A practical reference on Research chemical: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-05-04 and is reviewed periodically as new material appears.
Discussion of dihexa in online communities sometimes outpaces the scientific record. Anecdotal reports are difficult to verify and may not distinguish effects from placebo or expectation. The absence of approved human data means long-term risks remain unknown. Researchers continue to investigate related compounds and pathways. Open questions include whether animal findings translate to humans and which biological targets matter most. No consensus exists on these points. Current reviews emphasize the need for rigorous clinical research.
Most published work on dihexa consists of preclinical studies using cell cultures or rodents. Reports have described effects on synaptic connectivity and performance on cognitive tasks in some animal models. These findings are generally presented as preliminary and require independent replication. Study designs, doses, and outcome measures vary across experiments, which complicates direct comparison. No large controlled human trials have established efficacy or safety for any medical use. At present, the evidence base is limited.
Regulatory agencies have not approved dihexa as a prescription drug or supplement. In many countries it falls into a gray area when sold for laboratory research. Buyers may encounter products marketed for research use only, which are not intended for human consumption. Purity and identity can vary between suppliers and batches. Certificates of analysis and independent testing are often recommended for research materials. Documentation helps verify what a vial contains.
Human safety data are sparse. No widely accepted dosing regimen, long-term safety profile, or clinical efficacy endpoint has been established. Published animal results can suggest directions for further study, but species differences and study design limit direct translation. Open questions include bioavailability, blood-brain barrier penetration, metabolism, and whether observed effects arise from a single target or multiple pathways. Replication across independent laboratories remains an important benchmark for evaluating the strength of preclinical claims.
Most published reports on dihexa come from cell cultures and animal models. Studies have examined markers of synapse formation, dendritic spine density, and performance on learning tasks in rodents. Proposed mechanisms center on hepatocyte growth factor and its c-Met receptor, with additional attention to angiotensin IV-related pathways. These findings are experimental and have not been confirmed as clinical benefits in humans. The literature often uses different tasks and endpoints, which complicates direct comparison across studies.
Regulatory status differs by country, but dihexa is generally not approved as a therapeutic product. It is often sold as a research chemical, which means purity, labeling, and handling fall outside pharmaceutical drug standards. Some jurisdictions restrict the sale of peptides intended for human consumption. Researchers and suppliers may therefore face different legal requirements depending on location. Import rules and customs enforcement can also affect how such compounds move across borders.
| Property | Value | Notes |
|---|---|---|
| Development status | Preclinical research | No approved therapeutic indication has been established. |
| Human data | Limited or absent | Published controlled trials in people are not available. |
| Regulatory classification | Varies by country | Often treated as a research chemical rather than a medicine. |
| Common supply form | Lyophilized powder | Sold for laboratory use, not for human consumption. |
| Quality checks | Certificate of analysis; HPLC; mass spectrometry | Used to verify identity and purity in research settings. |
Regulatory and commercial contexts differ from clinical medicine. Dihexa is not approved as a drug by major agencies, and no published human trials establish its safety or efficacy. It is often sold as a research chemical labeled for laboratory use only. Suppliers may provide certificates of analysis, but purity and identity depend on the specific batch. Legal status varies by country and may treat such compounds as unapproved substances for human consumption.
Dihexa is a synthetic peptidomimetic derived from angiotensin IV, a naturally occurring peptide fragment. It was created as a research compound to explore central nervous system signaling rather than as an approved therapeutic. Early work described it as a small, orally available molecule in rodent studies. Its structure combines tyrosine, isoleucine, and aminohexanoic acid components with a hexanoic acid cap. The compound is commonly referred to by the research code PNB-0408.
Development of dihexa followed from studies on angiotensin IV analogs and their effects on learning and memory. Researchers sought compounds with improved metabolic stability and brain penetration compared with natural peptides. In preclinical reports, dihexa was associated with changes in synaptic connectivity and performance on spatial tasks. These findings generated interest in its potential as a cognitive research tool. The work remains largely preclinical, and independent replication has been limited.
