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Blood–brain barrier

The blood–brain barrier is a selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from non-selectively crossing into the extracellular fluid of the central nervous system where neurons reside. The blood-brain barrier is formed by endothelial cells of the capillary wall, astrocyte end-feet ensheathing the capillary, pericytes embedded in the capillary basement membrane; this system allows the passage of some molecules by passive diffusion, as well as the selective transport of various nutrients, organic anions, macromolecules such as glucose and amino acids that are crucial to neural function. The blood-brain barrier restricts the passage of pathogens, the diffusion of solutes in the blood, large or hydrophilic molecules into the cerebrospinal fluid, while allowing the diffusion of hydrophobic molecules and small polar molecules. Cells of the barrier transport metabolic products such as glucose across the barrier using specific transport proteins.

Specialized brain structures participating in sensory and secretory integration within brain neural circuits — the circumventricular organs and choroid plexus — have permeable capillaries. The blood-brain barrier results from the selectivity of the tight junctions between the endothelial cells of brain capillaries, restricting the passage of solutes. At the interface between blood and the brain, endothelial cells are adjoined continuously by these tight junctions, which are composed of smaller subunits of transmembrane proteins, such as occludin, junctional adhesion molecule; each of these transmembrane proteins is anchored into the endothelial cells by another protein complex that includes tight junction protein 1 and associated proteins. The blood-brain barrier is composed of endothelial cells restricting passage of substances from the blood more selectively than endothelial cells of capillaries elsewhere in the body. Astrocyte cell projections called astrocytic feet surround the endothelial cells of the BBB, providing biochemical support to those cells.

The BBB is distinct from the quite similar blood-cerebrospinal fluid barrier, a function of the choroidal cells of the choroid plexus, from the blood-retinal barrier, which can be considered a part of the whole realm of such barriers. Several areas of the human brain are not on the brain side of the BBB; some examples of this include the circumventricular organs, the roof of the third and fourth ventricles, capillaries in the pineal gland on the roof of the diencephalon and the pineal gland. The pineal gland secretes the hormone melatonin "directly into the systemic circulation", thus melatonin is not affected by the blood-brain barrier; the blood-brain barrier appears to be functional by the time of birth. P-glycoprotein, a transporter, exists in the embryonal endothelium. Measurement of brain uptake of various blood-borne solutes showed that newborn endothelial cells were functionally similar to those in adults, indicating that a selective BBB is operative at birth; the blood-brain barrier acts to protect the brain from circulating pathogens.

Accordingly, blood-borne infections of the brain are rare. Infections of the brain that do occur are difficult to treat. Antibodies are too large to cross the blood-brain barrier, only certain antibiotics are able to pass. In some cases, a drug has to be administered directly into the cerebrospinal fluid where it can enter the brain by crossing the blood-cerebrospinal fluid barrier; the blood-brain barrier may become leaky in select neurological diseases, such as amyotrophic lateral sclerosis, brain trauma and edema, in systemic diseases, such as liver failure. The blood-brain barrier becomes more permeable during inflammation, allowing antibiotics and phagocytes to move across the BBB. However, this allows bacteria and viruses to infiltrate the blood-brain barrier. Examples of pathogens that can traverse the blood-brain barrier include Toxoplasma gondii which causes toxoplasmosis, spirochetes like Borrelia, Group B streptococci which causes meningitis in newborns, Treponema pallidum which causes syphilis.

Some of these harmful bacteria gain access by releasing cytotoxins like pneumolysin which have a direct toxic effect on brain microvascular endothelium and tight junctions. Circumventricular organs are individual structures located adjacent to the fourth ventricle or third ventricle in the brain, are characterized by dense capillary beds with permeable endothelial cells unlike those of the blood-brain barrier. Included among CVOs having permeable capillaries are the area postrema, subfornical organ, vascular organ of the lamina terminalis, median eminence, pineal gland, three lobes of the pituitary gland. Permeable capillaries of the sensory CVOs enable rapid detection of circulating signals in systemic blood, while those of the secretory CVOs facilitate transport of brain-derived signals into the circulating blood; the CVO permeable capillaries are the point of bidirectional blood-brain communication for neuroendocrine function. The border zones between brain tissue "behind" the blood-brain barrier and zones "open" to blood signals in certain CVOs contain specialized hybrid capillaries that are leakier than typical brain capillaries, but not as permeable as CVO capillaries.

