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Biomedical subjects

E A Hill

Publications and source records attributed to E A Hill.

7 recordsLinked to original sources
PubMed2005

Incidence of keratitis of varying severity among contact lens wearers.

AIM: To determine the incidence of non-severe keratitis (NSK) and severe keratitis (SK) among wearers of current generation contact lenses. METHODS: A 12 month, prospective, hospital based epidemiological study was conducted by examining all contact lens wearers presenting with a corneal infiltrate/ulcer to a hospital centre in Manchester. A clinical severity matrix was used to differentiate between NSK and SK, based on the severity of signs and symptoms. The size of the hospital catchment population and the wearing modalities (daily wear (DW) or extended wear (EW)) and lens types being used were estimated from relevant demographic and market data. RESULTS: During the survey period, 80 and 38 patients presented with NSK and SK, respectively. The annual incidences (cases per 10,000 wearers) for each wearing modality and lens type were: DW rigid--NSK 5.7, SK 2.9; DW hydrogel daily disposable--NSK 9.1, SK 4.9; DW hydrogel (excluding daily disposable)--NSK 14.1, SK 6.4; DW silicone hydrogel--NSK 55.9, SK 0.0; EW rigid--NSK 0.0, SK 0.0; EW hydrogel--NSK 48.2, SK 96.4; EW silicone hydrogel--NSK 98.8, SK 19.8. The difference in SK between EW hydrogel and EW silicone hydrogel was significant (p = 0.04). CONCLUSIONS: A clinical severity matrix has considerable utility in assessing contact lens related keratitis. There is a significantly higher incidence of SK in wearers who sleep in contact lenses compared with those who only use lenses during the waking hours. Those who choose to sleep in lenses should be advised to wear silicone hydrogel lenses, which carry a five times decreased risk of SK for extended wear compared with hydrogel lenses.

Adult↗
PubMed1980

Dosage uniformity in hydrocortisone ointment B.P.

The content uniformity of hydrocortisone in seven commercially available brands of hydrocortisone ointment B.P. 1% has been investigated. Fifty 5 mg samples were assayed by high pressure liquid chromatography and the results indicated that for 95% confidence levels only two of the ointments exhibited no positive skewness, one exhibited a significant degree of positive skewness and four exhibited a highly significant degree of positive skewness. The extent of the skewed distributions is discussed in relation to previously published particle/agglomerate distributions for these ointments. The content uniformity in terms of the coefficient of variation CE calculated from the h.p.l.c. data is compared with the coefficient of variation CP that can be predicted from mixing theory on the basis of the particle/agglomerate distribution of the hydrocortisone. The departure from normality in drug content uniformity in the ointment is attributed to the hydrocortisone particles not being individually available for randomization, a large number being in an agglomerated form. That is, the manufacturing process is failing to achieve the full potential of the formulation by dispersing all of the agglomerates. Theoretical and experimental models predict that percutaneous absorption of drug may be enhanced over areas, where agglomerates are located, possibly not only resulting in localized toxicity but increased systemic availability. Drug content variability in small samples (5 mg) of topical steroid formulations could also effect the degree of skin blanching response in Mackenzie-Stoughton type tests since 5 mg portions containing in excess of twice the labelled strength were found. Regulatory control of content uniformity should be considered for certain topical steroids if unintentional over-dosage on small discrete areas is to be avoided.

Administration, Topical↗
PubMed1975

Identification of strains of herpes simplex virus by comparison of the density of their DNA using the preparative ultracentrifuge.

The buoyant densities of the DNA of herpes simplex virus type 1, type 2 and Pseudorabies virus, as determined in the analytical ultracentrifuge, are 1.725, 1.727 and 1.731 correlating with G+C contents of 67, 69 and 73 per cent respectively. The density differences for the DNA's of type 1 and type 2 herpes simplex viruses have been confirmed in experiments with isotopically labelled DNA from four type 1 and six type 2 strains by preparative CsCl gradient ultracentrifugation. The DNA of all the type 2 strains was denser than that of any of the type 1 strains examined. Despite these differences in DNA base composition of type 1 and type 2 strains, nearest neighbour analysis of their DNA's disclosed no obvious differences in doublet pattern or general design.

Base Sequence↗