A practical reference on mass spectrometry: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-08 and is reviewed periodically as new material appears.
Four amino acid substitutions separate the modified backbone from the parent GRF(1-29) sequence. These changes reduce recognition by dipeptidyl peptidase IV and related proteases, extending the interval before degradation. Development work in this area sought longer-acting GHRH analogs for endocrine investigation. Published descriptions treat the substitution set as a defining property of the core sequence, while the albumin-binding linker is described separately as an optional addition to that same backbone.
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.
Receptor level activity follows the canonical GHRH pathway. The peptide binds the GHRH receptor, a class B G protein coupled receptor on somatotroph cells of the anterior pituitary. Binding raises intracellular cyclic AMP, which promotes calcium entry and the release of growth hormone into the bloodstream. Because the molecule acts at the same receptor as the endogenous hormone, its effect is superimposed on the natural pulsatile rhythm rather than replacing it. Whether sustained receptor occupation leads to desensitization is not fully settled.
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.
| 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 |
Pharmacokinetic behaviour differs sharply between the two forms. The DAC-bearing peptide shows an extended circulation time measured in days, whereas the version without the complex is cleared within roughly half an hour. This gap shapes how researchers design dosing schedules in animal models. Whether the prolonged presence of the DAC form produces effects meaningfully different from the short-acting variant remains an open question, since comparative human data are scarce.
CJC-1295 is a synthetic peptide designed to mimic growth hormone-releasing hormone (GHRH), the endogenous signal that prompts the pituitary gland to release growth hormone. The compound is a modified fragment of the natural hormone, spanning the first twenty-nine amino acids of GHRH with several substitutions that slow enzymatic breakdown. Two variants circulate in research settings: one carrying a drug affinity complex (DAC) and one without it. The DAC-free form is frequently labelled Mod GRF(1-29) in catalogs and discussion forums.
The peptide binds GHRH receptors on somatotroph cells within the anterior pituitary, triggering a signalling cascade that increases growth hormone secretion. Its improved resistance to dipeptidyl peptidase IV degradation distinguishes it from the parent hormone. In the DAC-bearing version, a maleimide group reacts with a cysteine residue on serum albumin, forming a covalent bond that keeps the peptide in circulation far longer. That albumin attachment is the central design feature separating the two research variants.
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.
Reported half-lives differ widely between the two variants and between species. Values for the albumin-binding form are usually expressed in days, while the unconjugated form is measured in minutes to a few hours. Sampling schedules, assay sensitivity, and route of administration all influence the numbers, which limits direct comparison across studies. Whether sustained receptor occupancy produces different downstream effects from pulsatile stimulation remains an open question in the published work. Claims about relative potency should therefore be read alongside the specific study design that produced them.
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.
== History == In ancient history, Hippocrates discussed bile pigments in two of the four humours in the context of a relationship between yellow and black biles. Hippocrates visited Democritus in Abdera who was regarded as the expert in melancholy "black bile". Relevant documentation emerged in 1827 when M. Louis Jacques Thénard examined the biliary tract of an elephant that had died at a Paris zoo. He observed dilated bile ducts were full of yellow magma, which he isolated and found to be insoluble in water. Treating the yellow pigment with hydrochloric acid produced a strong green color. Thenard suspected the green pigment was caused by impurities derived from mucus of bile. Leopold Gmelin experimented with nitric acid in 1826 to establish the redox behavior in change from bilirubin to biliverdin, although the nomenclature did not exist at the time. The term biliverdin was coined by Jöns Jacob Berzelius in 1840, although he preferred "bilifulvin" (yellow/red) over "bilirubin" (red). The term "bilirubin" was thought to have become mainstream based on the works of Staedeler in 1864 who crystallized bilirubin from cattle gallstones. Rudolf Virchow in 1847 recognized hematoidin to be identical to bilirubin.
