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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An analysis of dose and schedule dependence of calcium leucovorin rescue during high-dose methotrexate therapy of ascitic forms of l1210 leukemia and Sarcoma 180 is reported. Schedules with very delayed "low-dose" leucovorin rescue following lethal doses of methotrexate were highly effective in preventing toxicity and achieved a pronounced antitumor effect in both ascites tumor models. Best results were obtained on a schedule of methotrexate (400 mg/kg s.c.) followed 16 to 20 hr later by calcium leucovorin (12 mg/kg s.c.) given once every 2 hr for a total of 5 doses. Progressive increases in the calcium leucovorin dosage on any schedule reduced both toxicity and the antitumor effect of methotrexate in each model. Following a single course of therapy, essentially no toxicity was observed, and the antitumor effects were 2-fold (L1210 leukemia) and 4-fold (Sarcoma 180) greater than a single, maximally tolerated dose (24/kg s.c.) methotrexate alone. An increase in the methotrexate dosage to 800 mg/kg s.c. with or without an increase in calcium leucovorin dosages on the same schedule did not appreciably increase the antitumor effect observed. Two courses of high-dose methotrexate (400 mg/kg s.c.) with leucovorin rescue (24 mg/kg s.c. 16, 20, and 24 hr after drug) given with an 8-day interval between courses doubled the total antitumor effect in each model with no substantial increase in toxicity and gave long-term survivors with Sarcoma 180. The results, overall, are in close agreement with prior prediction for schedule and dose dependence made on the basis of related pharmacokinetic and biochemical studies in murine tumor models reported from this laboratory.
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PMID:Optimization of high-dose methotrexate with leucovorin rescue therapy in the L1210 leukemia and sarcoma 180 murine tumor models. 30 75

Vitreous seeds in retinoblastoma were studied clinically and pathologically. Vitreous seeds were found in 36.6% of retinoblastoma eyes. When tumors involved more than three quadrants of the retina and vitreous seeds were present, the prognosis was poor. When the tumor involved less than one-quarter of the retina, vitreous seeds were rare. Vitreous seeds were found most frequently in cases of undifferentiated tumor cells and endophytum type of proliferation. Although most vitreous seeds were necrotic tumor cells, some were almost intact tumor cells which were apt to be situated along blood vessels. The blood vessels in vitreous seeds had no pericytes and were derived from the tumor itself. Thus it is possible that tumor cells in the vitreous body can migrate to the anterior segment of the eye. Some tumor cells in vitreous seeds had much cytoplasm which contained mitochondria, ribosomes, fibrils, centrioles, and cilia with a presumed photoreceptor outer segment and intercellular junctions. These cytoplasmic features are very similar to those of neuroepithelial-type retinoblastoma cells. Undifferentiated cells were necrotic. Calcium deposition was found mainly in the necrotic cytoplasm of the tumor cells and occasionally on the chromatin granules of the nucleus. This may provide evidence that calcium can be bound to DNA to form radiopaque masses. No calcium-producing cells were found. Vitreous seeds contain a small number of almost intact tumor cells which are neuroepithelial in type, but most cells are necrotic. Although tumor cells may migrate to the anterior segment of the eye along or through blood vessels, the presence of vitreous seeds in itself is not always a bad prognostic sign. The prognosis is probably more closely related to the extent of the invasion of a tumor associated with vitreous seeds.
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PMID:Vitreous seeds in retinoblastoma, clinical significance and ultrastructure. 31 88

Neutron-activation method was employed to determine the concentration of magnium, sodium, chlorine, phosphorus and calcium in different bone tumors. In relation to normal skeletal tissue in tumor tissues higher concentrations of chlorine and sodium but lower concentrations of calcium and phosphorus were found. The greatest changes in the macromolecular content were noted in sarcoma tissues. Bone tumors differ reliably one from the other by concentrations or ratios of macroelements concentrations, this fact may be used for the differential diagnosis.
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PMID:[Bone tumor macroelements]. 36 5

