This is a working overview of Dipeptidyl peptidase-4, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-08-26 and is reviewed periodically as new material appears.
Whether the drug improves hard clinical outcomes is not settled. No completed trial has shown a reduction in heart attacks or strokes among treated patients, although a dedicated cardiovascular outcomes study has been discussed in the literature. Investigators have also examined hepatic fat in people with HIV and fatty liver disease, cognitive measures in small cohorts, and changes in bone density. Regulatory labeling emphasizes monitoring of insulin-like growth factor 1 because supraphysiologic levels raise questions about tissue growth, and the clinical significance of that signal remains an open question rather than a demonstrated harm.
Binding of tesamorelin to the growth hormone-releasing hormone receptor on anterior pituitary somatotrophs activates a Gs protein pathway, raises cyclic AMP, and triggers release of stored growth hormone into the bloodstream. Because the analogue resists dipeptidyl peptidase-4, its plasma residence time exceeds that of native GHRH, producing a larger and more sustained secretory signal. The released growth hormone then acts on the liver and peripheral tissues to raise insulin-like growth factor 1, which feeds back on the hypothalamus and pituitary. This axis explains both the intended effects on fat distribution and the biological markers used to track them.
The native hormone is produced in the hypothalamus and acts on the anterior pituitary. Binding of GHRH to its receptor stimulates synthesis and release of growth hormone into circulation. Because the analogue retains the receptor-binding region of the parent sequence, it engages the same receptor and triggers the same downstream signaling. The result is increased growth hormone secretion from pituitary cells, which in turn influences hepatic production of insulin-like growth factor 1. This axis is the basis for the compound's measured biological effects.
Interest in this peptide developed because native GHRH has a short circulating lifetime. The N-terminal modification slows cleavage by dipeptidyl peptidase IV, an enzyme that removes the first two residues of many peptides and terminates their activity. Slower degradation means a longer window of receptor stimulation per administration. This design logic parallels other modified peptide hormones, where a small chemical change at a vulnerable site yields a more durable molecule without altering the core mechanism of action.
The peptide is synthesized chemically rather than extracted from biological sources. Solid-phase synthesis builds the chain from the C-terminus toward the N-terminus, after which the hexenoyl group is attached. Purity is typically assessed by high-performance liquid chromatography, and identity is confirmed by mass spectrometry. Regulatory review of the finished product focuses on these analytical controls, since small deviations in sequence or modification can change biological activity. Questions about long-term effects on the pituitary axis remain areas of continued investigation.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized cake in single-use vials |
| Solubility class | Freely soluble in water | Reconstituted with sterile diluent before injection |
| Typical storage temperature | 2 to 8 degrees Celsius | Before reconstitution; protect from light |
| Typical analytical method | Reversed-phase high-performance liquid chromatography | Purity and related-substance testing |
| Identity confirmation | Mass spectrometry | Observed mass near 5.1 kDa for the intact peptide |
Practical handling centers on limiting moisture, oxygen, and temperature excursions. Lyophilized material is generally held at or below minus twenty degrees Celsius, protected from light and kept sealed until use. Once reconstituted, solutions are typically kept cold and used within a short window because hydrolysis and microbial growth both accelerate in liquid form. Repeated freeze-thaw cycles are avoided, since they promote aggregation. Vial contents should be inspected for particulates and clarity before analysis, and working aliquots are prepared to reduce the number of times the stock is opened.
Quantitation of the peptide relies mainly on reversed-phase high-performance liquid chromatography with ultraviolet detection, typically at 214 nanometers, where the peptide bond absorbs. Identity is confirmed by mass spectrometry, most often electrospray ionization coupled to liquid chromatography, and by peptide mapping after enzymatic digestion. Because related impurities differ only slightly in sequence or modification, method development emphasizes resolution rather than speed. Purity is usually reported as a percentage of the main peak area, with individual impurities listed separately when they exceed a defined reporting threshold.