The concept of functional groups is central in organic chemistry, both as a means to classify structures and for predicting properties. A functional group is a molecular module, and the reactivity of that functional group is assumed, within limits, to be the same in a variety of molecules. Functional groups can have a decisive influence on the chemical and physical properties of organic compounds. Molecules are classified based on their functional groups. Alcohols, for example, all have the subunit C-O-H. All alcohols tend to be somewhat hydrophilic, usually form esters, and usually can be converted to the corresponding halides. Most functional groups feature heteroatoms (atoms other than C and H). Organic compounds are classified according to functional groups, e.g., alcohols, carboxylic acids, amines, etc. Functional groups make the molecule more acidic or basic due to their electronic influence on surrounding parts of the molecule. As the pKa (aka basicity) of the molecular addition/functional group increases, there is a corresponding dipole, when measured, increases in strength. A dipole directed towards the functional group (higher pKa therefore basic nature of group) points towards it and decreases in strength with increasing distance. Dipole distance (measured in Angstroms) and steric hindrance towards the functional group have an intermolecular and intramolecular effect on the surrounding environment and pH level.
Dihydrocodeine, sold under the brand name Dicodin among others, is a semi-synthetic opioid analgesic prescribed for pain or severe dyspnea, or as an antitussive, either alone or compounded with paracetamol (acetaminophen) (as in co-dydramol) or aspirin. It was developed in Germany in 1908 and first marketed in 1911. Commonly available as tablets, solutions, elixirs, and other oral forms, dihydrocodeine is also available in some countries as an injectable solution for deep subcutaneous and intra-muscular administration. As with codeine, intravenous administration should be avoided, as it could result in anaphylaxis and life-threatening pulmonary edema. In the past, dihydrocodeine suppositories were used. Dihydrocodeine is available in suppository form on prescription. Dihydrocodeine is used as an alternative to codeine and similarly belongs to step 2 of the WHO analgesic ladder. It was first described in 1911 and approved for medical use in 1948. Dihydrocodeine was developed during the search for more effective cough medication, especially to help reduce the spread of tuberculosis, pertussis, and pneumonia in the years from c.a. 1895 to 1915. It is similar in chemical structure to codeine.
=== Clearance === Met- and leu-enkephalin are metabolized by a variety of different enzymes, including aminopeptidase N (APN), neutral endopeptidase (NEP), dipeptidyl peptidase 3 (DPP3), carboxypeptidase A6 (CPA6), and angiotensin-converting enzyme (ACE). These enzymes are sometimes referred to as enkephalinases.
The discoverers also intended to reference the support of their research by the Japanese people (Riken being almost entirely government-funded), recover lost pride and trust in science among those who were affected by the Fukushima Daiichi nuclear disaster, and honour Japanese chemist Masataka Ogawa's 1908 discovery of rhenium, which he named "nipponium" with symbol Np after the other Japanese pronunciation of Japan's name. As Ogawa's claim had not been accepted, the name "nipponium" could not be reused for a new element, and its symbol Np had since been used for neptunium. In March 2016, Morita proposed the name "nihonium" to IUPAC, with the symbol Nh. The naming realised what had been a national dream in Japanese science ever since Ogawa's claim. The former president of IUPAP, Cecilia Jarlskog, complained at the Nobel Symposium on Superheavy Elements in Bäckaskog Castle, Sweden, in June 2016 about the lack of openness involved in the process of approving new elements, and stated that she believed that the JWP's work was flawed and should be redone by a new JWP. A survey of physicists determined that many felt that the Lund–GSI 2016 criticisms of the JWP report were well-founded, but it was also generally thought that the conclusions would hold up if the work was redone. Thus the new president, Bruce McKellar, ruled that the proposed names should be released in a joint IUPAP–IUPAC press release. IUPAC and IUPAP publicised the proposal of nihonium that June, and set a five-month term to collect comments, after which the name would be formally established at a conference.
