Persius/hicric huggingface dataset:
Foramen ovale (heart)
Assistant Editor-In-Chief: Kristin Feeney, B.S. ]

# Overview
In the fetal heart, the foramen ovale (or ostium secundum of Born) allows blood to enter the left atrium from the right atrium. It is one of two shunts, the other being the ductus arteriosus, that allows blood entering the right atrium to bypass the pulmonary circulation. Another similar adaptation in the fetus is the ductus venosus. In most individuals, the foramen ovale closes within the first year after birth to form the fossa ovalis.

# Development
The foramen ovale begins forming late in the fourth week of gestation. Initially the atria are separated from one another by the septum primum except for a small opening in the septum, the ostium primum. As the septum primum grows, the ostium primum narrows and eventually closes. Before it does so, bloodflow from the inferior vena cava wears down a portion of the septum primum, forming the ostium secundum. Some embryologists postulate that the ostium secundum may be formed through programmed cell death. The ostium secundum provides communication between the atria after the ostium primum closes completely. Subsequently, a second wall of tissue, the septum secundum, grows over the ostium secundum in the right atrium. Bloodflow then only passes from the right to left atrium by way of a small passageway in the septum secundum and then through the ostium secundum. This passageway is called the foramen ovale.

# Closure
Normally this opening closes in the first year of life. When the lungs become functional at birth, the pulmonary pressure decreases and the left atrial pressure exceeds that of the right. This forces the septum primum against the septum secundum, functionally closing the foramen ovale. In time the septa eventually fuse, leaving a remnant of the foramen ovale, the fossa ovalis.

# Clinical Relevance

## Patent foramen ovale
In about 30% of adults the foramen ovale does not close completely, but remains as a small patent foramen ovale. People with a patent foramen ovale are more likely to suffer from migraine headaches. Corrective surgery often results in the complete cessation of migraines in some patients, and a greater than 50% reduction in migraines on average .

# Anatomy
- Sketch showing foramen ovale in a fetal heart. Red arrow shows blood from the inferior caval vein. HV: right atrium, VF: left atrium. HH og VH: right and left ventricle. The heart still has a common pulmonary vein (LV), in stead of four.
- Heart of human embryo of about thirty-five days, opened on right side.
Formaldehyde releaser

# Overview
A formaldehyde releaser is a chemical compound that slowly releases formaldehyde.

# Antimicrobials
Formaldehyde releasers are often used an antimicrobial preservative in cosmetics. Examples include:
- Quaternium-15
- Imidazolidinyl urea (Germall 115)
- Diazolidinyl urea (Germall II)
- DMDM hydantoin (Glydant)
- 2-Bromo-2-nitropropane-1,3-diol (Bronopol) (formaldehyde release is not related to mechanism of action)
- Tris(hydroxymethyl) nitromethane (Tris Nitro)
- Hydroxymethylglycinate (Suttocide A)

# Resins and plastics
- Polyoxymethylene plastic (Delrin)
- Phenol formaldehyde resin
- Urea formaldehyde resin
- Melamine resin

# Others
- Paraformaldehyde
Formate dehydrogenase

# Overview
Formate dehydrogenases are a set of enzymes that catalyse the oxidation of formate to bicarbonate, donating the electrons to a second substrate, such as NAD+ in formate:NAD+ oxidoreductase (EC 1.2.1.2) or to a cytochrome in formate:ferricytochrome-b1 oxidoreductase (EC 1.2.2.1).
NAD-dependent formate dehydrogenases are important in methylotrophic yeast and bacteria and are vital in the catabolism of C1 compounds such as methanol. The cytochrome-dependent enzymes are more important in anaerobic metabolism in prokaryotes. For example, in E. coli, the formate:ferricytochrome-b1 oxidoreductase is an intrinsic membrane protein with two subunits and is involved in anaerobic nitrate respiration.
NAD-dependent reaction
Formate + NAD(+)  CO(2) + NADH
Cytochrome-dependent reaction
Formate + 2 ferricytochrome b1  CO(2) + 2 ferrocytochrome b1 + 2 H(+)
Free radical addition
Free radical addition is an addition reaction in organic chemistry involving free radicals .
The basic steps with examples of the free radical addition (also known as radical chain mechanism) are:
- Initiation by a radical initiator
- Chain propagation
- Chain termination
Free radical addition depends on a reagent having a (relatively) weak bond, allowing it to homolyse to form radicals (often with heat or light). Reagents without such a weak bond would likely proceed via a different mechanism. An example of an addition reaction involving aryl radicals is the Meerwein arylation.

