Persius/hicric huggingface dataset:
Ankyrin repeat

# Overview
The ankyrin repeat is a 33-residue motif in proteins consisting of two alpha helices separated by loops, first discovered in signaling proteins in yeast Cdc10 and Drosophila Notch. Ankyrin repeats mediate protein-protein interactions and are among the most common structural motifs in known proteins. They appear in bacterial, archaeal, and eukaryotic proteins, but are far more common in eukaryotes. Most proteins that contain the motif have four to six repeats, although its namesake ankyrin contains 24 and the largest known number of repeats is 34, predicted in a protein expressed by Giardia lamblia.
The ankyrin-repeat sequence motif has been studied using multiple sequence alignment to determine which conserved amino acid residues are critical for folding and stability. The residues that appear on the wide lateral surface of ankyrin repeat structures are variable, often hydrophobic, and involved mainly in mediating protein-protein interactions. An artificial protein design based on a  consensus sequence derived from sequence alignment has been synthesized and found to fold stably, representing the first designed protein with multiple identical repeats. More extensive design strategies have used combinatorial sequences to "evolve" ankyrin-repeat motifs that specifically recognize particular protein targets, a technique that has been presented as a possible alternative to antibody design for applications requiring high-affinity binding.
Ankyrin-repeat proteins present an unusual problem in the study of protein folding, which has largely focused on globular proteins that form well-defined tertiary structure stabilized by long-range, nonlocal residue-residue contacts. Ankyrin repeats, by contrast, contain very few such contacts (that is, they have a low contact order). Most studies have found that ankyrin repeats fold in a two-state folding mechanism, suggesting a high degree of folding cooperativity despite the local inter-residue contacts and the evident need for successful folding with varying numbers of repeats. Some evidence, based on synthesis of truncated versions of natural repeat proteins and on the examination of phi values, suggests that the C-terminus forms the folding nucleation site.
Ankyrin-repeat proteins have been associated with a number of human diseases; most notably, the cell cycle inhibitor p16 is associated with cancer and the Notch protein is a key component of cell signaling pathways whose intracellular repeat domain is disrupted in mutations that give rise to the neurological disorder known as CADASIL. A specialized family of ankyrin proteins known as muscle ankyrin repeat proteins (MARPs) are involved with the repair and regeneration of muscle tissue following damage due to injury and stress.
Antidiarrhoeal

# Overview
An antidiarrhoeal drug is any medication which provides symptomatic relief for diarrhoea.

# Types
- Electrolyte solutions are used to replace lost fluids and salts in acute cases.
- Bulking agents like methylcellulose, guar gum or plant fibre (bran, sterculia, ispaghul, etc.) are used for diarrhoea in functional bowel disease and to control ileostomy output.
- Absorbents absorb toxic substances that cause infective diarrhoea, methylcellulose is an absorbent as well.
- Opiates slow intestinal transit, but Loperamide is most commonly used, since it doesn't have the usual narcotic side effects.
Antimetabolite

# Overview
An antimetabolite is a chemical with a similar structure to a substance (a metabolite) required for normal biochemical reactions, yet different enough to interfere with the normal functions of cells, including cell division.

# Function

## Cancer treatment
Antimetabolites can be used in cancer treatment, as they interfere with DNA production and therefore cell division and the growth of tumors. Because cancer cells spend more time dividing than other cells, inhibiting cell division harms tumor cells more than other cells.
Anti-metabolites masquerade as purine (azathioprine, mercaptopurine) or pyrimidine - which become the building blocks of DNA. They prevent these substances becoming incorporated in to DNA during the S phase (of the cell cycle), stopping normal development and division.
They also affect RNA synthesis. However, because thymidine is used in DNA but not in RNA (where uracil is used instead), inhibition of thymidine sythesis via thymidylate synthase selectively inhibits DNA synthesis over RNA synthesis.
Due to their efficiency, these drugs are the most widely used cytostatics.
In the ATC system, they are classified under L01B.

## Antibiotics
Antimetabolites may also be antibiotics, such as sulfanilamide drugs, which inhibit dihydrofolate synthesis in bacteria by competing with para-aminobenzoic acid.

