fatty diacid is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-11-09. Numbers and descriptions here follow the published literature rather than marketing material.
Semaglutide is a synthetic peptide analog of human glucagon-like peptide-1, a gut hormone released after meals. Its backbone retains the GLP-1 sequence but incorporates two substitutions that slow enzymatic breakdown by dipeptidyl peptidase-4. A short polyethylene glycol linker and a C18 fatty diacid are attached to the peptide chain, allowing the molecule to bind serum albumin and remain in circulation far longer than the native hormone. The result is a circulating half-life measured in days rather than the minutes typical of endogenous GLP-1.
Receptor activation occurs at GLP-1 receptors distributed across pancreatic islets, the hypothalamus, and the gastrointestinal tract. Binding triggers G protein signaling that raises cyclic AMP and enhances glucose-dependent insulin release. Because the effect depends on prevailing glucose levels, insulin secretion does not rise when blood sugar is already low. Signaling in the brain and gut also influences appetite and gastric emptying, which is why the compound appears in both metabolic and weight-related research literature.
Development began in the early 2010s with the goal of extending GLP-1 activity beyond the brief window achieved by native peptide infusion. The earliest approved formulation was a subcutaneous injection given once weekly. A later oral tablet pairs the peptide with an absorption enhancer, sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, usually shortened to SNAC. That carrier lowers local pH and helps the peptide cross gastric tissue. Both routes deliver the same active molecule.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1 (GLP-1), a hormone released from intestinal L-cells after food intake. The compound belongs to the incretin mimetic class and acts at GLP-1 receptors distributed across pancreatic, gastrointestinal, cardiovascular, and central nervous system tissues. Compared with native GLP-1, the molecule carries structural changes that extend its activity from minutes to roughly one week. It is studied for glycemic control in type 2 diabetes and for weight management, and its effects on cardiovascular and other outcomes remain active research areas.
Receptor binding triggers G protein signaling that raises intracellular cyclic AMP in pancreatic beta cells. Insulin release follows in a glucose-dependent manner, so secretion increases when blood glucose is elevated and diminishes when it is not. The same signaling suppresses glucagon release from alpha cells and slows gastric emptying, which blunts the post-meal glucose rise. In the brain, receptor activation in regions such as the arcuate nucleus is associated with reduced appetite and lower energy intake. How much each of these effects contributes to overall weight change is not fully settled.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide, GLP-1 receptor agonist | Not a small molecule |
| Backbone substitutions | Non-natural residue at position 8, arginine at position 34 | Slows enzymatic cleavage |
| Side chain | C18 fatty diacid with PEG linker | Enables albumin binding |
| Approximate molecular mass | 4114 Da | Varies slightly with salt form |
| Reported half-life | About one week | Longer than native GLP-1 by orders of magnitude |
Psilocybin is dephosphorylated into its active form psilocin in the body and hence is a prodrug. Psilocybin is metabolized in the intestines, liver, kidneys, blood, and other tissues and bodily fluids. There is significant first-pass metabolism of psilocybin and psilocin with oral administration. No psilocybin has been detected in the blood in humans after oral administration, suggesting virtually complete dephosphorylation into psilocin with the first pass. It is also said to be converted 90% to 97% into psilocin. The competitive phosphatase inhibitor β-glycerolphosphate, which inhibits psilocybin dephosphorylation, greatly attenuates the behavioral effects of psilocybin in rodents. Psilocybin undergoes dephosphorylation into psilocin via the acidic environment of the stomach or the actions of alkaline phosphatase (ALP) and non-specific esterases in tissues and fluids. Psilocin is demethylated and oxidatively deaminated by monoamine oxidase (MAO), specifically monoamine oxidase A (MAO-A), into 4-hydroxyindole-3-acetaldehyde (4-HIAL or 4-HIA). 4-HIAL is then further oxidated into 4-hydroxyindole-3-acetic acid (4-HIAA) by aldehyde dehydrogenase (ALDH) or into 4-hydroxytryptophol (4-HTOL or 4-HTP) by alcohol dehydrogenase (ALD). Deamination of psilocin by MAO-A appears to be responsible for about 4% or 33% of its metabolism in different studies. In contrast to psilocin, its metabolites 4-HIAA and 4-HTP showed no affinity for or activation of multiple serotonin receptors and are considered inactive.
Other biologists dispute this conception and emphasize the community metabolism theme, the idea that early living communities would comprise many different entities to extant cells, and would have shared their genetic material more extensively than current microbes.
Compounds begin to break down as soon as they enter the body. The majority of small-molecule drug metabolism is carried out in the liver by redox enzymes, termed cytochrome P450 enzymes. As metabolism occurs, the initial (parent) compound is converted to new compounds called metabolites. When metabolites are pharmacologically inert, metabolism deactivates the administered dose of parent drug and this usually reduces the effects on the body. Metabolites may also be pharmacologically active, sometimes more so than the parent drug (see prodrug).
Sources: en.wikipedia.org
The hydrostatic effect of variable ballast tanks is not the only way to control the submarine underwater. Hydrodynamic maneuvering is done by several control surfaces, collectively known as diving planes or hydroplanes, which can be moved to create hydrodynamic forces when a submarine moves longitudinally at sufficient speed. In the classic cruciform stern configuration, the horizontal stern planes serve the same purpose as the trim tanks, controlling the trim. Most submarines additionally have forward horizontal planes, normally placed on the bow until the 1960s but often on the sail on later designs, where they are closer to the center of gravity and can control depth with less effect on the trim.
