Aib substitution comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-10-16. Numbers and descriptions here follow the published literature rather than marketing material.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 or 280 nanometres is widely used to assess purity and to resolve related impurities. Liquid chromatography coupled to mass spectrometry confirms identity through the protonated molecular ion and fragment ions formed in tandem experiments. Capillary electrophoresis and peptide mapping after enzymatic digestion supply complementary information on charge variants and modification sites. Circular dichroism and nuclear magnetic resonance can report on secondary structure in solution. Absolute quantification usually depends on an external standard, and reported purity depends on the detection wavelength and integration parameters chosen.
Lyophilised material appears as a white to off-white cake or powder that is hygroscopic, and containers are usually equilibrated to room temperature before opening to limit condensation. Dissolution is performed in water, phosphate-buffered saline, or a mildly alkaline buffer, since solubility rises above neutral pH. Gentle inversion or low-speed mixing is preferred, because vigorous vortexing can promote surface denaturation and aggregation. Complete dissolution may require several minutes, and brief sonication is sometimes applied. Passing the solution through a 0.22 micrometre membrane removes particulates but does not by itself sterilise the liquid.
Storage at minus 20 degrees Celsius or lower in a desiccated container preserves the peptide for extended periods, while working solutions are commonly held at two to eight degrees Celsius for short intervals. Light exposure and repeated freeze-thaw cycles accelerate degradation, so dividing material into single-use aliquots is generally recommended. Adsorption to glass and plastic surfaces can lower the measured concentration of dilute solutions, particularly below one milligram per millilitre. The degradation routes most often reported for GLP-1 analogues are deamidation, methionine oxidation, and backbone hydrolysis. Relative rates under specific conditions are frequently described only for individual formulations.
The primary target is the GLP-1 receptor, a class B G protein-coupled receptor expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises intracellular cyclic AMP, which potentiates glucose-dependent insulin secretion and lowers glucagon release when blood glucose is elevated. Signalling in the hypothalamus and brainstem is associated with reduced appetite and slower gastric emptying. Because the insulinotropic effect depends on prevailing glucose levels, the hypoglycaemic risk of the peptide alone is described as low in most study settings. The relative contribution of peripheral and central actions remains an active research question.
Large randomised trials in adults with type 2 diabetes and in adults with obesity have reported reductions in body weight and improvements in several cardiovascular risk markers. One outcome trial found a lower incidence of major adverse cardiovascular events in participants with diabetes and established cardiovascular disease. Gastrointestinal effects such as nausea and vomiting are the most frequently reported adverse events and often diminish over time. Changes in lean body mass during weight loss are an area of ongoing investigation. Effects in adolescents and in pregnancy are less well characterised, and current labelling advises against use during pregnancy.
| Property | Value | Notes |
|---|---|---|
| Purity assessment | RP-HPLC, 214 nm | Wavelength affects relative peak areas |
| Identity confirmation | LC-MS/MS | Precursor and fragment ion masses compared |
| Common degradation | Deamidation, oxidation | Amide and methionine residues are main sites |
| Working solution storage | 2-8 °C, short term | Longer holding favours frozen aliquots |
| Adsorption risk | Higher below 1 mg/mL | Glass and plastic surfaces both affected |
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released by intestinal L cells after food intake. The natural hormone acts on pancreatic and central receptors but is degraded within minutes by dipeptidyl peptidase-4 and other peptidases. Semaglutide belongs to the class of long-acting GLP-1 receptor agonists, a group distinguished by structural changes that slow breakdown and extend circulation time. Its development followed earlier short-acting analogues and reflects a general strategy in peptide drug design: preserve receptor activity while blocking proteolytic clearance.
Three structural changes define the molecule. At position 8 an alpha-aminoisobutyric acid residue replaces alanine, which blocks dipeptidyl peptidase-4 cleavage. At position 34 arginine replaces lysine, and at position 26 a lysine carries a C18 fatty diacid attached through a short linker. The fatty chain binds serum albumin, and this albumin association reduces renal filtration and enzymatic attack. The unchanged backbone retains the receptor contacts that produce signalling. The free base has the formula C187H291N45O59 and a molecular weight near 4114 daltons.
The semaglutide sequence is a 31-residue analogue of human GLP-1, altered at three positions relative to the parent hormone. Aminoisobutyric acid replaces alanine at position 8, arginine replaces lysine at position 34, and a lipophilic diacid is attached to lysine 26 through a short linker. These features are reported consistently in the structural literature. The position 8 substitution blocks recognition by dipeptidyl peptidase-4, while the attached chain drives strong, reversible association with a carrier protein in blood.
Receptor activation raises intracellular cyclic AMP through Gs coupling, which promotes glucose-dependent insulin release and suppresses glucagon secretion when blood glucose is elevated. Effects outside the pancreas include slower gastric emptying and altered appetite signalling in the hypothalamus and hindbrain. The relative contribution of each tissue to overall metabolic outcomes remains an area of active investigation. Central mechanisms in particular are inferred mainly from animal models and indirect human measures rather than direct observation.
