Pregnane X Receptor
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Pregnane X Receptor
In the field of molecular biology, the pregnane X receptor (PXR), also known as the steroid and xenobiotic sensing nuclear receptor (SXR) or nuclear receptor subfamily 1, group I, member 2 (NR1I2) is a protein that in humans is encoded by the ''NR1I2'' (nuclear Receptor subfamily 1, group I, member 2) gene. Function PXR is a nuclear receptor whose primary function is to sense the presence of foreign toxic substances and in response up regulate the expression of proteins involved in the detoxification and clearance of these substances from the body. PXR belongs to the nuclear receptor superfamily, members of which are transcription factors characterized by a ligand-binding domain and a DNA-binding domain. PXR is a transcriptional regulator of the cytochrome P450 gene CYP3A4, binding to the response element of the CYP3A4 promoter as a heterodimer with the 9-cis retinoic acid receptor RXR. It is activated by a range of compounds that induce CYP3A4, including dexamethasone and ...
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Molecular Biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physical structure of biological macromolecules is known as molecular biology. Molecular biology was first described as an approach focused on the underpinnings of biological phenomena - uncovering the structures of biological molecules as well as their interactions, and how these interactions explain observations of classical biology. In 1945 the term molecular biology was used by physicist William Astbury. In 1953 Francis Crick, James Watson, Rosalind Franklin, and colleagues, working at Medical Research Council unit, Cavendish laboratory, Cambridge (now the MRC Laboratory of Molecular Biology), made a double helix model of DNA which changed the entire research scenario. They proposed the DNA structure based on previous research done by Ro ...
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5α-dihydroprogesterone
5α-Dihydroprogesterone (5α-DHP, allopregnanedione, or 5α-pregnane-3,20-dione) is an endogenous progestogen and neurosteroid that is synthesized from progesterone. It is also an intermediate in the synthesis of allopregnanolone and isopregnanolone from progesterone. 5α-DHP is metabolized by the aldo-keto reductases (AKRs) AKR1C1, AKR1C2, and AKR1C4 with high catalytic efficiency. AKR1C1 preferentially forms 20α-hydroxy-5α-pregnane-3-one while AKR1C2 preferentially forms allopregnanolone. Similarly AKR1C1 reduces and consequently inactivates allopregnanolone into 5α-pregnane-3α,20α-diol. In contrast to the other AKRs, AKR1C3 has low catalytic efficiency for reduction of 5α-DHP. These AKRs are highly expressed in the human liver and mammary gland but have relatively modest expression in the human brain and uterus. 5α-DHP is an agonist of the progesterone receptor and a positive allosteric modulator of the GABAA receptor (albeit with an affinity for this receptor ...
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Paclitaxel
Paclitaxel (PTX), sold under the brand name Taxol among others, is a chemotherapy medication used to treat a number of types of cancer. This includes ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical cancer, and pancreatic cancer. It is administered by intravenous injection. There is also an albumin-bound formulation. Common side effects include hair loss, bone marrow suppression, numbness, allergic reactions, muscle pains, and diarrhea. Other serious side effects include heart problems, increased risk of infection, and lung inflammation. There are concerns that use during pregnancy may cause birth defects. Paclitaxel is in the taxane family of medications. It works by interference with the normal function of microtubules during cell division. Paclitaxel was first isolated in 1971 from the Pacific yew and approved for medical use in 1993. It is on the World Health Organization's List of Essential Medicines. It has been made from precu ...
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Meclizine
Meclizine, sold under the brand name Bonine, among others, is an antihistamine used to treat motion sickness and dizziness (vertigo). It is taken by mouth. Effects generally begin in an hour and last for up to a day. Common side effects include sleepiness and dry mouth. Serious side effects may include allergic reactions. Use in pregnancy appears safe, but has not been well studied while use in breastfeeding is of unclear safety. It is believed to work in part by anticholinergic and antihistamine mechanisms. Meclizine was patented in 1951 and came into medical use in 1953. It is available as a generic medication and often over the counter. In 2020, it was the 142nd most commonly prescribed medication in the United States, with more than 4million prescriptions. Medical uses Meclizine is used to treat symptoms of motion sickness. Safety and efficacy in children younger than twelve years of age has not been established; therefore, use in this population is not recommended. Mec ...
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Hyperforin
Hyperforin is a phytochemical produced by some of the members of the plant genus ''Hypericum'', notably ''Hypericum perforatum'' (St John's wort). Hyperforin may be involved in the pharmacological effects of St. John's wort, specifically in its antidepressant effects. Occurrence Hyperforin has only been found in significant amounts in ''Hypericum perforatum'' with other related species such as '' Hypericum calycinum'' containing lower levels of the phytochemical. It accumulates in oil glands, pistils, and fruits, probably as a plant defensive compound. The first natural extractions were done with ethanol and afforded a 7:1 yield of crude extract to phytochemical however, this technique produced a mixture of hyperforin and adhyperforin. The extraction technique has since been modernized using lipophilic liquid CO2 extraction to afford a 3:1 crude to phytochemical extraction which is then further purified away from adhyperforin. This CO2 extraction is rather tricky still because t ...
