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Peptide Receptor Radionuclide Therapy
Peptide receptor radionuclide therapy (PRRT) is a type of radionuclide therapy, using a radiopharmaceutical that targets peptide receptors to deliver localised treatment, typically for neuroendocrine tumours (NETs). Mechanism A key advantage of PRRT over other methods of radiotherapy is the ability to target delivery of therapeutic radionuclides directly to the tumour or target site. This works because some tumours have an abundance (overexpression) of peptide receptors, compared to normal tissue. A radioactive substance can be combined with a relevant peptide (or its analogue) so that it preferentially binds to the tumour. With a gamma emitter as the radionuclide, the technique can be used for imaging with a gamma camera or PET scanner to locate tumours. When paired with alpha or beta emitters, therapy can be achieved, as in PRRT. The current generation of PRRT targets somatostatin receptors, with a range of analogue materials such as octreotide and other DOTA compounds. These ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radionuclide Therapy
Radionuclide therapy (RNT, also known as unsealed source radiotherapy or molecular radiotherapy) uses radioactive substances called radiopharmaceuticals to treat medical conditions, particularly cancer. These are introduced into the body by various means (injection or ingestion are the two most commonplace) and localise to specific locations, organs or tissues depending on their properties and administration routes. This includes anything from a simple compound such as sodium iodide that locates to the thyroid via trapping the iodide ion, to complex biopharmaceuticals such as recombinant antibodies which are attached to radionuclides and seek out specific antigens on cell surfaces. This is a type of targeted therapy which uses the physical, chemical and biological properties of the radiopharmaceutical to target areas of the body for radiation treatment. The related diagnostic modality of nuclear medicine employs the same principles but uses different types or quantities of radioph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phaeochromocytoma
Pheochromocytoma (PHEO or PCC) is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes. When a tumor composed of the same cells as a pheochromocytoma develops outside the adrenal gland, it is referred to as a paraganglioma. These neuroendocrine tumors are capable of producing and releasing massive amounts of catecholamines, metanephrines, or methoxytyramine, which result in the most common symptoms, including hypertension (high blood pressure), tachycardia (fast heart rate), and diaphoresis (sweating). However, not all of these tumors will secrete catecholamines. Those that do not are referred to as biochemically silent, and are predominantly located in the head and neck. While patients with biochemically silent disease will not develop the typical disease manifestations described above, the tumors grow and compress the surrounding structures of the head and neck, and can result in pulsatile tinnitus (ringing of the ear), hearing loss, au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bronchial
A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. These are the widest bronchi, and enter the right lung, and the left lung at each hilum. The main bronchi branch into narrower secondary bronchi or lobar bronchi, and these branch into narrower tertiary bronchi or segmental bronchi. Further divisions of the segmental bronchi are known as 4th order, 5th order, and 6th order segmental bronchi, or grouped together as subsegmental bronchi. The bronchi, when too narrow to be supported by cartilage, are known as bronchioles. No gas exchange takes place in the bronchi. Structure The trachea (windpipe) divides at the carina into two main or primary bronchi, the left bronchus and the right bronchus. The carina of the trachea is located at the level of the sternal angle and the fifth thoracic verte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuroendocrine Tumor
Neuroendocrine tumors (NETs) are neoplasms that arise from cells of the endocrine (hormonal) and nervous systems. They most commonly occur in the intestine, where they are often called carcinoid tumors, but they are also found in the pancreas, lung, and the rest of the body. Although there are many kinds of NETs, they are treated as a group of tissue because the cells of these neoplasms share common features, such as looking similar, having special secretory granules, and often producing biogenic amines and polypeptide hormones. Classification WHO The World Health Organization (WHO) classification scheme places neuroendocrine tumors into three main categories, which emphasize the tumor grade rather than the anatomical origin: * well-differentiated neuroendocrine tumours, further subdivided into tumors with benign and those with uncertain behavior * well-differentiated (low grade) neuroendocrine carcinomas with low-grade malignant behavior * poorly differentiated (high grade) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DOTATOC
Edotreotide (USAN, also known as (DOTA0- Phe1- Tyr3) octreotide, DOTA-TOC, DOTATOC) is a substance which, when bound to various radionuclides, is used in the treatment and diagnosis of certain types of cancer. When used therapeutically it is an example of peptide receptor radionuclide therapy. Yttrium-90 A phase I clinical trial of yttrium-90 labelled edotreotide concluded in 2011, aiming to investigated effects in young cancer patients (up to 25 years of age). Specific cancers being included in the trial include neuroblastoma, childhood brain tumours and gastrointestinal cancer. A phase II trial for the use of 90Y DOTA-TOC for patients with metastatic carcinoid, where octreotide treatment was no longer effective, also reported results in 2010. : Lutetium-177 Lutetium-177 labelled edotreotide (177Lu-DOTA-TOC), with the trade name Solucin, is the subject of a phase 3 clinical trial for treatment of GEP-NETs. It was granted orphan drug designation by the European Medicines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DOTATATE
