A practical reference on somatotroph: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-03-14. Anything still debated is marked as such rather than presented as settled.
CJC-1295 is a synthetic peptide analog of growth hormone-releasing hormone, constructed on the 29-amino-acid fragment designated GRF(1-29). The name began as an internal development code during the 1990s and later spread through research supply catalogs and discussion forums. The molecule does not occur in nature; its sequence is engineered rather than isolated from tissue. Two related compounds are sold under this single label, and they differ by one appended chemical group that strongly influences how long the peptide remains in circulation.
The dividing feature between the two forms is a maleimide-based drug affinity complex, abbreviated DAC. In the DAC-bearing version, a linker attaches the peptide to serum albumin after administration, and that association slows removal from plasma. The version lacking DAC appears in catalogs as MOD GRF(1-29) or tetrasubstituted GRF(1-29). Because informal writing treats both as one item, comparisons drawn from such sources routinely blend measurements taken from two molecules with substantially different behavior.
CJC-1295 acts at the growth hormone-releasing hormone receptor, a G-protein-coupled receptor found on somatotroph cells in the anterior pituitary. Binding triggers a rise in cyclic AMP and calcium entry, which promotes release of stored growth hormone. Because the peptide mimics the body's own releasing hormone, it amplifies existing secretory pulses rather than driving continuous output. The size of the response therefore depends partly on the subject's own hormonal rhythm and feedback state.
The attached maleimide group explains the unusual duration of the DAC version. After injection it reacts with the thiol of cysteine-34 on serum albumin, forming a stable covalent bond. The resulting conjugate is too large for rapid kidney filtration and is shielded from many peptidases. Reported half-lives for this form reach several days, whereas the version without the group is cleared in roughly half an hour. That gap is the main pharmacological difference between the two.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | Analog of growth hormone-releasing hormone |
| Chain length | 29 amino acids | Based on the GRF(1-29) fragment |
| Appearance | White to off-white lyophilized powder | Common research supply form |
| Solubility | Soluble in water and aqueous buffers | Powder requires reconstitution before use |
| Typical storage | −20 °C or below | Kept away from light and moisture |
Two related peptides circulate under the CJC-1295 label, and they differ mainly in how long they persist in circulation. The version carrying a drug affinity complex includes a maleimidopropionic acid linker that forms a covalent bond with serum albumin. The other version, usually written as modified GRF(1-29) or tetrasubstituted GRF(1-29), lacks that linker and is cleared quickly. Mixing the two produces inconsistent readings of published half-life values, because the linker rather than the receptor-facing sequence drives most of the difference.
The core sequence keeps the receptor-binding region of GHRH while replacing four positions that are vulnerable to dipeptidyl peptidase-4 and other proteases. Substitutions at positions 2, 8, 15, and 27 raise metabolic stability relative to the natural hormone. The N-terminal residues remain essential for activity, so changes there generally lower potency. Molecular weight sits near 3368 daltons for the tetrasubstituted analog without the linker, while the albumin-binding form is heavier because of the added maleimide group.
Both forms act at the pituitary receptor for growth hormone-releasing hormone and increase growth hormone output, which in turn raises insulin-like growth factor 1. A long-acting analog produces sustained rather than pulsatile stimulation, and the physiological consequences of that pattern are not fully settled. Published human data on the extended form remain limited, and much of what circulates in discussion traces to early company reports rather than independent replication. How sustained exposure affects normal feedback remains an open question.
The distinguishing feature of the DAC form is a maleimide-containing group that reacts with the free thiol of cysteine-34 on human serum albumin. This reaction forms a covalent bond without enzymatic assistance, and it takes place after the peptide enters the bloodstream. Because albumin is abundant and long-lived, the attached peptide is carried through circulation far longer than an unmodified fragment would survive. The chemistry is a deliberate pharmacokinetic strategy rather than a change to receptor activity.
