Technical approaches to select high-performance instant skin smoothing formulations: Correlation of in vitro and in vivo assessment methods.

BACKGROUND: Contractile films that smooth the surface of skin upon drying are popular among consumers due to their "instant" effect and perceivable smoothing benefits. The objective of our study was to correlate an in vitro measurement of contractile force with in vivo smoothing performance, thereby enabling rapid screening of film-forming technologies for impactful cosmetic results. METHODS: We introduce and characterize an in vitro method to measure drying stress of film-containing formulations. This method is used to measure the drying stresses of seven different cosmetic film formulations. We then evaluate these formulas in a blinded clinical study, measuring their effect on under-eye and Crow's Feet area smoothing through bioinstrumentation (3D PRIMOS imaging) and blinded expert grading of images. RESULTS: The in vitro drying stress measurement was found to be repeatable and sensitive enough to detect differences between formulations with typical amounts of film-forming agents. Significant correlation was found between the in vitro drying stress measurements and under-eye smoothing measured by 3D imaging (R2  = 0.71). Expert grading confirmed that film formulas deliver perceivable smoothing in the under-eye and Crow's Feet regions 15 minutes after application. CONCLUSION: The in vitro method described here can be used to predict the efficacy of formulations that deliver smoothing benefits to consumers. For consumer use, the esthetic properties of a formula should be balanced with film performance, guided by this model which predicts skin smoothing efficacy.

Photoprotection against visible light-induced pigmentation.

OBJECTIVE: This paper presents in vivo an in vitro studies demonstrating the induction of pigmentation in human skin by visible light which can be blocked by using formulation containing the correct amount of yellow iron oxide (YIO). METHODS: An in vitro absorption method was developed to determine the protection provided by a test formulation containing 4.5% YIO using an IPD UVA-VIS action spectrum. Following the development of the in vitro method and in vivo study with 10 normal healthy volunteers with Fitzpatrick skin phototypes IV to VI was conducted to verify if the predictive model. RESULTS: The in vitro model for visible light protection provided a protection factor of 2.5 using the in vitro absorption spectrum of 4.5% of YIO with a very similar result from the in vivo study with a protection factor of 3.0. Multiple daily exposures of visible light have shown increase in skin pigmentation and the application of YIO provide less development of pigmentation when compared to unprotected skin. CONCLUSION: In vitro testing of the absorbance of the pigmented formulation using a proposed action spectrum for immediate pigment darkening (IPD) response in the visible light range supports the in vivo protection observations for persistent pigment darkening (PPD) and can be used as predictor for skin pigmentation induced by visible light.

Factors influencing the reproduction and production performance of the Nguni cattle ecotypes in South Africa.

The objective of this experiment was to assess the reproductive and productive performance of Nguni cattle distributed among 11 farms in four regions of South Africa. Only data of registered Appendix A to Stud Proper Nguni animals from the Agricultural Research Council of South Africa's database were used. Data were collected from 2061 dams and 3285 calves between 1990 and 2009. Overall means for age at first calving (AFC) and calving intervals (CI) were 33.79 ± 4.90 months and 400.29 ± 78.70 days, respectively. Dry season-born heifers had lower AFC than wet season-born heifers. Dry seasons 4 and wet seasons 1 had lower CI than seasons 2 and 3, indicating that conceptions take place between December and May. Average growth weights of calves were 24.87 ± 3.13, 151.91 ± 21.09, 169.25 ± 23.68 and 237.96 ± 27.34 kg at birth (BW), weaning (WW), 12 months (YW) and 18 months of age, respectively. BW was higher in dry seasons 4 and wet seasons 1; WW and YW were higher in dry than in wet seasons. This is the first study demonstrating that performance of Nguni cattle is influenced by ecological regions of the dam's origin, year-season of birth/calving, breeder's management, parity and herdbook status, confirming that environment-genotype interactions influence the performance of Nguni cattle in southern Africa. This stimulated a follow-up study on the use of geographic information systems to specifically identify factors influencing the reproductive and productive performance of Nguni cattle in southern Africa.