Biological Pathway: Reactome:R-HSA-2243919
Crosslinking of collagen fibrils related metabolites
find 11 related metabolites which is associated with the biological pathway Crosslinking of collagen fibrils
this pathway object is a organism specific pathway, which is related to taxonomy Homo sapiens (human).
After removal of the N- and C-procollagen propeptides, fibrillar collagen molecules aggregate into microfibrillar arrays, stabilized by covalent intermolecular cross-links. These depend on the oxidative deamination of specific lysine or hydroxylysine residues in the telopeptide region by lysyl oxidase (LOX) with the subsequent spontaneous formation of covalent intermolecular cross-links (Pinnell & Martin 1968, Siegel et al. 1970, 1974, Maki 2009, Nishioka et al. 2012). Hydroxylysine is formed intracellularly by lysine hydroxylases (LH). There are different forms of LH responsible for hydroxylation of helical and telopeptide lysines (Royce & Barnes 1985, Knott et al.1997, Takaluoma et al. 2007, Myllyla 2007). The chemistry of the cross-links formed depends on whether lysines or hydroxylysines are present in the telopeptides (Barnes et al. 1974), which depends on the proportion of collagen lysines post-translationally converted to hydroxylysine by LH. The lysine pathway predominates in adult skin, cornea and sclera while the hydroxylysine pathway occurs primarily in bone, cartilage, ligament, tendons, embryonic skin and most connective tissues (Eyre 1987, Eyre & Wu 2005, Eyre et al. 2008). Oxidative deamination of lysine or hydroxylysine residues by LOX generates the allysine and hydroxyallysine aldehydes respectively. These can spontaneously react with either another aldehyde to form an aldol condensation product (intramolecular cross-link), or with an unmodified lysine or hydroxylysine residue to form intermolecular cross-links.
The pathway of cross-linking is regulated primarily by the hydroxylation pattern of telopeptide and triple-helix domain lysine residues. When lysine residues are the source of aldehydes formed by lysyl oxidase the allysine cross-linking pathway leads to the formation of aldimine cross-links (Eyre & Wu 2005). These are stable at physiological conditions but readily cleaved at acid pH or elevated temperature. When hydroxylysine residues are the source of aldehydes formed by lysyl oxidase the hydroxyallysine cross-linking pathway leads to the formation of more stable ketoimine cross-links.
Telopeptide lysine residues can be converted by LOX to allysine, which can react with a helical hydroxylysine residue forming the lysine aldehyde aldimine cross-link dehydro hydroxylysino norleucine (deHHLNL) (Bailey & Peach 1968, Eyre et al. 2008). If the telopeptide residue is hydroxylysine, the hydroxyallysine formed by LOX can react with a helical hydroxylysine forming the Schiff base, which spontaneously undergoes an Amadori rearrangement resulting in the ketoimine cross link hydroxylysino 5 ketonorleucine (HLKNL). This stable cross-link is formed in tissues where telopeptide residues are predominanly hydroxylated, such as foetal bone and cartilage, accounting for the relative insolubility of collagen from these tissues (Bailey et al. 1998). In bone, telopeptide hydroxyallysines can react with the epsilon-amino group of a helical lysine (Robins & Bailey 1975). The resulting Schiff base undergoes Amadori rearrangement to form lysino-hydroxynorleucine (LHNL). An alternative mechanism of maturation of ketoimine cross-links has been reported in cartilage leading to the formation of arginoline (Eyre et al. 2010).
These divalent crosslinks greatly diminish as connective tissues mature, due to further spontaneous reactions (Bailey & Shimokomaki 1971, Robins & Bailey 1973) with neighbouring peptides that result in tri- and tetrafunctional cross-links. In mature tissues collagen cross-links are predominantly trivalent. The most common are pyridinoline or 3-hydroxypyridinium cross-links, namely hydroxylysyl-pyridinoline (HL-Pyr) and lysyl-pyridinoline (L-Pyr) cross-links (Eyre 1987, Ogawa et al. 1982, Fujimoto et al. 1978). HL-Pyr is formed from three hydroxylysine residues, HLKNL plus a further hydroxyallysine. It predominates in highly hydroxylated collagens such as type II collagen in cartilage. L-Pyr is formed from two hydroxylysines and a lysine, LKNL plus a further hydroxyallysine, found mostly in calcified tissues (Bailey et al. 1998). Trivalent collagen cross-links can also form as pyrroles, either Lysyl-Pyrrole (L-Pyrrole) or hydroxylysyl-pyrrole (HL-Pyrrole), respectively formed when LKNL or HLKNL react with allysine (Scott et al. 1981, Kuypers et al. 1992). A further three-way crosslink can form when DeH-HLNL reacts with histidine to form histidino-hydroxylysinonorleucine (HHL), found in skin and cornea (Yamauchi et al. 1987, 1996). This can react with an additional lysine to form the tetrafunctional cross-link histidinohydroxymerodesmosine (Reiser et al. 1992, Yamauchi et al. 1996).