# Addition of mineral acid to an alkene
To illustrate, consider the alkoxy radical-catalyzed, anti-Markovnikov reaction of hydrogen bromide to an alkene.  In this reaction, a catalytic amount of organic peroxide is needed to abstract the acidic proton from HBr and generate the bromine radical, however a full molar equivalent of alkene and acid is required for completion.
File:Peroxide Free-radical-addition.png
Note that the radical will be on the more substituted carbon. Free radical addition does not occur with the molecules HCl or HI. Both reactions are extremely endothermic and are not chemically favored.

# Self-terminating oxidative radical cyclizations
In one specific type of radical addition called self-terminating oxidative radical cyclization, alkynes are oxidized to ketones with intramolecular ring closure and the radical species are inorganic rather than carbon based. This type of reaction is self-terminating because propagating is not possible and the initiator is used in stoichiometric amounts. .
As an example a nitrate radical is generated by photolysis of CAN which reacts with an alkyne to generate first a very reactive vinyl radical and then via a 1,5-hydrogen atom transfer (HAT) and 5-exo-trig ring-closure a ketyl radical. The ketyl dislodges a nitrite radical which is not reactive enough for propagation and the ketone is formed.
The radical species in effect is a single oxygen atom synthon. Other inorganic radical that show this type of reactivity are sulfate radical ions (from ammonium persulfate) and hydroxyl radicals.
Free radical reaction

# Overview
A free radical reaction is any chemical reaction involving free radicals. This reaction type is abundant in organic reactions.
Two pioneering studies into free radical reactions have been the discovery of the triphenylmethyl radical by Moses Gomberg (1900) and the lead-mirror experiment  described by Friedrich Paneth in 1927. In this last experiment tetramethyllead is decomposed at elevated temperatures to methyl radicals and elemental lead in a quartz tube. The gaseous methyl radicals are moved to another part of the chamber in a carrier gas where they react with lead in a mirror film which slowly disappears.
When radical reactions are part of organic synthesis the radicals are often generated from radical initiators such as peroxides or azobis compounds. Many radical reactions are chain reactions with a chain initiation step, a chain propagation step and a chain termination step. Reaction inhibitors slow down a radical reaction. Radical reactions occur frequently in the gas phase, are often initiated by light, are rarely acid or base catalyzed an are not dependent on polarity of the reaction medium . Reactions are also similar whether in the gas phase or solution phase .

# Kinetics
The chemical kinetics of a radical reaction depend on all these individual reactions. In steady state the concentrations of initiating (I.) and terminating species T. are negligent and rate of initiation and rate of termination are equal. The overall reaction rate can be written as :
with a broken-order dependence of 1.5 with respect to the initiating species.
The reactivity of different compounds toward a certain radical is measured in so-called competition experiments. Compounds bearing carbon-hydrogen bonds react with radicals in the order primary  tertiary < benzyl < allyl reflecting the order in C-H bond dissociation energy 
Many stabilizing effects can be explained as resonance effects, an effect specific to radicals is the captodative effect.

# Reactions
The most important reaction types involving free radicals are:
- Free radical substitution, for instance free radical halogenation and autoxidation.
- Free radical addition reactions
- Intramolecular free radical reactions (substitution or addition) such as the Hofmann-Loffler reaction or the Barton reaction
- Free radical rearrangement reactions are rare compared to rearrangements involving carbocations and restricted to aryl migrations.
- Fragmentation reactions or homolysis, for instance the Norrish reaction, the Hunsdiecker reaction and certain decarboxylations. For fragmentations taking place in mass spectroscopy see mass spectrum analysis.
- Electron transfer. An example is the decomposition of certain peresters by Cu(I) which is a one-electron reduction reaction forming Cu(II), an alkoxy oxygen radical and a carboxylate. Another example is Kolbe electrolysis.
- Radical-nucleophilic aromatic substitution is a special case of nucleophilic aromatic substitution.
Specific reactions involving free radicals are combustion, pyrolysis and cracking
French catheter scale
Synonyms and keywords: Ch, F, Fr, FR

# Overview
The French catheter scale (most correctly abbreviated as Fr, but also often abbreviated as FR or F) is commonly used to measure the outer circumference of cylindrical medical instruments including catheters.  In the French Gauge system as it is also known, the diameter in millimeters of the catheter can be determined by dividing the French size by 3, thus an increasing French size corresponds with a larger diameter catheter.  The following equations summarize the relationships:
D(mm) = Fr/3
-r
Fr = D(mm)*3
For example, if the French size is 9, the diameter is  3 mm.
Note: the French scale is equal to the diameter in mm multiplied by three, not the circumference (diameter times ) as is sometimes thought.
This is contrary to needle-gauge size, where the diameter is 1/gauge inches; thus the larger the gauge needle, the more narrow the bore of the needle.
The Stubs Iron Wire Gauge system is also commonly used in a medical setting and is in fact more common for measuring needles, even though many find the Stubs system to be more confusing because the scale is non-linear and inversely proportional.

