sr3(PO4)2 and BaFCl activated with europium. The general radioluminescence (RL) and thermoluminescence (TL) characteristics of these materials was investigated earlier and the preliminary results have already been published elsewhere. The aim of the present work is to investigate the interesting properties of these phosphors mainly from a dosimetric point of view (sensitivity, dose dependence, etc.).

Beta Particles↗
PubMed2000

Aicardi-Goutières syndrome displays genetic heterogeneity with one locus (AGS1) on chromosome 3p21.

We have studied 23 children from 13 families with a clinical diagnosis of Aicardi-Goutières syndrome. Affected individuals had developed an early-onset progressive encephalopathy that was characterized by a normal head circumference at birth, basal ganglia calcification, negative viral studies, and abnormalities of cerebrospinal fluid comprising either raised white cell counts and/or raised levels of interferon-alpha. By means of genomewide linkage analysis, a maximum-heterogeneity LOD score of 5.28 was reached at marker D3S3563, with alpha=.48, where alpha is the proportion of families showing linkage. Our data suggest the existence of locus heterogeneity in Aicardi-Goutières syndrome and highlight potential difficulties in the differentiation of this condition from pseudo-TORCH (toxoplasmosis, rubella, cytomegalovirus, and herpes simplex virus types 1 and 2) syndrome.

Abnormalities, Multiple↗
PubMed1999

Elastic model-based segmentation of 3-D neuroradiological data sets.

This paper presents a new technique for the automatic model-based segmentation of three-dimensional (3-D) objects from volumetric image data. The development closely follows the seminal work of Taylor and Cootes on active shape models, but is based on a hierarchical parametric object description rather than a point distribution model. The segmentation system includes both the building of statistical models and the automatic segmentation of new image data sets via a restricted elastic deformation of shape models. Geometric models are derived from a sample set of image data which have been segmented by experts. The surfaces of these binary objects are converted into parametric surface representations, which are normalized to get an invariant object-centered coordinate system. Surface representations are expanded into series of spherical harmonics which provide parametric descriptions of object shapes. It is shown that invariant object surface parametrization provides a good approximation to automatically determine object homology in terms of sets of corresponding sets of surface points. Gray-level information near object boundaries is represented by 1-D intensity profiles normal to the surface. Considering automatic segmentation of brain structures as our driving application, our choice of coordinates for object alignment was the well-accepted stereotactic coordinate system. Major variation of object shapes around the mean shape, also referred to as shape eigenmodes, are calculated in shape parameter space rather than the feature space of point coordinates. Segmentation makes use of the object shape statistics by restricting possible elastic deformations into the range of the training shapes. The mean shapes are initialized in a new data set by specifying the landmarks of the stereotactic coordinate system. The model elastically deforms, driven by the displacement forces across the object's surface, which are generated by matching local intensity profiles. Elastic deformations are limited by setting bounds for the maximum variations in eigenmode space. The technique has been applied to automatically segment left and right hippocampus, thalamus, putamen, and globus pallidus from volumetric magnetic resonance scans taken from schizophrenia studies. The results have been validated by comparison of automatic segmentation with the results obtained by interactive expert segmentation.

Algorithms↗
PubMed1996

Segmentation of 2-D and 3-D objects from MRI volume data using constrained elastic deformations of flexible Fourier contour and surface models.

This paper describes a new model-based segmentation technique combining desirable properties of physical models (snakes), shape representation by Fourier parametrization, and modelling of natural shape variability. Flexible parametric shape models are represented by a parameter vector describing the mean contour and by a set of eigenmodes of the parameters characterizing the shape variation. Usually the segmentation process is divided into an initial placement of the mean model and an elastic deformation restricted to the model variability. This, however leads to a separation of biological variation due to a global similarity transform from small-scale shape changes originating from elastic deformations of the normalized model contours only. The performance can be considerably improved by building shape models normalized with respect to a small set of stable landmarks (AC-PC in our application) and by explaining the remaining variability among a series of images with the model flexibility. This way the image interpretation is solved by a new coarse-to-fine segmentation procedure based on the set of deformation eigenmodes, making a separate initialization step unnecessary. Although straightforward, the extension to 3-D is severely impeded by difficulties arising during the generation of a proper surface parametrization for arbitrary objects with spherical topology. We apply a newly developed surface parametrization which achieves a uniform mapping between object surface and parameter space. The 3-D procedure is demonstrated by segmenting deep structures of the human brain from MR volume data.

Anatomy, Cross-Sectional↗
PubMed1995

[Occlusive hydrocephalus as a complication of von Recklinghausen's neurofibromatosis--case report].

Phacomatoses are hereditary disease caused by germinative matrix disorder. Apart from known proliferative and tumor processes on peripheral nerves and their roots which make up a familiar picture of this disease to all neurologist, other tissue and organ malformations of octo and mesodermal origin may occur. This is a case report of a girl with neurofibromatosis type I after Riccardi with occlusive hydrocephalus complication. We pointed to a great number of neurofibromatosis complications, their prompt detection and treatment.