Another mechanism which could be involved in the cross-linking of collagen IV networks is the sulfilimine bond (Vanacore et al. 2009), catalyzed by peroxidasin, an enzyme found in basement membrane (Bhave 2012).
To improve clarity inter-chain cross-linking is represented here for Collagen type I only. Although the formation of each type of cross-link is represented here as an independent event, the partial and random nature of lysine hydroxylation and subsequent lysyl oxidation means that any combination of these cross-linking events could occur within the same collagen fibril .
Water
Water is a chemical substance that is essential to all known forms of life. It appears colorless to the naked eye in small quantities, though it is actually slightly blue in color. It covers 71\\% of Earths surface. Current estimates suggest that there are 1.4 billion cubic kilometers (330 million m3) of it available on Earth, and it exists in many forms. It appears mostly in the oceans (saltwater) and polar ice caps, but it is also present as clouds, rain water, rivers, freshwater aquifers, lakes, and sea ice. Water in these bodies perpetually moves through a cycle of evaporation, precipitation, and runoff to the sea. Clean water is essential to human life. In many parts of the world, it is in short supply. From a biological standpoint, water has many distinct properties that are critical for the proliferation of life that set it apart from other substances. It carries out this role by allowing organic compounds to react in ways that ultimately allow replication. All known forms of life depend on water. Water is vital both as a solvent in which many of the bodys solutes dissolve and as an essential part of many metabolic processes within the body. Metabolism is the sum total of anabolism and catabolism. In anabolism, water is removed from molecules (through energy requiring enzymatic chemical reactions) in order to grow larger molecules (e.g. starches, triglycerides and proteins for storage of fuels and information). In catabolism, water is used to break bonds in order to generate smaller molecules (e.g. glucose, fatty acids and amino acids to be used for fuels for energy use or other purposes). Water is thus essential and central to these metabolic processes. Water is also central to photosynthesis and respiration. Photosynthetic cells use the suns energy to split off waters hydrogen from oxygen. Hydrogen is combined with CO2 (absorbed from air or water) to form glucose and release oxygen. All living cells use such fuels and oxidize the hydrogen and carbon to capture the suns energy and reform water and CO2 in the process (cellular respiration). Water is also central to acid-base neutrality and enzyme function. An acid, a hydrogen ion (H+, that is, a proton) donor, can be neutralized by a base, a proton acceptor such as hydroxide ion (OH-) to form water. Water is considered to be neutral, with a pH (the negative log of the hydrogen ion concentration) of 7. Acids have pH values less than 7 while bases have values greater than 7. Stomach acid (HCl) is useful to digestion. However, its corrosive effect on the esophagus during reflux can temporarily be neutralized by ingestion of a base such as aluminum hydroxide to produce the neutral molecules water and the salt aluminum chloride. Human biochemistry that involves enzymes usually performs optimally around a biologically neutral pH of 7.4. (Wikipedia). Water, also known as purified water or dihydrogen oxide, is a member of the class of compounds known as homogeneous other non-metal compounds. Homogeneous other non-metal compounds are inorganic non-metallic compounds in which the largest atom belongs to the class of other nonmetals. Water can be found in a number of food items such as caraway, oxheart cabbage, alaska wild rhubarb, and japanese walnut, which makes water a potential biomarker for the consumption of these food products. Water can be found primarily in most biofluids, including ascites Fluid, blood, cerebrospinal fluid (CSF), and lymph, as well as throughout all human tissues. Water exists in all living species, ranging from bacteria to humans. In humans, water is involved in several metabolic pathways, some of which include cardiolipin biosynthesis CL(20:4(5Z,8Z,11Z,14Z)/18:0/20:4(5Z,8Z,11Z,14Z)/18:2(9Z,12Z)), cardiolipin biosynthesis cl(i-13:0/i-15:0/i-20:0/i-24:0), cardiolipin biosynthesis CL(18:0/18:0/20:4(5Z,8Z,11Z,14Z)/22:5(7Z,10Z,13Z,16Z,19Z)), and cardiolipin biosynthesis cl(a-13:0/i-18:0/i-13:0/i-19:0). Water is also involved in several metabolic disorders, some of which include de novo triacylglycerol biosynthesis tg(i-21:0/i-13:0/21:0), de novo triacylglycerol biosynthesis tg(22:0/20:0/i-20:0), de novo triacylglycerol biosynthesis tg(a-21:0/i-20:0/i-14:0), and de novo triacylglycerol biosynthesis tg(i-21:0/a-17:0/i-12:0). Water is a drug which is used for diluting or dissolving drugs for intravenous, intramuscular or subcutaneous injection, according to instructions of the manufacturer of the drug to be administered [fda label]. Water plays an important role in the world economy. Approximately 70\\% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of long-distance trade of commodities (such as oil and natural gas) and manufactured products is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a wide variety of chemical substances; as such it is widely used in industrial processes, and in cooking and washing. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, and diving .
