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Biomedical subjects

R Orrell

Publications and source records attributed to R Orrell.

6 recordsLinked to original sources
PubMed2002

Familial adult onset of Krabbe's disease resembling hereditary spastic paraplegia with normal neuroimaging.

Krabbe's disease (globoid cell leucodystrophy) is a disorder involving the white matter of the peripheral and central nervous systems. Mutations in the gene for the lysosomal enzyme galactocerebrosidase (GALC) result in low enzymatic activity and decreased ability to degrade galactolipids found in myelin. The disease is classically of infantile onset, but adult onset cases have been reported. Magnetic resonance imaging (MRI) of the brain shows characteristic abnormalities. A unique family with Krabbe's disease is described, with proven GALC deficiency but normal MRI. A neurological phenotype is present in heterozygotes and the family shows the extent of homozygotic phenotypic diversity that can be seen in this disorder.

Adult↗
PubMed1999

Saccades and smooth pursuit in myotonic dystrophy.

Reflexive saccades, remembered saccades, antisaccades, fixation and smooth pursuit were recorded in seven subjects with myotonic dystrophy (MD) and seven age-matched controls using the magnetic scleral search coil technique. Neuropsychological performance was assessed using the Wisconsin Card Sort Test and measures of verbal fluency. Subjects with MD showed significantly elevated error rates in the antisaccade and remembered saccade paradigms, consistent with prefrontal dysfunction, and these two measures of distractibility were significantly correlated with each other. Saccadic latencies, square wave jerk frequency, and smooth pursuit peak velocity gain showed no significant difference between the two groups, although the peak velocity of all classes of saccades was significantly reduced in patients with MD. These results extend the findings of previous studies of oculomotor function in MD, and provide novel evidence for a central contribution to abnormalities of eye movements in this condition.

Adolescent↗
PubMed1994

Relation of boron to the composition and mechanical properties of bone.

A review of the experimental studies relating boron to biological effects on appendicular and axial bones in animal models suggests that numerous influences, known and unknown, affect the responsiveness of bone to dietary boron. Degrees of skeletal response to boron are modified by other nutritional variables that include calcium, magnesium, vitamin D, and fluoride. Evidence suggests that appendicular and axial bones may differ in their responses. Tests of the mechanical properties of bones may provide useful criteria for assessing the impacts of boron status on bone. These tests might resolve questions about optimal intakes of boron because mechanical properties sometimes respond to boron when composition of bones does not. Difficulty in interpreting some of the existing research arises because of the incipient state of knowledge regarding boron nutriture, to analytical problems associated with determining accurately the small quantities of boron in feed and tissues, and to technological difficulties in controlling extraneous exposure of experimental animals to boron. Yet there is considerable evidence that both compositional and functional properties of bone are affected by boron status.

Animals↗