Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A Mg2+- and Ca2+-stimulated adenosine triphosphatase (ATPase) at the outer surface of intact Ehrlich ascites tumor cells is described. A surface-bound adenosine triphosphate (ATP)-splitting activity at a lower rate was also demonstrated in the absence of Ca2+ but with Mg2+, Na+, and K+ present in the isotonic medium. Hence, when part of the Mg2+ was exchanged for Ca2+, a marked increase of the ATP-splitting activity was observed. The stimulatory effect of Ca2+ was seen only if both Na+ and K+ were present in the isotonic incubation medium. Thus, the enzyme activity was Mg2+- and Ca2+-dependent. Ca2+, together with the monovalent cations was inhibitory compared with Mg2+ under similar conditions. The apparent Km for ATP for the Mg2+-stimulated ATPase is 0.05 mM, while that of the Mg2+- and Ca2+-stimulated enzyme is 0.10 mM. The Vmax of the former is 0.8 mu-mole per 100 mg Schneider protein per 30 sec compared with 1.92 mu-moles per 100 mg Schneider protein per 30 sec for the latter. The calculated Km for the Mg2+- and Ca2+-stimulated ATPase after subtraction of the Mg2+-stimulated part is 0.22 mM. Ethacrynic acid and N-ethylmaleimide both inhibited the Mg2+- and Ca2+-stimulated ATPase by about 10 percent, while the ouabain inhibition was 15 percent. Cytochalasin B did not influence the enzyme activity, whereas La3+ had a slight stimulatory effect.
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PMID:A Mg2+- and Ca2+-stimulated adenosine triphosphatase at the outer surface of Ehrlich ascites tumor cells. 12 5

A patient with metastatic islet cell carcinoma of the pancreas, recurrent peptic ulcer disease, and hypergastrinemia (Zollinger-Ellison syndrome) developed symptomatic hypercalcemia and renal insufficiency; she was treated with streptozotocin after parathyroidectomy failed to control her hypercalcemia. Shortly after somewhat less than the usual recommended dose of streptozotocin was administered, the serum calcium concentration fell to near normal with complete resolution of symptoms. Seven months after therapy, mild hypocalcemia, consistent with her degree of renal impairment was noted. However, mild hypercalcemia recurred 13 months after therapy. Shortly after streptozotocin therapy, the mean serum gastrin concentration fell to near normal with radiographic disappearance of the anastomotic ulcer. At 7 and 13 months after therapy, serum gastrin levels were normal. Streptozotocin therapy was accomplished without major complications; specifically, without a detrimental effect on the creatinine clearance. Thus, although hypercalcemia in patients with pancreatic islet cell tumors is often due to associated primary hyperparathyroidism, in some patients it may be due to secretion of a hypercalcemic substance from the tumor and may respond to streptozotocin. Similarly, hypergastrinemia in patients with islet cell tumors may also respond to streptozotocin.
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PMID:Pancreatic islet cell carcinoma with hypercalcemia and hypergastrinemia: response to streptozotocin. 13 70

Twelve parathyroid chief cell adenomas from patients with primary hyperparathyroidism were incubated in a tissue culture system in the presence of different calcium concentrations and for various time periods. The endocrine response of the tissue was examined electron microscopically and radioimmunologically. After incubation in a medium of low calcium concentration the parathyroid adenomas showed ultrastructural signs of stimulation with proliferation of the hormone-synthesizing organelles. The development of the ultrastructural response could first be observed after four hours and increased up to several days. Radioimmunologically, an increase of the hormone secretion could be demonstrated. Converse results were obtained after incubation of the tumor tissue under suppressive culture conditions. To check for de-novo synthesis of the hormone released the tissue was incubated in a 75Se-methionine-containing medium. This resulted in radioactivity of the secreted parathyroid hormone, indicating de novo synthesis in our culture system. The biological potency of the released hormone was demonstrated by comparison of the PTH out of the medium with the international human MRC standard using two different radioassays.
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PMID:Correlation of electron microscopic and secretory response of human parathyroid adenomas with different calcium concentrations in organ culture. 15 Jan 11

