Somatostatin-receptor imaging for the detection of tumors

Article Abstract:

Somatostatin was first discovered as a hypothalamic peptide hormone which inhibited growth hormone. Since that time, the substance has been found to play a role in a wide array of different organs and cell types, though most cells which express somatostatin receptors are neurons or endocrine cells. The potential pharmacologic usefulness of somatostatin was limited by its instability and short half-life within the body. However, the structure of somatostatin was amenable to chemical modification and pharmacologists soon produced a number of somatostatin analogues, including octreotide. Octreotide can bind to somatostatin receptors, and is more stable than somatostatin. The compound has been therapeutically used in the treatment of several endocrine tumors, such as carcinoids, pancreatic endocrine tumors, and some pituitary adenomas. Octreotide does not destroy tumor cells, but can provide important palliative relief by suppressing the abnormal secretion of hormones by these tumors. However, researchers have recently shown that the binding of octreotide may also be used as an imaging method capable of demonstrating the location of metastatic tumors with a high degree of precision. The researchers, who presented their results in the November 1, 1990 issue of The New England Journal of Medicine, injected tiny quantities of radioactively labelled octreotide into patients with carcinoids or pancreatic tumors. Some of the octreotide bound to somatostatin receptors on the tumor cells, the rest was rapidly cleared from the body. A camera then revealed the location of the radioactive sources, that is, the tumors which have bound the octreotide. This method results in some false negatives, since not all tumor cells necessarily express somatostatin receptors on their cell surface. However, a great many different types of tumor cells do, including some non-endocrine tumors including astrocytomas, small-cell lung cancers, and some breast cancers. This exciting technique is likely to find application for imaging in many other conditions and the method seems destined to receive wider use as our knowledge of cell receptor physiology grows. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Diagnosis, Hormone receptors, Tumors, Diagnostic imaging, Medical imaging equipment, Carcinoid, Carcinoid tumor, editorial, Pancreatic tumors, Radioisotopes in medical diagnosis, Radioisotopic diagnosis

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DNA sequences similar to those of Simian virus 40 in ependymomas and choroid plexus tumors of childhood

Article Abstract:

Ependymomas or choroid plexus tumors, two different types of brain tumors that occur in young children, may be caused by simian virus 40 (SV40), the monkey polyomavirus, or a related virus. The DNA (gene) sequence of tumors from 31 children, 20 with choroid plexus tumors and 11 with ependymomas, was analyzed and compared to the T antigen gene of the SV40 virus and the BK and JC viruses, two types of polyomavirus that occur in humans. Ten of the choroid plexus tumors and 10 of the ependymomas contained DNA sequences that were similar to segments of the T antigen gene of the SV40 virus, but not the BK or JC virus. The DNA sequence of two of these specimens was identical to a portion of the T antigen gene of the SV40 virus. Three of the specimens that were similar to the SV40 virus contained the 574-bp segment of the T antigen gene of the SV40 virus. Special stains revealed that seven of 11 tumor samples contained the T antigen of the SV40 virus.

Health aspects, Causes of, Brain tumors, Tumors in children, Pediatric tumors, Papilloma, Papillomas, SV40 (Virus), Simian virus type 40

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Chorionic tumors

Article Abstract:

Chorionic tumors originate from placental tissue. They include complete and partial molar pregnancy, placental-site trophoblastic tumor and choriocarcinoma. Ultrasound scanning can diagnose a molar pregnancy, which is usually treated surgically. Persistent gestational trophoblastic tumors can develop following a molar pregnancy and some physicians believe chemotherapy can reduce the risk. CT scans of the head, chest and pelvis can detect metastatic cancer. Patients should be treated with methotrexate or dactinomycin or a combination of drugs.

Care and treatment, Pregnancy, Molar, Molar pregnancy, Trophoblastic tumors

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