If you have been reading about 内毒素 and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-03-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
研究用与临床用材料的标准并不相同。质量控制通常覆盖纯度、残留溶剂、反离子含量、微生物限度与内毒素水平，各项均有对应检测方法。随货文件应包含批号、检测项目、方法与结果，使数据可以追溯。核验时应关注纯度是否按主峰面积计算、杂质是否已定性、方法是否经过验证，这些信息决定结果能否被外部重复。
Lyophilized tesamorelin is generally stored refrigerated at temperatures between 2 and 8 degrees Celsius. The solid form is comparatively stable when kept dry and protected from light. Moisture uptake can promote aggregation and degradation, so sealed containers with desiccant are common. Researchers typically avoid repeated temperature cycling, which may stress the peptide. Documentation accompanying reference materials usually specifies a shelf life under these conditions.
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.
| 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 |
Common analytical approaches include reversed-phase high-performance liquid chromatography for purity assessment and mass spectrometry for identity confirmation. Peptide mapping after enzymatic digestion can verify the expected sequence. Immunoassays may be used to measure the compound or its downstream markers, but they can cross-react with related peptides and require careful validation. Impurity profiles typically include truncated sequences, oxidized methionine residues, and residual solvents from synthesis. Each method reports a different property, so no single assay establishes overall quality.
Storage claims vary across suppliers, and published stability data for specific formulations are limited. Extrapolating from related peptides is common but not a substitute for direct measurement. For research use, documentation such as a certificate of analysis is often requested to confirm identity and purity. What constitutes an acceptable purity threshold depends on the intended application. Open questions remain about how temperature excursions during shipping affect long-term peptide integrity. Independent verification by an end user is not routinely reported.
Lyophilized material is typically held under refrigeration between two and eight degrees Celsius, shielded from light and ambient moisture. Peptides of this size adsorb to glass and plastic, so working procedures often call for low-binding containers and as few transfers as possible. Absorbed water during weighing shifts the apparent mass of a sample, and controlling room humidity reduces that source of error. Once dissolved, solutions are kept cold and used within the interval printed on the accompanying label or certificate. Degradation accelerates markedly in dilute aqueous form.
Identity and purity are judged through a combination of chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the intact peptide from truncated, oxidized, and deamidated variants, and the resulting peak-area percentages yield a purity figure. Electrospray ionization mass spectrometry confirms the expected molecular mass and can expose unanticipated modifications. Amino acid analysis and peptide mapping support sequence fidelity, while water content, pH, sterility, and bacterial endotoxin testing describe the physical and microbiological attributes of a finished lot.
Regulatory position depends on jurisdiction and on the form in which the material is sold. A branded product holds approval in the United States for a defined indication, and prescribing is confined to that label. Material marketed for laboratory research is not evaluated for human use and carries no such clearance. Independent verification therefore rests on certificates of analysis, third-party testing, and documented chain of custody. The substance also appears on the World Anti-Doping Agency prohibited list within the category covering growth hormone-releasing factors.
Tesamorelin binds to growth hormone-releasing hormone receptors on somatotroph cells in the anterior pituitary. Receptor activation increases intracellular cyclic AMP and promotes synthesis and secretion of growth hormone. Because the peptide mimics endogenous GHRH, it amplifies the normal pulsatile release of growth hormone rather than providing exogenous growth hormone directly. This upstream action distinguishes tesamorelin from recombinant growth hormone preparations and from growth hormone secretagogues that act at different receptors.
Stimulated growth hormone release leads to hepatic production of insulin-like growth factor 1, a key mediator of many growth hormone effects. In clinical studies, tesamorelin increased IGF-1 levels in a dose-dependent manner, although the response varies among individuals. The drug's effect on visceral fat is thought to involve growth hormone-mediated lipolysis and altered adipocyte metabolism. Muscle mass and lean body mass have also been assessed as secondary outcomes, but changes are generally smaller and less consistent than fat reductions.
Pharmacodynamic studies show that tesamorelin reduces visceral adipose tissue more than subcutaneous adipose tissue in the studied population. This selectivity may relate to differences in blood flow and hormone sensitivity between fat depots. Effects on glucose metabolism and insulin sensitivity have been investigated, with some trials reporting modest changes and others showing stability. The precise relationship between growth hormone exposure, IGF-1 levels, and visceral fat loss remains an active area of analysis.
Many physicians operate by the World Professional Association of Transgender Health (WPATH) Standards of Care (SoC) model and require psychotherapy and a letter of recommendation from a psychotherapist in order for a transgender person to obtain hormone therapy. Other physicians operate by an informed consent model and have no requirements for transgender hormone therapy aside from consent. Medications used in transgender hormone therapy are also sold without a prescription on the Internet by unregulated online pharmacies, and some transgender women purchase these medications and treat themselves using a do-it-yourself (DIY) or self-medication approach. One reason that many transgender people turn to DIY hormone therapy is due to long waiting lists of up to years for standard physician-based hormone therapy in some parts of the world such as the United Kingdom, as well as due to the often high costs of seeing a physician and the restrictive criteria that make some ineligible for treatment, or simply medical malpractice by physicians that are not adequately trained. The accessibility of transgender hormone therapy differs throughout the world and throughout individual countries.
