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Designing for Upper Torso and Arm Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
This chapter begins with internal anatomy and goes on to describe external features pertinent to wearable product design. The upper torso contains key components of many body systems. The vital circulatory and respiratory organs are centrally located. The torso houses skeletal elements, including the bony connections of the arms to the rib cage, and muscles that provide postural support and motion. Male and female torsos demonstrate secondary sexual characteristics with variations in skeletal structure, muscle bulk, fat patterning, and breast formation. Important superficial structures, skin and body hair, encase and protect the body. The natural motion of the upper body, total spine, and arms complicates the design process for this body segment. Methods of landmarking, measuring, and fitting the upper torso and arms need to take motion into consideration.
Toxicity and Toxins
Published in Gary S. Moore, Kathleen A. Bell, Living with the Earth, 2018
Gary S. Moore, Kathleen A. Bell
Hormones are a type of chemical messenger. They are made in the body’s organs, glands, or tissues and conveyed through the blood to a target organ or tissue, where the hormone stimulates its target to increase or decrease functional activity or secretions. Hormones are active in very small quantities and minor disturbances of their concentrations in the body can disrupt normal functioning. They are critical in the regulation of many life processes, including sexual development, metabolic functions, brain development, human growth, and the fight-or-flight stress response. As examples, androgens regulate the development and maintenance of male sexual characteristics, while estrogens stimulate the development of female sexual characteristics. The predominant and most active androgen is testosterone, which is produced by the male testes. The other androgens that support the functions of testosterone are produced mainly by the adrenal cortex—the outer substance of the adrenal glands. Estrogen is produced primarily in the ovaries, with some minor production in the liver and breasts.
Halogenated Hydrocarbons: Persistence, Toxicity, and Problems
Published in Richard J. Sundberg, The Chemical Century, 2017
Studies relating DDT and DDE exposure to adverse health effects in humans are difficult. Essentially universal background exposure means there is no “control group.” Retrospective epidemiological studies are sometimes contradictory and are often limited by lack of precise knowledge of the time and extent of exposure. There have been several studies suggesting an association of fetal death with high levels of chlorinated pesticides, but in all cases the level of evidence is considered “limited.”18 The US EPA and IARC have classified PCBs as probable human carcinogens. Laboratory studies have demonstrated that both DDT and DDE are bound at estrogen receptors. They are thus classified as endocrine disruptors. The development of sexual characteristics is under the control of estrogen receptors that regulate transcription of genes. It is noteworthy that not all species determine sex at fertilization, as is the case with mammals and birds. Many species of fish and amphibians can undergo sex conversion under the influence of hormonal agents. Several cases of extreme exposure to chlorinated pesticides as a result of accidental spills have led to reproductive abnormalities in fish and amphibians. Figure 4.2 summarizes the possible mechanism of action.
Genotoxicity of quinone: An insight on DNA adducts and its LC-MS-based detection
Published in Critical Reviews in Environmental Science and Technology, 2022
Yue Xiong, Han Yeong Kaw, Lizhong Zhu, Wei Wang
Estrogens are important female hormones that promote the development of secondary sexual characteristics and the maturation of sexual organs. However, excessive exposure to estrogens either in abnormal menstrual period or drug therapy can increase the risk of cancer in hormone-sensitive tissues, including breast, ovarian and endometrial cancers (Bolton & Thatcher, 2008). Estrogens can be categorized into endogenous estrogens such as estrone (E1) and 17-β estradiol (E2), and exogenous estrogens like equilin and equilenin that exhibit similar properties to endogenous estrogens, which are common components of a hormone replacement therapy medication named Premarin. E1, E2 and equilenin shared identical metabolic pathway. Generally, they were oxidized to catechol estrogens (3,4-OHE1/E2, 2,3-OHE1/E2, 3,4-OHEH) by cytochromes P450, then underwent further oxidation to corresponding estrogen o-quinones under the functions of Cu+, Fe2+ ions, oxidative enzymes or molecular oxygen (Figure S1) (Stack, 2015). Imbalanced metabolism of estrogen yielded excessive catechol estrogen quinones with high eletrophilicity and redox-activity, thus increasing the formation of estrogen-DNA adducts and eventually cause DNA damage (Penning, 2017).
Evaluation of environmental effects of heavy metals on biochemical profile and oxidative stress among children at brick kiln sites
Published in Archives of Environmental & Occupational Health, 2021
Mehwish David, Naheed Turi, Qurat-ul Ain, Humaira Rahman, Sarwat Jahan
The GH has essential role in determining puberty, gametogenesis and fertility of an individual.13 It is responsible for determining the secondary sexual characteristics at pubertal development.44 In the present study, the level of growth hormone was significantly decreased in exposed group in comparison with the control group. Decrease in GH may affect the reproductive potential of brick kiln workers by inducing precocious/delayed puberty. As puberty is determined by the interplay of adrenarche and pubarche, the increased levels of stress hormone (cortisol) might act along with decreased GH levels and may affect appearance of secondary sexual characters and puberty. Steroids act at the pituitary and hypothalamic levels and therefore, modulate the production of growth hormone and support the sex related patterns of pulsatile GH secretions.45,46
Investigation of associations between exposures to pesticides and testosterone levels in Thai farmers
Published in Archives of Environmental & Occupational Health, 2018
Parinya Panuwet, Chandresh Ladva, Dana Boyd Barr, Tippawan Prapamontol, John D. Meeker, Priya Esilda D'Souza, Héctor Maldonado, P. Barry Ryan, Mark G. Robson
Previously, in a biomonitoring study, we reported that male Thai farmers from different communities were exposed to several classes of pesticides.4,5 Some of these pesticides were reported to be associated with levels of testosterone.1–3,5,7–9,13 Therefore, we conducted a cross-sectional study to look into dose-response relationships between exposures to these pesticides (as measured by levels of urinary pesticide metabolites) and levels of total and free testosterone in archived serum samples. Levels of total testosterone in males indicate the production capacity or efficiency of Leydig cells. Levels of free testosterone, the biologically active fraction of the hormone, contribute to the development of sexual characteristics.26,27 Alterations of total testosterone levels may indicate malfunction of the Leydig cells or inhibition of the enzymes responsible for testosterone production. Changes in free testosterone levels may lead to outcomes related to male sexual characteristics.