Cholesterol is an organic molecule. It is a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell membranes. Cholesterol serves as a precursor for the biosynthesis of steroid hormones, bile acid and vitamin D. Cholesterol is the principal sterol synthesized by all animals. In vertebrates, hepatic cells produce the greatest amounts, it is absent among prokaryotes, although there are some exceptions, such as Mycoplasma, which require cholesterol for growth. François Poulletier de la Salle first identified cholesterol in solid form in gallstones in 1769. However, it was not until 1815 that chemist Michel Eugène Chevreul named the compound "cholesterine". Cholesterol is essential for all animal life, with each cell capable of synthesizing it by way of a complex 37-step process; this begins with the mevalonate or HMG-CoA reductase pathway, the target of statin drugs, which encompasses the first 18 steps. This is followed by 19 additional steps to convert the resulting lanosterol into cholesterol.
A human male weighing 68 kg synthesizes about 1 gram of cholesterol per day, his body contains about 35 g contained within the cell membranes. Typical daily cholesterol dietary intake for a man in the United States is 307 mg. Most ingested cholesterol is esterified; the body compensates for absorption of ingested cholesterol by reducing its own cholesterol synthesis. For these reasons, cholesterol in food, seven to ten hours after ingestion, has little, if any effect on concentrations of cholesterol in the blood. However, during the first seven hours after ingestion of cholesterol, as absorbed fats are being distributed around the body within extracellular water by the various lipoproteins, the concentrations increase. Plants make cholesterol in small amounts. Plants manufacture phytosterols, which can compete with cholesterol for reabsorption in the intestinal tract, thus reducing cholesterol reabsorption; when intestinal lining cells absorb phytosterols, in place of cholesterol, they excrete the phytosterol molecules back into the GI tract, an important protective mechanism.
The intake of occurring phytosterols, which encompass plant sterols and stanols, ranges between ≈200–300 mg/day depending on eating habits. Specially designed vegetarian experimental diets have been produced yielding upwards of 700 mg/day. Cholesterol, given that it composes about 30% of all animal cell membranes, is required to build and maintain membranes and modulates membrane fluidity over the range of physiological temperatures; the hydroxyl group of each cholesterol molecule interacts with water molecules surrounding the membrane, as do the polar heads of the membrane phospholipids and sphingolipids, while the bulky steroid and the hydrocarbon chain are embedded in the membrane, alongside the nonpolar fatty-acid chain of the other lipids. Through the interaction with the phospholipid fatty-acid chains, cholesterol increases membrane packing, which both alters membrane fluidity and maintains membrane integrity so that animal cells do not need to build cell walls; the membrane remains stable and durable without being rigid, allowing animal cells to change shape and animals to move.
The structure of the tetracyclic ring of cholesterol contributes to the fluidity of the cell membrane, as the molecule is in a trans conformation making all but the side chain of cholesterol rigid and planar. In this structural role, cholesterol reduces the permeability of the plasma membrane to neutral solutes, hydrogen ions, sodium ions. Within the cell membrane, cholesterol functions in intracellular transport, cell signaling and nerve conduction. Cholesterol is essential for the structure and function of invaginated caveolae and clathrin-coated pits, including caveola-dependent and clathrin-dependent endocytosis; the role of cholesterol in endocytosis of these types can be investigated by using methyl beta cyclodextrin to remove cholesterol from the plasma membrane. Cholesterol regulates the biological process of substrate presentation and the enzymes that use substrate presentation as a mechanism of their activation. Is a well-defined example of an enzyme activated by substrate presentation.
The enzyme is palmitoylated causing the enzyme to traffic to cholesterol dependent lipid domains sometimes called "lipid rafts". The substrate of phospholipase D is phosphatidylcholine, unsaturated and is of low abundance in lipid rafts. PC localizes to the disordered region of the cell along with the polyunsaturated lipid phosphatidylinositol 4,5-bisphosphate. PLD2 has a PIP2 binding domain; when PIP2 concentration in the membrane increases, PLD2 leaves the cholesterol dependent domains and binds to PIP2 where it gains access to its substrate PC and commences catalysis based on substrate presentation. Cholesterol is implicated in cell signaling processes, assisting in the formation of lipid rafts in the plasma membrane, which brings receptor proteins in close proximity with high concentrations of second messenger molecules. In multiple layers and phospholipids, both electrical insulators, can facilitate speed of transmission of electrical impulses along nerve tissue. For many neuron fibers, a myelin sheath, rich in cholesterol since it is derived from compacted layers of Schwann cell membrane, provides insulation for more efficient conduction of impulses.
