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Biomedical subjects

K North

Publications and source records attributed to K North.

At least 37 records · Page 2Linked to original sources
PubMed1996

Oxidative phosphorylation defect associated with primary adrenal insufficiency.

An 18-month-old girl with an oxidative phosphorylation defect had neonatal onset of chronic lactic acidosis, lipid storage myopathy, bilateral cataracts, and primary adrenal insufficiency. Chronic lactic acidosis responded to treatment with dichloroacetate. Sequential muscle biopsies demonstrated resolution of the lipid storage myopathy associated with the return to normal muscle free carnitine levels. This case demonstrates a new clinical phenotype associated with a defect in oxidative phosphorylation and the need to consider mitochondrial disorders in the differential diagnosis of primary adrenal insufficiency in childhood.

Acidosis, Lactic↗
PubMed1995

17q inversion involving the neurofibromatosis type one locus in a family with neurofibromatosis type one.

We report a family with a paracentric inversion of the long arm of chromosome 17 [inv(17)(q11.2q25.1)] and neurofibromatosis type one (NF1). The family was ascertained because of NF1 and multiple miscarriages. Fluorescence in situ hybridization using cosmid probes from opposite ends of the NF1 gene confirmed that the inversion disrupts the gene. Using field inversion gel electrophoresis we have found that the inversion separates cDNA probes FB5D and AE25, which are normally adjacent to one another in the NF1 gene. This is the third published report of a gross chromosomal rearrangement responsible for NF1. The features in this family are typical for NF1, and are not unusually severe.

Adolescent↗
PubMed1995

Neuropsychological function and MRI abnormalities in neurofibromatosis type 1.

This study investigated the relationship between MRI abnormalities and cognitive function in neurofibromatosis type 1.40 children aged eight to 16 years underwent comprehensive neuropsychological, medical and neuroradiological assessments. MRI scans revealed a characteristic pattern of T2-weighted signals ('UBOs') located primarily in the basal ganglia, brainstem and cerebellum in 25 of the children. Reductions in global IQ, attention, and visuopatial and executive functions were shown to occur in association with the presence of UBOs. These findings establish a link between changes in neuropsychological functions and MRI abnormalities in NF-1, and further support neuropathological findings which suggest that UBOs may be a manifestation of delayed or disordered myelination.

Adolescent↗
PubMed1995

Cognitive function and academic performance in children with neurofibromatosis type 1.

The authors evaluated 51 consecutive children with NF1 (aged eight to 16 years) to determine the frequency of intelectual impairment and learning disability due to NF1 alone, the profile of learning disabilities and the effect of clinical variables. 40 children completed the full assessment protocol. There was no support for a profile of predominantly visuoperceptual deficits in the NF1 population. There was no discrepancy between verbal and performance IQ, and the deficits in function were wide ranging. Clinical variables such as age, sex, socio-economic status, disease severity, macrocephaly and family history of NF1 were not associated with cognitive deficits. These results emphasise the need for developmental evaluation to be included in the routine assessment of children with NF1.

Adolescent↗
PubMed1994

Optic gliomas in neurofibromatosis type 1: role of visual evoked potentials.

Optic gliomas occur in 15% of patients with neurofibromatosis type 1 (NF 1) and are a significant cause of morbidity. Of these tumors, 20-30% become symptomatic, usually before age 10 years. Previous studies have suggested that visual evoked potentials (VEPs) are a sensitive method for the detection of asymptomatic optic gliomas. Because routine neuroimaging of children with NF 1 is currently not recommended, the role of pattern-shift VEPs (PS VEPs) as a screening test for optic gliomas was evaluated. PS VEPs were performed on 10 children with NF 1 and optic gliomas and 20 children with NF 1 and normal visual pathways (as defined on MRI). PS VEPs had 90% sensitivity for detecting optic gliomas, with an increase in sensitivity to 100% when hemifield stimulation was used. The specificity of the test was 60%. Four of 20 children without optic gliomas had thickened optic nerves on computed tomography which represented dural ectasia with normal visual pathways on MRI; PS VEPs were normal in these patients. The efficacy of PS VEPs as a routine screen for optic gliomas is limited by the age at which children will cooperate with the test procedure and the high incidence of false-positive results; however, VEPs do provide a useful adjunct to routine clinical ophthalmologic assessment in the detection of optic gliomas in children with NF 1. Abnormal test results provide a stronger indication for neuroimaging. The early detection of optic gliomas allows for close monitoring of tumor progression and earlier intervention prior to significant visual loss.

Adolescent↗
PubMed1994

Specific learning disability in children with neurofibromatosis type 1: significance of MRI abnormalities.

To determine whether previously reported areas of increased T2 signal intensity on MRI examination in children with neurofibromatosis type 1 (NF 1) are associated with deficits in development and learning common in this population, we evaluated 51 children with NF 1 (aged 8 to 16 years). Forty children completed the full assessment protocol (MRI, medical, psychometric, speech therapy, and occupational therapy assessments). The mean Full Scale IQ scores for the entire study population showed a left shift compared with the normal population, and the distribution of IQ scores was bimodal, suggesting that there are two populations of patients with NF 1--those with and those without a variable degree of cognitive impairment. There was no association between lower IQ scores and any clinical variable. Areas of increased T2 signal intensity unidentified bright objects (UBO+) were present in 62.5% of the study population, and their presence was not related to clinical severity, sex, age, socioeconomic status, macrocephaly, or family history of NF 1. However, compared with children without areas of increased T2 signal intensity (UBO-), the UBO+ group had significantly lower mean values for IQ and language scores and significantly impaired visuomotor integration and coordination. Children with areas of increased T2 signal intensity were at a much higher risk for impaired academic achievement. Children without increased T2 signal on MRI (UBO-) did not significantly differ from the general population in any measure of ability or performance. Areas of increased T2 signal on MRI represent dysplastic glial proliferation and aberrant myelination in the developing brain and are associated with deficits in higher cognitive function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Hemiplegia due to posterior cerebral artery occlusion.

