|
Hyperekplexia
Hyperekplexia (; "exaggerated surprise") is a neurological disorder characterized by a pronounced startle response to tactile or acoustic stimuli and an ensuing period of hypertonia. The hypertonia may be predominantly truncal, attenuated during sleep, or less prominent after one year of age. Classic hyperekplexia is caused by genetic mutations in a number of different genes, all of which play an important role in glycine neurotransmission. Glycine is used by the central nervous system as an inhibitory neurotransmitter. Hyperekplexia is generally classified as a genetic disease; some disorders can mimic the exaggerated startle of hyperekplexia. Signs and symptoms The three main signs of hyperekplexia are generalized stiffness, excessive startle response beginning at birth, and nocturnal myoclonus. Affected individuals are fully conscious during episodes of stiffness, which consist of forced closure of the eyes and an extension of the extremities followed by a period of generali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycine Receptor, Alpha 1
Glycine receptor subunit alpha-1 is a protein that in humans is encoded by the ''GLRA1'' gene. Function The inhibitory glycine receptor mediates postsynaptic inhibition in the spinal cord and other regions of the central nervous system. It is a pentameric receptor composed solely of alpha subunits. The GLRB gene encodes the alpha subunit of the receptor. Clinical significance Mutations in the gene have been associated with hyperekplexia, a neurologic syndrome associated with an exaggerated startle reaction. See also * Glycine receptor * Stiff person syndrome * Hyperekplexia Hyperekplexia (; "exaggerated surprise") is a neurological disorder characterized by a pronounced startle response to tactile or acoustic stimuli and an ensuing period of hypertonia. The hypertonia may be predominantly truncal, attenuated durin ... References Further reading * * * * * * * * * * * * * * * * * * External links * Ion channels {{membrane-protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GLRA1
Glycine receptor subunit alpha-1 is a protein that in humans is encoded by the ''GLRA1'' gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei .... Function The inhibitory glycine receptor mediates postsynaptic inhibition in the spinal cord and other regions of the central nervous system. It is a pentameric receptor composed solely of alpha subunits. The GLRB gene encodes the alpha subunit of the receptor. Clinical significance Mutations in the gene have been associated with hyperekplexia, a neurologic syndrome associated with an exaggerated startle reaction. See also * Glycine receptor * Stiff person syndrome * Hyperekplexia References Further reading * * * * * * * * * * * * * * * * * * External links * Ion channels {{membrane-protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SLC6A5
Sodium- and chloride-dependent glycine transporter 2, also known as glycine transporter 2 (GlyT2), is a protein that in humans is encoded by the ''SLC6A5'' gene. The glycine transporter 2 is a membrane protein which recaptures glycine, a major inhibitory transmitter in the spinal cord and brainstem. GlyT2 is a specific marker of glycinergic neurons and a member of the Na+ and Cl−-coupled transporter family SLC6. Glycine uptake mediated by GlyT2 is electrogenic, coupled to three Na+ and one Cl− (i.e. two positive charges per glycine). In humans, GlyT2 is encoded by the ''SLC6A5'' gene. Inactivation of GlyT2 in knockout mice is lethal during the second post-natal week as the absence of GlyT2 disrupts inhibitory transmission by reducing glycine release. Mutations in SLC6A5 gene are responsible for a presynaptic form of hyperekplexia, a genetic disease causing increased startle reflex. GlyT2 main physiological role is to recapture glycine released in the synaptic cleft and to ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GPHN
Gephyrin is a protein that in humans is encoded by the ''GPHN'' gene. This gene encodes a neuronal assembly protein that anchors inhibitory neurotransmitter receptors to the postsynaptic cytoskeleton via high affinity binding to a receptor subunit domain and tubulin dimers. In nonneuronal tissues, the encoded protein is also required for molybdenum cofactor biosynthesis. Mutations in this gene may be associated with the neurological condition hyperekplexia and also lead to molybdenum cofactor deficiency. Gene Numerous alternatively spliced transcript variants encoding different isoforms have been described; however, the full-length nature of all transcript variants is not currently known. The production of alternatively spliced variants is affected by noncoding regions within the gene. There are two major, very different variants among human populations in these regulatory regions termed "yin" and "yang".* Function Gephyrin is a 93kDa multi-functional protein that is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurotransmission
