This is a working overview of lyophilized, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-26. Anything still debated is marked as such rather than presented as settled.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
Full fat cottage cheese is 78% water, 12% protein, 5% carbohydrates, and 4% fat (table). In a reference amount of 100 g (3.5 oz), full fat cottage cheese supplies 103 calories of food energy, and is a rich source (20% or more of the Daily Value, DV) of vitamin B12 (28% DV) and a moderate source of phosphorus and sodium (12-15% DV, table). Cottage cheese is safe to eat during pregnancy, unlike some cheese products that are not recommended. Other than supplying nutrients, there is little evidence that consuming cottage cheese provides any direct health effects.
== Biochemistry == DTPA is more effective than EDTA to deactivate redox-active metal ions such as Fe(II)/(III), Mn(II)/(IV) and Cu(I)/(II) perpetuating oxidative damages induced in cells by superoxide and hydrogen peroxide. DTPA is also used in bioassays involving redox-active metal ions.
Almost all proteins that are destined to the secretory pathway have a sequence consisting of 5-30 hydrophobic amino acids on the N-terminus, which is commonly referred to as the signal peptide, signal sequence or leader peptide. Signal peptides form alpha-helical structures. Proteins that contain such signals are destined for either extra-cellular secretion, the plasma membrane, the lumen or membrane of either the (ER), Golgi or endosomes. Certain membrane-bound proteins are targeted to the secretory pathway by their first transmembrane domain, which resembles a typical signal peptide. In prokaryotes, signal peptides direct the newly synthesized protein to the SecYEG protein-conducting channel, which is present in the plasma membrane. A homologous system exists in eukaryotes, where the signal peptide directs the newly synthesized protein to the Sec61 channel, which shares structural and sequence similarity with SecYEG, but is present in the endoplasmic reticulum. Both the SecYEG and Sec61 channels are commonly referred to as the translocon, and transit through this channel is known as translocation. While secreted proteins are threaded through the channel, transmembrane domains may diffuse across a lateral gate in the translocon to partition into the surrounding membrane.
Acquired progressive lymphangioma (benign lymphangioendothelioma) Acral fibrokeratoma (acquired digital fibrokeratoma, acquired periungual fibrokeratoma) Acrochordon (cutaneous papilloma, cutaneous tag, fibroepithelial polyp, fibroma molluscum, fibroma pendulum, papilloma colli, skin tag, soft fibroma, Templeton skin tag) Adenoma sebaceum Adult type of generalized eruption of cutaneous mastocytosis African cutaneous Kaposi sarcoma African lymphadenopathic Kaposi sarcoma Aggressive infantile fibromatosis AIDS-associated Kaposi sarcoma Ainhum (bankokerend, dactylolysis spontanea, sukhapakla) Angiofibroma Angiokeratoma Angiokeratoma of Fordyce (angiokeratoma of the scrotum and vulva) Angiokeratoma of Mibelli (Mibelli's angiokeratoma, telangiectatic warts) Angioleiomyoma (vascular leiomyoma) Angiolipoleiomyoma Angiolipoma Angioma serpiginosum Angiosarcoma Aponeurotic fibroma (calcifying aponeurotic fibroma, juvenile aponeurotic fibroma) Atypical fibroxanthoma Benign lipoblastomatosis (embryonic lipoma) Buschke–Ollendorff syndrome (dermatofibrosis lenticularis disseminata) Capillary aneurysms Carcinoid Cellular angiofibroma Cherry angioma (De Morgan spot, senile angioma) Chondrodermatitis nodularis chronica helicis (chondrodermatitis nodularis helicis) Chondroid lipoma Chordoma Classic Kaposi sarcoma Collagenous fibroma (desmoplastic fibroblastoma) Composite hemangioendothelioma Connective tissue nevus (collagenoma, elastoma, shagreen patch) Cutaneous endometriosis Cutaneous meningioma (heterotopic meningeal tissue, rudimentary meningocele) Cutaneous myelofibrosis Cutaneous myxoma Cutis marmorata telangiectatica congenita (congenital generalized phlebectasia, Van Lohuizen syndrome) Dermal dendrocyte hamartoma Dermatofibroma (benign fibrous histiocytoma, dermal dendrocytoma, fibrous dermatofibroma, fibrous histiocytoma, fibroma simplex, histiocytoma, nodular subepidermal fibrosis, sclerosing hemangioma) Dermatofibrosarcoma protuberans Desmoid tumor Diffuse cutaneous mastocytosis Diffuse infantile fibromatosis Dupuytren's contracture (Dupuytren's diathesis, Dupuytren's disease, palmar fibromatosis) Eccrine angiomatous hamartoma Elastofibroma dorsi Endovascular papillary angioendothelioma (Dabska tumor, Dabska-type hemangioendothelioma, hobnail hemangioendothelioma, malignant endovascular papillary angioendothelioma, papillary intralymphatic angioendothelioma) Epithelioid cell histiocytoma Epithelioid hemangioendothelioma Epithelioid sarcoma Erythrodermic mastocytosis Extraskeletal chondroma (chondroma of soft parts) Familial myxovascular fibromas Fascial hernia Fibroma of tendon sheath Fibromatosis colli (sternomastoid tumor of infancy) Fibrous hamartoma of infancy Fibrous papule