Such zones exist at the border of the area postrema—nucleus tractus solitarii, median eminence—hypothalamic arcuate nucleus. These zones appear to function as rapid transit regions for brain structures involved in diverse neural circuits — like the NTS and arcuate nucleus — to re

Gállego (river)

The Gállego is a river in Aragon, one of the main tributaries of the Ebro River. It has a watershed of over 4,000 square kilometres, with a total length of 193.2 kilometres. The river has its source at 2,200 metres in Col d'Aneu, not far from the Col du Pourtalet, it flows in the Tena Valley through the municipalities of Sallent de Gállego and Biescas. Starting from Sabiñánigo it forms a wide elbow until Triste, from which it continues in its primitive north-south direction until flowing into the Ebro near Zaragoza; the main tributaries of the Gállego in its upper basin are the Aguas Limpias, Caldarés, Lana Mayor and Aurín. In the medium and lower basin, they include Guarga, Asabón and Sotón; the river's waters are subject to extensive regulation and derivation during its course, thus when it flows into the Ebro its discharge is just some 10 percent of its natural discharge. This river gives its name to the Alto Gállego comarca of Aragon. List of rivers of Spain Comarca Alto Gállego Rafting on the Gállego

Knockout rat

A knockout rat is a genetically engineered rat with a single gene turned off through a targeted mutation used for academic and pharmaceutical research. Knockout rats can mimic human diseases and are important tools for studying gene function and for drug discovery and development; the production of knockout rats was not economically or technically feasible until 2008. Technology developed through funding from the National Institutes of Health and work accomplished by the members of the Knock Out Rat Consortium led to cost-effective methods to create knockout rats; the importance of developing the rat as a more versatile tool for human health research is evidenced by the $120 million investment made by the NIH via the Rat Genome Sequencing Project Consortium, resulting in the draft sequence of a laboratory strain of the brown or Norway rat. Additional developments with zinc finger nuclease technology in 2009 led to the first knockout rat with targeted, germline-transmitted mutations. Knockout rat disease models for Parkinson's, Alzheimer's, diabetes using zinc-finger nuclease technology are being commercialized by SAGE Labs.

Mice and humans share all but 1% of each other's genes making rodents good model organisms for studying human gene function. Both mice and rats are small handled, have a short generation time, are genetically inbred. While mice have proven to be a useful rodent model and techniques have been developed for routine disruption of their genes, in many circumstances rats are considered a superior laboratory animal for studying and modeling human disease. Rats are physiologically more similar to humans. For example, rats have a heart rate more similar to that of humans, while mice have a heart rate five to ten times as fast, it is believed that the rat is a better model than the mouse for human cardiovascular disease, diabetes and many autoimmune, neurological and addiction disorders. In addition, rat models are superior to mouse models for testing the pharmacodynamics and toxicity of potential therapeutic compounds because the number and type of many of their detoxifying enzymes are similar to those in humans.

Their larger size makes rats more conducive to study by instrumentation, facilitates manipulation such as blood sampling, nerve conduction, performing surgeries. Techniques for genetic manipulation are available in the mouse, used to model human disease. Although published knockouts exist for 60% of mouse genes, a large majority of common human diseases do not have a knockout mouse model. Knockout rat models are an alternative to mice that may enable the creation of new gene disruptions that are unavailable in the mouse. Knockout rat models can complement existing transgenic mouse models. Comparing mouse and rat mutants can facilitate the distinction between rodent-specific and general mammalian phenotypes. Rat models have been used to advance many areas of medical research, including cardiovascular disease, psychiatric disorders, neural regeneration, transplantation, autoimmune disorders and wound & bone healing. While the completion of the rat genome sequence provides key information, how these diseases relate to gene function requires an efficient method to create knockout rat models in which specific genomic sequences are manipulated.

