Darlene Dixon | |
---|---|
Born | New Jersey, US |
Alma mater | Tuskegee University Michigan State University |
Scientific career | |
Fields | Toxicologic pathology, veterinary medicine |
Institutions | National Institute of Environmental Health Sciences |
Darlene Dixon is an American veterinary scientist and toxicologic pathologist researching the pathogenesis/carcinogenesis of tumors affecting the reproductive tract of rodents and humans and assessing the role of environmental and endogenous hormonal factors in the growth of these tumors. She is a senior investigator at the National Institute of Environmental Health Sciences.
Dixon was born in New Jersey. [1] She earned a B.S. at Tuskegee University where she completed a Doctor of Veterinary Medicine (D.V.M.) degree in 1982. Dixon earned a Ph.D. in 1985 at Michigan State University. She conducted a postdoctoral fellowship at The Rockefeller University, Laboratory Animal Research Center. Dixon received her board certification from the American College of Veterinary Pathologists (ACVP) in 1987. [2]
Dixon joined the National Institute of Environmental Health Sciences (NIEHS) in 1987. She works as a veterinary scientist and toxicologic pathologist. As of September 2019, she is a senior investigator in the NIEHS National Toxicology Program's Molecular Pathogenesis Group. [2] [1]
Dixon is active in the North Carolina Women of Color Research Network (NC WoCRN). She mentors as part of the NIEHS Scholars Connect Program (NSCP), which offers a year-long apprenticeship program to students from historically black colleges and universities, as well as other area academic institutions. [3]
Dixon’s group focuses on defining the pathogenesis/carcinogenesis of tumors affecting the reproductive tract of rodents and humans and assessing the role of environmental and endogenous hormonal factors in the growth of these tumors. [2]
The group has used cell lines, 3D cultures, archival mouse tissue, and human clinical samples to study the influence of membrane-associated estrogen receptors and growth factors/receptors and their signaling pathways on uterine leiomyoma (fibroid) growth. Group members use leiomyoma and patient-matched myometrial samples, clinical tissues taken from cycle-staged, premenopausal women participating in the NIEHS George Washington University Fibroid Study. The rodent tissue samples are either from in-house studies or National Toxicology Program archives. [2]
Dixon and her group seek to understand the basic molecular mechanisms of disease, which may lead to therapeutic interventions that generate alternative non-invasive treatments for clinical fibroids and other diseases affecting the female reproductive tract. [2]
The endometrium is the inner epithelial layer, along with its mucous membrane, of the mammalian uterus. It has a basal layer and a functional layer: the basal layer contains stem cells which regenerate the functional layer. The functional layer thickens and then is shed during menstruation in humans and some other mammals, including apes, Old World monkeys, some species of bat, the elephant shrew and the Cairo spiny mouse. In most other mammals, the endometrium is reabsorbed in the estrous cycle. During pregnancy, the glands and blood vessels in the endometrium further increase in size and number. Vascular spaces fuse and become interconnected, forming the placenta, which supplies oxygen and nutrition to the embryo and fetus. The speculated presence of an endometrial microbiota has been argued against.
Heavy menstrual bleeding (HMB), previously known as menorrhagia or hematomunia, is a menstrual period with excessively heavy flow. It is a type of abnormal uterine bleeding (AUB).
Methylcholanthrene is a highly carcinogenic polycyclic aromatic hydrocarbon produced by burning organic compounds at very high temperatures. Methylcholanthrene is also known as 3-methylcholanthrene, 20-methylcholanthrene or the IUPAC name 3-methyl-1,2-dyhydrobenzo[j]aceanthrylene. The short notation often used is 3-MC or MCA. This compound forms pale yellow solid crystals when crystallized from benzene and ether. It has a melting point around 180 °C and its boiling point is around 280 °C at a pressure of 80 mmHg. Methylcholanthrene is used in laboratory studies of chemical carcinogenesis. It is an alkylated derivative of benz[a]anthracene and has a similar UV spectrum. The most common isomer is 3-methylcholanthrene, although the methyl group can occur in other places.
Adenomyosis is a medical condition characterized by the growth of cells that proliferate on the inside of the uterus (endometrium) atypically located among the cells of the uterine wall (myometrium), as a result, thickening of the uterus occurs. As well as being misplaced in patients with this condition, endometrial tissue is completely functional. The tissue thickens, sheds and bleeds during every menstrual cycle.
Vaginal bleeding is any expulsion of blood from the vagina. This bleeding may originate from the uterus, vaginal wall, or cervix. Generally, it is either part of a normal menstrual cycle or is caused by hormonal or other problems of the reproductive system, such as abnormal uterine bleeding.
Uterine fibroids, also known as uterine leiomyomas or fibroids, are benign smooth muscle tumors of the uterus. Most women with fibroids have no symptoms while others may have painful or heavy periods. If large enough, they may push on the bladder, causing a frequent need to urinate. They may also cause pain during penetrative sex or lower back pain. A woman can have one uterine fibroid or many. Occasionally, fibroids may make it difficult to become pregnant, although this is uncommon.
Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism. Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens. Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens". Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins.
A myoma is a type of tumor that involves muscle cells. There are two main types of myoma:
A leiomyosarcoma, also known as LMS, is a rare malignant (cancerous) smooth muscle tumor. The origin of the word is from leio- + myo- + sarcoma which means malignant smooth muscle tumor. The stomach, bladder, uterus, blood vessels, and intestines are examples of hollow organs made up of smooth muscles where LMS can be located, however the uterus or abdomen are the most common sites.
A selective progesterone receptor modulator (SPRM) is an agent that acts on the progesterone receptor (PR), the biological target of progestogens like progesterone. A characteristic that distinguishes such substances from full receptor agonists and full antagonists is that their action differs in different tissues, i.e. agonist in some tissues while antagonist in others. This mixed profile of action leads to stimulation or inhibition in tissue-specific manner, which further raises the possibility of dissociating undesirable adverse effects from the development of synthetic PR-modulator drug candidates.
Adenomyoma is a tumor (-oma) including components derived from glands (adeno-) and muscle (-my-). It is a type of complex and mixed tumor, and several variants have been described in the medical literature. Uterine adenomyoma, the localized form of uterine adenomyosis, is a tumor composed of endometrial gland tissue and smooth muscle in the myometrium. Adenomyomas containing endometrial glands are also found outside of the uterus, most commonly on the uterine adnexa but can also develop at distant sites outside of the pelvis. Gallbladder adenomyoma, the localized form of adenomyomatosis, is a polypoid tumor in the gallbladder composed of hyperplastic mucosal epithelium and muscularis propria.
Secreted frizzled-related protein 1, also known as SFRP1, is a protein which in humans is encoded by the SFRP1 gene.
Genital leiomyomas are leiomyomas that originate in the dartos muscles, or smooth muscles, of the genitalia, areola, and nipple. They are a subtype of cutaneous leiomyomas that affect smooth muscle found in the scrotum, labia, or nipple. They are benign tumors, but may cause pain and discomfort to patients. Genital leiomyoma can be symptomatic or asymptomatic and is dependent on the type of leiomyoma. In most cases, pain in the affected area or region is most common. For vaginal leiomyoma, vaginal bleeding and pain may occur. Uterine leiomyoma may exhibit pain in the area as well as painful bowel movement and/or sexual intercourse. Nipple pain, enlargement, and tenderness can be a symptom of nipple-areolar leiomyomas. Genital leiomyomas can be caused by multiple factors, one can be genetic mutations that affect hormones such as estrogen and progesterone. Moreover, risk factors to the development of genital leiomyomas include age, race, and gender. Ultrasound and imaging procedures are used to diagnose genital leiomyomas, while surgically removing the tumor is the most common treatment of these diseases. Case studies for nipple areolar, scrotal, and uterine leiomyoma were used, since there were not enough secondary resources to provide more evidence.
Female genital disease is a disorder of the structure or function of the female reproductive system that has a known cause and a distinctive group of symptoms, signs, or anatomical changes. The female reproductive system consists of the ovaries, fallopian tubes, uterus, vagina, and vulva. Female genital diseases can be classified by affected location or by type of disease, such as malformation, inflammation, or infection.
Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) or Reed's syndrome is rare autosomal dominant disorder associated with benign smooth muscle tumors and an increased risk of renal cell carcinoma. It is characterised by multiple cutaneous leiomyomas and, in women, uterine leiomyomas. It predisposes for renal cell cancer, an association denominated hereditary leiomyomatosis and renal cell cancer, and it is also associated with increased risk of uterine leiomyosarcoma. The syndrome is caused by a mutation in the fumarate hydratase gene, which leads to an accumulation of fumarate. The inheritance pattern is autosomal dominant and screening can typically begin in childhood.
Toxicodynamics, termed pharmacodynamics in pharmacology, describes the dynamic interactions of a toxicant with a biological target and its biological effects. A biological target, also known as the site of action, can be binding proteins, ion channels, DNA, or a variety of other receptors. When a toxicant enters an organism, it can interact with these receptors and produce structural or functional alterations. The mechanism of action of the toxicant, as determined by a toxicant’s chemical properties, will determine what receptors are targeted and the overall toxic effect at the cellular level and organismal level.
Serdar Bulun is a gynecologist, with a special interest in the common gynecologic diseases, endometriosis and uterine fibroids.
Lauren Anne Wise is a Canadian-American epidemiologist and Professor in the Department of Epidemiology at Boston University School of Public Health.
Donna Day Baird is an American epidemiologist and evolutionary-population biologist. She is a senior investigator at the National Institute of Environmental Health Sciences. She is known for her research in reproductive health through NIEHS.
Cheryl Lyn Walker is an American molecular biologist.