DOTA-TATE (DOTATATE, DOTA-octreotate, oxodotreotide, DOTA-(Tyr3)-octreotate, and DOTA-0-Tyr3-Octreotate) is an eight amino acid long peptide, with a covalently bonded DOTA bifunctional chelator. DOTA-TATE can be reacted with the radionuclides gallium-68 (T1/2 = 68 min), lutetium-177 (T1/2 = 6.65 d) and copper-64 (T1/2 = 12.7 h) to form radiopharmaceuticals for positron emission tomography (PET) imaging or radionuclide therapy. 177Lu DOTA-TATE therapy is a form of peptide receptor radionuclide therapy (PRRT) which targets somatostatin receptors (SSR). In that form of application it is a form of targeted drug delivery. Chemistry and mechanism of action DOTA-TATE is a compound containing tyrosine3-octreotate, an SSR agonist, and the bifunctional chelator DOTA (tetraxetan). SSRs are found with high density in numerous malignancies, including CNS, breast, lung, and lymphatics. The role of SSR agonists (i.e. somatostatin and its analogs such as octreotide, somatuline and va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SSTR5
Somatostatin receptor type 5 is a protein that in humans is encoded by the ''SSTR5'' gene. Somatostatin acts at many sites to inhibit the release of many hormones and other secretory proteins. The biological effects of somatostatin are probably mediated by a family of G protein-coupled receptors that are expressed in a tissue-specific manner. SSTR5 is a member of the superfamily of receptors having seven transmembrane segments. See also * Somatostatin receptor Somatostatin receptors are receptors for the ligand somatostatin, a small neuropeptide associated with neural signaling, particularly in the post-synaptic response to NMDA receptor co-stimulation/activation. Somatostatin is encoded by a CRE ... References Further reading * * * * * * * * * * * * * * * * * * * External links * * G protein-coupled receptors {{transmembranereceptor-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SSTR2
Somatostatin receptor type 2 is a protein that in humans is encoded by the ''SSTR2'' gene. The SSTR2 gene is located on chromosome 17 on the long arm in position 25.1 in humans. It is also found in most other vertebrates. The somatostatin receptor 2 (SSTR2), which belongs to the G-protein coupled receptor family, is a protein which is most highly expressed in the pancreas (both alpha- and beta-cells), but also in other tissues such as the cerebrum and kidney and in lower amount in the jejunum, colon and liver. In the pancreas, after binding to somatostatin, it inhibits the secretion of pancreatic enzymes. During development, it stimulates neuronal migration and axon outgrowth. The somatostatin receptor 2 is expressed in most tumors. Patients with neuroendocrine tumors that over-express the somatostatin receptor 2 have an improved prognosis. The over expression of SSTR2 in tumors can be exploited to selectively deliver radio-peptides to tumors to either detect or destroy them. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanreotide
Lanreotide, sold under the brand name Somatuline among others, is a medication used in the management of acromegaly and symptoms caused by neuroendocrine tumors, most notably carcinoid syndrome. It is a long-acting analogue of somatostatin, like octreotide. Lanreotide (as lanreotide acetate) is manufactured by Ipsen. It is available in several countries, including the United Kingdom, Australia and Canada, and was approved for sale in the United States by the Food and Drug Administration (FDA) on August 30, 2007. Medical uses Lanreotide is used in the treatment of acromegaly, due to both pituitary and non-pituitary growth hormone-secreting tumors, and the management of symptoms caused by neuroendocrine tumors, particularly carcinoid tumors and VIPomas. In the United States and Canada, lanreotide is only indicated for the treatment of acromegaly. In the United Kingdom, it is also indicated in the treatment of thyrotrophic adenoma, a rare tumor of the pituitary gland which s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somatostatin Receptor
Somatostatin receptors are receptors for the ligand somatostatin, a small neuropeptide associated with neural signaling, particularly in the post-synaptic response to NMDA receptor co-stimulation/activation. Somatostatin is encoded by a CRE and is very susceptible to gene promoter region activation by transcription factor CREB. There are five known somatostatin receptors: * SST1 () * SST2 () * SST3 () * SST4 () * SST5 () All are G protein-coupled seven transmembrane receptor G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of protein family, evolution ...s. References External links * G protein-coupled receptors {{transmembranereceptor-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triazacyclononane
1,4,7-Triazacyclononane, known as "TACN" which is pronounced "tack-en," is an aza-crown ether with the formula (C2H4NH)3. TACN is derived, formally speaking, from cyclononane by replacing three equidistant CH2 groups with NH groups. TACN is one of the oligomers derived from aziridine, C2H4NH. Other members of the series include piperazine, C4H8(NH)2, and the cyclic tetramer 1,4,7,10-tetraazacyclododecane. Synthesis The ligand is prepared from diethylene triamine as follows by macrocyclization using ethyleneglycol ditosylate. :H2NCH2CH2NHCH2CH2NH2 + 3 TsCl → Ts(H)NCH2CH2N(Ts)CH2CHH2N(H)Ts + 3 HCl :Ts(H)NCH2CH2N(Ts)CH2CH2N(H)Ts + 2 NaOEt → Ts(Na)NCH2CH2N(Ts)CH2CH2N(Na)Ts :Ts(Na)NCHH2CH2N(Ts)CH2CH2N(Na)Ts + TsOCH2CH2OTs + → CH2CH2N(Ts)sub>3 + 2 NaOTs : CH2CH2N(Ts)sub>3 + 3 H2O → H2CH2NHsub>3 + 3 HOTs Coordination chemistry TACN is a popular tridentate ligand. It is threefold symmetric and binds to one face of an octahedron of metalloids and transition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