Most techniques for genetic manipulation, including random mutagenesis with a gene trap, gene knock-outs/knock-ins, conditional mutations, depend upon the culture and manipulation of embryonic stem cells. Rat ES cells were only isolated and no demonstration of gene modification in them has been reported. Many genetic manipulation techniques used in the mouse are not possible in the rat; until the commercial development of mobile DNA technology in 2007 and zinc-finger nuclease technology in 2009, there were only two technologies that could be used to produce rat models of human disease: cloning and chemical mutagenesis using N-ethyl-N-nitrosourea. Although cloning by somatic cell nuclear transfer could theoretically be used to create rats with specific mutations by mutating somatic cells, using these cells for SCNT, this approach has not been used to create knockout rats. One problem with this strategy is that SCNT is inefficient; the first published attempt had a success rate of less than 1%.

Alternatively, ENU mutagenesis is a common random mutagenesis gene knockout strategy in the mouse that can be used in the rat. ENU mutagenesis involves using a chemical, N-ethyl-N-nitrosourea, to create single base changes in the genome. ENU transfers its ethyl group to oxygen or nitrogen radicals in DNA, resulting in mis-pairing and base pair substitution. Mutant animals can be produced by injecting a male mouse with ENU, breeding with a wild type female to produce mutant offspring. ENU mutagenesis creates a high frequency of random mutations, with one base pair change in any given gene in every 200-700 gametes. Despite its high mutagenicity, the physical penetration of ENU is limited and only about 500 genes are mutated for each male and a small number of the total mutations have an observable phenotype. Thousands of mutations need to be created in a single animal in order to generate one novel phenotype. Despite recent improvements in ENU technology, mapping mutations responsible for a particular phenotype is difficult and time-consuming.

Neutral mutations must be separated from causative mutations, via extensive breed


Playboating is a discipline of whitewater kayaking or canoeing where people perform various technical moves in one place, as opposed to downriver whitewater canoeing or kayaking where the objective is to travel the length of a section of river. Specialised canoes or kayaks known as playboats are used, but any boat can be used for playing; the moves and tricks are similar to those performed by snowboarders, surfers or skaters, where the athlete completes spins, turns, etc. With modern playboats it is possible to get the kayak and the paddler airborne while performing tricks; the competitive side of playboating is known as freestyle kayaking. Playspots are stationary features on rivers, in particular standing waves, hydraulic jumps,'holes' and'stoppers', where water flows back on itself creating a retentive feature, or eddy lines. Basic moves consist of front- and back-surfing, spins through any of the three axes; the playboater aims to stay surfing the feature after performing each move. More complex moves are made up of combinations of these moves.

These moves are scored by the International Canoe Federation, are used in official competitions worldwide. These moves were more popular before short playboats were invented, but remain the foundation of several current moves. Ender An ender is performed by sinking the bow of the boat deep into swift moving water, causing the boat to go vertical. Popup A popup is an ender, followed by leaning back to cause the boat to pop up out of the water like a cork. Pirouette A pirouette is when the boater turns with the boat as the axis. Squirt A basic squirt is performed; as soon as the body crosses the eddyline, a back sweep is performed while dropping the upstream edge of the stern. The stern of the boat should sink, the boat will rotate in the direction of the currents. You can develop this into a cartwheel. Double pump This is the move at the beginning of a cartwheel making the boat go up on its side and on the front into a bow stall. Mystery Move The paddler submerges the kayak and themself. Front Surf A front surf involves remaining on a feature of the river without being washed downstream.

From this position, many moves can be initiated. Back Surf A back surf is identical to the front surf, but with the boat facing downstream; this is most accomplished by transitioning through a move such as a spin, cartwheel, or blunt. Back surfing is harder than front surfing. Side Surf A side surf is done with the boat oriented perpendicular to the current; the paddler must raise their upstream edge to maintain this position. This move is easier to learn because it is the natural position a kayak will move, due to its buoyancy if a wave or hole has any shape to it. Carving Carving involves moving forth across the face of a feature; this is accomplished by tilting the boat at an angle while using the paddle to press against the water near the downstream end of the boat. Carving may be aggressive, depending on the intended result. Carpet Roll / Window Shade The paddler catches an edge while surfing and flips over unintentionally no matter how much they claim they were attempting an orbit. Grind On a large wave the kayaker turns sideways into a side surf, but slips down the face of the wave to the trough or up the oncoming water.

