Lack of hair due to alopecia or skin grafting procedures causes significant distress due to hair's role in social and sexual communication. Only limited pharmacological agents are currently available to stimulate hair growth; their development is hampered by inappropriate model systems. Most research involves large terminal scalp follicles rather than the clinical targets of tiny vellus or intermediate follicles. The overall aim of this thesis was to develop a novel model system based on intermediate hair follicles. Initially, intermediate follicles from female pre-auricular skin were characterised and compared to matched terminal follicles. Intermediate follicles were smaller, less pigmented, shorter and possessed a more 'tubular' bulb morphology than their more 'bulbous' terminal counterparts. Significant correlations were demonstrated between various hair follicle measurements and corresponding dermal papilla diameters. Isolated terminal follicles grew significantly more than intermediate hair follicles in organ culture for 9 days. Testosterone (10nM), the major regulator of human hair growth, increased only intermediate follicle growth; the anti-androgen, cyproterone acetate (1μM), prevented this stimulation, unlike the 5α-reductase type 2 inhibitor finasteride (40ng/ml). Immunohistochemistry demonstrated androgen receptor and 5α-reductase type 2 proteins in both follicle types, while quantitative real-time PCR and gene microarray analysis detected their increased gene expression in intermediate follicles. Thus, smaller intermediate follicles showed major morphological and gene expression differences to terminal follicles in vivo and retained significant, biologically-relevant differences in vitro in organ culture including androgen-responsiveness. Therefore, intermediate hair follicles offer a novel, exciting, more clinically relevant, albeit technically difficult, model for future investigations into hair growth.

No / We examined multiple natural abundance isotope ratios of human hair to assess biological variability within and between geographic locations and, further, to determine how well these isotope values predict location of origin. Sampling locations feature differing seasonality and mobile populations as a robust test of the method. Serially-sampled hair from Cambridge, MA, USA, shows lower δ2 H and δ18 O variability over a one-year time course than model-predicted precipitation isotope ratios, but exhibits considerable differences between individuals. Along a ∼13° northsouth transect in the eastern USA (Brookline, MA, 42.3 ° N, College Park, MD, 39.0 ° N, and Gainesville, FL, 29.7 ° N) δ18 O in human hair shows relatively greater differences and tracks changes in drinking water isotope ratios more sensitively than δ2 H. Determining the domicile of humans using isotope ratios of hair can be confounded by differing variability in hair δ18 O and δ2 H between locations, differential incorporation of H and O into this protein and, in some cases, by tap water δ18 O and δ2 H that differ significantly from predicted precipitation values. With these caveats, randomly chosen people in Florida are separated from those in the two more northerly sites on the basis of the natural abundance isotopes of carbon, nitrogen, hydrogen, and oxygen. / This work was partially supported by the National Geospatial Agency under grant [HM1582-08-0024]. / Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, 11–15 May 2015, Vienna, Austria

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

The evaluation of the gloss of human hair, following wet/dry chemical treatments such as bleaching, dyeing and perming, has received much scientific and commercial attention. Current gloss analysis techniques use constrained viewing conditions where the hair tresses are observed under directional lighting, within a calibrated presentation environment. The hair tresses are classified by applying computational models of the fibres' physical and optical attributes and evaluated by either a panel of human observers, or the computational modelling of gloss intensity distributions processed from captured digital images. The most popular technique used in industry for automatically assessing hair gloss is to digitally capture images of the hair tresses and produce a classification based upon the average gloss intensity distribution. Unfortunately, the results from current computational modelling techniques are often found to be inconsistent when compared to the panel discriminations of human observers. In order to develop a Gloss Evaluation System that produces the same judgements as those produced from both computational models and human psychophysical panel assessments, the human visual system has to be considered. An image based Gloss Evaluation System with gonio-capture capability has been developed, characterised and tested. A new interpretation of the interaction between reflection bands has been identified on the hair tress images and a novel method was developed to segment the diffuse, chroma and specular regions from the image of the hair tress. A new model has been developed, based on Hunter's contrast gloss approach, to quantify the gloss of the human hair tress. Furthermore, a large number of hair tresses have been treated with a range of hair products to simulate different levels of hair shine. The Tresses have been treated with different commercial products. To conduct a psychophysical experiment, one-dimensional scaling paired comparison test, a MATLAB GUI (Graphical user interface) was developed to display images of the hair tress on calibrated screen. Participants were asked to select the image that demonstrated the greatest gloss. To understand what users were attending to and how they used the different reflection bands in their quantification of the gloss of the human hair tress, the GUI was run on an Eye-Tracking System. The results of several gloss evaluation models were compared with the participants' choices from the psychophysical experiment. The novel gloss assessment models developed during this research correlated more closely with the participants' choices and were more sensitive to changes in gloss than the conventional models used in the study.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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