# Types
Main representatives of these drugs are:

## Folic acid analogues
- Methotrexate, a folic acid analogue, prevents the formation of tetrahydrofolate, essential for purine and pyrimidine synthesis, by inhibiting dihydrofolate reductase. This leads to inhibited production of DNA, RNA and proteins (as tetrahydrofolate is also involved in the synthesis of amino acids serine and methionine).
- Error creating thumbnail: File missing
Folic acid
- Methotrexate
- Pemetrexed
- Raltitrexed

## Purine analogues
- Azathioprine is the main immunosuppressive cytotoxic substance. It is widely used in transplantations to control rejection reactions. It is nonenzymatically cleaved to 6-mercaptopurine that acts as a purine analogue and an inhibitor of DNA synthesis. By preventing the clonal expansion of lymphocytes in the induction phase of the immune response, it affects both the cell and the humoral immunity. It also successfully suppresses autoimmunity.
- Mercaptopurine
- Thioguanine is used to treat acute leukemias and induction of remissions in acute granulocytic leukemias
- Fludarabine inhibits function of multiple DNA polymerases, DNA primase, DNA ligase I and is S phase-specific (since these enzymes are highly active during DNA replication).
- Pentostatin and cladribine are adenosine analogs which are primarily used to treat Hairy cell leukemia.
- Purine
- Error creating thumbnail: File missing
Mercaptopurine
- Tioguanine
- Fludarabine

## Pyrimidine analogues
- 5-fluorouracil (5FU) which inhibits thymidylate synthase.
- Floxuridine (FUDR)
- Cytosine arabinoside
- Pyrimidine
- Fluorouracil
- Floxuridine
- Gemcitabine
Antineoplastic

# Overview
Antineoplastics (or "antitumor antibiotics", or "noncovalent DNA-binding drugs", or "cytotoxic antibiotics", see also neoplastics) are drugs that inhibit and combat the development of tumors.
In the Anatomical Therapeutic Chemical Classification System, they are classified under L01D.

# Health Effects/Occupational Exposure
The adverse health effects associated with antineoplastic agents (cancer chemotherapy drugs, cytotoxic drugs) in cancer patients and some non-cancer patients treated with these drugs are well documented. The very nature of antineoplastic agents make them harmful to healthy cells and tissues as well as the cancerous cells. For cancer patients with a life-threatening disease, there is certainly a great benefit to treatment with these agents. However, for the health care workers who are exposed to antineoplastic agents as part of their work practice, precautions should be taken to eliminate or reduce exposure as much as possible. Pharmacists who prepare these drugs or nurses who may prepare and/or administer them are the two occupational groups who have the highest potential exposure to antineoplastic agents. Additionally, physicians and operating room personnel may also be exposed through the treatment of patients. Hospital staff, such as shipping and receiving personnel, custodial workers, laundry workers and waste handlers, all have potential exposure to these drugs during the course of their work. The increased use of antineoplastic agents in veterinary oncology also puts these workers at risk for exposure to these drugs.

# Modes of action
Antineoplastics work by:
- Inhibiting topoisomerase II, thereby stopping DNA from being unwound, which is required for both DNA replication and RNA/protein synthesis.
- Generating free radicals.
They are products of various strains of the soil fungus Streptomyces.

# Examples
- actinomycin (L01DA01 (WHO)).
The most important immunosuppressant from this group is dactinomycin, which is used to in kidney transplantations.
- The most important immunosuppressant from this group is dactinomycin, which is used to in kidney transplantations.
- anthracyclines
doxorubicin (L01DB01 (WHO))
daunorubicin (L01DB02 (WHO))
epirubicin (L01DB03 (WHO)), which also inhibit topoisomerase II)
- doxorubicin (L01DB01 (WHO))
- daunorubicin (L01DB02 (WHO))
- epirubicin (L01DB03 (WHO)), which also inhibit topoisomerase II)
- other cytotoxic antibiotics
bleomycin (L01DC01 (WHO)). Bleomycin acts in unique way through oxidation of a DNA-bleomycin-Fe(II) complex and forming free radicals, which induce damage and chromosomal aberrations.
plicamycin (L01DC02 (WHO))
mitomycin (L01DC03 (WHO))
- bleomycin (L01DC01 (WHO)). Bleomycin acts in unique way through oxidation of a DNA-bleomycin-Fe(II) complex and forming free radicals, which induce damage and chromosomal aberrations.
- plicamycin (L01DC02 (WHO))
- mitomycin (L01DC03 (WHO))
Antiaggregants

