LC-MS/MS raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-01-06. Anything still debated is marked as such rather than presented as settled.
The fragment includes residues that can form an internal disulfide bond between two cysteine positions. This structural feature can influence how the peptide folds and how stable it is in solution. AOD-9604 differs from full-length hGH in size and receptor interactions; it does not contain the entire growth hormone sequence. Published descriptions sometimes use slightly different residue numbering, so sequence information should be checked against primary sources. The molecule is small compared with intact hGH, which affects analytical detection and purification approaches.
Interest in AOD-9604 arose from attempts to separate metabolic effects from growth effects attributed to hGH. Early work explored whether the fragment could influence lipolysis or fat oxidation without promoting growth. Those questions remain partly unresolved because human data are limited and results have varied across studies. The peptide is not a hormone replacement for hGH and is not equivalent to hGH in clinical use. Its research history includes both laboratory studies and commercial marketing claims that are not the same as regulatory approval.
AOD-9604 has been investigated mainly in the context of body fat and metabolic endpoints. Some early animal and small human studies reported changes in fat mass or lipid markers, but findings were not uniform. Larger, well-controlled trials that would establish efficacy are lacking in the public literature. As a result, claims about weight loss or metabolic benefit remain investigational rather than established. The distinction between a research finding and a proven clinical outcome is central to discussing this peptide.
Regulatory bodies have taken different approaches to AOD-9604. It is not approved as a prescription medicine by major agencies such as the U.S. Food and Drug Administration or the European Medicines Agency. In sport, the World Anti-Doping Agency prohibits peptide hormones, growth factors, and related substances, and AOD-9604 has been treated as a prohibited substance. These regulatory decisions reflect concerns about safety, efficacy, and potential misuse rather than proof of benefit.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | Based on the C-terminal region of human growth hormone. |
| Amino acid length | 16 residues | Often described as hGH fragment 176-191. |
| Appearance | Lyophilized powder | Typically white to off-white; exact appearance depends on grade. |
| Solubility | Soluble in water | Aqueous solubility depends on pH, ionic strength, and preparation. |
| Typical storage | -20 °C or lower | Lyophilized peptide is usually kept cold and dry; solutions may require freezing. |
AOD-9604 is listed as a prohibited substance in sport by the World Anti-Doping Agency. It falls under the peptide hormones, growth factors, related substances, and mimetics class on the prohibited list. Anti-doping organizations treat its presence in an athlete's sample as an adverse finding unless a therapeutic use exemption applies. The prohibition reflects concerns about performance enhancement in competitive settings and the difficulty of distinguishing exogenous peptide use from endogenous hormone fragments.
Detection of AOD-9604 in biological samples relies on analytical techniques capable of distinguishing a small synthetic peptide from related endogenous sequences. Liquid chromatography coupled with tandem mass spectrometry is commonly used for confirmatory analysis. Sample preparation may involve immunoaffinity enrichment or solid-phase extraction to concentrate the peptide. Because the molecule is small and may be present at low concentrations, assay sensitivity and specificity are ongoing analytical challenges. Laboratories also validate methods against reference materials when available.
Regulatory interest in AOD-9604 increased after high-profile anti-doping cases involving peptide products. In some cases, the substance was supplied under alternative names or in compounded preparations, complicating traceability. Sports tribunals and anti-doping panels have discussed whether the peptide was explicitly banned at the time of use, leading to clarifications by the World Anti-Doping Agency. For consumers and researchers, the legal status can vary by jurisdiction, and products marketed as research chemicals may lack independent quality verification.
AOD-9604 is a synthetic peptide that corresponds to a short section of human growth hormone. It is commonly identified as hGH fragment 176-191 because its sequence matches residues at the C-terminal end of the hormone. The molecule contains sixteen amino acids and is made by solid-phase peptide synthesis. Researchers study it for metabolic effects rather than for the growth-promoting actions associated with full human growth hormone. Its small size distinguishes it from the complete 191-amino-acid hormone.
Several names appear in scientific and commercial settings. AOD9604 and AOD-9604 are development codes used interchangeably, while hGH fragment 176-191 describes the same region. The peptide includes a disulfide bond between two cysteine residues, which helps shape its three-dimensional structure. Different suppliers may provide acetate or other salt forms, and purity can vary. These differences matter because analytical tests and biological assays can respond to the specific form being studied.
Proposed mechanisms for AOD-9604 focus on fat cells. Laboratory studies suggest the peptide can increase lipolysis, the breakdown of stored fat, and reduce lipogenesis, the formation of new fat. Unlike full human growth hormone, it does not appear to stimulate substantial IGF-1 production in the studies reported so far. Some evidence points to beta-adrenergic signaling, but the precise receptor targets and downstream pathways remain unresolved. The fragment is not thought to act through the classical growth hormone receptor.
Clinical development of AOD-9604 included trials in people with obesity. Reports from early-phase and mid-phase studies described modest or inconsistent changes in body weight. A phase IIb program did not meet its primary endpoint, and the compound was not approved for medical use. Differences in formulation, delivery route, and participant characteristics may explain some of the variation. Later investigations explored whether the peptide might have effects in other tissues, including cartilage.