of the nose (benign solitary fibrous papule, fibrous papule of the face) Folded skin with scarring (Michelin tire baby syndrome) Fordyce's spot (Fordyce's disease) Ganglion cyst Ganglioneuroma Gardner fibroma Genital leiomyoma (dartoic leiomyoma) Giant cell fibroblastoma Giant cell tumor of the tendon sheath (giant cell synovioma, localized nodular tenosynovitis, pigmented villonodular synovitis) Glomeruloid hemangioma Glomus tumor (glomangioma, solid glomus tumor, solitary glomus tumor) Granular cell tumor (Abrikossoff's tumor, Abrikossov's tumor, granular cell myoblastoma, granular cell nerve sheath tumor, granular cell schwannoma) Hamartoma Hemangiopericytoma Hemangiosarcoma Hibernoma (fetal lipoma, lipoma of embryonic fat, lipoma of immature adipose tissue) Hypertrophic scar Immunosuppression-associated Kaposi sarcoma Infantile digital fibromatosis (inclusion body fibromatosis, infantile digital myofibroblastoma, Reye tumor) Infantile hemangiopericytoma (congenital hemangiopericytoma) Infantile myofibromatosis (congenital generalized fibromatosis, congenital multicentric fibromatosis) Infantile systemic hyalinosis (juvenile systemic hyalinosis) Intradermal spindle cell lipoma Intravascular papillary endothelial hyperplasia (Masson's hemangio-endotheliome vegetant intravasculaire, Masson's lesion, Masson's pseudoangiosarcoma, Masson's tumor, papillary endothelial hyperplasia) Juvenile hyaline fibromatosis (fibromatosis hyalinica multiplex juvenilis, Murray–Puretic–Drescher syndrome) Kaposiform hemangioendothelioma (infantile kaposiform hemangioendothelioma) Kasabach–Merritt syndrome (hemangioma with thrombocytopenia) Keloid (Keloidal scar) Keratinizing metaplasia Keratocyst Klippel–Trenaunay syndrome (angioosteohypertrophy syndrome, hemangiectatic hypertrophy) Knuckle pads (heloderma) Leiomyosarcoma Lipoma Liposarcoma (atypical lipoma, atypical lipomatous tumor) Lymphangiectasis (lymphangioma) Lymphangiomatosis Malignant fibrous histiocytoma Malignant peripheral nerve sheath tumor (malignant schwannoma, neurofibrosarcoma, neurosarcoma) Mast cell sarcoma Meningocele Metastatic carcinoma Microvenular hemangioma (microcapillary hemangioma) Midline nevus flammeus (angel's kiss, salmon patch) Multifocal lymphangioendotheliomatosis (congenital cutaneovisceral angiomatosis with thrombocytopenia, multifocal lymphangioendotheliomatosis with thrombocytopenia) Multinucleate cell angiohistocytoma Multiple cutaneous and uterine leiomyomatosis syndrome (leiomyomatosis cutis et uteri, multiple leiomyomatosis, Reed's syndrome) Multiple cutaneous leiomyoma (pilar leiomyoma) Neural fibrolipoma Neuroblastoma (infantile neuroblastoma, neuroepithelioma) Neuroma cutis Neurothekeoma (bizarre cutaneous neurofibroma, cutaneous lobular neuromyxoma, myxoma of the nerve sheath, myxomatous perineurioma, nerve sheath myxoma) Nevus flammeus (capillary malformation, port-wine stain) Nevus flammeus nuchae (stork bite) Nevus lipomatosus superficialis (nevus lipomatosis of Hoffman and Zurhelle) Nevus oligemicus Nodular fasciitis (nodular pseudosarcomatous fasciits, pseudosarcomatous fasciitis, subcutaneous pseudosarcomatous fibromatosis) Oral submucous fibrosis Pachydermodactyly Palisaded encapsulated neuroma Paraneoplastic syndrome Pearly penile papules (hirsuties coronae glandis, hirsutoid papillomas) Peyronie's disease (induratio penis plastica) Phakomatosis pigmentovascularis Piloleiomyoma Plantar fibromatosis (Ledderhose's disease) Pleomorphic fibroma Pleomorphic lipoma Plexiform fibrohistiocytic tumor Porokeratotic eccrine ostial and dermal duct nevus Progressive nodular histiocytoma Proliferating angioendotheliomatosis Prominent inferior labial artery Pseudo-ainhum
=== Environmental influence === It has been suggested that differences in penis size between individuals are caused not only by genetics, but also by environmental factors such as culture, diet and chemical or pollution exposure. Endocrine disruption resulting from chemical exposure has been linked to genital deformation in both sexes (among many other problems). Chemicals from both synthetic (e.g., pesticides, anti-bacterial triclosan, plasticizers for plastics) and natural (e.g., chemicals found in tea tree oil and lavender oil) sources have been linked to various degrees of endocrine disruption. Both PCBs and the plasticizer DEHP have been associated with smaller penis size. DEHP metabolites measured from the urine of pregnant women have been significantly associated with the decreased penis width, shorter anogenital distance and the incomplete descent of testicles of their newborn sons, replicating effects identified in animals. According to a 2008 study published by the US National Library of Medicine, approximately 25% of US women have phthalate levels similar to those observed in animals. Penile size may decrease as a result of some hormonal therapy combined with external beam radiation therapy. In addition, some estrogen-based fertility drugs like diethylstilbestrol (DES) have been linked to genital abnormalities or a smaller than normal penis (microphallus).