# Prevention and treatment of arterial thrombosis
Treatment of established arterial thrombosis includes the use of Antiplatelet drugs and thrombolytic therapy.
Antiplatelet drugs
Alter the platelet activation at the site of vascular damage crucial to the development of arterial thrombosis.
Aspirin irreversibly inhibits the enzyme COX, resulting in reduced platelet production of TXA2 (thromboxane - powerful vasoconstrictor which lowers cyclic AMP and initiates the platelet release reaction).
Dipyridamole inhibits platelet phosphodiesterase, causing an increase in cyclic AMP with potentiation of the action of PGI2  opposes actions of TXA2
Clopidogrel affects the ADP-dependent activation of IIb/IIIa complex
Glycoprotein IIb/IIIa receptor antagonists block a receptor on the platelet for fibrinogen and von Willebrand factor. 3 classes:
-	Murine-human chimeric antibodies (e.g. abciximab)
-	Synthetic peptides (e.g. eptifibatide)
-	Synthetic non-peptides (e.g. tirofiban)
Epoprostenol is a prostacyclin which is used to inhibit platelet aggregation during renal dialysis (with or without heparin) and is also used in primary pulmonary hypertension.
Thrombolytic therapy
Used in myocardial infarction, cerebral infarction and occasionally in massive pulmonary embolism. The main risk is bleeding. Treatment should not be given to patients who have had recent bleeding, uncontrolled hypertension or a hemorrhagic stroke, or surgery or other invasive procedures within the previous 10 days.
Streptokinase forms a complex with plasminogen, resulting in a conformational change which activates other plasminogen molecules to form plasmin.
Plasminogen activators (PA)
Tissue-type plasminogen activators (alteplase, tenecteplase) are produced by recombinant technology.
Antiangiogenic
Antiangiogenic refers to a chemical or biological agent that inhibits or greatly reduces formation of new blood vessels (angiogenesis).
These agents are sometimes used to combat cancer by starving tumors of the blood needed to grow and spread.
The pharmaceutical thalidomide is such an antiangiogenic agent.
When pregnant women take an antiangiogenic agent, the developing fetus will not form blood vessels properly and thereby stop the proper development of fetal limbs and circulatory systems.  The results of the late 1950s and early 1960s when pregnant women were given the drug were children with tiny flippers for arms and legs.
Anticarcinogen

# Overview
An anticarcinogen is any chemical which reduces the occurrence of cancers, reduces the severity of cancers that do occur, or acts against cancers that do occur, based on evidence from in vitro studies, animal models, epidemiological studies and/or clinical studies.
Preventative anticarcinogens act by enhancing an organism's natural defenses against cancer, by deactivating carcinogens or by blocking the mechanisms by which carcinogens act (such as free radical damage to DNA).
Anticarcinoma agents participate in the selective destruction of cancer cells, or inhibit the growth and proliferation of cancer cells.
Interest in preventative anticarcinogens is motivated primarily by the principle that it is preferable to prevent disease where possible, and that positive actions can be effective as well as negative ones (such as reducing exposure to known carcinogens). Anticarcinoma agents that do not have significant negative side effects have a similar potential role, by reducing the seriousness of any cancers that do occur.

# Known anticarcinogens
There is epidemiological evidence that a diet rich in antioxidant vitamins and flavonoids is anticarcinogenic. Interest in many popular nutritional supplements, including essential antioxidant nutrients such as selenium compounds and hormones such as melatonin and DHEA, is partly motivated by evidence that these have significant anticarcinogenic effects in appropriate quantities.  The major psychoactive component in marijuana, tetrahydrocannabinol, has been shown to have anticarcinogenic activity.  The other major component of cannabis - cannabidiol, has also been shown to inhibit cancer cell growth, with low potency in non-cancer cells. Although the inhibitory mechanism is not yet fully understood, Ligresti et al suggest that "cannabidiol exerts its effects on these cells through a combination of mechanisms that include either direct or indirect activation of CB2 and TRPV1 receptors, and induction of oxidative stress, all contributing to induce apoptosis."
Exocrine gland
Exocrine glands are glands that secrete their products (enzymes) into ducts (duct glands). They are the counterparts to endocrine glands, which secrete their products (hormones) directly into the bloodstream (ductless glands).

# Examples
Typical exocrine glands include sweat glands, salivary glands, mammary glands, stomach, liver and the pancreas.