Dihexa occupies an uncertain regulatory space in many countries. It is not generally listed as an approved therapeutic, and some jurisdictions may treat it as a research chemical, a compounded substance, or an unapproved new drug depending on claims and distribution. Importation can be restricted, and suppliers may require documentation that the material is for laboratory research only. Quality and labeling vary, so buyers should request analytical data, verify lot numbers, and understand local rules. These factors make sourcing and compliance part of the practical context around dihexa.
Lyophilized dihexa is typically stored as a dry powder at or below minus twenty degrees Celsius. Cooler temperatures slow degradation, and desiccant protection limits moisture uptake. Repeated temperature cycling can accelerate breakdown, so aliquoting before storage is common in laboratory practice. Solutions are generally less stable than dry powder and are often kept cold, protected from light, and used within a defined period. Specific stability data for dihexa are limited, and handling recommendations often follow general peptide guidelines rather than compound-specific studies.
Identity and purity are usually assessed with reverse-phase high-performance liquid chromatography and mass spectrometry. These methods can separate related impurities and confirm molecular mass, but they do not by themselves establish biological activity. Certificate of analysis documents may report purity as a percentage by area, yet the exact meaning can vary between laboratories. Independent testing can check for residual solvents, counterions, or microbial contamination when relevant. For research use, matching analytical records to a specific lot helps trace experimental variability.
Chemically, dihexa belongs to a broader group of angiotensin IV analogs. Researchers have modified the natural peptide to alter stability, binding, or distribution. Such changes can affect how the molecule behaves in experiments. The parent peptide angiotensin IV is involved in various physiological processes, but the modified analog is not identical to it. Public summaries sometimes blur the distinction between the natural fragment and the synthetic research compound. This distinction matters when interpreting study results.
Dihexa is a synthetic peptide that has been examined in laboratory and animal research. Its design is based on angiotensin IV, a naturally occurring peptide fragment produced in the body. The short name dihexa appears in scientific papers and online discussions, while the full chemical name describes a modified peptide chain. It is not a vitamin, mineral, or plant-derived compound. Suppliers typically present it as a research chemical rather than an approved medicine.
The full name often given is N-hexanoic-Tyr-Ile-(6)-aminohexanoic amide. This name indicates a chain containing tyrosine, isoleucine, and a six-carbon amino acid derivative. Databases list a CAS Registry Number and a molecular formula for the compound. The peptide is small compared with proteins, and its structure allows it to be studied in cell cultures and animal models. Exact identity depends on the supplier's synthesis and purification process. Minor impurities can remain after synthesis.
The angiotensin IV connection places dihexa in a family of short peptides studied for effects on central nervous system signaling. Angiotensin IV itself is a metabolite of angiotensin II, and analogs have been explored in cardiovascular and neurological research. Dihexa differs from the natural peptide through structural modifications intended to alter stability and receptor interactions. Published descriptions sometimes call it a hepatocyte growth factor mimetic, although that label reflects proposed activity rather than a confirmed clinical mechanism.
Identity checks for dihexa usually rely on mass spectrometry and chromatographic purity analysis. A lyophilized powder is the common supplied form, and it may appear as a white to off-white solid. Aqueous solubility is limited, so laboratory work often uses an organic solvent such as dimethyl sulfoxide to prepare stock solutions. Because the peptide is not a standard pharmaceutical product, exact specifications can vary between suppliers. Certificates of analysis may accompany a batch, but they are not equivalent to regulatory approval.
Dihexa is a synthetic peptide whose structure is modeled on angiotensin IV. Its chemical name often appears as N-hexanoic-Tyr-Ile-(6)-aminohexanoic amide, though vendor and publication naming can differ. The molecule combines a short amino acid sequence with a hexanoic acid group and an amide terminus. It is classed as a small research peptide rather than a conventional drug. Databases may list it under several synonyms, so matching names are important when comparing sources.
