This is a working overview of IGF-1, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-01 and is reviewed periodically as new material appears.
纯度与身份确认依赖色谱与质谱的组合。反相高效液相色谱在 214 nm 紫外检测下分离主峰与相关杂质，给出纯度百分比与保留时间；电喷雾或基质辅助激光解吸电离质谱提供分子量，用于确认 N 端修饰是否完整。序列层面可通过肽图或氨基酸分析验证。含量测定常用紫外吸收法或氮元素分析，不同方法之间需要做交叉校验。
冻干粉末一般在 -20°C 或更低温度、干燥避光条件下保存，可维持较长时间的稳定。复溶后稳定性明显下降，溶液中的肽链易发生水解、氧化与聚集，通常需冷藏并在短期内用完。反复冻融会加速聚集与降解，建议分装后单次使用。缓冲体系的 pH 与离子强度同样影响聚集速率，需要按具体实验条件验证。
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.
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.
| 性质 | 取值 | 备注 |
|---|---|---|
| 外观 | 白色至类白色冻干粉 | 常见形态 |
| 溶解性 | 易溶于水与水性缓冲液 | 多肽类通性 |
| 典型储存温度 | -20°C 或更低 | 干燥避光 |
| 常用纯度方法 | 反相高效液相色谱 | 214 nm 紫外检测 |
| 常用分子量确认 | 质谱 | 电喷雾或激光解吸 |
Once reconstituted, the peptide is handled as a solution and is less stable than the lyophilized powder. Aqueous solutions are commonly kept cold and used within a defined period. Buffer composition and pH influence degradation rates, with extremes of acidity or alkalinity accelerating hydrolysis. Preservatives may be added in multi-dose formats to limit microbial growth. Freezing and thawing of solutions is generally avoided because it can cause precipitation or loss of activity.
Identity and purity are assessed by reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass and detects chemical modifications. Peptide mapping and amino acid analysis can verify sequence integrity. Water content is measured by Karl Fischer titration, and residual solvents may be checked by gas chromatography. These methods together support batch-to-batch consistency and routine quality control.
Tesamorelin is a synthetic analog of growth hormone-releasing hormone, a peptide hormone produced by the hypothalamus. The molecule retains the 44-amino-acid sequence of human GHRH and carries a trans-3-hexenoyl modification at its N-terminus. This modification increases resistance to enzymatic degradation and extends the peptide's functional stability relative to native GHRH. The compound is supplied as a lyophilized powder for reconstitution and subcutaneous administration in clinical settings. Its development code was TH9507, and it belongs to the GHRH analog class. It is not a growth hormone product; instead, it acts upstream to stimulate endogenous growth hormone release.
Clinical interest in tesamorelin arose from the need to address visceral adiposity in people living with HIV. Antiretroviral therapy improved survival but was associated in some patients with central fat accumulation, altered lipid profiles, and metabolic complications. This condition, often called HIV-associated lipodystrophy, involves excess visceral adipose tissue that is difficult to manage through diet and exercise alone. Investigators evaluated tesamorelin because GHRH analogs can stimulate growth hormone secretion and influence fat distribution without direct liposuction or invasive procedures.
A Phase 3 program led to regulatory approval in the United States in 2010 for reduction of excess visceral abdominal fat in adults with HIV and lipodystrophy. Subsequent studies examined effects on liver fat, muscle area, and metabolic markers, with mixed findings for some endpoints. Long-term cardiovascular outcomes and effects on mortality remain uncertain because most trials were relatively short and focused on imaging-based fat measurements. Use in populations without HIV has been studied experimentally but is not part of the approved indication.
If two neighboring carbon atoms are labeled, a doublet of doublets may degenerate into a triplet if the doublet splittings are equal. The drawbacks to using NMR techniques for metabolic flux analysis purposes is that it is different from other NMR applications because it is a rather specialized discipline. An NMR spectrometer may not be directly available for all research teams. The optimization of NMR measurement parameters and proper analysis of peak structures requires a skilled NMR specialist. Certain metabolites also may require specialized measurement procedures to obtain additional isotopomer data. In addition, specially adapted software tools are needed to determine the precise quantity of peak areas as well as identifying the decomposition of entangled singlet, doublet, and triplet peaks. As opposed to nuclear magnetic resonance, mass spectrometry (MS) is another method that is more applicable and sensitive to metabolic flux analysis experiments. MS instruments are available in different variants. Different from two-dimensional nuclear magnetic resonance (2D-NMR), the MS instruments work directly with hydrolysate. In gas chromatography-mass spectrometry (GC-MS), the MS is coupled to a gas chromatograph to separate the compounds of the hydrolysate. The compounds eluting from the GC column are then ionized and simultaneously fragmented. The benefit in using GC-MS is that not only are the mass isotopomers of the molecular ion measured but also the mass isotopomer spectrum of several fragments, which significantly increases the measured information.