Adolescent↗
PubMed1994

[Motor organization in children with encopresis].

The paper reviews the degree of fecal retention in regard to organization of certain functions of central nervous system (motoric, vegetative and psychic), as well as to certain qualities of motoric organization by means of correlation analysis. Gathered results point to connection between poor tonic organization, especially of the axial muscle tonus and neuromuscular binds and the degree of fecal retention; correlations are positive, linear, so that poor motoric organization can be considered basic for the disorder of the pelvic floor muscles function and consequent encopresis.

Adolescent↗
PubMed1992

[Correlation between elevated maternal serum alpha-fetoprotein, certain pregnancy complications and fetal death].

In a prospective epidemiological study of 23,792 singleton pregnancies the authors investigated the relationship between elevated maternal serum alfa-fetoprotein level and the risk of pathological pregnancy outcome. It has been found that elevated level of maternal alfa-fetoprotein (above 2.5 MoM) is associated with a higher risk of pathological pregnancies and an increased risk of subsequent fetal death. Physicians should be aware of the benefits of the maternal alpha-fetoprotein screening not only in the context of prenatal detection of congenital defects, but also in early identification of increased risk of certain obstetric complications.

Female↗
PubMed1992

[Hereditary sensory-motor polyneuropathy. Case report and problems in differential diagnosis].

The study reports a family in which three children were found to have marked sensory-motor polyneuropathy. Clinical investigations revealed a recessive hereditary form of highly progredient mostly motor polyneuropathy with atrophy and weakness of distal muscle groups and electrophysiologic evidence of neurogenic lesion-delayed neural conduction. Apart from the peripheral nerves, clinical examination and additional investigations showed that the degenerative process encompassed central nerve system structures, posterior bundles of the spinal cord, spinal cerebral pathways, cerebellum and cerebrum (cerebral sings, mental retardation, epilepsy, brain atrophy on CT, increased IGG in the liquor are present). Although clinical and electrophysiological analyses suggest type III HSMN, muscle and nerve biopsy, as well as additional diagnostic methods broaden the differential diagnostic range toward other forms of hereditary polyneuropathy, whose differentiation in practice is, in spite of clear diagnostic criteria, rather difficult, due to the presence of its transitive forms.

Adolescent↗
PubMed1992

[Drug therapy of nocturnal enuresis].

Bed wetting is a disorder the origin of which different authors find in different etiopathogenetic mechanisms. Depending on the etiologic concept different therapeutic methods have been used. Treating bed wetting, authors claiming that the basic cause is a disorder in the integration of central vegetative functions and sleep, most frequently administer anticholinergic agents, making use of their marginal central anticholinergic effect and their impact on sleep phases. For children who wet in bed, having an urodynamic disorder and the disordered function of the pelvic floor musculature, effective drugs would be those with peripheral anticholinergic effects as well as pelvic floor musculature reeducation exercises. In conformity with the current understanding of the bed wetting etiology due to disordered Adiuretin excretion circadian rhythm, the applied drug is synthetic Adiuretin. It has been pointed out that bed wetting, being a heterogeneous group of disorders, should be etiologically classified by additional diagnostic methods, and that the treatment should include aimed etiological therapeutical methods.

Child↗
PubMed1991

[Cerebellitis? Case report of acute cerebellar ataxia in childhood].

The authors present a severe clinical manifestation of acute cerebellitis with a favorable outcome, most likely of viral etiology, without fever. An emphasis is placed on the value of complex investigations, clinical as well as laboratory ones, and the exclusion of other diseases which come into consideration in differential diagnostics.

Acute Disease↗
PubMed1990

A plea for the diagnosis of hypochondriacal personality disorder.

Hypochondriacal personality disorder is identified as a separate condition by cluster analysis of data from a structured interview for assessing personality disorders, the Personality Assessment Schedule. Close examination of the patients identified as having hypochondriacal personality disorder suggests that they have common characteristics, including excessive preoccupation with the maintenance of health, distorted perception of minor symptoms so that they are elevated to the status of major disease, and frequent medical consultations and disciplines fringing on medicine. In a study of 1000 psychiatric patients 2.5% were found to have the disorder, most frequently among the affective psychoses.

Adjustment Disorders↗
PubMed1989

[Changes in the clinical picture of chorea minor].

The paper dealt with the change in clinical picture of chorea minor. It used to be a very frequent disease but now it is all the rarer appearance and it always occurs as a complication of rheumatic disease. Except for its rarer frequency, once it has occurred it is more often complicated by cardiac incidents, the course of disease is longer and more resistant to therapy and is accompanied by psychic changes without frequent relapses observed in its previous appearances. Contemporary immunologic knowledge of this field has detected the complex neuroimmunologic changes taking place in CNS. According to the authors' opinion, modification of the clinical picture is the sequel of the broad application of antibiotics in general but the prevalence of chorea in girls keeps remaining unclear. However, there is no specific attritude toward neuroimmunologic mechanism so far, because previous knowledge of this problem is lacking.

Adolescent↗