A variety of contractors are involved in the production, management, and distribution of UGRs and their contents, including (as of 2023) ABC Ventures, AmeriQual, Atlantic, Chef Minute Meals, Club Tex, Envision, Inc., Epic Foods, Gossner Foods, Hershey, HOIST, LC Industries, Nex-Xos, OhSix, Oregon Freeze Dry, Sterling Foods, Sopakco, Valley Foods, Werling Meats, and Wornick. More than 60,000 UGRs are produced each year. UGRs are supplied by the DLA's Operational Rations Division. UGRs, like other rations, cannot be sold to individuals, and are only supplied or sold to the U.S. military, the DoD, the federal government, government employee commissaries, government contractors (if their contract specifically permits such purchases), foreign governments with authorized contractual relationships, and civilians as humanitarian aid.
==== Off-chip incubation ==== Droplets containing cells can be stored off-chip in PTFE tubing for up to several days while maintaining cell viability and allowing for reinjection onto another device for analysis. Evaporation of aqueous and oil-based fluids has been reported with droplet storage in PTFE tubing, so for storage longer than several days, glass capillaries are also used. Finally, following formation in a microfluidic device, droplets may also be guided through a system of capillaries and tubing leading to a syringe. Droplets can be incubated in the syringe and then directly injected onto another chip for further manipulation or detection and analysis.
=== Current and resistance === The resistance of the filament is temperature dependent. The cold resistance of tungsten-filament lamps is about 1⁄15 the resistance when operating. For example, a 100-watt, 120-volt lamp has a resistance of 144 ohms when lit, but the cold resistance is much lower (about 9.5 ohms). Since incandescent lamps are resistive loads, simple phase-control TRIAC dimmers can be used to control brightness. Electrical contacts may carry a "T" rating symbol indicating that they are designed to control circuits with the high inrush current characteristic of tungsten lamps. For a 100-watt, 120-volt general-service lamp, the current stabilizes in about 0.10 seconds, and the lamp reaches 90% of its full brightness after about 0.13 seconds.
== Carboxyl radical == The carboxyl radical, •COOH, only exists briefly. The acid dissociation constant of •COOH has been measured using electron paramagnetic resonance spectroscopy. The carboxyl group tends to dimerise to form oxalic acid.
until the general election after next), with the government's long-term options remaining completely open; Clarke threatened to resign if this formula were departed from. Heseltine had opposed a referendum on euro membership when Thatcher proposed it in 1990. Clarke, writing in 2016 after the Brexit Referendum, comments that he and Heseltine later agreed that they had separately decided to give way because of the pressure Major was under, and that the referendum pledge "was the biggest single mistake" of their careers, giving "legitimacy" to such a device. Heseltine made several visits to Manchester in the aftermath of the IRA bomb on 15 June 1996 – he won the praise of opposition politicians for cutting red tape to arrange remedial measures. However, Crick recounts complaints about his aloofness from small shopkeepers, and Crick comments that he seemed to have lost the common touch which he had displayed in Liverpool in the early 1980s. In 1996 Heseltine was also one of the more hawkish ministers in urging non-cooperation with the European Community over the beef ban. However, after press speculation in December 1996 that he might abandon the government's "wait and see" policy on the euro in the hope of winning Eurosceptic votes, he took to the airwaves – in apparent unison with Clarke – to insist that the government retained a free choice as to whether or not to join, angering Eurosceptics.
Sources: en.wikipedia.org
== Reducing agent == DTT is a reducing agent; once oxidized, it forms a stable six-membered ring with an internal disulfide bond. It has a redox potential of −0.33 V at pH 7. The reduction of a typical disulfide bond proceeds by two sequential thiol-disulfide exchange reactions and is illustrated below. The reduction usually does not stop at the mixed-disulfide species because the second thiol of DTT has a high propensity to close the ring, forming oxidized DTT and leaving behind a reduced disulfide bond. The reducing power of DTT is limited to pH values above 7, since only the negatively charged thiolate form -S− is reactive (the protonated thiol form -SH is not); the pKa of the thiol groups is 9.2 and 10.1.
