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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Role of oxidative stress in the balding dermal papilla

Upton, Jamie January 2012 (has links)
The dermal papillae of the hair follicle control its growth, differentiation and apoptosis via a range of growth factors. These secreted growth factors are known to differ between those of non-balding scalp and those of balding scalp and can even differ in response to a common stimuli – androgen. In balding scalp androgen stimulates the secretion of negative growth factors, while in non-balding scalp androgen is found to exert little or no effect. Dermal papilla cells (DPCs) can be cultured in vitro, however those from balding scalp have been found to undergo premature senescence compared to those from non-balding scalp. A major cause of premature senescence is oxidative stress – the gradual accumulation of reactive oxygen species within the cell causing deleterious loss of function. Reactive oxygen species are known to be mediated in response to androgens and growth factors and in turn may affect growth factor signalling within the cell. Using low oxygen cell culture as a means of reducing oxidative stress, balding and non-balding DPCs were grown and characterised. It was confirmed that low oxygen culture could increase proliferation, delay senescence and reduce reactive oxygen species with both DPC types and that balding DPCs showed a higher sensitivity to oxidative stress. It was also found that secretions of growth factors by the balding DPCs in response to different oxygen conditions differed greatly to that of the occipital DPCs. Androgen, but not TGF-β was found to modulate DPC production of catalase, an antioxidant, under low oxygen conditions and this caused a reduction in reactive oxygen species in the balding DPCs. Balding DPCs also demonstrated an upregulation of the antioxidant total glutathione, however had a reduced fraction of the active reduced form of the molecule. In addition, it was shown for the first time 3 that under cell culture conditions balding DPCs express TGF-β receptors and it was shown that proliferation and migration of the balding DPCs could be affected by addition of exogenous TGF-β, highlighting a potential role for TGF-β as an autocrine growth factor in the balding dermal papilla.
122

A comparison of DNA extraction methods from hair shafts: mitochondrial DNA analysis using next generation sequencing and nuclear DNA analysis using InnoQuant DNA quantification kit and InnoTyper 21 DNA typing kit

Kelleher, Anna 02 November 2017 (has links)
Forensic crime laboratories receive hair shafts as evidentiary samples and process them for DNA evidence as a means of identification of individuals. The Armed Forces DNA Identification Laboratory (AFDIL) provides DNA analysis to aid in the medico-legal death investigation of fallen service members and contributes to research and education in the field of forensic DNA analysis. The AFDIL receives hair samples from family members of service individuals as a reference standard as well as remains from both past and present day conflicts for identification. Often times nuclear DNA is too highly degraded in hair shafts to be obtained successfully. There are many more copies of mitochondrial DNA in a cell than nuclear DNA. Therefore, it is common practice to target mitochondrial DNA instead of nuclear DNA when processing a hair shaft for DNA evidence. Mitochondrial DNA also plays an important role at the AFDIL in familial identification when a self-reference standard is not available. The current validated protocol for extracting mitochondrial DNA (mtDNA) at the AFDIL is a manual digestion with a micro-tissue grinder followed by a 24-hour incubation step and an organic phenol-chloroform extraction. The first part of this study compares the currently validated organic extraction method with the new QIAGEN QIAamp® Fast DNA Tissue Kit extraction method. The QIAamp® Fast DNA Tissue Kit extraction is a mechanical, chemical, and enzymatic protocol involving a 2 mL disruption tube with a stainless steel bead which aides in disruption of the hair followed by a silica-column based purification. The QIAamp® Fast DNA Tissue Kit is a single day protocol which reduced lab processing time by more than half (7 hours to 3 hours). When results from six different hair samples extracted with the current organic method were compared with the same samples extracted with the QIAamp® Fast DNA Tissue Kit method, it was found that the two methods are comparable for mtDNA recovery, amplification, and sequencing. Recently, researchers at InnoGenomics© (New Orleans, LA) have developed nuclear DNA quantification and amplification kits that target small DNA fragments, creating the potential to obtain sufficient nuclear DNA data from samples containing highly degraded DNA. Instead of targeting loci that contain short tandem repeats (STRs), the InnoQuant™ DNA quantification kit and InnoTyper 21™ DNA typing kit (InnoGenomics©, New Orleans, LA) targets retrotransposable elements (REs). The second part of this study compares nuclear DNA extraction methods from hair shafts such as the QIAamp® Fast DNA Tissue Kit, a direct lysis procedure using ZyGEM® prepGEM™ enzyme, and direct lysis procedures using pronase. Nuclear DNA extracts were quantified InnoQuant™ and InnoTyper 21™ for DNA typing. Full profiles were obtained using the InnoTyper 21™ amplification kit from samples with as low as 0.0331 ng of DNA which were extracted with 0.05 mg/mL. However, no single extraction method demonstrated consistently higher DNA concentrations or more complete DNA profiles.
123