# Types
There are multiple ways of classifying exocrine glands:

## Structure
Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland.
- The duct portion may be branched (called compound) or unbranched (called simple).
- The glandular portion may be tubular, acinar, or may be a mix of the two (called tubuloacinar). If the glandular portion branches, then the gland is called a branched gland.

## Method of secretion
Exocrine glands are named apocrine gland, holocrine gland, or merocrine gland based on how their product is secreted.
- Apocrine glands - a portion of the plasma membrane buds off the cell, containing the secretion.  Apocrine gland is often used to refer to the apocrine sweat glands which use merocrine secretion.
- Holocrine glands - the entire cell disintegrates to secrete its substance.
- Merocrine glands - cells secrete their substances by exocytosis. Also called "eccrine."

## Product secreted
- Serous cells secrete proteins, often enzymes. Examples include chief cells and Paneth cells
- Mucous cells secrete mucus. Examples include Brunner's glands, esophageal glands, and pyloric glands
- Mixed glands secrete both protein and mucus. Examples include the salivary glands, although parotid gland is predominantly serous, and sublingual gland is predominantly mucous.

# List of exocrine glands
Glands typically may be referred to by two or more means, though some terms are rarely seen.  The names of the anatomists who first described them are often employed, as:
Apolipoprotein

# Overview
Apolipoproteins are lipid-binding proteins which are the constituents of the plasma lipoproteins, sub-microscopic spherical particles that transport dietary lipids through the bloodstream from the intestine to the liver, and endogenously synthesized lipids from the liver to tissues that can store them (adipocytes), metabolize them (muscle, heart, lung), or secrete them (breast).  The amphipathic detergent-like properties of apolipoproteins solubilize the hydrophobic lipid constituents of lipoproteins.  In addition, apolipoproteins also serve as enzyme co-factors, receptor ligands, and lipid transfer carriers that regulate the intravascular metabolism of lipoproteins and their ultimate tissue uptake.

# Structure

# Classification

## Notes
- ApoB-48 is exclusively found in chylomicrons.  It is derived from the apoB-100 gene and is reduced to 48% of the N-terminal component of B-100 by RNA editing, with no LDL receptor (LDLr) binding domain.
- ApoE is found broadly in HDL, IDL, LDL, VLDL, and chylomicrons and binds to LDLr with varying affinity dependent on the inherited apoE allele. Three different apoE isoforms exist in humans: apoE2 with lower affinity to LDLr, apoE3 with intermediate binding affinity, and apoE4 with higher affinity.
- Apo(a) is a distinguishing structural protein of lipoprotein(a).  It is covalently bound to apoB-100 and inhibits plasminogen activation.

# Metabolism
Apolipoprotein synthesis in the intestine is regulated principally by the fat content of the diet.
Apolipoprotein synthesis in the liver is controlled by a host of factors, including dietary composition, hormones (insulin, glucagon, thyroxin, estrogens, androgens), alcohol intake, and various drugs (statins, niacin,and fibric acids).
Apotemnophilia
Apotemnophilia is the erotic interest in being or looking like an amputee. It should not be confused with acrotomophilia, which is the erotic interest in people who are amputees.
When experienced very strongly, some people with apotemnophilia come to feel discontented with their bodies and want to actually remove an otherwise healthy limb, a condition called Body Integrity Identity Disorder.  Some apotemnophiles seek surgeons to perform an amputation or purposefully injure a limb in order to force emergency medical amputation.

# Research Studies
Among a convenience sample of 52 apotemnophiles recruited from internet groups, the great majority wanted a single leg removed, cut above the knee. There are parallels between apotemnophilia as a motivation for Body Integrity Identity Disorder and autogynephilia as a motivation for some cases of male-to-female Gender Identity Disorder.
Protic solvent
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: 
There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us  to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.

