lyophilization raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-04-30. Anything still debated is marked as such rather than presented as settled.
容器与密封系统同样参与稳定性表现。硅油涂层、胶塞材质与顶空氧含量可能改变聚集速率与氧化水平。分析结果因此需要在完整包装形式下评估，而不能仅凭原料药数据推断。法规文件通常要求同时提交批次数据与代表性容器中的稳定性趋势。
关于降解产物的免疫原性风险，文献中仍有讨论空间。体外聚集水平与临床免疫反应之间的定量关系尚未确立。多数公开研究只报告理化指标，缺少长期随访的对应数据。这一问题在生物类似物比对中尤其受到关注。
市售注射用制剂通常要求在二至八摄氏度冷藏保存，并避免光照与冻结。部分多剂量笔在首次使用后允许在不超过三十摄氏度的环境中存放有限周数，具体期限由辅料与防腐剂体系决定。反复冻融会促进肽链聚集并改变可见颗粒计数，因此应予避免。冻干粉末在干燥、避光、低温条件下更为稳定。溶液配制后宜使用低吸附容器，以减少肽类在塑料或玻璃表面的损失。
Native GLP-1 is degraded rapidly by dipeptidyl peptidase-4. Semaglutide resists this cleavage because alanine at position 8 is replaced by alpha-aminoisobutyric acid. A second substitution at position 34 introduces arginine, which further stabilizes the peptide. The most distinctive modification is a spacer and C18 fatty diacid attached at lysine 26, enabling strong albumin affinity. These three changes together produce a half-life measured in days rather than minutes, and the same structural logic underlies other long-acting analogs in this class.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L-cells after food intake. It contains 31 amino acids and differs from native GLP-1 through modifications that slow enzymatic breakdown. The peptide was developed to extend the short circulating half-life of endogenous GLP-1, which is measured in minutes. Researchers introduced the compound in the early 2010s. Two backbone changes and a fatty acid side chain define its structure, distinguishing it from earlier GLP-1 receptor agonists.
| Property | Value | Notes |
|---|---|---|
| 保存温度 | 2 至 8 摄氏度 | 避免冻结，部分制剂允许短期室温 |
| 粉末外观 | 白色至类白色固体 | 吸湿后易结块 |
| 纯度检测方法 | 反相高效液相色谱 | 紫外检测，常用 214 纳米 |
| 分子量确认方法 | 液相色谱串联质谱 | 偏差通常以 ppm 表示 |
| 常见降解产物 | 氧化与脱酰胺变体 | 源自甲硫氨酸与天冬酰胺残基 |
Quality control for research material typically involves reversed-phase HPLC for purity and identity, mass spectrometry for molecular weight confirmation, and Karl Fischer titration for residual water content. Peptide content is often reported as the mass of actual peptide rather than total powder mass, since counterions and water contribute to the latter. A certificate of analysis should list the method used for each specification. Limits and acceptance criteria vary by supplier and by intended application.
Handling practices center on minimizing contamination and adsorption. Lyophilized peptide tends to accumulate static charge, so weighing is done with antistatic measures and calibrated balances. Reconstitution with appropriate solvent should be gentle, avoiding vigorous vortexing that generates foam and shear. Solutions are typically aliquoted before freezing to reduce repeated temperature cycling. Personal protective equipment and a fume hood are standard for powder handling.
Handling guidance for research quantities calls for single-use aliquots, an inert atmosphere where practical, and avoidance of repeated freeze-thaw cycles that accelerate aggregation. Certificates of analysis typically report purity by peak area, water content, counter-ion identity, and residual solvent levels. In the scientific literature the compound is usually described by its full amino acid sequence, its registry number, or its structural class rather than by any proprietary label. Reporting standards vary between journals, and reviewers increasingly request raw chromatograms alongside tabulated purity figures. Whether current purity thresholds are adequate for every experimental context is debated.
Reversed-phase high-performance liquid chromatography with ultraviolet detection is the dominant approach for peptide purity assessment, usually paired with mass spectrometry to confirm molecular mass and sequence. Peptide mapping by enzymatic digestion and tandem mass spectrometry locates modifications such as deamidation and oxidation. Quantitation in plasma matrices can be performed by LC-MS/MS after solid-phase extraction. Method validation follows general guidance on accuracy, precision, linearity, and limits of detection. Comparability of results between laboratories, when no shared reference standard is available, remains an open question.