== Select publications == Müller, Thomas; Badu-Tawiah, Abraham; Cooks, R. Graham (2012). "Accelerated Carbon-Carbon Bond-Forming Reactions in Preparative Electrospray". Angewandte Chemie International Edition. 51 (47): 11832–11835. doi:10.1002/anie.201206632. ISSN 1521-3773. PMID 23042619. Badu-Tawiah, Abraham K.; Eberlin, Livia S.; Ouyang, Zheng; Cooks, R. Graham (2016). "Faculty Opinions recommendation of Chemical aspects of the extractive methods of ambient ionization mass spectrometry". Annual Review of Physical Chemistry. 64: 481–505. doi:10.1146/annurev-physchem-040412-110026. PMID 23331308. Damon, Deidre E.; Davis, Kathryn M.; Moreira, Camila R.; Capone, Patricia; Cruttenden, Riley; Badu-Tawiah, Abraham K. (10 February 2016). "Direct Biofluid Analysis Using Hydrophobic Paper Spray Mass Spectrometry". Analytical Chemistry. 88 (3): 1878–1884. doi:10.1021/acs.analchem.5b04278.s001. PMID 26730614.
Originally a Russian production, all in Russian with subtitles, produced by Maciej Drygas 15 October High Anxiety, about lifts and the required extensive technology of tall office buildings; Canary Wharf Tower (One Canada Square) had 50 floors with 36 lifts, which could travel up to 13.5 mph; Jim Fortune of Lerch Bates; novelist Philip Kerr; Otis Elevators alarm response centre of Farmington, Connecticut, which dealt with trapped passengers - it took about 20 minutes to rescue people; the Otis Test Tower, at Bristol in Connecticut, which had 29 floors and 11 lifts; architect Ken Yeang of Malaysia, known for his tall buildings; Gary Faltin of Otis; in the distant past, due to ropes, only goods were carried by lifts; in 1853 Elisha Otis invented a safety system for lifts, via a governor cable; only once have steel lift cables snapped, on 28 July 1945, in the 1945 Empire State Building B-25 crash after being lost in fog, severing the lift governor cable; if the cable snapped, due to the lift being balanced only after about nine people were in a lift, the lift would go upwards; on 12 August 1995, in the Empire State Building, a lift did go upwards, to be trapped at the 80th floor; the Woolworth Building, with 57 floors and 26 lifts, which could travel up to 10 mph - it was the world's tallest building from 1911 to 1930; engineer William Sheeran of Otis; medical doctor Rollin Stott, of the Linear Motion Laboratory of the Defence Research Agency (DERA) Centre for Human Sciences in north-east Hampshire; the feelings in the stomach, often sensed in a lift, comes from a pulse of adrenaline; Convent of Sacred Heart, with six floors; Nicole Fenchel was phobic of lifts; Doreen Powell of White Plains Hospital; the express lift, for the observation platform, in Tower 2 of the former World Trade Center had a journey time of 58 seconds; the former WTC had the world's second and third tallest office buildings; Tower 1 had 110 floors, being 417 metres high, with 96 lifts that could travel up to 15 mph; 70,000 people worked in the former WTC; people should not have to wait for a lift for no more than 30 seconds; Roger Howkins of Arup in London; 200 Vesey Street, known as Three World Financial Center, with 51 floors and 39 lifts, that could travel up to 14 mph; the former WTC was the first building to introduce the sky lobby design, with interspersed lifts; Robert DiChiara, assistant director of the former WTC; engineer Bruce Powell of Otis; Argentine architect, César Pelli, who designed One Canada Square of Canary Wharf; control systems of lifts anticipated demand; but there was a dark and menacing side to travel by lifts - Detectives Kevin Dineen and Lisa McClean of the NYPD Elevator Squad, at Carver Houses in the East Village, Manhattan, and how criminals could isolate victims; local youths and children would travel on top of the elevators for momentary thrills; the New York Marriott Marquis hotel, with 49 floors and 12 elevators, which could travel up to 15 mph; the Petronas Towers in Malaysia, with 88 floors, and 76 lifts, that could travel up to 16 mph, to be completed by 1997; lift ropes could go up to 600 metres, at the extreme most; new lifts would be powered by tubular linear motors or AC induction motors; 600 lifts with these new motors were operating in Japan; Yebisu Garden Place in Ebisu, Shibuya in Tokyo, where linear motors powered the lift counterweight; the Nishi-Shinjuku district in Shinjuku, Tokyo; many tall buildings were being built in Japan; Riverside Sumida Center, of