# Size Correspondence
1 Fr is equivalent to 0.33 mm = .013" = 1/77" of diameter. Thus the size in French units is roughly equal to the circumference of the catheter in millimeters.

# Historical Perspective
The French Gauge was devised by Joseph-Frederic-Benoit Charriere, a 19th century Parisian maker of surgical instruments, who defined the "diameter times 3" relationship.
In some countries (especially French speaking), this unit is called Charriere and abbreviated as Ch.
Fructosamine-3-kinase
Fructosamine-3-kinase is an enzyme that in humans is encoded by the FN3K gene.

# Function
FN3K catalyzes phosphorylation of fructosamines formed by glycation, the nonenzymatic reaction of glucose with primary amines followed by Amadori rearrangement. Phosphorylation of fructosamines may initiate metabolism of the modified amine and result in deglycation of glycated proteins.
FN3K is responsible for the formation of fructose 3-phosphate (F3P), a compound identified in the lenses of diabetic rats. The spontaneous decomposition of F3P leads to the formation of 3-deoxyglucosone (3DG). 3DG contributes to diabetic complications. Treatment of normal and diabetic rats with an inhibitor of FN3K demonstrated a large reduction (~50%) in systemic 3DG in both groups. Removal of 3DG at its source by inhibition of FN3K is a viable option to treat diabetes related diseases since it would require a much smaller dose of drug.
Nissen fundoplication

# Overview
Nissen fundoplication is a surgical procedure to treat gastroesophageal reflux disease (GERD) and hiatus hernia. In GERD it is usually performed when medical therapy has failed, but with paraesophageal hiatus hernia, it is the first-line procedure. Partial fundoplications known as a Dor fundoplication or Toupet fundoplication may accompany surgery for achalasia.

# The procedure
In a fundoplication, the gastric fundus (upper part) of the stomach is wrapped, or plicated, around the inferior part of the esophagus, restoring the function of the lower esophageal sphincter.  This prevents the reflux of gastric acid (in GERD) and/or the sliding of the fundus through the enlarged esophageal hiatus in the diaphragm. In a Nissen fundoplication, also called a complete fundoplication, the fundus is wrapped all the way around the esophagus.
Surgery for achalasia is generally accompanied by either a Dor or Toupet partial fundoplication.  In a Dor (anterior) fundoplication, the fundus is laid over the top of the esophagus.  In a Toupet (posterior) fundoplication, the fundus is wrapped around the back of the esophagus.
The procedure is often done laparoscopically.
When used as a method to alleviate gastroesophageal reflux symptoms in patients with delayed gastric empyting, this procedure is frequently done in conjunction with modification of the pylorus via pyloromyotomy or pyloroplasty.
Nissen fundoplication is generally considered to be safe and effective, with a mortality rate of less than 1%.  Studies have shown that after 10 years, 89.5% of patients are still symptom-free.

# Complications
Complications include "gas bloat syndrome", dysphagia (trouble swallowing), dumping syndrome, excessive scarring, and rarely, achalasia. The procedure can also become undone over time in about 5-10% of cases, leading to recurrence of the symptoms. If the symptoms warrant repeated surgery, the surgeon may use Marlex or another form of artificial mesh to strengthen the connection.
In "gas bloat syndrome", patients report being unable to belch, leading to an accumulation of gas in the stomach or small intestine. This is said to occur in 2-5% of patients, depending on surgical technique, and is commonly believed to be related to the tightness of the "wrap". Most often, gas bloat syndrome is self-limiting within 2 to 4 weeks, but in some it may persist. The offending gas may come from dietary sources (especially carbonated beverages). Another suspected cause is subconscious swallowing of air (aerophagia). If gas bloat syndrome occurs post operatively and does not resolve with time, dietary restrictions, or counselling regarding aerophagia, it may be beneficial to consider treating the condition with an endoscopic balloon dilitation.