Ca2+ uptake into Ehrlich ascites tumor cells was studied at 0 degrees C in the presence of mitochondrial inhibitors, conditions that minimized complications caused by sequestration of Ca2+ into organelles or by excretion. Under these conditions Ruthenium Red inhibited Ca2+ uptake, but other previously implicated ions, such as Pi or Mg2+, had no effect. Valinomycin either inhibited or slightly stimulated Ca2+ uptake depending on the presence of excess K+ on the outside or inside of the cell, respectively. Nigericin inhibited Ca2+ transport. Based on these data we propose an electrogenic uptake of Ca2+, possibly via a Ca2+/H+ antiport mechanism. The observation that glucose inhibited Ca2+ uptake suggested that in Ehrlich ascites tumor cells an energy-driven Ca2+ expulsion mechanism is operative, similar to that in erythrocytes. Plasma membrane preparations of ascites tumor cells were found to contain a Ca2+-dependent ATPase. These preparations, when incorporated into liposomes in an inside-out orientation, catalyzed an ATP-dependent uptake of Ca2+.
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PMID:Ca2+ translocation in Ehrlich ascites tumor cells. 15 90

Hypercalcemia calls first for supportive measures, eg, adequate hydration, movement or mobilization of the patient to the greatest amount tolerated, and reevaluation of drugs being taken. When immediate lowering of the serum calcium level is not clinically mandatory, oral administration of furosemide, corticosteroid, or phosphorus should be considered. In acute emergencies, saline loading and parenteral furosemide therapy should be tried first, except in a patient with renal failure and congestive heart failure, in whom peritoneal dialysis or hemodialysis should be used instead. Calcitonin can be given for the first 12 to 24 hours to lower serum calcium concentration until a definitive management plan is formulated. Corticosteroid, if not contraindicated, should be started as soon as possible. In severe primary hyperparathyroidism with hypophosphatemia, phosphorus can be given intravenously until oral phosphate therapy can be established. Surgery, of course, should be performed as soon as possible. In most cases of neoplasia, mithramycin given according to a recommended schedule is safe and frequently effective. In desperate cases, additional use of prostaglandin synthesis inhibitors probably now is justified by empirical observations. All of these therapeutic measures are used only to stabilize electrolyte balance so that the primary cause of the hypercalcemia can be treated.
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PMID:Management of hypercalcemia. 15 84

The formation of cellular aggregates (foci) in CV-1 cells following infection with Yaba tumor poxvirus is dependent upon cell passage level, temperatue of incubation, and calcium concentration in the medium. Resistance of older cells can be reversed by maintaining calcium at 0.1 mM or by adding cortisone acetate (1 mug/ml), hydrocortisone, or estradiol-17beta to the cultures. In susceptible cells, foci formation was inhibited slightly by methyltestosterone and inhibited completely by dexamethasone, aldosterone and progesterone. Activities and patterns of enzymes associated with cytoplasmic membranes (alkaline phosphatase, mononucleotidase, and Na+-K+-adenosine triphosphatase) and lysosomes (beta-glucuronidase and acid phosphatase) of the younger susceptible and the older resistant CV-1 cells differed. These differences apparently occurred in concert with phenotypic changes in the membranes that reduced the mobility of older resistant cells. In susceptible culture, unifected cells migrated to the infected cell and participated in foci formation. Reduction of the calcium content to 0.1 mM apparently removed some of the constraints on mobility of the resistant cells. Although the hormones may have had a similar effect, the changes in enzyme patterns indicated basic alterations in protein synthesis. The development of resistance to foci formation occurred between the 45th and 50th passage level. Hormonal reversal of this resistance resulted in enzyme profiles that reflected the pattern of young susceptible cells.
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PMID:Alterations of enzymes associated with plasma membranes and cellular organelles during infection of CV-1 cells with Yaba tumor poxvirus. 16 62

Growth characteristics, survival time, sex differences and hormonal effects, and various biochemical parameters were evaluated in a transplantable Furth/Wistar rat Wilms' tumor model. Survival time was dependent on site of tumor transplant and ranged from a mean of 28 days for intrarenal implantation to 44 days intramusculary. Maximum tumor weight (130 g) was obtained via subcutaneous implant. Lung metastasis was evident in the majority of animals with the exception of those receiving the tumor implant intraperitoneally. The levels of erythropoietin and serum calcium and phosphatase were comparable to control values whereas hematocrit levels declined. Tumor tissue arginase or total protein remained unchanged during tumor growth. In these same tissues DNA, content and 5-alpha-reductase activity significantly and progressively increased with concomitant tumor growths. Measurements of lactic dehydrogenase, alkaline phosphatase, and their isoenzymes indicated patterns of liver involvement which were not macroscopically evident. After 31 days of subcutaneous tumor transplant, male and female rats had tumors of comparable weights. Orchiectomy or estradiol treatment significantly reduced tumor weight in males. In female rats testosterone treatment significantly increased tumor weights. DNA concentration in tumor tissue was unaffected by treatment. Similiarly, although 5-alpha-reductase activity was higher in tumors from males, and arginase higher in females, these enzymes were not affected by surgical or hormonal treatment.
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PMID:Characterization of a Wilms' tumor model. 16 21

