Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.1 (asparaginase)
 2,695 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

L-Asparagine synthetase appears in serum approximately 7 days after the s.c. implantation of 1 X 10(5) cells of Leukemia 5178Y/AR (resistant to L-asparaginase) and increases in activity as the neoplasm grows and metastasizes. The principal source of the enzyme is the primary tumor. After intravranial inoculation of tumor, the rate of leakage of the enzyme is more pronounced than when the subcutaneous, intramuscular, or intraperitoneal routes are used. 1-(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea (NSC 79037), a nitro-sourea effective in the palliation of L5178Y/AR, temporarily halts the influx of enzyme into the blood stream, as does surgical excision of the s.c. tumor nodules. Treatment of mice with L-asparaginase within 24 hr of inoculation of the tumor markedly augments both tumor growth and the rate of penetration of L-asparagine synthetase into the circulation. Several other L-asparagine synthetase into the circulation. Several other L-asparaginase-resistant tumors also were found to spill L-asparagine synthetase into the serum, but the correlation between this phenomenon and the specific activity of the enzyme in homogenates of the tumor was imperfect.
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PMID:L-Asparagine synthetase in serum as a marker for neoplasia. 1 81

Coagulation disorders are common in cancer patients. In patients with solid tumors, a low-grade activated coagulation can result in systemic and cerebral arterial or venous thrombosis. Cancer treatments may also contribute to this coagulopathy, which usually, but not exclusively, occurs in the setting of advanced malignant disease. There may be TIAs or cerebral infarctions. Because of the widespread distribution of cerebral thromboses, there may be a superimposed encephalopathy; sometimes this is the only sign. Concurrent systemic thrombosis is present in many patients and is a useful clue to the diagnosis. In cerebral venous occlusion, the initial symptom is usually a headache. Except for cerebral intravascular coagulation that is unassociated with NBTE, neuriomaging studies usually demonstrate one or more parenchymal infarctions. MRI or MRV may demonstrate venous thrombosis. The laboratory evidence of coagulopathy is difficult to distinguish from the asymptomatic coagulopathy that often accompanies advanced cancer, and the test results must be interpreted cautiously. NBTE can be diagnosed by transesophageal echocardiography. There is no established treatment for the thrombotic coagulopathy associated with cancer, but anticoagulation should be considered. In leukemia and lymphoma, the coagulopathy is typically acute DIC that can lead to systemic and brain hemorrhages. It is especially common in acute myelogenous leukemias. The clinical signs of cerebral hemorrhage are fulminant and may be fatal. The bleeding usually occurs in the brain or subdural compartment, and rarely in the subarachnoid space. The diagnosis can be suspected by the clinical setting and by systemic thrombosis or hemorrhage. It can be established by examination of the peripheral smear, the platelet count, and tests of coagulation function. Therapy of acute DIC is controversial and should be individualized for the clinical setting. Cerebrovascular disorders can complicate metastatic or primary tumor in the brain, skull, dura, or leptomeninges. The clinical signs of infarction are indistinguishable from other causes of stroke, except that tumor-related venous occlusion will usually first produce signs of increased intracranial pressure. The diagnosis of tumor-related infarction can usually be established by neuroimaging studies that show infarction and may show extracerebral sites of tumor. CSF examination is useful in diagnosing leptomeningeal metastasis. A search for lung or cardiac tumor should be performed when embolic tumor infarction is suspected. Primary or metastatic tumors in the brain or dura may hemorrhage, producing the initial clinical signs of the brain tumor or a change in chronic signs induced by the tumor. There are helpful clues to a neoplastic hemorrhage on brain CT or MRI scans. The brain hemorrhage may require evacuation and the underlying tumor will usually require additional antineoplastic treatment. Hyperleukocytosis (extreme elevation of the cell count) in acute myelogenous leukemia is a less common cause of brain hemorrhage in recent years because of improved methods to lower the cell count. Cerebral arterial or venous thrombosis is sometimes the result of cancer therapy. The attribution of thrombosis to chemotherapy in many published cases is only speculative, because carefully conducted prospective studies that include investigation for other thrombotic causes are not available. The best-known associations with thrombosis are L-asparaginase, which is typically used in the induction therapy of acute lymphocytic leukemia, and combination hormonal therapy and chemotherapy for breast cancer. Radiation to the head and neck, typically administered for head and neck epithelial cancers or lymphoma, may result in delayed carotid atherosclerosis. The distribution of stenosis or occlusion is within the radiation portal and is typically more extensive than is atherosclerosis that develops in the absence of radiation. Small clinical series suggest that surgical treatment is equally effective as in nonirradiated carotid atherosclerosis. In children, the cerebral vessels can be affected by brain radiation resulting in stenosis or occlusion. Brain hemorrhages can result from chemotherapy effects on the hemostatic system or a microangiopathic anemia. Hemorrhages from radiation-induced vascular abnormalities are rare. Opportunistic infections, especially fungal infections, can complicate cancer or its treatment. Septic cerebral emboli may result in focal cerebral signs, seizures, or encephalopathy. Sometimes there is an associated hemorrhagic vasculitis or cerebritis. Rarely, mycotic aneurysms may bleed. A high index of suspicion is needed to diagnose fungal infection because of the difficulty in culturing the organism from the blood or CSF. A clinician can usually establish the cause of stroke in the cancer patient by performing a careful review of the clinical setting--including the type and extent of cancer and the type of antineoplastic therapy--in which the stroke occurred. Systemic thrombosis, embolism, or hemorrhage can be a clue to the cause, and appropriate neuroimaging and coagulation studies to aid in the diagnosis are available. Therapy may ameliorate symptoms or prevent further episodes. The identification of one of these unusual stroke syndromes that leads to the diagnosis of an occult and treatable cancer can be particularly rewarding.
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PMID:Cerebrovascular complications in cancer patients. 1269 Jun 49