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Biomedical subjects

Paul Stevenson

Publications and source records attributed to Paul Stevenson.

5 recordsLinked to original sources
PubMed2005

Remarks on the shear viscosity of surfaces stabilised with soluble surfactants.

A survey is made of previously reported values of the surface shear viscosity of sodium dodecyl sulphate solution which reveals inconsistencies. The origin of these inconsistencies is thought to be due to the fact that, because SDS is a soluble surfactant, the surface deformation rate is governed by a three-dimensional sublayer adjacent to the surface and is therefore inherently experiment-dependent. Because of this, only an apparent surface shear viscosity that is specific to a particular experiment can be measured. However, for an insoluble surfactant, an intrinsic two-dimensional surface viscosity can be clearly defined. Some methods of measuring an apparent surface shear viscosity assume that the surface shear viscosity is the only surface property that determines the drainage rate from foam or individual Plateau borders but there is experimental evidence to show that other surface properties may be significant.

Letter↗
PubMed2005

A multicenter study of the pharmacokinetics of tacrolimus ointment after first and repeated application to children with atopic dermatitis.

The pharmacokinetics of tacrolimus after first and repeated application of 0.1% tacrolimus ointment were evaluated in 39 children, aged 6-12 y, with moderate to severe atopic dermatitis. The patients were grouped according to the size of the affected body surface area to be treated: Group 1< or =1500 cm(2); Group 2 >1500 cm(2) < or =3000 cm(2); Group 3 >3000 cm(2) < or =5000 cm(2). Serial blood samples to calculate pharmacokinetic parameters taken on Day 1 (first ointment application) and Day 14 (last application) showed minimal systemic exposure to tacrolimus. Overall, 92% of the blood samples assayed contained tacrolimus concentrations below 1 ng per mL and 17% of samples were below 0.025 ng per mL, the lower limit of quantification. Systemic exposure to tacrolimus varied between patients and tended to increase proportionally as the size of the treated body surface area increased. Absorption decreased with time as the skin lesions healed and there was no evidence of systemic accumulation. The mean apparent half-life of tacrolimus (t(1/2, z)) was 66+/-27 h (range 19-125 h). Most patients experienced substantial clinical improvement in their atopic dermatitis. There were no clinically relevant changes in laboratory values, and the most frequently reported adverse event was skin burning, which resolved quickly as the skin condition improved.

Administration, Topical↗
PubMed2005

Pharmacokinetics of 0.1% tacrolimus ointment after first and repeated application to adults with moderate to severe atopic dermatitis.

The systemic exposure to tacrolimus after first and repeated application of 0.1% tacrolimus ointment was investigated in 32 adults with moderate to severe atopic dermatitis. Patients were allocated to treatment groups according to the size of the affected area to be treated: Group 1</=3000 cm(2) (N=11); Group 2>3000 cm(2)</=6000 cm(2) (N=12); Group 3>6000 cm(2)</=10,000 cm(2) (N=9). Ointment was applied twice daily for 13 d and once daily on Day 14; the size of application area remained the same irrespective of healing. Blood samples were collected on Days 1 (first application), 4, and 14 (last application) and analyzed by a validated HPLC-MS/MS method. Systemic exposure to tacrolimus was generally low with 96% of blood samples assayed containing concentrations below 1 ng per mL and 23% of samples below the lower limit of quantification (0.025 ng per mL). Peak concentrations after first ointment application were </=2.8 ng per mL, and the mean area under the concentration-time curve between 0 and 12 h using the trapezoidal rule (AUC(0-12)) values were 1.1, 1.6, and 4.8 ng h per mL for Groups 1, 2, and 3, respectively. The corresponding mean values on Day 14 were similar indicating negligible systemic accumulation of tacrolimus after repeated ointment applications. Both the rate and extent of topical absorption decreased as the skin lesions healed.

Administration, Cutaneous↗
PubMed2003

Merging the managed care cycle and revenue cycle to meet strategic goals.

By integrating the functions of the managed care cycle and the revenue cycle, providers can more readily obtain appropriate payment. The managed care cycle emphasizes strategy, while the revenue cycle emphasizes day-to-day business functions. The four phases of the managed care cycle are interlinked. Management requires information obtained from the revenue cycle to decide upon action needed in the managed care cycle.

Accounts Payable and Receivable↗