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Biomedical subjects

G Barabas

Publications and source records attributed to G Barabas.

At least 19 recordsLinked to original sources
PubMed2001

Ocular motor dysfunction in Lesch-Nyhan disease.

Eye movements were assessed in 22 patients with varying degrees of hypoxanthine-guanine phosphoribosyltransferase deficiency. Ocular motility was clinically normal in seven patients with moderate enzyme deficiency but grossly abnormal in 15 patients with severe enzyme deficiency. In patients with severe deficiency, fixation was interrupted by frequent unwanted saccades toward minor visual distractions. Voluntary saccades were associated with an initial head movement and/or eyeblink in all of these patients. When head motion was prevented, voluntary saccades were often delayed and sometimes absent. In contrast, saccade speed, reflexive saccades, and other reflexive eye movements appeared clinically normal. Four patients with severe enzyme deficiency also experienced mild blepharospasm, and two had ocular tics. These disturbances of ocular motility are consistent with dysfunction of the basal ganglia or its connections with ocular motor centers in the prefrontal cortex or midbrain.

Adolescent↗
PubMed1999

Cognitive functioning in Lesch-Nyhan syndrome: a 4-year follow-up study.

Lesch-Nyhan syndrome (LNS) is a rare disorder of metabolism caused by a defective gene on the X chromosome. It is typically characterized by choreoathetosis, hypertonia, hyperreflexia, and self-mutilation. The present study is a 4-year follow-up investigation of the cognitive status of six subjects with a mean age of 17 years 10 months (range 14 years 9 months to 23 years). The Stanford-Binet Intelligence Scale: IV was used. Each of the four domains assessed by this battery (verbal reasoning, abstract/visual reasoning, quantitative, and short-term memory) was compared with previous findings of the same subjects at their initial test and 2-year follow up; the aim being to gain further insight into the clinical course of LNS over time. The results suggest that while the subjects generally continued to acquire new information and skills over time, their standardized scores declined, indicating that a plateau was reached in their skill levels relative to their peers, as also seen in other developmental disabilities. Deficits were noted in working memory, particularly on tasks that involve considering multiple features simultaneously.

Adolescent↗
PubMed1995

Cognitive functioning in Lesch-Nyhan syndrome.

The present study represents the first effort to assess systematically the cognitive functioning of a population of individuals with Lesch-Nyhan syndrome using standardized psychometric instruments. Seven residents from a special hospital setting participated. They ranged in age from 10 years 1 month to 22 years 3 months (mean 13 years 7 months). Using the Stanford-Binet Intelligence Scale: IV, scores in each of the four domains assessed by this battery (Verbal Reasoning, Abstract/Visual Reasoning, Quantitative and Short-Term Memory), as well as the general composite score, ranged from moderately mentally retarded to low average. Areas of weakness included attention, the manipulation of complex visual images, the comprehension of complex or lengthy speech, mathematical ability, and multi-step reasoning.

Adolescent↗
PubMed1993

Age-dependent changes in transmembrane signalling: identification of G proteins in human lymphocytes and polymorphonuclear leukocytes.

In human neutrophils (PMNLs) we found that in the elderly IP3 formation was significantly decreased compared to that of young subjects. For FMLP receptor binding affinity and number no measurable differences occurred upon ageing, studying both the low or the high affinity receptors. The amount of ADP-ribosylated G proteins, catalysed by pertussis toxin (PT) or cholera toxin (CT), was significantly increased in PMNLs of the elderly. In lymphocytes, the PT-catalysed ADP ribosylation of G proteins was also increased with ageing, while the CT-catalysed ribosylation was decreased. The autoradiogram of [32P]ADP-ribosylated proteins by CT in lymphocytes of young individuals showed a major polypeptide of 40,000 M(r). In contrast, in lymphocytes of the elderly, the major polypeptide was 45,000 M(r). In PMNLs, CT labelled quite strongly the 45,000 M(r) band, mainly in the elderly. When PT was used, no age-related pattern changes could be demonstrated, while differences could be observed between the two types of cells. The use of antiserum P680 (G alpha common) showed no age-related pattern changes, while the intensity of the labelled proteins varies with age and cell type. The antiserum U46 (Go alpha) could identify in lymphocytes of young subjects two polypeptides 68,000 and 41,000 M(r). The prominent polypeptide in lymphocytes of the elderly was the 70,000 M(r) and no other polypeptides could be recognized. In PMNLs of young subjects the U46 and serum identified a range of species. In PMNLs of the elderly all these bands were weakly labelled. The present data indicate changes in the pattern and the quantity of G proteins in lymphocytes and PMNLs of elderly subjects.

Adenosine Diphosphate Ribose↗
PubMed1992

The possible role of ADP-ribosylation in sporulation and streptomycin production by Streptomyces griseus.

