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Biomedical subjects

K S Ryatt

Publications and source records attributed to K S Ryatt.

27 records · Page 2Linked to original sources
PubMed1983

The usefulness of reflectance spectrophotometric measurements during psoralens and ultraviolet A therapy for psoriasis.

Reflectance spectrophotometry was used to obtain indices of the hemoglobin and melanin content of psoriatic lesions and adjacent clinically normal skin in thirteen patients undergoing photochemotherapy. The pretreatment lesional hemoglobin index was 2.8 times greater than that of adjacent uninvolved skin. With therapy, this index decreased rapidly initially, and during the second or third week approached that of the uninvolved skin. The ratio of lesional and uninvolved skin hemoglobin indices decreased to approximately 1.3, and continuation of PUVA treatment failed to reduce it further. Termination of treatment at this stage, which occurs before clinical resolution, resulted in subsequent clearance of psoriasis. The decrease in the lesional hemoglobin index and the clearance time appeared to be dose-dependent, and, indeed, a more aggressive regimen resulted in approximately 50% reduction in both the number of treatments and the cumulative dose required to achieve a stable hemoglobin index ratio and subsequent clinical clearance.

Adult↗
PubMed1983

The effect of serial dilution of betamethasone-17-valerate on blanching potential and chemical stability.

The effect of serial dilution of betamethasone-17-valerate (Betnovate ointment) in Unguentum Merck was investigated using a single application blanching assay in 10 subjects and high performance liquid chromatography. There was no statistically significant difference between any of the diluted formulations with regard to blanching potential. Chemical stability was maintained following a 1:32 dilution for 2 months and 1:4 dilution for 5 months at least, after storage at room temperature.

Betamethasone↗
PubMed1982

The stability and blanching efficacy of betamethasone-17-valerate in emulsifying ointment.

The bio-availability of betamethasone-17-valerate (Betnovate ointment) in emulsifying ointment (1 in 4 dilution) was investigated in ten subjects using a single-application vasoconstrictor assay; the blanching induced was measured using a skin reflectance spectrophotometer. The vasoconstrictor activity of the diluted preparations decreased with age. There was no significant difference between the vasoconstrictor activity of freshly made Betnovate 1 in 4 in emulsifying ointment and undiluted Betnovate ointment, and between 3-4 week old diluted Betnovate and emulsifying ointment base. Blanching induced by freshly prepared 4, 8 and 16-fold dilutions was not significantly different but a large reduction in blanching occurred on diluting 32-fold with emulsifying ointment. The degradation of betamethasone -17-valerate in emulsifying ointment was quantified by high performance liquid chromatography. More than 60% of the betamethasone -17-valerate underwent degradation within 6 h. There was a simultaneous increase in the concentration of betamethasone-21-valerate which peaked within 2 days and was followed by a slow degradation (half-life 8 days) to betamethasone free alcohol.

Betamethasone↗
PubMed1982

Keratosis lichenoides chronica.

Keratosis lichenoides chronica is characterized by violaceous, papular and nodular lesions typically arranged in a linear and reticulate pattern, most marked on the hands and feet, and accompanied by a seborrhoeic dermatitis-like eruption of the face. This rare condition is very refractory to treatment but we report a patient whose eruption responded top photochemotherapy.

Adolescent↗
PubMed1982

Reflectance spectrophotometric quantification of skin colour changes induced by topical corticosteroid preparations.

Reflectance spectrophotometry was used to observe the degree of vasoconstriction induced by topically applied corticosteroids. The average blanching effectiveness of the corticosteroid preparations as determined by this technique was the same as that found by other workers using subjective assessments. Reflectance spectrophotometry can be utilized to quantify the degree of vasoconstriction produced by local corticosteroids applied to the skin and is particularly suitable for measuring the response of individual subjects.

Administration, Topical↗