Garcia E, Rhee SG (1983). "Cascade control of Escherichia coli glutamine synthetase Purification and properties of PII uridylyltransferase and uridylyl-removing enzyme". J. Biol. Chem. 258 (4): 2246–53. doi:10.1016/S0021-9258(18)32914-4. PMID 6130097. van Heeswijk WC, Rabenberg M, Westerhoff HV, Kahn D (1993). "The genes of the glutamine synthetase adenylylation cascade are not regulated by nitrogen in Escherichia coli". Mol. Microbiol. 9 (3): 443–57. doi:10.1111/j.1365-2958.1993.tb01706.x. PMID 8412694. S2CID 8691388.
== Properties == In 1969, strong piezoelectricity was observed in PVDF, with the piezoelectric coefficient of poled (placed under a strong electric field to induce a net dipole moment) thin films as large as 6–7 pC/N: 10 times larger than that observed in any other polymer. PVDF has a glass transition temperature (Tg) of about −35 °C and is typically 50–60% crystalline. To give the material its piezoelectric properties, it is mechanically stretched to orient the molecular chains and then poled under tension. PVDF exists in several phases depending on the chain conformations as trans (T) or gauche (G) linkages: TGTG' for α and δ phase, TTTT for β phases, and TTTGTTTG' for γ and ε phases. The α and ε conformations lack piezoelectric properties because of the antiparallel alignment of dipoles within its unit cell. The β, γ, and δ phases feature a parallel arrangement of dipoles, rendering them polar crystals with a non-zero dipole moment. Among these phases, the β phase stands out due to its remarkable remnant polarization and the highest dipolar moment per unit cell, garnering more interest compared to the others. When poled, PVDF is a ferroelectric polymer, exhibiting efficient piezoelectric and pyroelectric properties. These characteristics make it useful in sensor and battery applications. Thin films of PVDF are used in some newer thermal camera sensors. Unlike other popular piezoelectric materials, such as lead zirconate titanate (PZT), PVDF has a negative d33 value.
Sources: en.wikipedia.org
Apart from X-ray crystallography, important analytical techniques for the characterization of metal carbonyls are infrared spectroscopy and 13C NMR spectroscopy. These two techniques provide structural information on two very different time scales. Infrared-active vibrational modes, such as CO-stretching vibrations, are often fast compared to intramolecular processes, whereas NMR transitions occur at lower frequencies and thus sample structures on a time scale that, it turns out, is comparable to the rate of intramolecular ligand exchange processes. NMR data provide information on "time-averaged structures", whereas IR is an instant "snapshot". Illustrative of the differing time scales, investigation of dicobalt octacarbonyl (Co2(CO)8) by means of infrared spectroscopy provides 13 νCO bands, far more than expected for a single compound. This complexity reflects the presence of isomers with and without bridging CO ligands. The 13C NMR spectrum of the same substance exhibits only a single signal at a chemical shift of 204 ppm. This simplicity indicates that the isomers quickly (on the NMR timescale) interconvert.
== Selective ligands == Numerous selective inhibitors of SIRT2 are known as they have antiviral effects and potential application in cancer treatment, though none of them has been conclusively shown to be highly selective for SIRT2 over all other SIRT subtypes. No highly selective activators of SIRT2 are known at present with non selective activators such as nicotinamide riboside mainly used for research.
