The sensory cells of the inner ear, hair cells, provide vertebrates with the ability to detect auditory stimuli and balance. In mammals, cochlear hair cells, those responsible for hearing, do not regenerate. Zebrafish hair cells do regenerate. Gaining an understanding of the role and regulation of the genes involved in the formation and regeneration of these cells may provide information important for the development of genetic therapies. We show that zebrafish atoh1 acts as the proneural gene responsible for defining the equivalence group from which hair cells form. Expression of atoh1 is dependent upon Fgf and Pax. Atoh1 induces expression of delta, resulting in activation of Notch and subsequent lateral inhibition. Another factor known to be important for hair cell formation in mice is Sox2. In zebrafish, sox2 expression is downstream of Atoh1, Notch and Fgf. Zebrafish Sox2 is not required for hair cell formation, but rather Sox2 is important for hair cell maintenance. In zebrafish, otic hair cell regeneration has not yet been characterized. We show that, following laser ablation, hair cells regenerate by way of transdifferentiation. We further show that this regeneration requires Sox2 activity. These data suggest that Sox2 acts to maintain support cell plasticity. This role is likely conserved because Sox2 is also important for stem cell plasticity in mammals. This new understanding of the role and regulation of both Atoh1 and Sox2 provides essential information that can be used to further efforts to provide genetic therapies for hair cell regeneration in mammals.

<p>We present core components of a hair modeling and dynamics solution for the feature film industry. Recent research results in hair simulation are exploited as a dynamics model based on solving the Euler-Lagrange equations of motion for a discretized Cosserat curve is implemented in its entirety. Solutions to the dynamics equations are derived and a framework for symbolic integration is outlined. The resulting system is not unconditionally positive definite but requires balanced physical parameters in order to be solvable using a regular linear solver. Several implementation examples are presented, as well as a novel modeling technique based on non-linear optimization.</p>

Thesis (Ph. D.)--University of Chicago, Committee-on-Developmental Biology, 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Chemistry." Includes bibliographical references (p.54-56).

Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 140-172).

Marginal zinc deficiency (MZD) exists in children of industrialized societies and can impair growth and development. Presently there are no data available on its global prevalence. It is believed that MZD is one of the most common hidden deficiencies throughout the world. This is partly because of the lack of sensitivity and specificity of serum zinc, the most commonly used biomarker of zinc status, to detect MZD . This deficiency in children is always accompanied by a decrease in hair zinc . Although in research settings hair zinc is a recognized biomarker of MZD in children, health practitioners do not presently use it. These cross-sectional studies were designed to examine the hair zinc status of preschoolers in Vancouver . They also aimed at exploring some dietary and non-dietary factors associated with hair zinc status in an attempt to construct and validate a screening tool for detection of MZD. Our first study indicated a mean hair zinc of 75±30 μg/g, with 46% below the cutoff (<70μg/g) for a group (n=87) of low-income preschoolers (Chapter II). Among these children we observed negative associations between the hair zinc and consumption of dairy (R² =0.09, P=0 .01) and milk (R² =0.08, P=0.01), being described as "often sick" (R² =0.55, P=0 .00) and "eating unhealthy" (R² =0.16 P=0.00), and prolonged breastfeeding (R² =0.11, P=0.01). Our citywide survey (n=719) indicated a mean hair zinc of 116±43 μg/g with 17% below the cutoff (Chapter III). Logistic regression analysis indicated sex, age, maternal education, the number of adults at home, consumption frequency of milk, "scores of activity level", "being described as frequently sick" and "taking supplements containing iron" as the significant predictors of hair zinc status . However, the final model had 16% sensitivity while having 98 .3% specificity, indicating its lack of usefulness as a screening tool. Our study provides important information on the hair zinc status of Vancouver preschoolers. Although we did not accomplish our primary goal of constructing and validating a screening tool, we did identify some factors in children and their environment associated with hair zinc, which may help in better understanding of hair zinc as a biomarker of MZD .

No description available.

No description available.