Neurotransmission (Latin: ''transmissio'' "passage, crossing" from ''transmittere'' "send, let through") is the process by which signaling molecules called neurotransmitters are released by the axon terminal of a neuron (the presynaptic neuron), and bind to and react with the receptors on the dendrites of another neuron (the postsynaptic neuron) a short distance away. Changes in the concentration of ions, such as Ca2+, Na+, K+, underlie both chemical and electrical activity in the process. The increase in calcium levels is essential and can be promoted by protons. A similar process occurs in retrograde neurotransmission, where the dendrites of the postsynaptic neuron release retrograde neurotransmitters (e.g., endocannabinoids; synthesized in response to a rise in intracellular calcium levels) that signal through receptors that are located on the axon terminal of the presynaptic neuron, mainly at GABAergic and glutamatergic synapses. Neurotransmission is regulated by severa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypertonia
Hypertonia is a term sometimes used synonymously with ''spasticity'' and ''rigidity'' in the literature surrounding damage to the central nervous system, namely upper motor neuron lesions. Impaired ability of damaged motor neurons to regulate descending pathways gives rise to disordered spinal reflexes, increased excitability of muscle spindles, and decreased synaptic inhibition. These consequences result in abnormally increased muscle tone of symptomatic muscles. Some authors suggest that the current definition for spasticity, the velocity-dependent overactivity of the stretch reflex, is not sufficient as it fails to take into account patients exhibiting increased muscle tone in the absence of stretch reflex over-activity. They instead suggest that "reversible hypertonia" is more appropriate and represents a treatable condition that is responsive to various therapy modalities like drug or physical therapy. Presentation Symptoms associated with central nervous systems diso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torso
The torso or trunk is an anatomical terminology, anatomical term for the central part, or the core (anatomy), core, of the body (biology), body of many animals (including human beings), from which the head, neck, limb (anatomy), limbs, tail and other appendages extend. The tetrapod torso — including that of a human body, human — is usually divided into the ''chest, thoracic'' segment (also known as the upper torso, where the forelimbs extend), the ''abdomen, abdominal'' segment (also known as the "mid-section" or "midriff"), and the ''pelvic'' and ''perineum, perineal'' segments (sometimes known together with the abdomen as the lower torso, where the hindlimbs extend). Anatomy Major organs In humans, most critical Organ (anatomy), organs, with the notable exception of the brain, are housed within the torso. In the upper chest, the heart and lungs are protected by the rib cage, and the abdomen contains most of the organs responsible for digestion: the stomach, which breaks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis). Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ult ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycine
Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (GGU, GGC, GGA, GGG). Glycine disrupts the formation of alpha-helices in secondary protein structure. Its small side chain causes it to favor random coils instead. Glycine is also an inhibitory neurotransmitter – interference with its release within the spinal cord (such as during a '' Clostridium tetani'' infection) can cause spastic paralysis due to uninhibited muscle contraction. It is the only achiral proteinogenic amino acid. It can fit into both hydrophilic and hydrophobic environments, due to its minimal side chain of only one hydrogen atom. History and etymology Glycine was discovered in 1820 by French chemist Henri Braconnot when he hydrolyzed gelatin by boiling it with sulfuric acid. He originally called it "sugar of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Startle Response
In animals, including humans, the startle response is a largely unconscious defensive response to sudden or threatening Stimulus (physiology), stimuli, such as sudden noise or sharp movement, and is associated with negative Affect (psychology), affect.Rammirez-Moreno, David. "A computational model for the modulation of the prepulse inhibition of the acoustic startle reflex". ''Biological Cybernetics'', 2012, p. 169 Usually the onset of the startle response is a startle reflex reaction. The startle reflex is a brainstem reflectory reaction (reflex) that serves to protect vulnerable parts, such as the back of the neck (whole-body startle) and the eyes (eyeblink) and Fight-or-flight response, facilitates escape from sudden stimuli. It is found across many different species, throughout all stages of life. A variety of responses may occur depending on the affected individual's emotional state, body posture, preparation for execution of a motor task, or other activities. The startle respo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Nervous System
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilateria, bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and Coelenterata, diploblasts. It is a structure composed of nervous tissue positioned along the Anatomical_terms_of_location#Rostral,_cranial,_and_caudal, rostral (nose end) to caudal (tail end) axis of the body and may have an enlarged section at the rostral end which is a brain. Only arthropods, cephalopods and vertebrates have a true brain, though precursor structures exist in onychophorans, gastropods and lancelets. The rest of this article exclusively discusses the vertebrate central nervous system, which is radically distinct from all other animals. Overview In vertebrates, the brain and spinal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