Mutants resistant to 3-aminobenzamide, a known inhibitor of ADP-ribosyltransferase, were obtained from Streptomyces griseus IFO 13189, a streptomycin-producing strain. One (strain no. 4), which had significantly reduced ADP-ribosyltransferase activity, was analysed in detail. Mutant 4 displayed a conditional phenotype with respect to cultivation temperature. At 30 degrees C, it exhibited severely reduced ability to produce aerial mycelium (on solid medium) and submerged spores and streptomycin (in liquid culture), but this ability was fully restored at 25 degrees C. The mutant produced A-factor normally, regardless of cultivation temperature, and exhibited normal ability to accumulate ppGpp intracellularly. SDS-PAGE analyses of cellular proteins labelled by [32P]NAD revealed that an ADP-ribosylated protein with a molecular size of 44 kDa, which appeared in sporulating cultures of the parent strain, was missing from the mutant grown at the non-permissive temperature (30 degrees C). Genetic analysis showed that the aba mutation conferring resistance to 3-aminobenzamide was tightly linked to the altered phenotype. Failure to ADP-ribosylate certain cellular protein(s), presumably due to the aba mutation, may be responsible for impaired differentiation in this mutant.

Adenosine Diphosphate↗
PubMed1992

Care-load for children and young adults with severe cerebral palsy.

Care-load was analysed for 44 children and young adults (mean age 18.9 years) with severe spastic quadriplegia. All were enrolled in a residential school/hospital and used wheelchairs. The majority were in the moderate to borderline range of mental retardation. They were monitored for 24 hours a day over a seven-day period, and were timed in 10 major activities, including basic care (bathing, toileting, dressing, grooming, feeding), as well as sleep, leisure, education/vocation, counseling/psychosocial therapy, medical/nursing care, transportation, and at home. The findings replicated those of an earlier Swedish study, which suggests that the basic care needs of individuals with severe cerebral palsy may be predictable, regardless of the type of care being provided.

Activities of Daily Living↗
PubMed1988

Tourettism.

Explore the source record for details and available documents.

Autistic Disorder↗
PubMed1987

Central nervous system neoplasm in a young man with Martin-Bell syndrome--fra(X)-XLMR.

A 17-year-old retarded male developed unilateral leg weakness with foot drop, pain, and incontinence. Workup disclosed a cauda equina tumor which, on surgical exploration, was demonstrated to merge with the conus medullaris. Pathological examination of the subtotally resected tumor led to a diagnosis of malignant ganglioglioma. Further evaluation of the patient documented marginal macro-orchidism, and chromosome studies showed fragile X. Since some neoplasms are known to be associated with chromosomal deletions and other abnormalities, we suggest that the occurrence of this tumor in this patient indicates a more than coincidental relationship between the two diagnoses.

Adolescent↗
PubMed1986

Neurologic correlates of osteogenesis imperfecta.

The neurologic status of ten patients with osteogenesis imperfecta (OI) was evaluated. Four patients with mild OI (type I) had normal neurologic findings and normal computed tomographic scans. Three of these four patients had macrocephaly. All six patients with severe OI (type III) had cortical atrophy on computed tomographic scan and three were also macrocephalic.

Adolescent↗
PubMed1986

Coincident Down's and Tourette syndromes: three case reports.

Three patients with Down's syndrome and coincident Tourette syndrome are presented. Two patients had trisomy for G-group chromosome and one patient had mosaic trisomy. All had characteristic features of Gilles de la Tourette syndrome with multiple motor and vocal tics. While Tourette syndrome has been reported in other chromosomopathies, this report appears to be the first to note an association with Down's syndrome. The authors hypothesize that neurotransmitter abnormalities existing in Down's syndrome may predispose such individuals to basal ganglia dysfunction and the subsequent development of tics. In particular, abnormalities in serotonin metabolism may be involved.

Adolescent↗
PubMed1986

Social quotients of children with phenylketonuria before and after discontinuation of dietary therapy.

The records of 16 early-treated children with phenylketonuria (PKU) whose low-phenylalanine diets had been discontinued at an average age of 5.5 years were reviewed for evidence of deterioration in functioning. Measures of their medical and social status, namely, serum phenylalanine levels and Vineland Social Quotients, before and after diet discontinuation were investigated via repeated measures analyses of variance. Social quotients decreased significantly following discontinuation and were inversely correlated with serum phenylalanine levels.

Child↗
PubMed1985

Homogeneous clinical subgroups in children with Tourette syndrome.

The existence of two clinically homogeneous subgroups in Tourette syndrome, depending upon the presence or absence of migraine or a family history of migraine, is suggested. Patients with Tourette syndrome who have migraine (n = 18) were found to have a significantly higher prevalence of disorders of arousal--particularly sleepwalking and night terrors--as well as a higher prevalence of motion sickness than patients without migraine (n = 27). They were also significantly more likely to exhibit a co-occurrence of associated features (two or more) than the patients without migraine. Patients with Tourette syndrome who have not had migraine headaches but in whom there is a family history for migraine (n = 20) were shown to have an intermediate prevalence of associated symptoms. It is suggested that the differential association for these symptoms in patients with Tourette syndrome may reflect an underlying abnormality in function of two different neurotransmitter systems.

Arousal↗