Serum protein binding dominates the pharmacokinetic profile. The attached chain associates strongly with albumin, shielding the peptide from enzymatic attack and slowing filtration by the kidney. This interaction extends the circulation half-life to roughly one week in humans, which supports weekly administration intervals. An oral version pairs the peptide with an absorption enhancer that transiently alters gastric epithelium, permitting limited uptake; bioavailability by that route is substantially lower than by injection.
Kipa-Williams enjoyed working with Samson, as they got along well and he believed that showed on-screen as Ari and Mia reconcile. He also praised Barrett and explained how they got the chance to explore their characters' histories together, saying "you'll get to see a softer side of Ari in the way that Sam plays her character. And I think people will be surprised at the father figure that he has forgotten he is, or was." The first test of Ari and Mia's new relationship is his involvement with a criminal gang headed up by Paul (Jack Finsterer), which leads to the kidnapping of Chloe, Nikau, Bella, and Ryder Jackson (Lukas Radovich). Mia decides to leave the Bay with Chloe and tells Ari that she regrets letting him back into her life. Kipa-Williams commented that "Ari is heartbroken – he's faced with losing the love of his life." He sympathised with Mia, who is angry about her daughter being kidnapped. He also pointed out that Mia thought Ari had changed, so it "pains" her to think that he is still the same man who could end up in prison again. As Ari is walking along the road, he calls Chloe before she leaves town, and is struck by a car driven by Paul who then speeds off. Kipa-Williams said Ari is "blindsided" by the attack and described it as "a ruthless hit-and-run". Ari suffers multiple injuries and has to be placed in a medically induced coma due to a bleed on the brain. Following Ari's recovery, writers scripted a pregnancy for Mia after the couple agree to try for a baby.
=== Civilian government negotiations === In May 2019, al-Burhan's first international trip was to Egypt to meet Abdel Fattah el-Sisi. His second visit was to the United Arab Emirates, where he met with the de facto ruler of the United Arab Emirates, Mohamed bin Zayed Al Nahyan. Iyad el-Baghdadi, a human rights activist who became famous during the Arab Spring, later interpreted these visits (together with a visit by TMC deputy leader Hemedti to Mohammed bin Salman in Saudi Arabia) as encouragements for the TMC to cancel negotiations with the opposition. This comment by Iyad el-Baghdadi and recent developments and his ties to the Egyptian brotherhood which he established long ago when he studied in Egypt has led to the popular belief that al-Burhan has no interest to lead Sudan to a democratic and civilian state. Despite his promise to establish a civilian government by February 2021 as demanded by numerous protesters, his group seems to consistently isolate the civilian government led by Hamdok in key government decisions.
=== FDA Warning for illegal marketing === On April 17, 2017, LifeVantage was issued a warning letter by the U.S. Food and Drug Administration (FDA) regarding illegal advertising claims on the company's websites suggesting that Protandim can play a role in helping to cure various ailments, including cancer and diabetes. The claims were deemed to be in violation of Section 201(g)(1)(B) of the Federal Food, Drug, and Cosmetic Act [21 U.S.C. § 321(g)(1)(B)].
=== Brand names === Spironolactone is marketed under various brand names throughout the world. The original brand name of spironolactone is Aldactone. Other brand names include Aldactone-A, Berlactone, CaroSpir, Espironolactona, Espironolactona Genfar, Novo-Spiroton, Prilactone (veterinary), Spiractin, Spiridon, Spirix, Spiroctan, Spiroderm (discontinued), Spirogamma, Spirohexal, Spirolon, Spirolone, Spiron, Spironolactone Actavis, Spironolactone Orion, Spironolactone Teva, Spirotone, Tempora (veterinary), Uractone, Uractonum, Verospiron, and Vivitar. Spironolactone is also formulated in combination with a variety of other medications, including with hydrochlorothiazide as Aldactazide, with hydroflumethiazide as Aldactide, Lasilacton, Lasilactone, and Spiromide, with altizide as Aldactacine and Aldactazine, with furosemide as Fruselac, with benazepril as Cardalis (veterinary), with metolazone as Metolactone, with bendroflumethiazide as Sali-Aldopur, and with torasemide as Dytor Plus, Torlactone, and Zator Plus.
Sources: en.wikipedia.org
==== Ukraine ==== According to CrowdStrike from 2014 to 2016, the Russian APT Fancy Bear used Android malware to target the Ukrainian Army's Rocket Forces and Artillery. They distributed an infected version of an Android app whose original purpose was to control targeting data for the D-30 Howitzer artillery. The app, used by Ukrainian officers, was loaded with the X-Agent spyware and posted online on military forums. The attack was claimed by Crowd-Strike to be successful, with more than 80% of Ukrainian D-30 Howitzers destroyed, the highest percentage loss of any artillery pieces in the army (a percentage that had never been previously reported and would mean the loss of nearly the entire arsenal of the biggest artillery piece of the Ukrainian Armed Forces). According to the Ukrainian army this number is incorrect and that losses in artillery weapons "were way below those reported" and that these losses "have nothing to do with the stated cause". In 2014, the Russians were suspected to use a cyber weapon called "Snake", or "Ouroboros," to conduct a cyber attack on Ukraine during a period of political turmoil. The Snake tool kit began spreading into Ukrainian computer systems in 2010. It performed Computer Network Exploitation (CNE), as well as highly sophisticated Computer Network Attacks (CNA). On 23 December 2015 the Black-Energy malware was used in a cyberattack on Ukraine's power-grid that left more than 200,000 people temporarily without power. A mining company and a large railway operator were also victims of the attack.