Stability testing examines how the molecule changes under controlled stress. Thermal stress, light exposure, and extremes of pH are applied separately so that each degradation route can be attributed to a specific cause. The main observed changes are oxidation, deamidation, and aggregation into dimers or higher-order species. Accelerated studies at elevated temperature are used to estimate behavior over longer periods, though such extrapolation carries uncertainty. For a lyophilized powder, residual moisture and the choice of bulking agent strongly influence how quickly these changes appear.
Development work on the compound, originally designated TH9507, focused on conditions in which reduced growth hormone signaling is thought to contribute to altered body composition. The United States Food and Drug Administration approved it in 2010 for the treatment of excess visceral abdominal fat in adults with human immunodeficiency virus infection and lipodystrophy. Later research examined other populations, including adults with mild cognitive impairment, where a large trial did not meet its primary endpoints. This mixed record illustrates how a single mechanism can produce clear effects in one setting and inconclusive results in another.
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.
质量控制项目一般包括外观、身份、纯度、含量、有关物质、水分和微生物限度。身份确认可通过肽图谱、氨基酸分析和质谱完成，纯度则用面积归一化法计算。研究级材料与药品级材料的要求不同，前者常缺少完整药典验证。不同批次间杂质谱是否影响活性，仍是一个需要具体数据回答的问题。
特沙莫瑞林的检测通常依赖反相高效液相色谱和质谱联用。反相色谱可分离肽主峰与缺失序列、氧化产物等杂质，质谱则提供精确质量以确认身份。对于复杂基质中的定量，常采用液相色谱-串联质谱，并配合固相萃取或蛋白沉淀。生物样品中的肽易降解，因此采集和处理条件会影响结果。
=== Acidity === Carboxylic acids are Brønsted–Lowry acids because they are proton (H+) donors. They are the most common type of organic acid. Carboxylic acids are typically weak acids, meaning that they only partially dissociate into [H3O]+ cations and R−CO−2 anions in neutral aqueous solution. For example, at room temperature, in a 1-molar solution of acetic acid, only 0.001% of the acid are dissociated (i.e. 10−5 moles out of 1 mol). Electron-withdrawing substituents such as trifluoromethyl (−CF3) give stronger acids (the pKa of acetic acid is 4.76 whereas trifluoroacetic acid, with a trifluoromethyl substituent, has a pKa of 0.23). Electron-donating substituents give weaker acids (the pKa of formic acid is 3.75 whereas acetic acid, with a methyl substituent, has a pKa of 4.76)
These models have a prominent bonnet scoop. At about the same time a all-wheel-drive model was introduced in Japan, either with a 1.6-litre petrol or the Isuzu turbo-diesel. The 4WD cars can be easily identified by having been equipped with the federalized front (but not rear) bumper, including side marker lights. The rare North American ES model came with the Miata (NA)'s 1.8-litre twin-cam engine (though the internals were not entirely the same), all-wheel disc brakes, and dual stabilizer bars. The same car went on sale in Australia in the second half of 1994 with a fully featured BP-ZE engine. The Protegé became classified as a "compact car" for the 1995 model year in North America. A version with Mazdaspeed accessories was released in Japan and Philippines. It came equipped with Mazdaspeed wrap around bodykit, Mazdaspeed rear spoiler, Momo steering wheel, 15-inch Rota Astral wheels wrapped in 195/55R15 Bridgestone Potenza RE01 tires, Mazdaspeed strut tower bar, Eibach springs, gas-charged shock absorbers, swaybars and Mazdaspeed exhaust made by Yumex. The Familia/Protegé/323 was facelifted in October 1996, with a newer somewhat calmer style. This generation was discontinued in 1998 in most markets, but continued to be available in some markets until 1999 or 2000. For example, the 3-door hatchback was available in Europe until October 2000.
=== Manipulating the interactions === The protein–DNA interactions can be modulated using stimuli like ionic strength of the buffer, macromolecular crowding, temperature, pH and electric field. This can lead to reversible dissociation/association of the protein–DNA complex.
