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Ornithine Aminotransferase Deficiency
Ornithine aminotransferase deficiency (also known as gyrate atrophy of the choroid and retina) is an inborn error of ornithine metabolism, caused by decreased activity of the enzyme ornithine aminotransferase. Biochemically, it can be detected by elevated levels of ornithine in the blood. Clinically, it presents initially with poor night vision, which slowly progresses to total blindness. It is believed to be inherited in an autosomal recessive manner. Approximately 200 known cases have been reported in the literature. The incidence is highest in Finland, estimated at 1:50,000. Research suggests there can be some adverse effect on muscles and also the brain. The cause of this is somewhat unclear but may relate to very low levels of creatine often found in this population. Treatment may include vitamin B6, lysine or dramatic dietary change to minimise arginine from patients diet. Research has indicated that these treatments may be somewhat effective in lowering ornithine blood ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ornithine Aminotransferase
Ornithine aminotransferase (OAT) is an enzyme which is encoded in human by the OAT gene located on chromosome 10. The OAT involved in the ultimate formation of the non-essential amino acid proline from the amino acid ornithine. Ornithine aminotransferase forms the initial intermediate in this process. It catalyzes the reverse reaction as well, and is therefore essential in creating ornithine from the starting substrate proline. Structure The OAT gene encodes for a protein that is approximately 46 kDa in size. The OAT protein is expressed primarily in the liver and the kidney but also in the brain and the retina. The OAT protein is localized to the mitochondrion within the cells where it is expressed. The structure of the OAT protein has been resolved using X-ray crystallography and shows similarity to other subgroup 2 aminotransferases such as dialkyglucine decarboxylatse. The OAT protein functions as a dimer and each monomer consists of a large domain, which contributes mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ornithine
Ornithine is a non-proteinogenic α-amino acid that plays a role in the urea cycle. It is not incorporated into proteins during translation. Ornithine is abnormally accumulated in the body in ornithine transcarbamylase deficiency, a disorder of the urea cycle. The Moiety (chemistry), moiety derived from ornithine is called ornithyl. Role in urea cycle L-Ornithine is one of the products of the action of the enzyme arginase on L-arginine, creating urea. Therefore, ornithine is a central component of the urea cycle, which enables the disposal of excess nitrogen. Ornithine itself is recycled and, in a sense, acts as a catalyst. First, ammonia is converted into carbamoyl phosphate () by carbamoyl phosphate synthetase. Ornithine transcarbamylase then catalyzes the reaction between carbamoyl phosphate and ornithine to form citrulline and phosphate (Pi). Another amino group is contributed by aspartate, leading to the formation of arginine and the byproduct fumarate. The resulting arginine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blindness
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception. In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. The terms ''low vision'' and ''blindness'' are often used for levels of impairment which are difficult or impossible to correct and significantly impact daily life. In addition to the various permanent conditions, fleeting temporary vision impairment, amaurosis fugax, may occur, and may indicate serious medical problems. The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2%). Refractive errors include near-sightedness, far-sightedness, presbyopia, and astigmatism (eye), astigmatism. Cataracts are the most common cause of blindness. Other disorders that may cause visual problems include age-related macular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ornithine Translocase Deficiency
Ornithine translocase deficiency, also called hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome, is a rare autosomal recessive urea cycle disorder affecting the enzyme ornithine translocase, which causes ammonia to accumulate in the blood, a condition called hyperammonemia. Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The nervous system is especially sensitive to the effects of excess ammonia. Signs and symptoms Pathophysiology Mutations in '' SLC25A15'' cause ornithine translocase deficiency. Ornithine translocase deficiency belongs to a class of metabolic disorders referred to as urea cycle disorders. The urea cycle is a sequence of reactions that occurs in liver cells. This cycle processes excess nitrogen, generated when protein is used by the body, to make a compound called urea that is excreted by the kidneys. The ''SLC25A15'' gene provides instructions for making a protein called a mitocho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homocitrulline
L-Homocitrulline is an amino acid and can be detected in larger amounts in the urine of individuals with urea cycle disorders. At present, it is thought that the depletion of the ornithine supply causes the accumulation of carbamyl-phosphate in the urea cycle which may be responsible for the enhanced synthesis of homocitrulline and homoarginine. Both amino acids can be detected in urine. Amino acid analysis allows for the quantitative analysis of these amino acid metabolites in biological fluids such as urine or blood. Description Homocitrulline is one methylene group longer than citrulline, but similar in structure. The metabolite is generated from a lysine residue after lysine reacts with cyanate. Cyanate is present in the human body in equilibrium with urea. Under physiological conditions the urea concentration may be too low to allow extensive carbamylation. However, the conversion process leading to the formation of homocitrulline from lysine in proteins is known to occur in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urine
Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (males) or urethral meatus of the vulva (females) during urination. In other vertebrates, urine is excreted through the cloaca. Urine contains water-soluble by-products of Cell (biology), cellular metabolism that are rich in nitrogen and must be clearance (medicine), cleared from the Circulatory system, bloodstream, such as urea, uric acid and creatinine. A urinalysis can detect nitrogenous wastes of the mammalian body. Urine plays an important role in the earth's nitrogen cycle. In balanced ecosystems, urine fertilizes the soil and thus helps plants to grow. Therefore, Reuse of excreta, urine can be used as a fertilizer. Some animals use it to territory (animal)#Scent marking, mark their territories. Historically, aged or fermented urine (kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Plasma
Blood plasma is a light Amber (color), amber-colored liquid component of blood in which blood cells are absent, but which contains Blood protein, proteins and other constituents of whole blood in Suspension (chemistry), suspension. It makes up about 55% of the body's total blood volume. It is the Intravascular compartment, intravascular part of extracellular fluid (all body fluid outside cells). It is mostly water (up to 95% by volume), and contains important dissolved proteins (6–8%; e.g., serum albumins, globulins, and fibrinogen), glucose, clotting factors, electrolytes (, , , , , etc.), hormones, carbon dioxide (plasma being the main medium for excretory product transportation), and oxygen. It plays a vital role in an intravascular osmotic effect that keeps electrolyte concentration balanced and protects the body from infection and other blood-related disorders. Blood plasma can be separated from whole blood through blood fractionation, by adding an anticoagulant to a tube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life. Amino acids can be classified according to the locations of the core structural functional groups ( alpha- , beta- , gamma- amino acids, etc.); other categories relate to polarity, ionization, and side-chain group type ( aliphatic, acyclic, aromatic, polar, etc.). In the form of proteins, amino-acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life on Earth and its emergence. Amino acids are formally named by the IUPAC- IUBMB Joint Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Mutati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 10 (human)
Chromosome 10 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 10 spans about 134 million base pairs (the building material of DNA) and represents between 4 and 4.5 percent of the total DNA in cells. Genes Number of genes The following are some of the gene count estimates of human chromosome 10. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project ( CCDS) takes an extremely conservative strategy. So CCDS's gene number prediction represents a lower bound on the total number of human protein-coding genes. Gene list The following is a partial list of genes on human chromosome 10. For complete list, see the link in the infobox on the right. Diseases and disorders The following diseases are related to genes on chromos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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: protein-coding genes and non-coding genes. During gene expression (the synthesis of Gene product, RNA or protein from a gene), DNA is first transcription (biology), copied into RNA. RNA can be non-coding RNA, directly functional or be the intermediate protein biosynthesis, template for the synthesis of a protein. The transmission of genes to an organism's offspring, is the basis of the inheritance of phenotypic traits from one generation to the next. These genes make up different DNA sequences, together called a genotype, that is specific to every given individual, within the gene pool of the population (biology), population of a given species. The genotype, along with environmental and developmental factors, ultimately determines the phenotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allele
An allele is a variant of the sequence of nucleotides at a particular location, or Locus (genetics), locus, on a DNA molecule. Alleles can differ at a single position through Single-nucleotide polymorphism, single nucleotide polymorphisms (SNP), but they can also have insertions and deletions of up to several thousand base pairs. Most alleles observed result in little or no change in the function or amount of the gene product(s) they code or regulate for. However, sometimes different alleles can result in different observable phenotypic traits, such as different pigmentation. A notable example of this is Gregor Mendel's discovery that the white and purple flower colors in pea plants were the result of a single gene with two alleles. Nearly all multicellular organisms have two sets of chromosomes at some point in their biological life cycle; that is, they are diploid. For a given locus, if the two chromosomes contain the same allele, they, and the organism, are homozygous with re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
