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

A transplantable mouse testicular teratoma (OTT 6050) which displays a spectrum of neuroepithelial differentiation was evaluated biochemically for concentrations of cyclic AMP (cAMP), serotonin (5-HT), and enzymes involved in the metabolism of the biogenic amines and acetylcholine. These values were compared between teratomas with neuroepithelial differentiation as the major or minor component and brains of neonatal and adult mice of related strains. cAMP, 5-HT, tryptophan hydroxylase (TPH), aromatic amino acid decarboxylase (AADC) and monoamine oxidase (MAO) were present. In addition, enzymes of the adrenergic system, i.e. tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH), and of the cholinergic system, i.e. choline acetyltransferase and acetylcholinesterase, were studied. Biochemical differences in tumor groups probably reflected variations in the proportion of neuroepithelial components: trends suggested an increase of cAMP and an increased activity of TPH, AADC, TH and DBH in tumors with increased proportions of neuroepithelial cells. These findings indicate that the neuroepithelial component of the mouse teratoma may serve as a model for the study of neuronal differentiation in primitive neuroepithelial neoplasms.
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PMID:Neurochemical studies in a mouse teratoma with neuroepithelial differentiation. Presence of cyclic AMP, serotonin and enzymes of the serotonergic, adrenergic and cholinergic systems. 0 Nov 40

Previous studies indicating the importance of catecholamine metabolism in neuroblastoma were briefly reviewed. Metabolic pathways were presented showing how the major urinary metabolites 3-methoxy-4-hydroxymandelic acid (VMA) and 3-methoxy-4-hydroxy-phenylacetic acid (HVA) are formed from norepinephrine and from dopamine plus 3,4-dihydroxyphenylalanine (DOPA), respectively. For 289 neuroblastoma patients at the time of diagnosis, the urinary excretion of VMA was significantly elevated in 75%, and HVA was elevated in 80%. Periodic assay of these metabolites during the course of the disease revealed that the excretion trends were of prognostic value with 80-90% reliability. By contrast, when the excretion in only the initial urine specimens was considered, the survival rate was the same for patients with normal, and with significantly elevated, excretion. Review of the results of tracer studies aimed at elucidating the in vivo metabolic origins of the urinary metabolites suggested that a) in neuroblastoma, the catecholamines were largely inactivated by intracellular metabolism in the tumor cells; b) there was excess production and excretion of the norepinephrine precursors, DOPA and dopamine; and c) in the tumors of most neuroblastoma patients, the initial enzyme in catecholamine synthesis, tyrosine hydroxylase, had an activity comparable with that in normal adrenal glands. The importance of the metabolism of catecholamines in patients with neuroblastoma was stressed: a) The excretion of elevated levels of urinary catecholamine metabolites were useful in diagnosis and in following the course of the disease, and b) study of the catecholamine metabolism in these patients permitted examination of possible relationships between the activity of the enzymes involved in catecholamine synthesis and the malignancy of this tumor.
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PMID:Catecholamine metabolism in neuroblastoma. 1 Apr 50

The synthesis of acetylcholine, as well as catecholamines, was studied by assaying the activities of choline acetyltransferase (ChA) and tyrosine hydroxylase (TH) in the tumor tissues and the culture cells of human neuroblastoma. In the majority of 20 neuroblastomas of sympathetic origin, both ChA and TH activities were detected at a significantly high level. In the culture cells of five cell lines of human neuroblastoma, ChA activity was high, but TH was negative in four of the lines. However, it was observed that these enzyme activities changed significantly while in the long-term culture. ChA assay is a useful diagnostic test for neuroblastomas that synthesize acetylcholine. Future studies of neuroblastoma should consider cholinergic activity.
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PMID:Acetylcholine synthesis in sympathetic human neuroblastoma. 1 56

Tyrosine hydroxylase, dopa oxidase, and peroxidase activities were studied in soluble fractions of B16 melanoma tumor homogenates by polyacrylamide gel disc electrophoresis. Stained gels were scanned photometrically and gel slices were assayed radiometrically. In these preparations, the two bands of tyrosine hydroxylating activity were completely separated from the peroxidase activity but coincided with two major bands of dopa oxidase activity. The third dopa oxidase band coincided with the single band of peroxidase activity. The soluble fraction of cultured cell homogenates had no peroxidase activity, but the two tyrosine hydroxylase bands coincided exactly with the two dopa oxidase bands. Therefore, in the soluble fraction of the murine melanoma bifunctional tyrosinase does exist as two electrophoretically separable forms which are independent of peroxidase.
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PMID:Characteristics of tyrosinase in B16 melanoma. 1 62

A 12-year-old boy with a norepinephrine-secreting pheochromocytoma that caused hypertension resistant to oral alpha adrenergic blockade is reported. Resistance to alpha adrenergic blocking agents developed when the patient's daily propranolol dosage was lowered from 10 to 1 mg/kg. Subsequently, alpha methyl tyrosine, an inhibitor of tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis, controlled the patient's blood pressure and was associated with reduction in total urinary catecholamine excretion. Norepinephrine content of the tumor and uninvolved adrenal gland removal at surgery was reduced. These findings confirm that alpha methyl tyrosine inhibited in vivo synthesis of catecholamines.
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PMID:Childhood pheochromocytoma: treatment with alpha methyl tyrosine for resistant hypertension. 1 59