Sources: en.wikipedia.org
Otherwise, the carbonyl branch is homologous between the two domains and consists of the reduction of another molecule of CO2 to a carbonyl residue bound to an enzyme, catalyzed by the CO dehydrogenase/acetyl-CoA synthase. This key enzyme is also the catalyst for the formation of acetyl-CoA starting from the products of the previous reactions, the methyl and the carbonyl residues. This carbon fixation pathway requires only one molecule of ATP for the production of one molecule of pyruvate, which makes this process one of the main choice for chemolithoautotrophs limited in energy and living in anaerobic conditions.
However, they are not true benign neoplasms (denoted by suffix ~oma), which are similar in appearance but very rare in the mouth. Fibrous epulis are fibroepithelial polyps located only on the gingivae. Pyogenic granuloma and pregnancy epulis are both vascular rather than fibrous epulides with more dilated blood vessels making them appear darker pink or red in colour, and soft. They may develop more fibrous as they mature. The pregnancy variant only appears in pregnancy, usually due to plaque and should resolve with better oral hygiene and at the end of the pregnancy if not. Pyogenic granuloma may occur elsewhere in the mouth such as the tongue and lips, but are not therefore epulides. Giant cell epulis, also known as peripheral giant cell granuloma, are like fibrous epulis and occur at the anterior interdental margin, the gum between the teeth at the front. They are more common in females. They are often soft round and deep red to purplish blue. It is important they are investigated to make are they are not true giant cell granuloma. Papilliary hyperplasia of the palate, or epulis fissaratum/denture-induced hyperplasia. The cause may be unknown, but there is an association with ill-fitting dentures resulting in irritation to the mucosa, usually by overextended flange, and with poor denture or oral hygiene. Oral thrush can be present but is not thought to be the cause.
== Epidemiology == Myocardial infarction is a common presentation of coronary artery disease. The World Health Organization estimated in 2004, that 12.2% of worldwide deaths were from ischemic heart disease; with it being the leading cause of death in high- or middle-income countries and second only to lower respiratory infections in lower-income countries. Worldwide, more than 3 million people have STEMIs and 4 million have NSTEMIs a year. STEMIs occur about twice as often in men as women. Rates of death from ischemic heart disease (IHD) have slowed or declined in most high-income countries, although cardiovascular disease still accounted for one in three of all deaths in the US in 2008. For example, rates of death from cardiovascular disease have decreased almost a third between 2001 and 2011 in the United States. In contrast, IHD is becoming a more common cause of death in the developing world. For example, in India, IHD had become the leading cause of death by 2004, accounting for 1.46 million deaths (14% of total deaths) and deaths due to IHD were expected to double during 1985–2015. Globally, disability adjusted life years (DALYs) lost to ischemic heart disease are predicted to account for 5.5% of total DALYs in 2030, making it the second-most-important cause of disability (after unipolar depressive disorder), as well as the leading cause of death by this date.