=== Fed state === The glucose fatty acid cycle is also observed in the fed state after a high-fat meal or during exercise. This is when plasma concentrations of fatty acids or ketone bodies are increased. The glucose that is not oxidized is then rerouted to glycogen. This rerouting to glycogen explains the rapid resynthesis of muscle glycogen after exercise as well as the increased glycogen content in muscles found in starvation or diabetes. This mechanism replenishes the intermediates of the citric acid cycle.
Russian Cossacks are thought to originate on the border with the steppe, and stretching from the middle Volga to Ryazan and Tula, then breaking abruptly to the south and extending to the Dnieper via Pereyaslavl. This area was settled by a population of free people practicing various trades and crafts. These people, constantly facing the Tatar warriors on the steppe frontier, received the Turkic name Cossacks (Kazaks), which was then extended to other free people in Russia. Many Cumans, who had assimilated Khazars, retreated to the Principality of Ryazan (Grand Duchy of Ryazan) after the Mongol invasion. The oldest mention in the annals is of Cossacks of the Russian principality of Ryazan serving the principality in the battle against the Tatars in 1444. In the 16th century, the Cossacks (primarily of Ryazan) were grouped in military and trading communities on the open steppe, and began to migrate into the area of the Don.
Sources: en.wikipedia.org
. Magnetization as a function of time is defined by the Bloch equations. T1 and T2 values are dependent on the chemical environment of the sample; hence their utility in MRI. Soft tissue and muscle tissue relax at different rates, yielding the image contrast in a typical scan. The standard display of MR images is to represent fluid characteristics in black-and-white images, where different tissues turn out as follows:
The country was mostly savannah, although the moist and mountainous eastern highlands supported areas of tropical evergreen and hardwood forests. Trees found in these Eastern Highlands included teak, mahogany, enormous specimens of strangling fig, forest newtonia, big leaf, white stinkwood, chirinda stinkwood, knobthorn and many others. In the low-lying parts of the country, fever trees, mopane, combretum and baobabs abound. Much of the country was covered by miombo woodland, dominated by brachystegia species and others. Among the numerous flowers and shrubs were hibiscus, flame lily, snake lily, spider lily, leonotus, cassia, tree wisteria and dombeya. There were around 350 species of mammals that can be found in Rhodesia. There were also many snakes and lizards, over 500 bird species, and 131 fish species.
The following is a partial list of the "D" codes for Medical Subject Headings (MeSH), as defined by the United States National Library of Medicine (NLM). This list continues the information at List of MeSH codes (D12.644). Codes following these are found at List of MeSH codes (D13). For other MeSH codes, see List of MeSH codes. The source for this content is the set of 2006 MeSH Trees from the NLM.
== Sources == Latimer WM and Rodebush WH. (1920) "Polarity and Ionization from the Standpoint of the Lewis Theory of Valence", J. Am. Chem. Soc., 42, 1419–1433. Huggins ML. (1936) J. Org. Chem., 1, 407–456. Pauling L and Niemann C. (1939) J. Am. Chem. Soc., 61, 1860–1867. Huggins M. (1943) "The structure of fibrous proteins", Chem. Rev., 32, 195–218. Huggins ML. (1971) Angew. Chem. Int. Ed., 10, 147–152. Huggins ML. (1980) Chem. Tech., 10, 422.
Slavery, despite no longer being legally recognized anywhere in the world, is still prevalent in some form in all countries today, though some regions have more concentration of slaves: 60% in Asia and Pacific, 23% in Africa, 9% in Europe and Central Asia, 5% in the Americas, and 1% in Arab states. In 2019, approximately 40 million people, of whom 26% were children, were still enslaved throughout the world despite slavery being illegal. In the modern world, more than 50% of slaves provide forced labour, usually in the factories and sweatshops of the private sector of a country's economy. In industrialised countries, human trafficking is a modern variety of slavery; in non-industrialised countries, people in debt bondage are common, others include captive domestic servants, people in forced marriages, and child soldiers.