Identity and purity are assessed with reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities by hydrophobicity. Mass spectrometry confirms molecular weight and detects truncation or modification products. Peptide mapping after enzymatic digestion verifies the amino acid sequence. Quantitation is often performed by LC-MS/MS or by immunoassay, and the two approaches can give different values because they measure different things. Method validation parameters such as accuracy, precision, and limit of quantitation are reported alongside results.
Certificate of analysis documents from suppliers typically report purity by chromatographic area, water content, and counter-ion identity. Independent verification is advisable because reported values can be generated under differing conditions. Impurity profiles matter for research use, where aggregates, deamidation products, and residual solvents may influence experimental results. Container, lot, and chain-of-custody records support traceability. Analytical results are method-dependent, so comparisons between laboratories require the same procedure and reference standards.
Quality control for peptide material focuses on identity, purity, content and the profile of impurities. Common degradants include deamidated and oxidised forms, plus aggregates formed during storage or handling. Forced degradation studies under heat, light, acid and peroxide help define which conditions accelerate change and which analytical methods detect it. Limits for individual impurities are set by pharmacopoeial monographs or manufacturer specifications. How much a given impurity affects biological activity is often uncertain, and conclusions may depend on the assay used.
Solid peptide material is generally kept at reduced temperature to limit degradation. Short-term storage at 2 to 8 degrees Celsius is common, while longer archival storage at minus 20 degrees Celsius or below is typical for lyophilised powder. Vials should remain sealed and protected from light, because ultraviolet exposure can oxidise susceptible residues. Repeated freeze-thaw cycles are avoided, as they promote aggregation and loss of soluble material. Solutions are less stable than solids and are usually prepared close to the time of use.
== Characterization == The glutathione peroxidase family consists of 8 known human isoforms. Glutathione peroxidases use glutathione as an electron donor and are active with both hydrogen peroxide and organic hydroperoxide substrates. Gpx1, Gpx2, Gpx3, and Gpx4 have been shown to be selenium-containing enzymes, whereas Gpx6 is a selenoprotein in humans with cysteine-containing homologues in rodents. Amyloid beta, when bound to heme, has been shown to have peroxidase activity. A typical group of peroxidases are the haloperoxidases. This group is able to form reactive halogen species and, as a result, natural organohalogen substances. A majority of peroxidase protein sequences can be found in the PeroxiBase database.
== Cytotoxics and targeted therapies == Targeted therapies are a relatively new class of cancer drugs that can work to overcome many of the adverse effects seen with the use of cytotoxics. They are divided into two groups: small molecule and antibodies. The typical widespread toxicity observed with the use of cytotoxics is due to the lack of cell specificity of the drugs allowing them to kill any rapidly dividing cell, both cancerous and normal. Targeted therapies however, are designed to affect cellular proteins or processes that are utilized by the cancer cells. This allows a high dose administration to cancer tissues with a relatively low dose to other tissues. Although the side effects are often less severe than that seen of cytotoxic chemotherapeutics, life-threatening effects can occur. Initially, the targeted therapeutics were supposed to be solely selective for one protein. Now it is clear that there is often a range of protein targets that the drug can bind. An example target for targeted therapy is the BCR-ABL1 protein produced from the Philadelphia chromosome, a genetic lesion found commonly in chronic myelogenous leukemia and in some patients with acute lymphoblastic leukemia. This fusion protein has enzyme activity that can be inhibited by imatinib, a small molecule drug. Another example of target therapy is fludarabine cyclophosphamide (FC) lymphodepletion therapy used in patients with B cell lymphoma. This anti-CD19 CAR-T cell therapy is commonly known to decrease CAR-T cells which bind to the glycoprotein CD19.
"On the basis of creativity, and research and development, JEOL (日本電子) positively challenges the world’s highest technology thus forever contributing to the progress in both science and human society through its products." In commemoration of JEOL's 20th anniversary, the Kazato Research Foundation was created to support electron microscopy research. Kenji Kazato retired as president of JEOL in 1975, but continued to act as an adviser to the company until his death in 2012. Kazuo Ito was JEOL's president from 1982 to 1987. The Pittcon Heritage Award was posthumously awarded to them in 2016 for their contributions to scientific instrumentation. In 2014, a STEM resolution of 45 pm with a 300 kV microscope was first demonstrated with the atomic transmission electron microscope JEM-ARM300F.
