This is a working overview of growth hormone, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-05-01 and is reviewed periodically as new material appears.
Signaling begins at the GHRH receptor, a class B G protein-coupled receptor displayed on somatotroph cells of the anterior pituitary. Receptor occupancy activates Gs proteins, which raise adenylyl cyclase activity and intracellular cyclic AMP, in turn driving protein kinase A dependent pathways. The downstream output is synthesis and pulsatile secretion of growth hormone into the bloodstream. Hepatic tissue and peripheral sites respond by increasing insulin-like growth factor 1 production. Somatostatin and IGF-1 itself supply negative feedback that caps the size and duration of each secretory burst.
Metabolic interest in this compound centers on fat distribution rather than on hormone levels alone. Imaging trials in adults with excess abdominal fat report reductions in visceral adipose tissue, while subcutaneous depots change comparatively little. Growth hormone and IGF-1 are presumed to carry the effect, but the separate contribution of each is not firmly established. Whether these changes persist after treatment stops, and whether they alter longer-term health outcomes, remain open questions that published work does not answer consistently.
Tesamorelin is a synthetic peptide of forty-four amino acids whose sequence reproduces human growth hormone-releasing hormone. Its distinguishing feature sits at the amino terminus, where a trans-3-hexenoyl group replaces the free amine. That acylation slows cleavage by dipeptidyl peptidase IV, an enzyme that otherwise removes the first two residues and inactivates the natural hormone quickly. The modified peptide therefore persists longer in circulation while keeping the same receptor target. It is handled as a lyophilized solid and dissolved shortly before use.
Clinical study of tesamorelin has centered on adults with HIV-associated lipodystrophy, a condition in which abdominal fat accumulates while peripheral fat is lost. In controlled trials, treated participants showed reductions in visceral adipose tissue measured by imaging, alongside modest shifts in some lipid values. Effects on subcutaneous fat were smaller and less consistent across studies. Whether these changes translate into fewer cardiovascular events remains an open question, because the trials were not designed or powered to answer it.
Tesamorelin is a synthetic peptide that acts as an analog of growth hormone-releasing hormone, a natural hypothalamic signal. Its sequence corresponds to the forty-four amino acid form of the human hormone, with a small acyl group attached near the amino terminus. That modification slows enzymatic breakdown and extends the time the peptide remains active in circulation. The compound was developed as a pharmacological way to raise endogenous growth hormone output rather than supplying the hormone directly.
After injection, the peptide binds receptors on somatotroph cells in the anterior pituitary. Receptor activation raises intracellular cyclic AMP and triggers release of stored growth hormone into the bloodstream. Because the compound works through the body's own regulatory system, growth hormone pulses retain much of their normal feedback control. Repeated administration also raises insulin-like growth factor 1, a hormone produced mainly in the liver. Investigators treat that rise as a marker that the pituitary axis has been engaged.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic 44-residue peptide | GHRH analog backbone |
| Approximate molecular mass | 5136 Da | Varies with counterion and hydration state |
| N-terminal group | trans-3-hexenoyl | Increases resistance to dipeptidyl peptidase IV |
| Primary receptor | GHRH receptor (GHRHR) | Class B G protein-coupled receptor on somatotrophs |
| Principal mediator | IGF-1 | Rises indirectly after growth hormone release |
Tesamorelin binds to growth hormone-releasing hormone receptors on the surface of pituitary somatotroph cells. This binding activates adenylate cyclase, raising intracellular cyclic AMP levels and triggering the release of growth hormone into circulation. The elevated growth hormone then stimulates hepatic production of insulin-like growth factor 1. Because the effect is mediated through the endogenous axis, secretion remains subject to feedback regulation. This distinguishes it from direct growth hormone administration, which bypasses pituitary control entirely.
Clinical investigation has focused on HIV-associated lipodystrophy, a condition in which antiretroviral therapy contributes to abnormal fat distribution. Excess visceral adipose tissue accumulates in the abdomen while peripheral fat may be lost. Tesamorelin was evaluated for reducing this visceral fat depot, with trials measuring changes in abdominal fat by imaging rather than by body weight alone. The rationale rests on the known lipolytic effects of growth hormone. Effects on visceral fat are documented, while long-term outcomes regarding cardiovascular risk remain less clearly established.
Several related peptides act on the same receptor, including sermorelin, a shorter GHRH fragment, and modified analogs such as CJC-1295 and modified GRF(1-29) that are common in research settings rather than approved products. Tesamorelin differs from growth hormone itself in that it acts upstream, prompting the pituitary to release the hormone through physiological signaling rather than supplying it directly. Terminology in the literature distinguishes GHRH analogs, growth hormone secretagogues, and recombinant growth hormone, although popular discussion often blurs these categories together. Precise naming matters when comparing study results.