Oxygen
Oxygen is the third most abundant element in the universe after hydrogen and helium and the most abundant element by mass in the Earths crust. Diatomic oxygen gas constitutes 20.9\\% of the volume of air. All major classes of structural molecules in living organisms, such as proteins, carbohydrates, and fats, contain oxygen, as do the major inorganic compounds that comprise animal shells, teeth, and bone. Oxygen in the form of O2 is produced from water by cyanobacteria, algae and plants during photosynthesis and is used in cellular respiration for all living organisms. Green algae and cyanobacteria in marine environments provide about 70\\% of the free oxygen produced on earth and the rest is produced by terrestrial plants. Oxygen is used in mitochondria to help generate adenosine triphosphate (ATP) during oxidative phosphorylation. For animals, a constant supply of oxygen is indispensable for cardiac viability and function. To meet this demand, an adult human, at rest, inhales 1.8 to 2.4 grams of oxygen per minute. This amounts to more than 6 billion tonnes of oxygen inhaled by humanity per year. At a resting pulse rate, the heart consumes approximately 8-15 ml O2/min/100 g tissue. This is significantly more than that consumed by the brain (approximately 3 ml O2/min/100 g tissue) and can increase to more than 70 ml O2/min/100 g myocardial tissue during vigorous exercise. As a general rule, mammalian heart muscle cannot produce enough energy under anaerobic conditions to maintain essential cellular processes; thus, a constant supply of oxygen is indispensable to sustain cardiac function and viability. However, the role of oxygen and oxygen-associated processes in living systems is complex, and they and can be either beneficial or contribute to cardiac dysfunction and death (through reactive oxygen species). Reactive oxygen species (ROS) are a family of oxygen-derived free radicals that are produced in mammalian cells under normal and pathologic conditions. Many ROS, such as the superoxide anion (O2-)and hydrogen peroxide (H2O2), act within blood vessels, altering mechanisms mediating mechanical signal transduction and autoregulation of cerebral blood flow. Reactive oxygen species are believed to be involved in cellular signaling in blood vessels in both normal and pathologic states. The major pathway for the production of ROS is by way of the one-electron reduction of molecular oxygen to form an oxygen radical, the superoxide anion (O2-). Within the vasculature there are several enzymatic sources of O2-, including xanthine oxidase, the mitochondrial electron transport chain, and nitric oxide (NO) synthases. Studies in recent years, however, suggest that the major contributor to O2- levels in vascular cells is the membrane-bound enzyme NADPH-oxidase. Produced O2- can react with other radicals, such as NO, or spontaneously dismutate to produce hydrogen peroxide (H2O2). In cells, the latter reaction is an important pathway for normal O2- breakdown and is usually catalyzed by the enzyme superoxide dismutase (SOD). Once formed, H2O2 can undergo various reactions, both enzymatic and nonenzymatic. The antioxidant enzymes catalase and glutathione peroxidase act to limit ROS accumulation within cells by breaking down H2O2 to H2O. Metabolism of H2O2 can also produce other, more damaging ROS. For example, the endogenous enzyme myeloperoxidase uses H2O2 as a substrate to form the highly reactive compound hypochlorous acid. Alternatively, H2O2 can undergo Fenton or Haber-Weiss chemistry, reacting with Fe2+/Fe3+ ions to form toxic hydroxyl radicals (-.OH). (PMID: 17027622, 15765131) [HMDB]. Oxygen is found in many foods, some of which are soy bean, watermelon, sweet basil, and spinach. Oxygen is the third most abundant element in the universe after hydrogen and helium and the most abundant element by mass in the Earths crust. Diatomic oxygen gas constitutes 20.9\\% of the volume of air. All major classes of structural molecules in living organisms, such as proteins, carbohydrates, and fats, contain oxygen, as do the major inorganic compounds that comprise animal shells, teeth, and bone. Oxygen in the form of O2 is produced from water by cyanobacteria, algae and plants during photosynthesis and is used in cellular respiration for all living organisms. Green algae and cyanobacteria in marine environments provide about 70\\% of the free oxygen produced on