=== Solid phases === Helium remains liquid down to absolute zero at atmospheric pressure, but it freezes at high pressure. Solid helium requires a temperature of 1–1.5 K (about −272 °C or −457 °F) at about 25 bar (2.5 MPa) of pressure. It is often hard to distinguish solid from liquid helium since the refractive index of the two phases are nearly the same. The solid has a sharp melting point and has a crystalline structure, but it is highly compressible; applying pressure in a laboratory can decrease its volume by more than 30%. With a bulk modulus of about 27 MPa it is ~100 times more compressible than water. Solid helium has a density of 0.214±0.006 g/cm3 at 1.15 K and 6.7 MPa (66 atm); the projected density at 0 K and 2.5 MPa (25 atm) is 0.187±0.009 g/cm3. At higher temperatures, helium will solidify with sufficient pressure. At room temperature, this requires about 11,600 MPa (114,000 atm). Helium-4 and helium-3 both form several crystalline solid phases, all requiring at least 25 bar. They both form an α phase, which has a hexagonal close-packed (hcp) crystal structure, a β phase, which is face-centered cubic (fcc), and a γ phase, which is body-centered cubic (bcc).
These include the lymph nodes (where the highest lymphocyte concentration is found), the spleen, the thymus, and the tonsils. Lymphocytes are initially generated in the bone marrow. The lymphoid organs also contain other cell types, such as stromal cells for support. Lymphoid tissue is also associated with mucosas such as mucosa-associated lymphoid tissue (MALT). These vessels carry lymph throughout the body, passing through numerous lymph nodes, which filter out unwanted materials such as bacteria and damaged cells. Lymph then passes into much larger lymph vessels known as lymph ducts. The right lymphatic duct drains the right side of the region, and the much larger left lymphatic duct, known as the thoracic duct, drains the left side of the body. The ducts empty into the subclavian veins to return to the bloodstream. Lymph is moved through the system by muscle contractions. In some vertebrates, a lymph heart is present that pumps the lymph to the veins. The lymphatic system was first described in the 17th century independently by Olaus Rudbeck and Thomas Bartholin.
Sources: en.wikipedia.org
==== Premenstrual dysphoric disorder ==== BPD is a psychiatric condition distinguishable from premenstrual dysphoric disorder (PMDD), despite some symptom overlap. BPD affects individuals persistently across all stages of the menstrual cycle, unlike PMDD, which is confined to the luteal phase and ends with menstruation. While PMDD, affecting 3–8% of women, includes mood swings, irritability, and anxiety tied to the menstrual cycle, BPD presents a broader, constant emotional and behavioral challenge irrespective of hormonal changes.
The cement production process is responsible for nearly 8% (2018) of global CO2 emissions, which includes heating raw materials in a cement kiln by fuel combustion and release of CO2 stored in the calcium carbonate (the calcination process). Its hydrated products, such as concrete, gradually reabsorb atmospheric CO2 (carbonation process), compensating for approximately 30% of the initial CO2 emissions. silicon dioxide
parietina, XPH1 is continuously expressed, unlike in non-lichenized fungi, where hydrophobins appear only at specific stages. Laboratory cultures of the mycobiont grown without its photobiont fail to produce XPH1, indicating that its synthesis depends on symbiosis. The hydrophobin layer also enhances desiccation resistance by repelling excess moisture and preventing prolonged saturation, allowing the lichen to recover quickly from dehydration. This is especially critical in exposed habitats with frequent wet-dry cycles. The hydrophobin layer may aid air pollution tolerance, particularly heavy metal resistance, by creating a protective barrier that reduces fungal exposure to toxic particulates. This may explain why X. parietina thrives in urban and industrial environments where other lichens struggle.
== History == Patellamide A was first isolated in 1981 from the tunicate L. patella collected from the reefs of Korror Island, Palau Islands. L. patella has been a rich source of peptide natural products. Aside from the patellamides, the lissoclinamides, ulicyclamide, ulithiacyclamide and ascidiacyclamide were all isolated from L. patella. The absolute stereochemistry was later determined by X-ray crystallography.
Over the years, multiple synthesizers have been developed to assist with automated synthesis, including the Chemspeed Accelerator (SLT106, SLT II, ASW2000, SwingSLT, Autoplant A100, and SLT100), the Symyx system, and Freeslate ScPPR. Recently, researchers have investigated the optimization of these methods for controlled/living radical polymerization (CLRP), which faces issues with oxygen intolerance. This research has led to the development of oxygen-tolerant CLRP, including with the use of enzyme degassing of RAFT (Enz-RAFT), atom-transfer radical (ATRP) that possesses tolerance to air, and photoinduced electron/energy transfer–RAFT (PET–RAFT) polymerization. Through the use of liquid-handling robots, Tamasi et al. demonstrated the use of automated synthesis with executing multi-step procedures, enabling the reactions to investigate more elaborate schemes, such as with scale and complexity. Lee Cronin and his team have developed a modular synthesis machine called the chemputer which uses a dedicated programming language for chemical synthesis.
Sources: en.wikipedia.org
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
Intranasal administration predominates in both animal and human research because it avoids hepatic first-pass metabolism. Injectable and intraperitoneal routes appear in animal work mainly for comparison.