Tesamorelin is a synthetic peptide of 44 amino acids that reproduces the sequence of human growth hormone-releasing hormone (GHRH) and carries a trans-3-hexenoyl group on its N-terminal tyrosine. That small fatty-acid modification blocks cleavage by dipeptidyl peptidase-4, the enzyme that rapidly degrades native GHRH in plasma. The result is a molecule with a longer circulating half-life than the natural hormone while retaining the same receptor target. It is supplied as a lyophilized powder for reconstitution and belongs to the broader class of GHRH analogs studied for effects on pituitary growth hormone secretion.
Regulatory approval in the United States came in 2010, when the Food and Drug Administration cleared the peptide for the reduction of excess abdominal fat in adults with HIV infection and associated lipodystrophy. The decision rested mainly on two randomized phase 3 trials that enrolled roughly eight hundred patients and ran for twenty-six weeks. Participants receiving active drug showed substantially greater declines in visceral adipose tissue than those receiving placebo, while total body weight changed comparatively little. A reformulated presentation was later approved, and the product has remained a niche therapy rather than a general weight-loss agent.
Tesamorelin occupies a narrow position among agents that act on the growth hormone axis. Unlike growth hormone itself, which is given as replacement, it stimulates the pituitary to release the hormone in pulses, so the downstream increase in insulin-like growth factor 1 depends on intact somatotroph function. Other peptides in the same family include shorter GHRH fragments and synthetic secretagogues with different stability profiles. Several points remain unresolved, including whether the reduction in visceral fat translates into fewer cardiovascular events, what happens to metabolic markers after long-term use, and how the drug compares with lifestyle or surgical approaches.
== Physiology and biochemistry == Streptococcus pneumoniae is one of the mostly highly studied bacterial species containing CSP, though other genus and species also utilize the hormone-like protein. Variations in structure, receptor specificity, and codon sequence occur even between different strains of the same species. However, homology between CSP's retain a single negatively charged N-terminus, an arginine residue in position three (C3), and a positively charged C-terminus. Signal-receptor specificity is demonstrated in Streptococcal species through the relationship between CSP1 and CSP2 signals, and the receptors ComD1 and ComD2. Variations of receptor specificity and composition can be estimated based on nuclear magnetic resonance (NMR) spectroscopy analysis. Alterations in the structure of CSP signals, such as CSP1 and CSP2, are shown to inhibit the cellular response to these peptides, often resulting in reduced biofilm production. Replacement of the first glutamate residue in CSP1 inhibits receptor activation of competency genes, and hydrophobic regions on the CSP1 molecule play key roles in effective ComD1 and Com2 binding. Interspecies interactions between biofilm producing organisms induce the release of chemical signals that inhibit binding or receptor activation in competence stimulating processes. Initiation of DNA transformation begins as a threshold concentration of CSP is met within a bacterial cell. Cellular density is proportional to CSP concentration.
=== Beyond sequence similarity === Proteins are known to conserve their tertiary structure more strongly than their amino acid sequences. Two distantly related proteins can have minimal or even undetectable sequence similarity, yet have highly similar folds that can be compared via structural alignment. Examples of these proteins used to be only discovered by experimental structural determination methods. Modern protein structure prediction methods such as AlphaFold2 allow possible homologs to be identified without wet lab work. RNA is also known to conserve tertiary structure more strongly than primary structure. RNA secondary structure prediction was found to be helpful in human-to-mouse comparison.
== Molecular studies == A monophyletic Pancrustacea has been supported by several molecular studies, in most of which the subphylum Crustacea is paraphyletic with regard to hexapods (that is, that hexapods, including insects, are derived from crustacean ancestors). This means that within Pancrustacea, only some members are actually crustaceans, hexapods being the main exception. The evidence for this clade derives from molecular data and morphological characteristics. The molecular data consists of comparisons of nuclear ribosomal RNA genes, mitochondrial ribosomal RNA genes, and protein coding genes. The morphological data consists of ommatidial structures (see arthropod eye), the presence of neuroblasts, and the form and style of axonogenesis by pioneer neurons.