Demyelination (loss of some
The Aikido Schools of Ueshiba is a not-for-profit Aikido organization founded by Mitsugi Saotome Shihan upon moving from Japan to the United States in 1975. It is a federation of about 110 Dojos throughout North America; the ASU instructional syllabus includes open-hand training, defense versus weapons, weapons kata, defense against multiple attackers with and without weapons. As established by Saotome Shihan, ASU strives to have "no style", its members and instructors demonstrate a high level of individual expression in their technique and instruction; as reflected by Saotome Shihan's roles as senior instructor and Chief Weapons Instructor during his time at the Aikikai Hombu Dojo, training in ASU emphasizes martial spirit and awareness, significant weapons work and adaptability, natural movement and breathing, a sensitivity to natural action and biofeedback responses. These goals are exemplified in a quote by Saotome Shihan: "Aikido is not a factory; every student is unique. At its inception ASU was not formally connected to the Aikikai Foundation.
In 2016, ASU restructured and was formally recognized as an affiliated overseas organization member of the Aikikai Foundation. The Aikido Schools of Ueshiba is a 501 nonprofit organization, administered under a board of senior instructors. In addition to the actions of the board, ASU policy is reviewed and set by three standing committees: an Examination Committee, an Instructional Committee, an Advisory Committee of ASU instructors who are not board members. Saotome Shihan and Patty Saotome Sensei remain involved in ASU administration as Special Advisors to the ASU board. ASU's stated mission emphasizes the organization's special lineage to the founder of Aikido: "to preserve and disseminate the teachings and principles of Aikido, as transmitted by Morihei Ueshiba O Sensei to his direct disciple Mitsugi Saotome Shihan." Chief Instructor: Shihan Mitsugi Saotome * John Messores * Patty Saotome * Bill Gleason * Tres Hofmeister * George Ledyard * Wendy Whited * Charles Page * Charles Weber The Aiki Shrine was built by Saotome Shihan on his private property in Myakka City, Florida, to recreate and preserve the deep sense of spirituality and connection to nature that he recalled of the original Iwama Shrine from his years serving and living with the founder as personal live-in disciple.
In 2016, Saotome Shihan transferred ownership of the Aiki Shrine to ASU to preserve as a lasting and physical legacy, to unify future generations of ASU students and instructors through a living heritage and lineage to the spirit of O Sensei. The Ueshiba Juku is a special designation issued by Saotome Shihan to his personal disciples. Based on statements by Saotome Shihan, the Ueshiba Juku designation declares that the recipients are not only true deshi of Saotome Sensei and inheritors of his teachings, but are part of O Sensei's own school and pure lineage as only a true uchi deshi of O Sensei can recognize, it is denoted by a special kanji, worn on the left lapel of the recipient's dogi. Aikido Schools of Ueshiba
Lyn-Lake is a commercial district in south Minneapolis. At the core is the intersection of Lake Street and Lyndale Avenue from which Lyn-Lake takes its name; this is at the intersection of four Minneapolis neighborhoods: Whittier on the northeast, Lyndale on the southeast, Calhoun Area on the southwest, Lowry Hill East on the northwest. Most residents who consider themselves part of the "Lyn-Lake neighborhood" originate from the southeast corner of the Lyndale neighborhood. Lyn-Lake was branded by the Lyn-Lake Business Association in 1999. Locally, Lyn-Lake is known as being just east of the Uptown district of Minneapolis and considered an extension of Uptown. One of the oldest anchors was the It's Greek to Me restaurant on the northeast corner until it closed in 2019; the district contains ethnic restaurants, LGBT establishments, niche retail. North of Lyn-Lake is the Midtown Greenway pedestrian path. Regional access by car is through I-35W from the I-94 from the north. Open Streets Minneapolis and the Lyn Lake Street Festival are the signature events for the area and draw over 20,000 from the local community annually