Marginal zinc deficiency (MZD) exists in children of industrialized societies and can impair growth and development. Presently there are no data available on its global prevalence. It is believed that MZD is one of the most common hidden deficiencies throughout the world. This is partly because of the lack of sensitivity and specificity of serum zinc, the most commonly used biomarker of zinc status, to detect MZD . This deficiency in children is always accompanied by a decrease in hair zinc . Although in research settings hair zinc is a recognized biomarker of MZD in children, health practitioners do not presently use it. These cross-sectional studies were designed to examine the hair zinc status of preschoolers in Vancouver . They also aimed at exploring some dietary and non-dietary factors associated with hair zinc status in an attempt to construct and validate a screening tool for detection of MZD. Our first study indicated a mean hair zinc of 75±30 μg/g, with 46% below the cutoff (<70μg/g) for a group (n=87) of low-income preschoolers (Chapter II). Among these children we observed negative associations between the hair zinc and consumption of dairy (R² =0.09, P=0 .01) and milk (R² =0.08, P=0.01), being described as "often sick" (R² =0.55, P=0 .00) and "eating unhealthy" (R² =0.16 P=0.00), and prolonged breastfeeding (R² =0.11, P=0.01). Our citywide survey (n=719) indicated a mean hair zinc of 116±43 μg/g with 17% below the cutoff (Chapter III). Logistic regression analysis indicated sex, age, maternal education, the number of adults at home, consumption frequency of milk, "scores of activity level", "being described as frequently sick" and "taking supplements containing iron" as the significant predictors of hair zinc status . However, the final model had 16% sensitivity while having 98 .3% specificity, indicating its lack of usefulness as a screening tool. Our study provides important information on the hair zinc status of Vancouver preschoolers. Although we did not accomplish our primary goal of constructing and validating a screening tool, we did identify some factors in children and their environment associated with hair zinc, which may help in better understanding of hair zinc as a biomarker of MZD .

Human hair is a relatively inert biopolymer and can survive through natural disasters. It is also found as trace evidence at crime scenes. Previous studies by FTIRMicrospectroscopy and – Attenuated Total Reflectance (ATR) successfully showed that hairs can be matched and discriminated on the basis of gender, race and hair treatment, when interpreted by chemometrics. However, these spectroscopic techniques are difficult to operate at- or on-field. On the other hand, some near infrared spectroscopic (NIRS) instruments equipped with an optical probe, are portable and thus, facilitate the on- or at –field measurements for potential application directly at a crime or disaster scene. This thesis is focused on bulk hair samples, which are free of their roots, and thus, independent of potential DNA contribution for identification. It explores the building of a profile of an individual with the use of the NIRS technique on the basis of information on gender, race and treated hair, i.e. variables which can match and discriminate individuals. The complex spectra collected may be compared and interpreted with the use of chemometrics. These methods can then be used as protocol for further investigations. Water is a common substance present at forensic scenes e.g. at home in a bath, in the swimming pool; it is also common outdoors in the sea, river, dam, puddles and especially during DVI incidents at the seashore after a tsunami. For this reason, the matching and discrimination of bulk hair samples after the water immersion treatment was also explored. Through this research, it was found that Near Infrared Spectroscopy, with the use of an optical probe, has successfully matched and discriminated bulk hair samples to build a profile for the possible application to a crime or disaster scene. Through the interpretation of Chemometrics, such characteristics included Gender and Race. A novel approach was to measure the spectra not only in the usual NIR range (4000 – 7500 cm-1) but also in the Visible NIR (7500 – 12800 cm-1). This proved to be particularly useful in exploring the discrimination of differently coloured hair, e.g. naturally coloured, bleached or dyed. The NIR region is sensitive to molecular vibrations of the hair fibre structure as well as that of the dyes and damage from bleaching. But the Visible NIR region preferentially responds to the natural colourants, the melanin, which involves electronic transitions. This approach was shown to provide improved discrimination between dyed and untreated hair. This thesis is an extensive study of the application of NIRS with the aid of chemometrics, for matching and discrimination of bulk human scalp hair. The work not only indicates the strong potential of this technique in this field but also breaks new ground with the exploration of the use of the NIR and Visible NIR ranges for spectral sampling. It also develops methods for measuring spectra from hair which has been immersed in different water media (sea, river and dam)