Enzymatic protection is a separate mechanism from plasma protein binding. The four substitutions in the backbone reduce recognition by dipeptidyl peptidase IV, which normally cleaves the natural hormone within minutes. Without the reactive group, this resistance still yields only a short window of activity, generally reported in the range of tens of minutes. With it, reported half-lives in early human work extended to several days. The size of that gap is the main practical distinction between the two materials.
== Reactions == The imidazole groups on TCDI can be easily displaced, allowing it to act as a safer alternative to thiophosgene. This behaviour has been used in the Corey–Winter olefin synthesis. It may also replace thioacyl chlorides (RC(S)Cl) in the Barton–McCombie deoxygenation. Other uses include the synthesis of thioamides and thiocarbamates. Like the analogous CDI, it may be used for peptide coupling.
Some catsharks (Scyliorhinidae) and the finback catsharks in the genus Proscyllium are the only members of their order that lay eggs. The egg cases of catsharks are purse-shaped with long tendrils at the corners that serve to anchor them to structures on the sea floor. The size of egg cases vary; those of the small-spotted catshark or lesser spotted dogfish, Scyliorhinus canicula, are around 5 centimetres (2 in) long, while those of the greater spotted dogfish, S. stellaris, are around 10 centimetres (4 in). That excludes the four long tendrils found in each corner, which assist in anchorage. Egg cases from rays vary in that they have points rather than tendrils. The colours and shapes of egg cases also vary greatly from species to species.
== Terminology == Tendinitis is a very common, but misleading term. By definition, the suffix "-itis" means "inflammation of". Inflammation is the body's local response to tissue damage which involves red blood cells, white blood cells, blood proteins with dilation of blood vessels around the site of injury. Tendons are relatively avascular. Corticosteroids are drugs that reduce inflammation. Corticosteroids can be useful to relieve chronic tendinopathy pain, improve function, and reduce swelling in the short term. However, there is a greater risk of long-term recurrence. They are typically injected along with a small amount of a numbing drug called lidocaine. Research shows that tendons are weaker following corticosteroid injections. Tendinitis is still a very common diagnosis, though research increasingly documents that what is thought to be tendinitis is usually tendinosis. Anatomically close but separate conditions are:
Sources: en.wikipedia.org
Scar revision is a process of cutting the scar tissue out. After the excision, the new wound is usually closed up to heal by primary intention, instead of secondary intention. Deeper cuts need a multilayered closure to heal optimally, otherwise depressed or dented scars can result. Surgical excision of hypertrophic or keloid scars is often associated to other methods, such as pressotherapy or silicone gel sheeting. Lone excision of keloid scars, however, shows a recurrence rate close to 45%. A clinical study is currently ongoing to assess the benefits of a treatment combining surgery and laser-assisted healing in hypertrophic or keloid scars. Subcision is a process used to treat deep rolling scars left behind by acne or other skin diseases. It is also used to lessen the appearance of severe glabella lines, though its effectiveness in this application is debatable. Essentially the process involves separating the skin tissue in the affected area from the deeper scar tissue. This allows the blood to pool under the affected area, eventually causing the deep rolling scar to level off with the rest of the skin area. Once the skin has leveled, treatments such as laser resurfacing, microdermabrasion or chemical peels can be used to smooth out the scarred tissue.
