This is a working overview of DAC linker, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-02-10 and is reviewed periodically as new material appears.
Two related forms circulate in technical discussion under the same family name. The original version carries a drug affinity complex (DAC) that binds covalently to serum albumin after administration, and this linkage substantially extends circulation time. A second form, frequently written as modified GRF(1-29) or CJC-1295 without DAC, lacks that linker and clears much faster. The naming is a frequent source of confusion because the shorthand CJC-1295 can refer to either form depending on the source. Reports sometimes fail to specify which variant was studied.
The peptide backbone includes a D-alanine at position two, which resists cleavage by dipeptidyl peptidase IV, and several other substitutions that reduce degradation. Its molecular weight is roughly 3.4 kDa without the linker and about 3.6 kDa with it. The molecule is water soluble and is normally supplied as a lyophilized powder. Precise sequence and mass values depend on which variant is described, so technical documents usually state the exact form being referenced.
CJC-1295 is a synthetic peptide designed as a long-acting analogue of growth hormone-releasing hormone (GHRH). Its structure derives from the first 29 amino acids of native GHRH, a fragment often called GRF(1-29). Four substitutions were introduced to slow enzymatic breakdown and extend activity relative to the natural sequence. The compound was developed by ConjuChem as part of a broader effort to improve the pharmacokinetic profile of peptide hormones. It is studied in laboratory and clinical research settings rather than appearing as a naturally occurring substance.
CJC-1295 is a synthetic analogue of growth hormone-releasing hormone, built on the 29-amino-acid GHRH(1-29) fragment. Four substitutions distinguish it from the natural sequence: D-alanine at position 2, glutamine at position 8, alanine at position 15, and leucine at position 27. These changes reduce enzymatic cleavage and extend the peptide's persistence in circulation. The compound is discussed in two forms, one carrying a drug affinity complex and one without it.
The drug affinity complex is a maleimidopropionic acid group attached to a lysine side chain. It reacts with the free thiol of cysteine-34 on circulating albumin, forming a covalent bond. This conjugation keeps the peptide in the bloodstream and shields it from rapid renal filtration and proteolysis. Reported circulation half-lives for the albumin-bound form fall in the range of roughly six to nine days in early human studies.
| Property | Value | Notes |
|---|---|---|
| Molecular weight (no linker) | ~3.37 kDa | Calculated from peptide sequence |
| Molecular weight (with linker) | ~3.65 kDa | Includes albumin-binding moiety |
| Appearance | White to off-white powder | Typically lyophilized |
| Solubility | Soluble in water | Also dissolves in aqueous buffers |
| Common synonyms | Modified GRF(1-29), DAC:GRF | Usage varies by source |
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.
Downstream of growth hormone, the liver and other tissues increase production of insulin-like growth factor 1, a mediator of many growth-promoting effects. Studies have documented elevated levels of both hormones after dosing, and the rise from the long-acting form persists longer than that produced by shorter-acting analogues. What remains unclear is whether sustained elevation of these markers translates into meaningful clinical benefit, and whether prolonged exposure carries risks that short trials could not detect.
CJC-1295 belongs to a class of synthetic peptides modeled on growth hormone releasing hormone, a forty-four amino acid signal produced by the hypothalamus. The compound is built from the first twenty-nine residues of the natural sequence, with four substitutions introduced at positions 2, 8, 15 and 27. These changes were designed to slow enzymatic breakdown while preserving receptor activation. The result is a peptide that is shorter than native GHRH and considerably more resistant to ordinary clearance pathways in circulation.
Two related forms appear under the CJC-1295 name. The simpler analogue, commonly written as modified GRF(1-29), carries the four substitutions but no additional conjugation. The second form attaches a maleimidopropionic acid linker to a lysine residue, a modification frequently called the drug affinity complex. That linker reacts with the free thiol on serum albumin to form a covalent bond. Because albumin has a long residence time in blood, the conjugated peptide stays in circulation far longer than the unconjugated analogue.
The albumin-binding version stays in circulation for days, because covalent attachment to serum albumin shields the peptide from rapid filtration and degradation. Reported half-lives for this form fall in the range of several days. The version without the linker is cleared in minutes, with estimates often near thirty minutes in animal work. These figures come from small studies and vary with assay method, species, and route, so they are best read as approximate rather than fixed constants.
Studies in this area generally track growth hormone pulses, insulin-like growth factor 1 concentrations, and occasionally body composition endpoints. Most published human data come from early, small trials, and questions about long-term effects remain open. Whether repeated exposure alters pituitary responsiveness over time is not settled. Analytical work relies on immunoassays for the hormones and on mass spectrometry for the peptide itself, because the two measurements answer different questions.
Certain lithium compounds, also known as lithium salts, are used as psychiatric medication, primarily for bipolar disorder and for major depressive disorder. Lithium is taken orally (by mouth). Common side effects include increased urination, shakiness of the hands, and increased thirst. Serious side effects include hypothyroidism, diabetes insipidus, and lithium toxicity. Blood level monitoring is recommended to decrease the risk of potential toxicity. If levels become too high, diarrhea, vomiting, poor coordination, sleepiness, and ringing in the ears may occur. Lithium is teratogenic and can cause birth defects at high doses, especially during the first trimester of pregnancy. The use of lithium while breastfeeding is controversial; many international health authorities advise against it, and the long-term outcomes of perinatal lithium exposure have not been studied. The American Academy of Pediatrics lists lithium as contraindicated for pregnancy and lactation. The United States Food and Drug Administration (FDA) categorizes lithium as having positive evidence of risk for pregnancy and possible hazardous risk for lactation. Lithium salts are classified as mood stabilizers. Lithium's mechanism of action is not known. In the nineteenth century, lithium was used in people who had gout, epilepsy, and cancer. Its use in the treatment of mental disorders began with Carl Lange in Denmark and William Alexander Hammond in New York City, who used lithium to treat mania from the 1870s onwards, based on now-discredited theories involving its effect on uric acid.