Basic Spin Involves rotating the boat parallel to the surface of the water while surfing a feature. The rotation must be greater than 180 degrees to count as a spin. Performing a 180 degree spin is similar to beginning an aggressive carve, transitioning through a side surf, ending in a back surf. Clean Spins A clean spin involves using a single stroke to spin through multiple ends. Flatspin / Super Clean Spin A flatspin / super clean spin involves lifting the upstream edge of the boat from the water during the spin; this is accomplished by beginning the spin with a slight angle to the water. Shuvit A 180 degree spin a 180 degree spin back the way the paddler came from, it is considered less difficult than a 360 degree spin. Double Pump A double pump is the basic move to initiate, one end of the boat; the boater begins by putting the boat on edge, making a quick forward power stroke, leaning backwards. After this stroke, the boater leans forward, switches the blade from a forward to a back stroke at the stern and pushes down hard using the core muscles on the same paddle blade.

The boat should now be perpendicular to the surface of the water, with the bow down in the water and the stern up toward the sky. Basic Cartwheel A cartwheel is a move performed while surfing a hole or on flat water, in which the boat rotates perpendicular to the surface of the water; the paddler's torso functions as the axis. The move is initiated with a double pump, though on more powerful features little initiation will be necessary. Once vertical, the paddler continues the rotation; the paddle is used to press down on the water on the downstream side of the boat, alternating hands as the boat changes direction. Flatwheel A flatwheel is a cartwheel performed on flat water; the move is initiated with a double pump, but may

Poi Dog Pondering

Poi Dog Pondering is an American musical group, noted for its cross-pollination of diverse musical genres, including various forms of acoustic and electronic music. Founded in Hawaii in 1984 by Frank Orrall as a solo project. In 1985 Orrall formed the first line-up of PDP to perform its first concert; the band embarked on a yearlong Street Performance Busking tour across North America settling in Austin, Texas in 1987, where they recorded their first three albums. In 1992, the band relocated, this time to Chicago, where they began to incorporate Orchestral arrangements & elements of Electronic, House Music and Soul music into their Acoustic Rock style; the membership of Poi Dog Pondering has changed from album to album. During the Hawaii years, the band had the following lineup: Frank Orrall – Guitar, marimba, penny whistle Abra Moore – Guitar, accordion Sean CoffeyDrums John "el John" Nelson – Percussion Kalea Chapman – Guitar, vocals Jean Francois Berneron – Photographer, vocals, recorder Cliff Kamida – Guitar, harmonica Ted Cho – Mandolin, guitar Joe Espinda – Guitar, recording engineer Matt Miller - Bass, vocals During the Austin years, the band had the following lineup: Frank Orrall – guitar, tin flute, vocals Ted Cho – electric guitar, bass Dave Max Crawfordorgan, accordion Darren Hess – drum kit Bruce Hughes – bass, guitar John Nelsoncongas, tom-toms, background vocals Dick Ross – drum kit Adam Sultan – electric guitar, acoustic guitar, vocals Susan Voelzviolin, vocalsAdditionally, the records featured dozens of musicians credited as "Satellite Poi Members".