Tokyo, built in 1994; the Yokohama Landmark Tower, with 70 floors, in Japan, built in 1993; Mitsubishi Electric had the world's fastest lifts, up to 28 mph; Junichi Sato of Mitsubishi, who said that he thought that Japanese people valued well-made products, and only trusted manufacturers too, whereas he thought that Americans and Europeans merely wanted functional products, whether good or not; the proposed enormous 800 metre Millennium Tower (Tokyo) for Tokyo Bay, with 150 floors, which was never built, but the Gherkin (30 St Mary Axe) was built instead; architect Andrew Miller of Foster Asia; there were twenty buildings over 60 floors being built; the Chinese economy was growing by 15% per year, and was Mitsubishi's biggest customer; the Century Tower (Tokyo), built in 1991, with 21 floors, with 14 lifts, that could travel up to 11 mph; lift technology had allowed Western business to prosper, but now it was superfluous for Western business. Narrated by Paul McGann, produced by Elizabeth Allen, directed by Gary Johnstone, made by Diverse Productions 22 October DNA in the Dock, an Equinox Special that was an update on the Incredible Evidence episode on 28 December 1994; The murder of 15-year-old Claire Hood, last seen on 19 January 1995, where 2,100 men had their DNA tested; her body was found in Cath Cobb Woods the next day; Sir Alec Jeffreys claimed that he could tell anyone apart; Timothy Wilson Spencer was the first person to be executed, with DNA evidence, on 27 April 1994, having committed murder in 1988; DCI Stuart Lewis, who worked on the Claire Hood investigation, who believed that her killer lived nearby - her killer lived 100 yards away; the United Kingdom National DNA Database began earlier in 1995, and in six months, 60,000 DNA specimens were recorded, and the database was intended to have 5 million specimens; an investigation of Orchid Cellmark, part of ICI, found that errors in correlation of specimens were made; California police gave test specimens to Cellmark, and errors were found, which Cellmark attributed to cross-contamination; Donald Findlay and a Scottish rape investigation in Largs, North Ayrshire, in 1987; former policeman Brian Kelly, and his wrongful conviction, for six years, serving four of them, for rape on 30 November 1989, through DNA evidence alone - DNA testing would later change in 1990, where crime scene DNA specimens were kept apart; Kary Mullis, who invented the PCR test in 1983, receiving the 1993 Nobel Prize in Chemistry, and knew about errors in DNA genetic testing; David Werrett of the Forensic Science Service, who set up the UK national DNA database in Birmingham, which deployed the PCR method - the more reliable Second Generation Multiplex Plus would be later introduced in 1999; Don Dovaston, later the deputy chief of Derbyshire Constabulary, which was the first police force to identify suspects through the UK DNA database; the Metropolitan Police had its own DNA database; Larry Mueller, population geneticist at the UCI School of Biological Sciences. Produced by David Poyser, directed by Hilary Lawson, made by TVF 5 November Kaboom!, the explosives engineer Sidney Alford; Controlled Demolition, Inc., founded by Jack Loizeaux; Rev Ron Lancaster, originally from Huddersfield, who founded Kimbolton Fireworks in 1964, when a chemistry teacher at Kimbolton School; in 1847 Ascanio Sobrero of Italy discovered nitroglycerin - nitroglycerin is the main component of dynamite; a detonation occurs at supersonic speed; Semtex was developed in Czechoslovakia in the 1960s; Ballistite, made from nitroglycerin and discovered in 1887, is the propellant for guns. Joint-production with NOVA and WGBH. Shown on Nova on 14 January 1997 12 November Avalanche, avalanches kill around two hundred people a year, with 120 of those in the Alps; Swiss physicist Othmar Buser of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), who developed a database of avalanches; Bruce Tremper; Doug Fesler; powder snow avalanches can reach 150 mph; Laurent Buisson. Narrated by Heather Couper, made by Pioneer Productions with Discovery Networks 19 November God only Knows, about how some physicists see theology being explained through physics, such as Frank J. Tipler of Tulane University and his book The Physics of Immortality; George Johnson (writer) and book titles; Lewis Wolpert and how there was no evidence for God in the external world; David Finley of the National