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

An extremely rare case of psammomatous calcification in a nonfunctioning duodenal carcinoid tumor was studied by light and electron microscopy. The psammoma bodies were found most frequently within the lumina of the neoplastic glands. The ultrastructural features of the psammoma bodies were the marginal needle-shaped crystals and a coarse granular matrix in which a few organelles were embedded. The psammoma bodies appeared to be occasionally intracytoplasmic in position, showing no distinct limiting cytoplasmic membrane. Electron probe x-ray microanalysis revealed that the needle-shaped crystals contained calcium. The mechanism by which the psammoma bodies are formed has not been clearly explained. The above findings support the view that the psammoma bodies may occur initially in the cytoplasm of the tumor cells, followed by their release probably in a way of active excretion.
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PMID:Duodenal carcinoid (apudoma) with psammoma bodies: a light and electron microscopic study. 44 38

The interaction of Ca2+ with Morris hepatoma 3924A mitochondria and its effect on the adenine nucleotide translocation have been studied. The characteristics of the Ca2+ transport process in mitochondria from Morris hepatoma are not significantly different from those of normal liver mitochondria. The Km for Ca2+ is 2 to 3 microM, and the rate versus concentration curve exhibits hyperbolic kinetics. A lower activity of the adenine nucleotide translocation was found, probably due to the high endogenous Ca2+ content of Morris hepatoma mitochondria (123 +/- 15 nmol Ca2+ per mg protein). No further inhibition of the translocase activity was observed after isolated mitochondria had accumulated extra amounts of Ca2+. The total amount of adenine nucleotides in tumor mitochondria is one-half those present in control liver, and a significantly lower percentage of the pool is present as adenosine 5'-monophosphate.
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PMID:Calcium transport and translocation of adenine nucleotides in mitochondria from Morris hepatoma 3924A. 44 77

A calcium-binding protein was detected in the cytosol of Morris hepatomas 7288, 5123tc (h), 5123tc, and 7795. This protein could not be detected in adult Buffalo liver, 24-hr regenerating liver, or 18- to 20-day-old fetal liver. The amount of this protein present was not clearly related to the growth rate of the tumors studied, although there was more in a faster growing tumor (5123tc) than in the slowest (7795). The protein from the four tumors was apparently identical. The calcium-binding protein was heat stable and was not the calcium-dependent regulator of cyclic nucleotide phosphodiesterase. It had an apparent molecular weight of less than 12,500.
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PMID:Occurrence of a low-molecular-weight calcium-binding protein in neoplastic liver. 45 85

Ehrlich ascites tumor cell extracts form a gel when warmed to 25 degrees C at pH 7.0 in sucrose solution, and the gel rapidly becomes a sol when cooled to 0 degrees C. This gel-sol transformation was studied quantitatively by determining the volume or the total protein of pellets of gel obtained by low-speed centrifugation. The gelation depended on nucleotide triphosphates, Mg2+, KCl, and a reducing agent. Gelation was inhibited reversibly by 0.5 microM free Ca2+, and 25--50 ng/ml of either cytochalasin B or D, but it was not affected by 10 mM colchicine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that the gel was composed of six major proteins with mol wt greater than 300,000, 270,000, 89,000, 51,000, 48,000, and 42,000 daltons. The last component was identified as cell actin because it had the same molecular weight as muscle actin and bound with muscle myosin and tropomyosin. The role of actin in gelation was studied by use of actin-inhibitors. Gelation was inhibited by a chemically modified subfragment-1 of myosin, which binds with F-actin even in the presence of ATP, and by bovine pancreatic DNase I, which tightly binds with G-actin. Muscle G-actin neutralized the inhibitory effect of DNase I when added at an equimolar ratio to the latter, and it also restored gelation after its inhibition by DNase I. These findings suggest that gelation depends on actin. However, the extracts showed temperature-dependent, cytochalasin-sensitive, and Ca2+-regulated gelation as did the original extracts when the cell actin in the extracts was replaced by muscle actin, suggesting that components other than cell actin might be responsible for these characteristics of the gelation.
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PMID:The role of actin in temperature-dependent gel-sol transformation of extracts of Ehrlich ascites tumor cells. 45 53

A 17-year-old woman manifested fever, abdominal pain, headache, and hypertension caused by a solitary, benign pheochromocytoma. She also had hypercalcemia and elevated plasma immunoreactive calcitonin levels. After removal of the pheochromocytoma, calcium and calcitonin levels returned to normal. Studies of peripheral and tumor venous blood showed no excess or ectopic parathyroid hormone secretion, but the tumor contained and secreted calcitonin. Sporadic pheochromocytoma may secrete calcitonin and cause hypercalcemia by non-parathyroid hormone-mediated mechanisms. The potential is clearly present for confusion with multiple endocrine neoplasia, type 2 (medullary thyroid carcinoma, pheochromocytoma, and primary hyperparathyroidism).
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PMID:Pheochromocytoma associated with hypercalcemia and ectopic secretion of calcitonin. 46 64