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Bile Acid
Bile acids are steroid acids found predominantly in the bile of mammals and other vertebrates. Diverse bile acids are synthesized in the liver. Bile acids are conjugated with taurine or glycine residues to give anions called bile salts. Primary bile acids are those synthesized by the liver. Secondary bile acids result from bacterial actions in the colon (anatomy), colon. In humans, taurocholic acid and glycocholic acid (derivatives of cholic acid) and taurochenodeoxycholic acid and glycochenodeoxycholic acid (derivatives of chenodeoxycholic acid) are the major bile salts. They are roughly equal in concentration. The salts of their 7-alpha-dehydroxylated derivatives, deoxycholic acid and lithocholic acid, are also found, with derivatives of cholic, chenodeoxycholic and deoxycholic acids accounting for over 90% of human biliary bile acids. Bile acids comprise about 80% of the organic compounds in bile (others are phospholipids and cholesterol). An increased secretion of bile acids ...
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Antimycotic
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cryptococcal meningitis, and others. Such drugs are usually yes obtained by a doctor's prescription, but a few are available over the counter (OTC). Types of antifungal There are two types of antifungals: local and systemic. Local antifungals are usually administered topically or vaginally, depending on the condition being treated. Systemic antifungals are administered orally or intravenously. Of the clinically employed azole antifungals, only a handful are used systemically. These include ketoconazole, itraconazole, fluconazole, fosfluconazole, voriconazole, posaconazole, and isavuconazole. Examples of non-azole systemic antifungals include griseofulvin and terbinafine. Classes Polyenes A polyene is a molecule with multiple conjugated dou ...
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Rifaximin
Rifaximin, is a non-absorbable, broad spectrum antibiotic mainly used to treat travelers' diarrhea. It is based on the rifamycin antibiotics family. Since its approval in Italy in 1987, it has been licensed in over more than 30 countries for the treatment of a variety of gastrointestinal diseases like irritable bowel syndrome, and hepatic encephalopathy. It acts by inhibiting RNA synthesis in susceptible bacteria by binding to the RNA polymerase enzyme. This binding blocks translocation, which stops transcription. It is marketed under the brand name Xifaxan by Salix Pharmaceuticals. Medical uses Travelers’ Diarrhea (TD) Rifaximin is used to treat traveler's diarrhea caused by certain bacteria (E. coli) in adults and children at least 12 years of age. It treats traveler's diarrhea by stopping the growth of the bacteria that cause diarrhea. Rifaximin will not work to treat traveler's diarrhea that is bloody or occurs with fever. Irritable Bowel Syndrome (IBS) Rifaximin is ...
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Antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of such infections. They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the common cold or influenza; drugs which inhibit viruses are termed antiviral drugs or antivirals rather than antibiotics. Sometimes, the term ''antibiotic''—literally "opposing life", from the Greek roots ἀντι ''anti'', "against" and βίος ''bios'', "life"—is broadly used to refer to any substance used against microbes, but in the usual medical usage, antibiotics (such as penicillin) are those produced naturally (by one microorganism fighting another), whereas non-antibiotic antibacterials (such as sulfonamides and antiseptics) ...
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Mifepristone
Mifepristone, also known as RU-486, is a medication typically used in combination with misoprostol to bring about a medical abortion during pregnancy and manage early miscarriage. This combination is 97% effective during the first 63 days of pregnancy. It is also effective in the second trimester of pregnancy. Effectiveness should be verified two weeks after use. It is taken by mouth. Common side effects include abdominal pain, feeling tired, and vaginal bleeding. Serious side effects may include heavy vaginal bleeding, bacterial infection, and birth defects if the pregnancy does not end. If used, appropriate follow up care needs to be available. Mifepristone is an antiprogestogen. It works by blocking the effects of progesterone, making both the cervix and uterine vessels dilate and causing uterine contraction. Mifepristone was developed in 1980 and came into use in France in 1987. It became available in the United States in 2000. It is on the WHO Model List of Essential Me ...
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Spironolactone
Spironolactone, sold under the brand name Aldactone among others, is a medication that is primarily used to treat fluid build-up due to heart failure, liver scarring, or kidney disease. It is also used in the treatment of high blood pressure, low blood potassium that does not improve with supplementation, early puberty in boys, acne and excessive hair growth in women, and as a part of transgender hormone therapy in transfeminine people. Spironolactone is taken by mouth. Common side effects include electrolyte abnormalities, particularly high blood potassium, nausea, vomiting, headache, rashes, and a decreased desire for sex. In those with liver or kidney problems, extra care should be taken. Spironolactone has not been well studied in pregnancy and should not be used to treat high blood pressure of pregnancy. It is a steroid that blocks the effects of the hormones aldosterone and testosterone and has some estrogen-like effects. Spironolactone belongs to a class of medicati ...
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Cyproterone Acetate
Cyproterone acetate (CPA), sold alone under the brand name Androcur or Ethinylestradiol/cyproterone acetate, with ethinylestradiol under the brand names Diane or Diane-35 among others, is an antiandrogen and progestin medication used in the treatment of androgen-dependent conditions such as acne, hirsutism, excessive body hair growth, precocious puberty, early puberty, and prostate cancer, as a component of feminizing hormone therapy for transgender women, and in oral contraceptive, birth control pills. It is formulated and used both alone and in combination with an estrogen (medication), estrogen. CPA is taken Oral administration, by mouth one to three times per day. Common side effects of high-dose CPA in men include gynecomastia (breast development) and feminization (biology), feminization. In both men and women, possible side effects of CPA include hypogonadism, low sex hormone levels, reversible infertility, sexual dysfunction, fatigue (medical), fatigue, depression (mood), ...
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