Targeted screening may be appropriate in a number of situations where hypothyroidism is common: other autoimmune diseases, a strong family history of thyroid disease, those who have received radioiodine or other radiation therapy to the neck, those who have previously undergone thyroid surgery, those with an abnormal thyroid examination, those with psychiatric disorders, people taking amiodarone or lithium, and those with a number of health conditions (such as certain heart and skin conditions). Yearly thyroid function tests are recommended in people with Down syndrome, as they are at higher risk of thyroid disease. Guidelines for England and Wales from the National Institute for Health and Care Excellence (NICE) recommend testing for thyroid disease in people with type 1 diabetes and new-onset atrial fibrillation, and suggests testing in those with depression or unexplained anxiety (all ages), in children with abnormal growth, or unexplained change in behavior or school performance. NICE also recommends screening for celiac disease in people with a diagnosis of autoimmune thyroid disease.
=== Metric ounce === A metric ounce is an approximation of the imperial ounce, US dry ounce, or US fluid ounce. These three customary units vary. However, the metric ounce is usually taken as 25 or 30 ml (0.88 or 1.06 imp fl oz; 0.85 or 1.01 US fl oz) when volume is being measured, or in grams when mass is being measured. The US Food and Drug Administration (FDA) defines the "food labeling ounce" as 30.0 ml (1.06 imp fl oz; 1.01 US fl oz), slightly larger than the 29.6 ml (1.04 imp fl oz; 1.00 US fl oz) fluid ounce. Several Dutch units of measurement have been replaced with informal metric equivalents, including the ons or ounce. It originally meant 1⁄16 of a pound, or a little over 30 g (1.1 oz) depending on which definition of the pound was used, but was redefined as 100 g (3.5 oz) when the country metricated.
Sources: en.wikipedia.org
== Refinements == Archimedes' principle does not consider the surface tension (capillarity) acting on the body. Moreover, Archimedes' principle has been found to break down in complex fluids. There is an exception to Archimedes' principle known as the bottom (or side) case. This occurs when a side of the object is touching the bottom (or side) of the vessel it is submerged in, and no liquid seeps in along that side. In this case, the net force has been found to be different from Archimedes' principle, as, since no fluid seeps in on that side, the symmetry of pressure is broken.
He had no difficulty urinating during the flight and the urine collection system worked well, although transferring urine to storage bags in the cramped capsule proved difficult. Cooper took several naps during the flight, lasting about an hour each. He experienced some discomfort from the pressure suit compressing his knees, which he alleviated by moving his feet slightly upward. Some time before re-entry, Cooper complied with an order to consume a dextroamphetamine tablet to ensure his alertness; he reported not feeling any sleepiness for the remainder of the flight.
== History == Benorterone was developed in the late 1950s, was first reported to possess antiandrogenic activity in 1964, and was investigated in clinical trials in the mid-to-late 1960s. It was the first known antiandrogen to be studied in humans. The drug was found to be effective in the treatment of acne, seborrhea, and hirsutism in women. In addition, unlike progestogenic antiandrogens such as cyproterone acetate, it seldom produced side effects in women and did not affect menstruation. However, in males, benorterone was not effective for acne, and produced high rates of gynecomastia (in 12 out of 13 or 92% of young men treated with 75 to 300 mg/day benorterone). Shortly following the observance of this side effect, it was withdrawn from clinical studies. Subsequently, cyproterone acetate, which has a greatly reduced risk of gynecomastia by virtue of its concomitant progestogenic and antigonadotropic actions (which results in suppression of estrogen levels), was developed instead and was introduced for medical use in 1973. In addition, spironolactone, a steroidal antimineralocorticoid that was introduced for medical use in 1959, was discovered to possess potent antiandrogenic activity in 1969, and became widely used clinically as an antiandrogen after its first use in an androgen-dependent condition in 1978.
Sources: en.wikipedia.org
Filtering removes particulate matter that can block columns or scatter light. A 0.22 micrometre membrane is typical, and the filter material should be checked for peptide adsorption.
Peptides can bind to glass and plastic, so a fraction of the material leaves the solution. The effect is proportionally larger in dilute samples and can bias quantitative results.
Reverse-phase high-performance liquid chromatography is the most widely reported approach. Purity figures should always be quoted together with the wavelength, gradient, and integration parameters used.
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and neutral endopeptidases. Semaglutide carries a non-natural amino acid at position eight that blocks that cleavage, and a fatty diacid side chain that binds albumin. The result is a much longer duration of action than the native hormone.