A study is presented of 14 patients with hyperparathyroid crisis treated at the Massachusetts General Hospital between 1964 and 1978. These patients showed diverse clinical manifestations that were indistinguishable from those in patients with pseudohyperparathyroidism. Their symptoms varied from progressive fatigue, malaise, and weakness to those related to the gastrointestinal and urinary tracts. The one biochemical alteration commonly found among these patients was the rapid increase in the serum calcium. There was a concomitant rise in the BUN in 50% of the patients and in the creatinine in 80%. The diagnosis was established by an elevated immunoreactive parathyroid hormone (PTH) level in all eight patients (100%) who had the radioimmunoassay; by the presence of subperiosteal resorption of the phalanges in six of the eight patients (75%); and in three of four patients (75%) by the loss of the lamina dura of the teeth. The 12 patients who had surgery all survived; the two who did not died. Thirteen patients (93%) had a neoplasm--an adenoma in 12 and a carcinoma in one. One patient had hyperplasia (7%). Nine patients (64%) received hypocalcemic drug therapy. The serum calcium temporarily fell to 12 mg/100 ml in five patients (56%) but failed to budge in four (44%). Simultaneous treatment with saline infusion, furosemide and with hypocalcemic drugs over a prolonged period compounded the difficulty at operation by increasing interstitial edema. Our findings from this study show prompt surgical intervention as the ideal treatment for hyperparathyroid crisis, preferably, within 72 hours of the acute onset of symptoms.
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PMID:Hyperparathyroid crisis: clinical and pathologic studies of 14 patients. 51 79

Rapid and preferential uptake of 47 calcium 87m Strontium by the multinodular calcareous masses was seen in a patient with tumoral calcinosis. Using 87m Strontium, scintigraphic imaging of the tumors was achieved, while the skeleton was barely visible. More intense accumulation of 87m Sr. in one tumor suggested a higher rate of calcium depostion. This was in agreement with the observation that this tumor showed less tendency to decrease in size during calcium and phosphorus deprivation therapy. Quantitative measurements of the uptake of bone seeking tracers by the tumors may be of value in estimating calcium turnover in the calcified masses.
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PMID:Tumoral calcinosis: accumulation of bone-seeking tracers in the calcium deposits. 52 Mar 55

Growth inhibition of DS sarcomas provoked by calcitonin treatment is accompanied by an increase of calcium and magnesium in the phospholipid fraction. Changes in tumor cell membrane characteristics reflected in ionic or molecular transport modifications seem to be involved in the growth impairment phenomenon.
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PMID:Divalent cation-phospholipid complexes and tumor growth inhibition. 52 Apr 94

The interaction of hematoporphyrin IX and two synthetic porphyrin tumor localizers, meso-tetra (4-carboxyphenyl) porphine (TCPP) and mesotetra (4-sulfonatophenyl) porphine (TPPS4) with fibrinogen was investigated in the presence and absence of light. Both TPPS4 and TCPP were found to bind to fibrinogen in greater than a 1/1 mole ratio in the absence of light. Chromatographic analysis indicated that during illumination TPP4 bound to fibrinogen to a greater extent that did either TCPP or hematoporphyrin. Both TCPP and TPPS4 were found to exhibit a greater inhibitory effect on clotting in the presence of light than did hematoporphyrin. In the absence of light and added Ca2+, both TCPP and TPPS4 were found to stimulate clotting at very specific porphyrin/fibrinogen concentration ratios, with TPPS4 being the more potent stimulator of the two. Hematoporphyrin exhibited little or no effect on clotting times. Fibrinogen, photoirradiated in the presence of the porphyrins was found to inhibit the clotting of unirradiated fibrinogen. A comparison of the stimulatory effects on clotting times by either calcium or TCPP and TPPS4 indicated that the porphyrins were capable of eliciting a greater stimulatory response than did calcium. The magnitude of the stimulatory response caused by the porphyrins alone was substantially reduced in the presence of calcium although the overall stimulatory response was increased but not additive. This suggests some interaction between either the calcium and porphyrin molecules or similarities in the respective stimulatory mechanism(s) involved. A possible correlation between these observations and the porphyrins ability to localize in tumors is also discussed.
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PMID:The effect of tumor localizing porphyrins on the conversion of fibrinogen to fibrin. 52 77

In order to investigate the frequency of fasting hypergastrinaemia in primary hyperparathyroidism (A) and in chronic hypercalcaemia (B), in 40 and 16 patients respectively gastrin, parathyroid hormone (PTH) and serum calcium levels were measured and compared with those of a control group (40 subjects) with similar distribution of sex and age. Moreover, possible linear relationships between these parameters were investigated. Notwithstanding significant differences in calcium and PTH levels between the three groups (A: high PTH, high Ca++; B: low PTH, high Ca++; C: normal PTH and Ca++ levels), no significant difference in gastrin levels were found. However, in the first group, a marked increase of gastrin was observed in one patient, very probably affected by a gastrin-secreting tumor (positive secretin test). While no linear relationship between PTH and gastrin values was present in all the three groups, a significant correlation between serum calcium and fasting gastrin was detectable in the group A, ruling-out the above mentioned patient. Present data suggest that PTH does not modify gastrin levels and that chronic moderate hypercalcaemia does not raise serum fasting gastrin, at least in clinical conditions. Moreover, the frequency of hypergastrinaemia in hyperparathyroidism is very low and it seems to be present only in patients with gastrin-secreting tumors.
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PMID:Fasting serum gastrin in primary hyperparathyroidism and in chronic hypercalcemia. 54 29


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