Sources: en.wikipedia.org
== Clinical significance == Identification of the submucosa plays an important role in diagnostic and therapeutic endoscopy, where special fibre-optic cameras are used to perform procedures on the gastrointestinal tract. Abnormalities of the submucosa, such as gastrointestinal stromal tumors, usually show integrity of the mucosal surface. The submucosa is also identified in endoscopic ultrasound to identify the depth of tumours and to identify other abnormalities. An injection of dye, saline, or epinephrine into the submucosa is imperative in the safe removal of certain polyps. Endoscopic mucosal resection involves removal of the mucosal layer, and in order to be done safely, a submucosal injection of dye is performed to ensure integrity at the beginning of the procedure. Female uterine submucosal layers are liable to develop fibroids during pregnancy and are often excised upon discovery.
Nitrogen is the most common pure element in the earth, making up 78.1% of the volume of the atmosphere (75.5% by mass), around 3.89 million gigatonnes (3.89×1018 kg). Despite this, it is not very abundant in Earth's crust, making up somewhere around 19 parts per million of this, on par with niobium, gallium, and lithium. (This represents 300,000 to a million gigatonnes of nitrogen, depending on the mass of the crust.) The only important nitrogen minerals are nitre (potassium nitrate, saltpetre) and soda nitre (sodium nitrate, Chilean saltpetre). However, these have not been an important source of nitrates since the 1920s, when the industrial synthesis of ammonia and nitric acid became common. Nitrogen compounds constantly interchange between the atmosphere and living organisms. Nitrogen must first be processed, or "fixed", into a plant-usable form, usually ammonia. Some nitrogen fixation is done by lightning strikes producing the nitrogen oxides, but most is done by diazotrophic bacteria through enzymes known as nitrogenases (although today industrial nitrogen fixation to ammonia is also significant). When the ammonia is taken up by plants, it is used to synthesise proteins. These plants are then digested by animals who use the nitrogen compounds to synthesise their proteins and excrete nitrogen-bearing waste. Finally, these organisms die and decompose, undergoing bacterial and environmental oxidation and denitrification, returning free dinitrogen to the atmosphere.
=== Cuban Thaw and attempts to repair relationship === In 2011, Lazaro Cuesta Valdes was elected as the Grand Commander of the Supreme Council of Cuba. After his election, the Supreme Council created a Facebook page, launched an updated webpage, and launched the first International Conference on Freemasonry and Integration to Current Society. Between 2012 and 2014, Grand Commander Cuesta Valdes travelled around the world, first to Rome, and then to visit the Supreme Councils of the United States' Southern Jurisdiction and Northern Jurisdiction, in Ohio and Washington, D.C. Informally, he also met with leaders of the Cuban exile Freemasonry community in Miami to strengthen relations with the United States. In October 2013, the Supreme Council of Cuba held an open meeting and invited Cuban Masons living anywhere to Havana to discuss the fractured state of Cuban Freemasonry. Grand Master Gutierrez Torres attended and drafted Official Message No. 6 after discussions with members of the diaspora. In April 2014, while still in prison, Alan Gross launched a hunger strike to protest his treatment by both Cuba and the United States. When the Associated Press leaked the ZunZuneo program documents to the public, Senator Patrick Leahy called it: "Dumb, dumb, dumb." Leahy then led the Senate committee review of the debacle. On December 17, 2014, Alan Gross was released from Cuban prison in exchange for three members of the Cuban Five, who had been detained in the United States and charged with espionage. On December 10, 2016, the Lazaro F.
====== Pain medicine ====== To train in the add-on specialty of pain medicine a physician must first be a specialist in one of the pediatric class specialties, one of the independent class specialties (excluding clinical pharmacology, clinical genetics, forensic medicine, and social medicine), one of the internal medicine class specialties, one of the surgical class specialties, one of the neurological class specialties (excluding clinical neurophysiology) or one of the psychiatric class specialties.
