freeze-thaw raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected 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.
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
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.
Apigenin (4′,5,7-trihydroxyflavone), found in many plants, is a flavone compound that is the aglycone of several naturally occurring glycosides. It is a yellow crystalline solid that has been used to dye wool. Apigenin is abundant in parsley, celery, celeriac, and chamomile flowers. It occurs in many fruits and vegetables, with the highest concentrations in dried and fresh parsley.
==== Prophecies and statements ==== In 2013, Bakker wrote Time Has Come: How to Prepare Now for Epic Events Ahead about end-time events. Bakker has changed his views on prosperity theology. In his 1980 book Eight Keys to Success, he stated, "God wants you to be happy, God wants you to be rich, God wants you to prosper." In his 1996 book, I Was Wrong, he admitted that the first time he actually read the Bible all the way through was in prison. Bakker also wrote that he realized that he had taken passages out of context and used them as prooftexts to support his prosperity theology. Bakker's revived show features a number of ministers who bill themselves as "prophets". He now says that "PTL" stands for "Prophets Talking Loud". In an October 2017 video, Bakker said that "God will punish those" who ridicule him; he has said that Hurricane Harvey was a judgment of God, and he blamed Hurricane Matthew on then-President Barack Obama. Bakker predicted that if then-President Donald Trump was impeached, Christians would begin a Second American Civil War. He compared the 2017 Washington train derailment to the sinking of the RMS Titanic and stated the Amtrak train derailment was a warning from God. He also claimed that he predicted the September 11 attacks of 2001, stating that he "saw 9/11 in 1999 before New Year's Eve" and that there would "be terrorism" and bombings in New York City and Washington, D.C. A few days after the Stoneman Douglas High School shooting, he stated that "God came to [him] in a dream...
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==== As prophylaxis against sexually transmitted infections ==== Doxycycline is used as post-exposure prophylaxis (PEP) to prevent certain sexually transmitted infections, known as doxycycline post-exposure prophylaxis (doxyPEP). A landmark randomized trial in San Francisco found that a single 200 mg dose of doxycycline taken within 72 hours after condomless sex reduced the overall incidence of bacterial STIs by approximately two-thirds among men who have sex with men (MSM) and transgender women, with reductions of 87–88% for chlamydia, 73–87% for syphilis, and 55% for gonorrhea. However, a separate trial found doxyPEP was not effective in cisgender women. In June 2024, the US Centers for Disease Control and Prevention (CDC) issued clinical guidelines recommending doxyPEP for MSM and transgender women with at least one bacterial STI in the prior 12 months. The Australasian Society for HIV Medicine issued a more cautious consensus statement recommending doxyPEP only for syphilis prevention in MSM, citing concerns that the risk of increasing antimicrobial resistance, especially in Neisseria gonorrhoeae, outweighed the benefits for other STIs. Use of doxyPEP has been associated with tetracycline resistance in N. gonorrhoeae.
Sources: en.wikipedia.org
Repeated bombing of Bremen in World War II resulted in the mass-production plants being moved to eastern Germany and General Government, with AGO Flugzeugwerke of Oschersleben as a major subcontractor for the Fw 190. Those plants used many foreign and forced labourers, and from 1944 also prisoners of war. Focke-Wulf's 100-acre (0.40 km2) plant at Marienburg produced approximately half of all Fw 190s and was bombed by the Eighth Air Force on 9 October 1943. Many Focke-Wulf workers, including Kurt Tank, worked at the Instituto Aerotécnico in Córdoba, Argentina between 1947 and 1955. Others, like Henrich Focke, went to Brazil's Department of Aerospace Science and Technology, helping Brazil's effort to build Embraer. Focke-Wulf began to make gliders in 1951, and in 1955, motorised planes. Focke-Wulf, Weserflug and Hamburger Flugzeugbau joined forces in 1961 to form the Entwicklungsring Nord (ERNO) to develop rockets. ITT Corporation, which had acquired a 25% stake in the company prior to the war, won $27 million in compensation in the 1960s for the damage that was inflicted on its share of the Focke-Wulf plant by WWII Allied bombing. Colonel Sosthenes Behn, Ludwig Roselius and Barbara Goette outfoxed Hitler in 1936 when he tried to have Roselius removed as a major stakeholder from Focke-Wulf A.G. and reconstitution followed resulting in the privatized company Focke-Wulf Flugzeugbau GmbH.
The monofunctional monomer, often referred to as a chain stopper, controls and limits the polymerization of bifunctional monomers because the growing polymer yields chain ends devoid of functional groups and therefore incapable of further reaction.