Between August 1973 and April 1974 more than 750 patients had computerized axial tomography (CT) scans at the Massachusetts General Hospital. Ten brains from previously CT-scanned patients in this group were sectioned in the plane of the scan. Nearly exact correlation was found between the anatomic location and extent of intracranial lesions demonstrated by CT scan and the findings on gross and microscopic pathologic examination in cases of primary intracranial tumors, obstructive hydrocephalus, intracerebral hemorrhage, ischemic and hemorrhagic infarctions, pineal tumor, and thermal-burn encephalopathy. Determination of absorption values (mu) of 47 pathologically verified processes showed that high-absorption intracerebral hemorrhage and calcium-containing tumors are readily separable from other processes on the basis of mu values alone. However, the abnormal mu values of primary brain tumor, edema, and infarction are difficult to distinguish from those of normal spinal fluid and white matter.
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PMID:Computerized axial tomography: clinicopathologic correlation. 16 48

Increasing numbers of endocrine active tumors are being reported. The production of hormonal substances not generally associated with the tissues involved may directly or indirectly concern the gynecologist. Identification of these occurrences may be important in the diagnosis of occult neoplasms or obscure tumor effects. In addition, observation of the level of aberrant hormone secretion may be important therapeutic and prognostic measure. Detection may result from the investigation of apparent inappropriate and endocrine syndromes or routine screening in cases of known tumors. Proof of the actual production of hormone by the tumors and complete identification of the material in question generally requires extensive biologic, chemical, physical, and immunologic investigation. The most likely mechanisms for aberrant hormone production by tumors are derepression of the genome or the occurrence of chance biosynthetic anomalies coincident with neoplastic nuclear alterations. Endocrine active substances of interest to the gynecologist produced under these circumstances include gonadotropin, lactogens, thyrotropins, and adrenocortico-tropin, as well as calcium-mobilizing and erythropoietic substances.
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PMID:Aberrant hormone activity by tumors of gynecologic importance. 16 84

Functioning tumors of the pancreatic islets are now recognized as the source of clinical syndromes affecting the gastrointestinal tract which have a wide variety of catastrophic symptoms. Experiences with thirty-six cases suggest at least four separate diagnostic categories in the ulcerogenic tumor syndrome. These include: a typical history, gastric analysis, and roentgenographic findings with boderline fasting serum gastrin levels; ulcerogenic tumor with evidence of hyperparathyroidism; iatrogenic ulcerogenic syndrome associated with failure of a previous operation for duodenal ulcer; and the classic ulcerogenic syndrome associated with a fulminating ulcer diathesis or diarrhea and high serum gastrin levels. The problems presented at operation include: decisions to be make in the presence of a negative exploration; the finding of a solitary tumor in the wall of the duodenum; solitary pancreatic tumors particularly in the body and tail; ulcerogenic tumors in the very young; liver metastases in the elderly; and the wisdom of removing gross metastases in combination with total gastrectomy. The long-term survival in the ulcerogenic tumor syndrome approximated 50 per cent, with 40 per cent of those having proved malignancy living five years. Evidence of hyperparathyroidism is relatively common in association with both the ulcerogenic and the diarrheogenic tumor syndromes. The association may by a result of a congenital abnormality, metabolic alkalosis, or a direct effect of the islet cell tumor. Parathyroidectomy may be indicated when both the serum calcium and parathormone levels are elevated in the presence of borderline fasting gastrin levels. The latter may return to normal after parathyroidectomy. The evidence of hyperparathyroidism closely parallels the episodes of diarrhea in the diarrheogenic syndrome, and hyperparathyroidism may regress spontaneously after total removal of the pancreatic tumor. Just as routine calcium determinations made the diagnosis of hyperparathyroidism more commonplace, it is suggested that the gastrointestinal syndromes associated with islet cell tumor would receive wider recognition if radioimmunoassays for gastrin as well as secretin, and the other secretin-like polypeptides, were carried out routinely.
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PMID:Islet cell tumors of the pancreas and the alimentary tract. 16 36


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