Biomedical subjects

A Gosbell

Publications and source records attributed to A Gosbell.

4 recordsLinked to original sources

PubMed1996

Long chain polyunsaturated fatty acids and visual function in preterm infants.

Electroretinograms (ERG) were recorded at 40 weeks post-conceptual age (PCA) in 18 infants born prematurely (25-32 weeks gestation). Fatty acid composition of plasma and red cell phospholipids was measured within 4 days of birth and at time of ERG testing, and detailed record was kept of dietary intake. Correlations were seen between percentage intake of breast milk and docosahexaenoic acid (DHA) in both plasma (r = 0.818, P < 0.0001) and red cells (r = 0.534, P = 0.035) and significant differences in fatty acid profiles were seen between infants receiving > 50% and < 50% breast milk. No difference was seen in retinal sensitivity between infants receiving > 50% or < 50% breast milk. A positive correlation was seen between scotopic (rod) b-wave implicit time on ERG and DHA in both plasma (r = 0.733, P = 0.001) and red cells (r = 0.502, P = 0.04). A positive correlation was seen between arachidonic acid and rod ERG amplitude (r = 0.565, P = 0.022) which may reflect the higher AA/DHA ratio in the developing retina. These data did not support our hypothesis that increased dietary DHA results in enhanced retinal maturation. Visual acuity measured at 40 weeks PCA and again 3 months later was similar between groups. While subtle relationships were demonstrated between long chain polyunsaturated fatty acids and visual function, all infants were felt to be within age-appropriate normal range at expected date of delivery and at 3 months corrected age.

Breast Feeding↗

PubMed1996

The effects of insulin on the electroretinogram of bovine retina in vitro.

PURPOSE: This study investigates the role of insulin in retinal function by examining the effects of insulin on the a- and b-waves of the electroretinogram (ERG) recorded from an in vitro bovine retina eye-cup preparation. METHODS: Bovine eyes were enucleated immediately after exsanguination, hemisected to form an eye cup, and transported to the laboratory in oxygenated medium. Eye cups were then transferred to a perfusion system that provided constant superfusion of oxygenated perfusate solution to the retina, enabling it to remain in a functional state in vitro. The ERG was recorded, as the retinal response to photic stimulation, from electrodes mounted within the perfusion system. The effects of insulin on the ERG were investigated by adding insulin to the perfusate solution. RESULTS: Application of insulin to the in vitro retina preparation decreased the amplitudes of the a- and b-waves of the ERG in a dose dependent manner with a maximal effect at doses of 0.1 U/ml and above. These effects were reversible. CONCLUSION: The reduction of ERG amplitudes may result from the hyperpolarising effect of insulin reported in other tissues. The findings suggest that insulin may have a regulatory role in retinal activity; however extrapolation of these results to the intact organism is dependent on the presence of insulin in retina.

Animals↗

PubMed1991

Phototherapy of posterior uveal melanomas.

The results of phototherapy on a small series of 19 patients with uveal melanomas are presented. Laser radiation at a wavelength of 620 to 630 nm was used in conjunction with a 5 to 7.5 mg/kg dose of haematoporphyrin derivative administered 24 hours before treatment, with total doses/treatment averaging 960 J/cm2. Eleven patients received two treatments, and one received a third. The longest duration of tumour control to 30 September 1990 was 31 months. Of the 19 patients treated six had complete regression of the tumour, while another five had minor to significant regression. A strong correlation between degree of regression and degree of tumour pigmentation was found, the lighter tumours responding much better than darker tumours. There were also strong indications that if a tumour did not respond to the initial phototherapy it was very unlikely that subsequent phototherapy would provide any further benefit.

Fluorescein Angiography↗

PubMed1988

Measurement of choroidal melanomas: a comparison of methods.

The prognosis for death from metastatic choroidal melanoma following enucleation has been shown to be strongly correlated with a number of risk factors of which the most important are age of onset, aggressive cell types and tumour volume. The advantages of enucleation for the treatment of choroidal melanomas are put into question by the singular lack of a parallel increase in life expectancy following this treatment, and evidence that it may promote the development of metastatic disease. Alternative forms of treatment have been introduced including observation of small and asymptomatic tumours. We are using a computer-aided system for serial measurement and statistical analysis of area and volume of choroidal melanomas. A comparison of results using our method and the conventional method of estimating volume by the product of basal area and height for 51 measurements on 15 eyes over a 6-month period showed an overestimation of volume by conventional methods which could be corrected by applying a "shape constant" determined by linear regression. Calculation of tumour growth rates is also shape-dependent, and a slowing in growth rate or even a reduction in melanoma size is possible.

Choroid Neoplasms↗