The role of hair follicles and Edar signalling in cutaneous wound healing

Garcin, Clare January 2016 (has links)
The Ectodysplasin/Ectodysplasin receptor (Eda/Edar) signalling pathway is critical during development for the formation of skin appendages. However, its roles during adulthood are only recently being elucidated. Adult appendages, such as hair follicles (HFs), are known to become activated to respond to cutaneous injury. However, the HF houses distinct cell populations that display differing capacities to participate and persist in re-epithelialisation. We show, contrary to previous findings, that the best-characterised stem cell (SC) niche within the HF (the bulge) does not respond to injury during the earliest stages of wound healing. We propose that bulge SCs are prevented from participating in early repair as a protection mechanism against tumourigenesis. Despite the bulge niche not participating in early repair, we found the upper HF outer root sheath (ORS) to respond rapidly to injury. Our investigation into the role of Eda/Edar signalling during wound healing revealed that activation of the pathway was able to specifically induce proliferation within this portion of the HF. We further demonstrate a number of roles for the Eda/Edar pathway during adult wound healing, including, surprisingly, influencing several wound responses within the dermis. Specifically, an absence of Eda/Edar signalling in Tabby mice results in delayed wound healing, whereas acute activation of the pathway in wild-type (WT) mice can stimulate re-epithelialisation and enhance wound repair. These effects also translate to a model of human wound healing, where activation of Eda/Edar signalling accelerates re-epithelialisation and increases peri-wound proliferation. RNA-seq analysis reveals diverse gene regulation in the presence/absence of Eda/Edar signalling. Overall, these findings suggest that manipulation of the Eda/Edar pathway may represent an attractive potential therapeutic for enhancement of wound repair, potentially through maximising the natural growth capacity of peri-wound HFs.
124

An appraisal of the use of numerical features in the forensic examination of hair