Sources: en.wikipedia.org
=== Scottish === Daughters of Scotland - Incorporated in Ohio on October 3, 1899. Membership is open only to those of Scottish blood. Rituals had signs, oaths, and prayers. Grand Lodge dissolved in the early 1970s, though some local groups continued to meet afterwards. Order of Scottish Clans Sons of Scotland Benevolent Association - Founded 1876 in Toronto. Incorporated in Ontario in 1880, and on the federal level in 1937. Headquartered in Toronto, the association's lodges are called "Subordinate Camps", and the national structure is "Grand Camp", which meets in conventions triennially. Slogan "Lealty, Loyalty, Liberality". In the late 1970s, it still had an initiation ceremony and "affinity for fraternal ritualism", annual passwords, and regalia. In addition to insurance, it sponsors Scottish dancing and piping competitions, and parades in Scottish kilts. Membership is open to men and women of Scottish descent or their spouses. Five classes of membership - insured, central camp, juvenile, associate, and at large. Members are chosen by blackball. 1973 membership 12,887; 1979 membership 12,640 in 80 camps. 9,000 members in 1995. Charitable activities include Kidney Foundation of Canada and Alzheimer's disease organizations. Lost a third of its membership over the 1980s.
Chromosome studies are used in the general genetics clinic to determine a cause for developmental delay or intellectual disability, birth defects, dysmorphic features, or autism. Chromosome analysis is also performed in the prenatal setting to determine whether a fetus is affected with aneuploidy or other chromosome rearrangements. Finally, chromosome abnormalities are often detected in cancer samples. A large number of different methods have been developed for chromosome analysis:
Compactituberculate - The dome-shaped tops of the shell units form a dense covering of nodes on the surface of the eggshell. This type of ornamentation is most commonly seen in megaloolithids. Sagenotuberculate - The nodes and ridges form a netlike pattern interspersed with pits and grooves. Dispersituberculate - Scattered nodes. This ornamentation is seen on the poles of elongated eggs, which may have allowed accumulations CO2 at the poles to escape between the nodes. Lineartuberculate - Ridges, and chains of ridges and nodes form lines parallel to the long axis of the egg. Ramotuberculate - Irregular chains of nodes, typically found as a transition between the lineartuberculate midsection and dispersituberculate ends of elongated eggs. Anastomotuberculate - Ridges similar to lineartuberculate, but instead form wavy, branching, or anastomosing patterns resembling the water ripple marks in sand.
It is also used off-label in the management of moderate to severe cases of serotonin syndrome, a complex of symptoms associated with the use of serotonergic drugs, such as selective serotonin reuptake inhibitors (and monoamine oxidase inhibitors), and in cases of high levels of serotonin in the blood resulting from a serotonin-producing carcinoid tumor. There is uncertainty about the proper dose of cyproheptadine for treatment of serotonin syndrome, with doses of 4 to 16 mg having been employed but doses of 20 to 30 mg possibly actually being necessary based on positron emission tomography (PET) imaging research. Cyproheptadine has sedative effects and can be used to treat insomnia similarly to other centrally-acting antihistamines. The recommended dose for this use is 4 to 8 mg.
Sources: en.wikipedia.org
It mimics a natural hypothalamic signal that tells the pituitary to release growth hormone. The result is a rise in circulating growth hormone and, indirectly, in insulin-like growth factor 1. Over weeks of treatment this shift is associated with a selective decrease in fat stored inside the abdomen.
The primary measure is usually a cross-sectional abdominal scan that separates internal fat from fat just under the skin. Waist circumference and body weight are recorded as secondary measures because they are easy to obtain but do not distinguish the two fat compartments. Hormone and metabolic blood tests are collected alongside the imaging.
Available follow-up data indicate that visceral fat drifts back toward pretreatment levels once injections stop. The change is therefore best described as treatment-dependent rather than permanent. Investigators continue to debate whether intermittent or repeated courses would preserve any benefit.
It shares the 44-residue sequence of human GHRH but carries an added trans-3-hexenoyl group at its N-terminus. That addition does not occur in the natural hormone and serves mainly to resist enzymatic breakdown. The receptor target and signaling pathway remain the same.