=== Gina Cross === Dr. Gina Cross (voiced by Kathy Levin) is a Black Mesa scientist who first appears as the Holographic Assistant for Gordon Freeman in the Black Mesa's Hazard Course and then later as one half of the protagonists in Half-Life: Decay. In Decay, Cross is the one who delivers the GG-3883 crystal sample to the delivery system and then heads to an area below the test chamber, where Dr. Colette Green is stationed, to fix a jam in the lift that allows the specimen to be delivered up to Gordon. After the Resonance Cascade occurs, Cross teams up with Dr. Green to battle their way through the now alien-infested facility. They first escort Rosenberg to the surface to contact the military, and then under the guidance of Dr. Richard Keller, they succeed in starting a resonance reversal to help lessen the effects of the dimensional rift. In Half-Life: Blue Shift, Cross can briefly be seen on a security camera in the surveillance room, delivering the GG-3883 crystal. In Half-Life: Opposing Force, Adrian Shephard finds Cross's corpse in Xen after being teleported there by the Displacer Cannon, which implies that she died sometime after the events of Decay. Randy Pitchford, the president and CEO of Gearbox Software, had since confirmed this fate. However, Valve themselves never confirmed anything about Cross's fate after the events of Decay. Cross was originally planned to be Gordon Freeman's spouse as well as another playable character in the original Half-Life, but this idea was cut from the final game.
) as a crystal and powder. The signal observed, called the Pake doublet, was from the magnetically active hydrogens in water. Pake then calculated the proton-proton bond length. NMR measurements were further revolutionized when commercial machines became available in the 1960s. Before this, NMR experiments involved constructing massive projects, locating large magnets, and hand wiring miles of copper coil. Proton NMR remained the most popular technique throughout advancements in following decades, but 2H and 3H were used in other flavors of NMR spectroscopy. 2H has a different magnetic moment and spin than 1H, but generally a much smaller signal. Historically, deuterium NMR is a poor alternative to proton NMR, but has been used to study the behavior of lipids on cell membranes. A variant of 2H NMR called 2H-SNIF has shown potential for understating position-specific isotope compositions and comprehending biosynthetic pathways. Tritium is also used in NMR, as it is the only nucleus more sensitive than 1H, generating very large signals. However, tritium's radioactivity discouraged many studies of 3H-NMR. While tritium's radioactivity discourages use in spectroscopy, tritium is essential for nuclear weapons. Scientists began understanding nuclear energy as early as the 1800s, but large advancements were made in studies of the atomic bomb in the early 1940s. Wartime research, especially the Manhattan Project, greatly advanced the understanding of radioactivity. 3H is a byproduct in reactors, a result of hitting lithium-6 with neutrons, producing almost 5 MeV of energy.
== External links == Large+Neutral+Amino+Acid-Transporter+1 at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Amino+Acid+Transport+System+L at the U.S. National Library of Medicine Medical Subject Headings (MeSH) This article incorporates text from the United States National Library of Medicine, which is in the public domain.
Sources: en.wikipedia.org
With the 100:1 ratio, conviction in federal court for possession of 5 grams of crack would receive the same 5-year mandatory minimum as possession of 500 grams of powder cocaine. Debate at the time considered whether crack, generally used by blacks, was more addictive than the powder form, generally used by whites, comparing the effects of snorting powder cocaine with the briefer, more intense high from smoking crack; pharmacologically, there is no difference between the two. According to the DEA, at first crack "was not fully appreciated as a major threat because it was primarily being consumed by middle class users who were not associated with cocaine addicts ... However, partly because crack sold for as little as $5 a rock, it ultimately spread to less affluent neighborhoods." Support for Reagan's drug crime legislation was bipartisan. According to historian Hinton, Democrats supported drug legislation as they had since the Johnson administration, though Reagan was a Republican. Internationally, the Reagan term saw a huge increase in US military anti-drug activity in other countries. The Department of Defense budget for interdiction increased from $4.9 million in 1982 to $397 million by 1987. The DEA also expanded its foreign presence. Countries were encouraged to adopt the same type of punitive drug approach that was in place in the US, with the threat of economic sanctions for non-compliance.
== External links == Atrial+Natriuretic+Factor at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Human NPPA genome location and NPPA gene details page in the UCSC Genome Browser. Overview of all the structural information available in the PDB for UniProt: P01160 (Natriuretic peptides A) at the PDBe-KB.
Essentially, these specialized reticular cells form pathways that guide T cells deeper into cancer tissue, improving immune responses and tumor regulation in the body. The findings suggest that reticular cells, previously thought to be limited to only lymphoid tissues, can reform immune environments within tumors. This opens many new possibilities for cancer treatment in the world of medicine. Moreover, reticular cells help balance immune activation and tolerance. By regulating cytokine and antigen accessibility, they prevent excessive immune responses in cells that could actually damage host tissues. Through these methods, they act as immune regulators, ensuring that the body initiates very strong defenses against pathogens while minimizing potential damage. The emerging evidence recognizes reticular cells as a potential important factor of disease regulation connecting immunity to tissue repair and inflammation control in the body.
Sources: en.wikipedia.org
It is a synthetic peptide based on a C-terminal fragment of human growth hormone. It is commonly referred to as hGH fragment 176-191 and is studied for metabolic effects rather than growth effects.
No. It represents only a short portion of the hGH sequence and lacks the full hormone's structure. As a result, its biological activity and regulatory status differ from those of prescription hGH.
The exact peptide is not typically described as a circulating hormone; it is a synthetic construct based on a natural sequence. Fragments of hGH can exist in laboratory or metabolic contexts, but AOD-9604 itself is manufactured for research.
No. It is not approved as a therapeutic drug by major regulators. It is sold for research purposes in many settings, which is not the same as clinical approval.