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Biomedical subjects

T J Leonard

Publications and source records attributed to T J Leonard.

31 records · Page 2Linked to original sources
PubMed1984

Ophthalmoplegia in carotid cavernous sinus fistula.

The aetiology of ophthalmoplegia in 15 patients with carotid-cavernous sinus fistula is discussed, and the clinical findings are correlated with angiographic and orbital CT appearances. After closure of the fistula the majority of patients with generalised ophthalmoplegia recovered full ocular movements rapidly, while patients with an isolated abduction weakness required much longer to return to normal. Orbital CT studies showed enlarged extraocular muscles in the patients with generalised ophthalmoplegia but muscles of normal size in those with abduction failure alone. After closure of the fistula repeat CT studies of patients with enlarged extraocular muscles showed a diminution in muscle size. We suggest that generalised ophthalmoplegia in carotid cavernous sinus fistula is due to hypoxic, congested extraocular muscles. Isolated abduction weakness is due to a sixth nerve palsy, which probably occurs either in the cavernous sinus or more posteriorly near the inferior petrosal sinus. A combination of these 2 mechanisms may be found in some patients.

Adult↗
PubMed1984

Deliberate alteration of the visual evoked potential.

Seven out of 12 normal subjects could deliberately produce abnormal pattern-reversal visual evoked potentials (VEPs) which simulated disorders of the anterior visual pathways without detection. In six the mechanism was near-point accommodation and in one eccentric fixation. If voluntary suppression of the VEPs is suspected various modifications to the recording technique may be of value. These include the use of a large check size and stimulus field and binocular stimulation.

Adult↗
PubMed1984

Intracerebral haemorrhage complicating dural arteriovenous fistula: a report of two cases.

Two patients presented with unilateral peri-orbital pain, proptosis, chemosis and external ophthalmoplegia. They were shown to have dural arteriovenous fistulae related to the cavernous sinus. Intracerebral haemorrhage occurred in both patients within 18 months of presentation; this gave rise to focal seizures and signs of unilateral hemisphere dysfunction. The haematomas were in the region drained by the superficial middle cerebral vein ipsilateral to the shunt and are presumed to have been the result of locally raised venous pressure.

Aged↗
PubMed1983

Ocular hypertension and posture.

Thirty-seven patients with ocular hypertension (OH) and 29 age matched controls were studied. Intraocular pressure (IOP) measurements were made in the sitting position and, immediately after changing posture, in the lying position. Sixty-three (85%) of the OH eyes and all the control eyes showed either stable IOP readings on changing posture of small elevations up to 3 mmHg. Eleven (15%) of the OH eyes showed larger elevations of IOP, between 5 and 9 mmHg when the patients changed to the lying position. We suggest that an IOP measurement in the lying position should be included in the routine evaluation of the patient with ocular hypertension.

Female↗
PubMed1983

Life on implants.

Seven Ridley Mark I anterior chamber lenses were removed from patients at St Thomas's Hospital. The lenses had been in place for an average of 15 years. The indication for removal was corneal endothelial decompensation with painful bullous keratopathy. Examination of the lenses under the scanning electron microscope showed remarkably similar morphology in each case. A well organised fibrin membrane covered the implants to which iris pigment epithelial cells were adherent. Red blood cells, scattered fibroblasts and pigment granules were also found. Giant cells were not identified while macrophages and lymphocytes were rare. These findings suggest that corneal endothelial decompensation was not due to chronic inflammation but was probably caused by movement of the implants within the eyes.

Adult↗
PubMed1975

An inherited "neoplasm" in fungus.

An abnormal growth form in the fungus Schizophyllum commune is described that interferes with the development of reproductive structures. The abnormality, which takes the form of relatively large, compact, hemispherical bodies, depends on a dominant Mendelian gene, mound, for its expression. When mound is expressed in a mycelium that has the potential to form fruiting bodies, the fruiting response is affected and the effect is variable within a replicate series: fruiting bodies may be normal or abnormal, abort at various stages, or not develop at all. Occasionally, fruit bodies are overgrown and are completely enveloped by the hemispherical bodies. When hyphae from hemispherical bodies are subcultured, a seemingly normal mycelium forms that eventually differentiates hemispherical structures, but the ability to form fruiting bodies in not expressed. Continuous mycelial subculture has shown this loss of fruiting expression to be a permanent transformation, which is demonstrated to be a characteristic of hemispherical bodies.

Agaricales↗
PubMed1973

Study of phenoloxidase activity during the reproductive cycle in Schizophyllum commune.

A study of the temporal relationship between the appearance of phenoloxidase activity and the formation of fruiting bodies in Schizophyllum commune was undertaken. The results indicate that phenoloxidase activity increases in colonies subsequent to the formation of aggregate masses of hyphae, continues to increase until mature, sporulating fruiting structures are produced, and then declines significantly.

Basidiomycota↗
PubMed1971

Phenoloxidase activity and fruiting body formation Schizophyllum commune.

Studies of induced haploid fruiting in the Basidiomycete Schizophyllum commune suggested that polyphenoloxidase enzymes may participate in the formation of fruiting bodies. Reported inhibitors of phenoloxidases were found to affect both the activity of these enzymes and the fruiting response. Fertile mycelia were found to give a positive Bavendamm reaction in situ, and cell-free extracts from fertile mycelia exhibited polyphenoloxidase activity when studied spectrophotometrically. Sterile mycelia, on the other hand, were devoid of these activities. Various kinds of mutant homo- and dikaryotic mycelia were studied, and the results suggested a correlation between phenoloxidase activity and fruiting body formation in S. commune.

Aminobenzoates↗