FOR THE PURPOSES OF THIS REVIEW, THE VAST AND INCREASINGLY COMPLEX SUBJECT OF HYPERCALCEMIC DISORDERS CAN BE BROKEN DOWN INTO THE FOLLOWING CATEGORIES: (1) Physiochemical state of calcium in circulation. (2) Pathophysiological basis of hypercalcemia. (3) Causes of hypercalcemia encountered in clinical practice: causes indicated by experience at the University of California, Los Angeles; neoplasia; hyperparathyroidism; nonparathyroid endocrinopathies; pharmacological agents; possible increased sensitivity to vitamin D; miscellaneous causes. (4) Clinical manifestations and diagnostic considerations of hypercalcemic disorders. (5) The management of hypercalcemic disorders: general measures; measures for lowering serum calcium concentration; measures for correcting primary causes-the management of asymptomatic hyperparathyroidism.
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PMID:The pathophysiology and clinical aspects of hypercalcemic disorders. 36 22

A 58-year-old patient with hypergastrinemia (basal and after stimulation by means of protein food, calcium, glucagon, and secretin), acid hypersecretion, recurrent anastomotic ulcer, gastrocolonic fistula, steatorrhea, and malabsortion (hypocalcemia, hypocholesterolemia and a rather elevated 5-HIAA) is reported. The definite preoperative diagnosis of Zollinger-Ellison syndrome was established after the intravenous secretin test (75 U) which produced a significant stimulation peak 5 minutes after being injected. The possible existence of a multiple endocrine adenomatosis syndrome type I was discarded. During the operation no pancreatic or extrapancreatic macroscopic tumor was found. A total gastrectomy, transverse colectomy, splenectomy, and subtotal pancreatic resection were performed; Rosanow's techniques was used to re-established the gastrointestinal continuity. The morphological study of the excised pancreatic tissue showed a diffuse hyperplasia of the Langerhans islet cells; indirect immunofluorescence in the presence of antigastrin antibodies was faintly positive and difficult to evaluate. However, gastrin levels clearly decrease after the operation may be because the inhibitory effect of total gastrectomy or because of the partial pancreatectomy. Furthermore, the inhibitory effect of tyrocalcitonine onthe pre- and postoperative gastrin levels measured by radioimmunoassay could be verified. For the moment the importance of this test in the diagnosis of Zollinger-Ellison syndrome, and especially in the diagnosis of ZES-type II, is not known.
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PMID:[Zollinger-Ellison syndrome type II due to diffuse hyperplasia of the pancreatic islet cells (author's transl)]. 38 7

In a series of experiments the prolonged feeding of rats with thioacetamide and 4-dimethylaminoazobenzene provoked an increase in mitochondrial calcium. It seems likely that this continuous mitochondrial overloading with Ca2+ is related to metabolic and functional changes of the liver cell leading to a neoplastic transformation. The drastic changes in cell membrane permeability of cholangiocarcinoma tumor cells, reflected by an increased concentration of extracellular cations (calcium and sodium), while the intracellular cations tended to decrease, indicate that the mitochondrial function of specification of cell membrane characteristics is possibly impaired by that calcification.
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PMID:Mitochondrial calcium during liver carcinogenesis due to thioacetamide and 4-dimethylaminoazobenzene. 40 4

Medullary carcinoma (MC) of the thyroid, in contrast to papillary-follicular carcinoma, fails to concentrate iodine and thus has not been treated with radioactive iodine. We have successfully treated a 16-yr-old Mexican-American girl with residual MC after maximal thyroidectomy (Tx), utilizing radioiodine (131I) to deliver radiation to residual follicular cells in the tumor bed. Immediately after Tx, plasma thyrocalcitonin levels before and during calcium infusion were all elevated (640--1200 pg/ml). 131I (150 mCi) was administered 12 days after Tx after four daily im injections of bovine TSH. Three months after 131I therapy, thyrocalcitonin levels before and during calcium infusion were all normal (less than 50 pg/ml). Ten months after 131I therapy, thyrocalcitonin levels before and after iv pentagastrin were all normal (less than 60 pg/ml). These results suggest that parafollicular cells are radiosensitive, and that therapeutic levels of radiation can be delivered to these cells after Tx if iodine trapping by the remaining follicular cells is enhanced by high levels of circulating TSH. 131I may be the therapy of choice for MC after Tx, if disease has not spread beyond the area proximate to the thyroid gland.
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PMID:Radioiodine in the treatment of medullary carcinoma of the thyroid. 42 97

