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Citrullinemia
Citrullinemia is an autosomal recessive urea cycle disorder that causes ammonia and other toxic substances to accumulate in the blood.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. . Two forms of citrullinemia have been described, both having different signs and symptoms, and are caused by mutations in different genes. Citrullinemia belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of chemical reactions taking place in the liver. These reactions process excess nitrogen, generated when protein is used for energy by the body, to make urea, which is excreted by the kidneys. Diagnosis Type I Type I citrullinemia (, also known as classic citrullinemia) usually becomes evident in the first few days of life. Affected infants typically appear normal at birth, but as ammonia builds up in the body, they develop a lack of energy (lethargy), poor feeding, vomiting, seizures, and loss of cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citrullinemia Type I
Citrullinemia type I (CTLN1), also known as arginosuccinate synthetase deficiency, is a rare disease caused by a deficiency in argininosuccinate synthetase, an enzyme involved in excreting excess nitrogen from the body. There are mild and severe forms of the disease, which is one of the urea cycle disorders. Signs and symptoms Signs and symptoms of CTLN1 in infants are caused by increasing levels of ammonia in the blood and cerebrospinal fluid and include excessive vomiting, anorexia, refusal to eat, irritability, increased intracranial pressure, and worsening lethargy, seizures, hypotonia, respiratory distress, hepatomegaly, and cerebral edema. These symptoms appear within days of birth in the more severe forms of the disease with complete deficiency of the enzyme. As ammonia accumulates further, the affected infant may enter a hyperammonemic coma, which indicates neurological damage and can cause developmental delays, cognitive disabilities, cerebral palsy, hypertonia, sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argininosuccinate Synthetase
Argininosuccinate synthase or synthetase (ASS; ) is an enzyme that catalyzes the synthesis of argininosuccinate from citrulline and aspartate. In humans, argininosuccinate synthase is encoded by the '' ASS gene'' located on chromosome 9. ASS is responsible for the third step of the urea cycle and one of the reactions of the citrulline-NO cycle. Expression The expressed ASS gene is at least 65 kb in length, including at least 12 introns. In humans, ''ASS'' is expressed mostly in the cells of the liver and kidney. Mechanism In the first step of the catalyzed reaction, citrulline attacks the α-phosphate of ATP to form citrulline adenylate, a reactive intermediate. The attachment of AMP to the ureido (urea-like) group on citrulline activates the carbonyl center for subsequent nucleophilic attack. This activation facilitates the second step, in which the α-amino group of aspartate attacks the ureido group. Attack by aspartate is the rate-limiting step of the reaction. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASS (gene)
Argininosuccinate synthase or synthetase (ASS; ) is an enzyme that catalyzes the synthesis of argininosuccinate from citrulline and aspartate. In humans, argininosuccinate synthase is encoded by the '' ASS gene'' located on chromosome 9. ASS is responsible for the third step of the urea cycle and one of the reactions of the citrulline-NO cycle. Expression The expressed ASS gene is at least 65 kb in length, including at least 12 introns. In humans, ''ASS'' is expressed mostly in the cells of the liver and kidney. Mechanism In the first step of the catalyzed reaction, citrulline attacks the α-phosphate of ATP to form citrulline adenylate, a reactive intermediate. The attachment of AMP to the ureido (urea-like) group on citrulline activates the carbonyl center for subsequent nucleophilic attack. This activation facilitates the second step, in which the α-amino group of aspartate attacks the ureido group. Attack by aspartate is the rate-limiting step of the reacti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Urea Cycle
The urea cycle (also known as the ornithine cycle) is a cycle of Biochemistry, biochemical reactions that produces urea (NH2)2CO from ammonia (NH3). Animals that use this cycle, mainly amphibians and mammals, are called ureotelic. The urea cycle converts highly toxic ammonia to urea for excretion. This cycle was the first metabolic cycle to be discovered (Hans Adolf Krebs, Hans Krebs and Kurt Henseleit, 1932), five years before the discovery of the TCA cycle. This cycle was described in more detail later on by Ratner and Cohen. The urea cycle takes place primarily in the liver and, to a lesser extent, in the kidneys. Function Amino acid catabolism results in waste ammonia. All animals need a way to excrete this product. Most Aquatic animal, aquatic organisms, or Metabolic waste, ammonotelic organisms, excrete ammonia without converting it. Organisms that cannot easily and safely remove nitrogen as ammonia convert it to a less toxic substance, such as urea, via the urea cycle, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citrulline
The organic compound citrulline is an α-amino acid. Its name is derived from ''citrullus'', the Latin word for watermelon. Although named and described by gastroenterologists since the late 19th century, it was first isolated from watermelon in 1914 by Japanese researchers Yotaro Koga and Ryo OdakeEarly references spell Ryo Odake's name as ''Ryo Othake''. and further codified by Mitsunori Wada of Tokyo Imperial University in 1930. It has the formula H2NC(O)NH(CH2)3CH(NH2)CO2H. It is a key intermediate in the urea cycle, the pathway by which mammals excrete ammonia by converting it into urea. Citrulline is also produced as a byproduct of the enzymatic production of nitric oxide from the amino acid arginine, catalyzed by nitric oxide synthase. Biosynthesis Citrulline can be derived from: * from arginine via nitric oxide synthase, as a byproduct of the production of nitric oxide for signaling purposes * from ornithine through the breakdown of proline or glutamine/glutamate * from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperammonemia
Hyperammonemia is a metabolic disturbance characterised by an excess of ammonia in the blood. It is a dangerous condition that may lead to brain injury and death. It may be primary or secondary. Ammonia is a substance that contains nitrogen. It is a product of the catabolism of protein. It is converted to the less toxic substance urea prior to excretion in urine by the kidneys. The metabolic pathways that synthesize urea involve reactions that start in the mitochondria and then move into the cytosol. The process is known as the urea cycle, which comprises several enzymes acting in sequence. It is greatly exacerbated by common zinc deficiency, which raises ammonia levels further. Signs and symptoms Complication Hyperammonemia is one of the metabolic derangements that contribute to hepatic encephalopathy, which can cause swelling of astrocytes and stimulation of NMDA receptors in the brain. Overstimulation of NMDA receptors induces excitotoxicity. Diagnosis Types Primary vs. s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleotide
Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all life-forms on Earth. Nucleotides are obtained in the diet and are also synthesized from common nutrients by the liver. Nucleotides are composed of three subunit molecules: a nucleobase, a five-carbon sugar ( ribose or deoxyribose), and a phosphate group consisting of one to three phosphates. The four nucleobases in DNA are guanine, adenine, cytosine and thymine; in RNA, uracil is used in place of thymine. Nucleotides also play a central role in metabolism at a fundamental, cellular level. They provide chemical energy—in the form of the nucleoside triphosphates, adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP) and uridine triphosphate (UTP)—throughout the cell for the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondria
A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. They were discovered by Albert von Kölliker in 1857 in the voluntary muscles of insects. The term ''mitochondrion'' was coined by Carl Benda in 1898. The mitochondrion is popularly nicknamed the "powerhouse of the cell", a phrase coined by Philip Siekevitz in a 1957 article of the same name. Some cells in some multicellular organisms lack mitochondria (for example, mature mammalian red blood cells). A large number of unicellular organisms, such as microsporidia, parabasalids and diplomonads, have reduced or transformed their mitochondria into other structures. One eukaryote, ''Monocercomonoides'', is known to have completely lost its mitochondria, and one multicellular organism, ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citrin
Citrin, also known as solute carrier family 25, member 13 (citrin) or SLC25A13, is a protein which in humans is encoded by the ''SLC25A13'' gene. Citrin is associated with type II citrullinemia Citrullinemia is an autosomal recessive urea cycle disorder that causes ammonia and other toxic substances to accumulate in the blood.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. . Two for ... and neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). See also * Solute carrier family References External links * GeneReviews/NCBI/NIH/UW entry on Citrin Deficiency* * Solute carrier family EF-hand-containing proteins {{membrane-protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Eastern
The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabia (including the Arabian Peninsula and Bahrain), Asia Minor (Asian part of Turkey except Hatay Province), East Thrace (European part of Turkey), Egypt, Iran, the Levant (including Ash-Shām and Cyprus), Mesopotamia (modern-day Iraq), and the Socotra Archipelago (a part of Yemen). The term came into widespread usage as a replacement of the term Near East (as opposed to the Far East) beginning in the early 20th century. The term "Middle East" has led to some confusion over its changing definitions, and has been viewed by some to be discriminatory or too Eurocentric. The region includes the vast majority of the territories included in the closely associated definition of Western Asia (including Iran), but without the South Caucasus, and additionally includes all of Egypt (not just the Sinai Region) and all of Turkey (not just the part barring East Thrace). Most M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Asia
East Asia is the eastern region of Asia, which is defined in both Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea and Taiwan are all unrecognised by at least one other East Asian state due to severe ongoing War, political tensions in the region, specifically the division of Korea and the political status of Taiwan. Hong Kong and Macau, two small coastal Dependent territory, quasi-dependent territories located in the south of China, are officially highly autonomous but are under Chinese sovereignty. Economy of Japan, Japan, Economy of Taiwan, Taiwan, Economy of South Korea, South Korea, Economy of China, Mainland China, Economy of Hong Kong, Hong Kong, and Economy of Macau, Macau are among the world's largest and most prosperous economies. East Asia borders Siberia and the Russian Far East to the north, Southeast Asia to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north toward the East China Sea, Philippine Sea, and Taiwan in the south. Japan is a part of the Ring of Fire, and spans Japanese archipelago, an archipelago of List of islands of Japan, 6852 islands covering ; the five main islands are Hokkaido, Honshu (the "mainland"), Shikoku, Kyushu, and Okinawa Island, Okinawa. Tokyo is the Capital of Japan, nation's capital and largest city, followed by Yokohama, Osaka, Nagoya, Sapporo, Fukuoka, Kobe, and Kyoto. Japan is the List of countries and dependencies by population, eleventh most populous country in the world, as well as one of the List of countries and dependencies by population density, most densely populated and Urbanization by country, urbanized. About three-fourths of Geography of Japan, the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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