If you have been reading about freeze-thaw and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-08-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Once in circulation, the peptide binds the growth hormone-releasing hormone receptor displayed on pituitary somatotroph cells. Receptor activation couples to Gs proteins, elevates intracellular cyclic AMP, and drives protein kinase A signaling inside the cell. That cascade increases discharge of growth hormone into the bloodstream. The analog therefore operates through a receptor pathway that already exists for the body's own releasing hormone, rather than through an engineered artificial target.
Clearance profiles diverge sharply between the two versions. The albumin-binding molecule stays in plasma for several days, whereas the unmodified analog is largely gone within about half an hour in reported work. Cleavage by dipeptidyl peptidase IV is a major contributor to the short life of the unmodified sequence. These gaps mean the two versions cannot be substituted for each other in study design or in reading results side by side.
| 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.
Lyophilised powder is the usual supplied form. The material is hygroscopic, so vials are typically equilibrated to room temperature before opening in order to prevent condensation on the contents. Long-term storage is generally described at minus twenty degrees Celsius or colder, protected from light and moisture. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of soluble material. A reconstituted solution is considerably less stable than the dry powder and is normally kept refrigerated for short periods only.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography combined with mass spectrometry. The chromatographic separation resolves the target peptide from truncation products and from species carrying oxidised residues, while mass measurement confirms the expected molecular mass. Because the two common variants differ by roughly 280 daltons, a mass determination distinguishes them unambiguously. Purity is often quoted as a percentage of total peak area, although that figure depends on the detection wavelength and the integration method applied.
Binding of the peptide to the growth hormone-releasing hormone receptor on pituitary somatotrophs triggers a G protein coupled cascade that raises cyclic AMP and opens calcium channels. The result is greater secretion of growth hormone into the bloodstream. Because the peptide acts at the same receptor as the natural hypothalamic hormone, its effect is amplified pulse size rather than an entirely separate release pathway. Receptor binding alone does not determine the response, since somatostatin tone and other inputs modulate the final output.
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.
After the successful completion of all the basic and middle education years, a high-school diploma is awarded. The high-school graduate is known as a bachiller, because secondary basic school and middle education are traditionally considered together as a unit called bachillerato (sixth to eleventh grade). Students in their final year of middle education take the ICFES test (now renamed Saber 11) to gain access to higher education (Educación superior). This higher education includes undergraduate professional studies, technical, technological and intermediate professional education, and post-graduate studies. Technical professional institutions of Higher Education are also opened to students holder of a qualification in Arts and Business. This qualification is usually awarded by the SENA after a two years curriculum. Bachilleres (high-school graduates) may enter into a professional undergraduate career program offered by a university; these programs last up to five years (or less for technical, technological and intermediate professional education, and post-graduate studies), even as much to six to seven years for some careers, such as medicine. In Colombia, there is not an institution such as college; students go directly into a career program at a university or any other educational institution to obtain a professional, technical or technological title. Once graduated from the university, people are granted a (professional, technical or technological) diploma and licensed (if required) to practice the career they have chosen.
DHA (dihydroxyacetone, also known as glycerone) is not a dye, stain or paint, but causes a chemical reaction with the amino acids in the dead layer on the skin surface. One of the pathways is a free radical-mediated Maillard reaction. The other pathway is the conventional Maillard reaction, a process well known to food chemists that causes the browning that occurs during food manufacturing and storage. It does not involve the underlying skin pigmentation nor does it require exposure to ultraviolet light to initiate the color change. However, for the 24 hours after self-tanner is applied, the skin is especially susceptible to ultraviolet, according to a 2007 study led by Katinka Jung of the Gematria Test Lab in Berlin. Forty minutes after the researchers treated skin samples with high levels of DHA they found that more than 180 percent additional free radicals formed during sun exposure compared with untreated skin. Another self-tanner ingredient, erythrulose, produced a similar response at high levels. For a day after self-tanner application, excessive sun exposure should be avoided and sunscreen should be worn outdoors, they say; an antioxidant cream could also minimize free radical production. Although some self-tanners contain sunscreen, its effect will not last long after application, and a fake tan itself will not protect the skin from UV exposure. The study by Jung et al. further confirms earlier results demonstrating that dihydroxyacetone in combination with dimethylisosorbide enhances the process of (sun-based) tanning.
=== 1994–1999: The Double Trio, Vrooom, Thrak and the ProjeKcts === In the summer of 1991, Belew met with Fripp in England to express an interest in reviving King Crimson. That year saw the release of the retrospective box set Frame by Frame: The Essential King Crimson. A follow-up box set, The Great Deceiver, appeared the following year as the first release on Fripp's newly-established record label Discipline Global Mobile (DGM), formed with producer David Singleton. Subsequently, DGM would be the primary home for Fripp's work, with larger album releases distributed to bigger record companies (initially Virgin Records), and smaller releases handled by DGM. This afforded Fripp and his associates greater creative freedom and more control over all aspects of their work.
Sources: en.wikipedia.org
==== Reward circuitry ==== NOP is highly expressed in every node of the mesocorticolimbic reward circuitry. Unlike MOP agonists such as codeine and morphine, NOP agonists do not have reinforcing effects. Nociceptin is thought to be an endogenous antagonist of dopamine transport that may act either directly on dopamine or by inhibiting GABA to affect dopamine levels. In animal models, the result of NOP activation in the central nervous system has been shown to eliminate conditioned place preference induced by morphine, cocaine, alcohol, and methamphetamine.
In 1887 Johannes Wislicenus published a study of stereoisomerism in unsaturated compounds. Groth made a systematic classification of minerals based on their chemical composition and crystal structure and published his results in his 5-volume Chemische Kristallographie in 1906–1919, which contained crystalline morphology and physical property data on nearly 10,000 substances. In 1913 Walter Wahl summarised the known connections between chemical composition and crystalline form as isomorphism (Mitscherlich), morphotropism (Groth), and enantiomorphism (Pasteur and van 't Hoff). In his preface to Andreas Fock's An introduction to chemical crystallography Pope summarised the state of chemical crystallography in 1895 as follows:
Russian launched around 81 missiles, including 6 kinzhal missiles and 8 drones at Ukrainian cities. Ukraine's Military stated it shot down 34 missiles and 4 Shahed drones. Around nine people were killed and blackouts were reported. The Zaporizhzhia Nuclear Power Plant was briefly cut off from the Ukrainian electrical grid, leaving it running on backup diesel generators for the sixth time since Russian forces seized control of it 12 months ago. Russia stated that the attack was response to the 2023 Bryansk Oblast attack. The Head of Lithuanian military intelligence Elegijus Paulavicius, said in an interview that Russia had the resources to continue the war in Ukraine for at least two years at the "current intensity". He also dismissed the effect of sanctions as Russia had "long chains of intermediaries" to obtain Western technology. Western officials estimated between 20,000 and 30,000 Russian soldiers had been killed or wounded in the fighting around Bakhmut, while Ukrainian forces have lost about one fifth as many. These numbers could not be verified.
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.
It acts on the growth hormone-releasing hormone receptor found on pituitary somatotroph cells. Activation of that receptor triggers growth hormone release through a cyclic AMP dependent pathway.