Brooks, Elizabeth M, na January 2007 (has links)
The advent of nuclear DNA (nuDNA) analysis altered the way forensic biology was both practised and viewed by the forensic biologists, police, the legal system and the general public. The ability of nuDNA to individualise analysis of evidence and attach a statistical frequency ratio to the result, created an expectation that numerical objectivity should be part of all forensic analysis. There are few scientists who would disagree with both the need and desirability of objective measures of their results. Forensic hair examiners are no exception as indicated by numerous scientific publications specifically discussing means of objectively assessing hair and its characteristics. While mitochondrial DNA offers a partially objective measure of hair the result is destructive of the sample. A method that objectively supports the hair analysts' microscopic findings and is non destructive would be beneficial to forensic hair examination. This project attempted to develop an objective measure of hair analysis by using both traditional light microscopic comparative techniques combined with a high end digital imaging and image analysis capacity. Where objectivity equals an empirical set of numbers that can be manipulated for statistical significance, the comparative biological sciences such as histology, anthropology and forensic hair examination struggle. Forensic hair examiners have long acknowledged the difficulty, even inability, of assigning numerical values to the features that characterise one hair as being different from another. The human scalp hair is a "morphological" unit that is not readily split into component parts or even that these parts lend themselves to a number value. There have been at least nine separate studies which favourably compare the specificity of microscopic hair examinations. The challenge this study addressed was to appraise the use of numerical features in forensic hair examination, with particular emphasis on those features currently resisting numerical evaluation; specifically, colour and pigmentary characteristics. The techniques used were based on obtaining high quality digital images, and using the pixels inherent in the images to obtain numerical values of such features as colour and pigmentation. The project sample was taken from the telogen scalp hairs obtained from the hairbrushes of ten nominally brown haired Caucasians, both male and female. The focus was twofold: o Compare colour analysis of hair images from brown haired Caucasians within three standard, internationally recognized colour models, namely Red-Green-Blue (RGB) colour model; CIE XYZ Tristimulus (1931) colour model; and CIE L*a*b* (1976) colour model. o Using the same sets of digital images, undertake pattern recognition analysis both intra and inter individual hair samples. Discriminate analysis of the mean colour values collected for each of the inherent colour variables in the three colour models (red, green, blue; X, Y, Z and L*, a*, b*) indicated the RGB colour model gave the least separation of brown haired individuals; CIE XYZ and CIE L*a*b* separated several individuals for all their individual samples and several other individuals were mostly separated with only one of their own samples overlapping with another. Pattern analysis used a small area that represented the overall pigment patterning observed along the length of the hair shaft. This area was extracted from the digital image within V++ Digital Optics image analysis software. The extracted pattern piece was then compared with other sample images within the same hair and four other hairs from the same individual. Pattern extracts were also compared between person hair samples. The comparisons generated a set of numerical values based on the pixel number on the "x" axis of the whole image and the average difference between the extracted pattern image and the whole image. Analysis of this data resulted in log distributions when persons were matched with themselves. It was also possible to refer an unknown pattern extract to this distribution and based on probabilities, predict as to whether or not the unknown sample fell within any of the known sample's distribution.
125

Using stable-isotope analysis to obtain dietary profiles from old hair

Roy, Diana Milantia 23 September 2002 (has links)
Stable isotope analysis of human tissue can provide information about diet independent of artifactual remains. Food is broken down and used in the synthesis of body tissue, so the isotopic composition of hair keratin reflects the isotopic composition of foods consumed. Therefore, the analysis of hair can provide a window into broad dietary practices, and this view can supplement the information that is inferred from artifacts such as hunting tools and hearths. This project details the use of historic Plains Indians hair as a sample material for carbon and nitrogen isotope analysis. A minimum specimen size of a 2-cm (l00- 150 μg) segment of a strand was established. This indicates that small hair fragments found in archeological excavations can be informative. It also allowed the testing of up to 12 sequential segments from strands up to 24 cm long. Since hair grows about 1 cm per month, a 24-cm strand provided about a 2-yr record of isotopes and diet. The isotopic variations along some strands were as high as 0.49‰ for δ¹⁵N and 1.05‰ for δ¹³C, exceeding the background analytical uncertainty of 0.22‰ for δ¹⁵N and 0.2l‰ for δ¹³C. Differences between individuals and between population groups also exceeded this background level, validating the use of this isotope technique in discriminating isotopic differences between hairs and between people. No isotopic differences were found between males and females, and no isotopic differences were found based on the age of the individual. This suggests that there are no physiological differences by gender or age affecting isotope metabolism, which means that should a study find an isotopic difference between men and women, it would reflect dietary differences, not physiological ones. Isotope testing produced distinct isotope profiles (δ¹⁵N vs. δ¹³C) for two cultural groups, the Lower Brule reservation Sioux of 1892 and the reservation Blackfoot of 1892 and 1935. The resultant dietary profiles indicate a higher consumption of meat by the Blackfoot and a higher consumption of corn by the Lower Brule. The two groups of Blackfoot fit into the same profile despite the passage of several decades. This raises the possibility that stable isotope analysis can also be used to identify members of the same cultural population. / Graduation date: 2003
126