earth and the rest is produced by terrestrial plants. Oxygen is used in mitochondria to help generate adenosine triphosphate (ATP) during oxidative phosphorylation. For animals, a constant supply of oxygen is indispensable for cardiac viability and function. To meet this demand, an adult human, at rest, inhales 1.8 to 2.4 grams of oxygen per minute. This amounts to more than 6 billion tonnes of oxygen inhaled by humanity per year. At a resting pulse rate, the heart consumes approximately 8-15 ml O2/min/100 g tissue. This is significantly more than that consumed by the brain (approximately 3 ml O2/min/100 g tissue) and can increase to more than 70 ml O2/min/100 g myocardial tissue during vigorous exercise. As a general rule, mammalian heart muscle cannot produce enough energy under anaerobic conditions to maintain essential cellular processes; thus, a constant supply of oxygen is indispensable to sustain cardiac function and viability. However, the role of oxygen and oxygen-associated processes in living systems is complex, and they and can be either beneficial or contribute to cardiac dysfunction and death (through reactive oxygen species). Reactive oxygen species (ROS) are a family of oxygen-derived free radicals that are produced in mammalian cells under normal and pathologic conditions. Many ROS, such as the superoxide anion (O2-)and hydrogen peroxide (H2O2), act within blood vessels, altering mechanisms mediating mechanical signal transduction and autoregulation of cerebral blood flow. Reactive oxygen species are believed to be involved in cellular signaling in blood vessels in both normal and pathologic states. The major pathway for the production of ROS is by way of the one-electron reduction of molecular oxygen to form an oxygen radical, the superoxide anion (O2-). Within the vasculature there are several enzymatic sources of O2-, including xanthine oxidase, the mitochondrial electron transport chain, and nitric oxide (NO) synthases. Studies in recent years, however, suggest that the major contributor to O2- levels in vascular cells is the membrane-bound enzyme NADPH-oxidase. Produced O2- can react with other radicals, such as NO, or spontaneously dismutate to produce hydrogen peroxide (H2O2). In cells, the latter reaction is an important pathway for normal O2- breakdown and is usually catalyzed by the enzyme superoxide dismutase (SOD). Once formed, H2O2 can undergo various reactions, both enzymatic and nonenzymatic. The antioxidant enzymes catalase and glutathione peroxidase act to limit ROS accumulation within cells by breaking down H2O2 to H2O. Metabolism of H2O2 can also produce other, more damaging ROS. For example, the endogenous enzyme myeloperoxidase uses H2O2 as a substrate to form the highly reactive compound hypochlorous acid. Alternatively, H2O2 can undergo Fenton or Haber-Weiss chemistry, reacting with Fe2+/Fe3+ ions to form toxic hydroxyl radicals (-.OH). (PMID: 17027622, 15765131). V - Various > V03 - All other therapeutic products > V03A - All other therapeutic products > V03AN - Medical gases
ammonia
An azane that consists of a single nitrogen atom covelently bonded to three hydrogen atoms. Ammonia, also known as nh3 or ammonia solution, is a member of the class of compounds known as homogeneous other non-metal compounds. Homogeneous other non-metal compounds are inorganic non-metallic compounds in which the largest atom belongs to the class of other nonmetals. Ammonia can be found in a number of food items such as rose hip, yardlong bean, cereals and cereal products, and ceylon cinnamon, which makes ammonia a potential biomarker for the consumption of these food products. Ammonia can be found primarily in blood, cellular cytoplasm, cerebrospinal fluid (CSF), and urine, as well as throughout all human tissues. Ammonia exists in all eukaryotes, ranging from yeast to humans. In humans, ammonia is involved in several metabolic pathways, some of which include glucose-alanine cycle, phenylalanine and tyrosine metabolism, homocysteine degradation, and d-arginine and d-ornithine metabolism. Ammonia is also involved in several metabolic disorders, some of which include ureidopropionase deficiency, hyperornithinemia-hyperammonemia-homocitrullinuria [hhh-syndrome], non ketotic hyperglycinemia, and beta-mercaptolactate-cysteine disulfiduria. Moreover, ammonia is found to be associated with 3-Hydroxy-3-methylglutaryl-CoA lyase deficiency, 