# History
Dr. Rudolph Nissen first performed the procedure in 1955, and published the results of two cases in a 1956 Swiss Medical Weekly. In 1961 he published a more detailed overview of the procedure.  Nissen originally called the surgery gastroplication, but the procedure has borne his name since it gained popularity in the 1970's.
Glycoprotein IIb/IIIa
In medicine, glycoprotein IIb/IIIa (GPIIb/IIIa, also known as integrin IIb3) is an integrin complex found on platelets. It is a receptor for fibrinogen and von Willebrand factor and aids platelet activation. The complex is formed via calcium-dependent association of gpIIb and gpIIIa, a required step in normal platelet aggregation and endothelial adherence. Platelet activation by ADP (blocked by clopidogrel) leads to the aforementioned conformational change in platelet gpIIb/IIIa receptors that induces binding to fibrinogen. The gpIIb/IIIa receptor is a target of several drugs including abciximab, eptifibatide, and tirofiban.

# gpIIb/IIIa complex formation
Once platelets are activated, granules secrete clotting mediators, including both ADP and TXA2. These then bind their respective receptors on platelet surfaces, in both an autocrine and paracrine fashion (binds both itself and other platelets). The binding of these receptors result in a cascade of events resulting in an increase in intracellular calcium (e.g. via Gq receptor activation leading to Ca2+ release from platelet endoplasmic reticulum Ca2+ stores, which may activate PKC). Hence, this calcium increase triggers the calcium-dependent association of gpIIb and gpIIIa to form the activated membrane receptor complex gpIIb/IIIa, which is capable of binding fibrinogen (factor I), resulting in many platelets "sticking together" as they may connect to the same strands of fibrinogen, resulting in a clot. The coagulation cascade then follows to stabilize the clot, as thrombin (factor IIa) converts the soluble fibrinogen into insoluble fibrin strands. These strands are then cross-linked by factor XIII to form a stabilized blood clot.

# Pathology
Defects in glycoprotein IIb/IIIa cause Glanzmann's thrombasthenia.
Autoantibodies against IIb/IIIa can be produced in immune thrombocytopenic purpura.

# Medicine
Glycoprotein IIb/IIIa inhibitors can be used to prevent blood clots in an effort to decrease the risk of heart attack or stroke.
Genital ulcer disease
Synonyms and keywords: GUD

# Overview
Genital ulcer disease (GUD) can be defined as diseases characterized by genital, anal, or perianal lesions that are ulcerative or pustular. GUD is typically caused by sexually transmitted infections (STI) but also by other non-STI conditions.
Sexually transmitted diseases characterized as GUD include:
- Chancroid
- Genital herpes
- Donovanosis (granuloma inguinale)
- Lymphogranuloma venereum (LGV)
- Syphilis
Other conditions that are not sexually transmitted infections that may be associated with genital, anal, and perianal lesions include:
- Genital candidiasis
- Trauma
- Carcinoma
- Aphthae
- Fixed drug eruption
- Psoriasis
- Behcet's disease

# Differentiating Genital Ulcer Diseases
Sexually transmitted diseases characterized as GUD may present with similar manifestations and lesion characteristics. A diagnosis based only on the patients medical history and physical examination frequently is inaccurate. Patients who have genital, anal, or perianal ulcers should be evaluated with laboratory tests to make a definitive diagnosis.
Homologation reaction
A homologation reaction, also known as homologization, is any chemical reaction that effects an overall increase of the carbon skeleton of a saturated reactant molecule. The reactants undergo a homologation converting them into the next member of the homologous series. For example the reaction of aldehydes and ketones with diazomethane or methoxymethylenetriphenylphosphine effectively inserts a methylene (-CH2-) unit in the hydrocarbon chain and the reaction product is the next homologue.
Examples of homologation reactions include:
- Seyferth-Gilbert homologation
- Displacement of a halide by a cyanide group, which can be reduced to an amine
- Kiliani-Fischer synthesis, where an aldose molecule is elongated through a three-step process consisting of:
Nucleophillic addition of cyanide to the carbonyl to form a cyanohydrin
Hydrolysis to form a lactone
Reduction to form the homologous aldose
- Nucleophillic addition of cyanide to the carbonyl to form a cyanohydrin
- Hydrolysis to form a lactone
- Reduction to form the homologous aldose
- Wittig reaction of an aldehyde with methoxymethylenetriphenylphosphine, which produces a homologous aldehyde.
- Arndt-Eistert synthesis is a series of chemical reactions designed to convert a carboxylic acid to a higher carboxylic acid homologue (ie. contains one additional carbon atom)
- Kowalski ester homologation, an alternative to the Arndt-Eistert synthesis. Has been used to convert -amino esters from -amino esters through an ynolate intermediate.
Some reactions increase the chain length by more than one unit. For example, the following are considered two-carbon homologation reactions:
- Nucleophilic addition to ethylene oxide, resulting in a ring-opening and producing a primary alcohol with two extra carbons.
- Malonic ester synthesis, which produces a carboxylic acid with two extra carbons.
Gastroduodenal artery
In anatomy, the gastroduodenal artery is a small blood vessel in the abdomen.
It supplies blood to the pylorus (distal part of the stomach) and the proximal part of the duodenum.
It arises from the common hepatic artery and terminates in a bifurcation, when it splits into the right gastroepiploic artery and the anterior superior pancreaticoduodenal artery.