Most prominent amongst these satellite members were vocalists Abra Moore & Malford Milligan, sound artist Ellen Fullman, drummer Sean Coffey and turntable operator Ashton "DJ Cassanova" Irons. Beginning with that third album, 1992's Volo Volo, the band began to experiment with new musical styles, including incorporating DJ Cassanova into the line-up. Orrall's emerging interest in dance and house music led the band to relocate to Chicago in 1992, where it developed a loyal local following and was named best band by Chicago magazine in 1997 & "Best Pop and Rock Act" in the 2009 Chicago Readers Poll. From 1993 to 1999, the band recorded the albums "Pomegranate" & "Natural Thing" and performed live with the following members in the lineup: Frank Orrall – guitar, vocals Dave Max Crawford – keyboards, clavinet Paul Mertens – sax, flute Susan Voelz – violin Dag Juhlin – guitar Eddie Carlson – Bass Brent Olds – bass Tom Ray – Bass Nick Kitsos – Drums Steve Goulding – drums Leddie Garcia – Percussion Arlene Newson – backing vocals Kornell Hargrove – backing vocals Robert Cornelius – backing vocalsSatellite Members Brigid Murphy – Alto Saxophone Jason More – Berimbau Lloyd Brodnax King – Alto Flute Katherine Pisaro – Oboe From 1999 to 2013, the band had the following members in the lineup: Frank Orrall – vocals, piano, synth.

Vibes, samples, sequencing Susan Voelz – violin, vocals Paul Mertens – flute, clarinet Leddie Garcia – congas, ganzas, shakers, various percussion Kornell Hargrove – vocals Ron Hall – bass Rick Gehrenbeck – rhodes electric piano, organ, synthesizers Charlette Wortham – vocals Alison Chesleycello Carla Prather – vocals Tim Gant – piano, synthesizers John "El John" Nelson – Percussion, drums Earl A. Talbot – Drums Dan Leali – Drums Frank Orrall – vocals, piano, synth. Vibes, samples, sequencing Susan Voelz – violin, vocals Dave Max Crawford – organ, trumpet, flugelhorn, electric piano, synthesizer, theremin John Nelson – congas, drums, various percussion Ted Cho – Guitar, Mandolin Dag Juhlin – guitar Kornell Hargrove – vocals Ron Hall – bass Rick Gehrenbeck – rhodes electric piano, organ, synthesizers Charlette Wortham – vocals Robert Cornelius – vocals Carla Prather – vocals Ryan Murphy – Drums Paul Mertens – flute, clarinet Poi Dog Pondering PDP X 1 Poi Dog Pondering Soliloqui PDP X 2 8 Songs by Poi Dog Pondering PDP X 3 Poi Dog Pondering Dig PDP X 4 Hawaii to Texas Poi Dog Pondering Wishing Like a Mountain and Thinking Like the Sea Volo Volo Pomegranate Natural Thing In Seed Comes Fruit 7 Audio Love Letter Everybody's Got a Star Remnants of Summer Fruitless Vague Gropings in the Slip Stream Electrique Plummagram That's the Way Love Is Intermittent Transmissions from the SlipStream Liquid White Light Soul Sonic Orchestra Live at Metro Chicago Sweeping Up the Cutting Room Floor The Best of Poi Dog Pondering Song Seeds of 7 Four on the Floor - Dance Floor Rarities and Remixes: 1994-2018 Sweeping Up the Cutting Room Floor - Volume 2 Audio Visivo Live at Metro Chicago Official site Discography Their page on Allmusic Poi Dog Pondering group page on FaceBook Poi Dog Pondering MySpace page


XHFCY-FM is a radio station in Mérida, Yucatán, with transmitter at San Pedro Nohpat. Broadcasting on 105.9 FM, XHFCY is owned by Grupo Rivas and carries a contemporary music format known as Super Stereo. Rafael Rivas Franco and Julio Molina Font put XEFC-AM 1050 on air July 26, 1930. Rivas gave XEFC its callsign in honor of Felipe Carrillo Puerto, a former governor of the state, executed in 1924. Font sold his stake in the station, the concession, to Rivas in 1944. XEFC was the first station in what came to be known as Organización Radio Peninsular, which expanded to include additional Mérida and Yucatán radio stations and is now known as Grupo Rivas. XEFC moved to 1330 AM in the 1950s and slid to 1090 kHz in the early 2000s. On July 1, 2010, XHFCY-FM 105.9 signed on as part of the national plan to move most AM radio stations to FM. The added Y in the callsign allowed the avoidance of a callsign conflict with then-XHFC-FM, a community station in Michoacán