3-Methyl-crotonyl-glycinuria, citrullinemia type I, and short bowel syndrome. Ammonia is a non-carcinogenic (not listed by IARC) potentially toxic compound. Ammonia or azane is a compound of nitrogen and hydrogen with the formula NH3. The simplest pnictogen hydride, ammonia is a colourless gas with a characteristic pungent smell. It is a common nitrogenous waste, particularly among aquatic organisms, and it contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceutical products and is used in many commercial cleaning products . Acute Exposure: EYES: irrigate opened eyes for several minutes under running water. INGESTION: do not induce vomiting. Rinse mouth with water (never give anything by mouth to an unconscious person). Seek immediate medical advice. SKIN: should be treated immediately by rinsing the affected parts in cold running water for at least 15 minutes, followed by thorough washing with soap and water. If necessary, the person should shower and change contaminated clothing and shoes, and then must seek medical attention. INHALATION: supply fresh air. If required provide artificial respiration. (z)-n-coumaroyl-5-hydroxyanthranilic acid is a member of the class of compounds known as avenanthramides. Avenanthramides are a group of phenolic alkaloids consisting of conjugate of three phenylpropanoids (ferulic, caffeic, or p-coumaric acid) and anthranilic acid (z)-n-coumaroyl-5-hydroxyanthranilic acid is practically insoluble (in water) and a weakly acidic compound (based on its pKa). (z)-n-coumaroyl-5-hydroxyanthranilic acid can be found in cereals and cereal products and oat, which makes (z)-n-coumaroyl-5-hydroxyanthranilic acid a potential biomarker for the consumption of these food products.
Hydrogen peroxide
Hydrogen peroxide (H2O2) is a very pale blue liquid that appears colourless in a dilute solution. H2O2 is slightly more viscous than water and is a weak acid. H2O2 is unstable and slowly decomposes in the presence of light. It has strong oxidizing properties and is, therefore, a powerful bleaching agent that is mostly used for bleaching paper. H2O2 has also found use as a disinfectant and as an oxidizer. H2O2 in the form of carbamide peroxide is widely used for tooth whitening (bleaching), both in professionally- and in self-administered products. H2O2 is a well-documented component of living cells and is a normal metabolite of oxygen in the aerobic metabolism of cells and tissues. A total of 31 human cellular H2O2 generating enzymes has been identified so far (PMID: 25843657). H2O2 plays important roles in host defence and oxidative biosynthetic reactions. At high levels (>100 nM) H2O2 is toxic to most cells due to its ability to non-specifically oxidize proteins, membranes and DNA, leading to general cellular damage and dysfunction. However, at low levels (<10 nM), H2O2 functions as a signalling agent, particularly in higher organisms. In plants, H2O2 plays a role in signalling to cause cell shape changes such as stomatal closure and root growth. As a messenger molecule in vertebrates, H2O2 diffuses through cells and tissues to initiate cell shape changes, to drive vascular remodelling, and to activate cell proliferation and recruitment of immune cells. H2O2 also plays a role in redox sensing, signalling, and redox regulation (PMID: 28110218). This is normally done through molecular redox “switches” such as thiol-containing proteins. The production and decomposition of H2O2 are tightly regulated (PMID: 17434122). In humans, H2O2 can be generated in response to various stimuli, including cytokines and growth factors. H2O2 is degraded by several enzymes including catalase and superoxide dismutase (SOD), both of which play important roles in keeping the amount of H2O2 in the body below toxic levels. H2O2 also appears to play a role in vitiligo. Vitiligo is a skin pigment disorder leading to patchy skin colour, especially among dark-skinned individuals. Patients with vitiligo have low catalase levels in their skin, leading to higher levels of H2O2. High levels of H2O2 damage the epidermal melanocytes, leading to a loss of pigment (PMID: 10393521). Accumulating evidence suggests that hydrogen peroxide H2O2 plays an important role in cancer development. Experimental data have shown that cancer cells produce high amounts of H2O2. An increase in the cellular levels of H2O2 has been linked to several key alterations in cancer, including DNA