Viruses tumor-causing

Oncogenes Are Frequently Associated with Tumor-Causing Viruses... 

Following identihcation of the Rous sarcoma virus, a substantial number of additional tumor-causing (oncogenic) viruses have been identified. We are left with the key question of how to reconcile two observations on the one hand, chemicals or chemical substances cause cancer, on the other hand, viruses cause cancer. These observations split the oncology community into two camps. As frequently happens in science, neither camp had the full story and the two opposing viewpoints proved to be entirely compatible. 

Src kinase was discovered during the search for the tumor-causing principle of retroviruses. The viral oncogene product of these viruses, v-Src kinase, was the first tyrosine kinase to be identified. In comparison to its cellular coimterpart, c-Src kinase, v-Src lacks the autoinhibitory structural element that controls protein kinase activity. As a consequence of this loss, v-Src kinase is constitutively active and is a potent transforming protein. 

The term oncogene was coined in association with the search for the tumor-causing principle in retroviruses. Retroviruses contain RNA as the genetic material and can transcribe RNA into DNA with the help of the virus s own enzyme reverse transcriptase. The DNA form of retroviruses can integrate into the DNA of the host cell and, during cell division, is passed on to the daughter cells as a provirus. From the provirus, viral RNA and complete virus particles may be formed. 

Some representatives of the retroviruses cause tumors in animals such as mice or chickens. The discovery of oncogenes initiated from the src gene of Rous sarcoma virus, which could be identified as the tumor causing principle of this retrovirus. The src gene codes for the Src tyrosine kinase (see 8.3). The gene sections of retroviruses responsible for tumor formation were designated oncogenes. 

Mechanisms that may be involved in the induction of cancer by radiation have been proposed. These mechanisms include (1) the induction of mutations, (2) the activation of oncogenes, (3) the inactivation of tumor suppressor genes, and (4) the induction of cancer-causing viruses. Although the relative importance of the various mechanisms in the induction of cancer is not clear, more than one mechanism could be involved for a given type of cancer. 

Sinkovics JG. The causative viruses of murine leukemia and their identification through immune responses of the host Addition. In Carcinogenesis A Broad Critique. The University of Texas M.D. Anderson Hospital and Tumor Institute, Houston, Texas 1967 pp 157-175. 

The value of amino acids as raw materials for the preparation of surfactants was recognized as soon as they were discovered early in the last century. Initially they were used as preservatives for medical and cosmetic applications [1]. Moreover, they were found to be active against various disease-causing bacteria, tumors, and viruses [2 ]. The combination of polar amino acids/... 

Table 6. Some Tumor Viruses Which Cause Cellular Transformation...

For nearly 80% of patients with epilepsy, the underlying etiology is unknown.8 The most common recognized causes of epilepsy are head trauma and stroke. Developmental and genetic defects are the cause of about 5% of cases of epilepsy. Central nervous system (CNS) tumors, central nervous system infections, and neurodegen-erative diseases are other common causes. Other important causes of epilepsy are human immunodeficiency virus infection or neuro-cysticercosis infection, primarily occurring in Latin America. 

Albumin. Albumin is available in highly pure and uniform form, and exhibits low toxicity and good biological stability. It has been used as a carrier for methotrexate and a variety of antiviral drugs [amantadine, fioxuridine (5-fluorodeoxyuridine), and cytar-abine (cytosine arabinoside)] to treat macrophage tumors and infections caused by DNA viruses growing in macrophages. Heavily modified albumins are known... 

Although the ability of viruses to cause tumors in animals has been proved for many years, the relationship of viruses to cancer in... 

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