We have established a clonal cell line, PC-G2, from an experimentally induced rat pheochromocytoma. Administration of nerve growth factor to PC-G2 causes a 4- to 8-fold induction in the specific activity of tyrosine hydroxylase [tyrosine 3-monooxygenase; L-tyrosine,tetrahydropteridine:oxygen oxidoreductase(3-hydroxylating); EC 1.14.16.2]. The response is elicited in a dose-dependent fashion, at concentrations above 0.1 microgram/ml. Antiserum to nerve growth factor inhibited the induction of tyrosine hydroxylase. Dexamethasone enhances the nerve growth factor-mediated elevation of tyrosine hydroxylase. After 3--4 days of exposure to nerve growth factor the maximal induction of tyrosine hydroxylase is seen, although a significant increase can be observed after 24 hr. In contrast to the PC-12 cell line (derived from the same tumor), in which neurite outgrowth occurs in response to nerve growth factor, there is no morphological change or alteration in growth rate of PC-G2 cells after exposure to nerve growth factor.
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PMID:Nerve growth factor-mediated induction of tyrosine hydroxylase in a clonal pheochromocytoma cell line. 3 87

Catecholamine storage was examined in cultures of the murine neuroblastoma cell line, N-TD6, using histofluorescence, electron microscopic, isotopic and radioautographic criteria. This line was originally derived from uncloned, C1300 tumor cells by selection in tyrosine deficient medium. N-TD6 cells possess both tyrosine hydroxylase (tyrosine-3-monooxygenase, EC 1.14.16.2) and dopamine beta-hydroxylase (dopamine beta-monooxygenase, EC 1.14.17.1) activities. When examined for paraformaldehyde-induced histofluorescence, a small percentage of cells in the population show intense catecholamine fluorescence, often localized within discrete regions of the cellular processes. Electron microscopic examination of these cells reveals both electron lucent vesicles and more frequent, electron dense granules, 50-70 nm and 100-300 nm in diameter, respectively. The distribution of these granules and vesicles varies, but they appear most numerous near the cell surface, along processes and within process endings. By labeling cells with [3H]dopamine and then allowing the cells to release unbound label in the presence of unlabeled dopamine, the localization of catecholamine stores was visualized by radioautographic techniques. While a variety of intracellular distribution of radioactivity were observed, the most prominent concentrations were found in the processes and their terminals; no labeled material was retained when reserpine was present during uptake. The topographic coincidence of granules, catecholamine fluorescence and [3H]dopamine retention in these neuroblastoma cells suggests that catecholamines are stored within these granules in a manner analogous to that observed in normal adrenergic neurons.
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PMID:Localized catecholamine storage associated with granules in murine neuroblastoma cells. 24 Apr 85

Catecholamine biosynthesis in tumor cells was studied in four patients, who expired from disseminated neuroblastoma. 1. The activity of tyrosine hydroxylase was detected in tumor tissues of all but one patient. 2. Dopamine-beta-hydroxylase activity was assayabel in almost all tissues, except in the primary tumor of one patient. 3. The enzyme activities in the metastatic lesions were at the same levels in two cases, but much higher in the other two cases, as those in the primary tumours. 4. It was learned that the urinary excretion of vanilmandelic acid (VMA) and homovanillic acid (HVA) in these patients reflects the tissue levels of catecholamine synthesizing enzymes as well as the tumor mass.
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PMID:Biochemical activity in the metastatic lesions of neuroblastoma. 24 12

The precursors tyrosine and tryptophan as well as the synthesizing and deaminating enzymes of catecholamines have been identified in methylcholanthrene-induced prostatic carcinoma of rats. Tyrosine hydroxylase, monoamine oxidase, catechol O-methyltransferase, dopamine, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid seemed to be neoplastic in origin, since electron microscopic studies failed to reveal the presence of any neuronal elements in this squamous epithelial cell carcinoma. Castration of rats significantly reduced the activity of tyrosine hydroxylase and the levels of tyrosine, dopamine, tryptophan, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid in prostate tumors. The changes appeared to be androgen specific since reintroduction of testosterone restored several of these biochemical parameters virtually to control limits. Chemical sympathectomy induced by 6-hydroxydopamine failed to alter monoamine metabolism; however, the prostatic tumor grown in 6-hydroxydopamine-treated rats showed significantly (32%) less necrosis than those grown in normal animals.
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PMID:Effect of testosterone and 6-hydroxydopamine treatment on the metabolism of catecholamine and 5-hydroxytryptamine in methylcholanthrene-induced prostate carcinoma of rats. 48 61

Tumor tissue located in the occipital lobe with hemorrhage was obtained from a 19-year-old patient. Histological examination indicated it to consist of undifferentiated small, round cells without neuronal or glial differentiation, and possibly to be a type of primitive neuroectodermal tumor. The tumor cells were cultured for 3 years and a continuous cell line (KK-2) was established. KK-2 was transplantable to nude mice. With immunocytochemistry, neuron-specific enolase, protein gene product 9.5, vimentin, TUJ1 (a monoclonal antibody specific for neuron-associated class III beta-tubulin isotype) and 6H7 (a monoclonal antibody to NCAM produced by us) were detected. None of the following could be found: glial fibrillary acidic protein, S-100 protein, neurofilament and synaptophysin, calcitonin gene-related peptide, gastrin releasing peptide corticotropin-releasing factor, substance P, somatostatin, chromogranin, aromatic L-amino acid decarboxylase and tyrosine hydroxylase. The original tumor and KK-2 cells obtained after 3 years of culture and transplants in nude mice displayed essentially the same ultrastructural and immunohistochemical characteristics. KK-2 cells showed no differentiation to mature neuronal, glial or ependymal cells. This cell line may possibly serve as a useful model for studying cellular differentiation of human neuroectodermal tumors and normal neuronal development.
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PMID:A continuous cell line (KK-2) from a supratentorial primitive neuroectodermal tumor. 132 7


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