changes, cell proliferation, apoptosis resistance, metastasis, angiogenesis and hypoxia-inducible factor 1 (HIF-1) activation (PMID: 17150302, 17335854, 16677071, 16607324, 16514169). H2O2 is found in most cells, tissues, and biofluids. H2O2 levels in the urine can be significantly increased with the consumption of coffee and other polyphenolic-containing beverages (wine, tea) (PMID: 12419961). In particular, roasted coffee has high levels of 1,2,4-benzenetriol which can, on its own, lead to the production of H2O2. Normal levels of urinary H2O2 in non-coffee drinkers or fasted subjects are between 0.5-3 uM/mM creatinine whereas, for those who drink coffee, the levels are between 3-10 uM/mM creatinine (PMID: 12419961). It is thought that H2O2 in urine could act as an antibacterial agent and that H2O2 is involved in the regulation of glomerular function (PMID: 10766414). A - Alimentary tract and metabolism > A01 - Stomatological preparations > A01A - Stomatological preparations > A01AB - Antiinfectives and antiseptics for local oral treatment D - Dermatologicals > D08 - Antiseptics and disinfectants > D08A - Antiseptics and disinfectants S - Sensory organs > S02 - Otologicals > S02A - Antiinfectives > S02AA - Antiinfectives It is used in foods as a bleaching agent, antimicrobial agent and oxidising agent C254 - Anti-Infective Agent > C28394 - Topical Anti-Infective Agent D009676 - Noxae > D016877 - Oxidants > D010545 - Peroxides D000890 - Anti-Infective Agents
Bromide
Bromine is a brown or red liquid with a characteristic odor. Bromine is mainly used in the manufacture of dyes, inks, flame retardants, pharmaceuticals and chemical warfare agents. Occupational exposure to bromine may occur during the production and the application of bromine compounds and during other industrial activities. This compound is adsorbed into the human body through the respiratory tract, skin (occupational exposure) and alimentary tract (general population). Physiologically, bromine exists as an ion in the body. Slight eye irritation occurs as a consequence of chronic exposure to bromine vapors at concentration of 1 mg/m3. Higher concentrations increase this effect and cause nasal and skin irritation. Many years observations have shown that during occupational exposure to bromine vapors at concentrations of up to 0.7 mg/m3 (0.1 ppm), there are no observed adverse effects. From cytotoxicity and mutagenicity assays, it is known that brominated organic compounds are more toxic than chlorinated organic compounds. However, only a limited number of brominated organic compounds have been regulated. (PMID: 17316744). Bromine is a brown or red liquid with a characteristic odor. Bromine is mainly used in the manufacture of dyes, inks, flame retardants, pharmaceuticals and chemical warfare agents. Occupational exposure to bromine may occur during the production and the application of bromine compounds and during other industrial activities. This compound is adsorbed into the human body through the respiratory tract, skin (occupational exposure) and alimentary tract (general population). Physiologically, bromine exists as an ion in the body. Slight eye irritation occurs as a consequence of chronic exposure to bromine vapors at concentration of 1 mg/m3. Higher concentrations increase this effect and cause nasal and skin irritation. Many years observations have shown that during occupational exposure to bromine vapors at concentrations of up to 0.7 mg/m3 (0.1 ppm), there are no observed adverse effects. D002491 - Central Nervous System Agents > D000927 - Anticonvulsants > D001965 - Bromides N - Nervous system > N05 - Psycholeptics > N05C - Hypnotics and sedatives
Ammonia
Ammonia is a colourless alkaline gas and is one of the most abundant nitrogen-containing compounds in the atmosphere. It is an irritant with a characteristic pungent odor that is widely used in industry. Inasmuch as ammonia is highly soluble in water and, upon inhalation, is deposited in the upper airways, occupational exposures to ammonia have commonly been associated with sinusitis, upper airway irritation, and eye irritation. Acute exposures to high levels of ammonia have also been associated with diseases of the lower airways and interstitial lung. Small amounts of ammonia are naturally formed in nearly all tissues and organs of the vertebrate organism. Ammonia is both a neurotoxin and a metabotoxin. In fact, it is the most common endogenous neurotoxin. A neurotoxin is a compound that causes damage to neural tissue and neural cells. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Ammonia is recognized to be central in the pathogenesis of a brain condition known as hepatic encephalopathy, which arises from various liver diseases and leads to a build up ammonia in the blood (hyperammonemia). More than 40\\% of people with cirrhosis develop hepatic encephalopathy. Part of the neurotoxicity of ammonia arises from the fact that it easily crosses the blood-brain barrier and is absorbed and metabolized by the astrocytes, a population of cells in the brain that constitutes 30\\% of the cerebral cortex. Astrocytes use ammonia when synthesizing glutamine from glutamate. The increased levels of glutamine lead to an increase in osmotic pressure in the astrocytes, which become swollen. There is increased activity of the inhibitory gamma-aminobutyric acid (GABA) system, and the energy supply to other brain cells is decreased. This can be thought of as an example of brain edema. The source of the ammonia leading to hepatic encaphlopahy is not entirely clear. The gut produces ammonia, which is metabolized in the liver, and almost all organ systems are involved in ammonia metabolism. Colonic bacteria produce ammonia by splitting urea and other amino acids, however this does not fully explain hyperammonemia and hepatic encephalopathy. The alternative explanation is that hyperammonemia is the result of intestinal breakdown of amino acids, especially glutamine. The intestines have significant glutaminase activity, predominantly located in the enterocytes. On the other hand, intestinal tissues only have a little glutamine synthetase activity, making it a major glutamine-consuming organ. In addition to the intestine, the kidney is an important source of blood ammonia in patients with liver disease. Ammonia is also taken up by the muscle and brain in hepatic coma, and there is confirmation that ammonia is metabolized in muscle. Excessive formation of ammonia in the brains of Alzheimers disease patients has also been demonstrated, and it has been shown that some Alzheimers disease patients exhibit elevated blood ammonia concentrations. Ammonia is the most important natural modulator of lysosomal protein processing. Indeed, there is strong evidence for the involvement of aberrant lysosomal processing of beta-amyloid precursor protein (beta-APP) in the formation of amyloid deposits. Inflammatory processes and activation of microglia are widely believed to be implicated in the pathology of Alzheimers disease. Ammonia is able to affect the characteristic functions of microglia, such as endocytosis, and cytokine production. Based on these facts, an ammonia-based hypothesis for Alzheimers disease has been suggested (PMID: 17006913, 16167195, 15377862, 15369278). Chronically high levels of ammonia in the blood are associated with nearly twenty different inborn errors of metabolism including: 3-hydroxy-3-methylglutaryl-CoA lyase deficiency, 3-methyl-crotonylglycinuria, argininemia, argininosuccinic aciduria, beta-ketothiolase deficiency, biotinidase deficiency, carbamoyl phosphate synthetase... Ammonia is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or indirectly, is also a building block for the synthesis of many pharmaceuticals. Although in wide use, ammonia is both caustic and hazardous. Ammonia is found in many foods, some of which are spinach, common beet, ucuhuba, and oriental wheat.
H2O
An oxygen hydride consisting of an oxygen atom that is covalently bonded to two hydrogen atoms. Water. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=7732-18-5 (retrieved 2024-10-17) (CAS RN: 7732-18-5). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).
hydrogen peroxide
A - Alimentary tract and metabolism > A01 - Stomatological preparations > A01A - Stomatological preparations > A01AB - Antiinfectives and antiseptics for local oral treatment An inorganic peroxide consisting of two hydroxy groups joined by a covalent oxygen-oxygen single bond. D - Dermatologicals > D08 - Antiseptics and disinfectants > D08A - Antiseptics and disinfectants S - Sensory organs > S02 - Otologicals > S02A - Antiinfectives > S02AA - Antiinfectives C254 - Anti-Infective Agent > C28394 - Topical Anti-Infective Agent D009676 - Noxae > D016877 - Oxidants > D010545 - Peroxides D000890 - Anti-Infective Agents