Kr + F2 → KrF2 Krypton gas in a krypton fluoride laser absorbs energy from a source, causing the krypton to react with fluorine gas, producing the exciplex krypton fluoride, a temporary complex in an excited energy state:
=== Prey === Rattlesnakes typically consume mice, rats, rabbits, ground squirrels, gophers, prairie dogs, ground-nesting birds and other small animals (such as lizards, frogs, toads and occasionally American mink and weasels). They lie in wait for their prey, or hunt for it in holes. The rattlesnake's defence and hunting mechanisms are bound to its physiology and its environment. More importantly environmental temperature can influence the ability of ectotherms. The prey is killed quickly with a venomous bite as opposed to constriction. If the bitten prey moves away before dying, the rattlesnake can follow it by its scent. When it locates the fallen prey, it checks for signs of life by prodding with its snout, flicking its tongue, and using its sense of smell. Once the prey has become incapacitated, the rattlesnake locates its head by odors emitted from the mouth. The prey is then ingested head first, which allows wings and limbs to fold at the joints in a manner that minimizes the girth of the meal. The gastric fluids of rattlesnakes are extremely powerful, allowing for the digestion of flesh and bone. Optimal digestion occurs when the snake maintains a body temperature between 80 and 85 °F (27 and 29 °C). If the prey is small, the rattlesnake often continues hunting. If the meal was adequate, the snake finds a warm, safe location in which to coil up and rest until the prey is digested. Feeding habits play an important ecological role by limiting the size of rodent populations, which prevents crop damage and stabilizes ecosystems.
Liu Wenhui travelled to Chongqing to negotiate with Liu Xiang, but Liu Xiang would not hand over the confiscated shipment. This was because Liu Xiang had a policy of not allowing any other Sichuanese warlord to gain aircraft (he himself had already acquired a rudimentary air force consisting of several Potez 25 and Breguet 14 bombers). Western sources also agree that Liu Wenhui tried obtaining aircraft, although according to them the aircraft were either seized in Hankou by the central government or crashed en route to Chengdu. The Chinese sources go further by asserting that in May 1931, Liu Wenhui attempted to bribe Liu Xiang's subordinates, including Fan Shaozhen, to join him, but they reported this matter to Liu Xiang, causing Liu to waste 450,000 yuan. An angered Liu supposedly then cut off Liu Xiang's grain supply, forcing the Chongqing warlord to urgently purchase grain from Hunan to prevent hunger. Whatever the matter, it is clear that Liu Wenhui's once-cooperative relationship with his nephew, General Liu Xiang, had soured and turned into a rivalry. On 19 October 1932, Liu Xiang's general, Tang Shizun, and ninety-four other Sichuanese warlords issued a circular telegram to denounce Liu Wenhui. The telegram asserted that Liu was power-hungry, unscrupulous, corrupt, and nepotistic, with no real plans for governing Sichuan and resorting to underhanded tactics such as bribery, backstabbing, and banditry to gain and maintain power. On the eve of war in 1932, Liu Wenhui's armies were estimated at around 120,000 men, slightly outnumbering Liu Xiang's 100,000.
Sources: en.wikipedia.org
Some enzymes do not need additional components to show full activity. Others require non-protein molecules called cofactors to be bound for activity. Cofactors can be either inorganic (e.g., metal ions and iron–sulfur clusters) or organic compounds (e.g., flavin and heme). These cofactors serve many purposes; for instance, metal ions can help in stabilizing nucleophilic species within the active site. Organic cofactors can be either coenzymes, which are released from the enzyme's active site during the reaction, or prosthetic groups, which are tightly bound to an enzyme. Organic prosthetic groups can be covalently bound (e.g., biotin in enzymes such as pyruvate carboxylase). An example of an enzyme that contains a cofactor is carbonic anhydrase, which uses a zinc cofactor bound as part of its active site. These tightly bound ions or molecules are usually found in the active site and are involved in catalysis. For example, flavin and heme cofactors are often involved in redox reactions. Enzymes that require a cofactor but do not have one bound are called apoenzymes or apoproteins. An enzyme together with the cofactor(s) required for activity is called a holoenzyme (or haloenzyme). The term holoenzyme can also be applied to enzymes that contain multiple protein subunits, such as the DNA polymerases; here the holoenzyme is the complete complex containing all the subunits needed for activity.
PCP is both water- and lipid-soluble and is therefore distributed throughout the body quickly. PCP is metabolized into PCHP, PPC and PCAA. The drug is metabolized 90% by oxidative hydroxylation in the liver during the first pass. Metabolites are glucuronidated and excreted in the urine. Nine percent of ingested PCP is excreted in its unchanged form. When smoked, some of the compound is broken down by heat into 1-phenylcyclohexene (PC) and piperidine. The time taken before the effects of PCP manifest is dependent on the route of administration. The onset of action for inhalation occurs in 2–5 minutes, whereas the effects may take 15 to 60 minutes when ingested orally.
