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Biomedical subjects

D Taylor

Publications and source records attributed to D Taylor.

At least 505 records · Page 28Linked to original sources

Disorders of head and eye movements in children.

Disturbances of the normal relationship of head and eye movements occur in several pathological conditions, including disorders of rapid eye movements and various forms of congenital nystagmus. In disorders of rapid eye movements the abnormal head movements may be a learned response using various techniques to improve eye velocity and amplitude. In congenital nystagmus with head shaking, the head movements may be compensatory, of common genesis, or suppressive. The vestibulo-ocular reflex may be manipulated in certain circumstances to achieve eye stability or to increase eye movement velocity. In certain head tremors the eye movements observed may be normal vestibulo-ocular compensatory movements.

Apraxias↗

MAO, DBH and COMT: the effect of anxiety.

Anxiety, a common accompaniment of depression, can be a source of confusion in affective disorder research. The present study examined the effect of anxiety on platelet monoamine oxidase, RBC catechol-0-methyltransferase, and serum dopamine-beta-hydroxylase-enzymes frequently implicated in affective disorders. Levels of anxiety, plasma catecholamines and the enzymes mentioned above were quantified in groups of anxious subjects and mentally and physically healthy controls. Anxious subjects were found to have significantly higher levels of blood plasma catecholamines and platelet monoamine oxidase. significant positive correlations were demonstrated between plasma catecholamines and platelet monoamine oxidase, while significant inverse correlations were found between trait anxiety and COMT, norepinephrine and DBH, and COMT and DBH

Adult↗

Opioid peptides excite pyramidal neurons and evoke epileptiform activity in hippocampal transplants in oculo.

The effect of opiate peptide administration on the electrical activity of intraocular hippocampal transplants was studied. Similar to observations in situ, the administration of beta-endorphin or methionine enkephalin produces a concentration-dependent increase in the firing rate of identified pyramidal neurons within hippocampal formation transplants. In addition, these peptides elicit a profound increase in 'EEG' amplitude, which ultimately develops into epileptiform activity. The ability of naloxone to either reverse or prevent the peptide-induced changes in both single unit and EEG activity supports the hypothesis that the excitatory response of the hippocampus to opioid peptides is mediated via an opiate receptor. The results of this study also suggest that the excitatory response to the opiate peptides in hippocampus is the result of alterations in intrinsic neuronal circuitry and is not dependent upon extra-hippocampal afferents.

Animals↗

Britain's NHS: problems we all may face.

Is Britain's nationalized health care system experiencing and coping with pressures that other nation's health care systems will have to face in the future?

Delivery of Health Care↗

Isolated catecholaminergic projections from substantia nigra and locus coeruleus to caudate, hippocampus and cerebral cortex formed by intraocular sequential double brain grafts.

Sequential intraocular grafting of defined areas from fetal rat brain to adult host rats was used to explore the possibility that such double grafts would become interconnected. Norepinephrine- containing neurons of the locus coeruleus were grafted together with either parietal cerebral cortex, hippocampus, or the caudate nucleus. Dopamine-containing neurons of the substantia nigra were transplanted together with either parietal cerebral cortex or the caudate nucleus. The brainstem grafts showed good survival and development in oculo, using both histochemical and electrophysiological criteria. Locus coeruleus neurons were found to innervate cerebral cortex, hippocampus, and the caudate nucleus. Substantia nigra neurons invaded cerebral cortex abundantly, with a terminal distribution typical of cortical DA terminals in situ. The innervation of the caudate nucleus from substantia nigra transplants was variable, but areas of dense confluent terminals were observed. We conclude that sequential brain grafting in oculo permits generation of isolated yet defined catecholaminergic projections, which are suitable for electrophysiological, pharmacological, and histochemical studies.

Animals↗

Amblyopia in bilateral infantile and juvenile cataract. Relationship to timing of treatment.

Contact lenses were fitted for 51 aphakic infants. From this group data were obtained that support the hypothesis that much of the visual defect in cases of congenital cataract is due to functional amblyopia, and that it is therefore largely preventable and even treatable. The implications of the results for the management of these patients and for human amblyopia are that early treatment and optical correction are essential, since the effects of deprivation start at about 4 months of age and continue to a cumulative but decreasing degree throughout the first decade of life.

Amblyopia↗

Critical period for deprivation amblyopia in children.

The critical period in which human visual acuity may be lost after visual deprivation can be deduced by studying children with amblyopia which follows uncomplicated unilateral cataract and the subsequent aphakic blur. The visual acuity at the first contact lens fitting increases linearly on a log scale as a function of the age at onset between 3 and 10 years. Correction before 4 months of age produces less visual loss but we cannot specify the function within this period. If the eye is deprived between 6 and 30 months of age finger counting is the best visual acuity achieved. Deprivation commencing between the ages of 3 and 10 years differs only in that vision reduces at a slower rate and is more likely to respond to total full-time occlusion. Similarly, some unilateral high myopes responded well and three unilateral aphakes who are blind in the other eye slowly achieved good vision. Part-time occlusion and Cam treatment were seldom effective. Children appear to have a critical period which continues for longer than expected from animal models.

Age Factors↗