Some hormonal birth control methods utilize cervical drug delivery methods. The earliest example of such dates to 1850 Ancient Egypt when acadia gum was inserted into the vagina, releasing spermicidal components. Examples in the modern era include vaginal rings and intrauterine devices (IUDs) that release hormones into the reproductive system to prevent fertilization. Vaginal rings are plastic ring-shaped devices that are inserted into the vaginal canal and slowly release hormones such as estradiol or progestin. Hormonal IUDs are T-shaped devices inserted into the uterus, releasing progestin over extended periods of time. These hormones work to thicken the cervical mucus to prevent sperm from penetrating and reaching the fallopian tubes. Copper IUDs are another form of intrauterine devices that release copper ions instead of hormones. The copper ions are toxic to sperm and therefore prevents successful fertilization.
Intradialytic parenteral nutrition (IDPN) is a nutritional support therapy (medical nutrition therapy) for people on hemodialysis who have a difficult time maintaining adequate nutrition. It is administered directly into the bloodstream of patients with chronic kidney disease (CKD) in an effort to decrease the associated morbidity and mortality experienced in patients with kidney failure. IDPN contains protein (amino acids), carbohydrates (dextrose), and fats (lipids) in an attempt to meet a patient's weekly nutritional needs. Solutions can be individualized for each patient based on weight, needs, medical history and enteral intake.
Sources: en.wikipedia.org
30 October – A study finds that the world's remaining carbon budget for 1.5 °C of global warming is only half that of previous estimates, at less than 250 gigatonnes of carbon dioxide, or around six years of annual worldwide emissions. 31 October The first discovery of a virus, phage MiniFlayer, that attaches to another helper virus is reported. The coalition of research organizations and science funders behind Plan S publishes a proposal for moving scholarly communication towards open science practices that are more transparent, accessible, efficient and without author fees. Hazard research is published: a study further confirms noncompensable moist heat extremes will be beyond bounds of past human evolutionary environments for billions of people (9 Oct), an analysis calls for health policy regarding unhealthy ultra-processed foods (9 Oct), an analysis calls for action regarding the summarized environmental footprint of bitcoin mining (9 Oct), a global assessment of risk from increasing pollinator loss to crop pollination shows cocoa and coffee at high risk (12 Oct), a training data poisoning technique, 'Nightshade', against generative AI software specific to select prompts is described (20 Oct), a study indicates low deep sleep percentage is a modifiable dementia risk factor (30 Oct).
=== Homocysteine === Homocysteine, a non-protein amino acid and analogue to the protein amino acid cystine, has been shown to have negative effects on bone health. Higher homocysteine concentrations are likely a result of folate, vitamin B12 B6 deficiencies. In addition, it was found that homocysteine concentration was significantly affected by physical activity. The stimulation of the skeleton through physical activity promotes positive bone remodelling and decreases levels of homocysteine, independently from nutritional intake. Four methods have been proposed regarding the interaction of homocysteine and bone; increase in osteoclast activity, decrease in osteoblast activity, decrease in bone blood flow, and direct action of homocysteine on bone matrix. Homocysteine inhibits lysyl oxidase which is responsible for post-translational modifications of collagen, a key component to bone structure
Potassium is a chemical element; it has symbol K (from Neo-Latin kalium) and atomic number 19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium peroxide in only seconds of exposure. It was first isolated from potash, the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals, all of which have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge (which combines with anions to form salts). In nature, potassium occurs only in ionic salts. Elemental potassium reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction, and burning with a lilac-colored flame. It is found dissolved in seawater (which is 0.04% potassium by weight), and occurs in many minerals such as orthoclase, a common constituent of granites and other igneous rocks. Potassium is chemically very similar to sodium, the previous element in group 1 of the periodic table. They have a similar first ionization energy, which allows for each atom to give up its sole outer electron. It was first suggested in 1702 that they were distinct elements that combine with the same anions to make similar salts, which was demonstrated in 1807 when elemental potassium was first isolated via electrolysis. Naturally occurring potassium is composed of three isotopes, of which 40K is radioactive.
== Appointments == Kahn became the president and director of Joslin in 2000 and held this position until 2007. In 2012, he was appointed Joslin's first Chief Academic Officer. Outside of Joslin, Kahn also held various leadership roles. In 1998 he was appointed chair of the Congressionally-mandated Diabetes Research Working Group (DRWG). This group developed a strategic plan which served as the roadmap for growth of the diabetes research for the United States over the following 10 years. Dr. Kahn also served as chair of Class IV (Biomedical Sciences) of the National Academy of Sciences from 2007 to 2010.
Sources: en.wikipedia.org
Native GLP-1 is degraded within minutes by circulating enzymes. The synthetic version carries substitutions at positions that block enzymatic cleavage, plus a fatty acid side chain that promotes albumin binding. These two changes together extend circulation time from minutes to roughly a week.
Albumin binding keeps a large fraction of the compound in a slowly released reservoir within the bloodstream. Plasma levels decline gradually rather than falling sharply after each administration. That profile supports dosing intervals measured in days instead of hours.
The active peptide sequence is the same in both formats. The oral version adds an absorption enhancer that is not present in the injected solution. Differences in excipients and formulation affect uptake rather than the identity of the active molecule.
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and cleared quickly. Semaglutide carries a position 8 substitution that blocks that cleavage and a fatty diacid chain that binds albumin. Together these changes extend its circulating half-life to about one week.