=== Biological activity === Met-enkephalin is a potent agonist of the δ-opioid receptor, and to a lesser extent the μ-opioid receptor, with little to no effect on the κ-opioid receptor. It is through these receptors that met-enkephalin produces its opioid effects, such as analgesia and antidepressant-like effects. It is also the endogenous ligand of the opioid growth factor receptor (OGFR; formerly known as the ζ-opioid receptor), which plays a role in the regulation of tissue growth and regeneration; hence why met-enkephalin is sometimes called OGF instead.
Management of obesity can include lifestyle changes, medications, or surgery. Although many studies have sought effective interventions, there is currently no evidence-based, well-defined, and efficient intervention to prevent obesity. Treatment for obesity often consists of weight loss via healthy nutrition and increasing physical exercise. A 2007 review concluded that certain subgroups, such as those with type 2 diabetes and women who undergo weight loss, show long-term benefits in all-cause mortality, while long‐term outcomes for men are "not clear and need further investigation." The most effective treatment for obesity is bariatric surgery. Surgery for severe obesity is associated with long-term weight loss and decreased overall mortality. One study found a weight loss of between 14% and 25% (depending on the type of procedure performed) at 10 years, and a 29% reduction in all cause mortality when compared to standard weight loss measures. Another study also found reduced mortality in those who underwent bariatric surgery for severe obesity. Diet programs can produce short-term weight loss and, to a lesser extent, over the long-term. Greater weight loss results, including amongst underserved populations, are achieved when proper nutrition is regularly combined with physical exercise and counseling. Dietary and lifestyle changes are effective in limiting excessive weight gain in pregnancy and improve outcomes for both the mother and the child.
== O == Obex The point in the brainstem where the fourth ventricle narrows to become the central canal of the spinal cord. Used as an anatomical landmark in neuroanatomy. Occipital lobe The rearmost lobe of the cerebral cortex, primarily responsible for visual processing, including interpretation of color, motion, and spatial orientation. Ocular dominance A preference of neurons in the visual cortex for input from one eye over the other. Studied extensively in visual development and plasticity. Oculomotor nerve (Cranial Nerve III) A cranial nerve that controls most of the eye's movements, including those of the eyelid and pupil constriction. Damage may result in diplopia or ptosis. Olfaction The sense of smell, mediated by receptors in the olfactory epithelium and processed in the olfactory bulb and related brain regions. Olfactory bulb The first brain structure to process olfactory (smell) information. Receives input from sensory neurons in the nasal cavity and sends projections to the olfactory cortex and limbic system. Olfactory cortex A region of the brain involved in odor identification and perception. Includes the piriform cortex and parts of the amygdala and entorhinal cortex. Olfactory nerve (Cranial Nerve I) The first cranial nerve, responsible for transmitting smell information from the nose to the brain. Oligodendrocyte A type of glial cell in the central nervous system that forms the myelin sheath around axons, enabling rapid signal conduction.
Sources: en.wikipedia.org
No. It is a laboratory-synthesized analog built on a fragment of the natural hormone. The natural peptide is shorter-lived and lacks the stabilizing substitutions found in the synthetic version.
DAC stands for drug affinity complex, a chemical group that binds the peptide to serum albumin. The binding slows clearance and lengthens the time the molecule stays in plasma compared with the unmodified analog.
Because two distinct molecules are discussed under one informal label. The albumin-binding version clears over several days, while the form without that group clears within roughly half an hour. Mixing results from both creates inconsistent figures.
It binds the growth hormone-releasing hormone receptor on pituitary somatotroph cells. Receptor activation raises cyclic AMP and promotes release of stored growth hormone granules. Because the peptide persists longer than natural releasing hormone, stimulation is prolonged rather than brief.