=== Bioelectricity === The potential use of developmental bioelectricity in regenerative medicine is under active investigation, with particular interest in future organ and limb regeneration guided by bioelectric stimulation. Developmental bioelectricity refers to endogenous ion flows and voltage gradients across cell membranes (Vmem) in excitable (able to create an action potential) and non-excitable tissues that provide instructive cues for growth. These bioelectric states, set by ion channels and pumps, are propagated through gap-junction coupling and together with chemical gradients and physical forces they form long-range patterning circuits. Through voltage-sensitive signalling pathways, changes in Vmem modulate gene expression and cell behaviours (proliferation, migration, differentiation), thereby shaping tissue growth and polarity. Experiments in vertebrate and invertebrate models indicate that bioelectric cues can steer regeneration. In Xenopus tadpoles, activating a proton pump (V-ATPase) that moves hydrogen ions out of cells is necessary for tail regrowth and can restore regeneration during a normally refractory stage; in adult Zebrafish, inhibiting the same pump impairs fin regrowth. In Planarians, brief electrical perturbations can cause tail pieces to form heads (including two-headed animals) or to regenerate heads resembling other species. In adult frogs, a 24-hour treatment with a drug-delivering ‘BioDome’ device initiated long-term hindlimb regrowth with multi-tissue repair and functional recovery.
== Playing career == Player is one of the most successful golfers in history, tied for fourth in major championship victories with nine. Along with Arnold Palmer and Jack Nicklaus he is often referred to as one of "The Big Three" golfers of the mid-1960's. From the late 1950s through the late 1970s golf boomed in the United States and around the world and was greatly encouraged by expanded television coverage. Along with Gene Sarazen, Ben Hogan, Jack Nicklaus, Tiger Woods and Rory McIlroy, he is one of only six players to win golf's "career Grand Slam". He completed the Grand Slam in 1965 at the age of 29. At the time, he was the youngest player to do this, though Jack Nicklaus (26) and Tiger Woods (24) subsequently broke this record. Player was the second multiple majors winner from South Africa, following Bobby Locke, then was followed by Ernie Els, and Retief Goosen. Player competed regularly on the U.S. based PGA Tour from the late 1950s. He led the Tour money list in 1961, and went on to accumulate 24 career Tour titles. He also played an exceptionally busy schedule all over the world, and he has been called the world's most traveled athlete. Player has logged more than 26 million km (16 million mi) in air travel – in 2005 it was estimated that he had "probably flown further … than any athlete in history". Player has more victories than anyone else in the South African Open (13) and the Australian Open (7).
Sources: en.wikipedia.org
The image above shows the interpretation of an antibody panel used in serology to detect antibodies towards the most relevant blood group antigens. Each row represents "reference" or "control" red blood cells of donors which have known antigen compositions and are ABO group O. The + symbol means that the antigen is present on the reference red blood cells, and 0 means it is absent; nt means "not tested". The "result" column to the right displays reactivity when mixing reference red blood cells with plasma from the patient in 3 different phases: room temperature, 37 °C and AHG (with anti-human globulin, by the indirect antiglobulin test).
The use of steroids by Bollywood actors has become highlighted in a number of newspaper and web articles where actors and models with previously very thin physiques have in a short period of time developed muscular bodies. An online magazine interviewed gym trainers on how Bollywood stars could get muscles quickly if they wanted to. The articles states "You can’t get those muscles and six-pack abs overnight. Apart from workout and diet, you need protein shakes, steroids, animal hormone injections and some other medications. All this has to be taken correctly and within acceptable levels." Anil Kapoor in an interview slammed leading actors who take steroids. In a 2024 interview, former actor Imran Khan admitted taking steroids as a way to compete with other actors, also hinting at the fact that steroids use could be widespread in Bollywood.
80. Levothyroxine. Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006–. 2026 Sep 15. Levothyroxine (T4) is a normal component of human milk. Limited data on exogenous replacement doses of levothyroxine during breastfeeding indicate no adverse effects in infants. The American Thyroid Association recommends that subclinical and overt hypothyroidism should be treated with levothyroxine in lactating women seeking to breastfeed.[1] Adequate levothyroxine treatment during lactation may normalize milk production in hypothyroid lactating mothers with low milk supply, but does not return milk lipids to normal. Mothers taking levothyroxine because of gestational hypothyroidism may have lower exclusive breastfeeding rates rates at 1 month and increased early formula supplementation.[2] Levothyroxine dosage requirement may be increased in the postpartum period compared to prepregnancy requirements in patients with Hashimoto’s thyroiditis.[3]
Sources: en.wikipedia.org
No. It is a synthetic analogue modeled on the first 29 residues of human GHRH. The substitutions and any linker are laboratory modifications rather than features of the endogenous peptide.
Early development used the albumin-binding form, and a shorter variant was later discussed under the same label. Because the two differ in half-life and handling, ambiguity arises whenever a source omits the variant designation.
The compound derives from that fragment but is not identical to it. The parent fragment lacks the stabilizing substitutions, so its degradation rate and duration of action differ noticeably.
The two share the same 29-amino-acid backbone. CJC-1295 carries an additional albumin-binding moiety that markedly extends its residence time in circulation, while the form without that moiety clears faster. Literature sometimes applies the name loosely to either variant.