Biomedical subjects
Publications and source records attributed to J I McGill.
In previous studies adenine arabinoside and trifluorothymidine were found to be equally effective treatments for dendritic ulcers of the cornea, but a trend emerged which suggested that in amoeboid ulcers trifluorothymidine was more effective. The collection of additional cases confirms the superiority of trifluorothymidine in such cases.
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Blood lactate concentration has been measured at intervals over a twelve hour period in four maturity-onset diabetics with retinopathy treated by sulphonylurea and phenformin therapy. Despite moderately good control of blood glucose, all four patients had markedly elevated concentrations of blood lactate (12h means of 2.1-2;4 mmol/1) with concentrations greater than 3 mmol/1 at some time during the day. Hepatic function was normal in all patients and in all four patients plasma creatinine was 80-85 mumol/1, (normal range 60-125 mumol/1) so that the usual indications for not using biguanides were absent. It is concluded that diabetics with retinopathy constitute a group of patients with an increased risk of phenformin-associated lactic acidosis, and that plasma creatinine estimation may be unreliable in assessing whether patients are suitable for phenformin therapy.
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The clinical differentiation of corneal epithelial lesions due to herpes simplex or herpes zoster may be confusing. Practical clinical tests, including the use of topical ocular stains, are useful to differentiate corneal epithelial lesions caused by these two viruses. Two distinctive types of zoster corneal epithelial disease may be seen; an early dendritic form, and a delayed form characterized by corneal mucus plaques that may take a dendriform pattern. These plaques are composed of mucus that is adherent to swollen, degenerating epithelial cells. The clinical differentiation between these two viruses is essential since topically applied corticosteroids are contraindicated in epithelial herpes simplex and often are indicated in the management of epithelial herpes zoster.
The 50% infectious dose of a preparation of herpes simplex virus was measured in eyes of rabbits by a multiple corneal inoculation method. One hour after inoculation of virus, one eye was treated with drops of human leukocyte interferon, and the other was treated with saline or with a different dose of interferon. Results from groups of three to four rabbits were combined for analysis. Treatment reduced the 50% infectious dose of virus in proportion to the concentration of interferon applied (within the range of 6.5 X 10(4)-1.3 X 10(6) units/ml) and not according to the total number of units instilled. Different treatment schedules were tried. Two applications of interferon each day were as effective as eight applications at intervals of 15 min or 1 hr. One application produced near-maximal antiviral effects for 18-24 hr. Thus, in human herpetic keratitis, a single daily application of the most concentrated available preparation of human interferon might be the most efficient schedule of treatment.
One hundred two unselected patients with ulceration of the cornea due to herpes simples virus were treated with either adenine arabinoside or trifluorothymide; the trial was double-blind, stratified, and radomized. The two drugs were given topically five times per day, and the rate of healing was observed and recorded. The series included 87 patients with dendritic ulcers and 15 with amoeboid ulcers. Dendritic ulcers of the cornea can be accurately measured, and the healing process can be easily followed. In this situation no statistically significant difference between the efficacy of adenine arabinoside and that of trifluorothymidine was demonstrated. Amoeboid ulcers are more difficult to evaluate than dendritic ulcers, and their responses to treatment vary considerably; however, data from this small group of patients suggest that trifluorothymodine may be more effective than adenine arabinoside for the treatment of amoeboid ulcers.
Exudative retinal detachment and oedema of the posterior retina are well-recognized clinical entities for which a cause is rarely found. Scleritis may cause both these clinical syndromes by a spread of inflammation from the sclera into the uveal tract. Although treatment may result in a rapid resolution of scleritis, retinal detachment and macular oedema persist and prove extremely resistant, even to high doses of systemic steroids. Recovery may be incomplete and may occur only after weeks or months of treatment.
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Ara-A is an effective antiviral agent in the treatment of herpetic ulceration. Its use leads to a quick and high cure rate, and clinical resistance is low. It can successfully be used in cases showing complications after treatment with other antiviral agents.