Radio Astronomy Observatory; religious writer Karen Armstrong, author of A History of God; Brazilian physicist Marcelo Gleiser; physicist Leon M. Lederman; Russell Stannard and physics before the big bang; the KTeV experiment at Fermilab, which looked at kaons, and Vivian O'Dell; Rev John Polkinghorne, former professor of Mathematical Physics at the University of Cambridge. Narrated by Bill Paterson, produced by Nicolas Kent, directed by Peter Webber 26 November Gloria's Toxic Death, about the death of Gloria Ramirez in California on 19 February 1994; a nurse, who took a blood sample from her, passed out from inhaling an unknown vapour coming from the blood sample; few episodes of Doctor Who had such a bizarre and unbelievable storyline; blood tests from the nurses revealed a lowering of the enzyme cholinesterase, which in other cases is linked to organophosphate poisoning; the Lawrence Livermore National Laboratory proposed a connection to dimethyl sulfoxide (DMSO) that had combined with oxygen given in the hospital to make dimethyl sulfate; the conditions of the hospital were repeated in a test, and the results underwent gas chromatography–mass spectrometry by Yolanda de Miguel at Department of Chemistry, Imperial College London. Narrated by Neil Pearson, directed by Tim Shawcross, produced by Geoff Deehan, made by Union Pictures with Discovery Communications 3 December On Jupiter, about the large gravitational effect that Jupiter has on the solar system; if the mass of Jupiter was thirty times bigger, the heat in its centre could sustain nuclear reactions, and it could become a star, maybe a brown dwarf; Gene Shoemaker of the Lowell Observatory and Palomar Observatory; Galileo Galilei discovered Jupiter's moons, Io, Europa, Ganymede (the largest moon in the solar system), and Callisto, on 7 January 1610; Heidi Hammel of MIT; Galileo (spacecraft), built at JPL and Ames in the 1980s, being planned to have launched in 1982, arrived at Jupiter on 7 December 1995; Torrence Johnson of JPL; Jim Scotti of the Spacewatch project at Kitt Peak National Observatory; Brian G. Marsden of the Central Bureau for Astronomical Telegrams; Vicki Meadows of the Anglo-Australian Telescope; Imke de Pater of the W. M. Keck Observatory on Mauna Kea; David Morrison (astrophysicist) of NASA Ames. Narrated by John Hurt, directed by Richard Smith, made by Pioneer Productions and the Discovery Channel 10 December Designing Dream Machines, about product innovation and product design of food processors and a reinvented motorbike by the Seymour-Powell design agency and its designer Nick Talbot, with the management team of Tefal UK and its managing director and a design by 43-year-old Dick Powell, and a possible new design of the ubiquitous 125CC BSA Bantam motorbike for MZ Motorrad- und Zweiradwerk of Germany by 42-year-old Richard Seymour; the 59 Club; Leigh Martin of the defunct Comet (closed in December 2012). Narrated by Marilyn Milgrom, directed by Richard Burke, produced by Richard Reisz. TV6 went on to make the six-part series Better by Design 17 December It Runs on Water, about the field commonly known as fringe science, where physicist Frank Close was sceptical if not broadly dismissive, stating that 300 years of science could not be overruled, but a professor of Aeronautics Paul Csysz of Saint Louis University mentioned that he thought some people in science were often unquestioning of their lifelong-held beliefs, and nervous of anyone trying to do so; an invention in Moscow was looked at by American physicist Harold E. Puthoff; Stanley Meyer's water fuel cell; NASA's propulsion research at Lewis Research Center in Cleveland, Ohio; it ends with Sir Arthur C. Clarke and Requiem (Mozart). Directed by Lawrence Simanowitz, produced and narrated by William Woollard, made by InCA Productions with Discovery Communications 20 December Do Vampire Bats have Friends?, an Equinox Special about whether animals have consciousness; zoologist Prof John Krebs, Baron Krebs, and whether animals had human-like sentience; biologist Gerald Wilkinson of the University of Maryland, and research, over five years, into relationships of vampire bats with other types of animals, and found food sharing between hungry vampire bats; zoologist Miriam Rothschild; psychologist Cecilia Heyes of UCL and self-perception of chimpanzees; zoologist Bernd Heinrich of the University of Vermont, and puzzle-solving of raven birds; zoologist