Cited half-life: the median age of the articles that were cited in Journal Citation Reports each year. For example, if a journal's half-life in 2005 is 5, that means the citations from 2001 to 2005 are half of all the citations from that journal in 2005, and the other half of the citations precede 2001. Aggregate impact factor for a subject category: it is calculated taking into account the number of citations to all journals in the subject category and the number of articles from all the journals in the subject category. Immediacy index: the number of citations the articles in a journal receive in a given year divided by the number of articles published. Journal citation indicator (JCI): a JIF that adjusts for scientific field; it is similar to Source Normalized Impact per Paper, calculated based on the Scopus database. JCI is available for all journals in the Web of Science Core Collection (WoS CC)—including the AHCI, ESCI, BCI, CPCI—while JIF is only available for the SCIE and SSCI; however, starting in June 2023, JIF will also be issued for all journals in the WoS CC. JIF quartile ranking: a rank based on the four quartiles within a given subject or topic category. JIF percentile ranking: a percentile rank computed for a particular subject category. A given journal may attain a different quartile or percentile in different categories. As with the impact factor, there are some nuances to this: for example, Clarivate excludes certain article types (such as news items, correspondence, and errata) from the denominator.
Topical estradiol gel at a dosage of 3 mg/day has been reported to be equipotent with 2 mg oral estradiol in terms of therapeutic effects and FSH suppression, as well as to produce similar estradiol levels. Transdermal estradiol gel produces an estradiol to estrone ratio of about 1:1. Transdermal estradiol gel can be used as a form of high-dose estrogen in transgender women. However, the doses needed require application to a large surface of skin that amounts to the combined area of both legs for proper absorption. As a result, high-dose transdermal estradiol gel is not a primary choice of estrogen therapy for most transgender individuals. Similarly to transdermal estradiol patches, high-dose transdermal estradiol gel has been studied in the treatment of prostate cancer as well. In these studies, levels of estradiol with estradiol gel or ointment were 84 pg/mL with 3 mg/day, 185 pg/mL with 6 mg/day, 107 pg/mL with 10 mg/day, and 473 pg/mL with 20 mg/day. In women, high doses of estradiol gel, including 3 mg/day, 4 mg/day, and 8 mg/day, have been reported to produce estradiol levels of 99 pg/mL, 117 pg/mL, and 204 pg/mL, respectively. Studies have found that topical application of estradiol to the breasts increases local levels of estradiol in breast tissue. The total endometrial proliferation dose of transdermal estradiol gel in women has been reported to be 150 mg per cycle or 14 days. However, it has also been found that 6 mg/day estradiol gel is effective for endometrial proliferation in women.
Sources: en.wikipedia.org
==== Comparing PAM and BLOSUM ==== In addition to BLOSUM matrices, a previously developed scoring matrix can be used. This is known as a PAM. The two result in the same scoring outcome, but use differing methodologies. BLOSUM looks directly at mutations in motifs of related sequences while PAM's extrapolate evolutionary information based on closely related sequences. Since both PAM and BLOSUM are different methods for showing the same scoring information, the two can be compared but due to the very different method of obtaining this score, a PAM100 does not equal a BLOSUM100.
==== Niche uses ==== There are thousands of uses of various potassium compounds. One example is potassium superoxide, KO2, an orange solid that acts as a portable source of oxygen and a carbon dioxide absorber. It is widely used in respiration systems in mines, submarines and spacecraft as it takes less volume than the gaseous oxygen.
== Applications == LPC was first suggested as a human food in the early 20th century, but it has not achieved much success, despite early promise. Norman Pirie, the Copley Medal winner from the UK, studied LPC and promoted its use for human consumption. He and his team developed machines for extraction of LPC, including low-maintenance "village units" intended for poor rural communities. These were installed in places such as villages in south India. The non profit organization, Leaf for Life, maintains a list of human edible leaves and provides recommendations for the top choices of plants. There has recently been an interest in using LPCs as an alternative food (or resilient food) during times of catastrophe or food shortages. Such resilient food LPCs would be derived from widely geographically dispersed tree leaves from forests or agricultural waste. LPC have been evaluated for infant weaning foods. The increasing reliance on feedlot based animal rearing to satisfy human appetites for meat has increased demand for cheaper vegetable protein sources. This has recently led to renewed interest in LPC to reduce the use of human-edible vegetable protein sources in animal feed. Leaf protein has had successful trials as a substitute for soy feed for chickens and pigs. LPC from alfalfa can be included in feed for tilapia as a partial replacement for fish meal.
== Indications/Symptoms == Typical symptoms after being bitten by a black mamba include the rapid onset of dizziness, drowsiness and coughing and having difficulties breathing. Other likely symptoms include convulsions, neuromuscular symptoms, shock, loss of consciousness, hypotension, ataxia, excessive salivation, limb paralysis, nausea and vomiting, fever, and severe abdominal pain. Permanent limb paralysis is very likely if the bite remains untreated. In the most severe case, if untreated, the bite of the black mamba can lead to death by suffocation, resulting from the paralysis of respiratory muscles. All these symptoms are due to a combination of all the toxic peptides the crude venom of the black mamba contains. The symptoms are related to calciseptine because it also works as a smooth muscle relaxant, thus explaining the early onset of having difficulties breathing, limb paralysis and even death by suffocation. Calciseptine is known to have a hypotensive effect. It cannot clearly be established which peptide is most responsible for which symptom, since combinations of different toxins can have various effects.