Moniz, in return, promised to send him a copy of his forthcoming monograph on leucotomy and urged him to purchase a leucotome from a French supplier. Upon receipt of Moniz's monograph, Freeman reviewed it anonymously for the Archives of Neurology and Psychiatry. Praising the text as one whose "importance can scarcely be overestimated", he summarised Moniz's rationale for the procedure as based on the fact that while no physical abnormality of cerebral cell bodies was observable in the mentally ill, their cellular interconnections may harbour a "fixation of certain patterns of relationship among various groups of cells" and that this resulted in obsessions, delusions and mental morbidity. While recognising that Moniz's thesis was inadequate, for Freeman it had the advantage of circumventing the search for diseased brain tissue in the mentally ill by instead suggesting that the problem was a functional one of the brain's internal wiring, where relief might be obtained by severing problematic mental circuits. In 1937, Freeman and Watts adapted Lima and Moniz's surgical procedure and created the Freeman-Watts technique, also known as the Freeman-Watts standard prefrontal lobotomy, which they styled the "precision method".
It is revealed at the 1991 Thanksgiving dinner episode that the absent Al has had a mistress for over 20 years, for which Bev eventually divorces him. Around this time Roseanne Barr was in a public battle with her real-life parents, claiming that both had physically and sexually abused her. Barr insisted that parental abuse be incorporated into the series storyline, so it is revealed that her father was physically abusive to both her and Jackie, who lived in fear of him for most of their childhood. Upon his death, Roseanne meets with his mistress, Joan, who is unaware of Al's abusive behavior, as he had led her to believe that Roseanne and Jackie were ungrateful daughters despite his doing so much for them. At Al's funeral, after privately reading him a list of the things she hates him doing to her and Jackie, Roseanne thanks her father for giving her his humorous nature.
==== Partially competitive ==== The mechanism of partially competitive inhibition is similar to that of non-competitive, except that the EIS complex has catalytic activity, which may be lower or even higher (partially competitive activation) than that of the enzyme–substrate (ES) complex. This inhibition typically displays a lower Vmax, but an unaffected Km value.
Sources: en.wikipedia.org
Smoking tobacco has serious negative effects on human health. Tobacco smoking is the greatest cause of preventable death globally. Half of tobacco smokers die from complications related to smoking. Active smokers are estimated to die an average of 10 years earlier than non-smokers. The World Health Organization estimates that, annually, more than 7 million people die from tobacco-related causes, including 1.6 million non-smokers due to passive smoking. It is further estimated to have caused 100 million deaths in the 20th century. Tobacco smoke contains over 70 chemicals, known as carcinogens, that cause cancer. It also contains nicotine, a highly addictive psychoactive drug. When tobacco is smoked, the nicotine causes physical and psychological dependency. Cigarettes sold in least developed countries have higher tar content and are less likely to be filtered, increasing vulnerability to tobacco smoking–related diseases in these regions. Tobacco use most commonly leads to diseases affecting the heart, liver, and lungs. Smoking is a major risk factor for several conditions, namely pneumonia, heart attacks, strokes, chronic obstructive pulmonary disease (COPD)—including emphysema and chronic bronchitis—and multiple cancers (particularly lung cancer, cancers of the larynx and mouth, bladder cancer, and pancreatic cancer). It is also responsible for peripheral arterial disease and high blood pressure. The effects vary depending on how frequently and for how many years a person smokes.
=== 25 April === According to RIA Novosti, T-14 Armata tanks were used to fire indirectly on Ukrainian positions but were yet to be deployed in "direct assault operations". The tanks were given extra protection and the crews underwent "combat coordination".
Although these are both aspects of earthworm activities the net effect is important to ascertain, in particular in the frame of organic matter disappearance linked to global warming. It seems that there is now a consensus about the prominent role of earthworms in carbon sequestration due to the fact that part of organic matter is mineralized at or near the soil surface while the major part is incorporated in the deep soil where it is stabilized by links with clay minerals.
=== Diabetic ketoacidosis (DKA) === Diabetic ketoacidosis (DKA) is one of the life-threatening severe complications of diabetes that demands immediate attention and intervention. It is considered a medical emergency and can affect both patients with T1D (type 1 diabetes) and T2D (type 2 diabetes), but it is more common in T1D. DKA results from significantly low insulin levels due to various factors including undiagnosed diabetes (people who did not know they have diabetes), missed or delayed doses, insufficient insulin administration, or undergoing physiological stress (e.g. infection, surgery, Stroke, or trauma). Due to insulin absence, it simply triggers the release of counter-regulatory hormones resulting in serious health complications. This release prompts excessive free fatty acids (FFAs) production as a result of the adipose tissue exhibiting heightened activity of hormone-sensitive lipase. Subsequently, the liver turns fatty acid to ketone bodies for fuel, a process known as ketosis, which causes Ketonemia (high ketone level in the blood) that decreases the blood's pH, leading to DKA. While periodic ketosis is normal, but can become a serious problem if sustained. These hormones can also induce hyperglycemia (high blood glucose) by stimulating gluconeogenesis thereby increasing the renal glucose output. In addition to the endogenous renal glucose produced by the kidneys. The condition of high circulating concentrations of ketone bodies and hyperglycemia leads to osmotic diuresis, characterized by the excessive presence of glucose and ketones in the urine.
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
Selank is a synthetic peptide made of seven amino acids. It is modeled on tuftsin, a natural tetrapeptide, with an added three-residue tail. It is not a small-molecule drug.