Determinants of Hair Manganese, Lead, Cadmium and Arsenic Levels in Environmentally Exposed Children.

Biomarkers of environmental metal exposure in children are important for elucidating exposure and health risk. While exposure biomarkers for As, Cd, and Pb are relatively well defined, there are not yet well-validated biomarkers of Mn exposure. Here, we measured hair Mn, Pb, Cd, and As levels in children from the Mid-Ohio Valley to determine within and between-subject predictors of hair metal levels. Occipital scalp hair was collected in 2009-2010 from 222 children aged 6-12 years (169 female, 53 male) participating in a study of chemical exposure and neurodevelopment in an industrial region of the Mid-Ohio Valley. Hair samples from females were divided into three two centimeter segments, while males provided a single segment. Hair was cleaned and processed in a trace metal clean laboratory, and analyzed for As, Cd, Mn, and Pb by magnetic sector inductively coupled plasma mass spectrometry. Hair Mn and Pb levels were comparable (median 0.11 and 0.15 µg/g, respectively) and were ~10-fold higher than hair Cd and As levels (0.007 and 0.018 µg/g, respectively). Hair metal levels were higher in males compared to females, and varied by ~100-1000-fold between all subjects, and substantially less (<40-70%) between segments within female subjects. Hair Mn, Pb, and Cd, but not As levels systematically increased by ~40-70% from the proximal to distal hair segments of females. There was a significant effect of season of hair sample collection on hair Mn, Pb, and Cd, but not As levels. Finally, hair metal levels reported here are ~2 to >10-fold lower than levels reported in other studies in children, most likely because of more rigorous hair cleaning methodology used in the present study, leading to lower levels of unresolved exogenous metal contamination of hair

Hair radioactivity as a measure of exposure to radioisotopes

Since many radioisotopes accumulate in hair, this tropism was investigated by comparing the radioactivity of shaved with plucked hair collected from rats at various time intervals up to 24 hrs after intravenous injection of the ecologically important radioisotopes, iodine-131, manganese-54, strontium-85, and zinc-65. The plucked hair includes the hair follicles where biochemical transformations are taking place. The data indicate a slight surge of each radioisotpe into the hair immediately after injection, a variation of content of each radionuclide in the hair, and a greater accumulation of radioactivity in plucked than in shaved hair. These results have application not only to hair as a measure of exposure to radioisotopes, but also to tissue damage and repair at the hair follicle

Alopecia areata: a multifactorial autoimmune condition

Alopecia areata is an autoimmune disease that results in non-scarring hair loss, and it is clinically characterised by small patches of baldness on the scalp and/or around the body. It can later progress to total loss of scalp hair (Alopecia totalis) and/or total loss of all body hair (Alopecia universalis). The rapid rate of hair loss and disfiguration caused by the condition causes anxiety on patients and increases the risks of developing psychological and psychiatric complications. Hair loss in alopecia areata is caused by lymphocytic infiltrations around the hair follicles and IFN-γ. IgG antibodies against the hair follicle cells are also found in alopecia areata sufferers. In addition, the disease coexists with other autoimmune disorders and can come secondary to infections or inflammation. However, despite the growing knowledge about alopecia areata, the aetiology and pathophysiology of disease are not well defined. In this review we discuss various genetic and environmental factors that cause autoimmunity and describe the immune mechanisms that lead to hair loss in alopecia areata patients

Beauty is Pain: Black Women’s Identity and Their Struggle with Embracing Their Natural Hair

In the United States Black hair is viewed negatively because of its difference. Black females often deal with societal pressures to alter their kinky, curly hair from its natural state. To date, the social pressure of adopting a more Eurocentric (reflective of European descent—such as long, straight hair) look begins at an early age through socialization. The Eurocentric beauty standard plays a huge role in Black women’s positive self-identity and their perceptions of their own beauty. At an early age, specifically between ages three and four, African American children have a good understanding of what “good” hair means and the social hierarchy it can create for themselves (Bellinger 2007). Black females are constantly told that they have “nappy” or “bad hair” and begin to internalize self-hatred. Theorists suggest, that this self-hatred journey begins at home, as a result of constantly being teased about their tight curly coils from many sources and close ties. As a result Black women receive messages that “nappy” hair is undesirable (Robinson 2011). In addition, Black females often have their hair straightened, relaxed, or chemically altered because of the societal pressures that remind them that their hair in its natural state is not acceptable or presentable in society (White 2005). One can argue that this is the case for the majority of Black females with “wild” curly hair, who have a weekly ritual, spend hundreds of dollars, and spend numerous hours trying to attain the White western ideal image. This is problematic in the Black community because Black women are constantly oppressed and devalued based on their physical appearance, essentially being brainwashed into erasing their cultural identity. This is detrimental to the Black community due to the fact that Blacks are encouraged further distance themselves from their cultural roots, while forcing Blacks to abandon their African hair traditions (Randle 2015). In this paper, “good hair” is defined as hair that minimizes African ancestry and is more reflective of a European, Native, or Asian ancestry within the Black individual, it is usually wavy or straight in texture, and long. “Bad hair” is the extreme opposite of good hair—tightly coiled, thicker, and more likely to be short, clearly reflecting African ancestry (Robinson 2011). Further, Black females endure a host of negative effects due to the lack of available options to learn and care about natural afro hair which has created an enduring interlocking system of oppression for African American women that inhibits Black females from being free to express themselves and their beauty in a way that does not revolve around the Eurocentric standards. (White 2005). Racialized beauty standards combined with the color complex make hair texture and length an essential part of Black female identity (Randle 2015). Using an Afrocentric Black feminist perspective, I seek to understand how the Eurocentric standard of beauty negatively affects Black women’s positive self-identity and enhances their struggle to embrace their natural hair. This paper will explore the history of Black hair, Black hair politics, Black hair in the workplace, and discuss how Black females who choose to wear their hair natural is a form of empowerment while simultaneously challenging social norms

Two adaptation processes in auditory hair cells together can provide an active amplifier

The hair cells of the vertebrate inner ear convert mechanical stimuli to electrical signals. Two adaptation mechanisms are known to modify the ionic current flowing through the transduction channels of the hair bundles: a rapid process involves calcium ions binding to the channels; and a slower adaptation is associated with the movement of myosin motors. We present a mathematical model of the hair cell which demonstrates that the combination of these two mechanisms can produce `self-tuned critical oscillations', i.e. maintain the hair bundle at the threshold of an oscillatory instability. The characteristic frequency depends on the geometry of the bundle and on the calcium dynamics, but is independent of channel kinetics. Poised on the verge of vibrating, the hair bundle acts as an active amplifier. However, if the hair cell is sufficiently perturbed, other dynamical regimes can occur. These include slow relaxation oscillations which resemble the hair bundle motion observed in some experimental preparations.Comment: 13 pages, 6 figures,REVTeX 4, To appear in Biophysical Journa