Detection of Prenatal Opiate Exposures in Alternative Matrices

Moller, Monique 12 January 2011 (has links)
Identification of maternal opioid abuse in pregnancy is often difficult to ascertain in the absence of reliable self report. For this reason, physicians and child protection workers often turn to maternal and neonatal hair analysis for the detection of in utero opioid exposures. Since neonatal opiate hair analysis continues to prove difficult due to the scarcity of the hair sample and low drug concentrations, I developed a sensitive method utilizing headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) for the detection of three principal opiates (morphine, codeine, and 6-monoacetylmorphine) in human hair. Moreover, I characterized an at-risk neonatal population for in utero opiate exposures as well as for other drugs of abuse and alcohol. Equipped with a sensitive and specific method for the detection of opiate exposures and understanding the addiction profiles of pregnant women may lead to better clinical and social management and may benefit an at-risk population.
127

Detection of Prenatal Opiate Exposures in Alternative Matrices

Moller, Monique 12 January 2011 (has links)
Identification of maternal opioid abuse in pregnancy is often difficult to ascertain in the absence of reliable self report. For this reason, physicians and child protection workers often turn to maternal and neonatal hair analysis for the detection of in utero opioid exposures. Since neonatal opiate hair analysis continues to prove difficult due to the scarcity of the hair sample and low drug concentrations, I developed a sensitive method utilizing headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) for the detection of three principal opiates (morphine, codeine, and 6-monoacetylmorphine) in human hair. Moreover, I characterized an at-risk neonatal population for in utero opiate exposures as well as for other drugs of abuse and alcohol. Equipped with a sensitive and specific method for the detection of opiate exposures and understanding the addiction profiles of pregnant women may lead to better clinical and social management and may benefit an at-risk population.
128

Population patterns of hair zinc, dietary and socio-demographic determinants

Vaghri, Ziba 05 1900 (has links)
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 ��g/g, with 46% below the cutoff (<70��g/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 (R�� =0.09, P=0 .01) and milk (R�� =0.08, P=0.01), being described as "often sick" (R�� =0.55, P=0 .00) and "eating unhealthy" (R�� =0.16 P=0.00), and prolonged breastfeeding (R�� =0.11, P=0.01). Our citywide survey (n=719) indicated a mean hair zinc of 116��43 ��g/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.
129

"I am Not my Hair! Or am I?": Black Women's Transformative Experience in their Self Perceptions of Abroad and at Home

Chapman, Yolanda Michele 28 November 2007 (has links)
The Black female body has been subject to cultural scripting in which Black women are deemed as the "other." This representation of the Black female is played out in many ways such as through the racial and racist marking of her hair and skin color. In investigating Black women who have participated in a study abroad program, I found that this is one vehicle in which they have been exposed to other's perspectives of the Eurocentric standards of beauty. In this paper, I have examined ways in which Black women are active agents in their own social scripting of their bodies. Through interviews, focus groups and participant observation, with 20 self identified Black women, the investigation began with a look at the African and European cultural influences on African American ideas about beauty, hair and identity. Initial discussions of participants' experiences with hair at home and abroad led to broader dialogues about transformations in their concepts of gender, race, and identity.
130

Olika empati för kvinnliga brottslingar med olika hårfärg

Edvardsson, Petrah January 2013 (has links)
Det finns stereotyper om kvinnor med olika hårfärg och stereotyper påverkar människors empati och bedömning. Därför gjordes ett kvasiexperiment där det undersöktes om en kvinnlig brottsling väcker olika mycket empati beroende på (a) vilken hårfärg hon har och (b) empatisörens kön. I studien deltog 132 personer, varav 61 kvinnor och designen var en enkät där experimentgruppen fick läsa om en gärningskvinna som antingen var blond, brunhårig, svarthårig eller rödhårig och därefter skatta empati utifrån Batsons empatiskala. Resultaten visade att (a) blondiner väcker minst empati medan rödhåriga väcker mest (b) kvinnor  känner högre empati än män och (c) empati stiger med åldern. Dessa resultat förklarades bland annat med att blondiner mer än rödhåriga ses som objekt i samhället och är därför mindre empativäckande, att kvinnor i högre grad än män förväntas vara empatiska då det är detta beteende som förväntas av kvinnorollen samt att empati är något som utvecklas med tiden.

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