# Overview
In chemistry a protic solvent is a solvent that has a hydrogen atom bound to an oxygen as in a hydroxyl group or a nitrogen as in an amine group.  More generally, any molecular solvent which contains dissociable H+, such as hydrogen fluoride, is called a protic solvent.  The molecules of such solvents can donate an H+ (proton). Conversely, aprotic solvents cannot donate hydrogen.
Common characteristics of protic solvents:
- solvents display hydrogen bonding
- solvents have an acidic hydrogen (although they may be very weak acids)
- solvents are able to stabilize ions
cations by unshared free electron pairs
anions by hydrogen bonding
- cations by unshared free electron pairs
- anions by hydrogen bonding
Examples are water, methanol, ethanol, formic acid, hydrogen fluoride and ammonia.
Polar aprotic solvents are solvents that share ion dissolving power with protic solvents but lack an acidic hydrogen. These solvents generally have high dielectric constants and high polarity.
Examples are dimethyl sulfoxide, dimethylformamide, dioxane and hexamethylphosphorotriamide, tetrahydrofuran.
Polar protic solvents are favorable for SN1 reactions, while polar aprotic solvents are favorable for SN2 reactions. Apart from solvent effects, polar aprotic solvents may also be essential for reactions which use strong bases, such as reactions involving Grignard reagents or n-butyllithium. If a protic solvent were to be used, the reagent would be consumed by a side reaction with the solvent.
Arachnodactyly
Arachnodactyly, also known as spider fingers refers to abnormally long and slender fingers. Toes and feet are also usually affected.

# Differential Diagnosis of Diseases Associated with Arachnodactyly
In alphabetical order:  
- Achard Syndrome
- Homocystinuria
- Lutembacher's Syndrome
- Marfan's Syndrome
- MASS Syndrome (heritable disorder involving Mitral valve, Aorta, Skeleton, Skin)
- Spondylocostal Dysostosis
- Van der Hoeve's Syndrome

# Pathological Findings
Images courtesy of Professor Peter Anderson DVM PhD and published with permission  PEIR, University of Alabama at Birmingham, Department of Pathology
- Arachnodactyly: Gross, natural color, long fingers
- Arachnodactyly: Gross, both feet 50 yo f with aortic dissection and mitral valve prolapse extremities suggest Marfan's syndrome but no cystic aortic lesions
Artemisia afra
Artemisia afra is a common species of the genus Artemisia in Africa, with a wide distribution from  South Africa, to areas reaching to the North and East, as far north as Ethiopia. Artemisia afra is the only indigenous species in this genus.
Artemisia afra grows in clumps, with ridged, woody stems, reaching from 0.5 meters to 2 meters in height. The leaves are dark green, of soft texture, and similar in shape to fern leaves. The undersides of the leaves are a lighter green, and are covered with white bristles. Artemisia afra blossoms in late summer, producing abundant bracts of butter-colored flowers, each approximately 3 to 5 millimeters in diameter. Artemisia afra exudes a pungent, sweet smell when any part of the plant is bruised.

# Ethnobiology
Artemisia afra is a well-known medicinal plant in Africa, and is still used effectively by people of many cultures. Uses range from treating cough, fever, colic, headache, to intestinal parasites and malaria. In addition, Artemisia afra is frequently used as a moth repellent, and in organic insecticidal sprays.
The roots, stems and leaves are used as enemas, poultices, infusions, lotions, inhaled (e.g. smoked or snuffed), or as an essential oil.

# Essential oil
Essential oil extracts of Artemisia afra are prepared by steam distillation using twigs and blossoms. Extracts contain the following components (via gas chromatography) which are typical of extracts of the Artemisia genus:
- -thujone 52.9%
- -thujone 15.07%
- 1,8 cineole 10.66%
- camphor 5.72%
- germacrene 1.60%
- -cadinene 1.16%
- -terpineol 0.96%
- e-chrysanthenyl acetate 0.78%
- camphene 0.71%
- -pinene 0.51%
- -pinene 0.46%
- trans--ocimene 0.45%
- myrcene 0.22%
Arterial bruit
Synonyms and keywords: arterial murmur

# Overview
Arterial bruits is the term for the unusual swishing sound that blood makes when it rushes past an obstruction (called turbulent flow) in an artery when the sound is auscultated with the bell portion of a stethoscope.

# Causes

## Life Threatening Causes
Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.
There are no known life threatening causes of arterial bruit that would result in death or permanent disability if not treated within 24 hours.

## Common Causes
- Aortic coarctation
- Arterial aneurysm
- Arteriosclerosis
- Arteriosclerotic plaque
- Arteriovenous fistula
- Carotid artery stenosis
- Carotid atherosclerosis
- Carotid-cavernous fistula
- Peripheral vascular disease

## Causes by Organ System

## Causes in Alphabetical Order