Amine precursor uptake and decarboxylation

Amine precursor, uptake and decarboxylation cell from which the platelet is derived. 

These tumours generally grow slowly. They develop from the neuroendocrine system, which is considered to be part of the APUD system (= amine precursor uptake and decarboxylation) (A.G.E. Pearse et al., 1978). However, due to the secretion of biologically active hormones, they give rise to manifold clinical symptoms. Such tumours very seldom develop primarily in the liver. They meanwhile present a real diagnostic challenge for today s sophisticated imaging procedures. (297)... 

Also found in other APUD (amine precursor uptake and decarboxylation) tumors. 

Enolase is a glycolytic enzyme also known as phosphopyru-vate hydratase. Neuron-specific enolase (NSE) is the form of enolase found in neuronal tissue and in the cells of the diffuse neuroendocrine system and the amine precursor uptake, and decarboxylation (APUD) tissue. NSE is found in tumors associated with the neuroendocrine origin, including small cell lung cancer (SCLC), neuroblastoma, pheochromocytoma, carcinoid, medullary carcinoma of the thyroid, melanoma, and pancreatic endocrine tumors. 

APUD (amine precursor uptake and decarboxylation) cells are derived from the neuroblast (stem cells that give rise to nerve cells and neural crest cells) or the entoderm. They have the ability to synthesize and release peptide hormones and, as their name implies, take up amine precursors (e.g., dopa) and decarboxylate them, producing hormonal amines (e.g., dopamine). 

Caillaud JM, Benjelloun S, Bosq J, et al. HNK-l-defined antigen detected in paraffin-embedded neuroectoderm mmors and those derived from cells of the amine precursor uptake and decarboxylation system. Cancer Res. 1984 44 4432-4439. 

Matsuki and colleagues evaluated histidine decarboxylase, an enzyme of the amine precursor uptake and decarboxylation system known to be distributed in mast cells and enterochromaffin-like cells, with the hypothesis that this enzyme was a marker for neuroendocrine differentiation. The authors found that the anti-histidine decarboxylase antibody stained most small cell lung cancers (18 of 23 sensitivity 0.78) and was rarely reactive with non-neuroendocrine lung tumors... 

CftjHsgNigOijS, Mr 1347.64, crystals from aqueous acetic acid as the triacetate tetrahydrate, [a S -76° (5% acetic acid), a peptide hormone produced in APUD cells (from amine precursor uptake and decarboxylation) of... 

NET cells are characterized by their ability to take up and concentrate amine precursors such as dihydroxy-phenylalanine (DOPA) and hydroxytryptophane (HTP) and to produce amines and peptides, for which reason they were also classified as amine precursor uptake and decarboxylation (APUD) cells. They may also express different peptide hormone receptors (like somatostatin receptors) or transporters at their cell membrane. These uptake mechanisms and the presence of peptide receptors and transporters constitute the basis for the use of specific radiolabeled ligands for imaging of neuroendocrine tumors. 

Carcinoids are the most common tumors arising from the diffuse neuroendocrine system of the GI tract and pancreas. Derived primarily from enterochromaffin cells, these tumors are widely distributed in the body but found with greatest frequency in the GI tract (74%) and respiratory tract (25%). Carcinoids are often classified as APUDomas (flmine precursor uptake and decarboxylation) because of the ability of enterochromaffin cells to take up and decarboxylate amino acid precursors of biogenic amines. In this regard, carcinoid tumors share certain pathological and biological similarities with pheochromocytomas. 

APUD amine-precursor-uptake-decarboxylation cells (peptide- and amine-storing cells) are a diverse group, embryologically of neural crest origin that are characterized by these cytochemical characteristics they secrete amine and/or peptide mediators at one extreme they may be released into the bloodstream to act at a distance (i.e. endocrine action) and at the other to act locally at an adjacent cell (paracrine action). See local homones. 

Pearse (60) reported that type I cells of the carotid body resemble the amine precursor uptake decarboxylation (APUD) cell system and suggested that they secrete a polypeptide, provisionally named glomin, that could be important in chemoreception. Now it is well recognized that carotid bodies express a variety of peptides that serve as transmitters or modulators elsewhere in the nervous system (Table 1). 

The BA biosynthetic pathways are generally composed of a transport protein embedded in the cytoplasmic membrane, which is responsible for both the uptake of the precursor and the secretion of the BA and a metabolic enzyme, which converts an amino acid into the corresponding amine by a decarboxylation reaction (Figure 12.1(a)). Exceptions are the putrescine biosynthetic pathways from agmatine or arginine, in which several enzymes are required for production of this BA (Figure 12.1(b)). 

---