Medullary thyroid carcinoma (MTC) is a distinctive neoplasm which is derived from the calcitonin-producing intrathyroidal C-cell system and which develops commonly in untreated rats of various strains. Thyroid glands of Long-Evans rats ranging in age from 3 months to 3 years showed a spectrum of C-cell proliferative abnormalities. As compared to 3-month-old control rats, thyroids from 9- to 12-month-old animals exhibited mild diffuse C-cell hyperplasia (CCH). Thyroids from animals ranging from 1 to 3 years of age exhibited progressively more severe C-cell abnormalities including severe diffuse CCH, nodular CCH, and/or MTC. In contrast to the normal basal serum calcitonin levels in controls and in animals with mild diffuse CCH, animals with severe diffuse CCH, nodular CCH, or MTC had elevated basal serum calcitonin values. Nodular CCH was characterized by the replacement and enlargement of individual follicles by C-cells. Larger foci of nodular CCH were characterized by similar changes in multiple adjacent follicles or by an irregular expansion of individual follicles. MTC was characterized by penetration of the follicular basal lamina by C-cells with extension into the adjacent thyroid stroma. In addition to the high incidence of thyroidal C-cell abnormalities, diffuse and/or nodular parathyroid hyperplasia was commonly found. There was no evidence of chronic renal failure in these animals, and the serum calcium levels were within normal limits. Although the stimulus for the initial C-cell proliferation remains unknown, the appearance of MTC is preceded by relatively prolonged phases of CCH. These findings are essentially identical with those noted in human familial MTC and indicate that the rat provides a useful model system for studying the regulation of C-cell proliferation during the processes of neoplastic development and progression.
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PMID:C-cell hyperplasia and medullary thyroid carcinoma in the rat. An immunohistochemical and ultrastructural analysis. 43 Oct 34

Microtubule protein from Ehrlich ascites tumor cells purified by an in vitro polymerization process in the absence of glycerol and calcium chelators contains several accessory proteins but lacks the high molecular weight proteins which are present in neurotubulin. DEAE-Sephadex chromatography of two-times cycled tubulin removes these nontubulin proteins, resulting in pure tubulin, as critically examined by sodium dodecyl sulfate gel electrophoresis. This tubulin can readily assemble into microtubules in assembly buffer, at low magnesium concentrations, without glycerol and at tubulin concentrations above 0.8 mg/mL. Electron microscopy shows that the tubules are identical with normal microtubules. When the purified tubulin fraction was reduced and carboxymethylated, a significant minor protein component could be observed electrophoretically, migrating between alpha- and beta-tubulin. At present, the identity and function of this protein are not known. The results demonstrate that the in vitro assembly of tubulin from Ehrlich ascites tumor cells does not require high molecular weight proteins or gamma-like factor(s) as has been proposed for the neurotubulin system.
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PMID:Assembly of nonneural microtubules in the absence of glycerol and microtubule-associated proteins. 43 79

Nickel sub-sulphide-induced leiomyosarcomas in rabbit white skeletal muscle were studied by both light and electron microscopy. Two types of tumor cells, small spindle cells and elongated smooth muscle cells, are revealed by light microscopy. Nevertheless, their ultrastructure displays the same general feature. The most differentiated cells have abundant cytoplasmic filaments 7 nm in diameter, kept together in bundles by dense bodies. There also exist many 10 nm filaments and a large number of microtubules. The nuclei have prominent nucleoli with an extensive nucleolonema which form an irregular tridimensional network. Distinct fibrillar nuclear bodies were observed. Sometimes there exist desmosomes or gap junctions. The Golgi apparatus produces coated vesicles with secretory function. In the tumors were generally found the Ni3S2 implantations surrounded by a capsule, the major component of which were collagen fibers, degenerated nuclei and rod-like structures with a transverse periodicity of 15.5 nm. From these observations, several characteristics should be pointed out: 1) Many tumor cells contain large nucleoli and distinct intranuclear inclusions of undetermined nature. 2) The coated vesicles represent a secretory activity of the tumor cells; the coat material is probably used during the formation of cell membranes. Another possible function of coated vesicles could be the sequestering of calcium ions. 3) The rod-like structures in the Ni3S2-including capsule are not of Z-line material. 4) The tumoral stem myoblast in heart and skeletal muscle arise from mesenchymal cells.
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PMID:Nickel sub-sulphide-induced leiomyosarcoma in rabbit white skeletal muscle: a light microscopical and ultrastructural study. 44 36


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