Additionally, some clinically used drugs such as chlorpheniramine, dextromethorphan, and methadone possess SRI properties secondarily to their primary mechanism of action(s) and this contributes to their side effect and drug interaction profiles. A closely related type of drug is a serotonin releasing agent (SRA), an example of which is fenfluramine.
Sources: en.wikipedia.org
The retinoids are a class of chemical compounds consisting of vitamin A and related derivatives. Synthetic retinoids are utilized in cosmetic formulations, clinical dermatology, and the treatment of some forms of cancer. Retinoids have many important functions throughout the body, including in vision, regulation of skin proliferation and differentiation, growth of bone tissue, immune function, and male fertility. The biology of retinoids is complex, having well-documented effectiveness in the management of conditions ranging from acute promyelocytic leukemia to acne to photoaging. On the other hand, retinoids may be involved in metabolic dysfunction and, at least in some forms, carcinogenesis.
Politically, mercantilism was gradually replaced by liberal thoughts among the ruling elite. Following a monetary reform after the Napoleonic wars, the present Danish central bank Danmarks Nationalbank was founded in 1818. There exists national accounting data for Denmark from 1820 onwards thanks to the pioneering work of Danish economic historian Svend Aage Hansen. They find that there has been a substantial and permanent, though fluctuating, economic growth all the time since 1820. The period 1822–94 saw on average an annual growth in factor incomes of 2% (0.9% per capita) From around 1830 the agricultural sector experienced a major boom lasting several decades, producing and exporting grains, not least to Britain after 1846 when British grain import duties were abolished. When grain production became less profitable in the second half of the century, the Danish farmers made an impressive and uniquely successful change from vegetarian to animal production leading to a new boom period. Parallelly industrialization took off in Denmark from the 1870s. At the turn of the century industry (including artisanry) fed almost 30% of the population. During the 20th century agriculture slowly dwindled in importance relative to industry, but agricultural employment was only during the 1950s surpassed by industrial employment. The first half of the century was marked by the two world wars and the Great Depression during the 1930s.
1888: American chemist Josephine Silone Yates was appointed head of the Department of Natural Sciences at Lincoln Institute (later Lincoln University), becoming the first black woman to head a college science department. 1889: American astronomer Antonia Maury discovered the second spectroscopic binary, Beta Aurigae, and calculated its orbital period. 1889: American geologist Mary Emilie Holmes became the first female Fellow of the Geological Society of America.
Cammack R, Jackson RH, Cornish-Bowden A, Cole JA (1982). "Electron-spin-resonance studies of the NADH-dependent nitrite reductase from Escherichia coli K12". Biochem. J. 207 (2): 333–9. doi:10.1042/bj2070333. PMC 1153865. PMID 6297458. Lazzarini RA; Atkinson DE (1961). "A triphosphopyridine nucleotide-specific nitrite reductase from Escherichia coli". J. Biol. Chem. 236 (12): 3330–3335. doi:10.1016/S0021-9258(18)94019-6. PMID 14463130. Nicholas DJ, Medina A, Jones OT (1960). "A nitrite reductase from Neurospora crassa". Biochim. Biophys. Acta. 37 (3): 468–76. doi:10.1016/0006-3002(60)90503-5. PMID 14426899. Taniguchi H, Mitsui H, Nakamura K, Egami F. "Ann. Acad. Sci. Fenn. Ser. A II 60 (1955) 200". {{cite journal}}: Cite journal requires |journal= (help) Colandene JD, Garrett RH (1996). "Functional dissection and site-directed mutagenesis of the structural gene for NAD(P)H-nitrite reductase in Neurospora crassa". J. Biol. Chem. 271 (39): 24096–104. doi:10.1074/jbc.271.39.24096. PMID 8798648.
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.
The names are often used interchangeably in casual writing, but they are not strictly identical. Modified GRF(1-29) refers to the unconjugated analogue carrying only the four substitutions. The version sold as CJC-1295 with DAC includes the albumin binding linker and clears much more slowly.