=== 1. FC Lokomotive (since 2003–04) === In late 2003, the club was re-established by a group of fans as 1. FC Lokomotive Leipzig. The renewed side had to start in the lowest league, eleventh-tier 3. Kreisklasse, Staffel 2, in 2004–05. Even so, they continued to receive solidly enthusiastic fan support: their match against Eintracht Großdeuben's second team in the Leipzig Zentralstadion on 9 October 2004, broke the world record for lower-league attendance with 12,421 spectators. Thanks to a merger with SSV Torgau, the club could play in the seventh-tier Bezirksklasse Leipzig, Staffel 2, in 2005–06. Finishing this league as champions, the team qualified for the sixth-tier Bezirksliga. In 2006, 1. FC Lokomotive Leipzig also played a friendly match against FC United of Manchester (4–4) and qualified for the 2006–07 Landespokal by winning the Bezirkspokal. 1. FC Lokomotive Leipzig finished as champions of their group and were promoted to the fifth-tier Landesliga Sachsen Group for the 2007–08 season. The club finished second to Erzgebirge Aue and missed out on direct promotion to the NOFV-Oberliga Süd by two points in the 2007–08 season. It still had the chance to regain Oberliga status through a relegation play-off with Schönberg, winning the first leg 2–1 at Schönberg. In the return leg, in front of almost 10,000 spectators, the club lost 0–1 but still gained Oberliga promotion via the away goals rule. 1. FC Lokomotive Leipzig finished the Oberliga in third place in 2008–09, 12th in 2009–10, and eighth in 2010–11. 1.
== Prognosis == Generally, long-term prognosis is helpful to survival of initial exposure to nitrogen dioxide. Some cases of nitrogen dioxide poisoning resolves with no observable symptoms and patient may be determined by pulmonary function testing. If chronic exposure causes lung damage, it could take several days or months for the pulmonary function to improve. Meanwhile, permanent mild dysfunction may result from bronchiolitis obliterans and could manifest as abnormal flow at 50 to 70 percent of vital capacity. It may also manifest as mild hyperinflammation, airway obstruction and in that case, patient may be subject to steroid treatment to treat deconditioning. Complications from prolong exposure includes bronchiolitis obliterans and other secondary infections such as pneumonia due to injuries on the mucous membrane from pulmonary edema and inhibition of immune system by nitrogen dioxide. Nitrogen dioxide inhalation can result in short and long-term morbidity or death depending on the extent of exposure and inhaled concentration and the exposure time. Illness resulting from acute exposure is usually not fatal although some exposure may cause bronchiolitis obliterans, pulmonary edema as well as rapid asphyxiation. If the concentration of exposure is excessively high, the gas may displace oxygen resulting in fatal asphyxiation. Generally, patients and workers should be educated by medical personnel on how to identify the signs and symptoms of Nitrogen dioxide poisoning.
Sources: en.wikipedia.org
Dry ice has found its application in construction for freezing soil, serving as an effective alternative to liquid nitrogen. This method reduces the soil temperature to approximately -70 to -74 °C, rapidly freezing the groundwater. As a result, the soil's strength and impermeability significantly increase, which is essential for the safe execution of underground construction projects. It is also useful as a cutting fluid.
On July 21, 1945, Second Lieutenant Mario López Portillo along with another pilot from 311th Squadron crashed into a mountain nearby, dying in the process. The casualties of these pilots would be a serious blow to 201st Squadron, meanwhile, the fifth force moved to Okinawa to continue harassment attacks on the Japanese. The Mexican Expeditionary Air Force was assigned to the service group of 311th Squadron, and on August 24, it carried out an escort mission to a convoy north of the Philippine Sea to prevent Japanese attacks. After intense fighting and losing companions, the mission had been accomplished. The atomic bombings of the cities of Hiroshima and Nagasaki occurred on the 6th and 9th of August, 1945. Given these attacks, further losses on all fronts, and the Soviet invasion of Manchuria also on August 9, the Empire of Japan finally offered its unconditional surrender on August 15, 1945, which was formalized with a solemn signature on September 2 in Tokyo Bay. During their involvement in the war, Mexican troops were credited with putting 30,000 Japanese soldiers out of action and destroying held buildings, vehicles, tanks, anti-aircraft machine guns, emplaced machine guns, and ammunition depots. Douglas MacArthur, Supreme Command Allied Forces in Southwest Pacific Area, was impressed with the work performed by the squadron. Years later, it was announced that the Mexican troops were going to combat in the European Theater.
== Family == The Hoffmann-La Roche family is Switzerland's richest and one of the most secretive families. Many members of the family don't carry the last name Hoffmann anymore. Some are known as Oeri, Michalski, Faber-Castell, Fabre, Schmid or Duschmalé.
In combined mass spectra obtained by summing a large number of individual ion detection events, each peak is a histogram obtained by adding up counts in each individual bin. Because the recording of the individual ion arrival with TDC yields only a single time point, the TDC eliminates the fraction of peak width determined by a limited response time of both the MCP detector and preamplifier. This propagates into better mass resolution. Modern ultra-fast 10 GSample/sec analog-to-digital converters digitize the pulsed ion current from the MCP detector at discrete time intervals (100 picoseconds). Modern 8-bit or 10-bit 10 GHz ADC has much higher dynamic range than the TDC, which allows its usage in MALDI-TOF instruments with its high peak currents. To record fast analog signals from MCP detectors one is required to carefully match the impedance of the detector anode with the input circuitry of the ADC (preamplifier) to minimize the "ringing" effect. Mass resolution in mass spectra recorded with ultra-fast ADC can be improved by using small-pore (2-5 micron) MCP detectors with shorter response times.
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。
Refrigeration between 2 and 8 degrees Celsius is typical, with protection from moisture and light. Dry, sealed containers help maintain stability over the labeled shelf life. Temperature cycling is usually minimized.