BACKGROUND: Hemiplegia is a rare manifestation of posterior cerebral artery occlusion. The acute clinical picture may be difficult to differentiate from occlusion of the middle cerebral artery. A mechanism for the hemiplegia has not been conclusively determined. CASE DESCRIPTION: We describe a patient with hemiplegia secondary to posterior cerebral artery occlusion by an embolized fragment of a prosthetic valve. Computed tomographic scan showed the foreign body just distal to the origin of the posterior cerebral artery with infarction of its vascular territory. These findings were later confirmed at autopsy. There was no radiological or autopsy evidence of involvement of the other cerebral arteries or their territories. CONCLUSIONS: The patient provides further evidence that occlusion of the posterior cerebral artery just distal to its junction with the posterior communicating artery may produce contralateral hemiplegia without oculomotor nerve nucleus involvement.

Adolescent↗
PubMed1993

Brain-stem encephalitis caused by Epstein-Barr virus.

A case of brain-stem encephalitis with strong serologic evidence of acute Epstein-Barr virus infection is described. Recovery was rapid without treatment, but mild neurologic sequelae were seen at 6-month follow-up. Epstein-Barr virus infection in childhood may be asymptomatic and heterophil antibody negative. Encephalitis is an unusual but well-recognized complication of Epstein-Barr virus infection, but localized brain-stem involvement, to our knowledge, has not been previously described.

Antibodies, Viral↗
PubMed1993

Neurofibromatosis type 1: review of the first 200 patients in an Australian clinic.

Neurofibromatosis type 1 is a common multisystem disorder, best managed in a multidisciplinary clinic. In 1991, the first Australian neurofibromatosis clinic was established at the Children's Hospital, Camperdown, and the clinical characteristics of the first 150 families are reviewed. Two hundred individuals were assessed; there was an equal sex distribution, and 55% of cases were sporadic. Advanced paternal age appeared to predispose to new mutations in the neurofibromatosis gene. Café-au-lait spots and axillary freckling were important to the diagnosis of neurofibromatosis type 1 during childhood, and neurofibromas and Lisch nodules, although often not appearing until after puberty, were present in almost all patients over 30 years of age. Short stature (27%), macrocephaly (43%), scoliosis (20.5%), and learning disabilities (45%) were common associated features. The prevalence of disease complications was similar to the major US and European studies.

Adolescent↗
PubMed1987

Neurotomes and birth defects: a neuroanatomic method of interpretation of multiple congenital malformations.

It has been suggested that complexes of multiple congenital malformations, involving limbs and viscera, may be caused by embryonic neural crest injury. Structures supplied by the sensory and autonomic nerves derived from the injured zone of crest would suffer defective development through presumed impairment of neurotrophic influence. Our study aimed to examine this concept by a retrospective analysis of autopsy findings in 27 babies who died of multiple congenital malformations associated with longitudinal limb defects. Sclerotome maps of the segmental sensory innervation of the skeleton were used to analyse the limb defects in terms of their nerve supply. From a review of the literature, the approximate segmental contribution of neural crest to the autonomic innervation of internal organs was ascertained, and thus "viscerotome" diagrams were constructed. Application of sclerotomes and viscerotomes to the data derived from the autopsy reports showed a neuroanatomic correlation in 89% of cases. Interpretation of multiple malformation syndromes is proposed on the basis of neurotomes, or embryonic developmental fields with common regional innervation.

Abnormalities, Multiple↗
PubMed1984

Thalidomide deformities and their nerve supply.

The aim of this study was to test the hypothesis that thalidomide acts upon the embryonic peripheral nervous system rather than upon mesenchyme. Pregnant rabbits were given oral thalidomide (150 mg/kg/day) on Days 7-11 of gestation. Fetuses were removed at laparotomy, under anaesthesia, on Day 29 of gestation. Seven fetuses with partial or total absence of the tibia, five treated fetuses without deformities, and four untreated controls were photographed, radiographed, killed and fixed for histological examination. Sciatic nerves were dissected and transverse sections were taken from an identical site. Total fascicular area, myelinated fibre number, fibre density and diameter distribution were obtained. There was a significant reduction in total fascicular area, and in the number of large diameter fibres in all treated animals. There was a significant depletion of total fibre numbers in deformed fetuses compared with controls. These findings are similar to the quantitative changes described in human adult subjects with thalidomide polyneuropathy, and are consistent with primary axonal degeneration in both instances. It is concluded that thalidomide acts upon embryonic nerves rather than on mesenchyme, and that dysmelic deformities of the limbs are secondary to toxic embryonic neuropathy. It is suggested that skeletal defects result when irreversible damage to the nerves reduces the transverse fascicular area below a critical minimum threshold.

Abnormalities, Drug-Induced↗
PubMed1980

[Job analysis applied to the disabled (author's transl)].

Job analysis data are helpful in solving a wide range of rehabilitation and ergonomic problems. The ergonomic job analysis procedure for the disabled is based on a universal procedure, called AET (Arbeitswissenschaftliches Erhebungsverfahren zur Tätigkeitsanalyse). To this basic procedure a supplement for the analysis of jobs for the disabled has been developed. The idea of supplementing a basic job analysis procedure for special purposes enables us not only to compare (cluster analysis) basic data of a wide range of jobs but also to analyse groups of jobs in more detail. This paper describes structure and contents of the supplement for the disabled. Examples for application are given.

Disability Evaluation↗