Benjamin Beck of The National Zoo, and the apparent deployment of tools by animals; Ian Farquhar, and foxhunting, and whether foxes realise their predicament, and the Duke of Beaufort's Hunt in Gloucestershire; biologist Sir Patrick Bateson of the University of Cambridge, sensation of pain in animals, and the Animals (Scientific Procedures) Act 1986, which defined protected animals, that did not cover the octopus, but due to research by the Universities Federation for Animal Welfare (UFAW); Prof Peter Boyle and Martin Wells, and a 1993 amendment added the octopus; Prof Daniel Dennett of Tufts University, and how snakes think; psychologist Irene Pepper berg, of the University of Arizona, and an African Grey parrot called Alex, who has been talking for 18 years; the horse Clever Hans; Robert Seyfarth (scientist) and Dorothy Cheney (scientist), and their work on baboon warning calls and grunts, in Kenya. Narrated by Andrew Sachs, directed by Christopher Sykes, made by Christopher Sykes Productions
==== Activity-based Profiling ==== To achieve functional degradomics, the enzymatic activity of proteases must be analyzed. Methods have been developed to distinguish the proteolytic activity of different enzymes in biological samples and separate active proteases from their inactive forms, namely zymogen precursors and those proteases bound by inhibitors. Two techniques are activity-based probes (ABPs) and Proteolytic Signature Peptides (PSPs). ABP molecules serve as probes to irreversibly bind only to active proteases and ignore their zymogen precursors and inhibited proteases. Placing a reactive group and a recognizable tag feature on the same molecule using a linker moiety gives an ABP molecule its structure. The reactive molecule, designed after protease inhibitor mechanisms, lends ABPs their specificity towards targeting active proteases. Once bound, the reactive group acts much like an irreversible inhibitor to the protease. Depending on the nature of the tag moiety, the ABP-protease complex can then be visualized or retrieved from biological samples for further studies of localization and quantification. Limitations including difficult production, specificity, stability, and toxicity hamper ABP development but these probes have proved useful in revealing protease biological activity and remain a promising avenue in degradomic technology. PSPs do not depend on targeting active proteases with tagged compounds but rather on quantitative proteomics using stable isotope labeled standard peptides.
==== Reproducibility ==== In 1989, after Fleischmann and Pons had made their claims, many research groups tried to reproduce the Fleischmann-Pons experiment, without success. A few other research groups, however, reported successful reproductions of cold fusion during this time. In July 1989, an Indian group from the Bhabha Atomic Research Centre (P. K. Iyengar and M. Srinivasan) and in October 1989, John Bockris' group from Texas A&M University reported on the creation of tritium. In December 1990, professor Richard Oriani of the University of Minnesota reported excess heat. Groups that did report successes found that some of their cells were producing the effect, while other cells that were built exactly the same and used the same materials were not. Researchers who continued to work on the topic have claimed over the years that many successful replications had been made, but still had problems getting reliable replications. Reproducibility is one of the main principles of the scientific method, and its lack led most physicists to believe that the few positive reports could be attributed to experimental error. The DOE 2004 report said among its conclusions and recommendations:
Sources: en.wikipedia.org
Published human trials are lacking. Most evidence comes from laboratory and animal studies. Therefore, human benefits and risks are not established.
Rules differ by country and by how the product is labeled. Research chemicals are often sold for laboratory use only. Buyers should check local regulations before ordering.
Some animal studies have examined cognitive outcomes, which has led to online interest. These results do not prove cognitive enhancement in people. The term nootropic is not a regulatory category.
Published human clinical trial data are limited or absent. Most available evidence comes from laboratory and animal studies. Human safety and efficacy remain unresolved.