The short version of IGF-1 fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-06-25 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.
== Effects on nutrients == The process of flash freezing itself generally effectively retain the nutrient content of foodstuff with minor losses of vitamins, making them a cost-effective and nutritious substitute from fresh equivalents. However, pre-seasoned frozen food, such as packaged meals, may have a significant amounts of salt and fats added. It is therefore recommended to read the nutrition label and the ingredients list.
Tofu (Japanese: 豆腐, Hepburn: Tōfu; Chinese: 豆腐; pinyin: dòufu; Korean: 두부; RR: dubu) or bean curd is a food prepared by pressing the curds of coagulated soy milk into solid white blocks of varying softness: 'silken', 'soft', 'firm', and 'extra (or super) firm'. It originated in China and has been consumed for over 2,000 years. Tofu is a traditional component of many East Asian and Southeast Asian cuisines; in modern Western cooking, it is commonly used as a meat substitute. Nutritionally, tofu is low in calories, while providing a rich source of protein. Cultivation of soybeans has one of the lowest needs for land use (1.3 m2/ 1000 kcal) and emits some of the lowest amounts of greenhouse gas emissions per gram of edible protein of any food (1.6 kg CO2/ 100 g protein).
...some of the actions adopted by those aiming to stop tours were despicable. Bette [Bill McLaren's wife] and I were referred to as 'racist scum' on our way down to Mansfield Park to see the South African Barbarians play in 1979 – a tour party comprising equal numbers of coloureds, blacks and whites. That, said the protesters, was just window dressing. When the Springboks last toured the UK, I was asked to provide commentary on their match against the Midland Counties (East) at Welford Road, Leicester. I remember having to walk the gauntlet up a narrow channel lined on each side by policemen holding back the mob. Those policemen were covered in spittle, had hats knocked off, were kicked in places where no man should be kicked, and yet took it all with stoic calm. I couldn't believe that people in the British Isles would behaved in that manner.... Constant noise outside the South Africans' hotels to try and prevent them sleeping was another unbelievable ploy that sickened decent people.
Sources: en.wikipedia.org
In Costa Rica, public universities include the University of Costa Rica, the National University, the Distance State University, National Technical University and the Costa Rica Institute of Technology.
Magnesium is a chemical element; it has symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point, and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic table), it occurs naturally only in combination with other elements and almost always has an oxidation state of +2. It reacts readily with air to form a thin passivation coating of magnesium oxide that inhibits further corrosion of the metal. The free metal burns with a brilliant-white light. The metal is obtained mainly by electrolysis of magnesium salts obtained from brine. It is less dense than aluminium and is used primarily as a component in strong and lightweight alloys that contain aluminium. In the cosmos, magnesium is produced in large, aging stars by the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, much of the magnesium is expelled into the interstellar medium, where it may recycle into new star systems. Magnesium is the eighth most abundant element in Earth's crust and the fourth most common element in the Earth (after iron, oxygen and silicon), making up 13% of the planet's mass and a large fraction of the planet's mantle. It is the third most abundant element dissolved in seawater, after sodium and chlorine. This element is the eleventh most abundant element by mass in the human body and is essential to all cells and some 300 enzymes. Magnesium ions interact with polyphosphate compounds such as ATP, DNA, and RNA. Hundreds of enzymes require magnesium ions to function.
The Scientific Research Publishing (SCIRP) is a predatory academic publisher of open-access electronic journals, conference proceedings, and scientific anthologies that are of questionable quality. As of December 2014, it offered 244 English-language open-access journals in the areas of science, technology, business, economy, and medicine. The company has been accused of using email spam to solicit papers for submission. Although it has an address in southern California, according to Jeffrey Beall it is a Chinese operation. In 2014 there was a mass resignation of the editorial board of one of the company's journals, Advances in Anthropology, with the outgoing editor-in-chief saying of the publisher "For them it was only about making money. We were simply their 'front'."
== Applications == Actin beta is often used in Western blotting as a loading control, to normalize total protein amounts and check for eventual protein degradation in the samples. Its transcript is also commonly used as a housekeeping gene standard in qPCR. Its molecular weight is approximately 42 kDa.
Sources: en.wikipedia.org
== Clinical significance == The loss of CD38 function is associated with impaired immune responses, metabolic disturbances, and behavioral modifications including social amnesia possibly related to autism. CD31 on endothelial cells binds to the CD38 receptor on natural killer cells for those cells to attach to the endothelium. CD38 on leukocytes attaching to CD31 on endothelial cells allows for leukocyte binding to blood vessel walls, and the passage of leukocytes through blood vessel walls. The cytokine interferon gamma and the Gram negative bacterial cell wall component lipopolysaccharide induce CD38 expression on macrophages. Interferon gamma strongly induces CD38 expression on monocytes. The cytokine tumor necrosis factor strongly induces CD38 on airway smooth muscle cells inducing cADPR-mediated Ca2+, thereby increasing dysfunctional contractility resulting in asthma. The CD38 protein is a marker of cell activation. It has been connected to HIV infection, leukemias, myelomas, solid tumors, type II diabetes mellitus and bone metabolism, as well as some genetically determined conditions. CD38 increases airway contractility hyperresponsiveness, is increased in the lungs of asthmatic patients, and amplifies the inflammatory response of airway smooth muscle of those patients.
The ELP tags have been used in the fusion protein of intein, so that the aggregates can be isolated without chromatography (by centrifugation) and then intein and tag can be cleaved in controlled manner to release the target protein into solution. This protein isolation can be done using continuous media flow, yielding high amounts of protein, making this process more economically efficient than conventional methods. Another group of researchers used smaller self aggregating tags to isolate target protein. Small amphipathic peptides 18A and ELK16 (figure 5) were used to form self cleaving aggregating protein.
Kedarcidin is a chromoprotein antitumor antibiotic first isolated from an Actinomycete in 1992, comprising an ansa-bridged enediyne chromophore (shown) as well as an apoprotein that serves to stabilize the toxin in the Actinomycete. Like other members of the enediyne class of drugs—so named for the nine-or-ten-membered core structure bearing an alkene directly attached to two alkynyl appendages—kedarcidin was likely evolved to kill bacteria that compete with the producing organism. Because it achieves this by causing DNA damage, however, kedarcidin is capable of harming tumor cells, as well. Kedarcidin is thus the subject of scientific research, both for its structural complexity as well as its anticancer properties.
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.