=== For evaluative well-being (life satisfaction) === Mental health is the strongest individual predictor of life satisfaction. Mental illness is associated with poorer well-being. In fact, mental health is the strongest determinant of quality of life at a later age. Studies have documented the relationship between anxiety and quality of life. The VOXEU analysis of happiness showed the principal determinants of an adult's life satisfaction to be income, parenting, family break up, mother's mental health and schooling. The factors that explain life satisfaction roughly map (negatively) to those factors that explain misery. They are first and foremost diagnosed depression/anxiety, which explains twice as much as the next factor, physical health (number of medical conditions), that explains just as much variance in subjective well-being between people, as income and whether someone is partnered. These factors count twice as much as each of whether someone is employed and whether they are a non-criminal, which in turn are 3 times as important as years of education. Overall, the best predictor of an adult's life satisfaction is their emotional health as a child as reported by the mother and child. It trumps factors like the qualifications that someone gets and their behaviour at 16 as reported by the mother. A child and therefore an adult's emotional health is most affected itself by a mother's mental health, which is just over twice as important as family income.
Mammals such as lemurs and monkeys demonstrate application of chemicals similar to how humans use chemicals for pest management and medical use. These applications vary from prevention of internal and external parasites or pathogens, decrease likelihood of infection, increase reproductive function, reducing inflammation, social cues, and more. Red-fronted lemurs (Eulemur ruffrons) have evolved two pathways, preventive measure for avoiding bioaccumulation, allowing for the modification of 2-methyl-1,4-benzoquinone and 2-methoxy-3-methyl-1,4-benzoquinone a secretion of Spirostreptidae millipedes shown to inhibit certain bacterial species. Red-fronted lemurs have also been observed in rubbing the secretion on their fur similar to capuchins, this action uses benzoquinone compounds as repellent for various insects such as ticks and mosquitoes.
Sources: en.wikipedia.org
Following the sale of lots, Knoxville's leaders set about constructing a courthouse and jail. A garrison of federal soldiers, under the command of David Henley, erected a blockhouse in Knoxville in 1792. The Cowan brothers, Nathaniel and Samuel, opened the city's first general store in August 1792, and John Chisholm's tavern was in operation by December 1792. The city's first newspaper, the Knoxville Gazette, was established by George Roulstone in November 1791. In 1794, Blount College, the forerunner of the University of Tennessee, was chartered, with Samuel Carrick as its first president. Carrick also established the city's first church, the First Presbyterian Church, though a building wasn't constructed until 1816.
In Italy, Gasparo Tagliacozzi (1546–1599), professor of surgery and anatomy at the University of Bologna, published Curtorum Chirurgia Per Insitionem (The Surgery of Defects by Implantations, 1597), a technico–procedural manual for the surgical repair and reconstruction of facial wounds in soldiers. The illustrations featured a re-attachment rhinoplasty using a biceps muscle pedicle flap; the graft attached at 3-weeks post-procedure; which, at 2-weeks post-attachment, the surgeon then shaped into a nose. In Great Britain, Joseph Constantine Carpue (1764–1846) published the descriptions of two rhinoplasties: the reconstruction of a battle-wounded nose, and the repair of an arsenic-damaged nose. (cf. Carpue's operation).
Jennings was also appointed as a pitchman for Wisconsin even outside the specialized burger promotion, in a contract signed on October 1, 2009; in exchange, A&W donated $10,000 to The Greg Jennings Foundation. In January 2013, A&W Restaurants appointed Lexington-based advertising agency Cornett Integrated Marketing as its new agency of record. The contract was renewed in January 2024. In January 2019, ahead of its hundredth anniversary, A&W removed the ampersand from its logo as part of a tongue-in-cheek campaign to bring back the ampersand to the alphabet as its 27th letter. Beginning in October 2020, in order to recoup economic losses from the closure of several of its restaurants, A&W set up a series of quizzes on its website. For Halloween that year, it released a web stunt called The Onion Ring, a parody of The Ring. A&W unveiled a new campaign in 2024, capitalizing on the ampersand of its logo and the tagline Burgers, Floats & Then Some. Packaging was also changed accordingly.
Sources: en.wikipedia.org
多肽在反相柱上按疏水性差异分离，能有效区分主峰、缺失序列片段与氧化产物。配合紫外检测可获得可量化的纯度百分比，是肽类分析的常规手段。
一般建议密封、避光、干燥，并在 -20°C 或更低温度下存放。温度波动和湿气是主要风险，长期存放应避免反复开启容器。
没有统一答案，取决于缓冲液、浓度、pH 与储存温度。多数做法是冷藏并在数天至数周内用完，具体期限需要通过稳定性实验确认。
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.