Sources: en.wikipedia.org
is the radius of curvature of the menisci at the elongated ends of the droplet. This process is simple and consistently results in two droplets of equal volume. The conventional method of splitting an existing droplet by simply turning the splitting electrodes on and off produces new droplets of relatively equal volume. However, the new droplets formed by the conventional method show considerable difference in volume. This difference is caused by local perturbations due to the rapid mass transport. Even though the difference is negligible in some applications, it can still pose a problem in applications that are highly sensitive to variations in volume, such as immunoassays and DNA amplification. To overcome the limitation of the conventional method, an existing droplet can be split by gradually changing the potential of the electrodes at the splitting region instead of simply switching them on and off. Using this method, a noticeable improvement in droplet volume variation, from around 10% variation in volume to less than 1% variation in volume, has been reported.
=== Frabelle Fishing Corporation === Tiu Laurel became the president of the Frabelle Fishing Corporation in 1985 and its director in 2010. The family-owned business, which was established by Tiu Laurel's parents in 1966, is engaged in a variety of business interests in the agricultural and fisheries industry, such as deep-sea fishing, aquaculture, canning, meat and seafood processing, cold-chain network, shipbuilding and repair, and power generation. Frabelle operates in the Asia-Pacific region and supplies domestically in the Philippines and internationally. Concurrently, Tiu Laurel served as President of the Confederation of the Philippine Tuna Industry from 2002 to 2006, director of the Interland Deep Sea Fishing Sector, director of the World Tuna Purse Seine Organization, and chairman of the Processing Sector of Bangus (Milkfish) Council of the Philippines.
Frittola (frittula in Palermitan dialect) is a traditional Sicilian street food from the Palermo region of Italy. It is similar to the frittole from Reggio Calabria, but seems to use calf parts instead of pig. The waste left from the slaughter of mechanically processed calves includes bones that are ground for industrial use, and pieces of meat boiled at high temperature in large silos. After the meat is cooked it is pressed to remove moisture and formed into bales. This process, similar to lyophilization (freeze drying), can preserve the frittoli for years. The frittularu "revives" the frittoli by frying it with lard and placing it in a large wicker basket (the panaru) and a cloth of flavorings such as bay leaf, and pepper. It is served by hand and placed on a sheet of waxed paper or in a bun or focaccia. Frittola was once transported by donkey, but is now sold from three-wheeled vans. One author describes the dish as "oil fried fat and cartilage". An 1869 book reports frittola in Venice, although this most likely refers to a sweet or savoury fried dough rather than the meaty version from Palermo.
=== Benzene toxicity === Benzene poisoning can increase risk of hematological cancers and other disorders. The mechanism of benzene metabolism and how it affects toxicity has not been completely understood. A general observation is that there is high variation in the extent of damage due to benzene poisoning. A possible explanation is the accumulation of phenols and hydroquinone in the target organ—the bone marrow—and subsequent oxidation of these metabolites to reactive quinone metabolites via a number of possible pathways. A case-control study conducted in China showed that patients with two copies of the NQO1 C609T (NQO1*2 polymorphism) mutation had a 7.6-fold increased risk of benzene poisoning compared to those who carried one or two wild-type NQO1 alleles.
NMR spectroscopy is nucleus specific. Thus, it can distinguish between hydrogen and deuterium. The amide protons in the protein exchange readily with the solvent, and, if the solvent contains a different isotope, typically deuterium, the reaction can be monitored by NMR spectroscopy. How rapidly a given amide exchanges reflects its solvent accessibility. Thus amide exchange rates can give information on which parts of the protein are buried, hydrogen-bonded, etc. A common application is to compare the exchange of a free form versus a complex. The amides that become protected in the complex, are assumed to be in the interaction interface.
Sources: en.wikipedia.org
The amino acid sequence matches human growth hormone-releasing hormone, but the amino terminus carries a trans-3-hexenoyl group instead of a free amine. That single structural change chiefly affects enzymatic stability rather than receptor selectivity.
Growth hormone released from the pituitary stimulates IGF-1 production in the liver and other tissues, so circulating IGF-1 generally rises during exposure. The size of the rise varies between individuals and depends on baseline hormonal status and other concurrent factors.
Reported imaging studies focus on visceral adipose tissue, where reductions are more consistently observed across trials. Subcutaneous depots show smaller and less reproducible changes, so the two compartments should not be treated as equivalent.
It is a laboratory-made peptide that mimics growth hormone-releasing hormone. It prompts the pituitary gland to release growth hormone and has been studied mainly in adults with HIV-associated lipodystrophy.