== Locations == Most Pyongyang restaurants are found near the North Korean border in China, as well as in Beijing and Shanghai. Since the 2000s, the chain has been expanding into South and Southeast Asian cities including Phnom Penh, Siem Reap, Ho Chi Minh City, Hanoi, Da Nang, Vientiane, Dhaka, Jakarta, and Kuala Lumpur. There are also restaurants in Ulaanbaatar, Vladivostok, Moscow, and Kathmandu. The restaurants initially catered to the many South Korean businessmen in Southeast Asia, and have now become popular with curious tourists. The first Western outpost of the restaurant chain was opened in Amsterdam in 2012, in the residential neighbourhood of Osdorp, along with Dutch co-owners. The menu and policies of this restaurant differed from its Asian counterparts. However, in September 2012, amid mutual accusations between the Korean staff and the Dutch partner, the restaurant closed. It reopened in December 2013 under the name Haedanghwa in a new location, but closed a year later. The restaurant's locations in Bangkok were temporarily shut down, but were re-opened again in 2015. Similarly, their branches in Pattaya were closed down. The branch in Ho Chi Minh City closed down in 2017 and the branch in Hanoi shut down in 2020. It was reported that a new branch was set to open in Scotland, in line with North Korean leader Kim Jong Un's interest in the country after its 2014 independence referendum, although this has been denied by North Korean officials. In 2017, there are some 100 North Korean restaurants in China alone.
== External links == Gene Ontology: GO:0003720: telomerase activity Human telomerase reverse transcriptase (TERT) gene on genecards.org The Telomerase Database - A Web-based tool for telomerase research Archived 2021-04-19 at the Wayback Machine Three-dimensional model of telomerase at MUN Elizabeth Blackburn's Seminars: Telomeres and Telomerase Telomerase at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Overview of all the structural information available in the PDB for UniProt: O14746 (Human Telomerase reverse transcriptase) at the PDBe-KB. Overview of all the structural information available in the PDB for UniProt: Q0QHL8 (Tribolium castaneum Telomerase reverse transcriptase) at the PDBe-KB.
Sources: en.wikipedia.org
== Artwork == The album cover features an award-winning photograph by Spanish-born Catalan photojournalist and photographer Samuel Aranda. It shows a mother, Fatima al-Qaws embracing her son Zayed who is suffering from the effects of tear gas after taking part in a street demonstration against the then-ruling President Ali Abdullah Saleh in Sana'a, Yemen, on October 15, 2011. The photo was awarded the World Press Photo of the Year 2012 in February, 2012.
Comecon Frascati Manual German Marshall Fund Good laboratory practice International organisations in Europe International Transport Forum List of country groupings List of multilateral free trade agreements Marshall Plan OECD Anti-Bribery Convention OECD Better Life Index OECD Environmental Performance Reviews OECD Working Party on SMEs and Entrepreneurship Official development assistance Organization for Security and Co-operation in Europe Transfer pricing
A computational method, IPRO, recently predicted mutations that experimentally switched the cofactor specificity of Candida boidinii xylose reductase from NADPH to NADH. Evolution of enzymes without coenzymes. If enzymes require a co-enzyme, how does the coenzyme evolve? The most likely scenario is that enzymes can function initially without their coenzymes and later recruit the coenzyme, even if the catalyzed reaction may not be as efficient or as fast. Examples are Alcohol Dehydrogenase (coenzyme: NAD⁺), Lactate Dehydrogenase (NAD⁺), Glutathione Reductase (NADPH).
Drugs under prescription control are sent to pharmacies in multi-packs of unit packs or in bottles containing many hundreds of capsules. Typically a pharmacist prepares the final form of the unit pack or places a lower count of capsules in a small bottle for the customer. In a pharmacy, pharmacists are available to answer questions and to ensure that proper documentation is provided. Internet pharmacies mail the prescribed drugs to the customer; boxes or mailing envelopes are used. Child resistant packaging is often required on the unit packs; if requested, a pharmacist is allowed to put drugs in a bottle with easy-open features. Over-the-counter drugs are sold in independent or chain pharmacies, grocery stores, and diverse retail outlets. Usually the package needs to have all the usage information available. Packages often need to have tamper resistant features and child-resistant packaging. Usually the packaging and labeling of dietary supplements, homeopathic products, and folk medicines are not regulated. Some producers voluntarily follow the regulations for over-the-counter drugs or regional Pharmacopoeias.