# Pathology
The gastroduodenal artery can be the source of a significant gastrointestinal bleed, which may arise as a complication of peptic ulcer disease.
Gaultheria procumbens
Gaultheria procumbens, also known as the Eastern Teaberry, Checkerberry, Boxberry and American Wintergreen, is a small shrub native to northeastern North America. It is low-growing, typically reaching 1015 cm tall. The leaves are evergreen, elliptic to ovate, 25 cm long and 12 cm broad, with a distinct oil of wintergreen scent. The flowers are bell-shaped, 68 mm long, white, borne solitary or in short racemes. The fruit is an edible red berry 815 mm diameter.
The species is endangered in parts of its native range.
While most people, even those living in the mid-Atlantic United States, have never tasted teaberry, somewhat more have tried chewing gums faithful to the taste of the berry.  Traditionally it was common to pick and chew a leaf much as one would chew gum.
Its leaves and branches also make a fine tea, through normal drying and infusion process.
Teaberry is also an ice cream flavor in regions where the plant grows.
In order for the leaves to produce more than a whiff of the minty methyl salicylate, they need to be fermented in warm water for several days before drinking.
Gemtuzumab ozogamicin

# Overview
Gemtuzumab ozogamicin (marketed by Wyeth as Mylotarg) is a drug-linked monoclonal antibody (an antibody-drug conjugate) that was used to treat acute myelogenous leukemia from 2000 to 2010.  It was withdrawn from market in June 2010 when a clinical trial showed the drug increased patient death and added no benefit over conventional cancer therapies.
Gemtuzumab is a monoclonal antibody to CD33 linked to a cytotoxic agent from the class of calicheamicins.  CD33 is expressed in most leukemic blast cells but also in normal hematopoietic cells, the intensity diminishing with maturation of stem cells.   In the United States, it was approved under an accelerated-approval process by the FDA in 2000 for use in patients over the age of 60 with relapsed acute myelogenous leukemia (AML); or those who are not considered candidates for standard chemotherapy.
Within the first year after approval,  the FDA required a black box warning be added to Gemtuzumab packaging.  The drug was noted to increase the risk of veno-occlusive disease in the absence of bone marrow transplantation.  Later the onset of VOD was shown to occur at increased frequency in Gemtuzumab patients even following bone marrow transplantation. The drug was discussed in a 2008 JAMA article, which criticized the inadequacy of postmarketing surveillance  of biologic agents.
Common side effects of administration included shivering, fever, nausea and vomiting. Serious side effects included severe myelosuppression (suppressed activity of bone marrow, which is involved in formation of various blood cells ), disorder of the respiratory system, tumor lysis syndrome, Type III hypersensitivity, venous occlusion, and death.

# Withdrawal from market
A randomized phase 3 comparative controlled trial (SWOG S0106) was initiated in 2004 by Wyeth in accordance with the FDA accelerated-approval process.  The study was stopped prior to completion due to worrisome outcomes.  Among the patients evaluated, fatal toxicity rate was significantly higher in the gemtuzumab combination therapy group vs the standard therapy group. Mortality was 5.7% with gemtuzumab and 1.4% without the agent (16/283 = 5.7% vs 4/281 = 1.4%; P = .01).
In June 2010, Pfizer withdrew Mylotarg from the market at the request of the US FDA.  However, some other regulatory authorities did not agree with the FDA decision, with Japan's Pharmaceuticals and Medical Devices Agency stating in 2011 that the "risk-benefit balance of gemtuzumab ozogamicin has not changed from its state at the time of approval".