Browsing Pathways

Alimemazine (trimeprazine) is a first-generation phenothiazine H1-antihistamine. H1-antihistamines interfere with the agonist action of histamine at the H1 receptor and are administered to attenuate inflammatory process in order to treat conditions such as allergic rhinitis, allergic conjunctivitis, and urticaria. Reducing the activity of the NF-κB immune response transcription factor through the phospholipase C and the phosphatidylinositol (PIP2) signalling pathways also decreases antigen presentation and the expression of pro-inflammatory cytokines, cell adhesion molecules, and chemotactic factors. Furthermore, lowering calcium ion concentration leads to increased mast cell stability which reduces further histamine release. First-generation antihistamines readily cross the blood-brain barrier and cause sedation and other adverse central nervous system (CNS) effects (e.g. nervousness and insomnia). Second-generation antihistamines are more selective for H1-receptors of the peripheral nervous system (PNS) and do not cross the blood-brain barrier. Consequently, these newer drugs elicit fewer adverse drug reactions.

Hyperornithinemia with gyrate atrophy (HOGA), also known as gyrate atrophy of the choroid and retina, OAT deficiency, ornithine aminotransferase deficiency, ornithine keto acid aminotransferase deficiency) is an autosomal recessive disorder of ornithine metabolism caused by a defective ornithine aminotransferase (OAT). OAT catalyzes the conversion of ornithine into proline which is a conditionally essential amino acid. This disease is characterized by a very large accumulation of ornithine in the blood, urine, spinal fluid, and aqueous humour. Symptoms of the disease include early cataract formation, progressive chorioretinal degeneration, and type II muscle fiber atrophy. Some cases of HOGA are vitamin B6-responsive.

Prolinemia Type II is caused by mutation in the pyrroline-5-carboxylate dehydrogenase gene (P5CDH) mitochondrial matrix NAD-dependent dehydrogenase. This dehydrogenase is a catalyst for converting pyrroline-5-carboxylate to glutamate in the proline degradation pathway. An enzyme defect causes accumulation of glycine, hydroxyproline and proline in the urine, ornithine in the serum and proline in plasma. Symptoms include mental retardation, acute and chronic renal failure, and seizures.

Methylcobalamin (MeCbl) is the cofactor of methionine synthase and involved in the conversion of homocysteine to methionine. Adenosylcobalamin (AdoCbl) is a cofactor for methylmalonyl CoA mutase converting methylmalonic acid into succinic acid. Methylmalonyl-CoA mutase is involved in key metabolic pathways, catalyzing the isomerization of methylmalonyl-CoA to succinyl-CoA. It requires its Vitamin B12 derived prosthetic group, adenosylcobalamin, to function.It catalyzes the isomerization of methylmalonyl-CoA to succinyl-CoA. It requires its Vitamin B12 derived prosthetic group, adenosylcobalamin, to function. Defects in these cofactors for methylmalonyl CoA mutase cause accumulation of ammonia in blood; methylmalonic acid in plasma; creatinine and uric acid in serum; 3-Aminoisobutyric acid, 3-Hydroxypropionic acid, 3-Hydroxyvaleric acid, glycine, methylcitric acid and methylmalonic acid in urine; and methylmalonic acid in spinal fluid. Symptoms include anemia, dehydration, growth retardation, nephrosis, respiratory distress and metabolic acidosis.

Infantile hypophosphatasia, also called I-HPP, is a severe, rare and fatal metabolic bone disease and an inborn error of metabolism. I-HPP is caused by a defective alkaline phosphatase, tissue-nonspecific isozyme, which catalyzes the conversion of pyridoxal 5'-phosphate into pyridoxal and conversion of pyridoxamine 5'-phosphate to pyridoxamine. Both products are important for later metabolism. Early symptoms of the disorder include poor feeding, irritability, hypotonia (state of low muscle tone), failure to thrive and seizures.. Treatment with enzyme replacement therapy using bone-targeting recombinant alkaline phosphatase is very effective. It is a very rare genetic disease happened in infant, with 90 cases have been reported to date.

Vitamin A deficiency can be caused by many causes. A defect in the BCMO1 gene which codes for beta,beta-carotene 15,15’-monooxygenase is one of them. Beta,beta-carotene 15,15’-monooxygenase catalyzes the chemical reaction where the two substrates are beta-carotene and O2, whereas its product is retinal. A defect in this enzyme results in decrease of levels of retinal and vitamin A in serum; Signs and symptoms include night blindness, poor adaptation to darkness, dry skin and hair.

Antipyrine (also named Fenazone or Phenazone) is often used for testing the effect of other drugs on drug-metabolizing enzymes in the liver. Antipyrine can block prostaglandin synthesis by the action of inhibition of prostaglandin G/H synthase 1 and 2. Prostaglandin G/H synthase 1 and 2 catalyze the arachidonic acid to prostaglandin G2, and also catalyze prostaglandin G2 to prostaglandin H2 in the metabolism pathway. Decreased prostaglandin synthesis in many animal model's cell is caused by presence of antipyrine.

Indomethacin (also named Amuno or Indocid) is a nonsteroidal anti-inflammatory drug (NSAID). It can be used to treat prostaglandin G/H synthase related fever, swelling, pain and inflammation. Indomethacin can block prostaglandin synthesis by the action of inhibition of prostaglandin G/H synthase 1 and 2. Prostaglandin G/H synthase 1 and 2 catalyze the arachidonic acid to prostaglandin G2, and also catalyze prostaglandin G2 to prostaglandin H2 in the metabolism pathway. Decreased prostaglandin synthesis is caused by presence of indomethacin.

Carprofen (also named Rimadyl or Imadyl) is a nonsteroidal anti-inflammatory drug that can treat various joint pain or post-operative pain. Carprofen can block prostaglandin synthesis by the action of inhibition of prostaglandin G/H synthase 1 and 2. Prostaglandin G/H synthase 1 and 2 catalyze the arachidonic acid to prostaglandin G2, and also catalyze prostaglandin G2 to prostaglandin H2 in the metabolism pathway. Decreased prostaglandin synthesis in many animal model's cell is caused by presence of Carprofen.

Diflunisal (also known as Dolobid) is a prostaglandin G/H synthase inhibitor that can inhibit prostaglandin G/H synthase 1 and 2 which prevent the production of prostaglandin. Therefore, diflunisal can be used for treating prostaglandin-associated pain, fever, swelling, platelet aggregation and inflammation. Diflunisal can also inhibit the relocation of leukocytes to inflammation site and also the production of the aggregating agent of platelets: thromboxane A2.