Sources: en.wikipedia.org
4He* → n + 3He + 3.3 MeV (ratio=50%) 4He* → p + 3H + 4.0 MeV (ratio=50%) 4He* → 4He + γ + 24 MeV (ratio=10−6) Only about one in a million of the intermediaries take the third pathway, making its products very rare compared to the other paths. This result is consistent with the predictions of the Bohr model. If 1 watt (6.242 × 1018 eV/s) were produced from ~2.2575 × 1011 deuteron fusions per second, with the known branching ratios, the resulting neutrons and tritium (3H) would be easily measured. Some researchers reported detecting 4He but without the expected neutron or tritium production; such a result would require branching ratios strongly favouring the third pathway, with the actual rates of the first two pathways lower by at least five orders of magnitude than observations from other experiments, directly contradicting both theoretically predicted and observed branching probabilities. Those reports of 4He production did not include detection of gamma rays, which would require the third pathway to have been changed somehow so that gamma rays are no longer emitted. The known rate of the decay process together with the inter-atomic spacing in a metallic crystal makes heat transfer of the 24 MeV excess energy into the host metal lattice prior to the intermediary's decay inexplicable by conventional understandings of momentum and energy transfer, and even then there would be measurable levels of radiation. Also, experiments indicate that the ratios of deuterium fusion remain constant at different energies.
The classic symptom of keratoconus is the perception of multiple "ghost" images, known as monocular polyopia. This effect is most clearly seen with a high contrast field, such as a point of light on a dark background. Instead of seeing just one point, a person with keratoconus sees many images of the point, spread out in a chaotic pattern. This pattern does not typically change from day to day, but over time, it often takes on new forms. People also commonly notice streaking and flaring distortion around light sources. Some even notice the images moving relative to one another in time with their heartbeat. The predominant optical aberration of the eye in keratoconus is coma. The visual distortion experienced by the person comes from two sources, one being the irregular deformation of the surface of the cornea, and the other being scarring that occurs on its exposed highpoints. These factors act to form regions on the cornea that map an image to different locations on the retina. The effect can worsen in low light conditions, as the dark-adapted pupil dilates to expose more of the irregular surface of the cornea. Significant retinal layer thickness reduction is observed in keratoconus, especially in younger patients (<30 years).
A 2025 evidence summary for family physicians concluded that, in people with type 2 diabetes, weekly insulin icodec lowers hemoglobin A1c similarly to daily long-acting insulin glargine or degludec, while noting limited data in people or situations at higher risk for hypoglycemia.
The most important of these nuclei is the locus coeruleus, located in the pons. Outside the brain, norepinephrine is used as a neurotransmitter by sympathetic ganglia located near the spinal cord or in the abdomen, as well as Merkel cells located in the skin. It is also released directly into the bloodstream by the adrenal glands. Regardless of how and where it is released, norepinephrine acts on target cells by binding to and activating adrenergic receptors located on the cell surface. A variety of medically important drugs work by altering the actions of noradrenaline systems. Noradrenaline itself is widely used as an injectable drug for the treatment of critically low blood pressure. Stimulants often increase, enhance, or otherwise act as agonists of norepinephrine. Drugs such as cocaine and methylphenidate act as reuptake inhibitors of norepinephrine, as do some antidepressants, such as those in the SNRI class. One of the more notable drugs in the stimulant class is amphetamine, which acts as a dopamine and norepinephrine analog, reuptake inhibitor, as well as an agent that increases the amount of global catecholamine signaling throughout the nervous system by reversing transporters in the synapses. Beta blockers, which counter some of the effects of noradrenaline by blocking beta-adrenergic receptors, are sometimes used to treat glaucoma, migraines and a range of cardiovascular diseases.
=== Addition of translation-independent amino acids === Presence of a ribosome quality control protein Rqc2 is associated with mRNA-independent protein elongation. This elongation is a result of ribosomal addition (via tRNAs brought by Rqc2) of CAT tails: ribosomes extend the C-terminus of a stalled protein with random, translation-independent sequences of alanines and threonines.
Sources: en.wikipedia.org
冻融过程中冰晶形成与局部浓度升高会促使肽链发生界面吸附和聚集。聚集不仅降低有效含量，还会改变可见异物与不溶性微粒的计数结果。将溶液分装为单次使用的小体积等份可减少循环次数。
该方法依据疏水性差异分离主峰与相关杂质，对缺失序列、氧化产物和脱酰胺变体具有较好分辨能力。流动相中加入离子对试剂可改善峰形。紫外检测在肽键吸收区工作，灵敏度足以支持常规放行检验。
加速条件可以放大多数化学降解，但聚集与界面诱导的变化对容器、摇动和温度历史更敏感。某些固态转变在短时高温下不一定出现。因此实时稳定性数据仍不可替代，加速结果一般只作为趋势参考。
It is a synthetic analog of GLP-1 produced through medicinal chemistry to resist enzymatic degradation. The design goal was longer circulation than the native hormone.